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Abbreviation (ISO4): Prog Chem      Editor in chief: Jincai ZHAO

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Progress in Chemistry >

2023 , Vol. 35 >Issue 10: 1544 - 1558

DOI: https://doi.org/10.7536/PC230215

Review

Application of Pyrite and Its Modified Composite in Water Pollution Treatment

  • Yanxiao Chi 1 ,
  • Yuxuan Yang 1 ,
  • Kunlun Yang , 1, 2, * ,
  • Xianrong Meng 2 ,
  • Wei Xu 2 ,
  • Hengfeng Miao 1
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  • 1 College of Environment and Civil Engineering, Jiangnan University,Wuxi 214122, China
  • 2 Suzhou Institute of Environmental Science, Jiangsu Postdoctoral Innovation Practice Base,Suzhou 215009
*Corresponding author e-mail:

Received date: 2023-02-16

  Revised date: 2023-04-18

  Online published: 2023-08-07

Supported by

National Natural Science Foundation of China(22206061)

Fundamental Research Funds for the Central Universities(JUSRP122022)

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Abstract

Due to its strong surface activity, precipitation adsorption, redox and relatively excellent photocatalytic properties, pyrite has been widely used to treat heavy metals, organic pollutants and various inorganic salts in the polluted water. However, some inherent defects of pyrite, such as small specific surface area, high susceptibility to agglomeration, etc., limit its practical applications. Appropriate modification of pyrite via morphological adjustment, elemental doping, and material loading can improve the dispersion performance of particle size, expose more functional groups and increase electron transport rate to further modulate the related properties and enhance the wastewater treatment capacity of pyrite, In this article, we firstly introduce the basic information, the application and the mechanism of pyrite in wastewater treatment, and then describe the typical modification methods of pyrite and their corresponding strengthening mechanisms for treating wastewater. This article will provide a systematic introduction and outlook for the development of pyrite-based composite materials in the field of environmental treatment.

Contents

1 Introduction

2 Adsorption of pyrite

2.1 Application and mechanism of pyrite adsorption capacity

2.2 Improvement of pyrite materials and enhancement of adsorption capacity

3 Oxidation of pyrite

3.1 Application and mechanism of pyrite oxidation ability

3.2 Improvement of pyrite materials and enhancement of oxidation capacity

4 Reduction of pyrite

4.1 Application and mechanism of pyrite reduction ability

4.2 Improvement of pyrite materials and enhancement of reduction capacity

5 Conclusion and outlook

Key words： pyrite; modification; functional regulation; water pollution treatment

Cite this article

Yanxiao Chi , Yuxuan Yang , Kunlun Yang , Xianrong Meng , Wei Xu , Hengfeng Miao . Application of Pyrite and Its Modified Composite in Water Pollution Treatment[J]. Progress in Chemistry, 2023 , 35(10) : 1544 -1558 . DOI: 10.7536/PC230215

1 Introduction

With the sustainable development of science and technology and society, the problem of water environmental pollution is becoming more and more serious[1]. Pyrite is the most abundant metal sulfide on the earth's surface. It has a perfect crystal form, which is similar to the crystal structure of sodium chloride (Fig. 1). It is easy to process and environmentally friendly. Because of its surface solubility, precipitation adsorption, oxidation and reduction, it has attracted wide attention in water pollution treatment[2][3]. The oxidation and dissolution characteristics of pyrite in aqueous solution are a hot research topic in geochemistry and environment, and the released ferrous ions and reduced sulfide species can participate in the redox reaction as electron donors.A variety of reactive oxygen species (ROS) can directly mineralize organic pollutants and natural organic matter (NOM) into carbon dioxide, change the metabolic pathways of pollutants, and reduce the toxicity of pollutants[4][5]. In addition, pyrite is also photochemically active, showing great potential in photocatalysis with its narrow band gap (Eg=0.95 eV) and high light absorption coefficient (α>6×105cm-1,λ≤700nm), which is widely used in the adsorption and photocatalytic removal of pollutants and heavy metals[6].
图1 黄铁矿的晶体结构[10]

Fig.1 Crystal structure of pyrite[10]

However, pyrite is also limited in the treatment of water pollution due to its small specific surface area, low reactivity, limited active sites and easy agglomeration, so the necessary structural control and modification methods have been widely studied to improve its performance in practical applications[7]. For example, synthetic pyrite usually has higher reactivity than natural pyrite, which can effectively avoid the influence of doped elements and crystal defects in natural pyrite on the reaction, and pyrite of specific size or purity can be obtained by simple hydrothermal reaction[8,9]. In addition, engineering carbon materials such as activated carbon, biochar and carbon nanotubes loaded with pyrite can effectively increase the particle dispersion, reduce agglomeration and increase the specific surface area of the materials. Element doping can cause changes in the structure of pyrite, resulting in changes in physical and chemical properties. Pyrite itself is a semiconductor material, and its photocatalytic performance can be effectively enhanced by combining semiconductor materials with different band gap widths or strong oxidizing semiconductors to construct heterostructures.
In this paper, the research progress of pyrite in water environment treatment is reviewed, focusing on the oxidation, reduction, adsorption capacity and mechanism of pyrite, and the application of pyrite in environmental treatment in recent years, such as the removal of heavy metal ions, non-metallic ions and the degradation of organic pollution, is introduced in detail. The development prospect of pyrite and its modified materials, as well as the limitations of pyrite and its modified materials in practical application such as environmental governance, are discussed.

2 Adsorption of pyrite

The surface of pyrite has rich active functional groups and special physical and chemical properties, which makes it have good adsorption for organic pollutants, heavy metal ions and some anions[2]. It can form Fe3+ hydroxide under acidic conditions, which has a strong adsorption capacity for heavy metals, and can be used to remove pollutants by using the principle of precipitation and dissolution equilibrium and its own adsorption properties, or by physical and chemical combination with adsorbates through electrostatic interaction on the surface, which is more and more used in sewage treatment[3,5,11][12][13].

2.1 Adsorption mechanism of pyrite and its application

2.1.1 Adsorption and removal of heavy metal by pyrite

As a good adsorption material, pyrite is widely used in the adsorption of a variety of heavy metals or metalloid ions such as antimony, mercury, cadmium, uranium, arsenic and so on[14][15][16][17][18,19]. It can adsorb heavy metal ions in the solution and then solidify the heavy metal ions by co-precipitation, so as to achieve the purpose of pollution remediation[20].
Bulut et al. Studied the adsorption effect of pyrite on As (Ⅲ). At pH = 5, the removal rate of As (Ⅲ) could reach 99% (the initial As (III) concentration was 38.5 mg/L) by adding 15 G/L pyrite. The results showed that the oxidation and particle size of pyrite had a great influence on the removal of As (III)[18]. Shi Song et al. Selected natural pyrite to adsorb Sb (Ⅴ), and when the initial concentration of Sb (Ⅴ) was 90 ~ 100 μg/L, the removal rate of Sb (Ⅵ) was more than 80% (pyrite particle size 200 mol/L, dosage 1 G/L, pH = 7)[14]. The characterization results show that Sb (Ⅴ) is adsorbed on the surface of pyrite and is not reduced to Sb (Ⅲ), which is more toxic, mainly through chemical adsorption and surface coordination ion exchange. On the other hand, the adsorption of pyrite can also be applied to the sequestration of nuclear waste. He Ye studied the adsorption of U (Ⅵ) in uranium-contaminated groundwater by natural pyrite. The results showed that the removal rate of U (Ⅵ) was the highest at pH = 7 ~ 8. It was pointed out that the adsorption of U (Ⅳ) by pyrite was mainly surface adsorption[17].
The adsorption of pyrite can be divided into two aspects, on the one hand, it depends on the interaction of surface functional groups or metal ions to form insoluble precipitates to remove metal ions. The surface of natural pyrite contains two kinds of functional groups, S-H (thiol group) and Fe-OH (hydroxyl group), among which S-H has a strong affinity with Hg2+ and Cd2+, and can remove heavy metal ions from water by adsorption and complexation[21]. Gan et al. Found that when pyrite treated acidic wastewater containing Cr (Ⅵ), Cr (Ⅵ) reacted with hydroxyl groups in minerals at a certain acidity to promote the adsorption and precipitation of heavy metal ions by minerals[22]. Arsenic can also be chemically adsorbed on the pyrite surface by iron hydroxides produced by pyrite oxidation through bidentate shared edge and biangular shared surface complexation[23].
On the other hand, electrostatic attraction has also been confirmed to play an important role in the adsorption of heavy metals by pyrite. Luo et al. Studied the adsorption of gold nanoparticles with different charges on pyrite[24]. They used pyrite to adsorb negatively and positively charged AuNPs, respectively, and the results showed that almost no adsorption was observed due to the electrostatic repulsion between the positively charged AuNPs and the pyrite surface. On the contrary, the negatively charged AuNPs can be significantly adsorbed on pyrite by electrostatic attraction, and the adsorption degree decreases with the increase of pH value (pH = 2.2 ~ 9.1). This study proves that electrostatic interaction is the main mechanism of AuNPs adsorption on natural pyrite. The adsorption process is similar to that shown in Fig. 2.
图2 黄铁矿吸附重金属的反应机理图[25]

Fig.2 Mechanism of pyrite adsorbing heavy metals[25]

2.1.2 Adsorption and removal of inorganic salts by pyrite

The rapid development of industry and agriculture in China has led to a large number of production sewage and urban domestic sewage rich in N and P, resulting in serious eutrophication of rivers, lakes and other water bodies. How to effectively remove N and P elements has become the most important way to alleviate eutrophication and treat polluted water[26⇓~28].
Previous studies have found that pyrite can release iron ions continuously and slowly in aerobic environment, which has a certain potential in phosphorus removal[26]. Zhang Jing et al. studied the phosphorus removal performance of natural pyrite, and the removal of phosphorus by pyrite reached equilibrium at 12 H, with a removal amount of 6.82 mg/kg (the initial phosphorus concentration was 2 mg/L)[28]. It is pointed out that the removal of phosphorus in water is mainly through the formation of iron-phosphorus precipitates by the combination of iron and phosphorus, and the adsorption of phosphorus by various iron oxides and hydroxides. Wang Ju et al. Also proved the adsorption effect of natural pyrite on phosphorus (the removal rate is more than 95% in the range of pH = 3 ~ 9.65)[26]. On the other hand, the potential of pyrite for nitrogen removal was demonstrated by nitrate reduction with the participation of microorganisms using pyrite as an electron donor[29]. Torrent et al. Studied the effect of pyrite on denitrification of groundwater, and the results showed that pyrite could enhance the removal of nitrate, and denitrifying bacteria could use pyrite as an electron donor to reduce nitrate, thus promoting denitrification of nitrogenous water[30]. In addition, pyrite can also adsorb some oxyacid radicals of metal ions on the surface by its own action, and then redox reaction occurs to remove pollutants. Wang Dan et al. Studied the adsorption performance of natural pyrite for selenate in aqueous solution. In the pH range of 2.2 ~ 11.5, the adsorption rate of nano-pyrite for Se (Ⅳ) was more than 92% (the saturated adsorption capacity was 3.89 mg/G), indicating that pyrite could be effectively used for the removal of Se (Ⅳ) in water[31]. Bostick et al. Reported that pyrite has a very good adsorption effect on molybdate ( M o O 4 2 -) and tetrathiomolybdate ( M o S 4 2 -)[32].
The mechanism of phosphorus removal by pyrite is mainly the chemical adsorption of phosphorus by ferric iron produced by the slow oxidation of pyrite surface (Formula 1 ~ 4), and the reaction of the produced iron ions with phosphate ions in wastewater on the surface of pyrite to form iron phosphate precipitation (Formula 5 ~ 8)[26]. In addition, ferrous ions and iron ions produced in the oxidation process of pyrite will hydrolyze with hydroxyl ions to produce Fe(OH)2 and Fe(OH)3,Fe(OH)2, which are easily oxidized into Fe(OH)3,Fe(OH)3 to adsorb phosphorus in wastewater. In the process of pyrite treatment of phosphorus-containing wastewater, the time of precipitation formation is relatively short, but the adsorption always exists.
$2 \mathrm{FeS}_{2}+7 \mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 2 \mathrm{Fe}^{2+}+4 \mathrm{SO}_{4}^{2-}+4 \mathrm{H}^{+}$
$4 \mathrm{Fe}^{2+}+\mathrm{O}_{2}+4 \mathrm{H}^{+} \rightarrow 4 \mathrm{Fe}^{3+}+2 \mathrm{H}_{2} \mathrm{O}$
$\mathrm{FeS}_{2}+14 \mathrm{Fe}^{3+}+8 \mathrm{H}_{2} \mathrm{O} \rightarrow 15 \mathrm{Fe}^{2+}+16 \mathrm{H}^{+}+2 \mathrm{SO}_{4}^{2-}$
$\mathrm{Fe}^{3+}+3 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{Fe}(\mathrm{OH})_{3}+3 \mathrm{H}^{+}$
$3 \mathrm{Fe}^{2+}+2 \mathrm{PO}_{4}^{3-} \rightarrow \mathrm{Fe}_{3}\left(\mathrm{PO}_{4}\right)_{2} \downarrow$
$\mathrm{Fe}^{3+}+\mathrm{PO}_{4}^{3-} \rightarrow \mathrm{FePO}_{4} \downarrow$
$\mathrm{Fe}^{3+}+\mathrm{H}_{2} \mathrm{PO}_{4}^{-} \rightarrow\left[\mathrm{FeH}_{2} \mathrm{PO}_{4}\right]^{2+}$
$\mathrm{Fe}^{3+}+\mathrm{HPO}_{4}^{2-} \rightarrow\left[\mathrm{FeHPO}_{4}\right]^{+}$
Thiobacillus denitrificans and denitrifying bacteria are the main bacteria in pyrite-based autotrophic denitrification system. Both bacteria can oxidize sulfide to sulfate by using nitrate as an electron acceptor[33]. The denitrification process with pyrite as the electron donor is shown in Equation (9)[34]. In addition, the Fe2+ released in pyrite autotrophic system can also participate in autotrophic denitrification as an electron donor, as shown in formula (10). More importantly, the iron ions released from the pyrite autotrophic system will react with P O 4 3 - (Equation 11) to form ferric phosphate precipitate, thus achieving the purpose of phosphorus removal[26,35].
$0.364 \mathrm{FeS}_{2}+\mathrm{NO}_{3}^{-}+0.821 \mathrm{H}_{2} \mathrm{O}+0.116 \mathrm{CO}_{2}+0.023 \mathrm{NH}_{4}^{+} \\ \rightarrow 0.023 \mathrm{C}_{5} \mathrm{H}_{7} \mathrm{O}_{2} \mathrm{~N}+0.364 \mathrm{Fe}(\mathrm{OH})_{3}+0.48 \mathrm{H}^{+}+0.5 \mathrm{~N}_{2} \\ \uparrow+0.729 \mathrm{SO}_{4}^{2-}$
$\mathrm{Fe}^{2+}+\mathrm{NO}_{3}^{-}+6 \mathrm{H}^{+} \rightarrow \frac{1}{2} \mathrm{~N}_{2} \uparrow+5 \mathrm{Fe}^{3+}+3 \mathrm{H}_{2} \mathrm{O}$
$\mathrm{Fe}^{3+}+\mathrm{PO}_{4}^{3-} \rightarrow \mathrm{FePO}_{4} \downarrow$

2.1.3 Removal of organic pollutants by pyrite adsorption

It has been reported that the defect sites on the surface of natural pyrite make its surface rich in chemical composition, and iron or sulfur ions are exposed on the surface, which can be used as adsorption centers for various ionic species[36]. This natural mineral is easy to react with a large number of ionized groups of humic acid molecules in water through electrostatic adsorption or chemical adsorption, and its mechanism is mainly related to the chemical composition and surface properties of pyrite[37]. These characteristics make the application of natural pyrite in the treatment of water pollution more and more extensive and mature.
Fang Yanfen et al. Used pyrite as adsorbent to study its adsorption characteristics on two typical humic acids (fulvic acid (FA) and humic acid (HA)) in water, and obtained good adsorption effect (the maximum adsorption capacity of FA and HA was 11.8 mg/G and 13.1 mg/G, respectively)[37]. Cai Kuan et al. Used pyrite as adsorbent to study the adsorption characteristics of Rhodamine B (Rh B), and the adsorption capacity reached the maximum of 21.3 mg/G when the adsorption equilibrium time was 120 min and pH = 4[38]. Hu Junsong et al. Studied the adsorption performance and mechanism of glyphosate on natural pyrite, and the results showed that higher pH, lower temperature and certain phosphate content could promote the adsorption of glyphosate on pyrite[39].
The adsorption of organic pollutants on pyrite can be divided into two aspects: chemical adsorption and physical adsorption, and the surface chemical morphology of pyrite has a decisive impact on the adsorption behavior. Zheng et al. Studied the adsorption behavior of cysteine on the pyrite surface, and the DFT calculation results showed that cysteine was mainly adsorbed on the Fe surface of pyrite (100) in the form of chemical bonds, while it was mainly adsorbed on the S surface of pyrite (100) in the form of physical adsorption[10]. Pyrite can accept electrons from cysteine, and Fe on the surface of pyrite (100) is electron-deficient, while S is electronegative, so cysteine can be adsorbed on the Fe site through chemical bonding. Wang et al. Analyzed the adsorption behavior of glucose on the surface of pyrite, and the results showed that glucose could be rapidly adsorbed on the surface of pyrite within 60 min. It was pointed out that the physical adsorption through electrostatic interaction mainly controlled the interaction between glucose and pyrite[40]. Han et al. Studied the adsorption behavior of salicylic acid (HA) on the surface of pyrite. Zeta potential and infrared spectrum analysis showed that there were both physical adsorption and chemical adsorption in the adsorption process of HA on the surface of pyrite, mainly through the interaction with active iron atoms to form abundant hydrophilic groups[41]. The adsorption process of organic pollutants by pyrite is shown in Fig. 3.
图3 黄铁矿吸附有机污染物的机理图

Fig.3 Mechanism of pyrite adsorbing organic pollutants

2.2 Improvement of pyrite-based materials and enhancement of their adsorption capacity

2.2.1 Removal of heavy metals by modified pyrite adsorption

Although pyrite, as a natural mineral, has been widely used in the adsorption and removal of heavy metals or metal-like ions because of its wide source and eco-friendly, it also has some defects in practical application, such as small specific surface area and insufficient surface active sites, which leads to its insufficient adsorption capacity and limits its application in heavy metal water treatment. Therefore, the surface structure of pyrite can be changed by modification, artificial synthesis or compounding with other materials to enhance the performance of heavy metal removal and treat different types of wastewater more effectively[20]. The main modification methods are ball milling, thermal modification, element doping and material loading, and the typical enhancement methods are shown in Figure 4.
图4 提高黄铁矿吸附去除重(类)金属的几种典型策略

Fig.4 Some typical strategies to enhance the adsorption performance of pyrite for the removal of heavy metals

It is widely believed that the smaller the particle, the more favorable it is for adsorption because of its larger specific surface area. Pourghahramani et al. Compared the adsorption and removal performance of natural pyrite and ball milled pyrite on lead ions, and they pointed out that the increase of reactivity of natural pyrite after ball milling was mainly attributed to the change of mineral structure.The new surface and defect sites formed by mechanical activation can significantly enhance the reaction rate and reactivity, and the adsorption capacity of Pb2+ increases from 4. 95 mg/G for natural pyrite to 34. 10 mg/G for mechanically activated pyrite[42]. He et al. Used ball milling technique to synthesize ball-milled micron-sized BM-ZVI/FeS2 composite to obtain larger specific surface area[20]. The removal efficiency of Sb (V) by BM-ZVI/FeS2 reached 99.18% in Sb (V) solution with initial concentration less than 100 mg/L, and showed good removal efficiency in a wide pH range (pH = 2.6 – 10.6). It is pointed out that ZVI is completely corroded on the BM-ZVI/FeS2 to produce more adsorption centers, the iron hydroxide shows a high affinity for Sb (Ⅴ), and the S-H adsorption centers participate in the adsorption of Sb (Ⅴ) to form a bidentate mononuclear complex on the iron hydroxide.
Thermal modification of pyrite may be an effective method to improve the adsorption capacity. Sulfur vacancy (SV), as a common defect on the surface of pyrite, is of great significance in the adsorption of heavy metals. Hu Guoliang et al introduced SV on the surface of pyrite by hydrothermal-vacuum heat treatment. The experimental results showed that the introduction of SV increased the adsorption capacity of Ni (II) on FeS2 from 4. 17 mg/G to 6. 45 mg/G[21]. The introduced surface SVs can act as reactive sites for the dissociation and activation of water adsorbed on the surface of FeS2 to form ortho-iron hydroxyl groups (≡ Fe-OH), thereby improving the adsorption and complexation ability of FeS2 for Ni (Ⅱ). He et al. Synthesized FeS2/α-Fe2O3 composite in situ by thermal modification of pyrite, and constructed Fe (Ⅱ) -Fe (Ⅲ) system for remediation of Sb (Ⅴ) pollution in sewage[43]. The results showed that FeS2/α-Fe2O3 had a large adsorption capacity for Sb (Ⅴ) in water, and (347.2 mg/g),FeS2/α-Fe2O3 showed a high removal efficiency in a wide pH range (pH = 2.5 ~ 10.7). The analysis showed that both S-H (thiol group) and Fe-OH (hydroxyl group) on the surface of the FeS2/α-Fe2O3 composite material had high affinity for Sb (Ⅴ), and formed a bidentate mononuclear spherical surface complex with Sb (Ⅴ), thus fixing Sb (Ⅵ).
Element doping is also a common modification method. Impurity elements replace Fe atoms, resulting in changes in the structure of pyrite, and ultimately lead to changes in the physical and chemical properties of pyrite. Huang Shujie synthesized pyrite doped with impurity element Ni, and explored the effect of impurity components on the adsorption/reduction of Se (Ⅳ) on pyrite[44]. The results show that the lower the initial pH is, the faster the removal of Se (Ⅳ) by Ni-doped pyrite is, and the adsorption rate of Se (Ⅳ) by Ni-doped pyrite is close to 100% after 24 H at initial pH = 4. 5. This is mainly due to the significant increase in the specific surface area of Ni-bearing pyrite (24.67~29.53 m2/g), which is much larger than that of pure pyrite (3.02 m2/g).
Combining pyrite with other components can also effectively improve the adsorption performance. Qi et al. Mixed pyrite (PY) with acid-modified fly ash (AC-FA) to prepare Hg (Ⅱ) adsorbent of pyrite modified fly ash (PY + AC-FA), and obtained good mercury removal effect[45]. The characterization results show that pyrite is successfully loaded on the surface of the modified fly ash to obtain a larger specific surface area and pore size. When the reaction temperature is 50 ℃, the doping amount of modified fly ash is 20 wt%, and the mass ratio of pyrite to acid-modified fly ash is 4 ∶ 1, the adsorption rate of Hg (Ⅱ) reaches 91. 92%. It is speculated that the possible mechanism of mercury removal is that Hg0 is first adsorbed on the surface of the adsorbent and then oxidized to gaseous HgS by pyrite, and most of Hg (Ⅱ) is adsorbed on the surface of the adsorbent in the form of HgS. Table 1 summarizes the adsorption removal of heavy metal ions in water by pyrite functionally regulated and modified by ball milling activation, loading, and element doping.
表1 黄铁矿改性材料吸附去除重(类)金属

Table 1 Adsorption and removal of heavy metals by pyrite modified materials

Modification method Modification material Target metal Removal performance ref
Ball-milling BM-ZVI/FeS2 Sb(V) 134 mg/g 20
BM-FeS2 Pb(Ⅱ) 34.10 mg/g 42
BM-FeS2 Cr(Ⅵ),Cd(Ⅱ),Pb(Ⅱ) 4.75 mg/g, 2.87 mg/g, 4.91 mg/g 46
Thermal modification SV-FeS2 Ni(Ⅱ) 6.45 mg/g 21
FeS2/α-Fe2O3 Sb(V) 347.2 mg/g 43
Element doping Ni-FeS2 Se(Ⅳ) 15.79 mg/g 44
Loading PY+AC-FA Hg(Ⅱ) 239.26 μg/g 45

2.2.2 Removal of inorganic salts by modified pyrite adsorption

Pyrite autotrophic denitrification system has the potential of deep removal of nitrogen and phosphorus in water. However, pyrite-based denitrification systems generally require a long hydraulic retention time (24 H), which limits the application of pyrite in practical wastewater treatment[47]. The reason for the slow reaction may be that the specific surface area of natural pyrite particles is small, which is easy to agglomerate in the reaction, and the removal performance of dissolved nutrients is unstable. Therefore, increasing the specific surface area of pyrite particles and increasing the reaction rate are the key to improve the applicability of pyrite phosphorus and nitrogen removal system[29].
Kong et al. Developed a modified biochar-pyrite (FeS2) two-layer biological system, which showed high stability and efficiency for dissolved nutrient treatment, and the removal rates of ammonium salt, total nitrogen and total phosphorus were 95.3% – 98.1%, 41.4% – 76.5% and 69.7% – 88.2%, respectively[48]. They pointed out that the addition of biochar promoted ammonium adsorption, nitrification and in situ denitrification, and also intercepted dissolved oxygen, thus reducing pyrite oxidation and achieving stable mixotrophic denitrification. In addition, pyrite particles can be transformed into particles with polycrystalline and porous structure by calcination, resulting in larger specific surface area (SSA) and pore size (PD). Li et al. Designed a new type of biological aerated filter (BAF) with calcined pyrite to remove nitrogen and phosphorus in water, which effectively improved the effect of nitrogen and phosphorus removal[49]. In addition to nitrogen and phosphorus removal, modified pyrite has also been used to adsorb oxyacid radicals from other metal ions. Xu et al. Used a combined substrate of pyrite and cinder to remove molybdate ( M o O 4 2 -) from water by adsorption, and obtained a good removal effect (16.25 mg/G)[50]. The results show that the mixed matrix of pyrite and cinder is feasible as a filter medium for Mo (Ⅵ) removal.

2.2.3 Removal of Organic Pollutants by Modified Pyrite Adsorption

Changing the surface properties of pyrite can effectively improve the adsorption capacity of minerals. Intense UV radiation is thought to alter pyrite surface properties, causing physical/chemical changes[36,51]. Galvez-Martinez et al. studied the adsorption of triglycine on the pyrite surface under different conditions, and pointed out that ultraviolet radiation on the pyrite surface before molecular adsorption can effectively enhance the adsorption performance of organic molecules on the mineral surface[36]. The chemical composition of pyrite surface is highly sensitive to the chemical changes caused by UV irradiation, and strong radiation may cause a certain degree of oxidation on the surface of pyrite, which makes the surface of pyrite more active and enables it to accumulate more molecules, which is beneficial to the reaction between molecules. Ion sputtering and annealing can also effectively change the surface properties of minerals. Galvez-Martinez et al. Used Ar+ ion sputtering and annealing to change the surface properties of pyrite to enhance the adsorption properties of glycine[52]. They pointed out that the sputtering and annealing processes drive electrostatic changes on the pyrite surface, promoting the generation of sulfur vacancies and iron dangling bonds, which play an important role in the molecular adsorption of glycine.
In addition, the degree of crystallization of the crystal phase also has an important influence on the surface properties of pyrite. The results show that the surface activity of amorphous pyrite is stronger, which is more conducive to the adsorption of pollutants[53]. Gadisa et al. Studied the adsorption capacity of amorphous FeS2 nanowires for organic dyes Congo red (CR) and methylene blue (MB), and showed excellent adsorption performance (theoretical adsorption capacity of 118.86 and 48.82 mg/G, respectively)[54]. The characterization results show that the FeS2 nanowires have high specific surface area and negative Zeta potential in a wide pH range, and the adsorption process (physical adsorption) is driven by the electrostatic attraction between the adsorbent surface and the dye molecules, and then the chemical adsorption is carried out through the interaction between the sulfonic acid groups on the dye surface and the adsorbent surface.

3 Catalytic oxidation of pyrite

As the most abundant mineral in the earth's crust, pyrite is easily oxidized in real aqueous environments, releasing species such as Fe2+ and Fe3+[55]. Pyrite reacts with dissolved oxygen (DO) to generate various ROS, such as hydrogen peroxide (H2O2), hydroxyl radical (· OH), and superoxide radical ( · O 2 -), which are believed to be responsible for the oxidation of various metal ions and organic pollutants[56]. In practical applications, it is usually accompanied by adsorption to remove various pollutants.

3.1 Catalytic oxidation mechanism of pyrite and its application

3.1.1 Oxidative removal of heavy metals by pyrite

Heavy metal pollution mainly comes from various industrial activities, which causes great harm to human production activities[57,58]. Pyrite is widely used in the treatment of heavy metal or metalloid wastewater by its own oxidation ability, which can oxidize the low-valent heavy metal ions with high toxicity and strong fluidity into high-valent metal ions with low toxicity and strong adsorption, so as to remove heavy metals such as arsenic and antimony in wastewater, and become a promising method for the treatment of heavy metal pollution.
It has been found that natural pyrite coexisting in acid mine drainage can interact with As. Liu et al pointed out that arsenite (As (Ⅲ)) can be adsorbed and redox on the surface of pyrite under solar irradiation, and solar radiation promotes this reaction to produce various ROS to oxidize As (Ⅲ)[56]. Kong et al. Confirmed that pyrite can oxidize Sb (Ⅲ) to Sb (V) on the surface, and the oxidation effect of Sb (Ⅲ) increases with the increase of pH[59]. They pointed out that the main oxidizing species are pyrite-induced hydroxyl radical (· OH) and hydrogen peroxide (H2O2), where · OH is the oxidant of Sb (Ⅲ) oxidation in acidic solution, while H2O2 is the main oxidant in neutral and alkaline solutions.
Yan et al. Pointed out that the oxidizing ability of pyrite in the reaction mainly comes from the formation of secondary minerals and the redox and fixation of heavy metals, such as H2O2, · OH and · O 2 -, mediated by various ROS with strong oxidizing ability produced in the reaction[60]. Some previous studies have shown that pyrite in aqueous solution can release dissolved Fe2+,Fe2+ to generate ROS through electron transfer with active oxygen adsorbed on the surface of pyrite (Equation 18)[61]. First the Fe2+ ion gives an electron to DO, and then the resulting Fe3+ rapidly accepts an electron from pyrite. The generated Fe3+ acts as a channel for electron transfer from the FeS2 surface to the O2 molecule, forming the · O 2 - species (Formula 12), which in turn produces · OH oxidizing heavy metals under acidic conditions (Formulas 13 – 15). In addition, there are sulfur defect sites on the pyrite surface, where Fe3+ can react with adsorbed H2O to form · OH (Formula 16), and two · OH radicals can combine to form H2O2 (Formula 17), and the generated · OH and H2O2 contribute to the oxidative fixation of heavy metals[59]. The reaction process is shown in fig. 5.
Fe2++O2→Fe3++ · O 2 -
Fe2++ · O 2 -+2H+→Fe3++H2O2
Fe2++H2O2→Fe3++·OH+OH-
Fe2++·OH→Fe3++OH-
Fe3++H2O→Fe2++·OH+H+
·OH+·OH→H2O2
Fe(OH)++H2O2→Fe(OH)2++·OH+OH-
图5 黄铁矿氧化去除重金属的机理图

Fig.5 Mechanism of heavy metal removal by pyrite oxidation

3.1.2 Degradation of organic pollutants by pyrite catalytic oxidation

In today's increasingly serious organic pollutants, advanced oxidation processes (AOPs) is a typical and effective method to treat wastewater with high concentration of refractory organic compounds, and its main reaction mechanism is shown in Fig. 6. The oxidation of pyrite in aqueous solution produces many intermediates, such as Fe2+, S0, H2S and polysulfides, which are very active in advanced oxidation reactions[4]. In AOPs, pyrite slowly releases Fe2+ to trigger advanced oxidation reactions, and the interaction between Fe3+ and pyrite in turn promotes the regeneration of Fe2+ and the Fe2+/Fe3+ cycle. The application of pyrite in AOPs is mainly divided into Fenton oxidation, electro-Fenton oxidation and persulfate oxidation.
图6 黄铁矿介导的Fenton氧化和过硫酸盐氧化降解有机污染物的反应机理图[4]

Fig.6 Proposed mechanisms of pyrite-mediated Fenton oxidation and persulfate oxidation processes for the degradation of organic pollutants[4]

Under the condition of external addition of H2O2, Fe2+ and H2O2 undergo Fenton reaction to produce · OH with strong oxidizing ability to achieve effective degradation of refractory organic pollutants (Formula 14). For example, Zhao et al. Used FeS2-H2O2 system to degrade chloramphenicol (CAP), and the removal rate of CAP reached 100% under acidic conditions[62]. Electro-Fenton does not require additional H2O2. Compared with the traditional Fenton oxidation method, electro-Fenton oxidation method electrochemically generates H2O2 to produce · OH. H2O2 produced at the cathode by two-electron reduction of O2 under acidic conditions (formula The regeneration of 19),Fe2+ can also be achieved by cathodic reduction of Fe3+ in solution (formula 20). Yu et al. Confirmed that FeS2 could efficiently catalyze the decomposition of diclofenac sodium (DCF) in a wide pH range (pH = 3 – 9), and the degradation rate reached 100% after 8 min of reaction (pyrite dosage was 0.8 G and initial DCF concentration was 50 mg/L)[63]. In the electro-Fenton system, pyrite is mainly used as the iron source in the electro-Fenton oxidation process, which avoids the use of soluble iron salts or the loss of metal electrodes in the traditional electro-Fenton oxidation process[64,65]. In addition, different from the strong oxidation ability of traditional AOPs based on · OH, persulfate (including PMS and PDS) oxidation technology uses sulfate radicals ( S O 4 · -) as the main active substance for the degradation of organic pollutants, and its oxidation ability is close to that of · OH. The Fe2+ provided by pyrite can effectively activate persulfate, and the peroxygen bond in persulfate is broken through energy and electron transfer to produce S O 4 · - (Formula 21, 22), which has more advantages compared with · OH. Rahimi et al. Used natural pyrite to activate PMS to degrade tetracycline (TC), and 98.3% of TC (initial concentration 50 mg/L) was degraded within 30 min using pyrite-activated PMS[66]. It is confirmed that pyrite nanoparticles can be considered as a non-toxic and clean catalyst for refractory water pollutants.
O2+2H++2e-→H2O2
Fe3++e-→Fe2+
$\mathrm{Fe}^{2+}+\mathrm{HSO}_{5}^{-} \rightarrow \mathrm{Fe}^{3+}+\mathrm{SO}_{4}^{.-}+\mathrm{OH}^{-}$
$\mathrm{Fe}^{2+}+\mathrm{S}_{2} \mathrm{O}_{8}^{2-} \rightarrow \mathrm{Fe}^{3+}+\mathrm{SO}_{4}^{.-}+\mathrm{SO}_{4}^{2-}$
The main process of pyrite Fenton reaction is as follows: after pyrite releases Fe2+, Fe2+ and H2O2 undergo Fenton reaction to produce · OH, which attacks and degrades organic pollutants (Formula 19). Fe3+ can be reduced to Fe2+(Fe2+/Fe3+ cycle) by the process shown in equation (23), which is a rate-limiting step of the Fenton process[67]. In addition to Fe2+, H2O2 oxidation of pyrite in Fenton system can also produce Fe3+ (Equation 24)[68]. The pH value of Fenton system can be effectively adjusted by hydrogen ions in the process of iron release from pyrite[68]. Therefore, pyrite promotes the Fe2+/Fe3+ cycle in the Fenton process, thereby promoting the subsequent oxidative degradation of organic matter to produce · OH.
Fe3++H2O2→Fe2++H++HO2
2FeS2+15H2O2→2Fe3++ 4 S O 4 2 -+2H++14H2O
The pyrite-mediated electro-Fenton oxidation process is dominated by the reduction of dissolved O2 at the cathode to produce H2O2 (Equation 19), while pyrite oxidative dissolution releases Fe2+ and Fe3+ (Equations 1, 12). The released Fe2+ can directly react with the cathode-generated H2O2 by Fenton reaction. However, both the released Fe3+ and the Fe3+ generated by Fenton reaction can be reduced to Fe2+ through various pathways, including pyrite reduction (Equation 2) and cathodic reduction (Equation 15). These processes promote the Fe2+/Fe3+ cycle and promote the formation of · OH in the electro-Fenton system.
Pyrite releases Fe2+ through persulfate oxidation, and the released Fe2+ activates PMS and PDS to produce S O 4 · - through (Equations 21 and 22). In addition, pyrite can also be directly oxidized to produce S O 4 · - under the action of PMS and PDS (Equations 25 and 26). During the oxidation process, the reaction between Fe3+ and pyrite can promote the circulation of Fe2+/Fe3+ and the release of Fe2+ to promote the production of S O 4 · -, and at the same time, · OH can be produced under the action of S O 4 · - (Equation 27, 28). It is worth noting that sulfide plays an important role in the activation oxidation process of pyrite, and Zhou et al. Emphasized the role of sulfur species as electron donors for PMS activation. Although Fe2+ on pyrite effectively activates PMS, the regeneration of Fe2+ and the subsequent activation of PMS are critically controlled by S 2 2 -[4][69].
$2 \mathrm{HSO}_{5}^{-}+\mathrm{FeS}_{2} \rightarrow 2 \mathrm{SO}_{4}^{·-}+2 \mathrm{OH}^{-}+\mathrm{Fe}^{2+}+2 \mathrm{~S}$
$2 \mathrm{~S}_{2} \mathrm{O}_{8}^{2-}+\mathrm{FeS}_{2} \rightarrow 2 \mathrm{SO}_{4}^{·-}+2 \mathrm{SO}_{4}^{2-}+\mathrm{Fe}^{2+}+2 \mathrm{~S}$
$\mathrm{SO}_{4}^{·-}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{SO}_{4}^{2-}+\cdot \mathrm{OH}+\mathrm{H}^{+}$
$\mathrm{SO}_{4}^{·-}+\mathrm{OH}^{-} \rightarrow \mathrm{SO}_{4}^{2-}+\cdot \mathrm{OH}$

3.2 Improvement of pyrite materials and enhancement of their catalytic oxidation ability

3.2.1 Removal of heavy metals by modified pyrite catalytic oxidation

Pyrite has been widely studied for its excellent performance in the treatment of heavy metal or metalloid pollution, but its inherent defects, such as small specific surface area of pyrite and easy agglomeration in the water environment, lead to its low reactivity and limited reaction sites, which seriously affect the application of pyrite in practical wastewater. In addition, pyrite exhibits excellent photocatalytic properties due to its surface chemistry, high light absorption coefficient (α>6×105cm-1), and suitable band gap (0.95 eV). Therefore, various modification methods of pyrite have become a hot research topic, mainly focusing on promoting the oxidation of pyrite by external conditions and enhancing the photocatalytic performance of composite materials.
The release of Fe2+ from pyrite oxidation corrosion under natural conditions produces various ROS at a slow rate, so the addition of Fe2+ can form Fe (Ⅲ)/Fe (Ⅱ) redox couple in the system, which effectively promotes the electron transfer and oxidation rate of pyrite. Wu et al. Studied the oxidation of As (Ⅲ) in water by using Fe2+ to enhance FeS2, and pointed out that the removal efficiency of As (T) and As (Ⅲ) in the FeS2-As(Ⅲ) system added with Fe2+ reached 76.7% and 85.5%, respectively, which was much higher than that of the single FeS2-As(Ⅲ) system (29.6% and 39.2%)[70]. The role of Fe2+ in activating oxygen to generate more ROS through electron transfer on the pyrite surface and its contribution to As (Ⅲ) oxidation was revealed. In addition, due to the semiconductor characteristics of pyrite, when light irradiates pyrite, photons can resonate with the available electrons inside the semiconductor, generating hole-electron pairs in the valence band of pyrite surface, which are oxidized by H2O and O2 to produce · OH and H2O2, which is also the determinant of photocatalyst activity[71]. The sulfur defect sites on the surface of pyrite make it produce more · OH than other semiconductors under illumination, showing excellent photocatalytic performance[11]. Guo Diman studied the mechanism of oxidation and removal of As (Ⅲ) by FeS2 under illumination, and pointed out that FeS2 would oxidize and dissolve to release a certain amount of dissolved Fe2+, and produce free radicals · OH to oxidize As (Ⅲ) through the photo-Fenton process of Fe2+/FeOH2+[72]. Table 2 summarizes the oxidation removal of heavy (like) metals in water by pyrite modified by the addition of other oxidants or by the combination of other materials.
表2 黄铁矿改性材料催化氧化去除重(类)金属

Table 2 Removal of heavy metals by oxidation of pyrite modified materials

Modification method Modification material Target metal Removal performance ref
Surface oxidized surface-oxidized pyrite Sb(Ⅲ) 0.4 mg/g 73
Enhanced oxidation Fe2++FeS2 As(Ⅲ) 10 mg/g 70
FeS2 + PMS As(Ⅲ) 5 mg/g 74
FeS2+UV As(Ⅲ) 13.3 mg/g 72
Loading Fe0/FeS2 As(Ⅲ) 1 mg/g 75
FeS2/NaClO As(Ⅲ) 2.5 mg/g 76

3.2.2 Catalytic Oxidation Degradation of Organic Pollutants by Modified Pyrite

Although various pyrite-mediated AOPs have been widely studied and applied to the treatment of organic wastewater, pyrite itself has some inherent defects.For example, insufficient surface activity, slow dissolution rate, limited efficiency of heterogeneous reaction at solid-liquid interface, easy oxidation of pyrite, and passivation of catalyst by iron oxide layer formed on the surface, which still have some problems in the treatment of organic pollutants. In order to further improve the reaction performance of the system, various appropriate modification methods are considered to be necessary, such as ball milling, material composite construction of heterogeneous structures, material loading, etc.
The preparation of nano-sized pyrite is considered to be a good method to increase its surface reaction sites. Fathinia et al. Used high-energy mechanical ball milling to prepare pyrite nanoparticles to degrade orange 7 (AO7). After 6 H of ball milling, the average particle size of pyrite was between 20 and 100 nm.When the initial AO7 concentration was 16 mg/L, the H2O2 concentration was 5 mmol/L, the catalyst dosage was 0. 5 G/L and the reaction time was 25 min, the maximum removal efficiency reached 96. 30%, which was much higher than that of the original pyrite (35%)[77]. Nanoparticles generally have higher specific surface area and surface energy than conventional materials, thus providing greater chemical reactivity.
In addition, due to the superior semiconducting properties of pyrite itself, the construction of heterostructures can be chosen to further improve the performance of pyrite-mediated AOPs through photocatalysis. For example, Gong et al. Constructed a heterogeneous photo-Fenton catalytic system by using FeS2/Fe2O3 and organic acid, and under visible light irradiation, FeS2/Fe2O3 could be successfully activated by irradiation to generate photogenerated carriers, which improved the degradation effect of CBZ[78]. The photoinduced support can react with various components in the AOPs system, such as FeS2, Fe3+, H2O, and O2, thereby promoting the generation of active oxidizing species, and the catalytic activity of pyrite in AOPs can be effectively improved by the assistance of photoirradiation[79].
The loading of engineered carbon materials is also considered to be a promising modification method. The abundant surface functional groups and adsorption sites on the surface of carbon materials can adsorb or even reduce iron ions, thus avoiding the passivation of pyrite before initiating Fenton reaction. Zhao et al. Accelerated the degradation of ciprofloxacin (CIP) by adding three kinds of carbon materials (activated carbon, biochar, carbon nanotubes) into the FeS2/H2O2 system, and the reaction rates were 8.28 times, 3.40 times and 3.37 times higher than that of pyrite alone, respectively[80]. It is pointed out that carbon materials concentrate organic pollutants at the solid-liquid interface through adsorption, which is beneficial to their catalytic degradation[81]. The addition of carbon materials promotes the reduction of Fe3+ to Fe2+ and the generation of · OH, and its superior electron transfer ability is beneficial to the generation of free radicals and Fe2+/Fe3+ cycle.
Table 3 summarizes the degradation of organic pollutants in water by catalytic oxidation of pyrite modified by the construction of material composites and heterostructures.
表3 改进型黄铁矿催化氧化降解有机物

Table 3 Modified pyrite catalytic oxidation degradation of organic compounds

Modification method Modification material Target metal Removal performance ref
Ball-milling Pyrite nanoparticles Acid orange 7 16 mg/g 77
nano-pyrite Sulfadiazine 10 mg/g 82
Heterostructure FeS2/Fe2O3+TA Carbamazepine 1.3 mg/g 78
TiO2/FeS2 Methylene blue 6.1 mg/g 83
Fe3O4@FeS2@C@MoS2 Tetracycline 12.5 mg/g 84
ZnCo2O4/MnO2/FeS2 Methyl orange 3.84 mg/g 85
FeS2/rGO Methylene blue 41.67 mg/g 86
FeS2-Fe1-xS Acid orange 7 15 mg/g 87
CuO-FeS2 Brilliant green 2 mg/g 88
Loading FeS2/H2O2+AC, BC, CNTS Ciprofloxacin 89 mg/g, 71 mg/g, 68 mg/g 80

4 Reduction and Catalytic Reduction of Pyrite

In addition to the generation of oxidizing free radicals, pyrite itself can also release reducing Fe and S species, which can reduce and fix heavy metals (mainly Cr (Ⅵ)), and as a suitable chemical reducing agent to deal with heavy metal pollution, it is of great significance for the study of heavy metal pollution control. In addition, some organic pollutants, such as halogenated organic compounds, nitrobenzene, etc., which are not suitable for reaction with iron oxides due to their hydrophobicity, can also be removed by reduction or catalytic reduction of pyrite. In the treatment of actual sewage, reduction and adsorption often exist at the same time to remove all kinds of pollutants in the water body.

4.1 Mechanism and Application of Pyrite Reduction and Catalytic Reduction

4.1.1 Reduction of Heavy Metals by Pyrite

In the past decades, a large number of studies have proved that pyrite can effectively remove heavy metal pollutants in water through reduction, mainly focusing on the reduction of Cr (Ⅵ)[89]. It is further removed by precipitation by converting the highly toxic and mobile compound state into a less toxic and less mobile state. Lin et al. Studied the reduction of Cr (Ⅵ) by pyrite[90]. The results show that the reduction rate of Cr (Ⅵ) is strongly dependent on the pH of the solution. The initial rate of Cr (Ⅵ) reduction decreased with the increase of pH when pH > 3.0, and increased with the increase of pH when pH < 3.0.
The reduction of Cr (Ⅵ) can be divided into two different stages. The first is the dissolution of pyrite under acidic conditions, which releases Fe2+ and S 2 2 - ions (Equation 29), all of which can reduce Cr (Ⅵ) to produce Cr (Ⅲ), Fe3+, and S O 4 2 - species (Equations 30, 31)[90]. In addition, pyrite can also directly adsorb Cr (Ⅵ) on the surface for electron transfer (Formula 32).
$\mathrm{FeS}_{2} \rightarrow \mathrm{Fe}^{2+}+\mathrm{S}_{2}^{2-}$
$3 \mathrm{~S}_{2}^{2-}+7 \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+50 \mathrm{H}^{+} \rightarrow 6 \mathrm{SO}_{4}^{2-}+14 \mathrm{Cr}^{3+}+25 \mathrm{H}_{2} \mathrm{O}$
$6 \mathrm{Fe}^{2+}+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+14 \mathrm{H}^{+} \rightarrow 2 \mathrm{Cr}^{3+}+6 \mathrm{Fe}^{3+}+7 \mathrm{H}_{2} \mathrm{O}$
$3 \mathrm{FeS}_{2}+5 \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+32 \mathrm{H}^{+} \rightarrow 10 \mathrm{Cr}^{3+}+2 \mathrm{Fe}(\mathrm{OH})_{3}+4 \mathrm{SO}_{4}^{2-}+13 \mathrm{H}_{2} \mathrm{O}$
The pyrite in the system can continue to reduce the Fe3+ to Fe2+,Fe2+ to reduce Cr (Ⅵ) again, thus ensuring the continuous reaction (Formula 33).
$\mathrm{FeS}_{2}+14 \mathrm{Fe}^{3+}+8 \mathrm{H}_{2} \mathrm{O} \rightarrow 15 \mathrm{Fe}^{2+}+2 \mathrm{SO}_{4}^{2-}+16 \mathrm{H}^{+}$
Then the adsorbed chromium ions form hydroxide precipitates or co-precipitates on the surface of pyrite (Formula 34, 35), and these corrosion products will be adsorbed on the surface of pyrite, effectively reducing the concentration of Cr (Ⅵ) in the aqueous solution[7]. The reaction process is shown in fig. 7.
Cr3++Fe3++6OH-→Cr(OH)3+Fe(OH)3
Cr3++(1-x)Fe3++3H2O→CrxFe(1-x)(OH)3+3H+
图7 黄铁矿还原Cr(Ⅵ)的机理图[91]

Fig.7 Mechanism of Cr(Ⅵ) reduction by pyrite[91]

4.1.2 Reduction of Inorganic Salts by Pyrite

In addition to its ability to remove heavy metals, pyrite can also be used as a barrier material in nuclear waste storage systems to hinder nuclide migration. It is suggested that pyrite, which is widespread and stable in geological environment, can reduce the strong mobility of high-valence redox-sensitive nuclides to low-valence nuclides with low mobility[92]. The presence of pyrite will consume part of the oxidants (such as O2 and Fe3+) in the groundwater, thus maintaining the nuclear waste storage system under reducing conditions. It has been proved that pyrite can reduce radionuclides such as Se (Ⅵ), which is helpful to ensure the safety of the nuclear waste storage system[93].
Deen et al. Studied the abiotic sequestration mechanism of Se (Ⅵ) and Se (Ⅳ) by natural pyrite. Compared with Se (Ⅵ), Se (Ⅳ) in the solution was removed better, and the removal rate reached 97% after 99 days[94]. The removal of Se (Ⅳ) is attributed to the adsorption of Se (Ⅳ) on pyrite and subsequent reduction to insoluble Se (0). Liu Hongfang et al. studied the removal of Se (Ⅵ) in groundwater by pyrite, and analyzed the adsorption surface by XPS. It was found that a new form of Se (Ⅳ) was formed on the surface of pyrite after the reaction and occupied a dominant position. It was speculated that the removal of Se (Ⅵ) in water by pyrite was mainly by reduction, accompanied by adsorption reaction[95]. Yu et al. Simulated the reduction reaction between pyrite and redox-sensitive radionuclides (U, Se, Tc and Np), and the results showed that pyrite had a significant reduction effect on high-valence radionuclides (U, Se, Tc and Np)[92].
The reaction can be roughly divided into two parts, the first is the adsorption of radionuclides on the surface of pyrite, and the dissolution of pyrite releases Fe2+ and S 2 2 - ions (Equation 29).These reduction-competent species can then react with the adsorbed high-valence radionuclide to reduce it to the low-valence nuclide, while the Fe2+ and S 2 2 - ions oxidize to the Fe3+ and S O 4 2 - species. The reaction process is shown in Fig. 8.
图8 黄铁矿还原非金属离子的机理图

Fig.8 Mechanism of reduction of non-metallic ions by pyrite

4.1.3 Catalytic Reduction of Organic Pollutants by Pyrite

As a commonly used natural mineral, pyrite has been proved to have the potential to reduce some organic pollutants in situ, for example, the hydrophobicity of halogenated organic compounds greatly limits the effective transfer of electrons, while pyrite, with its dual surface properties, namely hydrophobicity and hydrophilicity, is conducive to the enrichment of organic pollutants[96]. Zhang et al. Used natural pyrite to remove nitrobenzene, and the results showed that pyrite had a good removal effect on nitrobenzene[97]. When 30 G/L pyrite was used for 5 H, the removal efficiency of 20 mg/L nitrobenzene was close to 100%, and the removal capacity was about 2. 3 mg/G, and the acid-producing characteristics of pyrite ensured the acidic pH conditions required for the reaction in a wide pH range (pH = 3 ~ 11), thus maintaining the reduction degradation efficiency of nitrobenzene. Kriegman-King et al. Investigated the reactivity of pyrite for reductive degradation of CCl4, and found that when the concentration of pyrite was 1.2 – 1.4 mg/L and the temperature was 25 ° C, more than 90% of CCl4 could be converted within 12 – 36 d[98]. Zhang et al. Studied the degradation of p-chloroaniline by pyrite, and pointed out that the various reactive species (ROS) produced by pyrite were mainly the reduction of chloroaniline by · O 2 -[99].
The basic principle of pyrite reductive degradation of organic pollutants is to use redox sites to capture organic pollutants, thereby enhancing the transfer of electrons, mineralizing the pollutants, and transforming them into relatively or completely harmless products[100]. These heterogeneous reaction pathways are generally characterized by a surface-mediated rate-limiting step, with surface disulfide (S-S) groups having been proposed as electron donors in reductive dehalogenation reactions, pyrite acting as a mediator by surface electron transfer as an electron conductor, and degradation of organic pollutants achieved by direct electron transfer[101]. In the reaction, pyrite dissociates and releases dissolved Fe2+ and S 2 2 - ions as electron donors, while the organic pollutants in the system are electron-deficient and can be easily reduced by the electron donor pyrite to produce S O 4 2 - and Fe3+. The reduction reaction of organic matter in pyrite system is a process of electron movement, pyrite is oxidized and provides working electrons, and organic pollutants accept electrons and are reduced to different products[97]. The main mechanism of action is shown in Fig. 9.
图9 黄铁矿还原有机污染物的反应机理图

Fig.9 Reaction mechanism of pyrite reducing organic pollutants

4.2 Improvement of pyrite-based materials and enhancement of their reducibility

4.2.1 Removal of Heavy Metals by Improved Pyrite Reduction

Due to the small specific surface area and easy agglomeration of FeS2, its action sites are greatly limited, and there are some defects in practical application.Therefore, the removal of heavy metal pollutants, especially Cr (Ⅵ), through the synergistic effect with other materials has become a hot research topic, such as ball milling, element doping, construction of heterogeneous structures, material loading and so on.
Huang Haijun et al. studied the synergistic effect of pyrite and clay minerals in the treatment of wastewater containing Cr (Ⅵ), and pointed out that under the condition that the initial concentration of Cr (Ⅵ) was 50 mg/L (pH = 5 ~ 6, reaction time 12 H), the removal amount of Cr (Ⅳ) was enhanced to 14. 27 mg/G after adding sepiolite[102]. Tang et al. Prepared a new ball-milled FeS2/ biochar composite (BM-FeS2@BC) for chromium removal, and they pointed out that reduction, adsorption, and surface complexation were the main mechanisms for the removal of Cr (Ⅵ) by BM-FeS2@BC, in which 92.25% of Cr (Ⅵ) was removed by reduction precipitation, while only 8.75% was removed by adsorption/surface complexation[103].
In addition, because the semiconductor properties of pyrite have great potential in the field of photocatalysis, adding semiconductor materials with different band gap widths or strong oxidizing semiconductors to construct heterostructures is also one of the ways to greatly improve the photocatalytic performance of composite materials. Guo et al. Constructed a Z-type FeS2/Fe2O3 photocatalyst for the reduction of Cr (Ⅵ), and the improvement of the performance of the FeS2/Fe2O3 composite under simulated sunlight irradiation can be attributed to the effective separation and transfer of photogenerated carriers.This promoted the generation of species such as · OH, photogenerated electrons (e-) and · O 2 -, pointing out that e- species are the main active species in the reduction of Cr (Ⅵ), and   · O 2 - is also involved in the reduction of Cr (Ⅵ)[6].
Table 4 summarizes the reductive removal of heavy metal ions in water by pyrite, which is functionally regulated by compounding other materials and constructing heterogeneous structures to improve photocatalytic performance.
表4 黄铁矿改性材料还原去除重金属

Table 4 Removal of heavy metals by reduction with pyrite modified materials

Modification method Modification material Target metal Removal performance ref
Ball-milling BM-FeS2@BC Cr(Ⅵ) 134 mg/g 103
Element doping Ni-FeS2/FeS2 Cr(Ⅵ) 40 mg/g 104
Heterostructure FeS2/Fe2O3 Cr(Ⅵ) 37.5 mg/g 6
α-FeOOH/FeS2 Cr(Ⅵ) 25 mg/g 105
Loading FeS2+Sepiolite Cr(Ⅵ) 14.27 mg/g 102
FeS2/Fe0 Cr(Ⅵ) 16.67 mg/g 106
FeS2/biochar Cr(Ⅵ) 10 mg/g 107
pyrite-marcasite-magnetite Cr(Ⅵ) 50 mg/g 108

4.2.2 Removal of inorganic salts by improved pyrite reduction

Synthetic pyrite is mostly in the nanometer scale, which has the advantages of small particle size, large specific surface area and high reactivity, and the purity of the prepared pyrite particles is more than 98%. Liu et al. Prepared nano-sized pyrite particles by wet method, which had large specific surface area and high reaction capacity, and could remove about 95% of Se (Ⅳ) after 12 H of reaction (dosage was 20 mg/L)[109]. The results show that Se (Ⅳ) in solution prefers to combine with S 2 2 - as electron donor to reduce Se (Ⅳ) to insoluble Se (0) species.It is pointed out that the redox reaction is the main process for the removal of Se (Ⅵ) from pyrite in aqueous environment, and the adsorption reaction occurs at the same time. Charlet et al. Synthesized nano-pyrite/mica composites to study the reduction of selenite and arsenate[110]. On the contrary, they pointed out that whether FeS2 can control the reduction rate of Se (Ⅳ) depends not only on pH and redox potential, but also on the concentration of dissolved Fe2+. This is because Fe2+ can either be oxidized by Se (Ⅳ) or participate in iron selenite formation, both of which can significantly increase the reaction rate, in which surface S 2 2 - is oxidized to S0.

4.2.3 Catalytic Reduction of Organic Pollutants by Modified Pyrite

It has been proved that FeS2 can effectively promote the corrosion of Fe0 and release more iron ions, which has also been applied to the removal of organic pollutants. Ri et al. Prepared 1∶1 Fe0/FeS2 by ball milling method to simultaneously reduce DCNB (2,4-dichloronitrobenzene) with small-leaf alfalfa MR-1 and microbial mass (MC), and the removal rate of DCNB reached 100% after 6 H of reaction at the initial DCNB concentration of 20 mg/L, which was significantly higher than that of FeS2+MR-1 (62%)[111]. They believed that the improvement of reaction effect was mainly due to the rapid corrosion of Fe0/FeS2 in the reaction medium and the improvement of reaction activity, which greatly promoted the reduction of DCNB while producing FeS. The produced FeS has high electron conductivity, which strengthens the direct electron transfer to methanogens, resulting in the rapid production of methane.

5 Conclusion and prospect

Pyrite is widely available and cheap, and its special surface properties and stable crystal structure make it have good adsorption and redox capacity, which is widely used to treat heavy metal ions, inorganic salts and organic compounds in water, and shows great potential in the treatment of environmental pollutants. However, natural pyrite is easy to agglomerate and has insufficient surface reaction sites, so appropriate functional regulation and modification of pyrite has become a research hotspot. Synthetic pyrite has ideal morphology and particle size, which is more suitable for mechanism study than natural pyrite. The loading of engineering carbon materials can greatly reduce the agglomeration of pyrite. Element doping can effectively control the surface state, thereby changing the physical and chemical properties. Heterostructures with other highly conductive semiconductor materials have also made great progress in the field of photocatalysis. At present, natural pyrite and various synthetic and modified pyrite materials are widely used to deal with various environmental pollution problems, but their large-scale application is still limited, and they may be strengthened and developed in the following aspects:
(1) At present, many studies lack the treatment of large polluted water bodies, and the preparation of artificial pyrite materials is complex and the stability of materials is low. It is suggested to optimize the synthesis conditions and modification process of the materials, simplify the preparation method, reduce the time cost, reduce the secondary pollution, and develop efficient, economical and environmentally friendly materials. And focus on its application in the actual environment to achieve mass production.
(2) The characterization techniques and computational methods used in the existing studies are not perfect enough to fully reveal the reaction mechanism at the molecular level. It is suggested that the follow-up study can be further deepened from the perspective of mechanism, and the theoretical calculation and model fitting can be reasonably used to explore the material system and analyze its reaction mechanism, so as to improve the selectivity and treatment performance of the material for pollutants.
(3) Most of the current studies focus on the treatment of one or two pollutants, which can not effectively deal with the complex situation containing multiple types of pollutants, and the selective treatment capacity of pollutants is insufficient, the pollutants adsorbed on the surface of pyrite lack subsequent treatment, and the material after reaction is difficult to separate from solid and liquid. It is suggested that the future research of environmental minerals should focus on the comprehensive utilization and modification of materials, give full play to the complementary characteristics of materials, and select appropriate control means and modification methods to improve the treatment capacity of pyrite in actual polluted water.

References

Publishing order | Descend order by publishing year | Descend order by cited within
[1]
Ji H Y, Peng D Z, Fan C T, Zhao K K, Gu Y, Liang Y Q. Urban Clim., 2022, 43: 101148.

[2]
Luo S X, Chen H S, Mou Q S, Wu Y H. Multipurpose Utilization of Mineral Resources, 2020, (05): 27.

(罗宿星, 陈华仕, 牟青松, 伍远辉. 矿产综合利用, 2020, (05): 27.).

[3]
Han D S, Song J K, Batchelor B, Abdel-Wahab A. J. Colloid Interface Sci., 2013, 392: 311.

[4]
Song B, Zeng Z T, Almatrafi E, Shen M C, Xiong W P, Zhou C Y, Wang W J, Zeng G M, Gong J L. Water Res., 2022, 211: 118048.

[5]
Li Y K, Qi X J, Li G H, Wang H. Chem. Eng. J., 2021, 410: 128303.

[6]
Guo Q, Tang G B, Zhu W J, Luo Y M, Gao X Y. J. Environ. Sci., 2021, 101: 351.

[7]
Li Z F. Doctoral Dissertation of Shaoxing University, 2017.

(栗占锋. 绍兴文理学院博士论文, 2017.).

[8]
Wang Y. Doctoral Dissertation of Jilin University, 2022.

(王遥. 吉林大学博士论文, 2022).

[9]
Khabbaz M, Entezari M H. J. Environ. Manag., 2017, 187: 416.

[10]
Zheng X F, Pan X, Nie Z Y, Yang Y, Liu L Z, Yang H Y, Xia J L. Minerals, 2018, 8(9): 366.

[11]
Mashayekh-Salehi A, Akbarmojeni K, Roudbari A, Peter van der Hoek J, Nabizadeh R, Dehghani M H, Yaghmaeian K. J. Clean. Prod., 2021, 291: 125235.

[12]
Jiang K, Liu J, Wang Y, Zhang D J, Han Y X. Appl. Surf. Sci., 2023, 610: 155476.

[13]
Zhang X F, Fan H, Yuan J, Tian J, Wang Y F, Lu C L, Han H S, Sun W. J. Environ. Chem. Eng., 2022, 10(6): 108856.

[14]
Shi S, Wu Q Y, Li X Z, Huang M H. Environmental Science, 2020, 41(09): 4124.

(石松, 吴乾元, 李新正, 黄满红. 环境科学, 2020, 41(09): 4124.).

[15]
Yang Y J, Liu J, Liu F, Wang Z, Miao S. J. Hazard. Mater., 2018, 344: 104.

[16]
Borah D, Senapati K. Fuel, 2006, 85(12/13): 1929.

[17]
He Y. Doctoral Dissertation of University of South China, 2019.

(何叶. 南华大学博士论文, 2019.).

[18]
Bulut G, Yenial Ü, Emiroğlu E, Ali Sirkeci A. J. Clean. Prod., 2014, 84: 526.

[19]
Bostick B C, Fendorf S. Geochimica Cosmochimica Acta, 2003, 67(5): 909.

[20]
He X Y, Min X B, Peng T Y, Ke Y, Zhao F P, Sillanpää M, Wang Y Y. Environ. Sci. Pollut. Res., 2020, 27(14): 16484.

[21]
Hu G L. Doctoral Dissertation of Central China Normal University, 2022.

(胡国良. 华中师范大学博士论文, 2022.).

[22]
Gan M, Li J Y, Sun S J, Cao Y Y, Zheng Z H, Zhu J Y, Liu X X, Wang J, Qiu G Z. Chem. Eng. J., 2018, 341: 27.

[23]
Liu Y L, Wu S H, Liang Z S, Liu Y, Ren H T, Jia S Y, Han X. Chem. Geol., 2019, 522: 223.

[24]
Luo S X, Nie X, Yang M Z, Fu Y H, Zeng P, Wan Q. Minerals, 2018, 8(10): 428.

[25]
Gao R Q, Hu P W, Dai Y N, Zhang Y, Liu L, Yang W Z. Appl. Surf. Sci., 2022, 602: 154353.

[26]
Wang J, Chen T H, Li P, Xie J J, Ma B D, Cao Y G. Acta Mineralogica Sinica, 2012, 32(02): 238.

(王菊, 陈天虎, 李平, 谢晶晶, 马炳德, 曹光跃. 矿物学报, 2012, 32(02): 238.).

[27]
Abdullah N H, Xian O J, Yi C Z, Yuan N S, Yaacob M S S, Salim N a A, Ahmad N, Lazim Z M, Nuid M, Abdullah F. Biointerface Research in Applied Chemistry, 2023, 13(1), 56.

[28]
Zhang J, Li R H, Li J, Liu B. Chinese Journal of Environmental Engineering, 2013, 7(10): 3856.

(张菁, 李睿华, 李杰, 刘波. 环境工程学报, 2013, 7(10): 3856.).

[29]
Pang Y M, Wang J L. Bioresour. Technol., 2020, 318: 124105.

[30]
TorrentÓ C, Urmeneta J, Otero N, Soler A, Viñas M, Cama J. Chem. Geol., 2011, 287(1/2): 90.

[31]
Wang D, Liu H F, Qian T W. Environmental Pollution & Control, 2014, 36(03): 30.

(王丹, 刘宏芳, 钱天伟. 环境污染与防治, 2014, 36(03): 30.).

[32]
Bostick B C, Fendorf S, Helz G R. Environ. Sci. Technol., 2003, 37(2): 285.

[33]
Pu J Y, Feng C P, Liu Y, Li R, Kong Z, Chen N, Tong S, Hao C B, Liu Y. Bioresour. Technol., 2014, 173: 117.

[34]
Tong S, Stocks J L, Rodriguez-Gonzalez L C, Feng C P, Ergas S J. Bioresour. Technol., 2017, 244: 296.

[35]
Li R H, Yuan Y L, Zhan X M, Liu B. Environ. Sci. Pollut. Res., 2014, 21(2): 972.

[36]
Galvez-Martinez S, Mateo-Marti E. Life, 2018, 8(4): 50.

[37]
Fang Y F, Li X Y, Zhou W, Wang X W, Cai K, Jia M K, Huang Y P. Environ. Chem., 2014, 33(11): 1941.

(方艳芬, 李新玉, 周薇, 王小维, 蔡宽, 贾漫珂, 黄应平. 环境化学, 2014, 33(11): 1941.).

[38]
Cai K, Xiong S W, Zhang X X, Li R P, Huang Y P. Acta Petrologica et Mineralogica, 2014, 33(02): 370.

(蔡宽, 熊世威, 张欣欣, 李瑞萍, 黄应平. 岩石矿物学杂志, 2014, 33(02): 370.).

[39]
Hu J S, Li R H, Sun Q Q, Liu Z, Zhang X M. Chinese Journal of Environmental Engineering, 2015, 9(11): 5463.

(胡俊松, 李睿华, 孙茜茜, 刘卓, 张小梅. 环境工程学报, 2015, 9(11): 5463.).

[40]
Wang Z H, Xie X H, Xiao S M, Liu J S. Hydrometallurgy, 2010, 102(1/4): 87.

[41]
Han G, Wen S M, Wang H, Feng Q C. Sep. Purif. Technol., 2020, 240: 116650.

[42]
Pourghahramani P, Akhgar B N. J. Ind. Eng. Chem., 2015, 25: 131.

[43]
He X Y, Min X B, Peng T Y, Ke Y, Zhao F P, Wang Y Y, Sillanpää M. J. Chem. Eng. Data, 2019, 64(12): 5910.

[44]
Huang S J. Doctoral Dissertation of Guangdong University of Technology, 2017.

(黄树杰. 广东工业大学博士论文, 2017.).

[45]
Qi L Q, Wang X, Wang W, Li J X, Huang Y. Environ. Sci. Pollut. Res., 2022, 29(26): 39228.

[46]
Cui J Y. Doctoral Dissertation of Taiyuan University of Science and Technology, 2016.

(崔晋艳. 太原科技大学博士论文, 2016.).

[47]
Zhang W, Huang F Y, Hu W W. Environ. Sci. Pollut. Res., 2020, 27(29): 36816.

[48]
Kong Z, Song Y Q, Shao Z Y, Chai H X. Water Res., 2021, 206: 117737.

[49]
Li H B, Li Y F, Guo J B, Song Y Y, Hou Y N, Lu C C, Han Y, Shen X F, Liu B W. Environ. Res., 2021, 194: 110708.

[50]
Lian J J, Xu S G, Zhang Y M, Han C W. Water Sci. Technol., 2013, 67(8): 1859.

[51]
Fornaro T, Boosman A, Brucato J R, ten Kate I L, Siljeström S, Poggiali G, Steele A, Hazen R M. Icarus, 2018, 313: 38.

[52]
Galvez-Martinez S, Escamilla-Roa E, Zorzano M P, Mateo-Marti E. Appl. Surf. Sci., 2020, 530: 147182.

[53]
Li Y Y, Liang J L, He X, Zhang L, Liu Y S. J. Hazard. Mater., 2016, 320: 216.

[54]
Gadisa B T, Appiah-Ntiamoah R, Kim H. Environ. Sci. Pollut. Res., 2019, 26(3): 2734.

[55]
Zhang P, Yuan S H. Geochimica Cosmochimica Acta, 2017, 218: 153.

[56]
Liu L H, Guo D M, Ning Z P, Liu C S, Qiu G H. Water Res., 2021, 203: 117545.

[57]
Fu F L, Wang Q. J. Environ. Manag., 2011, 92(3): 407.

[58]
Vidu R, Matei E, Predescu A M, Alhalaili B, Pantilimon C, Tarcea C, Predescu C. Toxics, 2020, 8(4): 101.

[59]
Kong L H, Hu X Y, He M C. Environ. Sci. Technol., 2015, 49(6): 3499.

[60]
Yan L, Chan T S, Jing C Y. Environ. Pollut., 2020, 262: 114309.

[61]
Sun F L, Dempsey B A, Osseo-Asare K A. J. Colloid Interface Sci., 2012, 388(1): 170.

[62]
Zhao L H, Chen Y F, Liu Y X, Luo C, Wu D L. Chemosphere, 2017, 188: 557.

[63]
Yu F K, Wang Y, Ma H R, Zhou M H. Sep. Purif. Technol., 2020, 248: 117022.

[64]
Ammar S, Oturan M A, Labiadh L, Guersalli A, Abdelhedi R, Oturan N, Brillas E. Water Res., 2015, 74: 77.

[65]
Barhoumi N, Oturan N, Olvera-Vargas H, Brillas E, Gadri A, Ammar S, Oturan M A. Water Res., 2016, 94: 52.

[66]
Rahimi F, van der Hoek J P, Royer S, Javid A, Mashayekh-Salehi A, Jafari Sani M. J. Water Process. Eng., 2021, 40: 101808.

[67]
Nichela D A, Donadelli J A, Caram B F, Haddou M, Rodriguez Nieto F J, Oliveros E, García Einschlag F S. Appl. Catal. B Environ., 2015, 170/171: 312.

[68]
Zhang P, Huang W, Ji Z, Zhou C G, Yuan S H. Geochimica Cosmochimica Acta, 2018, 238: 394.

[69]
Zhou Y, Wang X L, Zhu C Y, Dionysiou D D, Zhao G C, Fang G D, Zhou D M. Water Res., 2018, 142: 208.

[70]
Wu X J, Yang J M, Liu S Y, He Z W, Wang Y Y, Qin W X, Si Y B. Chemosphere, 2022, 309: 136793.

[71]
Crundwell F K. Miner. Eng., 2021, 161: 106728.

[72]
Guo D M. Doctoral Dissertation of Huazhong Agricultural University, 2021.

(郭迪满. 华中农业大学博士论文, 2021.).

[73]
Wang W T, Zhang C J, Shan J, He M C. Chem. Geol., 2020, 552: 119790.

[74]
Fu D, Kurniawan T A, Lin L, Li Y Q, Avtar R, Dzarfan Othman M H, Li F. J. Environ. Manag., 2021, 286: 112246.

[75]
Du M M, Zhang Y Q, Hussain I, Du X D, Huang S B, Wen W. Chemosphere, 2019, 233: 744.

[76]
Lee D W, Ahn Y, Cho D W, Basak B, Jeon B H, Choi J. Environ. Pollut., 2023, 317: 120681.

[77]
Fathinia S, Fathinia M, Rahmani A A, Khataee A. Appl. Surf. Sci., 2015, 327: 190.

[78]
Gong C, Zhai J L, Wang X, Zhu W J, Yang D L, Luo Y M, Gao X Y. Chemosphere, 2022, 307: 136199.

[79]
Xu C X, Kong Y L, Zhang W J, Yang M D, Wang K, Chang L, Chen W, Huang G B, Zhang J. Sep. Purif. Technol., 2022, 303: 122266.

[80]
Zhao B C, Gong J L, Song B, Sang F, Zhou C Y, Zhang C, Cao W C, Niu Q Y, Chen Z P. Chemosphere, 2022, 308: 136427.

[81]
Luo K, Pang Y, Wang D B, Li X, Wang L P, Lei M, Huang Q, Yang Q. J. Environ. Sci., 2021, 108: 201.

[82]
Shi X G, Ma K, Gu Y W, Zhang W Q, Sun J. Sep. Purif. Technol., 2022, 292: 121060.

[83]
Rashid J, Saleem S, Awan S U, Iqbal A, Kumar R, Barakat M A, Arshad M, Zaheer M, Rafique M, Awad M. RSC Adv., 2018, 8(22): 11935.

[84]
Deng X H, Yang Y, Mei Y Q, Li J Q, Guo C L, Yao T J, Guo Y M, Xin B F, Wu J. J. Alloys Compd., 2022, 901: 163437.

[85]
Subhiksha V, Alatar A A, Okla M K, Alaraidh I A, Mohebaldin A, Aufy M, Abdel-Maksoud M A, Raju L L, Thomas A M, Khan S S. Chemosphere, 2022, 303: 135177.

[86]
Zhang F L, Liu J X, Yue H R, Cheng G J, Xue X X. Vacuum, 2021, 192: 110433.

[87]
Guo X J, Jia J L, Xu Y N, Meng Q, Zha F, Tang X H, Tian H F. Appl. Surf. Sci., 2021, 556: 149786.

[88]
Raju A G, Rao B D, Himabindu G, Botsa S M. J. Mater. Res. Technol., 2022, 17: 2648.

[89]
Wang H H, Lei W, Li X J, Huang Z, Jia Q L, Zhang H J. Progress in Chemistry, 2021, 32(12): 1990.

(王洪红, 雷文, 李孝建, 黄仲, 贾全利, 张海军. 化学进展, 2021, 32(12): 1990.).

[90]
Lin Y T, Huang C P. Sep. Purif. Technol., 2008, 63(1): 191.

[91]
Nie X, Li G Y, Wang Y, Luo Y M, Song L, Yang S G, Wan Q. J. Hazard. Mater., 2022, 424: 127504.

[92]
Yu H Q, Yu T, Zeng K. Front. Environ. Sci., 2022, 10: 955519.

[93]
Kang M L, Chen F R, Wu S J, Yang Y Q, Bruggeman C, Charlet L. Environ. Sci. Technol., 2011, 45(7): 2704.

[94]
Deen S G, Hendry M J, Lee Barbour S, Das S, Essilfie-Dughan J. Geochemistry, 2022, 82(1): 125863.

[95]
Liu H F, Qian T W, Zhang M G. Spectroscopy and Spectral Analysis, 2015, 35(02): 543.

(刘宏芳, 钱天伟, 张敏刚. 光谱学与光谱分析, 2015, 35(02): 543.).

[96]
Li P. Doctoral Dissertation of Hefei University of Technology, 2016.

(李平. 合肥工业大学博士论文, 2016.).

[97]
Zhang Y L, Zhang K, Dai C M, Zhou X F. Chem. Eng. Sci., 2014, 111: 135.

[98]
Kriegman-King M R, Reinhard M. Environ. Sci. Technol., 1994, 28(4): 692.

[99]
Zhang Y Q, Tran H P, Hussain I, Zhong Y Q, Huang S B. Chem. Eng. J., 2015, 279: 396.

[100]
Rahim H U, Qaswar M, Wang M L, Jing X D, Cai X Y. J. Environ. Chem. Eng., 2021, 9(6): 106696.

[101]
Cheng J, Yuan J, Li S Y, Yang X L, Lu Z J, Xu J M, He Y. Crit. Rev. Environ. Sci. Technol., 2022, 52(14): 2582.

[102]
Huang H J, Chen J Y, Wang X F. Modern Mining, 2021, 37(04): 176.

(黄海军, 陈金毅, 王小凤. 现代矿业, 2021, 37(04): 176.).

[103]
Tang J C, Zhao B B, Lyu H H, Li D. J. Hazard. Mater., 2021, 413: 125415.

[104]
Liu C R, Xiao H, Liu Y, Li D J, He H, Huang X H, Shen W T, Yan Z Y, Dang Z, Zhu R L. J. Colloid Interface Sci., 2023, 629: 847.

[105]
Guo Y D, Li C X, Gong Z H, Guo Y P, Wang X G, Gao B, Qin W J, Wang G H. J. Hazard. Mater., 2020, 397: 122580.

[106]
Yang W C, Li X M, Xi D D, Li Q, Yang Z H, Min X B, Lin Z, Liao Q. Chemosphere, 2021, 281: 130957.

[107]
Zhao B B, Tang J C, Lyu H H, Liu F, Wang L. J. Environ. Chem. Eng., 2022, 10(2): 107181.

[108]
Lin Y T, Li J F, Chen S Y, Zhou H D, Shu Y M, Tang L Q, Long Q, Zhang P C, Huang Y. Sep. Purif. Technol., 2023, 308: 122764.

[109]
Liu H F, Qian T W, Zhang M G. Spectroscopy and Spectral Analysis, 2015, 35(2): 543.

[110]
Charlet L, Kang M L, Bardelli F, Kirsch R, GÉhin A, Grenèche J M, Chen F R. Environ. Sci. Technol., 2012, 46(9): 4869.

[111]
Ri C, Li F X, Mun H, Liu L N, Tang J C. Chem. Eng. J., 2023, 452: 139086.

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