Preparation Of Pyrite Cinder-Based Composite Photo-Fenton And Photocatalytic Materials And Their Degradation Performance For Antibiotics

Solar driven advanced oxidation process（AOPs）has certain advantages in dealing with antibiotic pollution,and it is crucial to design and develop a cost-effective and stable photo-Fenton or photocatalyst materials.In this paper,the abundant pyrite cinder（PyC）was used as the raw material,and the visible-light driven photo-Fenton and photocatalyst based on PyC were successfully prepared by hydrochloric acid leaching,modification and loading of active substances.Its structure and morphology were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and BET specific surface analysis.The catalytic degradation performance of ciprofloxacin（CIP）,tetracycline（TC）and sulfadiazine（SD）,and the degradation mechanism of their catalytic degradation of organic pollutants was preliminarily discussed.The controllable leaching of PyC was carried out with hydrochloric acid solution,and the optimal leaching process conditions were determined as follows:the concentration of hydrochloric acid was 25.3%,the dosage coefficient of hydrochloric acid was 0.67,the leaching temperature was 80°C and the leaching time was 2 h.Under these conditions,the leaching rate of Fe was 56.8%,and the remaining pyrite cinder（m-PyC）had a relatively uniform porous structure,and the main component was hematite Fe₂O₃.The composite photo-Fenton catalyst（m-PyC/Fe OCl）was prepared by calcination method using the ferric chloride solution obtained by leaching as the Fe source and the remaining porous cinder m-PyC as the carrier.Among them,the Fe OCl nanosheets in m-PyC/Fe OCl-43%are uniformly supported in the porous structure of m-PyC,and the adsorption-desorption isotherm belongs to the IV-type nitrogen adsorption-desorption curve of porous materials in the IUPAC classification,with H3-type hysteresis loop,and its specific surface area and average pore size are 4.90 m²/g and 8.10 nm,respectively.The band gap（E_g）of m-PyC/Fe OCl-43%is 1.80 e V,the photo-Fenton performance is significantly higher than that of pure Fe OCl and m-PyC,and it has a wide suitable p H range（3-7）.When the dosage of m-PyC/Fe OCl-43%was 1000 mg/L and the dosage of H₂O₂was 5 mmol/L,under visible-light irradiation for 60 min,the removal rates of CIP,TC and SD were 96.5%,99.1%and 89.9%,then TOC removal rates reached 72.4%,83.3%and 70.8%.The main active species in the degradation process were·OH and h⁺.In addition,m-PyC/Fe OCl-43%also has good separation,recovery,and recycling performance.According to the properties of different energy bands about Mn-doped BiFeO₃（BMFO）doped with different proportions of Mn,m-PyC/BMFO composites photocatalyst with adjustable energy bands were successfully prepared by coprecipitation-calcination method using m-PyC as carrier and leaching solution as Fe source.The adsorption-desorption isotherms of m-PyC/BMFO-5%（5%Mn doping in BiFeO₃）belong to the IV-type nitrogen adsorption-desorption curves of porous materials in the IUPAC classification,with H3-type hysteresis,and its specific surface area and average pore size were 14.98 m²/g and 11.20 nm,respectively.When the dosage of m-PyC/BMFO-5%was 1000 mg/L,the removal rates of CIP,TC and SD reached 96.4%,99.2%and 90.1%,after 120 min of visible-light irradiation,then the TOC removal rates reached 77.4%,88.6%and 70.7%.In m-PyC/BMFO-5%,BMFO-5%and m-PyC form a type II heterojunction,and its E_gis 1.95 e V;the main active species generated during the catalytic degradation process are·OH and h⁺which was mainly.m-PyC/BMFO-5%also has excellent recycling performance.Visible-light responsive Fe-doped Bi₂O₂CO₃（BFOC）was successfully prepared by a simple hydrothermal method using the leaching solution as the doping Fe source,and the m-PyC/BFOC composite photocatalyst was prepared by a one-pot hydrothermal method using m-PyC as the carrier.Among them,the BFOC sheet-like structure in m-PyC/BFOC-50%is uniformly supported in the pores of m-PyC,and its adsorption-desorption isotherm belongs to theⅣ-type nitrogen adsorption-desorption curves of porous materials in the IUPAC classification,with H3-type hysteresis loop.Its specific surface area and average pore size are 41.57 m²/g and 9.38 nm,respectively.m-PyC/BFOC-50%showed better adsorption performance for CIP,TC and SD,and the maximum adsorption capacities at 25°C were 11.52,23.95 and 6.40 mg/g,respectively.When the dosage of m-PyC/BFOC-50%was 1000 mg/L,the removal rate of CIP,TC and SD reached 97.3%,99.3%and 90.1%under visible-light irradiation for 120 min,then the TOC removal rates reached 75.2%,91.0%and 79.6%.In m-PyC/BFOC-50%,BFOC and m-PyC form a Z-type heterojunction.The E_gis 1.87 e V,which is slightly lower than that of m-PyC（1.92 e V）and significantly lower than that of Bi₂O₂CO₃（3.2-3.3 e V）,which effectively reduces the recombination rate of photogenerated carriers.The main active species in the photocatalytic degradation process were·OH and h⁺.m-PyC/BFOC-50%also showed excellent separation,recovery,and recycling performance.In conclusion,the above-mentioned photo-Fenton and photocatalytic materials prepared from PyC have a simple preparation method,low cost,excellent performance,and good separation,recovery,and recycling performance,and can be used for antibiotics pollution as a class of high-efficiency and low-cost catalytic materials by high-efficiency treatment and can also open a new way for the efficient and high-value-added resource utilization of PyC,which has broad application prospects.