Study On The Advanced Oxidation Removal Of Flotation Reagents By Catalysts Prepared With Electrolytic Manganese Residues

Sulfate-based advanced oxidation processes（SR-AOPs）are widely used in the removal of organic pollutants due to their high oxidative performance and ease of operation.But they require expensive/toxic chemical precursors due to the complex preparation process,which greatly hinders their large-scale applications.Electrolytic manganese residues（EMR）are rich in manganese and iron oxides,which can be used as a substitute for traditional AOPs metal-based catalysts.However,EMR contains a large number of impurities such as Ca and Mg oxides,which greatly affects the activation performance of EMR as a catalyst.Therefore,this work aimed at seeking an efficient technology for organic pollutants removal in beneficiation based on the resource utilization of EMR.Then,it was systematically studied on the degradation behavior and mechanism of EMR-based systems on typical flotation reagents（dithionitride（DDTC）,butyl xanthate（BX）,ester-200（Z-200）,butylamine（BA）,terpineol oil and benzohydroxamic acid（BHA））.This study could provide technical support and a theoretical basis for the realization of EMR utilization and removal of organic pollutants from beneficiation wastewater.The main research contents and conclusions are as follows:（1）EMR was directly prepared into a bimetallic catalyst（MS-N3H）through a short-cut modification method.By this way,the unfavorable components such as calcium and magnesium were removed,and the ratio of iron and manganese active components increased,which could effectively activate peroxymonosulfate（PMS）for fast removal of thiol collectors（DDTC,BX,Z-200 and BA）.MS-N3H/PMS system could produce a large amount of SO₄^·-,·OH,O₂^·-and ¹O₂,while the removal rates of BX and DDTC reached 99%within 10 min,and the removal rates of Z-200 and BA within 30 min were 92%and 86%,respectively.The degradation difference of the system to these thiol collectors mainly depended on the difference in molecular structures.The degradation difference of DDTC,BX and Z-200 is related to the HOMO index of S and N atoms in the molecule because they contain the same C=S functional group,and the targets with different functional groups are related to the molecular orbital energy（E）.The larger the E,the harder to be degraded.（2）Although MS-N3H could effectively remove thiol collectors,it could not effectively degrade substances with high plasma potential such as terpineol oil.Therefore,the phase of EMR was adjusted by roasting,and the impurity components on the surface of EMRx were cleaned by acid treatment to obtain a ternary composite catalyst（t-EMRx）with high degradation performance.The ternary composite catalyst was composed by Fe OOH,Fe₂O₃ and(Fe_0.67Mn_0.33)OOH composite.The t-EMRx/PMS system could remove 76.7%of terpineol oil within 90 min.SO₄^·-,·OH and ¹O₂ were all involved in the decomposition of terpineol oil,among which·OH played a major role.Under alkaline conditions,the-OH functional group was crucial for the conversion between SO₄^·-and·OH.Mn in the Fe OOH structure replaced Fe,which enriched the catalyst with O_V and enhanced the interfacial electron transfer,thereby accelerating the reduction of Fe^III to Fe^II and further improving the degradation efficiency.（3）The metal-carbon composite material has excellent properties.Therefore,an iron-manganese supported carbon composite（Fe/C-Mn）was synthesized successfully via“one-pot mixing”and pyrolysis modification method with EMR and sludge（SS）.Fe/C-Mn₈₀₀/PMS could remove 95.6%of BHA（20 mg/L）in aqueous solution within 60 min.The surface properties and electronic configuration of Fe/C-Mn could be regulated by transition metals（Fe,Mn）,persistent free radicals（PFRs）and graphitic nitrogen.The hierarchical porous structure of the N-containing carbon matrix facilitated the large adsorption of BHA and promoted the surface ternary active complex（PMS/Fe/C-Mn/BHA）.The single-electron and double-electron transfer pathways were carried out simultaneously to complete the decomposition of BHA.Additionally,Fe/C-Mn₈₀₀/PMS system had certain TOC and metal removal efficiencies for different BHA-metal complex pollutants.It was found that the removal rate of TOC was related to theΔG value of the complex.Mechanism exploration found that C=O and-OH plaid an important role in the degradation of organic matter,while Si-O/Si-O-Si,C-C and C=O participated in metal adsorption.（4）The study found that the Fe/C-Mn₈₀₀/PMS system had a better removal ability of COD in wastewater than both MS-N3H/PMS and t-EMR800/PMS system.The removal rate of COD in sulfide ore wastewater by different systems was higher than that of oxidized ore.The same trend also appeared when H₂O₂ was used as the oxidant.This work can provide strong technical support and theoretical basis for realizing the resource utilization of EMR and the removal of beneficiation organic pollutants in the environment.