Study On Advanced Oxidation Behavior Of Modified Electrolytic Manganese Slag Catalyst In Degradation Reagent Of Mineral Processing

In the process of mineral processing,foam flotation is a common technology.Flotation reagents can be used in this process to enhance the mineral extractability.Ammonium butylammonium dithiophosphate（ADD）and terpineol oil（TP）are the traditional mineral flotation agents widely used in beneficiation mining.However,if the wastewater containing residual flotation agents is discharged into the environment,it will continue to accumulate and eventually become a threat to the ecosystem and human beings.Therefore,an effective and feasible process is urgently needed to treat ADD and TP in mineral processing wastewater.Persulfate-based advanced oxidation processes（SR-AOPs）have attracted attention due to their high efficiency.However,the existing catalysts have the shortcoming of high cost and toxicity,as well as difficult recovery.Manganese slag（MS）contains rich transition metals,which can be used to prepare SR-AOPS catalysts.In this study,high value MS and coupled SR-AOPs technology were used to remove organic pollutants from mineral processing wastewater.The main research contents and conclusions are as follows:（1）A catalyst（MS-H₂SO₄）was prepared by a simple modification method to remove impurities on MS surface and improve the specific surface area of MS.MS-H₂SO₄can activate peroxo monosulfate（PMS）to generate SO₄^·-、·OH、O₂^·-and ¹O₂to promote the degradation of ADD,with a degradation rate of 83.6%within30 min.However,the stability and reusability of MS-H₂SO₄need to be improved.（2）A high efficiency PMS activator（MS-NMN）was prepared by modifying MS with ammonia and sodium carbonate to remove a large number of impurities and expose the active sites of Fe and Mn.The degradation rate of ADD in MS-NMN/PMS system reached 95.7%within 30 min.In MS-NMN/PMS system,SO₄^·-、·OH、O₂^·-and¹O₂are generated,but SO₄^·-and·OH do not participate in the degradation of ADD,while O₂^·-and ¹O₂are important reactive oxygen species（ROS）for degradation of ADD in MS-NMN/PMS system.MS-NMN has good pH adaptability,stability and reusability.（3）Although MS-NMN catalyst can effectively remove ADD,it cannot effectively degrade TP and other substances with high ionic potential.Therefore,the optimum preparation temperature was determined by changing the preparation conditions.The catalyst MS-NMN₁₅₀prepared at 150℃could degrade the TOC in the solution by 58.6%within 2h.The REDOX cycles of Mn（Ⅲ）/Mn（Ⅱ）、Mn（Ⅳ）/Mn（Ⅲ）and Fe（Ⅲ）/Fe（Ⅱ）promote the formation of SO₄^·-,which is further converted to·OH.The mixed metal valences combine with the abundant-OH groups on the surface as the activation sites to accelerate the decomposition of PMS.