Study On Degradation Of Butyl Xanthate By Persulfate Activation With Carbon Cobalt Composite Catalyst

Mineral processing engineering occupies an important strategic position in the development of China’s national economy.A large amount of sulphide ores need to be treated by froth flotation in China every year,consuming an extremely large amount of mineral processing chemicals.Xanthate,which is highly toxic and difficult to biodegrade,has become a priority pollutant of water in mining area.And there was an urgent need to solve the environmental problems caused by the discharge of xanthate wastewater in an efficient and rapid manner.Persulfate oxidation technology has become a research hotspot in recent years due to its strong oxidizability,no secondary pollution,high treatment efficiency.The carbon aerogel with excellent structure and performance as an activator for persulfate has also attracted much attention.In this study,we introduced the degradation of xanthate by unactivated persulfate,prepared carbon cobalt composite catalysts with high catalytic activity and easy recovery,focused on reviewing the applicability and durability of carbon cobalt catalysts in persulfate systems,revealed oxidation mechanisms and reaction pathways for xanthate degradation.Finally,toxicity assessment was conducted on the treated xanthate wastewater,and the catalyst was applied to actual wastewater treatment,provided technical support and theoretical guidance for the development of new carbon cobalt catalysts and the efficient treatment of mineral processing wastewater.（1）In this thesis,the commonly used flotation agent butyl xanthate（BX）was used as the target pollutant.It was found that the unactivated peroxymonosulfate（PMS）could efficiently degrade BX.2 mmol/L of PMS could completely degrade BX within15 min,whereas peroxysulphate（PDS）had a limited effect on BX,with the same dose of PDS only degrading 14.6%of BX within 60 min.The BX degradation behavior of individual PMS was a non-radical dominated process,which can adapt to a wide p H value range and was basically unaffected by impurity ions and natural organic compounds,demonstrating great potential for application in wastewater treatment.However,the mineralization degree of PMS to BX is limited.Excessive PMS could mineralize 39%of BX,while adding Fe²⁺could effectively increase the mineralization degree of BX to 79.3%.（2）Using agar and sodium alginate as raw materials,which can form eggshell structure by complexing with multivalent metal ions to introduce Co²⁺,a double network aerogel crosslinked by agar,sodium alginate and cobalt was prepared.After high-temperature carbonization,a carbon cobalt composite catalyst with cobalt particles uniformly embedded in the carbon network is obtained to efficiently activate persulfate.By adjusting the ratio of raw materials and pyrolysis temperature to control the catalytic performance of the catalyst,the Co@C800-1 with the highest Co atom loading of 15.07%was obtained under the conditions of 1:1 raw material ratio and a pyrolysis temperature of 800?C.The degradation degree of BX was 96.6%and 100%when the dosage of Co@C800-1 was 0.15 g/L,and the concentrations of PMS and PDS were 0.25 mmol/L and 1.0 mmol/L,respectively.The Co@C800-1 could still maintain over 90%catalytic activity after multiple cycles in two persulfate systems,demonstrating its great stability.（3）The activation mode of Co@C800-1 in two persulfate systems was investigated.The activation mechanism of Co@C800-1/PMS and Co@C800-1/PDS systems was revealed by EPR radical detection,radical quenching experiments and characterization of structure and properties of Co@C800-1 before and after reaction.The Co@C800-1/PMS system was mainly based on non free radical pathways,with¹O₂ as the main active species,while the Co@C800-1/PDS system was mainly based on free radical pathways,with SO₄^·-和·OH as the main active species.The multivalent Co particles on the Co@C800-1 surface,carbon layer surface defects,and oxygen-containing functional groups were all used as the active site of the Co@C800-1 for the activation of persulfate with high efficiency,which could significantly reduce the toxicity of BX wastewater and effectively degrade the actual wastewater.