Nickel-cobalt solvent extraction wastewater contains high salt and high organic pollutants,organic pollutants not only caused chemical oxygen demand(COD)to exceed the emission standard of pollutants,but also caused enormous problems such as generating a lot of foam,emerging difficulty in crystallization and producing waste crystalline salt in the evaporative crystallization process of wastewater,which seriously restricts the near-zero discharge of nickel-cobalt solvent extraction wastewater.In this study,the relationship between the structure and adsorption performance of macroporous resins(MARs)was explored by comparing the microstructure of four typical MARS and their adsorption capacity for organic pollutants in the nickel-cobalt solvent extraction wastewater.The study found that ORZ-A2 had the best adsorption capacity of organic pollutants and the single-stage static adsorption removal rate of total organic carbon(TOC)and total phosphorus(TP)were 70.79％and 83.11％respectively,which might be attributed to the reasonable pore size distribution and large specific surface area.Further,GC-MS was used to characterize the composition of organic pollutants of raw wastewater and adsorbed wastewater by MARs.It was found that the organic pollutants in nickel-cobalt solvent extraction wastewater were mainly organophosphorus extractants,their hydrolysates and derivatives represented by 2-ethyl-hexanoic acid.The four types of MARs had good adsorption effects on organophosphorus extractant and 2-ethyl-hexanoic acid,however,the organic pollutant in the adsorbed wastewater was mainly valeric acid,which indicated that the water-soluble small molecular organic pollutants represented by valeric acid might be the key to further enhance the removal rate of TOC.Subsequently,the kinetics study found that organic pollutants uptake onto four MARs followed the pseudo-second order model.The calculation results of thermodynamic parameters indicated that the adsorption of organic pollutants on MARs was a spontaneous,and exothermic physical adsorption process.This work provides a theoretical basis for guiding the industrial application of MARs adsorption technology for organic pollutants in nickel-cobalt solvent extraction wastewater.
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