Removal of xanthate from aqueous solutions by adsorption onto untreated and acid/base treated activated carbons

Xanthate is a widely common pollutant in wastewaters of mineral industries. The removal of ethyl xanthate (EX-), the most widely used xanthates in mineral industries, from aqueous solutions was studied by activated carbon adsorption as the clean and cost-effective industrial wastewater treatment technology. The characterization of activated carbon (AC) was performed by a point of zero charge determination, scanning electron microscopy, wavelength dispersive X-ray, surface area, and a pore size analyzer. The evaluation of initial solution concentration, pH, temperature, particle size, and surface chemistry of AC on the adsorption process showed that it is a high-potential adsorbent for xanthate removal. The study of EX- adsorption onto acid/base treated ACs revealed that the adsorption of EX- primarily occurs on non-polar carbon surface patches where it is driven by hydrophobic interactions. The equilibrium and kinetic data were best modeled by the Koble-Corrigan isotherm and fractional power kinetic model, respectively. The rate-limiting step during the EX- adsorption onto AC was determined to be pore diffusion. The thermodynamic studies revealed that the adsorption process is spontaneous and endothermic.