Utilization of rice husks functionalized with xanthates as cost-effective biosorbents for optimal Cd(II) removal from aqueous solution via response surface methodology.

Pristine rice husk (RH), a kind of agricultural waste based biosorbent, was chemically modified by introducing sulfur-bearing groups with the CS2 treatment under caustic medium. Using response surface methodology (RSM), the interactive effects of three preparation variables on the cadmium uptake and material yield of xanthate-modified rick husk (RH-X) were investigated, and two quadratic regression models were developed to correlate the preparation parameters to the two responses. Through process optimization, the optimal RH-X was finally obtained under the optimum synthesis conditions (i.e., 1.00 CS2-RH ratio, 60.00min xanthation contact time and 18.50°C xanthation temperature), resulting in 138.85mgg-1 of cadmium uptake, and 68.63% of RH-X yield, strictly similar to the values predicted from the models, with extremely small errors of 0.85 and 0.96%, respectively. Overall, cheap and abundant raw materials, low-cost and easily-controlled preparation and excellent cadmium adsorption ability can make RH-X a preferred biosorbent for wastewater decontamination.