PARAQUAT SORPTION ON CALCIUM ALGINATE GEL BEADS

摘要

Environmental pollution and accidental poisoning by agricultural chemicals have become a major social problem. The use of calcium alginate gel beads to remove paraquat dichloride (1,1'-dimethyl-4, 4- bipyridinium dichloride) from wastewater under different batch experimental conditions was investigated. Special attention was paid to the effects of pH and the initial concentration of paraquat. We determined that the sorption of paraquat was pH-dependent and based on isotherm curves; the Langmuir model appeared to fit the sorption better than the Freundlich model. It was found that the rate of sorption of paraquat onto the calcium alginate gel beads increased with pH. In all cases, the maximum possible adsorption occurred in the first 120 min. The pseudo-second-order chemical reaction model appears to provide a good correlation, confirming that the dominant mechanism of calcium alginate gel bead sorption is chemical sorption.