Synthesis, characterization of chitosan-trithiocyanuric and its removal mechanism of Cr(VI) and Pb(II) from wastewater

A new chitosan-trithiocyanuric composite (CS@TMT) was synthesized by graft copolymerization using chloroacetyl chloride as the cross-linking agent. Using response surface analysis, the optimal conditions for the synthesis of CS@TMT were determined as: chloroacetyl chloride concentration of 2.0 mol/L, trithiocyanuric acid (TMT) addition of 7.0 g, and reaction temperature of 70 °C. The successful preparation of CS@TMT was confirmed FTIR spectrum, 13C NMR spectrum, SEM mapping, EDS, XRD and XPS. At ambient temperature (25 °C, pH=6.0, Catalyst dosage=1.0 g/L), the maximum Cr(VI) and Pb(II) adsorption amount of CS@TMT were 194.76 and 101.39 mg/g, respectively, compared to CS (97.15 and 69.76 mg/g). The Cr(VI) and Pb(II) removal process of CS@TMT was better fitted by the pseudo-second-order kinetic model and Langmuir model, and the adsorption process was spontaneous, endothermic and disordered. Under the reduction mechanism, 69.32% of Cr(VI) was reduced to Cr(III) by -SH and –OH group on CS@TMT.