Dithiocarbamate-modified cellulose-assisted ternary coagulation-flocculation system for selective removal of arsenite...

Dithiocarbamate (DTC) ligands exhibit strong selectivity toward metal ions, inspiring the development of a novel DTC-modified cellulose (DMC-Pro) for heavy metals (HMs) removal. However, the inherent solubility and aggregation of DMC-Pro in aqueous media have limited its practical application. In this study, a water-soluble DMC-Pro was employed as a dual-function chelating flocculant to develop a novel ternary coagulation-flocculation system (TCFS), integrating DMC-Pro with an inorganic coagulant and a synthetic polymer flocculant. Batch experiments optimized the TCFS parameters for effective As^III removal by evaluating the influence of DMC-Pro and coagulant dosages, pH, and flocculant type. The DMC-Pro-assisted TCFS achieved efficient As^III removal without interference from coexisting ions at environmentally relevant concentrations and demonstrated > 95 % removal efficiency for multiple HMs (Co^II, Ni^II, Cu^II, Zn^II, As^III, Se^IV, Ag^I, Cd^II, and Pb^II). Application to arsenic-contaminated natural dam sediment-water mixtures validated its practical effectiveness and compliance with environmental standards. Mechanistic investigations using zeta potential, FE-SEM/EDX, FT-IR, XPS, and XAFS analyses revealed a multi-step process involving As^III-DTC complexation, charge neutralization, and polymer bridging. These findings highlight DMC-Pro-assisted TCFS as a promising, versatile, and sustainable strategy for the selective removal of As^III and other HMs from complex environmental matrices.