Synthesis, characterization and application of xanthated Diospyros kaki (persimmon) leaves for the treatment of chemical and biological contaminants in aqueous solutions

Abstract

In this research, a one-step xanthation process was used to synthesize biosorbents from persimmon leaves (Diospyros kaki). The resulting biosorbents, referred to as MPM, exhibited high sorption capacities for Hexavalent chromium and Cd(II) at different pH values. Specifically, at pH 3, the Langmuir maximum adsorption capacity for Cr(VI)-MPM was determined to be 710 mg/g, while at pH 7, it was 622 mg/g for Cd(II)-MPM systems. The adsorption kinetics of both the metal ions followed the pseudo-2nd-order model, with R² values close to 1 (0.99). Through FT-IR and XPS studies, it was determined that ion exchange, surface complexation, and chelation were the primary mechanisms responsible for removing the analytes from water using MPM as sorbent. The presence of the -CS₂-Na group in MPM played a crucial role in these removal mechanisms. Additionally, MPM displayed notable antibacterial efficacy against S. aureus and E. coli. Considering its rapid kinetics, wide pH range applicability, impressive sorption capacity, recyclability, and effective antibacterial properties, MPM proves to be a highly suitable adsorbent for removing Hexavalent chromium and Cd(II) from industrial wastewater.