Dicarboxylic acid cross-linked metal ion decorated bentonite clay and chitosan for fluoride removal studies

Abstract

This study focused on the synthesis of a dicarboxylic acid (malic acid (A)), metal ion decorated bentonite clay (BC) modified with chitosan (CS) and the investigation of its defluoridation efficiency in fluoride contaminated groundwater. The synthesized adsorbent showed a fluoride removal capacity of 9.87 mg g⁻¹. Batch adsorption studies were conducted to establish the effect of various parameters such as contact time, pH, initial concentration, and competitor ions. The adsorption isotherms of Freundlich, Dubinin–Radushkevich, and Langmuir were studied and the Freundlich isotherm fitted the data well. Kinetic studies showed that the adsorption process follows pseudo second order kinetics. Thermodynamic studies revealed that the fluoride adsorption process is spontaneous and endothermic. Reuse and regeneration studies were executed for effective application of the nanocomposite. The synthesized adsorbent also has potential for real water treatment applications.