Micro-encapsulation of rare earth metal ion-doped magnesia-based alginate/pectin hybrid polymeric composites for defluoridation of water

Abstract

Fluorosis is a health problem that affects many people worldwide. To solve this problem, we developed a hybrid composite using magnesia dispersed in hybrid biopolymers (pectin and alginate), which was doped with lanthanum (La) or cerium (Ce) to yield pectin-alginate-magnesia-lanthanum (PAML) and pectin-alginate-magnesia-cerium (PAMC) hybrid composites, respectively, for efficient fluoride removal. The fabricated PAML and PAMC composites were characterized by SEM, FTIR, and EDAX studies. The manipulating factors such as dosage, pH, reaction time, initial ion concentration, temperature, and co-ions were examined under batch method. In this exploration, fluoride adsorption onto the PAML and PAMC composites was studied to illuminate the defluoridation mechanism. The PAML and PAMC composites revealed that fast kinetics was reached within 30 min. Fluoride adsorption on the PAML and PAMC composites was in accordance with the Langmuir isotherm model, with an enhanced defluoridation capacities (DCs) of 4961 and 4957 mgF⁻ kg⁻¹ respectively within 30 min at pH 6.0, respectively. Based on the characterization data and experimental results, it was determined that complexation and electrostatic interaction contributed to the fluoride capture route. Moreover, the developed PAML and PAMC composites are reusable and suitable for real water sample analysis.