Natural Mineral and Biopolymers Based Adsorbent for Cationic Dyes Removal: Glutaraldehyde Crosslinked Alginate/Kaolin Bead

Abstract

In this study, the removal of methylene blue (MB), malachite green (MG) and methyl violet (MV) from aqueous media by adsorption process using glutaraldehyde crosslinked alginate/kaolin hydrogel bead (g-Alg/Kao) was investigated. First of all, g-Alg/Kao was synthesized. g-Alg/Kao beads were investigated by FTIR analysis. Adsorption parameters such as solution pH value, adsorbent dosage, agitation time and initial dye concentration, which affect the removal of cationic dyes (MB, MG, MV) from aqueous solutions, were studied with this newly synthesized environmentally friendly composite adsorbent. Obtained experimental data were applied to Langmiur, Freundlich, Dubinin Radushkevich, Scatchard and Temkin isotherm models and related parameters were derived. The results revealed that the experimental data fit the Langmiur model better. According to Langmiur isotherm, the maximum adsorption capacity of MB, MG, MV was found to be 294.1, 122.0 and 357.1 mg/g, respectively. A batch contactor requires about 60 min contact time to achieve 84 % (for MB), 62% (for MG), 81% (for MV) removal percentages from aqueous solution. g-Alg/Kao show exceptional dye adsorption capability and high adsorption efficiency for MB, MG and MV removal from water. It was observed that the adsorption kinetics fit the pseudo-second-order model. Thermodynamic evaluation of adsorption showed that adsorption is endothermic, and adsorption is spontaneous. Recovery studies have shown that gAlg/Kao composite has good adsorption/desorption performance.