Design and Synthesis of Kaolin/Alumina Incorporated Biopolymeric Hybrid Composites for Efficient Malachite Green Adsorption

The toxic dyes contaminated in water resources can cause dangerous diseases and severely affect the living organisms. In this research work, kaolin (KL) clay and alumina (AO) ceramic was incorporated with alginate (Alg) and chitosan (CS) biopolymers namely KLAOAlg and KLAOCS composites were developed and utilized for adsorption of most toxic malachite green (MG) dye. The morphology and physico-chemical nature of the developed KLAOAlg and KLAOCS composites were investigated via SEM, FTIR, elemental mapping, XRD and EDAX analysis. The batch mode experiments were performed to investigate the different factors that affecting the MG adsorption including reaction time, pH, co-ions, adsorbent dosage, initial concentration of MG and temperature. Both KLAOAlg and KLAOCS composites reached their utmost adsorption capacity of 42.00 and 45.00 mg/g at a shaking time of 40 min with a composite dosage of 0.1 g and 100 mg/L MG solution. The equilibrium data collected for the adsorption of MG was most fit with the Langmuir isotherm, whereas the kinetic data aligned with the pseudo-second-order model. The results derived from thermodynamic considerations indicate that the adsorption process was endothermic, feasible, and spontaneous. The mechanism for superior adsorption of MG onto the KLAOAlg and KLAOCS composites is primarily driven by hydrogen bonding and electrostatic interaction. The regeneration test explored that the KLAOAlg and KLAOCS composites can be reused upto five cycles and utilized as promising adsorbents for MG removal.