Abstract
Worldwide freshwater demand will soon exceed supply if measures are not taken to mitigate inadequate wastewater treatment and its indiscriminate release into the environment. The textile industry is one of the largest consumers of freshwater and the third largest contributor to clean water pollution. Conventional treatment of textile effluent is inadequate and expensive. Adsorbent materials obtained from discarded solid waste precursors that contain high amounts of valuable metals can be an inexpensive way to obtain a highly efficient and low-cost wastewater treatment process. This study developed and explored a highly efficient adsorbent layered double hydroxide of Nickel and Indium (Ni/In-LDH) for the adsorption of widely used textile cationic dye, crystal violet (CV). The adsorbent material was synthesized by co-precipitation process of indium nitrate and nickel nitrate. The adsorbent material morphology and its adsorption capacity were investigated in different studies, such as the influence of pH, dosage, kinetics, isotherms, thermodynamics, ionic strength, adsorbent regeneration capacity, and interaction mechanisms of adsorption. Optimal operating conditions for Ni/In-LDH adsorption revealed maximum adsorption capacity Qmax of 570.94 mg g−1 at starting pH 8 and 60°C, which maintained approximately 75 % of the initial adsorption capacity in three successive adsorption/regeneration cycles. The experimental data fitted Pseudo first order kinetic model (PFO) and the Liu isothermal adsorption model. Thermodynamic studies indicated a spontaneous endothermic adsorption process, and a mechanism of physisorption of CV onto Ni/In-LDH substrate. After FTIR analysis of CV loaded Ni-In/LDH, electrostatic, hydrogen bonding, and n-π bonding interactions were suggested as the interaction mechanisms of adsorption. The Ni/In-LDH demonstrated excellent performance in the removal of CV dye in aqueous solutions compared to other high performing adsorbents.