Adsorptive Elimination of Rhodamine B Dye by Synthetic Clay-Based Hetero-metallic Oxide Nanocomposite KAB-Ben for Rapid Wastewater Treatment

A bentonite clay-based hetero-metallic oxide composite, i.e., KAB-Ben, was synthesized by impregnation of bentonite clay with potassium salt of Al-substituted Keggin tungstoborate (KAB) via a simple co-precipitation method. The composite was morphologically characterized by FTIR, SEM-EDX, XRD, and TGA, and its efficiency for removal of rhodamine B (RhB) from wastewater was investigated to compare with unmodified bentonite. The adsorptive potential was explored by changing the experimental parameters such as contact time, adsorbent dose, pH, temperature, agitation speed, and the reusability. KAB-Ben composite was able to remove 92.2% of RhB within the first 20 min which was much higher than bentonite. The q max values of bentonite and KAB-Ben were 14.2 and 208.3 mg/g, respectively. Kinetic study revealed that the adsorption mechanism followed pseudo-second-order kinetics. Furthermore, the adsorbent was able to be reused thrice without any drastic loss of adsorption activity. The composite possessed satisfactory tolerance over various ranges of pH, temperature, and dye concentration. The current research is an insight into a new cost-effective and environmentally benign adsorbent for detoxification of RhB from aqueous solution. Graphical Abstract