Isothermal and Kinetics Modeling Approach for the Bioremediation of Potentially Toxic Trace Metal Ions Using a Novel...

The presence of trace metals in wastewater brings serious environmental pollution that threatens human health as well as the ecosystem throughout the world due to their non-biodegradability nature. The present study focuses on the bioremediation of toxic trace metals, namely arsenic (As), cadmium (Cd), and chromium (Cr), using Acalypha wilkesiana leaf raw biomass. The optimization of various process variables was done to determine the removal percentage of trace metal using Acalypha wilkesiana leaf raw biomass, and the optimum conditions were an adsorbent dose of 0.5 g, contact time 10 h, 8 h, and 10 h, process temperature 30 °C, initial concentration of trace metal as 30 µg/L, 30 mg//L, and 40 mg/L, and pH of 7.5, 7 and 7.5 for As⁵⁺, and Cd²⁺ and Cr⁶⁺, respectively. Acalypha wilkesiana leaf raw biomass is characterized using a scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transformation infrared spectroscopy (FTIR), zeta potential before and after adsorption of the trace metal ions. The study was well fitted for the equilibrium data for Langmuir isotherm for As⁵⁺, Cd²⁺, and Cr⁶⁺, Freundlich for As⁵⁺, Dubinin-Radushkevinch (D-R) for Cr⁶⁺, and Temkin for As⁵⁺ and Cr⁶⁺. The adsorption of all three trace metals was confirmed by the kinetics and thermodynamic studies to be following pseudo-second-order kinetics with endothermic as well as spontaneous processes, respectively. Thus, the present study indicates Acalypha wilkesiana leaf raw biomass as an effective and efficient novel biosorbent to remediate different trace metals from aqueous systems with its possible application in existing and novel methods for wastewater management.