Investigation on hexavalent chromium removal from simulated wastewater using royal poinciana pods-derived bioadsorbent

The biosorption capability of royal poinciana pod-derived biosorbent was investigated for the removal of hexavalent chromium from synthetic wastewater. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were used to examine the morphology and other properties of the biochar prepared by pyrolysis at 350 °C. Operational parameters such as pH, biochar dose, interaction time, and starting metal ion concentration were tuned. A maximum metal removal efficiency of 93% was achieved at pH 6.0. Optimization investigations for experiments have also been conducted using response surface methodology which included three parameters by applying Box-Behnken design with 10.48 of model F-value and 0.93 of R2 value (coefficient of determination). The kinetic theories and isotherm models of Cr (VI) ion adsorption have also been established. Pseudo-second-order model foretells the kinetics with 0.97 R2 value. The Temkin isotherm and Dubinin-Radushkevitch provided the best-fit isotherms to explain adsorption phenomenon. This study suggests that royal poinciana pod-derived biochar may be used as an efficient, low-cost, and eco-friendly wastewater treatment bioadsorbent.