Application of bone chars for the removal of chemical contaminants from water resources: a review

This present study reports the comprehensive review on the application of bone chars for the removal of heavy metals, fluorides, dyes and pharmaceuticals from water resources. The study focused on reviewing the peer-reviewed published papers on bone chars that were obtained from selected scientific databases. At optimum conditions, the highest adsorption capacities of copper, fluoride, and arsenic ions, dye and pharmaceuticals attained are 9615, 28.6, 9.82, 58.35 and 166 mg/g, respectively. The removal efficiencies were 100, 99, 99.18, 99 and 98%, respectively. The results show that the equilibrium adsorption data mainly conformed to Langmuir and Freundlich isotherm models. The kinetic data were supported by pseudo-second order model. Surface complexation, ion exchange, precipitation and electrostatic interactions are the main mechanisms involved in the sequestration of chemical contaminants by bone chars. Studies on optimization of both synthesis conditions and adsorption process variables, including fixed-bed experiments are needed. The use of DFT to gain detailed insights on adsorption mechanisms should be explored. Techno-economic studies and life-cycle assessment studies are also required to inform policy and sustainability.