Agro-waste based adsorbents as sustainable materials for effective adsorption of Bisphenol A from the environment: A review

Endocrine disruptive compounds (EDC) pose a great threat to the normal functioning of the human endocrine system leading to various illnesses and malfunctions. Several EDCs have been reportedly found in receiving water bodies including Bisphenol A (BPA). Bisphenol A (BPA) is a synthetic organic compound that is mainly used in the production of polymer materials polycarbonate and epoxy resin. BPA has been found all over the world due to widespread use and erroneous processing techniques, raising questions about its effects on the environment and human health. Removal strategies however are ineffective as residues of EDCs escape through various treatment plants and into drinking water. Adsorption using activated carbon from agro-waste however is an economical and sustainable substitute to the utilization of expensive commercial activated carbon for the sequestering of BPA. This review aims to provide a comprehensive overview of the use of agro-wastes for the uptake of BPA and operational parameters for its biosorption. Most adsorption of BPA took place at acidic pH mostly at pH 3 and the prominent mechanism was the π- π interactions. The isotherm, kinetics and thermodynamics modelling of BPA adsorption was extensively discussed. Langmuir and Freundlich isotherm models were best fit to equilibrium data, pseudo-second-order mostly described the kinetic studies with pore diffusion mechanism dominance. Most acid-functionalized sustainable agro-waste adsorbents had better percentage removal efficiency (%RE) for BPA uptake having %RE > 90% This study also covers the reusability of agro-waste for the uptake of BPA. This study will therefore enable upcoming researchers to explore means of applying and modifying agro-waste for the removal of BPA thereby remediating the environment. A research gap has been identified for researchers to explore more utilization of nanoparticles, composite nanomaterials, polymeric materials, and other mesoporous and microporous materials in the future to remove BPA. These future studies should be conducted on a laboratory, pilot, and industrial scale. The information on the disposal of spent agro-waste adsorbents once they have lost their BPA adsorption performance should be reported.