Adsorptive Removal of Toxic Heavy Metals from Wastewater Using Water Hyacinth and its Biochar: A Review

Heavy metal contamination in aquatic ecosystems is getting worse as a result of rapid industrial expansion. Biochar, recognized as an efficient and economical adsorbent, has attracted a lot of interest in environmental science particularly in heavy metals (HMs) removal. The choice of feedstock materials is one of the key parameters influencing the sorption capacity of biochars. This article reviews the utilization of low-cost biochar derived from water hyacinth (WH) for the removal of HMs. The paper covers basic details on biochar, its preparation, potential modifications, especially chemical and inorganic modifications, and investigates possible adsorption mechanisms. The applications of WH biomass and its biochar to remove HMs from aqueous solutions and industrial effluents is discussed. Research findings suggest that while WH biochar is effective in removing HMs, modifications to the carbon-rich hybrid can enhance surface properties such as surface area, pore size, functional groups etc. also magnetic properties in few cases, making them more efficient in HMs removal. However, further studies on the diverse effects of modified biochar's functional groups on HMs adsorption are necessary for future research.