Progress in Preparation and Application of Modified Biochar for Improving Heavy Metal Ion Removal From Wastewater

Modified biochar (BC) is reviewed in its preparation, functionality, application in wastewater treatment and regeneration. The nature of precursor materials, preparatory conditions and modification methods are key factors influencing BC properties. Steam activation is unsuitable for improving BC surface functionality compared with chemical modifications. Alkali-treated BC possesses the highest surface functionality. Both alkali modified BC and nanomaterial impregnated BC composites are highly favorable for enhancing the adsorption of different contaminants from wastewater. Acidic treatment provides more oxygenated functional groups on BC surfaces. Future research should focus on industry-scale applications and competitive sorption for contaminant removal due to scarcity of data.