Removal of heavy metals from industrial effluents by using biochar

Abstract Heavy metal is a term commonly envisaged to be those metals whose density surpasses 5 g per cubic centimeter. An enormous number of elements fall into this group, but Cd, Cr, Cu, Ni, As, Pb, Hg, and Zn are those of relevance in an environmental context. Heavy metals cause serious health issues such as organ injury, nervous system impairment, reduced growth and development, cancer, and, in extreme cases, death. The release of large amounts of metals through industrial wastewater has become hazardous to living organisms as they easily absorb and accumulate heavy metals into their body due to its high solubility in an aquatic environment. Therefore, it is essential to treat metal-contaminated wastewater before its discharge to the environment. There are various types of treatment processes such as membrane partitioning, electrodialysis, chemical precipitation, ion exchange, electrochemical removal, photocatalytic process, and adsorption. Adsorption is acknowledged as a financially cheap practice for heavy metal expulsion from wastewater as it is economical, simple to deal with, and exceedingly productive. This chapter explain the adsorption technique by using biochar. Biochar is the carbon-rich residue left behind when biomass, for example, wood, fertilizer, or leaves, is heated in a shut vessel with next to zero accessible oxygen. In more methodical terms, biochar is obtained by thermal disintegration of organic material under partial or no source of oxygen (O2) and at comparatively low temperatures (