Industrial waste biochar for heavy metal and dye remediation in wastewater: an overview

ABSTRACT The amount of waste produced by various industrial processes has increased over time as a result of the growing global population and the resulting increase in industrial production. These waste materials, which include sludge from wastewater treatment facilities and lignin-rich materials from the pulp and paper industry, contain organic compounds that can be thermochemically converted into biochar (BC), a stable carbonaceous material. This conversion not only helps reduce environmental pollution but also facilitates resource recovery. Because of its distinct qualities, the resulting BC can be used as an adsorbent to reduce contaminants in a variety of environmental media. This paper offers a concise overview of the application of BC derived from industrial waste for the treatment of heavy metals and dye-contaminated wastewater. Results indicated that the BCs were predominantly generated by pyrolysis at temperatures between 200 and 900 °C and exhibited relatively high adsorption capabilities for both heavy metal ions and dyes. The properties of the BCs, including their surface area, high porosity, morphology, and the presence of multiple functional groups, were thoroughly explored. The adsorption mechanism, the kinetics of adsorption and desorption, and the regeneration of the BC adsorbents are also covered in the work.