Biochar modification to enhance sorption of inorganics from water

• Published in: Bioresource technology Vol. 246; pp. 34 - 47
• Main Authors: Sizmur, Tom, Fresno, Teresa, Akgül, Gökçen, Frost, Harrison, Moreno-Jiménez, Eduardo
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2017
• Subjects: Activation; Adsorption; biochar; biofilm; Charcoal; Inorganic; Modification; Organic Chemicals; Pollution; sorbents; Sorption; Steam; surface area; technology; Water Pollutants, Chemical; Sorption; Modification; Pollution; Activation; Inorganic
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2017.07.082

•Modifications of biochar can enhance the sorption of inorganic pollutants.•Activation with steam, acids and bases increases sorption of metal cations.•Biochar-based composites increase sorption of oxyanions, but also sorb metal cations.•Future work may align biochar design with the objectives of the circular economy. Biochar can be used as a sorbent to remove inorganic pollutants from water but the efficiency of sorption can be improved by activation or modification. This review evaluates various methods to increase the sorption efficiency of biochar including activation with steam, acids and bases and the production of biochar-based composites with metal oxides, carbonaceous materials, clays, organic compounds, and biofilms. We describe the approaches, and explain how each modification alters the sorption capacity. Physical and chemical activation enhances the surface area or functionality of biochar, whereas modification to produce biochar-based composites uses the biochar as a scaffold to embed new materials to create surfaces with novel surface properties upon which inorganic pollutants can sorb. Many of these approaches enhance the retention of a wide range of inorganic pollutants in waters, but here we provide a comparative assessment for Cd2+, Cu2+, Hg2+, Pb2+, Zn2+, NH4+, NO3−, PO43−, CrO42− and AsO43−.