A critical review of clay-based composites with enhanced adsorption performance for metal and organic pollutants

• Published in: Journal of hazardous materials Vol. 369; pp. 780 - 796
• Main Authors: Han, Huawen, Rafiq, Muhammad Khalid, Zhou, Tuoyu, Xu, Rong, Mašek, Ondřej, Li, Xiangkai
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05-05-2019
• Subjects: Biochar; Clay-based composites; Metal; Organic pollutants; Wastewater remediation; Organic pollutants; Metal; Biochar; Wastewater remediation; Clay-based composites
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2019.02.003

•Multi-modified clay composites show better performance than single-modified clays.•Clay composites with various modifications exhibit different absorption mechanisms.•Clay-biochar composites represent an environmentally superior alternative.
[Display omitted]
Adsorption techniques offer unique advantages owing to the use of synthetic (e.g., nanosized metal oxides and polymer-functionalized nanocomposites) and natural (e.g., clay and biochar) materials for pollutant removal. Although the most widely used adsorbent is activated carbon, extensive studies have highlighted the promising potential of modified clay minerals and biochar for removing heavy metal and organic pollutants from industrial, drinking, and eutrophic wastewater, due to their low cost and easy accessibility. However, clay modification using acids, calcination, polymers, or surfactants exhibits relatively low absorption/regeneration ability towards antibiotics, aromatics, and various dyes. The coexistence of numerous contaminants in industrial wastewater inhibited the performance of adsorbents, which accelerated the development of novel modified clay composites such as clay-biochar, organo-bentonite/sodium alginate beads, and enhanced biochar. This review summarizes recent studies and absorption mechanisms concerning clay composites based on various modification methods and component materials. The comparison of clay composites used for the removal of organic and inorganic contaminants provides valuable insight into real wastewater treatment. Knowledge gaps, uncertainties, and future challenges involved in the fabrication and regeneration of modified clay composites are also identified.