Nanoclays in water treatment: Core concepts, modifications, and application insights

Abstract

Water treatment faces significant challenges due to the presence of diverse and persistent pollutants, necessitating the development of effective and eco-friendly materials. Therefore, nanoclays (NCs) have emerged as promising nanomaterials for water treatment applications. The efficacy of various NCs as adsorbents is attributed to their remarkable properties, such as high specific surface areas (up to 950 m2/g) and significant cation exchange capacities (up to 150 meq/100 g). This review encompasses the synthesis methods, modification techniques, and characterization approaches utilized in the development of NCs adsorbents, with an emphasis on understanding the structural complexity of NCs and their composites. NCs with exfoliated nanosheets demonstrate markedly improved efficacy due to the full exposure of their reactive sites. The NCs role in the simultaneous adsorption of various pollutants is highlighted, showcasing their capacity to effectively remove multiple contaminants from water in a single treatment process. Furthermore, the adsorption mechanisms and efficiency of NCs in removing varied contaminants are explored. Literature findings indicate that 2:1 clay exhibits superior removal capabilities compared to 1:1 clay for a majority of aquatic pollutants. Various techniques, including chemical treatment, thermal, and biological degradation, have been reviewed for the regeneration of spent NCs, demonstrating differing regeneration performance depending on the technique employed. The review also delves into the potential challenges and future outlook of utilizing NCs in water treatment, offering suggestions for further research, thereby emphasizing the crucial role of NCs in addressing water pollution and their promise in developing sustainable water remediation systems.