Chitosan–Clay Composites for Wastewater Treatment: A State-of-the-Art Review

In recent decades, increased domestic and industrial activities have led to the release of various pollutants into the aquatic environment. A robust and eco-friendly technique for removing these pollutants from wastewater is a crucial need. Among existing technologies, adsorption is considered to be a simple, cost-effective, and sustainable method. Recently, chitosan–clay nanocomposites have emerged because of their high abundance, ease of fabrication, and efficacy as adsorbents. Quantitatively, this particular class of composites is capable of removing ∼99% of dyes, metals, and harmful negative ions from various solutions. Also, the composite is designed to remove a maximum of ∼94% of the targeted herbicides from media under investigation. This review summarizes important information about this adsorbent in removing micropollutants from various water sources. A short overview of the chemical structure and the modification of chitosan and clay, along with their interaction within the composite matrix and with contaminants, is presented. Finally, a critical analysis of the removal performance of these composites compared with that of other industrial adsorbents is provided. Future research directions are suggested on the basis of the technological challenges faced in the industrial implementation of these materials.