Hybrid adsorbents for pollutants removal: A comprehensive review of chitosan, glycidyl methacrylate and their composites

Adsorption is widely recognized as a superior pollutant removal technique due to its minimal chemical requirements, reducing toxicity, and simplifying handling compared to other methods. A variety of adsorbents, including natural polymers like chitosan and synthetic polymers such as glycidyl methacrylate (GMA), have demonstrated effective pollutant remediation capabilities. While these materials were initially employed in their natural forms, recent advancements have shifted toward the development of composite materials to enhance performance. This review provides a comprehensive examination of chitosan (CS), GMA, and their hybrids and nanocomposites as adsorbents, focusing on their availability, stability, sorption capacity, and durability. Characterization techniques for evaluating surface modifications and their impact on adsorption mechanisms are discussed in detail. Furthermore, the review explores various modifications of CS and GMA with functional materials, emphasizing their adsorption mechanisms and effectiveness in removing metal ions and dyes. Key factors affecting adsorption efficiency, such as pH, temperature, adsorbent dosage, and contaminant concentration, are critically analyzed. The key kinetic, equilibrium, and thermodynamic studies essential for understanding adsorption efficiency were assessed. A comparative analysis of different adsorbents and their variants is presented, along with insights into specific functionalization techniques aimed at enhancing adsorption capacities. This review aims to guide readers in selecting adsorbents that provide the highest return on investment. Additionally, it addresses the challenges and future directions of adsorption technology, emphasizing the need for continued research, particularly in scaling up applications with real-world water samples and advancing polymer performance through innovative modifications.