The Removal of Arsenic from Contaminated Water: A Critical Review of Adsorbent Materials from Agricultural Wastes to Advanced Metal–Organic Frameworks

Abstract

Arsenic pollution in potable water is a significant worldwide health concern. This study systematically evaluates current progress in adsorption technology, the most promising restorative approach, to provide a definitive framework for future research and use. The methodology entailed a rigorous evaluation of 91 peer-reviewed studies (2012–2025), classifying adsorbents into three generations: (1) Natural adsorbents (e.g., agricultural/industrial wastes), characterized by cost-effectiveness but limited capacities (0.1–5 mg/g); (2) Engineered materials (e.g., metal oxides, activated alumina), which provide dependable performance (84–97% removal); and (3) Advanced hybrids (e.g., MOFs, polymer composites), demonstrating remarkable capacities (60–300 mg/g). The primary mechanisms of removal are confirmed to be surface complexation, electrostatic interactions, and redox precipitation. Nevertheless, the critical analysis indicates that despite significant laboratory efficacy, substantial obstacles to field implementation persist, including scalability limitations (approximately 15% of materials are evaluated beyond laboratory scale), stability concerns (e.g., structural collapse of MOFs at extreme pH levels), and elevated costs (e.g., MOFs priced at approximately $230/kg compared to $5/kg for alumina). The research indicates that the discipline must transition from only materials innovation to application science. Primary objectives include the development of economical hybrids (about $50/kg), the establishment of uniform WHO testing standards, and the implementation of AI-optimized systems. The primary objective is to attain sustainable solutions costing less than $0.10 per cubic meter that satisfy worldwide deployment standards via multidisciplinary cooperation.