Recent Advances and Challenges in Chromium Removal From Aqueous Solutions Using Adsorbent Materials

ABSTRACT The review represents recent progress and challenges related to the removal of chromium from aqueous solutions by different adsorbent materials. The principal classes of adsorbents were biochar, activated carbon, polymeric materials, graphene oxide (GO), metal‐based composites, and bio‐adsorbents applied for Cr(VI) and Cr(III) removal performance. Biochar and bio‐adsorbents became economically viable and environmentally friendly alternatives, especially if their origin came from agricultural or industrial waste. Advanced materials like GO and polymer composites showed outstanding adsorption capacities; however, they had bottlenecks regarding cost and scalability. Metal‐based composites—nano‐zero‐valent iron and magnetite‐coated ones in particular—offered both reduction and adsorption capabilities, though some of them indeed suffered from challenges in practical application because of possible leaching of nanoparticles. Another important finding of this review is the nonuniform performance of adsorbents within real wastewater systems, which generally involve competition among contaminants and dynamic environmental conditions. Other major barriers involve economic feasibility of advanced materials, trade‐offs in efficiencies of various regeneration approaches, and lack of scalability of novel adsorbents. Emerging trends in the hybrid development of materials and in the incorporation of adsorbents with other advanced technologies, such as membranes and bioreactors, highlight efforts to overcome such limitations. Future studies should focus on developing green and low‐cost adsorbents, improving regeneration methods in an eco‐friendly manner, and conducting large‐scale field verification to confirm the process's performance in realistic conditions. Out of these knowledge gaps, a smooth route will emerge toward effective and sustainable solutions for chromium‐polluted water with grave implications in environmental protection and public health.