Advantages of the reuse of spent adsorbents and potential applications in environmental remediation: A review

• Innovative Applications of Spent Adsorbents. • Environmental and Economic Benefits. • Mechanistic Insights into Adsorbent Reuse. Adsorption represents a highly promising methodology for wastewater treatment, characterized by its operational simplicity and economic efficiency in extracting environmental pollutants. This study investigates the possible uses and benefits of recycling wasted adsorbents containing metals in various environmental remedy projects to tackle the urgent issue of secondary contamination. Recycling used adsorbents are proposed to reduce secondary pollution and provide numerous economic and ecological advantages in wastewater treatment. This study comprehensively analyzed the existing literature, carefully evaluating the effectiveness of different used adsorbents in eliminating contaminants and their capacity for regeneration and later reuse. Furthermore, the novelty of the review lies in its exploration of recycling spent adsorbents particularly those containing heavy metals (HMs), as a sustainable solution for wastewater treatment. Results indicate that spent adsorbents, particularly those treated with ionic liquids, achieve extraction efficiencies above 80 % for heavy metals and show enhanced stability during several regeneration cycles. Utilizing recycled wasted adsorbents is a viable method for sustainable wastewater treatment, with significant potential to reduce environmental pollution and support a circular economy.