Harnessing potential of smart and conventional spent adsorbents: Global practices and sustainable approaches through regeneration and tailored recycling

Efforts aimed at the sustainable management of spent adsorbents (SPAs) obtained after wastewater treatment have gained significant attention, aligning with the principles of the circular economy. This comprehensive review evaluates the effectiveness of both conventional adsorbents and smart adsorbents (SAs) in addressing organic and inorganic contaminants present in wastewater. It encompasses a wide array of recovery and regeneration techniques for spent SAs, including magnetic separation, pH and gas responsiveness, thermal and light activation, chemical desorption-facilitated regeneration, and sequential recycling of conventional SPAs, highlighting their transformation into valuable commodities such as antimicrobial agents, catalysts, fertilizers, construction materials, and secondary adsorbents. Integrating eco-friendly regeneration methods for SAs and sequentially recycling conventional SPAs into high-value products provides a sustainable solution that effectively mitigates secondary pollution proliferation. This synergistic approach regenerates SPAs and elevates them into valuable resources, thereby adopting environmental stewardship and resource efficiency. Optimizing SAs demands targeted research on their design and functionalization for greater specificity, faster response times, and improved reusability. Establishing clear life cycle assessment metrics, encompassing energy consumption, greenhouse gas emissions, resource use, and environmental impacts, are essential for evaluating SPA regeneration and recycling. In summary, both regeneration and sequential recycling strategies substantially benefit sustainable waste management. The choice hinges on the properties of smart and conventional SPAs, contaminants, resources, and environmental factors. We also explore integrating regeneration and reuse with renewable energy to expedite sustainable development goals.