Sustainable separation technologies for heavy metal removal from wastewater: An upgraded review of physicochemical methods and its advancements

This study comprehensively evaluates both physical and chemical methods for removing heavy metals from wastewater, assessing their efficiency, cost-effectiveness, and sustainability. Traditional techniques such as adsorption, coagulation-flocculation, chemical precipitation, membrane filtration, ion exchange, and electrochemical methods are widely used due to their rapid action and reliability. However, challenges such as high operational costs, secondary waste generation, and limited selectivity necessitate the exploration of more sustainable alternatives. A key novelty of this review lies in its in-depth analysis of emerging remediation technologies, including advanced electrochemical treatments, bioadsorbents, and hybrid approaches. The study highlights recent breakthroughs in nanomaterial-based adsorbents, which offer high adsorption capacities (e.g., graphene oxide with >90% removal efficiency for Pb(II) and Cd(II)) and improved regeneration potential. Based on the comprehensive literature study, this review emphasizes the need to shift from synthetic wastewater studies to real-world industrial effluents, ensuring practical applicability. Future research should prioritize eco-friendly, cost-efficient materials with high selectivity and recyclability, such as biopolymer-based flocculants and functionalized membranes. This review provides valuable insights for optimizing heavy metal removal strategies, aligning with global environmental goals and sustainable water treatment advancements. ▪ Examines key sources of heavy metal contamination and their effects on ecosystems. ▪ Provides an overview of traditional physical and chemical treatment methods. ▪ Analyzes adsorption mechanisms of bio-adsorbents for effective pollutant removal. ▪ Discusses advancements in electrochemical techniques for enhanced metal extraction. ▪ Emphasizes the importance of sustainable and cost-efficient remediation strategies.