Tannic acid as a green chemical for the removal of various heavy metals: A critical review of recent developments

Heavy metals are persistent, bioaccumulative, and toxic pollutants that greatly challenge the environment. Pursuing green and efficient methods to remove these contaminants from wastewater has become a key focus in environmental research. Tannic acid (TA), a natural plant-derived secondary metabolite, has demonstrated exceptional potential for heavy metal removal. This review provides a comprehensive analysis of TA-based materials, focusing on their performance, influencing factors, underlying mechanisms, thermodynamic models, and regeneration in the removal process. Enhancing the adsorption capacity of TA-based materials for targeted heavy metals remains a priority, requiring further modifications and optimizations. Expanding the operational range of pH and temperature and minimizing interference from coexisting substances are also crucial for practical applications. Additionally, kinetic and adsorption models offer valuable insights into removal mechanisms while providing predictions and guidance for real-world implementations. By offering an in-depth overview, this review serves as a critical resource for advancing the development of sustainable and effective TAbased adsorbents for wastewater treatment.