Carbon Dots for Wastewater Treatment: Mechanisms, Challenges and Future Perspectives

Abstract

The growing global water crisis emphasizes the dire need for sustainable and eco-friendly technological innovations to ensure clean water availability not only for the current generations but also for future generations. Carbon dots (CDs), a class of carbon based nanomaterials (CBNs) offers a sustainable solution for wastewater treatment because of their distinctive physicochemical and biological properties. This review critically evaluates the production methods of CDs, ranging from top-down to bottom-up production methods and systematically analyzes their properties. CDs present distinct benefits such as low inherent toxicity, high water dispersibility, photoluminescence tunability and environmental acceptability, making them viable candidates for pollutant detection and removal via adsorption, catalysis, filtration and biological treatments. A bibliometric analysis highlights expanding academic research interest; however, practical, real-world limitations continue to hinder industrial-scale deployment. Despite their laboratory-scale performance, several unresolved issues are to be addressed before commercial translation can occur. These bottlenecks include poor batch-to-batch reproducibility, inconsistent quantum yields, high purification complexities, long-term operational instability and a lack of validation under real wastewater conditions. Furthermore, the majority of current literature is confined to synthetic, single-pollutant aqueous systems, neglecting the matrix complexities of real industrial effluents. This review critically analyzes these deficiencies and identifies key research gaps concerning protocol standardization, environmental toxicity, cost-effective recovery and techno-economic feasibility. Future development pathways, including scalable green synthesis and automated optimization, are proposed to bridge the gap between laboratory discovery and large-scale engineering applications.