Advances in Membrane Technologies for Heavy Metal Removal from Polluted Water: A Comprehensive Review

Abstract

Heavy metals and other hazardous substances contaminating water have harmful effects on plants, animals, and potentially human health. Therefore, it is essential to explore ways to extract toxic materials from polluted water. Removing mineral contaminants from water is crucial for promoting a healthy environment and protecting human health. Among the existing methods, membrane-based techniques are particularly effective in reducing pollutants, especially heavy metals, in water systems. Membrane filtration is extensively researched and known for its high efficiency, although cost factors limit its broader application. Reverse osmosis technology achieves the highest heavy metal removal efficiency, ranging from 98.0% to 99.9%. While reverse osmosis boasts high operational efficiency, it demands a significant amount of energy. To maintain the sustainability of reverse osmosis efficiency, suitable and intermediate conditions must be established. Polymeric membranes provide an energy-efficient water purification solution, although they face fouling issues during filtration. Membrane fouling, a prevalent challenge for all membrane-based water and wastewater treatment technologies, refers to the accumulation of dissolved or suspended solids on or within the membrane pores, which deteriorates membrane performance. Surface modification of membranes is one strategy to alleviate fouling and sustain high water productivity levels. Two main methods have been extensively explored: grafting polymer chains onto the membrane surface and applying a thin film to the membrane surface. The objectives of these membrane modifications include increased fouling resistance, improved selectivity, and extended membrane lifespan. This study thoroughly analyzes results from various experiments conducted over the past two decades to identify the most relevant membrane filtration processes for different contaminant profiles.