Eco-friendly synthesis of metal oxide nanoparticles (ZnO, MgO and CuO) for efficient water purification: A review

Escalating water pollution and scarcity necessitate the development of advanced, sustainable water treatment technologies. This review presents a critical and comprehensive analysis of the green synthesis of ZnO, MgO, and CuO nanoparticles (NPs), as well as their integration into membrane technologies for effective water remediation. Green synthesis harnesses biological resources such as plant extracts, offering a low-cost, energy-efficient, and environmentally friendly alternative to conventional methods while producing nanoparticles with superior catalytic and antimicrobial properties. We elucidate how the physicochemical characteristics of these green-synthesized nanoparticles enhance membrane hydrophilicity, antifouling behavior, and photocatalytic degradation of contaminants, thereby improving water purification efficiency. Additionally, this review addresses current challenges in controlling particle size, morphology, and scalability, emphasizing the need for advanced synthesis strategies such as microwave-assisted, supercritical CO₂, and hybrid green synthesis methods to optimize nanoparticle production for industrial applications. By bridging the gap between sustainable nanoparticle synthesis and practical membrane modification, this review emphasizes the potential of green nanotechnology to transform water treatment processes, aligning with sustainability.