Green Synthesis of Metal Oxide Nanoparticles Using Plant Extracts for Removal of Berberine Hydrochloride from Wastewater: A Comprehensive Review

Water pollution caused by pharmaceutical residues, particularly berberine hydrochloride (BRB), has emerged as a significant environmental challenge in recent decades. Conventional wastewater treatment plants are not specifically designed to remove complex organic micropollutants, such as pharmaceuticals, so these compounds persist in aquatic ecosystems and can cause ecotoxicological effects. Advanced oxidation processes and photocatalytic degradation using metal oxide nanoparticles (NPs) have shown remarkable promise for addressing this pollution. Among these, titanium dioxide (TiO₂) NPs synthesized via green chemistry approaches using plant extracts represent a sustainable, environmentally friendly solution. This comprehensive review examines the properties, synthesis methods, and photocatalytic mechanisms of TiO₂ NPs for BRB degradation. We discuss the factors influencing catalytic efficiency, including surface area, crystalline structure, particle size, and operating conditions such as pH, temperature, and light irradiation. Furthermore, this review highlights the potential of plant-mediated synthesis using local flora such as Scirpoides holoschoenus , a sedge native to Saudi Arabia, as an innovative and sustainable approach to nanomaterial fabrication. The integration of green chemistry principles with nanotechnology offers promising opportunities to develop cost-effective, non-toxic, and environmentally sustainable solutions for removing pharmaceutical pollutants in wastewater treatment systems.