Green Synthesis of Nanoparticles from Plant Extracts for the Removal of Microplastics and Emerging Contaminants from Water: A Critical Review

Abstract

The unchecked release of microplastics (MPs) and emerging contaminants (ECs) pharmaceuticals, personal-care products, pesticides, endocrine disruptors, and industrial dyes into aquatic systems has outpaced the capability of conventional treatment plants, which typically remove only a fraction of these pollutants and generate secondary chemical waste in the process. Green (biogenic) synthesis of metal and metal-oxide nanoparticles (NPs) using plant extracts has emerged as a lowcost, low-toxicity alternative to chemical and physical nanofabrication routes, exploiting phytochemicals such as polyphenols, flavonoids, terpenoids, and proteins as natural reducing and capping agents. This review consolidates evidence on phyto-synthesized silver, zinc oxide, titanium dioxide, copper oxide, and iron/iron-oxide nanoparticles and nanocomposites, and examines their performance in degrading or adsorbing dyes, antibiotics, pesticides, and heavy metals pollutant classes that are mechanistically and analytically representative of the emergingcontaminant burden that also includes microplastics. Reported removal efficiencies for these green nanomaterials frequently exceed 80–99% under optimized photocatalytic or adsorptive conditions, governed by hydroxyl-radical generation, surface complexation, electrostatic attraction, and, for magnetic iron-based NPs, facile field-assisted recovery. The review further surveys the nascent but rapidly growing literature applying nanomaterials specifically to microplastic capture and degradation, highlighting magnetic and adsorptive nanoplatforms while noting that dedicated green-synthesis studies on MPs remain comparatively scarce relative to the wider emergingcontaminant literature. Key challenges synthesis reproducibility, particle agglomeration, nanoparticle recovery and secondary contamination, and the absence of standardized life-cycle and ecotoxicological assessment are discussed alongside future research priorities, including scale-up, agro-waste valorization, and hybrid photocatalytic-adsorptive nanocomposites tailored to coexisting microplastic and emerging-contaminant mixtures