A review on advances in hybrid magnetic nanoparticles for microplastics removal: Mechanistic insights and emerging prospects

Synthetic polymer particles less than 5 mm in size, called microplastics (MPs), have emerged as ubiquitous and unbiodegradable harmful aquatic and terrestrial environment pollutants with a substantial environmental risk potential to human health. They are heterogeneous, increasing their surface-area-to-volume ratios and capacities to adsorb and transport persistent organic pollutants (POPs), heavy metals, and pathogens. Since coagulation, filtration, and biological degradation are traditional remediation techniques, they tend not to remove MPs efficiently, particularly MPs that are less than 10 μm. Recently, hybrid magnetic nanoparticles (HMNPs), which are composed of magnetically active cores that are functionalized using organic, inorganic, or composite materials, have shown potential in overcoming this shortage. This review critically examines recent developments in HMNP-based systems for microplastic remediation, focusing on synthesis, surface engineering, and functionalization. It highlights key material types such as carbon-based hybrids, metal-organic framework (MOF) composites, and silica-supported magnetic nanohybrids. It discusses mechanisms including magnetic separation, physisorption, photocatalytic degradation, and Fenton/photo-Fenton processes. Scalability, environmental safety, regeneration strategies, and pilot-scale applications are also discussed.