Microplastic removal by coagulation/flocculation: A review and bibliometric analysis

• Coagulation/flocculation is effective for microplastic removal in water • Bibliometric analysis reveals exponential growth in MPs removal studies • Aluminum and iron salts dominate coagulation-based MPs removal research • Microplastic properties strongly influence coagulation efficiency • Biocoagulants show promise with lower environmental footprint • Integrated treatment trains enhance microplastic removal performance Microplastics (MPs) are increasingly detected in aquatic environments and engineered water systems, raising concerns about persistence and potential human exposure. Although coagulation/flocculation is a scalable and widely implemented unit process in conventional drinking-water and wastewater treatment, evidence for MPs removal remains fragmented across matrices, MPs properties, and coagulant systems, limiting comparability of studies and practical translation; furthermore, few studies integrate evidence synthesis with formal bibliometric mapping. This study systematizes the literature on coagulation/flocculation for MPs removal from aqueous media and analyzes key bibliometric indicators. Searches in Scopus and Web of Science were conducted using a PICO-based strategy and PRISMA-guided screening. Bibliometric analysis (Bibliometrix) covered 219 documents, and 29 original experimental studies were examined in depth to address the PICO questions. Results indicate rapid publication growth, with China, India, Canada, and the United States as leading contributors. Most experiments use synthetic effluents, enabling mechanistic interpretation; however, high removals have also been reported for real matrices (river water, wastewater, and drinking water). Removal performance depends on MPs physicochemical characteristics, coagulant type and dose, and matrix effects, including natural organic matter and co-contaminants. Aluminum- and iron-based salts are most frequently investigated, while biocoagulants and bioflocculants show promising performance with potentially lower environmental footprints. Overall, coagulation/flocculation is a key component of future treatment trains for mitigating MP pollution; nevertheless, critical gaps remain for MPs <10 μm, methodological standardization, cost-effectiveness, and sludge/residual management to enable robust scale-up.