Turning the tide on microplastic pollution: Leveraging the potential of geopolymers for mitigation

Microplastic pollution represents a significant environmental challenge due to its persistence and role as a vector for harmful contaminants. Conventional mitigation strategies, such as filtration, oxidative degradation, and microbial treatments, often exhibit limitations in efficiency, scalability, or result in the generation of secondary pollutants. This review examines the emerging potential of geopolymers as sustainable materials for microplastic remediation. Owing to their high porosity, chemical stability, tunable surface chemistry, and regenerative properties, geopolymers demonstrate considerable promise as both adsorbents and membrane materials. Extensive research has validated the efficacy of geopolymers in the removal of various environmental contaminants, including heavy metals and organic pollutants. For example, fly ash-based geopolymers modified with cetyltrimethylammonium bromide (CTAB) achieved a 98.2% removal efficiency for anionic acid blue 185 (AB185), while porous amorphous geopolymers synthesized from fly ash and iron ore tailings exhibited a copper (Cu²⁺) uptake capacity of 113.41 mg/g at 40 °C. These findings underscore the versatility of geopolymers in complex wastewater treatment applications. To date, only one direct study has explored geopolymer application in microplastic removal, demonstrating that silane-modified superhydrophobic geopolymer foam achieved up to 99% removal efficiency for polyethylene microspheres in wastewater. While this result highlights the feasibility of geopolymer-based microplastic remediation, dedicated research in this area remains sparse. This review consolidates existing knowledge on geopolymer interactions with other environmental pollutants to inform potential mechanisms for microplastic remediation. By drawing parallels between the removal of heavy metals and organic pollutants, this work identifies transferable principles and outlines research gaps necessary to advance geopolymer-based solutions for microplastic pollution. Overall, the findings affirm geopolymers' transformative potential in addressing microplastic contamination, while underscoring the urgent need for further experimental and field-based studies in this domain.