Zeolite-based materials for sulfate remediation: A review of structure–function insights, modification strategies, and sustainable water treatment applications

The widespread presence of sulfate (SO42−) in natural and industrial waters poses serious environmental and engineering challenges, including ecological degradation, scaling, and infrastructure corrosion. Conventional treatment methods such as chemical precipitation, ion exchange, biological reduction, and membrane separation are often limited by high energy consumption, secondary waste generation, or poor cost-effectiveness. Zeolites, crystalline aluminosilicates with highly ordered frameworks and ion-exchange capacity, have emerged as promising candidates for sulfate remediation. This review provides a critical assessment of natural, synthetic, and modified zeolites, with particular emphasis on how structural features and modification strategies influence adsorption performance. Surface modifications—such as cation exchange, acid activation, metal incorporation, and surfactant functionalization—are shown to significantly enhance sulfate affinity, stability, and reusability compared with raw zeolites. Mechanistic insights into ion exchange, electrostatic attraction, and surface complexation are systematically correlated with framework topology, pore dimensionality, and Si/Al ratios. Current challenges include regeneration efficiency, long-term structural stability under realistic wastewater conditions, and cost of large-scale synthesis and modification. Future directions highlight the importance of green synthesis approaches, the design of hybrid zeolite composites, and multifunctional zeolite-based platforms capable of simultaneously targeting anionic, cationic, and organic pollutants. By integrating structural chemistry with environmental engineering, this review establishes zeolites and their modified derivatives as sustainable and scalable materials for advanced sulfate remediation in water and wastewater systems.