Hybrid nanocomposites of zeolite with MOFs, CNTs, graphene, and polymers for wastewater treatment: a comprehensive review

Abstract

The increasing discharge of inorganic, organic, and emerging contaminants into aquatic environments continues to challenge conventional wastewater treatment systems and highlights the need for efficient, selective, and regenerable adsorbents. Zeolites have been widely investigated for water purification because of their porous aluminosilicate frameworks, ion-exchange capacity, structural stability, and low-cost availability. However, pristine zeolites may show limited affinity toward some organic pollutants, restricted accessibility of active sites, and reduced performance in complex wastewater matrices. To overcome these limitations, recent studies have developed zeolite-based hybrid nanocomposites by integrating zeolites with carbon nanotubes (CNTs), graphene-based materials, polymers, and metal–organic frameworks (MOFs). This review critically examines the synthesis, adsorption performance, mechanisms, regeneration and reuse behavior, environmental risks, and practical challenges of these hybrid adsorbents for removing heavy metals, dyes, phenols, pharmaceuticals, antibiotics, nutrients, and other pollutants. A scientometric analysis was also conducted to evaluate publication trends, major contributing countries, influential journals, and dominant research themes. A total of 400 publications retrieved from the Scopus database were analyzed to identify emerging research directions, material-development trends, and existing knowledge gaps. Particular attention is given to adsorption mechanisms, including ion exchange, electrostatic attraction, surface complexation, hydrogen bonding, π–π interactions, pore filling, hydrophobic interactions, and coordination-based binding. The effects of operating parameters, adsorption kinetics, isotherms, and thermodynamics are also discussed. Although zeolite-based hybrid nanocomposites often provide improved adsorption performance and broader pollutant affinity, their practical application remains constrained by synthesis cost, regeneration efficiency, nanomaterial stability, environmental safety, and limited testing under realistic wastewater conditions. Future studies should prioritize scalable synthesis, regeneration assessment, toxicity evaluation, and continuous-flow performance.