A critical review of structural-functional-mechanistic advances in molecular sieve ceramic composite membranes for wastewater treatment and resource recovery

Molecular sieve ceramic composite membranes (MSCCMs) enable molecular-scale separation. This precision is essential for recovering resources from wastewater. In these tasks, polymeric membranes often fall short. This review provides a critical and systematic analysis of MSCCMs through the lens of structure, function, and mechanism. We first classify MSCCMs by their active components. These include MOFs, COFs, nanoparticles, and photocatalysts or functional materials. We then critically evaluate their synthesis and immobilization strategies. Conventional methods such as sol-gel, hydrothermal, coating, electrospinning, template, and dry pressing are discussed. Emerging techniques including CVD, UV photopolymerization, radio-frequency magnetron sputtering, 3D printing, and auxiliary fields are also examined. Next, we examine the coupled separation and recovery mechanisms. These mechanisms are size exclusion, Donnan effect, intermolecular forces, redox reactions, bioaffinity, and dynamic layer formation. We link these mechanisms to structural features and antifouling design. Machine learning is highlighted as an emerging tool for predicting performance, fouling, and long-term stability. Despite higher initial costs, MSCCMs offer superior durability and lower lifecycle costs. Persistent challenges include fabrication cost, interfacial delamination, fouling, and regeneration of the molecular sieve layer. To move beyond lab-scale demonstrations, we propose three priority directions. The first is materials innovation, which includes water-stable sieves, waste-derived supports, and smart coatings. The second is process intensification, such as low-temperature sintering and advanced shaping. The third is digital integration, using machine learning for autonomous control and lifetime prediction. This framework accelerates rational design and practical deployment of next-generation MSCCMs for sustainable wastewater treatment and resource recovery.