Challenging the Surface Area Paradigm: A Critical Review of Low-BET Metal-Organic Frameworks for the Adsorption of Organic Water Pollutants.

The application of metal-organic frameworks (MOFs) toward the adsorption of organic pollutants from aqueous systems has attracted heightened attention in recent times. While considerable research works have examined high-surface-area MOFs, growing evidence demonstrates that MOFs with low Brunauer-Emmett-Teller (BET) surface areas (SBET ≤ 100 m2/g) can also achieve remarkably high pollutant adsorption. This review critically examines, for the first time, recent developments that have enabled low-surface-area MOFs to adsorb organic pollutants from wastewater efficiently. The first part explores compositional modifications of low-surface-area MOF adsorbents, with particular attention to their metal centers. Furthermore, four categories of auxiliary components were delved into. Additionally, the factors influencing adsorbent synthesis were presented. Moreover, low- and high-SBET MOFs were directly compared. Finally, current challenges and key research gaps were identified. Future research priorities such as rigorous mechanistic validation, performance evaluation in realistic water matrices, improved regeneration strategies, and advancing pilot-scale studies to facilitate practical application were also presented.