Al(III)-based MOFs adsorbent for pollution remediation: Insights into selective adsorption of sodium diclofenac

The presence and persistence of pharmaceuticals in water affect human health, causing drug resistance and adverse effects on aquatic life. This study reports on the exceptional adsorption properties of Al(III)-based MOFs such as DUT-5 and MOF-303 for diclofenac sodium (DCF) remediation with remarkable chemical stability and cyclability. MOF-303 and DUT-5 displayed a maximum adsorption capacity of 334.89 and 103.36 mg g⁻¹, respectively. The adsorbents exhibited high chemical stability at different pH levels ranging from 4 to 10 during adsorption. In both MOFs, the adsorption kinetic data were based on the pseudo-second-order (PSO) model. DUT-5 showed faster adsorption due to the increased diffusion because of a large surface area for this MOF material. The adsorption isotherms followed the Temkin and Freundlich models for DUT-5 and MOF-303, respectively, which suggested the involvement of physicochemical forces in the adsorption mechanisms. Thermodynamic analysis proved the endothermic nature of the adsorption for both MOFs. Interaction mechanisms such as metal-π, π-π stacking, and electrostatic interaction were proposed based on the effect of pH and support by FTIR and XPS data. Therefore, both materials are viable adsorbing agents that may considerably impact pharmaceutical wastewater treatment; even MOF-303 showed higher adsorption capacity than different reported pristine and modified MOFs. This study also explores the facile synthesis of MOF materials with efficient adsorption behavior. It confirms the potential application of hydroxo-functionalized MOFs for the remediation of wastewater contaminated with DCF.