The novel performance and adsorption mechanism of synthesized modified zirconium-based metal-organic frameworks for resource recovery from wastewater

Phosphorous (P) is an indispensable nutrient popularly employed to fertilize agricultural farms. However, its overuse in farming leads to excessive discharge in agricultural runoff, causing eutrophication. To prevent harm to the environment, it is necessary to remove P from wastewater. Adsorption is one of the ways to achieve this goal. In this study, using a solvothermal process, UiO-66-NH₂ was successfully modified/codoped with aluminum (Al) and magnesium (Mg). The Al/Mg-codoped UiO-66-NH₂ was characterized using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The study also investigated various adsorption factors, including temperature, pH, initial phosphate concentration, sorbent dosage, reaction time, and coexisting components. The findings demonstrated that the sorption process was predominantly based on chemical interactions, as evidenced by the Langmuir model (R² > 0.99) and pseudo-second order (R² > 0.99) analyses that fit well with experimental findings. The sorption capacity value was determined to be 117.6 mg P/g or 360.73 mg PO₄/g. Thermodynamic results suggested the spontaneous and endothermic nature of P uptake process. Additionally, this research demonstrated the effective utilization of adsorbent for up to six regeneration cycles and recovery of adsorbed P using sodium hydroxide.