Highly efficient phosphate adsorption and interface interaction mechanism by UiO-66-COOH
Abstract
Phosphate-induced eutrophication poses a critical water quality concern, and adsorption offers an effective remediation approach, yet conventional adsorbents suffer from limited capacity and poor reusability. In this study, a carboxyl-functionalized zirconium-based metal-organic framework (UiO-66-COOH) was synthesized through the hydrothermal method and deeply explored its phosphorus removal performance and potential mechanisms. Batch adsorption experiments were conducted to investigate the effects of initial solution pH, initial phosphate concentration, adsorbent dosage, and reaction temperature on the material’s phosphate adsorption behavior. Under the optimized conditions (pH = 3, dosage 0.2 g l−1), UiO-66-COOH exhibited a remarkable removal efficiency of 97.71%, with an equilibrium adsorption capacity of 48.86 mg g−1. Adsorption kinetics followed the pseudo-second-order model, indicating chemisorption-dominated behavior, while thermodynamic analysis revealed a spontaneous and endothermic process. Comprehensive characterization (such as x-ray powder diffraction, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy) indicated that the efficient removal of phosphate by UiO-66-COOH was attributed to the synergistic effects of pore filling, carboxyl coordination chelation, and electrostatic interactions. This study not only provides an efficient adsorbent for phosphate pollution control but also offers theoretical and experimental support for the application of functionalized MOF materials in water environment remediation.