Acid-modulated zirconium based metal organic frameworks for removal of organic micropollutants

Abstract

UiO-66 is one of the most applied metal organic frameworks on environmental remediation. In this study, UiO-66 was prepared and modified it by acid treatment. Acid treatment causes defected sites in the crystals. These defected sites provide increasing the adsorption capacities of crystals. The surface properties of prepared UiO-66 crystals were examined by X-ray diffraction spectroscopy (XRD), Fourier transform Infrared spectroscopy (FTIR), BET surface area analysis, particle size distribution analysis, and Scanning electron microscopy (SEM), respectively. 2,4-dichlorophenoxy acetic acid (2,4-D), ciprofloxacin (CPX) and naproxen (NPX) were adsorbed on UiO-66 crystals. Some adsorption variables were examined. These variables are amount of adsorbent, pH of adsorbate solution, initial adsorbate concentration, and contact time. The equilibrium times were determined as 120 min for 2,4-D, 45 min for CPX and 120 min for NPX. Pseudo second order (PSO), fractional power and Elovich kinetic models were calculated. Additionally, Langmuir, Freundlich, Sips and Radke-Prausnitz isotherms were also calculated. PSO kinetic model has been suited the adsorption of all three micropollutants. Langmuir isotherm has been fitted to 2,4-D, CPX and NPX adsorption. The calculated maximum adsorption uptake values of 2,4-D, CPX and NPX are 370.37, 111.71 and 43.86 mg/g, respectively.