Zinc oxide impregnated resin for preconcentration and spectrophotometric determination of uranyl ions in aqueous solutions

The objective of this work is to find a new, efficient and alternate low-cost adsorbent for preconcentration and spectrophotometric determination of uranyl ions U(VI) from aqueous solution. For this reason the new impregnated resin (ZnO/7HP) has been prepared by sol-gel technique. Characterization of ZnO/7HP was conducted using scanning electron microscopy/energy-dispersive X-ray spectrometer and X-ray diffraction, and Fourier transforms infrared spectroscopy. Several important parameters influencing the U(VI) adsorption such as pH, adsorbent amount, initial U(VI) concentration, contact time and temperature were investigated systematically by batch experiments. The obtained results showed that the equilibrium adsorption data were well fitted to the Langmuir model with a maximum adsorption amount of 24.96 mg/g. While the adsorption kinetics data were described well by the pseudo-second order model. This result indicates that the adsorption process is chemisorption. Thermodynamic results indicate that the U(VI) adsorption process is endothermic nature and favors at high temperature. Hydrochloric acid was used for preconcentration of U(VI) and detected spectrophotometry after the reaction with Arsenazo III. According to the definition of International Union of Pure and Applied Chemistry, the detection limit of this method was 0.12 μg/L. The relative standard deviation under optimum conditions is less than 3.0 % (n=5). The new impregnated resin ZnO/7HP is a promising adsorbent for preconcentration and spectrophotometric determination of U(VI) in aqueous solutions.