Synthesis, characterization, thermodynamic and kinetic investigations on uranium(Ⅵ) adsorption using organic-inorganic composites: Zirconyl-molybdopyrophosphate-tributyl phosphate

Zirconyl-molybdopyrophosphate-tributyl phosphate （ZMPP-TBP） was a novel organic-inorganic composite adsorbent prepared by co-precipitation method and used in the adsorption of uranium from aqueous solution in batch adsorption experiments The as-obtained product was characterized using SEM, energy dispersive X-ray spectroscopy （EDX）, XRD and BET-N2 ad- sorption measurements. The study had been conducted to investigate the effects of solution pH, temperature, contact time, ini- tial concentration and coexisting ions. A maximum removal of 99.31% was observed for an initial concentration 5 mg/L, at pH 6.0 and an adsorbent dose of 1.0 g/L. The isothermal data were fitted with both Langmuir and Freundlich equations, but the data fitted the former better than the latter. According to the evaluation using the Langmuir equation, the maximum adsorption capacity of uranium （VI） was 196.08 mg/g at 293 K and pH 6.0. The pseudo-first-order kinetic model and pseudo-second-order kinetic model were used to describe the kinetic data, and the pseudo-second-order kinetic model was better. The thermody- namic parameter AG was calculated, the negative AG values of uranium （VI） at different temperature showed that the adsorption process was spontaneous. The good reusability of ZMPP-TBP also indicated that the ZMPP-TBP was a very promising adsorbent for uranium adsorption from aqueous solution.

Zirconyl-molybdopyrophosphate-tributyl phosphate(ZMPP-TBP)was a novel organic-inorganic composite adsorbent prepared by co-precipitation method and used in the adsorption of uranium from aqueous solution in batch adsorption experiments.The as-obtained product was characterized using SEM,energy dispersive X-ray spectroscopy(EDX),XRD and BET-N2adsorption measurements.The study had been conducted to investigate the effects of solution pH,temperature,contact time,initial concentration and coexisting ions.A maximum removal of 99.31%was observed for an initial concentration 5 mg/L,at pH6.0 and an adsorbent dose of 1.0 g/L.The isothermal data were fitted with both Langmuir and Freundlich equations,but the data fitted the former better than the latter.According to the evaluation using the Langmuir equation,the maximum adsorption capacity of uranium(Ⅵ)was 196.08 mg/g at 293 K and pH 6.0.The pseudo-first-order kinetic model and pseudo-second-order kinetic model were used to describe the kinetic data,and the pseudo-second-order kinetic model was better.The thermodynamic parameterΔG was calculated,the negativeΔG values of uranium(VI)at different temperature showed that the adsorption process was spontaneous.The good reusability of ZMPP-TBP also indicated that the ZMPP-TBP was a very promising adsorbent for uranium adsorption from aqueous solution.