分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The electrochemical behavior of Pd(II) and Rh(III) in [EMIm]NTf2 ionic liquid has been studied on Pt working electrodes at 298 K by cyclic voltammetry (CV), polarization curve and galvanostatic transient techniques. Cyclic voltammogram of Pd(II) in [EMIm]NTf2 consists of two cathodic current peaks located at 1.37 V(Epc2), corresponding to Pd2+/Pd+, and at 0.69 V (Epc1) corresponding to Pd+/Pd. The transfer coefficient was calculated by the Tafel extrapolation from the polarization curves to be 0.306, which is in agreement with the value reported in an aqueous solution system. For Rh(III) in [EMIm]NTf2, a cathodic current peak (Epc) was observed at -0.39 V, corresponding to Rh3+/Rh, and two oxidation peaks were observed at -0.13 V (Epa1) and 0.37 V (Epa2) during the reverse scan. A significantly negative shift in the cathodic peak potential was observed with the increase of the scan rate, indicating that the reduction of Pd(II) and Rh(III) on the Pt electrode involves kinetic complications. By using the galvanostatic transient technique, the diffusion coefficients of Pd(II) and Rh(III) in [EMIm]NTf2 ionic liquid solution were found to be 10-7 cm2/s. The potential difference between the reduction of Pd(II) to Pd and the reduction of Rh(III) to Rh obtained from the CV curves of the Pd(II) and Rh(III) co-existing [EMIm]NTf2 solution is found to be about 0.74 V, which makes it possible to electrodeposit Pd(II) and Rh(III) separately.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The adsorption behavior of 241Am(III) and Eu(III) by silica/polymer-based isoHex-BTP adsorbent (isoHex-BTP/SiO2-P) was investigated by a batch experiment method. isoHex-BTP/SiO2-P exhibited high affinity and selectivity for 241Am(III) over 152Eu(III) in 24 mol/dm3 nitric acid solutions. Within the experimental contact time range of 0.524 h, isoHex-BTP/SiO2-P showed high selectivity for 241Am(III) compared to 152Eu(III) in 3 mol/dm3 nitric acid solution. However, the adsorption kinetics of 241Am(III) and 152Eu(III) was slow. Eu(III) adsorption followed the pseudo-second-order kinetic model, indicating chemical adsorption as the rate-limiting step of the adsorption process. And the adsorption agreed well with the Langmuir adsorption model at various temperatures. The adsorption kinetics and isotherm data indicated that the equilibrium adsorption capacity, the adsorption rate, the maximum adsorption capacity and the adsorption affinity, increased with temperature. The thermodynamic parameters, negative change in Gibbs free energy, and positive change in enthalpy and entropy, suggested that the adsorption of Eu(III) was spontaneous and endothermic process with an increase of entropy.
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