科研之友
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摘要
The apparent permselectivity of a membrane is a critical ion transport property that influences the efficiency of electric field-driven membrane technologies and often is measured using a pseudo-steady-state measurement technique. In some cases, nonphysical apparent permselectivity values (greater than unity) are attributed to experimental uncertainty factors. The accuracy of the apparent permselectivity measurement can be influenced by variations in temperature, inaccurate solution concentrations, and fluctuations in membrane potential measurements, and these sources of uncertainty and their magnitudes were investigated both experimentally and using error analysis. Temperature had a small influence on the apparent permselectivity properties of two commercially available cation exchange membranes, as the value of the apparent permselectivity decreased by approximately 2% as the temperature increased from 14 to 31 degrees C. Membrane potential measurement fluctuations contributed approximately 0.2-0.5% uncertainty to the apparent permselectivity measurement. Deviations from target sodium chloride solution concentrations of 10 ppm introduced approximately 0.015-0.1% error, respectively, in apparent permselectivity. The magnitudes of these uncertainties typically are comparable to the magnitude of the measurement variability associated with disassembling and reassembling the measurement cell between replicate measurements made on the same sample, so the overall influence of the experimental factors considered in this study on apparent permselectivity is expected to be generally small.
- 出版日期2017-7-5
