温度对分光光度法测定超滤膜性能的影响

以分光光度法中的碘沉淀法为实验体系, 取聚乙二醇(PEG)为标准物质, 考察温度变化对分光光度法测定超滤膜截留分子质量、平均孔径以及孔径分布的影响. 结果表明, 当各个分子质量的PEG质量浓度一定时, 随着温度升高, 其吸光度减小. 温度对高质量浓度区间(>4mg?L-1)PEG吸光度的影响较大, 以PEG宽质量浓度区间(2~10mg?L-1)作标准曲线为基准, 温度升高时, 所测膜截留分子质量显著增加, 平均孔径增大, 膜孔径分布变宽. 温度对低质量浓度范围(<4mg?L-1) PEG吸光度的影响较小, 以PEG低质量浓度区间作标准曲线为基准, 各个温度条件下所测膜截留分子质量、平均孔径及膜孔径分布基本不变. 通过配制低质量浓度PEG溶液作标准曲线或将PEG渗透液稀释到低质量浓度区间进行吸光度测试可减小温度对分光光度法测定超滤膜性能的影响.

Effect of temperature on ultrafiltration membrane performance detected by spectrophotometric method

Based on the method of iodine precipitation, we investigate the effect of temperature on evaluating the molecular weight cut off (MWCO), the mean pore size and pore size distribution of ultrafiltration membrane by spectrophotometric method. The results show that for the certain concentration of PEG solution, the absorbance of PEG gradually decreases as the temperature increases. It is found that the variation of temperature obviously influences the absorbance of PEG under high concentration condition (>4mg?L-1). Based on PEG standard curve in wide concentration range (2-10mg?L-1), the MWCO grows more significantly, while the mean pore size increases and so does the pore size distribution with the temperature increasing. However, the variation of temperature has less effect on the absorbance of PEG under the low concentration condition (<4mg?L-1). Judging by the PEG standard curve in lower concentration range, the MWCO, the mean pore size and the pore size distribution remain almost unchanged at different temperature. The effect of temperature on the ultrafiltration membrane performance detected by the spectrophotometric method can be reduced using PEG standard curve in lower concentration range or diluting permeated solution to the low concentration range before testing its absorbance.