低压条件下双甘膦NaCl混合溶液的纳滤分离性能研究

STUDY ON THE SEPARATION PROPERTY OF N-PHOSPHONOMETHYLIMINODIACETIC ACID (PMIDA),NaCl FROM THE SIMULATED SOLUTION BY THE NANOFILTRATION

选择纳滤膜NF270对双甘膦和NaCl自配混合溶液进行分离试验研究和理论分析。探讨了pH、操作压力、氯化钠浓度、双甘膦浓度对纳滤膜分离性能的影响。结果表明,由于纳滤膜NF270截留分子量小于双甘膦分子量,孔径筛分效应成为双甘膦截留率的决定性因素,截留率均稳定在97%左右。电荷效应对NaCl截留率与膜通量有着显著的影响,在pH为6.2,压力为0.7 MPa时NaCl截留率达到最低值4.5%,而高浓度氯化钠不利于分离,高浓度双甘膦却有助于二者的分离。结论认为运用NF270在适宜的操作条件下可实现双甘膦和氯化钠的最大分离。

NF270 nanofiltration membrane was selected to the separation of PMIDA and NaCl mixture prepared by ourselves and the theoretical analysis was conducted at the same time.The pH value,operating pressure,sodium chloride content and PMIDA concentration which effected on the separation performance of nanofiltration membranes were discussed.The results showed that because of the molecular weight cut-off of the NF270 was less than PMIDA,the pore sieving effect became the decisive factor in the rejection and the rejection rates steady at about 97%.Charge effect had a significant effect on NaCl rejection and flux.The NaCl rejection rate reached the minimum 4.5% when the pH at 6.2 under the pressure of 0.7 MPa.The high concentration of sodium chloride was not conducive to separation while the high concentrations of PMIDA was on the opposite.The results showed that the use of NF270 in the appropriate operating conditions can achieve the best separation of PMIDA and NaCl mixture.