印染废旧膜清洗对再生膜的影响研究

Study on the Effect of Dyeing Waste Membrane Cleaning on Regenerated Membrane

以印染废水处理工程产生的废旧聚偏氟乙烯(PVDF)中空纤维膜为原材料,通过酸、碱、氧化剂和阴离子表面活性剂以不同的清洗方案对其进行清洗、N,N-二甲基乙酰胺(DMAc)溶解回收、非溶液致相分离(NIPS)制备了再生平板膜。对比了不同清洗方案制备的再生膜和新膜的形貌、分离性能和机械强度,发现再生膜的孔隙率均低于新膜,碱和氧化剂会导致再生膜孔径变大18%~72%,纯水通量上升20%,应力和应变性能分别下降34%和19.9%。酸和十二烷基苯磺酸钠(SDBS)对孔径的影响可忽略,后者会增强膜表面的电负性从而通过静电作用排斥污染物。SDBS引起PVDF的脱氟化氢反应要强于碱和氧化剂,使PVDF的α相向β相转变,纯水通量下降14%,并且会一定程度地增强再生膜的应变性能。再生膜对污染物的截留主要依赖孔径筛分。

Using the waste polyvinylidene fluoride(PVDF)hollow fiber membranes from the printing and dyeing wastewater treatment project as the raw material,the regenerated flat membranes were prepared by combining acid,alkali,oxidant and anionic surfactant in different schemes for the cleaning of waste membranes,N,N-dimethylacetamide(DMAc)dissolution and recovery,and non-solution-induced phase separation(NIPS).The morphology,separation performance and mechanical strength of the regenerated and new membranes prepared by different cleaning schemes were compared.It is found that the porosity of the regenerated membrane is lower than that of the new membrane.Alkali and oxidant could increase the pore size of regenerated membrane by 18%-72%,increase the pure water flux by 20%,and decrease the stress and strain performance by 34%and 19.9%,respectively.Acid and sodium dodecyl benzene sulfonate(SDBS)on the influence of aperture can be neglected.The latter can enhance the electronegativity of the membrane surface and thus repel contaminants by electrostatic repulsion.The hydrogen defluorination reaction of PVDF caused by the SDBS is stronger than that of alkali and oxidant,resulting in a shift from theαphase to theβphase of PVDF,a 14%drop in the pure water flux,and a certain degree of enhance regeneration membrane strain performance.The retention of contaminants by regenerated membrane mainly depends on pore size screening.