聚酰胺复合正渗透膜的制备及其脱盐性能研究

Fabrication of polyamide composite forward osmosis membranes and study on their desalination performance

通过溶液相转化法制备四种基膜,然后采用界面聚合法制备不同基膜的聚酰胺复合正渗透(FO)膜,并对其结构与性能进行表征。结果表明,正渗透膜基膜表面开孔率高、孔径分布均匀,且纯水通量大;在基膜中引入聚酯(PET)筛网使其厚度增大、孔隙率和纯水通量降低。基膜材料为聚砜(PSF)时,复合膜聚酰胺分离层较为疏松,以聚偏氟乙烯(PVDF)为基膜材料,形成的分离层较为致密且具有典型峰谷结构,从而使反向盐通量更小。四种复合膜的正渗透纯水通量均大于10 L/m2·h,最高达20 L/m2·h。120 min连续正渗透脱盐实验表明,复合膜截盐率及其稳定性优于商用膜,尤其PET筛网支撑PVDF基复合膜的截盐率基本稳定在97. 5%左右,表现出良好的运行可靠性。

Polyamide composite forward osmosis(FO)membranes were prepared on the top surface of 4 solution phase-inversion substrate membranes by interfacial polymerization,and the structure and performance of the substrate membranes and composite membranes were characterized.The prepared substrate membranes had high open surface with uniform pore size and high pure water flux;it raised the thickness and reduced the porosity,pure water flux to introduce polyester(PET)mesh into the substrate membranes.The results showed that the composite membranes with polysulfone(PSF)as the substrate material had looser active layer,and that of polyvinylidene fluoride(PVDF)had dense active layer with typical ridge-vally structure,which endowed the latter with lower reverse salt flux than the former.The FO pure water flux of the 4 composite membranes exceeded 10 L/m 2·h,with the highest at 20 L/m 2·h.Through the 120 min continuous FO desalination experiment,the prepared composite membranes had higher and more stable salt rejection than the commercial membrane.Especially,the PET mesh embedded PVDF based composite membrane showed well operational reliability,with stable salt rejection around 97.5%.