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利用涂覆交联的方法,以羧甲基纤维素钠(CMC)和聚丙烯酸钠(PAAS)的共混液为活性层铸膜液,水解的聚丙烯腈(PAN)超滤膜为支撑层,Fe(NO_3)_3水溶液为交联剂,制备了一种新型共混复合纳滤膜。其最佳制备条件为:CMC/PAAS共混质量比为4∶1,交联剂浓度为0.125 mol/L,交联时间为2.5 h。利用全反射红外光谱(ATR-IR)、扫描电镜(SEM-EDAX)对膜结构进行表征。结果表明,Fe~(3+)能够有效地交联活性层与支撑层,形成结构稳定的纳滤膜。纳滤膜对无机盐的截留按以下顺序依次降低:Na_2SO_4、Na Cl、Mg SO_4、Mg Cl_2,表现出荷负电纳滤膜的截留特征。在连续运行24 h后,纳滤膜的纯水通量仍可达到7 L/m~2·h,截留率约为85%,显示了较好的稳定性能。
The coating cross-linking method was used, the coating solution of sodium carboxymethyl cellulose (CMC) and sodium polyacrylate (PAAS) was used as the active layer casting solution and the hydrolyzed polyacrylonitrile (PAN) Fe (NO_3) _3 aqueous solution as a cross-linking agent to prepare a new type of composite nanofiltration membrane. The optimum preparation conditions were as follows: the mass ratio of CMC / PAAS was 4:1, the concentration of crosslinking agent was 0.125 mol / L and the crosslinking time was 2.5 h. The membrane structure was characterized by total reflection infrared spectroscopy (ATR-IR) and scanning electron microscopy (SEM-EDAX). The results show that Fe 3+ can effectively crosslink the active layer and the support layer to form a stable nanofiltration membrane. The entrapment of inorganic salts by nanofiltration decreased in the following order: Na_2SO_4, NaCl, MgSO_4 and MgCl_2, showing the rejection characteristics of negative charged nanofiltration membrane. After continuous operation for 24 h, the pure water flux of the nanofiltration membrane can still reach 7 L / m ~ 2 · h, and the rejection rate is about 85%, showing a good stability.