Woźniak Piotr, Gryta Marek
Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, ul. Pułaskiego 10, 70-322 Szczecin, Poland.
Membranes (Basel). 2023 Jan 8;13(1):80. doi: 10.3390/membranes13010080.
In the present study, the membrane distillation (MD) process was studied with the use of commercial polytetrafluoroethylene (PTFE) capillary membranes. For this purpose, both solutions with NaCl concentrations up to 300 g/L and brines contaminated with oil (70-120 mg/L) were used as feeds. The membrane's wetting resistance was tested by conducting long-term experiments for over 3500 h. Using detailed studies, it has been shown that increasing the salt concentration from 35 to 300 g/L resulted in a 50% reduction in the permeate flux. Nevertheless, the membranes retained 100% of the salt rejection after 2000 h of the module's operation. Moreover, it has been found that performing the MD process with brines contaminated with oil (120 mg/L) led to the wetting of some membranes pores, which it turn resulted in an increase in the distillate's conductivity to 450 µS/cm after 700 h running the process. The mechanism of pore wetting by oil droplets adsorbed on the membrane's surface was presented. Finally, the proposed method of membrane cleaning with the use of a solvent allowed restoring the initial MD module's performance. Consequently, both the permeate flux and distillate conductivity were stable during the MD of the feed containing 35 g/L of NaCl over the next 280 h.
在本研究中，使用商用聚四氟乙烯（PTFE）毛细管膜对膜蒸馏（MD）过程进行了研究。为此，将NaCl浓度高达300 g/L的溶液以及被油污染（70 - 120 mg/L）的盐水用作进料。通过进行超过3500小时的长期实验来测试膜的抗润湿性。通过详细研究表明，将盐浓度从35 g/L提高到300 g/L会导致渗透通量降低50%。然而，在模块运行2000小时后，膜对盐的截留率仍保持100%。此外，还发现用被油污染（120 mg/L）的盐水进行MD过程会导致一些膜孔被润湿，这进而导致在该过程运行700小时后馏出液的电导率增加到450 μS/cm。提出了膜表面吸附的油滴使膜孔润湿的机制。最后，所提出的使用溶剂清洁膜的方法能够恢复初始MD模块的性能。因此，在接下来的280小时内，在含有35 g/L NaCl的进料进行MD过程中，渗透通量和馏出液电导率均保持稳定。
