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以浓盐水为研究对象,选取进料液温度、真空度、进料液流速、超声频率和超声功率5个影响因素,对超声强化减压膜蒸馏工艺中膜通量的影响进行实验研究。实验结果表明:浓盐水超声强化减压膜蒸馏工艺的最佳操作条件为:进料液温度75℃,真空度0.080 MPa,进料液流速1 741 cm/min,超声频率40 k Hz,超声功率500 W。对聚丙烯(PP)和聚四氟乙烯(PTFE)两种中空纤维膜进行平行操作条件比对,证明聚丙烯(PP)的膜通量优于四氟乙烯(PTFE)。实验还对最优操作条件下的膜通量衰减规律以及膜表面污染情况进行了分析,表明PP膜的膜通量随时间的延长呈现出一定程度的衰减,当实验装置连续运行1 200 min后,出水电导率从最初的10μs/cm逐渐增加到3 ms/cm,截留率从最初的99.98%下降到96.40%。通过扫描电镜-能谱分析膜表面污染元素为Si、Al、Ca、Mg、Fe、Na、Cl、K等常见海水元素,结晶物主要为CaCO3和NaCl。综上所述,利用超声强化减压膜蒸馏工艺进行浓盐水资源化,具备技术可行性和良好的应用前景。
Taking concentrated brine as the research object, five influencing factors of feed liquid temperature, vacuum degree, feed liquid flow rate, ultrasonic frequency and ultrasonic power were selected to study the influence of membrane flux in ultrasonic enhanced vacuum membrane distillation process. The experimental results showed that the optimum operating conditions of the ultrasonically evacuated membrane distillation process were as follows: feed temperature 75 ℃, vacuum 0.080 MPa, feed liquid flow rate 1 741 cm / min, ultrasonic frequency 40 k Hz, ultrasonic power 500 W. The parallel operation of two kinds of hollow fiber membranes, polypropylene (PP) and polytetrafluoroethylene (PTFE), showed that the membrane flux of polypropylene (PP) was superior to that of tetrafluoroethylene (PTFE). At the same time, the law of membrane flux decay and membrane surface contamination under the optimal operating conditions were also analyzed. The results showed that the membrane flux of PP membrane showed a certain degree of attenuation with time. When the experimental device operated continuously for 1200 min , The water conductivity gradually increased from the initial 10μs / cm to 3ms / cm, the rejection decreased from the initial 99.98% to 96.40%. By scanning electron microscopy - energy dispersive spectroscopy analysis of membrane surface contamination elements of Si, Al, Ca, Mg, Fe, Na, Cl, K and other common seawater elements, mainly CaCO3 and NaCl. In summary, the use of ultrasonic enhanced vacuum membrane distillation process for the reclaimed brine, with technical feasibility and good application prospects.