Application of PVDF membranes in desalination and comparison of the VMD and DCMD processes
Application of PVDF membranes in desalination and comparison of the VMD and DCMD processes
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DOI：
10.1016/j.ces.2012.05.052
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发表时间：
2012-09-10
影响因子：
4.7
通讯作者：
Peng, Yuelian
中科院分区：
文献类型：
--
作者：
Fan, Hongwei;Peng, Yuelian
膜蒸馏（MD）是一种有前景的海水淡化技术，可能有助于解决淡水短缺问题。疏水性平板聚偏氟乙烯（PVDF）膜被用于直接接触式膜蒸馏（DCMD）和真空膜蒸馏（VMD）工艺进行海水淡化。研究了操作条件的影响，例如热侧和冷侧的进料温度、流速以及进料溶液的浓度。在对35 g/L氯化钠水溶液进行DCMD处理过程中，热侧温度为73℃，冷侧蒸馏水温度为25℃时，渗透通量高达18.9 kg/m²·h，氯化钠截留率为99.8%。在相同进料温度和下游压力为31.5 kPa的VMD工艺中，渗透通量达到22.4 kg/m²·h，氯化钠截留率为99.9%。此外，在6小时的淡化试验中几乎没有任何润湿现象。采用 dusty gas模型成功预测了DCMD和VMD工艺中的渗透通量，并确定了通过膜的传质机制。在相同条件下对DCMD和VMD工艺中的通量和热效率进行比较，结果表明这种具有高表面疏水性和海绵状横截面的薄平板膜更适合用于VMD工艺而非DCMD工艺。（C）2012爱思唯尔有限公司。保留所有权利。
Membrane distillation (MD) is a promising desalination technology that may help to resolve the fresh water shortage. Hydrophobic flat-sheet polyvinylidene fluoride (PVDF) membranes were used for desalination by direct contact MD (DCMD) and vacuum MD (VMD) processes. The effect of the operating conditions, such as the feed temperature, flow velocity on both the hot and cold sides and the concentration of the feed solution were investigated. During the DCMD processing of a 35 g/L aqueous NaCl solution, with a hot side temperature of 73 degrees C and a cold distillate water temperature of 25 degrees C, the permeate flux was as high as 18.9 kg/m(2) h with a NaCl rejection of 99.8%. A permeate flux of 22.4 kg/m(2) h and a NaCl rejection of 99.9% were attained during the VMD process at the same feed temperature and a downstream pressure of 31.5 kPa. Furthermore, there was hardly any wetting during 6 h desalination test. A dusty gas model was used to successfully predict the permeating flux in both the DCMD and VMD processes, and the mass transfer mechanisms through the membrane were determined. Comparison of the flux and the thermal efficiency in the DCMD and VMD processes under the same conditions demonstrated that this type of thin flat-sheet membrane, which had a high surface hydrophobicity and a sponge-like cross-section, was more suitable for use in the VMD process than in the DCMD process. (C) 2012 Elsevier Ltd. All rights reserved.