一种用于从水中分离挥发性有机化合物的疏水性渗透汽化中空纤维复合膜

研制出一种名为VOC-SEP200新型中空纤维疏水性复合膜，并考察了这种复合膜从水中分离BTEX(苯、甲苯、乙苯和二甲苯)的性能．这4种芳香碳氢化合物是工业有机废水中的一组有代表性的污染物，本研究的最终目的是想从现实的工业废水中回收这些化合物．采用料液在纤维中孔流动的方式，系统考察了进料液流速、操作压力、温度和进料液浓度对膜分离效率及膜性能的影响．结果显示，随着进料液流速的提高，BTEX的通量随之增大．这是由于随着进料液流速的提高，浓度极化的影响会减少，同时BTEX和水的分离因子会有显著增大．结果还显示，膜的性能随膜横向的驱动力降低而提高，其最佳的渗透压范围是10．7～13．3kPa(即80～100mmHg)，此时BTEX通量达到最大平稳值，同时水的通量最小．提高渗透压可减少操作费用，同时可增强分离效果，和预期的情况一样，BTEX和水的渗透通量都随着温度和进料浓度的提高而增大，但再进一步提高浓度和温度，则对水通量不产生影响．水通量在初始阶段的增加可以归因于膜的溶胀，水通量不再随温度和浓度的进一步升高而增加，可以归因于水分子的聚集与膜的溶胀达到了平衡，

A composite organophilic hollow fiber membrane-based pervaporation process for separation of VOCs from water

A new composite organophilic hollow fiber membrane has been developed and the membrane product is known as VOC-SEP 200. The separation of the mixture of BTEX (benzene, toluene, ethyl benzene and xylene) (representative of an industrially significant family of aromatic hydrocarbon chemicals produced from industrial wastes) from water using the newly developed composite membrane was investigated, having an ultimate objective of recovering these compounds from the real industrial wastes. In this study, the permeation process employed bore-side feed flow. The influence of feed-solution velocity, permeate pressure, temperature and feed concentration on the membrane separation efficiency and performance were also systematically investigated. The BTEX flux was found to increase with increase in feed-solution velocity. This is partly due to reduction in concentration polarization effect, and thus also resulting in dramatic increase in BTEX/water separation factor with increasing feed-solution velocity. The performance of this membrane has been found to improve as the driving force across the membrane decreases. That is, the optimum permeate pressure is in the rang 10.7～13.3 kPa,i.e.,80～100 mmHg, when the BTEX flux is still at its maximum plateau value and the water flux is small. Increasing the permeate pressure reduces the operating cost while the separation is enhanced. As expected, the permeation fluxes of both BTEX and water was found to increase with increase in temperature and feed concentration and independence in water flux is achieved with further increase in concentration/temperature. The increase in water flux could be attributed to plasticization/swelling of the membrane and a near plateau value obtained at high concentration/temperature could be attributed to the effect of water clustering being balanced with the enhancement of permeant diffusion or membrane mobility (due to plasticization/swelling effect).