| Membrane distillation,a membrane separation process based on hydrophobic microporous membrane,has attracted wide attention in water treatment in recent years.Due to its advantages of high separation efficiency,low operating temperature and low energy consumption,membrane distillation technology has broad application prospects in such fields as seawater desalination,separation concentration and wastewater treatment.The easy wettability and instability of membranes are the key factors affecting the large-scale application of membrane distillation technology.It was found that the preparation of a dense hydrophobic layer on the surface of the membrane is conducive to solving the wetting problem,and the duration of membrane distillation might be prolonged under the condition of ensuring the membrane distillation flux.In this work,a kind of dense hydrophobic skin was prepared by solution coating-curing method.The effects of coating times,coating solution concentration,coating and curing temperature on the structure and performance of the membranes were studied,and the silicone rubber/PVDF hollow fiber composite membrane was obtained.The stability of membrane distillation in the treatment of surfactant water was preliminarily discussed.The results showed that the uniform and stable composite membranes were prepared by solution coating-curing method.The pure water contact angle of the membrane was improved from 78°(PVDF membrane)to 149 °.When used in MD process for the treatment of solution containing sodium chloride and surfactant SDBS,the virgin PVDF membrane was leaking in about 20 minutes of experiment.While,the flux of the composite membrane was kept at about 36.6 kg/(m2·h)in 2 hours of continuous experiment with a permeate conductivity of 16.0 ?S/cm. |
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