Study Of Membrane Wetting In The Process Of Membrane Distillation

For its lower energy consumption, high selectivity and operation at ambienttemperature, membrane distillation has been more and more widely used inthe separation technology, such as fruit juice and traditional Chinese medicineconcentration. However, if the feed-side solution includes surfactant, thehydrophobic membrane used in membrane distillation may be wetted, whichcan influence membrane distillation both on quality and quantity. While, mostof present researches are about CO2absorption; the membrane wetting inmembrane distillation is rarely studied now.In this study, the influence of surfactant on the membrane wetting and thetrans-membrane flux in membrane distillation is investigated by sodiumdodecyl benzene sulfonate(SDBS). Furthermore, the effect of SDBS massfraction and temperature on the membrane wetting; and the resist-wettabilityof polyvinylidene fluoride(PVDF) and polytetrafluoroethylene(PTEE) is alsocompared. The results indicate that, with a certain wetting time, the depth ofmembrane wetting increases with the increase of SDBS mass fraction andtemperature, which also makes the trans-membrane flux decrease more rapidly.The resist-wettability of PTEE is better than PVDF. Additionally, the influence of membrane swelling effect caused by someorganic solution on the trans-membrane flux during the process of membranedistillation and this effect on the trans-membrane flux were also studied byalcohol and limonene. The results show that with lower concentration, themembrane swelling more serious with the increase of mass fraction, whichalso increases the depth of membrane wetting; while, with higherconcentration, the depth of membrane wetting and membrane swelling arealmost independent with mass fraction. Moreover, membrane with larger poresize swells more serious and the resist-swelling of PTEE is better than PVDF.At last, the trans-membrane flux of solution with wetting components inthe process of membrane distillation is estimated by a semi empirical theorymodel.