Translated Title
Study on the wetting mechanism of different types of surfactants in negative pressure membrane distillation
Translated Abstract
Wetting due to surfactants was a major problem in membrane distillation when treating real wastewater.In order to alleviate membrane wetting,a negative pressure direct-contact membrane distillation(DCMD)process was used to evaluate the membrane performance when different surfactant saline solutions were the feed,and the wetting mechanism was analyzed through scanning electron microscopy,dynamic light scattering technology and other techniques.First,0.1 × 10-3 mol/L SDS,CTAB,and Tween-20 surfactant saline solutions were respectively treated in a negative pressure DCMD.The results showed that when SDS saline solution was treated,the membrane flux was stable,and the permeate conductivity remained 3 μS/cm.For CTAB and Tween-20 saline solution,the membrane flux decayed and negative flux existed.By analyzing the foulant on the membrane surface and the micelle size in the solution,it was confirmed that cationic and nonionic surfactant micelles deposited and fouled the membrane surface,causing membrane wetting.In order to explore the relationship between membrane fouling and critical micelle concentration,saline solutions with 0.1CMC,0.5CMC,1.0CMC surfactant content were tested.The critical micelle concentrations(CMC)of SDS,CTAB,and Tween-20 were 9.6× 10-3 mol/L,9.1 × 10-5 mol/L and 6 × 10-5 mol/L,respectively.The results showed that the membrane flux remained stable when 9.1×10-6 mol/L CTAB(0.1CMC)and 6×10-6 mol/L Tween-20(0.1CMC)saline solutions were treated.However,for SDS saline solution,the membrane flux decreased.The main reason was that the critical micelle concentration of SDS(9.6×10-3 mol/L)was two orders of magnitude higher than the other two surfactants,and it also had a higher hydrophilic-lipophilic balance value(40),9.6X10 4 mol/L SDS(0.1CMC)saline solution had a lower surface tension(26.4 mN/m),leading to membrane wetting.
Translated Keyword
membrane wetting
surfactant
negative pressure membrane distillation
critical micelle concentration
membrane fouling
Access Number
WF:perioarticalmkxyjs202401002
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