Lake Water Treatment Using Polyurethane-Polyvinylidene Fluoride Hollow Fiber Blend Membrane and Polyvinylidene Fluoride Hollow Fiber Membrane in a Coagulation-Microfiltration Process

2012 ◽  
Vol 518-523 ◽  
pp. 755-759
Author(s):  
Liang Wang ◽  
Bin Zhao ◽  
Shu Ling Ma ◽  
Hong Wei Zhang ◽  
Qin Yang

Polyurethane-polyvinylidene fluoride (PU-PVDF) hollow fiber blend membrane prepared by melting, spinning and drawing processes was used to treat lake water in a submerged coagulation-microfiltration (SCMF) process. This novel membrane is characterized by its elastic pore size increase with the pressure increase; therefore, the backwashing step could effectively remove the depositions stuck in membrane pores. Compared to the system using polyvinylidene fluoride (PVDF) hollow fiber membrane, the membrane anti-fouling ability was stronger in the system using PU-PVDF blend membrane, and the transmembrane pressure increased more slowly at a fixed permeate flux. Organic matters were removed comparably for both membranes during the first 3 h treatment, but those with benzene ring structures were susceptibly restricted by PU-PVDF blend membrane as the filtration went on. The turbidity removal was stable in the PU-PVDF system with an average of 97%, and was slightly higher than that in the PVDF system. The outstanding anti-fouling ability and excellent pollutant removal performance make the PU-PVDF hollow fiber blend membrane a better candidate for the SCMF process.

2013 ◽  
Vol 795 ◽  
pp. 137-140 ◽  
Author(s):  
Kok Chung Chong ◽  
Soon Onn Lai ◽  
K.M. Lee ◽  
Woei Jye Lau ◽  
B.S. Ooi

Membrane distillation (MD) is one of the novel separation methods used in water and wastewater treatment processes. MD is a thermal driven process which has the potential to be integrated with renewable energy source and can be operated at very low pressure. Polyvinylidene fluoride (PVDF) is a hydrophobic polymeric material which is commonly used to prepare MD membrane. In this study, surface modifying macromolecule (SMM) was added as additive into PVDF dope solution and then the hollow fiber membrane was prepared using phase inversion process. The membrane was characterized with respect to morphology and permeates flux at different temperatures. The results revealed that the PVDF membrane blended with SMM exhibited higher permeate flux than PVDF neat membrane did, mainly due to the better pore size distribution and thinner skin layer. This finding indicated the role of SMM in modifying the properties of PVDF membrane for MD process.


Author(s):  
S. A. Mousavi ◽  
Z. Arab Aboosadi ◽  
A. Mansourizadeh ◽  
B. Honarvar

Abstract Wetting and fouling have significantly affected the application of membrane distillation (MD). In this work, a dip-coating method was used for improving surface hydrophobicity of the polyetherimide (PEI) hollow fiber membrane. An air gap membrane distillation (AGMD) process was applied for treatment of the methylene blue (MB) solution. The porous PEI membrane was fabricated by a dry-wet spinning process and the hydrophobic 2-(Perfluoroalkyl) ethanol (Zonyl® BA) was used as the coating material. From FESEM, the modified PEI-Zonyl membrane showed an open structure with large finger-like cavities. The modified membrane displayed a narrow pore size distribution with mean pore size of 0.028 μm. The outer surface contact angle of the PEI-Zonly membrane increased from 81.3° to 100.4° due to the formation of an ultra-thin coated layer. The pure water flux of the PEI-Zonyl membrane was slightly reduced compared to the pristine PEI membrane. The permeate flux of 6.5 kg/m2 h and MB rejection of 98% was found for the PEI-Zonyl membrane during 76 h of the AGMD operation. Adsorption of MB on the membrane surface was confirmed based on the Langmuir isotherm evaluation, AFM and FESM analysis. The modified PEI-Zonyl membrane can be a favorable alternative for AGMD of dyeing wastewaters.


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