Effects of PVDF-HFP concentration on membrane distillation performance and structural morphology of hollow fiber membranes



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García Payo, María del Carmen and Essalhi, M. and Khayet Souhaimi, Mohamed (2010) Effects of PVDF-HFP concentration on membrane distillation performance and structural morphology of hollow fiber membranes. Journal of membrane science, 347 (01-feb). pp. 209-219. ISSN 0376-7388

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Official URL: http://dx.doi.org/10.1016/j.memsci.2009.10.026


Poly(vinylidene fluoride-hexafluoropropylene), PVDF-HFP, hollow fiber membranes were prepared by the dry/wet spinning technique using different copolymer concentrations in the dope solutions ranging from 17 to 24 wt.%. All the spinning parameters were maintained constant except the copolymer concentration. The morphological properties of the hollow fiber membranes were studied in terms of scanning electron microscopy (SEM), atomic force microscopy (AFM) and void volume fraction. The effects of PVDF-HFP content in the spinning solutions were also studied by measuring the water entry pressure and direct contact membrane distillation (DCMD) permeate flux of the hollow fiber membranes. An increase in the copolymer concentration of the spinning solution resulted in a decrease in the precipitation rate and a transition of the cross-section structure from a finger-type structure to a sponge-type structure. Pore size, nodule size and roughness parameters of both the internal and external hollow fiber surfaces were determined by AFM. It was observed that the pore size decreased in both the internal and external surfaces of the hollow fiber membranes with increasing the copolymer concentration and reached a minimum value at the outer surface for PVDF-HFP concentrations greater than 20 wt.%. Water entry pressure values were decreased whereas both the void volume fraction and the DCMD permeate flux increased with decreasing the copolymer concentration.

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© 2009 Elsevier B.V. The authors gratefully acknowledge the financial support of the Spanish Ministry of Science and Education (MEC) (Project FIS2006-05323) and the UCM-BSCH (Project GR58/08, UCM group 910336). M. Essalhi is thankful to the Middle East Desalination Research Centre for the grant (MEDRC 06-AS007).

Uncontrolled Keywords:Aqueous alcohol-solutions; Poly(vinylidene fluoride); Air-gap; Mechanical-properties; Separation process; Size Distribution, Acid Solutions, Water, Ultrafiltration, Desalination
Subjects:Sciences > Physics > Thermodynamics
ID Code:26349
Deposited On:23 Jul 2014 11:18
Last Modified:05 Nov 2015 14:12

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