Omniphobic Polyvinylidene Fluoride (PVDF) Membrane for Desalination of Shale Gas Produced Water by Membrane Distillation

Membrane distillation (MD) is a thermally driven separation process. Despite many advantages over other membrane separation processes, pore wetting hampers the wide commercial applications of the MD process. In this paper, the effect of temperature and presence (or absence) of salt in the feed solution on the wetting properties of commercial polyvinylidene fluoride (PVDF) membrane during a period of eight weeks was investigated. Liquid entry pressure (LEP) and water contact angle (WCA) were employed to characterize the wetting properties of the PVDF membrane. The result shows that the temperature has a significant impact on the decrease of the contact angle of the PVDF membrane.

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Surface Modification of PVDF Membranes for Treating Produced Waters by Direct Contact Membrane Distillation

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16050685 ◽

2019 ◽

Vol 16 (5) ◽

pp. 685 ◽

Cited By ~ 10

Author(s):

Mohanad Kamaz ◽

Arijit Sengupta ◽

Ashley Gutierrez ◽

Yu-Hsuan Chiao ◽

Ranil Wickramasinghe

Keyword(s):

Surface Modification ◽

Surface Properties ◽

Direct Contact ◽

Produced Water ◽

Surface Oxidation ◽

Membrane Distillation ◽

Mineral Salts ◽

Microscopy Imaging ◽

Pvdf Membrane ◽

Direct Contact Membrane Distillation

Direct contact membrane distillation (DCMD) has been conducted to treat hydraulic fracturing-produced water using polyvinylidenedifluoride (PVDF) membranes. Tailoring the surface properties of the membrane is critical in order to reduce the rate of adsorption of dissolved organic species as well as mineral salts. The PVDF membranes have been modified by grafting zwitterion and polyionic liquid-based polymer chains. In addition, surface oxidation of the PVDF membrane has been conducted using KMnO4 and NaOH. Surface modification conditions were chosen in order to minimize the decrease in contact angle. Thus, the membranes remain hydrophobic, essential for suppression of wetting. DCMD was conducted using the base PVDF membrane as well as modified membranes. In addition, DCMD was conducted on the base membrane using produced water (PW) that was pretreated by electrocoagulation to remove dissolved organic compounds. After DCMD all membranes were analyzed by scanning electron microscopy imaging as well as Energy-Dispersive X-Ray spectroscopy. Surface modification led to a greater volume of PW being treated by the membrane prior to drastic flux decline. The results indicate that tailoring the surface properties of the membrane enhances fouling resistance and could reduce pretreatment requirements.

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Membrane distillation crystallization using PVDF membrane incorporated with TiO2 nanoparticles and nanocellulose

Water Science & Technology Water Supply ◽

10.2166/ws.2020.068 ◽

2020 ◽

Vol 20 (5) ◽

pp. 1629-1642 ◽

Cited By ~ 1

Author(s):

Hoi-Fang Tan ◽

Why-Ling Tan ◽

N. Hamzah ◽

M. H. K. Ng ◽

B. S. Ooi ◽

...

Keyword(s):

Pore Size ◽

Tio2 Nanoparticles ◽

Polyvinylidene Fluoride ◽

Phase Inversion ◽

Membrane Distillation ◽

Coagulation Bath ◽

Membrane Thickness ◽

Permeate Flux ◽

Sem Images ◽

Pvdf Membrane

Abstract Polyvinylidene fluoride (PVDF) membrane was improved using TiO2 nanoparticles and nanocellulose for membrane distillation crystallization in this work. Besides the addition of TiO2 nanoparticles and nanocellulose, PVDF membrane was post-modified with octadecyltrichlorosilane after phase inversion using a dual coagulation bath. The addition of hydrophilic TiO2 nanoparticles and nanocellulose reduced membrane hydrophobicity, but the dispersed TiO2 nanoparticles assisted silane modification to improve surface hydrophobicity. Besides reducing the agglomeration of TiO2 nanoparticles, nanocellulose induced the formation of larger pore size and higher porosity as proven in SEM images and gravimetric measurement, respectively. The abundant moieties of nanocellulose accelerated the exchange between solvent and non-solvent during phase inversion for the formation of large pore size and porosity, but membrane thickness increased due to the thickening effects. The modified membrane showed higher water permeate flux in membrane distillation with salt rejection greater than 97%. Severe fouling in membrane distillation crystallization was not observed.

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