Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation

Membrane distillation (MD) is a technology that makes use of the temperature difference created across the membrane. One of the main challenges in MD research is to fabricate membranes with high wetting resistance and high permeate flux. To date, very limited work has reported on the use of both hyd...

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Main Author:	Ravi, Jeganes
Format:	Thesis
Language:	English
Published:	2021
Subjects:	Q Science (General) TP Chemical technology
Online Access:	http://eprints.utm.my/id/eprint/101510/1/JeganesRaviMSChE2021.pdf
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spelling	my-utm-ep.1015102023-06-26T02:00:32Z Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation 2021 Ravi, Jeganes Q Science (General) TP Chemical technology Membrane distillation (MD) is a technology that makes use of the temperature difference created across the membrane. One of the main challenges in MD research is to fabricate membranes with high wetting resistance and high permeate flux. To date, very limited work has reported on the use of both hydrophobised carbon-based nanoparticles and hydrophobicity gradient in achieving those qualities. Thus, this work was focused on the fabrication of dual-layer hollow fibre polyvinylidene fluoridebased nanaocomposite membranes with hydrophobic gradient. The nanocomposite membranes were incorporated with hydrophobised nanoparticles, i.e. multi-walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP). The effect of different concentrations of nanoparticles (1 and 2 wt%) on the performance of the membranes was investigated as well. The nanoparticles were oxidised with concentrated nitric acid and sulphuric acid, hydrophobised with 1H,1H,2H,2H-perfluorodecyltriethoxysilane and characterised to confirm the hydrophobisation and determine their specific surface area. The hydrophobicity gradient was created by introducing the hydrophobised nanoparticles in the outer layer dope solution and hydrophilic polyethylene glycol in the inner layer dope solution. The dual-layer membranes were then fabricated and characterised to determine their wetting resistance, chemical composition, surface and cross-sectional morphology, pore size, porosity and contact angle before their performances were tested in a direct contact membrane distillation (DCMD) set-up. MWCNT and GNP were successfully oxidised and hydrophobised as confirmed by energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) results. Both the hydrophobised nanoparticles had smaller Brunauer-Emmett-Teller (BET) specific surface area as compared to the pristine nanoparticles. All the fabricated membranes had an asymmetrical structure with finger-like and sponge-like pores in the inner and outer layers respectively. The outer layers of the nanocomposites membranes were hydrophobic and the membrane with 2 wt% of hydrophobised GNP had the highest contact angle of 111.1°. All the inner layers of the membranes were found to be hydrophilic, thus proving that hydrophobicity gradients were achieved in the membranes. The surface roughness, contact angle and wetting resistance of all the nanocomposite membranes were higher than the neat membrane and the values increased with increasing concentration of nanoparticles. Membranes incorporated with GNP showed better performance in terms of contact angle and wetting resistance. All the nanocomposite membranes showed better DCMD performance than the neat membrane. The membrane incorporated with 2 wt% of hyrophobised GNP achieved the highest flux of 8.27 kg/(m2h) at feed temperature of 80?. All the membranes achieved a salt rejection of more than 99%. Nonetheless, the flux of the membranes were quite low compared to the flux of membranes reported in the literature, likely due to small pore sizes and dense interfaces. 2021 Thesis http://eprints.utm.my/id/eprint/101510/ http://eprints.utm.my/id/eprint/101510/1/JeganesRaviMSChE2021.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:145641 masters Universiti Teknologi Malaysia, Faculty of Engineering - School of Chemical & Energy Engineering Faculty of Engineering - School of Chemical & Energy Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	Q Science (General) TP Chemical technology
spellingShingle	Q Science (General) TP Chemical technology Ravi, Jeganes Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
description	Membrane distillation (MD) is a technology that makes use of the temperature difference created across the membrane. One of the main challenges in MD research is to fabricate membranes with high wetting resistance and high permeate flux. To date, very limited work has reported on the use of both hydrophobised carbon-based nanoparticles and hydrophobicity gradient in achieving those qualities. Thus, this work was focused on the fabrication of dual-layer hollow fibre polyvinylidene fluoridebased nanaocomposite membranes with hydrophobic gradient. The nanocomposite membranes were incorporated with hydrophobised nanoparticles, i.e. multi-walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP). The effect of different concentrations of nanoparticles (1 and 2 wt%) on the performance of the membranes was investigated as well. The nanoparticles were oxidised with concentrated nitric acid and sulphuric acid, hydrophobised with 1H,1H,2H,2H-perfluorodecyltriethoxysilane and characterised to confirm the hydrophobisation and determine their specific surface area. The hydrophobicity gradient was created by introducing the hydrophobised nanoparticles in the outer layer dope solution and hydrophilic polyethylene glycol in the inner layer dope solution. The dual-layer membranes were then fabricated and characterised to determine their wetting resistance, chemical composition, surface and cross-sectional morphology, pore size, porosity and contact angle before their performances were tested in a direct contact membrane distillation (DCMD) set-up. MWCNT and GNP were successfully oxidised and hydrophobised as confirmed by energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) results. Both the hydrophobised nanoparticles had smaller Brunauer-Emmett-Teller (BET) specific surface area as compared to the pristine nanoparticles. All the fabricated membranes had an asymmetrical structure with finger-like and sponge-like pores in the inner and outer layers respectively. The outer layers of the nanocomposites membranes were hydrophobic and the membrane with 2 wt% of hydrophobised GNP had the highest contact angle of 111.1°. All the inner layers of the membranes were found to be hydrophilic, thus proving that hydrophobicity gradients were achieved in the membranes. The surface roughness, contact angle and wetting resistance of all the nanocomposite membranes were higher than the neat membrane and the values increased with increasing concentration of nanoparticles. Membranes incorporated with GNP showed better performance in terms of contact angle and wetting resistance. All the nanocomposite membranes showed better DCMD performance than the neat membrane. The membrane incorporated with 2 wt% of hyrophobised GNP achieved the highest flux of 8.27 kg/(m2h) at feed temperature of 80?. All the membranes achieved a salt rejection of more than 99%. Nonetheless, the flux of the membranes were quite low compared to the flux of membranes reported in the literature, likely due to small pore sizes and dense interfaces.
format	Thesis
qualification_level	Master's degree
author	Ravi, Jeganes
author_facet	Ravi, Jeganes
author_sort	Ravi, Jeganes
title	Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
title_short	Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
title_full	Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
title_fullStr	Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
title_full_unstemmed	Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
title_sort	polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation
granting_institution	Universiti Teknologi Malaysia, Faculty of Engineering - School of Chemical & Energy Engineering
granting_department	Faculty of Engineering - School of Chemical & Energy Engineering
publishDate	2021
url	http://eprints.utm.my/id/eprint/101510/1/JeganesRaviMSChE2021.pdf
_version_	1776100715152801792

Polyvinylidene fluoride-based dual-layer hollow fibre nanocomposite membranes for membrane distillation

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