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Poly (vinylidene fluoride-co-hexafluoropropylene) hollow fibre membrane for membrane distillation

Rashid, Khalid Turki (2017) Poly (vinylidene fluoride-co-hexafluoropropylene) hollow fibre membrane for membrane distillation. PhD thesis, Universiti Malaysia Pahang.

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Abstract

The poly (vinylidene fluoride-co-hexafluoropropylene), PVDF-co-HFP, hollow fibre membrane was successfully fabricated through an adoption in the phase inversion method. Polyvinylpyrrolidone (PVP) (MW, K-30) was utilized as a pore-forming additive to improve the morphology, structure and also characteristics of the PVDF-co-HFP membrane. Dimethylacetamide (DMAc) was used as solvent. Effects of the PVP concentration in dope solution on membrane structure were studied to obtain a membrane with good characteristics and be appropriate for Direct Contact Membrane Distillation (DCMD) applications. The impact of the concentration of aqueous NaCl solution, feed flow rate, and feed temperature on PVDFco-HFP hollow fibre permeation flux was evaluated. Morphological properties of all fibres were studied via field emission scanning electron microscopy (FESEM) and also atomic force microscopy (AFM). The formation of microvoids in the PVDF-co-HFP membrane was observed and the contact angle was slightly declined with an increase of PVP from (0 wt. % to 9 wt. %). Pore size of the hollow fibre increased significantly from 0.097 Jlm to 0.286 Jlm with the addition of PVP (0 to 9) wt. %. PVP in the dope solution, resulting in a remarkable increase in the water permeation flux from 4.2 to 22 kg/m2h at feed temperature of 80 °C. Also, the salt rejection for all hollow fibres was as high as 99.98%. It was also discovered that there was an increase in the permeate flux from 14 to 22 kg/m2h at feed temperature of 80°C by increasing the feed flow rate from 0.3 to 0.6 L/min, whereas an increment in the NaCl concentration in the feed stream from 3.5 to 5 wt.% led to a decline in the membrane permeate flux from 22 to 14.7 kg/m2h of membrane with 9 wt.% PVP. The success of formic acid modification onto PVDFco-HFP membrane with 5 wt.% PVP was proven by contact angle which increased from 97.8° to 109§, liquid entry pressure ofwater increased from 2 to 2.4 bar. Best permeate flux of the modified membrane with 9 wt. % PVP was about 23.9 kg/m2 h at 80°C feed temperature of sea water feed. The optimisation of the operating parameters of PVDF-co-HFP hollow fibre membrane for DCMD system was studied. The influence of the operation parameters, such as the feed temperature ( 40-80) °C, the feed flow rate (0.3-0.6 L/min), as well as the feed concentration varied from 3.5 wt. % to 5.0 wt. %, and their interactions on the PVDF-co-HFP membrane flux were investigated. The optimum operating parameters have been specified using Full Factorial and Taguchi optimization technique in order to obtain a good value of permeate flux. The results showed that PVDF-co-HFP membrane has best performance of20.4 (kg/m2 h) with the hot feed temperature of 78.8 °C, 0.6 L/min feed flow rate and 3.5 wt.% NaCl feed concentration. The predicted results by the developed model show a good agreement with the experimental data with a 6.95% error.

Item Type: Thesis (PhD)
Additional Information: Thesis (Doctor of Philosophy in Chemical Engineering) -- Universiti Malaysia Pahang – 2017, SV: DR. SUNARTI BINTI ABDUL RAHMAN, NO. CD: 11516
Uncontrolled Keywords: Polyvinylpyrrolidone; hollow fibre membrane
Subjects: Q Science > QD Chemistry
T Technology > TP Chemical technology
Faculty/Division: Faculty of Chemical & Natural Resources Engineering
Depositing User: Mrs. Sufarini Mohd Sudin
Date Deposited: 04 Jul 2019 06:24
Last Modified: 04 Jul 2019 06:24
URI: http://umpir.ump.edu.my/id/eprint/25223
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