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تحضير غشاء ال PVC لتقطير الفراغي بالاغشية والترشيح الدقيق جدا عن طريق التطعيم مع PEA وPVP كمضافات == Preparation of PVC membrane for Vacuum membrane distillation and nanofiltration by grafting with PEA and PVP as additives
Author name:
منال افهم توما الصائغ
Supervisor name:
طارق سهيل نجم | قصي فاضل الصالحي
General topic:
Chemistry
Specific topic:
Chemistry
Degree:
Doctorate
University:
Mustansiriyah University - College Of Science
Language:
English
University location:
Baghdad
First pages:
25T1851 - p.pdf
Abstract:
The present work divided in to two parts, in the first part; hydrophobic modification of polyvinyl chloride (PVC) was performed with the introduction of ethyl acrylate (EA) monomer onto the polymer backbone by free radical graft copolymerization with Benzoylperoxid as initiator. The effect of grafted copolymerization reaction time (1.5 - 4.5h), and monomer concentration (0.3 - 1.3M) on polymerization yield was evaluated. Mechanism described the free radical graft copolymerization was proposed. Membranes from PVC and grafted PVC solutions were prepared via immersion precipitation process for vacuum membrane distillation (VMD) application. The success of EA grafting onto PVC was confirmed by Fourier - transform infrared (FTIR) spectroscopy, and energy - dispersive X - ray spectroscopy (EDX). The membranes were characterized by scanning electron microscopy (SEM) analysis, and measurements of contact angle, thickness, pore size, and porosity. Fourier - transform infrared (FTIR) data showed that the PVC - g - PEA displayed new absorption peaks indicated the introduction of the EA ester group on PVC. A significant difference between the spectrum of the PVC and PVC - g - PEA in the peak of chlorine and carbon was observed by using EDX analysis. The EA grafting onto PVC could affect the structural morphology of the PVC - g - PEA membranes by increasing percentage of porosity and the largest pore size, the contact angle of the prepared membranes, and also by reducing membrane thickness. According to the results of VMD on distilled water, the permeate flux of the modified membrane was improved by about 15 times compared to the unmodified PVC membrane. The highest permeate flux of theAbstractmodified membrane was about 41 kg/m2h at 60°C of feed temperature and 2 mbar of vacuum pressure. In the second part; hydrophilic physically modified polyvinyl chloride (PVC) was established by blending of polyvinyl chloride (PVC) and polyvinyl pyrrolidone (PVP). The Nanofiltration flat sheet membranes prepared from different concentrations of PVC (i.e., 18, 20, 22 and 24 wt.%) with 3wt.% PVP - 90k as a polymer additive via immersion precipitation method was carried out. The resulted membranes were characterized by scanning electron microscope (SEM) observations, atomic force microscopy (AFM), Fourier - Transform infrared (FTIR) spectroscopy, thickness, contact angle measurement, mechanical test, pore size and porosity. Nanofiltration process is applied to evaluate the performance of the membranes with distilled water and 0.6M NaCl solution at different; pressure (10 - 18 bar), flow rate (150 - 450 l/min) and feed temperature (25 - 35oC). The results showed that with increasing of PVC concentration in present of 3% PVP additive increases the Young’s Modulus from 147.87 MPa to 242.13 MPa, strength at Break from 5.06MPa to 7.37 MPa, Elongation at break from 26.24% to 54.95 % and hydrophilicity from 83.0% to 60.0 % while decreased porosity from 82.85% to73.04%, Equilibrium Water Content (EWC) from 85.0% to 63.5%andpore size from 0.13μm to 0.07 μm. The water flux increased when increasing flow rate, pressure and temperature but decreased with increasing PVC concentration while the NaCl rejection decreased with increasing pressure, temperature and PVC concentration.
