Modification of polyvinyl chloride (PVC) membrane for vacuum membrane distillation (VMD) application

Abstract

In the present work, 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. Membranes from polyvinyl chloride 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 contact angle, pore size and porosity measurements. FTIR data showed that the PEA-g-PVC displayed new absorption peaks, indicating the introduction of the EA ester group on PVC. A significant difference between the spectrum of the PVC and PEA-g-PVC 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, and increase the porosity, largest pore size and contact angle of the prepared membranes, whereas the membrane thickness is reduced. According to the results of VMD process on pure 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 the modified membrane was about 37.5kg/m2h at 60°C of feed temperature and 2mbar of vacuum pressure.