Improved permeate flux and rejection of ultrafiltration membranes prepared from polyethylene terephthalate (PET) bottle waste

Abstract

The vast amount of not-recycled polyethylene terephthalate (PET) bottle waste is a serious threat to the environment. In order to utilize the waste, PET ultrafiltration membranes were prepared using PET bottle waste as the raw material by using the phase inversion technique. Low molecular weight polyethylene glycol (PEG 400) was used as the additive for the membranes. PET resin was also used as the membrane material to compare the properties of the membrane from PET bottle waste and those from the PET resin. The membrane prepared from PET bottle waste and that prepared from PET resin showed similar membrane characteristics such as IR spectra, morphology, hydrophilicity and porosity, indicating that instead of using PET resin, PET bottle waste can be utilized as a source of the polymer material to fabricate low-cost membranes. The morphology, hydrophilicity and porosity of the membranes were strongly affected by the PEG 400 concentration. The analysis of the membrane morphology using Scanning Electron Microscopy showed that the membranes had an asymmetric structure that consisted of a macroporous cross section and a smooth active layer. Increasing the PEG 400 concentration resulted in a smaller pore size, however the hydrophilicity and the porosity of the membranes increased. As a result, the membranes showed an increase in both permeate flux and rejection with increasing concentration of PEG 400 as observed from the results of the ultrafiltration experiments. Using Bovine Serum Albumin as a solute model in the feed, high values of rejection of up to 94% were achieved. Thus, ultrafiltration membranes with improved permeate flux and rejection could be prepared from PET bottle waste by the addition of PEG 400 as the additive.