Effect of Additive on Microstructure, Hydrophilicity and Ultrafiltration Performance of Polyethylene Terephthalate Membranes

Ultrafiltration is a pressure-driven separation process through a porous membrane that can separate particles or macromolecules from a solution. Ultrafiltration is mostly applied for water treatment processes in various industries such as pharmaceutical, chemical, food and beverage industries. Commercial ultrafiltration membranes are mostly fabricated from polymer materials such as polysulfone, polyethersulfone and cellulose acetate. These polymers are expensive, and for the time being they are not produced in Indonesia. In this work, polyethylene terephthalate (PET) bottle waste was used as the polymer material to prepare ultrafiltration membranes. PET is commonly used as a packaging material for foods and beverages due to its low price and excellent mechanical properties. The PET membranes were prepared via a phase-inversion technique using polyethylene glycol (PEG) as the additive. It was observed that the addition of PEG improved the flexibility and the hydrophilicity of the membranes. The water contact angle decreased to 61.5° by the addition of PEG. The microstructures of the membranes could be controlled by the molecular weight of the PEG. The result of the ultrafiltration experiment showed that the membrane with a high porosity, a large pore size and a high hydrophilicity exhibited a high water permeate flux. In the ultrafiltration experiment using a model feed solution of an aqueous solution containing Bovine Serum Albumin with a molecular weight of 66,000 Da, the membranes showed high rejection values of up to 90% with water permeate fluxes of 14.7 - 23.0 kg/(m²h). (paper)