Ultrafiltration Membranes Modified by Plasma and its Application in the Viral Removal in Water Treatment

MERCEDES L. MÉNDEZ; VERÓNICA B. RAJAL; ELZA CASTRO VIDAURRE

Río de Janeiro

Simposio; II Simposio de Processos de Separacao com Membranas; 2013

Currently the plasma treatment is a tool widely used in surface modification of different materials to optimize their properties in order to a particular application. In the present work, low temperature plasma technique was used to modify ultrafiltration (UF) membranes using an inductive reactor. The aim was enhance hydrophilicity and uniform surface pores of the UF membranes leading to less fouling and subsequent flux enhancement. The UF membranes were of Polyethersulfone (PES) and synthesized for the phase inversion method. Additionally, polyethylene glycol (PEG) of molecular weight 10.000 was used as additive, dimethylacetamide (DMAc) and water as solvent and the non-solvente, respectively. The modification was made in two consecutive treatments, first with argon plasma (Ar) followed by polymerization with acrylic acid (AA). The pre-treatment with Ar plasma was performed for 2, 5, 10 and 15 minutes at a pressure of 200 mTorr, with the goals of cleaning the surface and improve adhesion between the substrate and plasma polymerised acrylic acid coatings. In the plasma polymerization was used a mixture of AA with Ar at a pressure of 300 mTorr by 30 minutes. The radio frequency power source (8- 13.56 kHz) was 10,2W for all case. The characterization of the membranes before and after the surface modification was done using contact angle to determine its effect on the surface hydrophilicity. Also SEM and AFM images have been used to know the membrane morphology and Liquid-liquid Displacement Porosimetry (LLDP) was used to quantify the pore size distributions. The pure water permeability and tests of retention of viral model, bacteriophage PP7 using the host Pseudomonas aeruginosa, were measured showing a proper performance. Finally, the fouling was evaluated by measuring the relative water reduction (RFR). As of analysis of the properties of the modified membranes the changes observed on the surface of these were reduction and uniformity of the surface pores and increase hydrophilicity, and in terms of performance of ultrafiltration membranes were observed increasing its permeability and smaller RFR values after filtration with PP7, with respect to unmodified membranes.