Metal nanoparticle modified polysulfone membrane for water treatment
Membrane separation processes have been widely applied in the treatment of wastewater with polysulfone (PSF) polymer membrane being the most frequently used in ultrafiltration of wastewater due to its chemical and structural stability and mechanical robustness. The disadvantage to these membranes is their hydrophobicity which leads to membrane fouling caused by organic pollutants in water. Many studies have been conducted to increase the hydrophilic properties of the polysulfone membrane surface. Most recently metal oxide nanoparticles have been introduced to the polymer matrix in order to reduce membrane fouling and increase its hydrophilicity with measurable success. Natural organic matters are the one of the major fouling agents during ultrafiltration, reverse osmosis and microfiltration. Two organic acids (Tannic Acid and Alginic Acid) were selected to test the fouling behaviour of nanometallic synthesised polysulfone membranes. For this study, polysulfone casting suspension was prepared by dissolving polysulfone beads in N,N-dimethly acetamide. Three metallic nanoparticles of Silver, Cobalt and Nickel were selected to improve the hydrophilicity of the polysulfone membrane. The metal nanoparticles were prepared using the chemical reduction method. Cobalt nanoparticles were synthesized by dissolving the cobalt chloride salt in deionized water and reduced with sodium borohydride at room temperature. The nickel chloride salt was dissolved in ethanol and reduced with sodium borohydride under magnetic stirrer. Silver nanoparticles were prepared by dissolving the silver nitrate in deionised water and heated to boil, the sodium citrate was added to reduced the silver nitrate. These nanoparticles were then integrated into the polysulfone polymer matrix to form the metal nanoparticle polysulfone nanocomposites. This study focused on four prepared polysulfone nanocomposite membrane; 1 unmodified polysulfone (PSF), 2 polysulfone modified with cobalt nanoparticles (PSF/Co), 3 polysulfone modified with nickel nanoparticles (PSF/Ni) and 4 polysulfone modified with silver nanoparticles (PSF/Ag).