Azo Dye Functionalization of Polycarbonate Membranes for Water Purification*

With only 0.3% of fresh water being accessible on the surface of the Earth, having access to fresh water is a problem of global significance. Molecular dyes are used heavily in the World's growing textile industry, which contributes to roughly one-fifth of the industrial water pollution. In aqueous solutions, azo dye compounds dissociate into positive sodium ions and a negatively charged dye molecule. The research presented illustrates that polycarbonate filtration membranes with 100 nanometer diameter holes functionalized with azo dye molecules can successfully remove the negatively charged azo dye components from water. Rejection measurements are made using Ultra Violet Visible light Spectroscopy on the pre and post filtered solution. The rejection and flowrate response of filters using 3 different azo dyes separately will be presented. Using an azo dye with an intrinsic charge of -6 to functionalize a polycarbonate filter has been shown to increase rejection for the same dye by ~70% at a concentration of 50 µM.