Anionic Azo Dye Functionalization of Polycarbonate Membranes for Water Purification*

The second most prominent polluter of freshwater, following the agriculture industry, is the textile industry. An estimated 2.8 x 10⁵ tons of synthetic textile dyes are discharged into the environment each year. One widely used dye type is the azo dye family. Recent research has shown that when filtering aqueous solutions of a specific anionic azo dye through a porous polycarbonate filter, at concentrations up to 1000 micromolar, the filters became functionalized. Such filters were then used to remove 96.4% of the textile dye from aqueous solutions at a lower concentration of 50 micromolar. This innovative method of azo-dye-functionalization demonstrates that the dyes themselves, while being problematic when discharged to the environment, have the potential to be part of the solution. Dye rejection results measured using ultraviolet visible light spectroscopy from this innovative functionalization process will be presented for 8 anionic azo dyes. The 50 micromolar aqueous solutions vary from 7.7 – 53.5 % when comparing their pre- and post-functionalization dye rejection. Much of the research presented is based on data acquired by a team of 3 National Science Foundation Research Experience for Undergraduate students.