A novel low-energy hybrid process for the removal of organic contaminants in ultrapure water systems

To achieve the goal of implementation of low-energy and low-chemical usage for trace organic compound removal, the hybrid oxidation/adsorption purification system using nitrogen-doped titanium dioxide catalytic oxidation followed by activated carbon adsorption was proposed in this paper. When isopropyl alcohol, ethylene glycol, and urea were selected as model components, superior oxidation effects were achieved by combination of nitrogen-doped titanium dioxide with 254nm UV unit than by traditional high-energy-consumed 185nm UV unit, which indicated such configuration would be an ideal candidate to replace the current high-energy-consumed UV unit. By incorporating this new configuration into the semiconductor wastewater recycling system, the granule-activated carbon bed adsorption efficiency for total organic carbon was compared with the granule-activated carbon adsorption efficiency for total organic carbon in traditional purification system, where the 185nm UV lamp was used as oxidation unit. The experimental results showed that the hybrid low energy consumption catalytic oxidation/adsorption system had higher efficiency than the traditional high-energy-consumed oxidation/adsorption system for trace organic compound removal. This was because the radicals formed in the UV oxidation process reacted with the organic compounds adsorbed on the activated carbon and regenerated the adsorption sites. This self-cleaning mechanism effectively extended the lifetime of activated carbon bed and increased its adsorption capability. (c) 2013 Curtin University of Technology and John Wiley & Sons, Ltd.