Clean drinking water is vital to safeguard the public health. Industrialization and population growth have resulted in the pollution of natural water resources, which have posed tremendous stress on the drinking water supply. Typical drinking water contaminants include metal or metalloids as hexavalent chromium Cr(VI), selenite Se(VI) and arsenate As(V) disinfection byproducts. The high solubility and mobility of these compounds pose challenges to designing efficient and cost effective treatment processes. This study is aimed to develop an efficient reductive treatment process to remove a series of drinking water contaminants using nano-catalyst of TiO2. Conventional TiO2 has been used as a photocatalyst for oxidative water treatment by generating hydroxyl radical (HO). However, it is not an effective catalyst for reductive reaction due to poor electron-hole separation under UV irradiation. In this study, new types of low-cost TiO2 nanoparticles are synthesized by doping with trace barium (Ba) to its lattice structure. Barium’s effect on the photocatalytic activity of TiO2 is due to the dynamics of electron-hole recombination and interfacial charge transfer. The barium ions can serve as both hole and electron traps or they can mediate interfacial charge transfer. Using Cr (VI) as a model drinking water contaminant, 10 mg/L Cr(VI) was reduced by 99% in 10 seconds with 50 mg/L Barium doped TiO2 concentration at pH 7.45, whereas standard TiO2 only catalyzed 60% of Cr(VI) degradation. The Ba-doped TiO2 from these studies was shown to be a much more effective photocatalyst than the P25 TiO2 (Degussa) towards Cr(VI) reduction. Confirmation of Cr(VI) reduction was confirmed by visual observation of formation of Cr(III) particles. Future plans are to investigate the impacts of typical chemical water parameters such as pH, alkalinity and natural organic matter, on the efficiency of TiO2 in reducing Cr(VI).

Photocatalytic reductive treatment of hexavalent chromium using barium doped TiO2

249th National Meeting (2015)

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