Production of TiO2-deposited Diatoms and Their Applications for Photo-catalytic Degradation of Aqueous Pollutants

Abstract

Biogenic TiO2 diatoms can be prepared by metabolic incorporation of TiO2 on the frustule surface of the diatoms. To utilize the photo-catalytic activity of biogenic TiO2 for practical applications, high production of TiO2-deposited diatoms is required. Here, we evaluated the growth rate and biogenic TiO2 production of several domestic diatom species. Among the tested diatoms, Caloneis schroederi (CS) showed high biomass production (4.01 g/L) in a two-stage cultivation system and proper exoskeletal rigidity for efficient production of biogenic TiO2. The dry weight of the TiO2-deposited CS frustules (biogenic CS-TiO2) was 4.52 g/L. Biogenic CS-TiO2 showed significant photo-catalytic degradation of Congo Red in water with an efficiency of 27.8%, which is higher than that of standard TiO2 (17.4%). In addition, chloroform could be removed from water through the photo-catalytic activity of biogenic CS-TiO2 (91%). Therefore, the biogenic CS-TiO2 developed in this study can be employed for the treatment of pollutant-contaminated wastewater.