One-Step Fabrication of Photocatalytic Nanoporous Titania for Efficient Water Treatment

Master of Science, Graduate Program in Mechanical Engineering
University of California, Riverside, June 2015
Dr. Masaru Rao, Chairperson

Titanium  dioxide has  been shown  to  degrade  organic  contaminants  in  water through  photocatalysis.  While  current  research  focuses  on  maximizing degradation  efficiency,  a  need  exists  to  further  investigate  the  oxidation properties of  titania as  a  means  to  tailor  this  material  for  integration into  a high-throughput  device.  Herein  we  present  a  nanoporous  titania  (NPT) exhibiting good degradation efficiency as groundwork for a microfluidic reactor. Using hydrogen peroxide (H2O2) oxidation of titanium substrates, we were able to grow a high surface area nanoporous film with good structural integrity, and little to no signs of delamination. A growth parameter study was conducted to determine  the  optimal  oxidation  conditions  for  photocatalytic  activity. Characterization of the material was carried out with XRD and SEM to record the effects of H2O2 concentration, temperature, and time on the morphology and crystallinity of the NPT. In order to establish a standard, we used BET analysis to calculate a surface area of Degussa P25 comparable to our NPT 1x1 in2 chip. Photocatalytic response was measured and compared to P25 drop-casted films via degradation of methylene blue. Over the course of three hours, we observed a 56.13% and a 76.16% degradation of methylene blue from our NPT and P25 samples, respectively. The degradation of methylene blue was found to be a first order reaction with the two materials demonstrating reaction rate constants of 0.0045 (NPT) and 0.0081 (P25) mg/L min-1. The studies conducted show that NPT  is  an  efficient  photocatalyst  with  good  structural  integrity  to  suit applications in microfluidic reactors.