Preparation, characterization, and application of TiO2-patterned polyimide film as a photocatalyst for oxidation of organic contaminants

Abstract

Photocatalytically active TiO2-patterned polyimide (PI) films (PI-TiO2) were fabricated using thermal transfer patterning (TTP). When subjected to hot pressing, the TiO2 nanoparticles electrosprayed on steel mesh templates were successfully transferred and formed checker plate patterns on PI film. FE-SEM studies confirmed that pressing at 350 degrees C and 100 MPa was optimum for obtaining patterns with uniform TiO2 coverage. When the quantity of TiO2 on the template increased, the amount of it immobilized on PI film also increased from 0.3245 to 1.2378 mg per 25 cm(2). XPS studies confirmed the presence TiO2 on the patterns, and indicated the formation of carboxylic acid and amide groups on the PI surface during TTP. When tested under UVA irradiation, PI-TiO2 with 1.2378 mg/25 cm(2) TiO2 loading exhibited the highest photocatalytic performance for methylene blue (10 mu M) degradation, with a rate constant of 0.0225 min(-1) and stable photocatalytic efficacy for 25 cycles of reuse. The PI-TiO2 was also successfully used to degrade amoxicillin, atrazine, and 4-chlorophenol. During photocatalysis, the toxicity of 4-chlorophenol against Vibrio fischeri and the antibiotic activity of amoxicillin against Escherichia coli were decreased. Overall, TTP was found to be a potentially scalable method for fabricating robust immobilized TiO2 photocatalyst.