Preparation, characterization, and application of TiO 2 -patterned polyimide film as a photocatalyst for oxidation of organic contaminants.

Photocatalytically active TiO ₂ -patterned polyimide (PI) films (PI-TiO ₂ ) were fabricated using thermal transfer patterning (TTP). When subjected to hot pressing, the TiO ₂ 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°C and 100MPa was optimum for obtaining patterns with uniform TiO ₂ coverage. When the quantity of TiO ₂ on the template increased, the amount of it immobilized on PI film also increased from 0.3245 to 1.2378mg per 25cm ² . XPS studies confirmed the presence TiO ₂ 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-TiO ₂ with 1.2378mg/25cm ² TiO ₂ loading exhibited the highest photocatalytic performance for methylene blue (10μM) degradation, with a rate constant of 0.0225min ^-1 and stable photocatalytic efficacy for 25 cycles of reuse. The PI-TiO ₂ 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 TiO ₂ photocatalyst.
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