Effects of titanate nanotubes synthesized by a microwave hydrothermal method on photocatalytic decomposition of perfluorooctanoic acid.

Titanate nanotubes (TNTs) were used to remove perfluorooctanoic acid (PFOA) from aqueous solutions in this study. Direct photolysis of PFOA by a 254-nm UV light (400 W) was found effective to decompose PFOA without presence of photocatalysts. Shorter-chain perfluorocarboxylic acids (PFCAs) and fluoride ions were formed during photodecomposition. Addition of TNTs as photocatalysts did not greatly enhance photocatalytic decomposition of PFOA. TNTs mainly act as adsorbents to adsorb PFOA and form TNT-PFOA complexes. It suggested that sodium ions and oxygen atoms on the surfaces of TNTs play important roles in PFOA adsorption. X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) analyses indicated that ion-exchange, electrostatic interaction, and hydrophobic interaction all participated in the photocatalytic reaction of PFOA by TNTs. Crown