Photodegradation of perfluorooctanoic acid by synthesized TiO2–MWCNT composites under 365 nm UV irradiation

Degradation of perfluorooctanoic acid (PFOA) is of great importance due to its global distribution, persistence and toxicity to bioorganisms. In present study, a composite TiO2 with multiple wall carbon nano-tubes (MWCNTs) was synthesized using sol–gel method and it was used as photocatalyst to degrade PFOA in water. The prepared composite catalyst displayed significant absorption in UV to visible light region. The loading content of TiO2 on MWCNTs could be adjusted by changing the ratio of precursor to MWCNTs. Due to the combined effect of the adsorption ability and e− transport capacity of MWCNT, the composites displayed much higher photocatalytic ability to PFOA as compared to pure TiO2 under UV irradiation. The photocatalyst prepared with 10:1 of tetrabutyl titanate/MWCNT was the most effective. With the optimal dosage at 1.6 g L−1, almost 100% of PFOA was degraded in acid medium after irradiation for 8 h. It was proposed that PFOA were mainly degraded by stepwise losing a moiety of CF2.

► TiO2–MWCNT composite displays high degradation efficiency to PFOA.
► Adsorption/e− transport ability of MWCNT enhances photocatalytic activity of TiO2.
► Acid medium favors the photocatalytic degradation of PFOA by the composites.
► PFOA degradation occurs by stepwise lose of a moiety of CF2 and hydrolysis.