Photoelectrocatalytic degradation of p-chloronitrobenzene by g-CN/TiO nanotube arrays photoelectrodes under visible light irradiation.

As a typical refractory pollutant, p-chloronitrobenzene (p-CNB) from industrial wastewater poses a serious threat to the aquatic environment safety and human health. The photoelectrocatalytic (PEC) technology is regarded as a promising and cleaner approach for p-CNB removal. Therefore, the graphitic carbon nitride (g-CN) modified TiO nanotube arrays (g-CN/TNAs) were prepared as the photoelectrodes for p-CNB degradation. The PEC degradation efficiency for p-CNB by g-CN/TNAs (0.00484 min) was much higher than that by bare TNAs (0.00135 min) under visible light. The g-CN/TNAs photoelectrodes exhibited excellent visible-light response, efficient charges separation and high redox potentials of electron/hole, which was favorable for p-CNB degradation. The radical scavenging experiments indicated that both reductive electrons and oxidized species (holes and ·OH) played crucial roles simultaneously during the dechlorination process, whereas the mineralization of p-CNB mainly depended on the photo-generated holes and ·OH. The degradation pathways of p-CNB were proposed through GC/MS spectra. The acute toxicity, bioaccumulation factor and mutagenicity of identified intermediates were reduced after PEC degradation by g-CN/TNAs photoelectrodes. The Z-scheme g-CN/TNAs provided an efficient approach for simultaneous dechlorination and mineralization of refractory pollutants.