Preparation of Poly(m-phenylenediamine)/ZnO Composites and Their Photocatalytic Activities for Degradation of CI Acid Red 249 under UV and Visible Light Irradiations

Poly(m-phenylenediamine)/ZnO (PMPD/ZnO) composites were successfully synthesized by chemical oxidative polymerization method. Powder X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), transmission electron microscope, and UV-vis spectra (UV-vis) were used to characterize the prepared PMPD/ZnO composites. Their photocatalytic activities were evaluated by the degradation of C.I. Acid Red 249 (AR249) aqueous solutions under UV and visible light irradiations. Results showed that PMPD/ZnO composites exhibited good photocatalytic activities under UV and visible light irradiations, whereas neat ZnO had only ultraviolet light photocatalytic activity. Moreover, PMPD/ZnO composites had better photocatalytic stabilities. After five successive cycles, their photocatalytic activities for degradation of AR249 were still over 75% of that for the first cycling run under UV and visible light irradiations. The inhibition of AR249 degradation by adding isopropyl alcohol (IPA) and 1-butanol (1-BuOH) to the UV/PMPD/ZnO system revealed that both photogenerated holes (h(+)) and hydroxyl radicals (OH center dot) were the main oxidants in the photodegradation reactions. However, in the visible light/PMPD/ZnO system, the main oxidant was hydroxyl radicals (OH). (c) 2013 American Institute of Chemical Engineers Environ Prog, 33: 123-130, 2014