Preparation of poly(m‐phenylenediamine)/ZnO composites and their photocatalytic activities for degradation of C.I. acid red 249 under UV and visible light irradiations

Abstract

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·) were the main oxidants in the photodegradation reactions. However, in the visible light/PMPD/ZnO system, the main oxidant was hydroxyl radicals (OH·). © 2013 American Institute of Chemical Engineers Environ Prog, 33: 123–130, 2014