The photocatalytic degradation of Rhodamine B(RhB) was carried out using TiO2 supported on activated carbon(TiO2-AC) under microwave irradiation.Composite catalyst TiO2-AC was prepared and characterized using X-ray diffraction(XRD),transmission electron microscopy(TEM) and Brunauer-Emmett-Teller(BET).In the process of microwave-enhanced photocatalysis(MPC),RhB(30 mg/L) was almost completely decoloured in 10 min,and the mineralization effciency was 96.0% in 20 min.The reaction rate constant of RhB in MPC using TiO2-AC by pseudo first-order reaction kinetics was 4.16 times of that using Degussa P25.Additionally,according to gas chromatography/mass spectrometry(GC/MS) and liquid chromatography/mass spectrometry(LC/MS) identification,the major intermediates of RhB in MPC included two kinds of N-de-ethylation intermediates(N,N-diethyl-N'-ethyl-rhodamine(DER)),oxalic acid,malonic acid,succinic acid,and phthalic acid,maleic acid,3-nitrobenzoic acid,and so on.The degradation of RhB in MPC was mainly attributed to the destruction of the conjugated structure,and then the intermediates transformed to acid molecules which were mineralized to water and carbon dioxide.
HE Zhong,YANG Shaogui,JU Yongming,SUN Cheng State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing 210093,China.
A solution of atrazine in a TiO_(2)suspension,an endocrine disruptor in natural water,was tentatively treated by microwave-assisted photocatalytic technique.The effects of mannitol,oxygen,humic acid,and hydrogen dioxide on the photodegradation rate were explored.The results could be deduced as follows:the photocatalytic degradation of atrazine fits the pseudo-first-order kinetic well with k=0.0328 s–1,and·OH was identified as the dominant reactant.Photodegradation of atrazine was hindered in the presence of humic acid,and the retardation effect increased as the concentration of humic acid increased.H_(2)O_(2)displayed a significant negative influence on atrazine photocatalysis efficiency.Based on intermediates identified with gas chromatography-mass spectrometry(GC-MS)and Liquid chromatography-mass spectrometry(LC-MS/MS)techniques,the main degradation routes of atrazine are proposed.
