Microwave photocatalytic degradation of Rhodamine B using TiO2 supportedon activated carbon: Mechanism implication
HE Zhong , YANG Shaogui , JU Yongming , SUN Cheng
DOI:
Received February 17, 2008,Revised April 22, 2008, Accepted , Available online
Volume 21,2009,Pages 268-272
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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 di raction (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 e ciency 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.
