Photodecolorization of methyl orange over 伪-Fe₂O₃-supported HY catalysts: The effects of catalyst preparation and dealumination

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• 作者：Nur Farhana Jaafar^a ; Aishah Abdul Jalil^b ; ^{aishah@cheme.utm.my} ; ^{aishah.aj@gmail.com} ; Sugeng Triwahyono^a ; Muhd Nazlan Muhd Muhid^c ; Norzahir Sapawe^b ; Mohammad Azrul Hisham Satar^b ; Hanak Asaari^b
• 关键词：伪-Fe2O3/HY catalyst ; Electrochemical ; Dealumination ; Photodecolorization ; Methyl orange
• 刊名：Chemical Engineering Journal
• 出版年：2012
• 期刊代码：16_13858947
• 类别：ce
• 出版时间：15 May, 2012
• 卷：191
• 期：Complete
• 页码：112-122
• 文件大小：1860 K

摘要

An 伪-Fe₂O₃-supported HY zeolite (伪-Fe₂O₃/HY) was prepared by introducing nanosized 伪-Fe₂O₃ into an HY zeolite support through in situ (伪-Fe₂O₃/HY_IS) and ion-exchange (伪-Fe₂O₃/HY_IE) methods. The effect of the preparation methods on the physicochemical properties of the catalyst were studied via XRD, FESEM-EDX, TEM, UV-vis DRS, FTIR, XPS, ²⁹Si and ²⁷Al MAS NMR, ESR and BET surface area analysis. In this study, dealumination was accomplished by using a facile electrolysis system without any strong acids, reactive compounds and/or hydrothermal treatment. Dealumination accompanied by ion exchange of Al with Fe³⁺ ions in the HY zeolite framework resulted in the formation of an active species that had a higher photoactivity towards the decolorization of methyl orange (MO). A 5 wt%伪-Fe₂O₃/HY_IS was found to produce an 80%photodecolorization of 30 mg L^鈭? of MO at pH 2 with 0.375 g L^鈭? catalyst, while 5 wt%伪-Fe₂O₃/HY_IE only produced 23%photodecolorization under similar conditions (2 h reaction time). This study showed that the kinetics follow a pseudo-first order Langmuir-Hinshelwood model with an activation energy (E_a) calculated for both 5 wt%伪-Fe₂O₃/HY_IS and 5 wt%伪-Fe₂O₃/HY_IE to be 45.8 kJ mol^鈭? and 70.2 kJ mol^鈭?, respectively. Measurements of the mineralization of MO by COD, BOD₅ and TOC analysis were 27.0%, 69.6%and 16.9%, respectively, after 2 h of contact time. The Fe dissolution from the catalyst showed insignificant leaching of Fe (<1%) when subjected to AAS. A reusability study demonstrated that 伪-Fe₂O₃/HY_IS could be a promising photocatalyst for the degradation of various dyes in wastewater.