Synthesis of iron-based metal-organic framework MIL-53 as an efficient catalyst to activate persulfate for the degradation of Orange G in aqueous solution

Mengjie Pu, Zeyu Guan, Yongwen Ma, Jinquan Wan, Yan Wang, Mark L Brusseau, Haiyuan Chi

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35 Scopus citations

Abstract

A series of MIL-53(Fe) materials was synthesized using a solvothermal method under different temperature and time conditions and were used as catalysts to activate persulfate and degrade Orange G (OG). Influences of the above conditions on the crystal structure and catalytic behavior were investigated. Degradation of OG under different conditions was evaluated, and the possible activation mechanism was speculated. The results indicate that high synthesis temperature (larger than 170 °C) leads to poor crystallinity and low catalytic activity, while MIL-53(Fe) cannot fully develop at low temperature (100 or 120 °C). The extension of synthesis time from 5 h to 3 d can increase the crystallinity of the samples, but weakened the catalytic activity, which was caused by the reduction of BET surface area and the amount of Fe (II)-coordinative unsaturated sites. Among all the samples, MIL-53(Fe)-A possesses the best crystal structure and catalytic activity. In optimal conditions, OG solution can be totally decolorized after degradation for 90 min, and a removal rate of 74% for COD was attained after 120 min. The initial solution pH had great influence on OG degradation, with the greatest removal in acidic pH environment. ESR spectra showed that sulfate radical (SO4 [rad]), hydroxyl radical (OH[rad]), persulfate radical (S2O8 [rad]), and superoxide radical (O2[rad]) exist in this system under acidic conditions. Furthermore, with the increase of pH, the relative amount of O2[rad] increases while that of OH[rad] and SO4 [rad] decreases, resulting in a reduced oxidizing capacity of the system.

Original languageEnglish (US)
Pages (from-to)82-92
Number of pages11
JournalApplied Catalysis A: General
Volume549
DOIs
StatePublished - Jan 5 2018

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Keywords

  • Catalytic activity
  • Chemical oxidation
  • Metal-organic frameworks
  • MIL-53(Fe)
  • Persulfate
  • Sulfate radical

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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