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

Abstract

A series of MIL-53(Fe) materials were 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 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−·), hydroxyl radical (OH·), persulfate radical (S2O8−·), and superoxide radical (O2·) exist in this system under acidic conditions. Furthermore, with the increase of pH, the relative amount of O2· increases while that of OH· and SO4−· decreases, resulting in a reduced oxidizing capacity of the system.

Effective Photocatalytic Activity of Mixed Ni/Fe-Base Metal-Organic Framework under a Compact Fluorescent Daylight Lamp

“…They can be explained by the effect of the synthesis temperature on the structure formation of MIL-53(Fe). Pu et al demonstrated that iron ion and H 2 BDC could not coordinate successfully under a low temperature (100 • C), and therefore the MIL-53(Fe) crystal structure could not fully develop [40]. However, the Ni/Fe-MOF samples still show a high crystalline phase under low synthesis temperatures.…”

“…The O 1s XPS spectra ( Figure 5C) could also be fitted into three peaks, which are (i) the peak at 533.8 eV corresponding to the O components on C=O/H2O, (ii) the peak at 532.3 eV attributed to the O components on the BDC linkers, and (iii) the peak at 530. 5 eV was assigned to the Both spectra were fitted into three peaks at a binding energy (BE) of 285.01, 288.9, and 291.7 eV, which could be assigned to the carbon components on the phenyl and the carboxylate groups of the BDC linkers [30,40,[44][45][46]. The O 1s XPS spectra ( Figure 5C) could also be fitted into three peaks, which are (i) the peak at 533.8 eV corresponding to the O components on C=O/H 2 O, (ii) the peak at 532.3 eV attributed to the O components on the BDC linkers, and (iii) the peak at 530.…”

Synthesis of Copper(II) Trimesinate Coordination Polymer and Its Use as a Sorbent for Organic Dyes and a Precursor for Nanostructured Material

“…In addition, many organic dyes contain chemicals that are toxic or carcinogenic to mammals and other living organisms [6,7]. An important problem is also the non-biodegradable nature of some dyes and their resistance to light 2 of 22 and oxidizing agents [8,9]. Methylene blue (MV), Congo red (CR) and methyl violet (MV) are some of the most common organic dyes present in wastewater and industrial effluents.…”

Polyaniline coated hematite sand supported on graphene oxide (HS@PANI‐GO) as a new magnetic material for advanced catalytic oxidation based on sulfate radicals: optimization using response surface methodology

“…Among these AOPs are, photocatalysis, electrocatalysis, photo‐electrocatalysis, electro‐Fenton, Fenton, peroxicoagulation, photo‐Fenton, sono‐Fenton, sonochemical methods, hydrodynamic cavitation, zero valent metals based AOPs, and oxidation processes based on the use of radicals (SO 4 −• , OH • ) . However, the oxidation by the radicals of sulfate SO 4 −• attracted a lot of attention because of the high oxidation potential that is expected at 2.01 V compared to others radicals . In addition, the high stability and the low cost of these radicals make this process interesting from an environmental and economical point of view .…”