Magnetic Nanoscaled Fe₃O₄/CeO₂ Composite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of 4-Chlorophenol

Abstract

Magnetic nanoscaled Fe(3)O(4)/CeO(2) composite was prepared by the impregnation method and characterized as a heterogeneous Fenton-like catalyst for 4-chlorophenol (4-CP) degradation. The catalytic activity was evaluated in view of the effects of various processes, pH value, catalyst addition, hydrogen peroxide (H(2)O(2)) concentration, and temperature, and the pseudo-first-order kinetic constant of 0.11 min(-1) was obtained for 4-CP degradation at 30 °C and pH 3.0 with 30 mM H(2)O(2), 2.0 g L(-1) Fe(3)O(4)/CeO(2), and 0.78 mM 4-CP. The high utilization efficiency of H(2)O(2), calculated as 79.2%, showed a promising application of the catalyst in the oxidative degradation of organic pollutants. The reusability of Fe(3)O(4)/CeO(2) composite was also investigated after six successive runs. On the basis of the results of metal leaching, the effects of radical scavengers, intermediates determination, and X-ray photoelectron spectroscopic (XPS) analysis, the dissolution of Fe(3)O(4) facilitated by CeO(2) played a significant role, and 4-CP was decomposed mainly by the attack of hydroxyl radicals (•OH), including surface-bound •OH(ads) generated by the reaction of Fe(2+) and Ce(3+) species with H(2)O(2) on the catalyst surface, and •OH(free) in the bulk solution mainly attributed to the leaching of Fe.

Spatial Confinement of a Co3O4 Catalyst in Hollow Metal–Organic Frameworks as a Nanoreactor for Improved Degradation of Organic Pollutants

“…The 4-CP removal can reach about 100% within 30, 60, and 120 min at the PMS concentration of 0.8 mM, 0.4 mM, and 0.15 mM, respectively. Further increasing the PMS concentration did not increase the degradation efficiency but resulted in a slight inhibition perhaps due to the self-quenching of SO 4 •− by excess PMS. 34 Meanwhile, neutral or alkalescent initial pH conditions exhibit a slightly superior 4-CP removal performance than acidic conditions ( Figure S7b) in this reaction process.…”

“…8,9 For SO 4 •− production, the combination of transition metal ions with peroxymonosulfate (PMS) is highly efficient, and cobalt ions have been found to be the best activator in this system. 10 While considering the disadvantages of homogeneous process associated with the precipitation of metal salts and the difficulty in catalyst recycling, researchers deflect to develop heterogeneous cobalt based catalysts.…”

“…15 We thus conceived that encapsulating the Co oxides into a proper hollow nanostructure to form a unique yolk−shell nanoreactor, which has been rarely investigated to date, would perfectly address the above-mentioned construction obstacles. In particular, the porous shell of the hollow nanostructure can impede the aggregation of adjacent Co oxides NPs and protect the enfolded catalyst from outside harsh environment without influencing the transport of reactants and products, while its interior cavity can preserve all the exposed catalytic sites accessible to reactants and provide microenvironment to accommodate the SO 4 •− oxidation reaction. More interestingly, enveloping catalytic reactions into a specific confined space would display improved catalytic performance due to the confinement effect, which has been confirmed by several previous studies including ours.…”

Preparation of magnetite-based catalysts and their application in heterogeneous Fenton oxidation – A review

“…That was mainly attributed to iron leaching (≈1 mg L -1 ). Xu and Wang (2012b) [108] also found a loss of activity upon 6 runs (from 100% to 40% conversion for 1 st to 6 th runs, respectively) in In contrast to the relatively low stability of some nanocomposites, Niu et al (2011) [110] demonstrated that humic acid-coated MNPs present a remarkable stability in CWPO of sulfathiazole, maintaining complete conversion upon 3 successive runs. However, these authors did not provide information about TOC reduction upon sequential cycles.…”

Analytical Method for the Determination of Trace Toxic Elements in Milk Based on Combining Fe3O4 Nanoparticles Accelerated UV Fenton-like Digestion and Solid Phase Extraction

“…On the basis of the observations from previous studies [24][25][26]39 and the above study, the reaction mechanism may consist of a dominant digestion and a subsidiary digestion, which have occurred on the surface of MNPs and in the leaching solution, respectively. Figure 1A,B shows that the mixture can be digested to some extent in the 30,80, and 120 nm were tested to digest the milk mixture under the same experimental conditions, as shown in Figure 2.…”