Elimination of 4‐chlorophenol in aqueous solution by the Novel Pd/MIL‐101(Cr)‐Hydrogen‐Accelerated catalytic fenton system

Abstract

Excessive consumption of Fe (II) and massive generation of sludge containing Fe (III) from classic Fenton process remains a major obstacle for its poor recycling of Fe (III) to Fe (II). Therefore, the MHACF‐MIL‐101(Cr) system, by introducing H2, Pd0 and MIL‐101(Cr) into Fenton reaction system, was developed at normal temperature and pressure. In this system, the reduction of FeIII back to FeII by solid catalyst Pd/MIL‐101(Cr) for the storage and activation of H2, was accelerated significantly by above 10‐fold and 5‐fold controlled with the H2‐MIL‐101(Cr) system and H2‐Pd0 system, respectively. However, the concentration of Fe (II) generated by the reduction of Fe (III) could not be detected with the only input of H2 and without the addition of MOFs material. In addition, the apparent consumption of Fe (II) in MHACF‐MIL‐101(Cr) system was half of that in classical Fenton system, while more Fe (II) might be reused infinitely in fact. Accordingly, only trace amount of Fe (II) vs H2O2 concentration was needed and hydroxyl radicals through the detection of para‐hydroxybenzoic acid (p‐HBA) as the oxidative product of benzoic acid (BA) by·OH could be continuously generated for the effective degradation of 4‐chlorophenol(4‐CP). The effects of initial pH, concentration of 4‐CP, dosage of Fe2+, H2O2 and Pd/MIL‐101(Cr) catalyst, Pd content and H2 flow were investigated, combined with systematic controlled experiments. Moreover, the robustness and morphology change of Pd/MIL‐101(Cr) were thoroughly analyzed. This study enables better understanding of the H2‐mediated Fenton reaction enhanced by Pd/MIL‐101(Cr) and thus, will shed new light on how to accelerate Fe (III)/Fe (II) redox cycle and develop more efficient Fenton system.

Accelerated FeIII/FeII redox cycle of Fenton reaction system using Pd/NH2-MIL-101(Cr) and hydrogen

“…This may be attributed to the Pd 0 loaded on the surface of this MOFs material being shed off during the reaction with the structural damage of NH 2 -MIL-101(Cr) and the reduction of surface area, and then was gathered in aqueous solution. It was similar to our previous research results from MHACF-MIL-101(Cr) [44,45]. As established by the hard/soft acid/base principle, a more stable framework could be formed by high-valent metal cations by stronger coordination bonds.…”

“…•OH could be continuously generated by using only trace amount Ferrous ion in that system though the MIL-101(Cr) will be gradually damaged during the reaction process [44,45]. These two papers would serve as a basis for further studies on the subject matter, with particular concentrates on the reduction of iron sludge in Fenton system, and how improvements can be on suitable catalytic materials.…”

“…Infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), Brunner-Emmet-Teller measurements (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM) were same to those in our previous works [44,45].…”

“…TPd, H 2 O 2 , p-HBA and 4-CP are the same as previous study[7,44,45,59,60]. Quantitative analysis of p-Hydroxybenzoic acid (p-HBA) and 4-CP was performed with LC-20AT high performance liquid chromatography (Shimadzu, Japan) equipped with a reversed phase Agilent ZORBAX Eclipse XDB-C18 column(4.6 mm × 150 mm, 5 μm).…”

Critical Review on the Mechanisms of Fe2+ Regeneration in the Electro-Fenton Process: Fundamentals and Boosting Strategies

“…Compared to other reducing agents like metal- or metal-sulfide-based catalysts, active hydrogen (abbreviated as H*/[H]/H 2 ) is a clean reagent that has become a hot topic in environmental application, although it is still underplayed . H*, as a catalytic intermediate, is generally formed at the cathode during a two-electron transfer HER through either a Volmer–Heyrovsky or Volmer–Tafel mechanism.…”