Activation of Peroxydisulfate by Ferrite Materials for Phenol Degradation

Abstract

Persulfates such as peroxydisulfate (PDS) are among the most widely applied oxidants for breaking down organic contaminants in water. The oxidation power arises from conversion of persulfate to sulfate radical or other reactive oxidants. Ferrite materials are good candidates for catalytic activation of persulfate owing to its ability to incorporate a variety of transition metals in the structure, stability against aqueous dissolution, and magnetic susceptibility allowing catalyst separation and reuse. In this study, ferrite spinels incorporating zinc, nickel, cobalt, or copper were synthesized with an epoxide-driven sol–gel method and were annealed at 350 and 700 °C, respectively. The particles were evaluated for activating PDS using phenol as a model organic contaminant. Cu-ferrite annealed at the low temperature (350 °C) was identified to be the most active ferrite for PDS activation. This solid consists of predominantly CuFe2O4, while at the higher annealing temperature, decomposition of CuFe2O4 to Fe2O3 and CuO and significant increase in particle size resulted in severe loss of PDS activation ability. Remarkable increases in phenol oxidation rate were observed above pH 9.0 and were attributed to PDS activation by phenoxide. The presence of methanol, bicarbonate, or chloride ion (1–5 mM) significantly slowed down phenol oxidation, whereas the addition of tert-butyl alcohol did not affect the degradation rate, indicating the dominant oxidant is sulfate radical. Comparison of Cu-ferrite against reference metal oxides suggests that the catalytic performance of Cu­(II) sites in the ferrite phase is comparable to those in the highly active but leachable CuO, and Cu-ferrite demonstrated good reusability during repeated phenol oxidation experiments.

Selective Oxidation of Various Phenolic Contaminants by Activated Persulfate via the Hydrogen Abstraction Pathway

“…Even as to recalcitrant phenolics such as nitrophenol and chlorophenol, the ratios of consumed PS and removed phenolics are always less than 2.0 (Figure S9), which is highly efficient compared with the oxidation of phenolics by PS and other heterogeneous catalysts (always greater than 4.0). 22,36 In addition, compared with that of CuO and PS, the oxidation consumption ratio in the CuO−PMS system is 2.43 at pH 8.0, implying that PS is more efficient than PMS for phenol oxidation. In addition, the prices of PS and PMS (in the form of oxone) are 0.18 and 1.36 USD mol −1 , respectively, 18 indicating that the stable PS is also more cost-effective than PMS for scale-up applications.…”

Superstructures with Atomic-Level Arranged Perovskite and Oxide Layers for Advanced Oxidation with an Enhanced Non-Free Radical Pathway

“…Catalysis plays a crucial role in many chemical processes, which has also received considerable attention in environmental remediation. ,− Of note, catalytic advanced oxidation processes (AOPs) have been recognized as a highly promising technology for the fast degradation of organic pollutants in wastewater, in particular for organic wastes that are hardly degradable through a conventional biodegradation process, such as dyes and textile assistants . AOP is a chemical method that applies a high-energy substance with strong oxidizing capability as an oxidant for the oxidative removal of organics in wastewater. , Typical oxidants include peroxymonosulfate (PMS), peroxydisulfate, and hydrogen peroxide (H 2 O 2 ), among which PMS is of particular interest due to its high redox capability, making it more efficient for organic degradation. − In the AOP, a catalyst (either homogeneous or heterogeneous) is often required to activate high-energy oxidants to reactive oxygen species (ROS), which can easily attack the organic wastes to break the chemical bonds and realize quick degradation . The exploration of low-cost, highly efficient, recyclable, and environmentally benign catalysts for the activation of high-energy oxidants holds key toward the development of AOPs for efficient wastewater remediation.…”

Research Progress and Prospects of Spinel Ferrite Nanostructures for the Removal of Nitroaromatics from Wastewater

“…The properties of ROS generation play a decisive role in photocatalysis to break the aromatic chain of organic pollutants . Peroxymonosulfate (PMS), hydrogen peroxide (H 2 O 2 ), and peroxydisulfate (PDS) are the highly explored oxidants for the optimization of catalytic activity of ferrites due to their high stability against magnetic susceptibility . H 2 O 2 has the disadvantages of expensive production, transport, and storage along with the requirement of a particular pH for reaction, while PMS can be handled easily and exhibits high reactivity in a wide pH range, higher oxidation potential, and environment friendliness .…”