Enhanced Photo-Fenton Activity Using Magnetic Cu0.5Mn0.5Fe2O4 Nanoparticles as a Recoverable Catalyst for Degrading Organic Contaminants

Abstract

Interest in using various nanoparticle catalysts to activate H2O2 with light for organic contaminant and wastewater treatment is steadily increasing. We successfully synthesized magnetically recoverable Cu0.5Mn0.5Fe2O4 nanoparticles using a simple co-precipitation method followed by melamine-assisted calcination. Material characterization revealed that melamine acted as a coordinating agent during the calcination process that promoted a ferrite structure. Copper (Cu)-substitution effectively decreased material aggregation and promoted catalytic activities. Cu0.5Mn0.5Fe2O4 nanoparticles showed outstanding catalytic performance on several organic contaminants (87.6–100.0% removal within 2 h). Using oxytetracycline (OTC) as a surrogate wastewater constituent, we found that the hydroxyl radical (•OH) and superoxide anions (•O2−) were the active radical species involved in OTC degradation. Cu0.5Mn0.5Fe2O4 nanoparticles exhibited excellent photo-Fenton catalytic ability in real wastewater and demonstrated high material stability, even after four consecutive uses (i.e., fourth cycle). In a pilot-scale experiment (10 L), we provide proof that our rigorous treatment system was able to remove remnant OTC, TOC, and also any available colloidal particles to only 1 NTU. Ecotoxicity studies using an aquatic plant (Hydrilla verticillata) and zooplankton revealed that treated water could be reused in various ratios. Furthermore, at 5% of treated water, rapid leaf recovery and a significant increase in rotifer numbers were reported. These observations support the use of Cu0.5Mn0.5Fe2O4/H2O2/light as an efficient and environmentally friendly catalytic system for treatment of organic contaminants, and a radical generating mechanism is proposed.

Dual Activation of Peroxymonosulfate Using MnFe2O4/g-C3N4 and Visible Light for the Efficient Degradation of Steroid Hormones: Performance, Mechanisms, and Environmental Impacts

“… 26 Both XRD and FTIR results confirmed our successfully synthesized catalyst using coprecipitation followed by the melamine-assisted calcination method. Angkaew et al 27 reported that g-C 3 N 4 served as a coordinating agent by forming a metal–melamine complex and/or conjugating with a metal oxide. Under the calcining temperature (550 °C), this complex can further decompose into a spinel ferrite structure and volatile gases (i.e., CO X , NO X , and NH 3 ), successfully preventing α-Fe 2 O 3 formation.…”

“…If it was there, it might have been a rapid reaction, and the Fe 3+ was insufficient to react with a large amount of O 2 •– , thereby O 2 formation was only minimal. Moreover, Angkaew et al 27 showed that the ferrites also have photocatalytic performance and were able to produce • OH under light irradiation [ eq 8 ]. Because of the O 2 •– abundance, we ruled out that, once released, the • OH would simultaneously react and provide more 1 O 2 into the system, concordant with our scavenging experiment that rooted for 1 O 2 production.…”

“…By this synthesis method, the calcination of coprecipitate particles without the addition of melamine results in the formation of hematite (α-Fe 2 O 3 ) impurity, which significantly decreases the magnetic saturation value (M s ), resulting in poor recoverability of the prepared catalyst. 24,27 This was also confirmed by the FTIR spectra that showed huge adsorption peaks in 400−700 cm −1 region, which can be attributed to the metal−oxygen bonds (Fe−O, Mn−O) occupied at the tetrahedral and octahedral sites of the spinel structure. 26 Both XRD and FTIR results confirmed our successfully synthesized catalyst using coprecipitation followed by the melamine-assisted calcination method.…”

“…, thereby O 2 formation was only minimal. Moreover, Angkaew et al 27 showed that the ferrites also have photocatalytic performance and were able to produce • OH under light irradiation [eq 8].…”

Adsorptive–Photocatalytic Performance for Antibiotic and Personal Care Product Using Cu0.5Mn0.5Fe2O4

“…This is due to the various valences in the nanocomposites, including Mn 4+ , Mn 3+ , Mn 2+ , Fe 3+ , and Fe 2+ , which can trigger the synergistic action between the Mn and Fe redox cycles [10,11]. Furthermore, doping manganese ferrite structures with another transition metal (e.g., Cu) can produce ternary transition metal oxides (e.g., Cu 0.5 Mn 0.5 Fe 2 O 4 ), which have a greater surface area than iron-based transition metal catalysts [12,13]. This is beneficial to photo-Fenton-like AOP treatments by providing larger active sites, an excellent oxygen exchangeability, and an outstanding capability for electron transfer through the Cu 2+ /Cu 1+ redox cycle.…”