Degradation of Organic Dyes over Fenton-Like Cu2O–Cu/C Catalysts

Facile Fabrication of a Novel Copper Nanozyme for Efficient Dye Degradation

In this study, a novel copper nanozyme (CNZ) was synthesized by a mild way and characterized by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). The as-fabricated CNZ exhibited typical peroxidase activity toward 2, 2'-azinodi-(3-ethylbenzthiazoline)-6-sulfonate. We successfully applied CNZ for the degradation of methyl orange pollutants. Under the optimum conditions (pH, 3.0; T, 60 °C; H2O2 concentration, 200 mM; dosage of CNZ, 8 mg), 93% of the degradation rate could be obtained in less than 10 min. Furthermore, the nanozyme exhibited excellent reusability and storage stability. All these experimental results suggested that CNZ is a powerful catalyst for industrial wastewater treatment.

Self-Enhanced Decomplexation of Cu-Organic Complexes and Cu Recovery from Wastewaters Using an Electrochemical Membrane Filtration System

Heavy metals in industrial wastewaters are typically present as stable metal-organic complexes with their cost-effective treatment remaining a significant challenge. Herein, a self-enhanced decomplexation scenario is developed using an electrochemical membrane filtration (EMF) system for efficient decomplexation and Cu recovery. Using Cu-EDTA as a model pollutant, the EMF system achieved 81.5% decomplexation of the Cu-EDTA complex and 72.4% recovery of Cu at a cell voltage of 3 V. The ^•OH produced at the anode first attacked Cu-EDTA to produce intermediate Cu-organic complexes that reacted catalytically with the H₂O₂ generated from the reduction of dissolved oxygen at the cathode to initiate chainlike self-enhanced decomplexation in the EMF system. The decomplexed Cu products were further reduced or precipitated at the cathodic membrane surface thereby achieving efficient Cu recovery. By scavenging H₂O₂ (excluding self-enhanced decomplexation), the rate of decomplexation decreased from 8.8 × 10^-1 to 4.1 × 10^-1 h^-1, confirming the important role of self-enhanced decomplexation in this system. The energy efficiency of this system is 93.5 g kWh^-1 for Cu-EDTA decomplexation and 15.0 g kWh^-1 for Cu recovery, which is much higher than that reported in the previous literature (i.e., 7.5 g kWh^-1 for decomplexation and 1.2 g kWh^-1 for recovery). Our results highlight the potential of using EMF for the cost-effective treatment of industrial wastewaters containing heavy metals.

Construction of a novel Cu2(OH)3F/g-C3N4 heterojunction as a high-activity Fenton-like catalyst driven by visible light

Inhibiting the competitive effect of O₂ in copper-based Fenton reagents and improving the photogenerated electron–hole pair separation of g-C₃N₄ are the focus of current research.

Green synthesized iron nanoparticles as highly efficient fenton-like catalyst for degradation of dyes

Iron nanoparticles (Fe NPs) were synthesized herein through a simple and eco-friendly method using FeCl₃ and aqueous plant extract (dimocarpus longan, DL). Compared with Fe NPs prepared via traditional chemical methods, this biogenetic DL-Fe NPs demonstrates higher catalytic activity in Fenton-like reaction to degrade methyl orange (MO) in a wide pH range. It's worth noting that the DL-Fe NPs manifest a superior stability even after storage for at least 28 days. Systematic characterizations indicate that the active biomolecules from plant extract significantly contribute to the superior performance of DL-Fe NPs, by facilitating the dye molecules to be adsorbed on the surfaces of DL-Fe NPs, and providing a stable acid environment for the Fenton-like catalytic reaction. The kinetics study demonstrates this removal process conforms to the pseudo first-order model with the reaction activation energy of 41.6 kJ/mol. Moreover, various typical dyes including congo red, malachite green, methylene blue, eosin-Y and rhodamine B can be dramatically degraded by this DL-Fe NPs with a satisfactory removal efficiency.

Smart Porous Core-Shell Cuprous Oxide Nanocatalyst with High Biocompatibility for Acid-Triggered Chemo/Chemodynamic Synergistic Therapy

The rational integration of chemotherapy and hydroxyl radical (·OH)-mediated chemodynamic therapy (CDT) holds great potential for cancer treatment. Herein, a smart biocompatible nanocatalyst based on porous core-shell cuprous oxide nanocrystals (Cu₂ O-PEG (polyethylene glycol) NCs) is reported for acid-triggered chemo/chemodynamic synergistic therapy. The in situ formed high density of hydrophilic PEG outside greatly improves the stability and compatibility of NCs. The porosity of Cu₂ O-PEG NCs shows the admirable capacity of doxorubicin (DOX) loading (DOX@Cu₂ O-PEG NCs) and delivery. Excitingly, Cu (Cu^+/2+ ) and DOX can be controllably released from DOX@Cu₂ O-PEG NCs in a pH-responsive approach. The released Cu⁺ exerts Fenton-like catalytic activity to generate toxic ·OH from intracellular overexpressed hydrogen peroxide (H₂ O₂ ) for CDT via reactive oxygen species (ROS)-involved oxidative damage. Exactly, DOX can not only induce cell death for chemotherapy but also enhance CDT by self-supplying endogenous H₂ O₂ . After the intravenous injection, Cu₂ O-PEG NCs can effectively accumulate in tumor region via passive targeting improved by external high-density PEG shell. Additionally, the effect of boosted CDT combined with chemotherapy presents excellent in vivo antitumor ability without causing distinct systemic toxicity. It is believed that this smart nanocatalyst responding to the acidity provides a novel paradigm for site-specific cancer synergetic therapy.

Superior dye degradation and adsorption capability of polydopamine modified Fe3O4-pillared bentonite composite

Owing to the increasing demand of environmentally benign materials for the degradation of hazardous dyes, herein we are reporting two different synthesis approaches for the fabrication of iron loaded bentonite composites by modifying and activating bentonite surface with polydopamine (PDA) followed by pillaring with Fe³⁺ (Fe-PDA-bentonite) and Fe₃O₄ (Fe₃O₄-PDA-bentonite). Both the composites were assessed for their adsorption and degradation performance using crystal violet (CV), Rhodamine B and Brilliant blue dyes following adopting advanced oxidation process type Fenton reaction under variable energy sources (Sunlight, UV light and Ultrasonication), concentration of H₂O₂ and catalyst dosage. Under UV light irradiation, the composites achieved complete degradation of the dyes within 60 min and showed degradation rate constant of 30.5E-3-81.8E-3. Textural characterizations of the composites were achieved via XRD, FTIR, TGA, XPS, SEM-EDX, TEM, N₂ adsorption, VSM and UV/Vis spectrophotometry. The adsorption data of CV over the two composites fitted well with Langmuir adsorption isotherm, exhibiting the maximum adsorption capacity of 862 mg/g and 1235 mg/g for Fe-PDA-bentonite and Fe₃O₄-PDA-bentonite composites respectively. LCMS analysis of the post degradation products revealed that both the composites followed different degradation pathways and Fe₃O₄-PDA-bentonite showed superior photocatalytic performance by accomplishing complete dye degradation without leaving any degradation products. FTIR analysis of the post-degradation composites confirmed their structural stability with negligible iron leaching. This study, accredited to its cost-effectiveness, ease of operation and high efficiency, provides useful reference information for the degradation of dyes on industrial level.

A pH-activated autocatalytic nanoreactor for self-boosting Fenton-like chemodynamic therapy

The emergence of hydroxyl radical (˙OH)-mediated chemodynamic therapy (CDT) by the Fenton or Fenton-like reaction holds great potential for improving anticancer efficacy. Herein, an activatable autocatalytic nanoreactor (HT@GOx-DMONs) was developed for self-boosting Fenton-like CDT via decorating Cu²⁺-based metal-organic frameworks (MOFs) on glucose oxidase (GOx)-loaded dendritic mesoporous organosilica nanoparticles (DMONs) for the first time. The obtained nanoreactor could prevent the premature leakage of Cu²⁺ and GOx in neutral physiological environments conducted by the gatekeeper of growing carboxylate MOF (HKUST-1), but the explosive release of agents was realized due to the activated degradation of external HKUST-1 in acidic condition of endo/lysosomes, which thereby endowed this nanoreactor with the performance of pH-triggered ˙OH generation driven by Cu⁺-mediated autocatalytic Fenton-like reaction. Excitingly, Cu²⁺-induced glutathione (GSH) depletion and GOx-catalyzed H₂O₂ self-sufficiency unlocked by acid dramatically enhanced ˙OH generation. As expected, the effect of self-amplified CDT based on Cu²⁺-containing HT@GOx-DMONs presented wonderful in vitro toxicity and in vivo antitumor ability without leading to significant side-effects. The resulting nanoreactor with GSH consumption and H₂O₂ self-supply activated by acid may provide a promising paradigm for on-demand CDT.

Efficient and stable catalysis of hollow Cu9S5 nanospheres in the Fenton-like degradation of organic dyes

The development of new heterogeneous catalysts with stable catalytic activity in a wide pH range to prevent polluting precipitation plays a vital role in large-scale wastewater treatment. Here, a facile anion exchange strategy was designed to fabricate hollow Cu₉S₅ nanospheres by using Cu₂O nanospheres as hard-templates. The structural and compositional transformation from Cu₂O nanospheres to hollow Cu₉S₅ nanospheres were investigated via X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The Fenton-like degradation of organic dyes was used to evaluate the catalytic performance of the obtained Cu-containing catalysts. Results reveal that the hollow Cu₉S₅ nanospheres have the best catalytic activity among five kinds of Cu-containing catalysts. Hollow Cu₉S₅ nanospheres can effectively accelerate the decomposition of H₂O₂ into hydroxyl radicals and superoxide radical, which have been proven to be mainly oxidative species in the Fenton-like degradation of organic pollutants. Hollow Cu₉S₅ nanospheres have a wide pH application range of 5.0-9.0, and their extremely stable activity can be maintained in at least 15 catalytic cycles with a Cu²⁺ ion leaching rate of less than 1.0 %. The outstanding catalytic performance of the Cu₉S₅ catalyst is expected to enhance the practical applications of copper sulfide catalysts in Fenton-like wastewater treatment.

MOFs derived Co/Cu bimetallic nanoparticles embedded in graphitized carbon nanocubes as efficient Fenton catalysts

In this work, Cu-Co bimetallic nanoparticles embedded carbon nanocubes (Cu_xCo_10-x/CNC) are synthesized by direct carbonization of Cu-Co bimetal ZIF. The ratio of Cu and Co nanoparticles in Cu_xCo_10-x/CNC as well as morphology, pore structure and graphitization degree of carbon substrates can be tuned by adjusting the molar ratio of Cu/Co (0:10, 1:9, 2:8, 3:7, 4:6 and 5:5) in ZIF precursors. The Fenton catalytic performances of Cu_xCo_10-x/CNC are further studied by degrading a typical azo dye, Acid Orange II (AOII). The results show the Cu_xCo_10-x/CNC with a Cu/Co ratio of 4/6 display the highest catalytic activity with faster dye degradation rate than other catalysts, which may be ascribed to the synergetic effects of optimized ratio of Cu/Co bimetals, high surface area and graphitized carbon framework. The stability and reusability of the catalyst has been investigated, showing a good performance after five consecutive runs. The catalysts prepared in this study can be used as an attractive alternative in heterogeneous Fenton chemistry and wastewater treatment.

Controlled Synthesis of Manganese Oxide Nanoparticles Encaged in Hollow Mesoporous Silica Nanoreactors and Their Enhanced Dye Degradation Activity

In this study, controlled synthesis of hollow mesoporous silica nanoreactors with small manganese oxide nanoparticles in their cavities (Mn _x O _y @HMSNs) is reported, and the dye degradation performance in the presence of hydrogen peroxide over Mn _x O _y @HMSNs is investigated. Specifically, triple ligands (a compound with three dipicolinic acid groups) were used to coordinate manganese ions to form negatively charged coordination complex networks, which further combine with positively charged copolymers to obtain metal ion-containing polymer micelles. Following silica deposition onto micellar coronas and calcinations simultaneously result in hollow mesoporous silica nanoreactors and manganese oxide nanoparticles in their cavities. In this work, the influences of synthetic parameters on the structures are studied in detail. The obtained Mn _x O _y @HMSNs show greatly enhanced activity and stability for a series of dye degradations. The performance enhancement is ascribed to their unique nanostructures, where mesoporous silica walls provide protection to the inner Mn _x O _y nanoparticles and the small size of the manganese oxide nanoparticles greatly enhances the dye degradation activity.

A Fenton-Like Nanocatalyst Based on Easily Separated Magnetic Nanorings for Oxidation and Degradation of Dye Pollutant

In this study, uniform Fe₃O₄ magnetic nanorings (Fe₃O₄-MNRs) were prepared through a simple hydrothermal method. The morphology, magnetic properties, and structure of the product were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The Fe₃O₄-MNRs were used as Fenton-like catalysts in the presence of hydrogen peroxide (H₂O₂) and showed excellent Fenton-catalytic activity for degradation of organic dyes such as Methylene blue (MB), Rhodamine B (RhB), and Bromophenol blue (BPB). Furthermore, the obtained Fe₃O₄-MNRs could be recycled after used for several times and still remained in a relative high activity and could rapidly be separated from the reaction medium using a magnet without considerable loss. All results reveal that Fe₃O₄-MNRs have potential for the treatment of dyes pollutants.

Hierarchically porous BiOCl@NiCo2O4 nanoplates as low-cost and highly efficient catalysts for the discoloration of organic contaminants in aqueous media

BiOCl@NiCo₂O₄ exhibits remarkable catalytic activity and stability and can be used to deal with real contaminated water samples.

Heterogeneous Bimetallic Cu–Ni Nanoparticle-Supported Catalysts in the Selective Oxidation of Benzyl Alcohol to Benzaldehyde

Three bimetallic Cu–Ni nanoparticle-supported catalysts were synthesized by co-immobilization followed by H2 reduction. A chromium(III) terephthalate metal organic framework (MIL-101), titanium dioxide (TiO2), and carbon (C) with different properties (acidity and Brunauer–Emmett–Teller surface area) were selected as supports for studying the effect of the support nature on the catalytic activity and selectivity in the oxidation of benzyl alcohol. The physicochemical properties of the Cu–Ni-supported catalysts were characterized by XRD, NH3-TPD, nitrogen adsorption/desorption, TEM, EDS, XPS, and ICP-OES. Bimetallic Cu–Ni nanoparticles were highly dispersed on the support. The catalytic activities of CuNi/MIL-101, CuNi/TiO2, and CuNi/C were tested in the selective oxidation of benzyl alcohol to benzaldehyde in the presence of molecular oxygen under mild reaction conditions. The highest benzaldehyde yields were achieved with CuNi/TiO2, CuNi/MIL-101, and CuNi/C catalysts at 100 °C within 4 h under 5, 3, and 3 bar of O2, respectively. The bimetallic Cu–Ni-supported catalysts possessed two types of catalytic active sites: acid sites and bimetallic Cu–Ni nanoparticles. The CuNi/MIL-101 catalyst possessed a high number of acid sites and exhibited high yield during selective benzyl alcohol oxidation to benzaldehyde. Importantly, the catalysts exhibited a high functional group (electron-donating and electron-withdrawing groups) tolerance. Cu–Ni-supported catalysts with an Cu:Ni mole ratio of 1:1 exhibited the highest yield of 47% for the selective oxidation of benzyl alcohol to benzaldehyde. Reusability and leaching experiment results exhibited that CuNi/MIL-101 showed better stability than CuNi/TiO2 and CuNi/C catalysts due to the large porous cavities of MIL-101 support; these cavities can be used to trap bimetallic Cu–Ni nanoparticles and inhibit nanoparticle leaching.

Enhanced Removal of Veterinary Antibiotic Florfenicol by a Cu-Based Fenton-like Catalyst with Wide pH Adaptability and High Efficiency

The study on the removal of refractory veterinary antibiotic florfenicol (FF) in water is still very limited. In this study, an efficient Fenton-like catalyst was developed by synthesizing a series of Cu-based multi-metal layered double hydroxides (CuNiFeLa-LDHs) to degrade FF in aqueous solution. In the experiments, the screened CuNiFeLa-2-LDH with the molar ratio of La³⁺/(Fe³⁺ + La³⁺) = 0.1 exhibited high catalytic activity, achieving almost complete degradation of 5 mg L^-1 FF under 5 mmol L^-1 H₂O₂ conditions. The mechanisms revealed that the enhanced catalytic performance was ascribed to the existence of Ni which accelerated the electron transfer rate and La which served as a Lewis acidic site to provide more reactive sites in this Cu-dominated Fenton-like reaction, further generating ^•OH, ^•O₂ ^-, and O₂ ¹ as active species to attack pollutants directly. Interestingly, the catalyst showed a wide pH adaptability and little release of copper ions to the solution. The regenerated CuNiFeLa-2-LDH is demonstrated to be a stable and reliable material for florfenicol degradation.

A noble bimetal oxysulfide CuVOS catalyst for highly efficient catalytic reduction of 4-nitrophenol and organic dyes

A novel CuVOS catalyst was successfully synthesized by a facile method. The CuVOS with optimum amount of N₂H₄ had higher catalytic activity.

UV-Curable Hydrophobic Coatings of Functionalized Carbon Microspheres with Good Mechanical Properties and Corrosion Resistance

Polyurethane acrylates (PUAs) are a kind of UV curable prepolymer with excellent comprehensive performance. However, PUAs are highly hydrophilic and when applied outdoors, presenting serious problems caused by rain such as discoloring, losing luster and blistering. Thus, it’s important to improve their hydrophobicity and resistance against corrosion. In this paper, carbon microspheres (CMSs) were modified through chemical grafting method. Active double bonds were introduced onto the surface of organic carbon microspheres (OCMSs) and the functional product was referred to as FCMS. The results of Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric analysis (TGA) showed that organic chain segments were successfully connected to the surface of OCMSs and the grafting efficiency was as high as 16%. FCMSs were successfully added into UV-curable polyurethane acrylate prepolymer to achieve a hydrophobic coating layer with good mechanical properties, thermal stability and corrosion resistance. When the addition of FCMSs were 1%, thermogravimetric analysis (TGA) results showed that 5% of the initial mass was lost at 297 °C. The water absorption decreased from 52% to 38% and the water contact angle of the PUA composite increased from 72° to 106°. The pencil hardness increased to 4H and obvious crack termination phenomenon was observed in SEM images. Moreover, the corrosion rate was decreased from 0.124 to 0.076 mm/a.