Catalytic ozonation for degradation of sulfamethazine using NiCo2O4 as catalyst

Phosphorus-doped nickel cobalt oxide (NiCo2O4) wrapped in 3D hierarchical hollow N-doped carbon nanoflowers as highly efficient bifunctional electrocatalysts for overall water splitting

Properly design and fabricate capable electrocatalysts with 3D hierarchical hollow framework to realize cost-effective and efficacious overall water splitting (OWS) are particularly meaningful for the large-scale arrangement of pivotal energy technology. In this study, P-doped NiCo2O4 nanoparticles encapsulated in N-doped carbon hierarchical hollow nanoflowers (P-NiCo2O4@NCHHNFs) were constructed using the hydrothermal-pyrolysis-phosphorization approach. This fascinating architecture can not merely serve as a conductive pathway for electron transfer, but at the same time effectively inhibited the aggregation and corrosion of the NiCo2O4 nanoparticles. Additionally, the P doping not only regulates electronic structure configuration to boost the intrinsic activity of the catalyst, but also enhance electrochemical surface areas to reveal more accessible active sites. Attributing to these characteristics, the as-prepared P-NiCo2O4@NCHHNFs exhibit preeminent electrocatalytic performance with low overpotentials of 283 mV and 162 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) (at 10 mA cm-2), respectively. Specifically, by using the P-NiCo2O4@NCHHNFs as bifunctional catalysts, a low potential of 1.56 V (at 10 mA cm-2) is sufficient to drive overall water splitting with splendid durability. This study proposed an innovative strategy for the conceiving and fabricating high-performance catalysts via heteroatom-doping.

Degradation of Sodium Acetate by Catalytic Ozonation Coupled with MnOx/NiOOH-Modified Fly Ash

Fly ash, a type of solid waste generated in power plants, can be utilized as a catalyst carrier to enhance its value-added potential. Common methods often involve using a large amount of alkali for preprocessing, resulting in stable quartz and mullite forming silicate dissolution. This leads to an increased specific surface area and pore structure. In this study, we produced a catalyst composed of MnOx/NiOOH supported on fly ash by directly employing nickel hydroxide and potassium permanganate to generate metal active sites over the fly ash surface while simultaneously creating a larger specific surface area and pore structure. The ozone catalytic oxidation performance of this catalyst was evaluated using sodium acetate as the target organic matter. The experimental results demonstrated that an optimal removal efficiency of 57.5% for sodium acetate was achieved, surpassing even that of MnOx/NiOOH supported catalyst by using γ-Al2O3. After loading of MnOx/NiOOH, an oxygen vacancy is formed on the surface of fly ash, which plays an indirect oxidation effect on sodium acetate due to the transformation of ozone to •O2- and •OH over this oxygen vacancy. The reaction process parameters, including varying concentrations of ozone, sodium acetate, and catalyst dosage, as well as pH value and the quantitative analysis of formed free radicals, were examined in detail. This work demonstrated that fly ash could be used as a viable catalytic material for wastewater treatment and provided a new solution to the added value of fly ash.

Peracetic acid activated by nickel cobaltite as effective oxidizing agent for BPA and its analogues degradation

The presented research concerns the use of nickel cobaltite nanoparticles (NiCo2O4 NPs) for the heterogeneous activation of peracetic acid and application of NiCo2O4-PAA system for degradation 10 organic micropollutants from the group of bisphenols. The bisphenols removal (initial concentration 1 μM) process was optimized by selecting the appropriate process conditions. The optimal amount of catalyst (115 mg/L), peracetic acid (PAA) concentration (7 mM) and pH (7) were determined using response surface analysis in the Design of Experiment. Then, NiCo2O4 NPs were used to check the possibility of reuse in subsequent oxidation cycles. The work also attempts to explain the mechanism of oxidation of the studied micropollutants. The participation of the sorption process on the catalyst was excluded and based on the experiments with radical scavengers it can be concluded that the oxidation proceeds in a radical pathway, mainly with participation of O2•- radicals. Experiments conducted in real water matrices exhibit low impact on degradation efficiency. Toxicity tests with green alga Acutodesmus obliquus and aquatic plant Lemna minor showed that post-reaction mixture influenced growth and the content of photosynthetic pigments in concentration dependent manner.

Advanced treatment of secondary effluent by the integration of heterogeneous catalytic ozonation and biological aerated filter

The advanced treatment of secondary effluents was investigated by employing heterogeneous catalytic ozonation integrated with a biological aerated filter (BAF) process. The results indicated that catalytic ozonation with the prepared catalyst (Mn_xCu_yO_z/γ-Fe₂O₃) significantly enhanced the performance of pollutant removal and broke up macromolecules into molecular substances by the generated hydroxyl radicals. These molecular substances were easily absorbed by microorganisms in the microbial membrane reactor. In the BAF process, chemical oxygen demand (COD) (chemical oxygen demand) decreased from 54.26 to 32.56 mg/L, while in catalytic ozonation coupled with the BAF, COD could be reduced to 14.65 mg/L (removal ratio 73%). Under the same condition, NH₄⁺-N decreased from 77.43 to 22.69 mg/L and 15.73 mg/L (removal ratio 70%) in the BAF and the catalytic ozonation coupled with BAF, respectively. In addition, the model that highly correlated influent COD to effluent COD and reactor height for filler could predict the removal ratio of COD of the BAF system. Based on the microbial community analysis, ozone in the solution had a certain screening effect on microorganisms, which helped to better adapt to the ozone-containing environment. Therefore, the integrated process with its efficient, economic, and sustainable advantages was suitable for the advanced treatment of secondary effluents.

A comprehensive review on metal based active sites and their interaction with O3 during heterogeneous catalytic ozonation process: Types, regulation and authentication

Heterogeneous catalytic ozonation (HCO) was a promising water purification technology. Designing novel metal-based catalysts and exploring their structural-activity relationship continued to be a hot topic in HCO. Herein, we reviewed the recent development of metal-based catalysts (including monometallic and polymetallic catalysts) in HCO. Regulation of metal based active sites (surface hydroxyl groups, Lewis acid sites, metal redox cycle and surface defect) and their key roles in activating O₃ were explored. Advantage and disadvantage of conventional characterization techniques on monitoring metal active sites were claimed. In situ electrochemical characterization and DFT simulation were recommended as supplement to reveal the metal active species. Though the ambiguous interfacial behaviors of O₃ at these active sites, the existence of interfacial electron migration was beyond doubt. The reported metal-based catalysts mainly served as electron donator for O₃, which resulted in the accumulation of oxidized metal and reduced their activity. Design of polymetallic catalysts could accelerate the interfacial electron migration, but they still faced with the dilemma of sluggish Me^(n+m)+/Meⁿ⁺ redox cycle. Alternative strategies like coupling active metal species with mesoporous silicon materials, regulating surface hydrophobic/hydrophilic properties, polaring surface electron distribution, coupling HCO process with photocatalysis and H₂O₂ were proposed for future research.

State of Art and Perspectives in Catalytic Ozonation for Removal of Organic Pollutants in Water: Influence of Process and Operational Parameters

The number of organic pollutants detected in water and wastewater is continuously increasing thus causing additional concerns about their impact on public and environmental health. Therefore, catalytic processes have gained interest as they can produce radicals able to degrade recalcitrant micropollutants. Specifically, catalytic ozonation has received considerable attention due to its ability to achieve advanced treatment performances at reduced ozone doses. This study surveys and summarizes the application of catalytic ozonation in water and wastewater treatment, paying attention to both homogeneous and heterogeneous catalysts. This review integrates bibliometric analysis using VOS viewer with systematic paper reviews, to obtain detailed summary tables where process and operational parameters relevant to catalytic ozonation are reported. New insights emerging from heterogeneous and homogenous catalytic ozonation applied to water and wastewater treatment for the removal of organic pollutants in water have emerged and are discussed in this paper. Finally, the activities of a variety of heterogeneous catalysts have been assessed using their chemical–physical parameters such as point of zero charge (PZC), pKa, and pH, which can determine the effect of the catalysts (positive or negative) on catalytic ozonation processes.

Novel nanocomposite thin film in the efficient removal of antibiotics using visible light: Insights of photocatalytic reactions and stability of thin film in real water implications

Novel clay (bentonite) supported Ag⁰ nanoparticles (NPs) doped TiO₂ nanocomposite (Clay/TiO₂/Ag⁰(NPs)) thin film was obtained by using template synthesis method. The nanocomposite material is decorated with cubical Ag⁰(NPs) and utilised successfully in the photocatalytic degradation of tetracycline (TC) and sulfamethazine (SMZ) from aqueous solutions utilizing visible light and UV-A radiations. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) analyses were used to characterise the nanocomposite materials. Diffusion reflectance spectroscopy (DRS) was utilised to determine the bandgap energies of the materials and also to confirm that Ag⁰(NPs) was successfully doped with TiO₂. The nanocomposite material showed highly efficient photocatalytic activity for the breaking down of TC/SMZ under visible light irradiation by the enhanced electron-hole separation and adsorption of antibiotics at the vicinity of the catalyst. The oxidative degradation of TC/SMZ were shown to be highly dependent on the pH, initial concentration of TC/SMZ, and various co-existing ions. Reusability test of Clay/Ag⁰(NPs)/TiO₂ nanocomposite revealed that the activity did not decline with repeated use. Treatment of TC and SMZ in real water system further enhanced the application potential of the novel catalysts for the treatment of full-scale wastewater polluted with these antibiotics.

Improvement of coal gasification reverse osmosis concentrate treatment by Cu-Co-Mn/AC catalytic ozonation

Approximately 20% of concentrate will be produced from coal gasification wastewater after reverse osmosis treatment. The organic matter contained in the concentrate affects its evaporation crystallisation; therefore, the refractory organics must be removed. In this study, Cu-Co-Mn/AC catalytic ozonation was used to treat reverse osmosis concentrate (ROC). With the addition of the Cu-Co-Mn/AC catalyst, the production of ·OH increased by 82 μmol/L, thereby enhancing the ozonation performance. The pH, ozone dosage, and catalyst dosage all affected the catalytic ozonation performance. By constructing a response surface model, it was found that the catalyst dosage had the most significant effect on the catalytic ozonation performance. The predicted optimal reaction conditions were pH = 9.02, ozone dosage = 1.08 g/L, and catalyst dosage = 1.33 g/L, under which the chemical oxygen demand (COD) removal reached a maximum of 81.49%.

Ni-based catalysts used in heterogeneous catalytic ozonation for organic pollutant degradation: a minireview

Among various advanced oxidation processes for wastewater treatment, heterogeneous catalytic ozonation (HCO) has a growing interest in pollutant degradation, e.g., pesticides, pharmaceuticals, cresols, detergents, polymers, dyes, and others. Direct oxidation with ozone can occur by this route or indirectly, generating reactive oxygen species through the catalytic activation of the ozone molecule. Then, many catalytic materials were evaluated, such as unsupported and supported oxides, activated carbon, nanocarbons, carbon nitride, and mesoporous materials. This review focuses on the properties and performance of Ni-based catalysts (NiO, supported NiO, Ni ferrites, and M-Ni bimetallic), emphasizing the reaction mechanisms and the importance of the reactive oxygen species in removing toxic organic compounds.

Comparative evaluation of MSW incineration leachate treatment by heterogeneous catalytic O3 and UV/O3: The unexpected contribution of high salinity and overlooked role of excited state

The efficiency and mechanism of heterogeneous catalytic O₃ and UV/O₃ for municipal solid waste (MSW) incineration leachate advanced treatment was systematically compared. Prior to comparison, catalyst used in heterogenous catalytic O₃ and operation parameters for each technology were optimized. The COD removal of CuO@Al₂O₃/O₃ under its optimal parameters was 57.2%, which failed to meet the standard (≥75%). In contrast, the COD removal by UV/O₃ could be 82.3%. The superior efficiency of UV/O₃ over CuO@Al₂O₃/O₃ could be summarized into three aspects: (I) Cu bounded ·OH (≡Cu-O·) preferentially attacked hydrophilic groups, while free hydroxyl radical (·OH) was non-selective, thus UV/O₃ exhibited a unique three-stage mechanism; (II) The oxidation potential of ≡Cu-O· was higher than that of ·OH, therefore was more vulnerable to the negative effect of radical self-quenching; (III) The existence of UV-induced excited states made organics in UV/O₃ more active than in CuO@Al₂O₃/O₃ system, thus high concentration of anions enhanced COD removal in UV/O₃ but affected that in CuO@Al₂O₃/O₃. The study further revealed the characteristics of heterogeneous catalytic O₃ and UV/O₃, and UV induced excited state should be considered in UV-based advanced oxidation processes (AOPs).

Prediction of pharmaceutical and personal care products elimination during heterogeneous catalytic ozonation via chemical kinetic model

Prediction of the removal of pollutants is important for the process design and optimization of wastewater treatment. In this study, the heterogeneous catalytic ozonation chemical kinetic model based on reaction kinetic constants between O₃ (and •OH) and pollutants, and pseudo-first order rate constants for pollutant adsorption was established. The model parameters were obtained via O₃ and p-chlorobenzonic acid decay curves, and adsorption kinetic experiments, respectively. Higher •OH exposures were obtained at the expense of lower O₃ exposures during catalytic ozonation compared to simple ozonation. Importantly, the experimentally measured and model-predicted removal ratios correlated well in all reaction systems, with correlation coefficients above 0.950 in synthetic solution and 0.893-0.979 in secondary effluent. Furthermore, the model revealed that pollutants were degraded mainly by O₃ and/or •OH oxidation during catalytic ozonation, while adsorption of pollutants on catalysts contributed negligibly. Hence, the degradation ratios of pollutants could be satisfactorily predicted using the simplified model based only on the O₃ and •OH exposures in the heterogeneous catalytic ozonation systems with low adsorption capacity catalysts.

SARS-CoV-2 pharmaceutical drugs: a critical review on the environmental impacts, chemical characteristics, and behavior of advanced oxidation processes in water

This review summarizes research data on the pharmaceutical drugs used to treat the novel SARS-CoV-2 virus, their characteristics, environmental impacts, and the advanced oxidation processes (AOP) applied to remove them. A literature survey was conducted using the electronic databases Science Direct, Scopus, Taylor & Francis, Google Scholar, PubMed, and Springer. This complete research includes and discusses relevant studies that involve the introduction, pharmaceutical drugs used in the SARS-CoV-2 pandemic: chemical characteristics and environmental impact, advanced oxidation process (AOP), future trends and discussion, and conclusions. The results show a full approach in the versatility of AOPs as a promising solution to minimize the environmental impact associated with these compounds by the fact that they offer different ways for hydroxyl radical production. Moreover, this article focuses on introducing the fundamentals of each AOP, the main parameters involved, and the concomitance with other sources and modifications over the years. Photocatalysis, sonochemical technologies, electro-oxidation, photolysis, Fenton reaction, ozone, and sulfate radical AOP have been used to mineralize SARS-CoV-2 pharmaceutical compounds, and the efficiencies are greater than 65%. According to the results, photocatalysis is the main technology currently applied to remove these pharmaceuticals. This process has garnered attention because solar energy can be directly utilized; however, low photocatalytic efficiencies and high costs in large-scale practical applications limit its use. Furthermore, pharmaceuticals in the environment are diverse and complex. Finally, the review also provides ideas for further research needs and major concerns.

Novel sphere-like copper bismuth oxide fabricated via ethylene glycol-introduced solvothermal method with improved adsorptive and photocatalytic performance in sulfamethazine removal

In this research, ethylene glycol-introduced solvothermal method was employed to fabricate a novel sphere-like CuBi₂O₄ material to improve the adsorptive and photocatalytic performance of conventional CuBi₂O₄. A series of characterization has been applied to investigate properties of the obtained CuBi₂O₄ (CBO-EG3). Compared with conventional rod-like CuBi₂O₄ (CBO), the synthesized sphere-like CBO-EG3 exhibited rough surface, larger specific surface area, and more effective separation of photo-generated carriers, which overcome main shortcomings of CuBi₂O₄. The removal efficiency of typical antibiotic sulfamethazine (SMZ) reached almost 100% under the optimal experimental conditions. About 70% of SMZ could be adsorbed in 180-min dark reaction, with residual being photodegraded in 30 min. CBO-EG3 showed much higher photocatalytic efficiency than pure CBO, attributing to its highly effective photo-induced electron and hole separation. Meanwhile, substantial adsorption of pollutant on CBO-EG3 contributed vastly to removal of SMZ, photo-generated electrons and holes inclined to react with adsorbed SMZ directly, and photocatalytic process was mainly led by non-radical reaction. Elimination of SMZ in actual water samples and recycling experiment were also performed to evaluate CBO-EG3's practical application potential. This study delivered a method to promote CuBi₂O₄'s adsorptive and photocatalytic ability, which could expand the application of CuBi₂O₄ in wastewater treatment.

In-situ growth of Co/Ni bimetallic organic frameworks on carbon spheres with catalytic ozonation performance for removal of bio-treated coking wastewater

The Co/Ni-MOFs@CS composite derived from Co/Ni bimetallic organic framework was synthesized and characterized. Compared with a single O₃ system, the synergy between carbon sphere (CS) and metal organic frameworks (MOFs) improved the electron transfer efficiency and the formation rate of •OH. The coexistence of Co and Ni in various valence states might accelerate the cyclic process of Co(II)/Co(III) and Ni(II)/Ni(III), thereby improving the catalytic activity. Taking levofloxacin as a model pollutant, the mechanism of catalytic process was discussed, and the catalytic reaction was successfully applied to the removal of residual organics in bio-treated coking wastewater (BTCW). The removal rates of chemical oxygen demand (COD) and total organic carbon (TOC) in 60 min were 50.85%-53.71% and 39.98%-43.48%. From the perspective of UV absorption and 3D EEM, catalytic ozonation was more conducive to breaking the electronic protection of inert organic molecules such as heterocyclic compounds, and achieving higher efficiency of mineralization. It provides a new idea for catalytic ozonation technology of wastewater treatment in the future from theory, technology and application.

Catalytic ozonation performance and mechanism of Mn-CeOx@γ-Al2O3/O3 in the treatment of sulfate-containing hypersaline antibiotic wastewater

Herein, we attempted to apply an alumina-based bimetallic (Mn-Ce) catalyst as an O₃ activator and explored the feasibility of the treatment of hypersaline organic wastewater. Compared with independent O₃ (35.00 ± 4.20%), mineralization of ciprofloxacin (CIP) under the Mn-CeO_x@γ-Al₂O₃/O₃ (MCAO) process was elevated to 76.04 ± 2.30%. The synergetic corporation among multivalence redox pairs of Mn (III)/Mn (IV), Ce (III)/Ce (IV) promoted the protonation of the surface hydroxyl group (S-OH₂⁺), and subsequently the dominant reactive oxygen species in the MCAO process, OH and O₂^-, were generated rapidly. However, the mineralization of CIP decreased in MCAO/SO₄^2- system due to the formation of SO₄^-, which reacted with CIP more slowly (8.4 × 10⁸ M^-1 s^-1) than OH (4.1 × 10⁹ M^-1 s^-1). In MCAO/SO₄^2-/Cl^- mixture saline conditions, mineralization of CIP was improved at low Cl^- concentration (0.5 wt%) due to the generation of Cl, while inhibited with excessive Cl^- (≥1.5 wt%) owing to the formation of residual chlorides (Cl₂, Cl₂^- and ClO^-). Meanwhile, the MCAO process possessed promising capability to remediate hypersaline wastewater containing dyes, phenol and pesticides, as well as actual salinity-rich wastewater. Based on the above, the present study would provide new insights into hypersaline organic wastewater treatment by the MCAO process.

Adsorption and catalytic degradation of organic contaminants by biochar: Overlooked role of biochar's particle size

Biochar (BC) is considered as a promising adsorbent and/or catalyst for the removal of organic contaminants. However, the relationship between the particle size of BC and its adsorption/catalysis performance is largely unclear. We therefore investigated the influence of particle size on the performance of BC pyrolyzed at 300-900 °C in trichloroethylene (TCE) adsorption and persulfate (PS) activation for sulfamethazine (SMT) degradation. The results showed that high-temperature pyrolyzed BC (BC900) presented superior adsorption capacity for TCE and excellent catalytic activity for PS activation to degrade SMT. Compared to 150-250 µm, 75-150 µm and pristine BC900, 0-75 µm BC900 showed the highest TCE adsorption efficiency, which increased by 19.5-62.3%. Similarly, SMT removal by BC900/PS systems also increased from 24.2% to 98.3% with decreasing BC particle size. However, the catalytic activity of BC after grinding was not significantly improved as expected, indicating the properties of biochar was not only controlled by size effect. Characterization measurements proved that small-sized BC tended to have larger specific surface area, more micropores, higher conductivity, rich graphitic domains and surface redox-active functional groups, thus resulting in an enhanced adsorption and catalytic ability of BC.

The performance and pathway of indole degradation by ionizing radiation

Indole is a typical recalcitrant aromatic nitrogen heterocyclic compound, which usually exists in coal chemical wastewater, and cannot be effectively removed by conventional wastewater treatment process. In this study, ionizing radiation was applied for the degradation of indole in aqueous solution. The effect of absorbed dose (1, 2, 3 and 5 kGy), initial concentration of indole (10, 20, 40 and 100 mg/L) and pH (3, 5, 7 and 9) on the degradation of indole was investigated. The results showed that the removal efficiency of indole was 99.2% at its initial concentration of 10 mg/L, absorbed dose of 2 kGy, and pH of 5. In addition, quenching experiments confirmed that three reactive species, including hydroxyl radical, hydrated electron and hydrogen radical, contributed to indole degradation. Five intermediate products were identified during indole degradation, including 3-methylindole, 3-methylinodle radicals, hydroxylation inodole, anilinoethanol and isatoic acid. The possible pathway of indole degradation was proposed. The acute toxicity and chronic toxicity of intermediate products of indole degradation were significantly reduced, except for 3-methylindole. In summary, ionizing radiation is alternative technology for the degradation of indole in coal chemical wastewater.

Degradation of chloroaniline in chemical wastewater by ionizing radiation technology: Degradation mechanism and toxicity evaluation

Chloroaniline is a typical organic pollutant in chemical wastewater, which cannot be effectively removed in conventional wastewater treatment processes. In this study, ionizing radiation was used as advanced treatment process to degrade 2-chloroaniline (2-CA). The results showed that 10 mg/l of 2-CA could be completely degraded at 1 kGy. The required dose for completely degrading 2-CA by radiation increased when its initial concentration increased. Solution pH affected 2-CA degradation by changing the radiation-chemical yield of reactive species. Chloride ions (10 and 100 mM) had not obvious influence on 2-CA degradation. Hydrogen radicals, hydrated electrons and hydroxyl radicals, all contributed to the degradation of 2-CA, but with different degradation mechanisms. Hydrogen radicals and hydrated electrons could initiate reductive dechlorination of 2-CA, while hydroxyl radicals can degrade 2-CA by hydroxylation. 6-amino-1,4-cyclohexadiene and chlorobenzene were the main intermediate products of 2-CA degradation in the hydrogen radicals or hydrated electrons dominant process; while o-hydroxyaniline and nitroso-chlorobenzene were the main intermediate products in the hydroxyl radicals dominant process. The solution toxicity after radiation treatment varied with the initial concentration of 2-CA and the absorbed dose. In the actual chemical wastewater, 2-CA can be effectively removed by radiation, even in the presence of high concentration of chloride ions (about 2800 mg/l). The solution toxicity of actual wastewater decreased with the increase of adsorbed dose. This study provided an insight into the 2-CA degradation by radiation, and demonstrated that radiation could be an alternative option for the treatment of chloroaniline-containing chemical wastewater.

Optimization of electrochemical activation of persulfate by BDD electrodes for rapid removal of sulfamethazine

Boron-doped diamond electrodes have been employed for the removal of sulfamethazine (SMZ) from water by electrochemical activation of persulfate (EO/BDD-PS). A set of experiments with a central composite design (CCD) was conducted to optimize the operating parameters such as persulfate dose, solution pH, and current density by response surface methodology (RSM). The experimental results indicated a rapid degradation of SMZ even at high initial concentrations. For instance, complete degradation of 50 mg L^-1 of SMZ was attained after 15 min at the optimum operating conditions (persulfate loading = 0.40 g L^-1, pH = 4, and current density = 21 mA cm^-2). The oxidation mechanism of EO/BDD-PS process was studied based on the reactive oxidant species (ROS) revealing that both (OH) and contributed to the degradation of SMZ in the EO/BDD-PS system. Furthermore, the oxidation pathway has been proposed by the suspect screening and tandem mass spectrometry analysis. The performance of EO/BDD-PS showed faster SMZ degradation than electro-Fenton and anodic oxidation processes using the same BDD electrochemical reactor under the same conditions. Furthermore, we provided a cost estimation study revealing that a full-scale application of the EO/BDD-PS system for the treatment of similar contaminated water costs about $2.23 m^-3.

Bifunctional iron molybdate as highly effective heterogeneous electro-Fenton catalyst and Li-ion battery anode

Three-dimensional materials have attracted considerable interest in energy and environmental remediation fields. Iron molybdate (FMO) materials have prepared via a facile hydrothermal technique with glycerol assistance, and their structural and chemical composition confirmed using various physico-chemical techniques. The prepared bi-functional material is a strong candidate for energy storage and electrocatalytic degradation of Methylene blue and Congo red. Experimental results confirmed the synthesized FMO-10 catalyst was extremely efficient for methylene blue and Congo red breakdown, achieving 91 % and 96 % degradation in 36 h, respectively. This high catalytic activity was attributed to FMO significant visible light absorption, and reactive OH formation from H₂O₂ synergistically triggered by both Fe³⁺ and MoO₄^2-. Prepared FMO samples demonstrated excellent potential as negative electrode material for lithium ion batteries. Electrode specific capacity initially dropped then rebounded to 1265 mAh g^-1 after 100 cycles at 100 mA g^-1 change rate between 0.01 and 3.0 V.

Preparation of magnetic urchin-like NiCo2O4 powders by hydrothermal synthesis for catalytic oxidative desulfurization

The bundle-like NiCo2O4 powder was synthesized using hydrothermal synthesis and high-temperature calcination method and, as catalyst, NiCo2O4 powder was utilized to activate peroxymonosulfate for removing dibenzothiophene from fuel oil.

Mechanism of catalytic ozonation for elimination of methyldopa with Fe3 O4 @SiO2 @CeO2 catalyst

In this study, a magnetic nanocatalyst (Fe₃ O₄ @SiO₂ @CeO₂ ) was prepared and applied in the catalytic ozonation of methyldopa (MD). The effects of operational parameters on catalytic ozonation performance were investigated, including ozone dosage, catalyst dosage, initial MD concentration, and pH. The removal of MD was 45.2% in ozonation, whereas the efficiency was achieved to 83.0% with the addition of Fe₃ O₄ @SiO₂ @CeO₂ . The results showed that Fe₃ O₄ @SiO₂ @CeO₂ could significantly improve the catalytic ozonation performance. And the enhanced mechanism study showed that it was attributed to promotion of ozone decomposition to generate hydroxyl radical. The reaction model was explored, and the reaction rates were calculated for the MD degradation in catalytic ozonation. A higher degradation efficiency of MD in catalytic ozonation was attributed to the enhanced surface effect of the catalysts, which was confirmed by using TBA, PO₄ ^3- , and p-BQ as scavengers of hydroxyl radical, surface reaction, and superoxide radical. The hydroxyl radical and superoxide radical played an important role in the degradation of MD. The mechanism of catalytic ozonation by Fe₃ O₄ @SiO₂ @CeO₂ was discussed via X-ray photoelectron spectroscopy (XPS) spectra and experimental data.

Cobalt-Enhanced Mass Transfer and Catalytic Production of Sulfate Radicals in MOF-Derived CeO2 • Co3 O4 Nanoflowers for Efficient Degradation of Antibiotics

Antibiotics discharge has been a critical issue as the abuse in clinical disease treatment and aquaculture industry. Advanced oxidation process (AOPs) is regarded as a promising approach to degrade organic pollutants from wastewater, however, the catalysts for AOPs always present low activities, and uncontrollable porosities, thus hindering their further wider applications. In this work, an aliovalent-substitution strategy is employed in metal-organic framework (MOF) precursors assembly, aiming to introduce Co(II/III) into Ce-O clusters which could modify the structure of the clusters, then change the crystallization, enlarge the surface area, and regulate the morphology. The introduction of Co(II/III) also enlarges the pore size for mass transfer and enriches the active sites for the production of sulfate radicals (SO₄^• - ) in MOF-derived catalysts, leading to excellent performance in antibiotics removal. Significantly, the CeO₂ •Co₃ O₄ nanoflowers could efficiently enhance the generation of sulfate radical SO₄^• - and promote the norfloxacin removal efficiency to 99% within 20 min. The CeO₂ •Co₃ O₄ nanoflowers also present remarkable universality toward various antibiotics and organic pollutants. The aliovalent-substitution strategy is anticipated to find wide use in the exploration of high-performance MOF-derived catalysts for various applications.

Fe-based Fenton-like catalysts for water treatment: Preparation, characterization and modification

Fenton reaction based on hydroxyl radicals () is effective for environment remediation. Nevertheless, the conventional Fenton reaction has several disadvantages, such as working at acidic pH, producing iron-containing sludge, and the difficulty in catalysts reuse. Fenton-like reaction using solid catalysts rather than Fe²⁺ has received increasing attention. To date, Fe-based catalysts have received increasing attention due to their earth abundance, good biocompatibility, comparatively low toxicity and ready availability, it is necessary to review the current status of Fenton-like catalysts. In this review, the recent advances in Fe-based Fenton-like catalysts were systematically analyzed and summarized. Firstly, the various preparation methods were introduced, including template-free methods (precipitation, sol gel, impregnation, hydrothermal, thermal, and others) and template-based methods (hard-templating method and soft-templating method); then, the characterization techniques for Fe-based catalysts were summarized, such as X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET), SEM (scanning electron microscopy)/TEM (transmission electron microscopy)/HRTEM (high-resolution TEM), FTIR (Fourier transform infrared spectroscopy)/Raman, XPS (X-ray photoelectron spectroscopy), ⁵⁷Fe Mössbauer spectroscopy etc.; thirdly, some important conventional Fe-based catalysts were introduced, including iron oxides and oxyhydroxides, zero-valent iron (ZVI) and iron disulfide and oxychloride; fourthly, the modification strategies of Fe-based catalysts were discussed, such as microstructure controlling, introduction of support materials, construction of core-shell structure and incorporation of new metal-containing component; Finally, concluding remarks were given and the future perspectives for further study were discussed. This review will provide important information to further advance the development and application of Fe-based catalysts for water treatment.

High mass loading flower-like MnO2 on NiCo2O4 deposited graphene/nickel foam as high-performance electrodes for asymmetric supercapacitors

The implementation of high mass loading MnO₂ on electrochemical electrodes of supercapacitors is currently challenging due to the poor electrical conductivity and elongated electron/ion transport distance. In this paper, a NiCo₂O₄/MnO₂ heterostructure was built on the surface of three-dimensional graphene/nickel foam (GNF) by a hydrothermal method. The petal structured NiCo₂O₄ loaded on graphene played a wonderful role as a supporting framework, which provided more space for the growth of high mass loading MnO₂ microflowers, thereby increasing the utilization rate of the active material MnO₂. The GNF@NiCo₂O₄/MnO₂ composite was used as a positive electrode and achieved a high areal capacitance of 1630.5 mF cm^-2 at 2 mA cm^-2 in the neutral Na₂SO₄ solution. The asymmetric supercapacitor assembled with the GNF@NiCo₂O₄/MnO₂ positive electrode and activated carbon negative electrode possessed a wide voltage window (2.1 V) and splendid energy density (45.9 Wh kg^-1), which was attributed to the satisfactory electroactive area, low resistance, quick mass diffusion and ion transport caused by high mass loading MnO₂.