Catalyst For Ozonation Research Articles

Enhancing Ibuprofen and 4-Isobutylacetophenone degradation: Exploiting the potential of Nb2O5 sol-gel catalysts in photocatalysis, catalytic ozonation, and photocatalytic ozonation

This study describes the synthesis of Nb2O5 by three sol-gel methods to be used as a catalyst in photocatalysis, catalytic ozonation and the synergistic effects of the two processes, photocatalytic ozonation in bath reactions for the degradation of ibuprofen and its degradation products, 4- Isobutylacetophenone and oxalic acid. The catalysts were prepared in three temperature ranges: non-calcined, calcined at 873 K and 1173 K, and were characterized using different techniques. The results demonstrate that the catalyst synthesized through Sol-gel Method 3 and heat-treated at 873 K achieved the highest pollutant removal in photocatalytic tests (92% with 95% TOC reduction) over 300 min of reaction, and in the catalytic ozonation tests (100% with 62% TOC reduction) over 30 min of reaction, due to the combination of the properties presented in the characterization analyzes. Thus, this catalyst was employed in photocatalytic ozonation reactions and demonstrated the capability to degrade 100% of ibuprofen in 12 min without 4-IBAP formation, resulting in a 98% reduction in TOC over 30 min of reaction. In addition, the photostability outcomes of this catalyst demonstrated no significant reduction in catalytic activity during the photocatalytic and catalytic ozonation processes and comparable results to P25. The toxicity tests validated the TOC results, showing an 8% effect vs. 90% of ibuprofen starting solution, and 43% effect vs. 95% of 4-IBAP starting solution.

Enhanced catalytic ozonation performance by CuOx nanoclusters/TiO2 nanotube and an insight into the catalytic mechanism

Highly reactive nanoclusters of metal oxides are extremely difficult to be synthesized due to their thermodynamic instability. For the first time, CuOx nanoclusters supported on anatase TiO2 nanotubes (NT) with many defects as anchoring sites were successfully prepared. Although the copper loading reached as high as 2.5 %, the size of CuOx nanoclusters in the sample of 2.5 %CuOx/NT were mainly around 1.0 nm. The aggregation of copper species during the calcination process was undoubtedly hampered by the anchoring effects of the abundant defects in NT support. Due to the highly exposed undercoordinated atoms of CuOx nanoclusters, the mixed valences of copper, and the strong interface interaction between CuOx nanoclusters and NT support, 2.5 %CuOx/NT-catalyzed ozonation showed the highest pseudo-first-order reaction rate constant of 8.5 × 10−2 min−1, 2.2 and 4.0 times that of NT-catalyzed ozonation and ozonation alone, respectively. Finally, the catalytic mechanism was revealed by both experiments and density functional theory calculations (DFT). The results demonstrated that the undercoordinated Cu in CuOx/NT could highly promote the adsorption of ozone with a high adsorption energy of −125.16 eV and the adsorbed ozone was activated immediately, tending to dissociate into a O2 molecule and a surface O atom. Thus, abundant reactive oxygen species, e.g., hydroxyl radical (·OH), superoxide radical (·O2–) and singlet oxygen (1O2), could be generated via chain reactions. Especially, ·OH mainly contributed to the removal of ibuprofen pollutants. This work sheds a light on the design and preparation of highly reactive nanoclusters of metal oxide catalysts for catalytic ozonation of refractory organic pollutants.

Magnetic nanohybrid derived from MIL-53(Fe) as an efficient catalyst for catalytic ozonation of cefixime and process optimization by optimal design

The catalytic activity of metal-organic frameworks (MOFs) in the degradation of environmental pollutants has garnered considerable interest recently. FTIR, FE-SEM, EDS, XRD, XPS, VSM, TEM, and N2 sorption-desorption isotherms were used to characterize Fe-based nanohybrids derived from MIL-53(Fe). In the catalytic ozonation of cefixime (CFX), the nanohybrid (CM-500) synthesized at 500 °C exhibited high efficiency. The enhanced catalytic activity of CM-500 may have been caused by Lewis acid sites (LAS), iron oxides, and oxygenated functional groups of the mesoporous carbon substrate that remained after pyrolysis of the organic framework. During 15 min of continuous ozonation, the CM-500/O3 process was the most effective at removing CFX with a removal efficiency of 97%, significantly higher than single ozonation with a degradation efficiency of 43% under the same conditions. Modeling and optimization of process conditions were conducted using a novel and efficient class of experimental design, namely optimal design with the fewest possible runs. Calculated CFX degradation kinetic rate constants were 0.212 min-1 with CM-500, 0.043 min-1 with MIL-53 (Fe), and 0.038 min-1 for ozonation alone. Mineralization (measured COD and TOC) is significantly higher in the CM-500/O3 system compared to single ozonation. Moreover, the scavenging experiment confirmed that the reactive oxygen species in the catalytic ozonation of CFX are surface-adsorbed superoxide and hydroxyl radicals. Due to CM-500's sustained activity and magnetic properties, it is expected that it has a high catalytic capacity for treating pharmaceutical wastewater.

The efficiency and mechanism of excess sludge-based biochar catalyst in catalytic ozonation of landfill leachate

In this study, biochar was produced based on dehydrated excess sludge from the municipal wastewater treatment plant, which was used for catalytic ozonation of pollutants derived from landfill leachate. The necessary catalytic sites in the structure of biochar were originated from the inorganic metals and organic matters in the sludge, which included a large number of functional groups (e.g., C-C, CO, etc.), adsorbed oxygen (Oads accounted for 44.82%) and electron defects (ID/IG=1.01). These active sites could promote the generation of reactive oxygen species (ROS) (e.g., ·OH,·O2-, etc.). The synergistic interaction between the microorganisms in the activated sludge also facilitated the removal rates of pollutants. Proteobacteria, Bacteroidetes, and Deinococcu-Thermus were crucial in the bioreactor. In 16 days of reaction, the removal ratios of NH+4-N and COD were 98.95 ± 0.11% and 90.89 ± 0.47%, respectively. This study not only explains the mechanism of catalytic ozonation of biochar, but also provides a new way of the practical treatment of landfill leachate.

Cation Substitution Induced d‐Band Center Modulation on Cobalt‐Based Spinel Oxides for Catalytic Ozonation

AbstractCo3O4 spinel is a promising transition metal oxide (TMO) catalyst for the catalytic ozonation of volatile organic compounds (VOCs). Herein, metal–organic frameworks (MOFs)‐derived Ni‐ and Mg‐ substituted Co3O4 catalysts retain similar spinel structures, but display improved and reduced ozonation performance of methyl mercaptan (CH3SH), respectively. Remarkably, the NiCo2O4 catalyst can still ≈90% removal of CH3SH after running for 20 h at room temperature under an initial concentration of 50 ppm CH3SH and 40 ppm O3, relative humidity of 60%, and space velocity of 300 000 mL h−1 g−1, exceeding the reported values. Experimental characterizations have unveiled that the substitution of Ni and Mg into the Co3O4 spinel altered surface acidity, oxygen species mobility, and Co2+/Co3+ ratio. The in situ Raman spectra reveal the dynamic formation Co(III)‐Oad* via the transformation of O3 into surface atomic oxygen (Oad*) and peroxide species (O2*). Theoretical calculations verify that Ni‐substitution increases nonuniform charges and Fermi density, leading to a moderate increase in d‐band center energy levels, thereby promoting O3 specific adsorption/activation to convert Oad*/O2* and •OH/1O2/•O2−, which contributes to eliminate CH3SH and prevent poisoning. The concept of tuning the d‐band center can provide valuable insights for the design of other catalysts for catalytic ozonation.

Catalytic Ozonation of Pesticide Wastewater by Using MCM-41 and ZSM-5/MCM-41 as Catalysts

In the present study, two catalysts, MCM-41 and ZSM-5/MCM-41, were prepared by the hydrothermal synthesis method and their catalytic ozonation performances on pesticide wastewater were investigated. MCM-41 and ZSM-5/MCM-41 were proved to be a mesoporous structure and a micro-mesoporous structure, respectively, by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption measurements. The experimental results indicated that the chemical oxygen demand (COD) removal rate increased from 57.46% without catalysts to 79.35% and 87.56%, respectively, in the presence of MCM-41 and ZSM-5/MCM-41 after 100 min of catalytic ozonation. The catalytic activity of ZSM-5/MCM-41 was found to be greater than that of MCM-41. OH· played an important role in the catalytic ozonation, which was verified by the tert-butanol test. The catalysts had highest activity at pH of 7, and both higher and lower pH values reduced the catalytic ozonation. The optimal ozone dosage was found to be 22.0 mg L−1 min−1 for the COD removal of the pesticide wastewater. The catalysts could be reused five times without significant loss of the catalytic activity, suggesting that the catalysts could be promising catalysts for the catalytic ozonation of the pesticide wastewater.

Nanographite: A highly active and durable metal-free ozonation catalyst with application in natural waters

The development of metal-free heterogeneous catalysts for advanced oxidation processes has emerged as a key focus for both academia and industry. We report on research that seeks to establish a correlation between the crystallographic, physicochemical, textural, and morphological properties of a series of graphite-based solids and their activities as metal-free ozonation catalysts in aqueous media. Our findings show that nanographite (NG) outperforms traditional graphite-based solids, activated carbon and Co3O4. The enhanced activity of NG is due to defective nanosized graphitic structures with high surface areas. NG exhibits an exceptional activity, durability, and recyclability that surpasses other known catalysts. Our study employs electron spin resonance and selective quenching experiments that reveal the generation of 1O2 during catalytic ozonation. Significantly, NG shows excellent catalytic efficiency even when using natural surface river water or seawater. This study illustrates the importance of the natural properties of graphite-based materials as active and durable ozonation catalysts in water.

PPCPs abatement using TiO2-based catalysts by photocatalytic oxidation and ozonation: The effect of nitrogen and cerium loads on the degradation performance and toxicity impact

Pharmaceutical and personal care products (PPCPs) have been consumed in great extension and most of these are found in water bodies, owing to the inefficiency of conventional wastewater treatments. To face against these recalcitrant contaminants, advanced oxidation processes such as photocatalysis and ozonation have been studied. Moreover, the combination of these technologies can improve the degradation of PPCPs, reducing the ozone consumption and the effluent toxicity with the presence of photocatalysts. In particular, this study aimed to evaluate the effects of different N and Ce loads in co-doping TiO2 catalysts on the efficiency of photocatalytic oxidation and photocatalytic ozonation for PPCPs abatement, as well as on the resultant toxicity to aquatic species. Different radiation sources (UVA and solar radiation) were considered for the photocatalytic oxidation. A mixture of 5 PPCPs: paracetamol, sulfamethoxazole, carbamazepine, methylparaben and propylparaben was used as a model synthetic effluent. Photocatalysis showed a low efficiency on the PPCPs removal (<20 %), which was not affected by the radiation source. In general, the tested catalysts showed no or low added-value for reducing the toxicity of the synthetic effluent. Concerning photocatalytic ozonation, the lowest N amount (2.5 % w/w) promoted the best results for PPCPs removal, achieving values up to 100 % with significant reduction of ozone dose compared to photolytic ozonation. In general, photocatalytic ozonation showed better ecotoxicological performance than single photocatalysis. Compared to single photolytic ozonation, a benefitial effect was observed for two aquatic species, using a specific catalyst. This catalyst, prepared by doping TiO2 with 2.5 % w/w N and 1.2 % w/w Ce, showed to be the most promisong one, with potential to be used in photocatalytic ozonation. Hence, this work highlights the potential role of N and Ce co-doped TiO2-based catalysts in photocatalytic ozonation for wastewater treatment.

The special mechanisms of quasi-complexation and enhanced effect of “·OH action zone” in activated carbon combined ozonation

Activated carbon (AC) is an excellent adsorbent and is widely employed as a catalyst in catalytic ozonation. However, the massive change in surface oxygen groups on AC before and after ozonation in this research indicated that AC was not a real catalyst. Moreover, the lower oxalic acid removal effect and the observed hydroxyl radicals (·OH) accumulative amount of pre-oxidative AC combined ozonation confirmed that AC functioned as an activator. We investigated the removal trend of oxalic acid in AC-activated ozonation under different pH, and it was consistent with its adsorption via adjusting the oxalic acid adsorbed on AC. Despite the accumulation concentration of ·OH reaching the highest value at pH = 4.7, the activated ozonation did not perform best. Considering the extremely short life of ·OH in an aqueous solution, an “action zone” existed, which was the effective region for ·OH to react with organics. This result proved that the AC adsorption would concentrate organics in the “action zone”, thus improving the degradation of organic contaminants. The solution containing oxalic acid had a higher accumulative concentration of ·OH than without oxalic acid, which meant a previously neglected pathway existed to produce ·OH. In addition, C2O4·- was reported in the solution containing AC, oxalic acid, and oxygen. Thus, the quasi-complexation reaction might occur between AC, oxalic acid, and oxygen. Overall, this study disclosed distinct mechanisms due to AC adsorption in the AC combined ozonation system.

Effect of the deposition of Ca2+on the Fe-based catalyst in the catalytic ozonation of high-salinity wastewater

Fe-based catalysts used for catalytic ozonation process (COP) were widely investigated. However, there was almost no research on engineering application of Fe-based catalyst for advanced treatment of high-salinity pharmaceutical wastewater. In this study, Fe shavings were used to form Fe-based monolithic catalyst packing, which was effectively applied to a pharmaceutical factory. It was found that chemical oxygen demand (COD) removal decreased by ∼ 20% after more than three years of operations. Regression analysis showed that ozone (O3) dosage and hydraulic residence time (HRT) had significant impact on the catalytic performance. The characterization results of Fe-based catalyst demonstrated that calcium carbonate (CaCO3) was deposited on the surface of the Fe-based catalyst inside the packing, and partial γ-FeOOH were converted into α-FeOOH. These phenomena impaired the catalytic capacity of Fe-based catalyst and further reduced the production of hydroxyl radicals (OH). Besides, the increase in bulk density of Fe-based monolithic catalyst packing indicated that the packing has collapsed. By comparing the surface film properties of Fe-based catalyst in wastewater with different salinity, it was concluded that high-salinity wastewater would accelerate the corrosion of Fe-based catalyst. This study can provide a reference for the engineering application of catalytic ozonation technology in high-salinity wastewater.

Degradation of Sulfoxaflor Pesticide in Aqueous Solutions Utilizing Photocatalytic Ozonation with the Simultaneous Use of Titanium Dioxide and Iron Zeolite Catalysts

Water pollution is a globally recognized serious problem that is hindering human development and societal progress. One of the most feasible methods to eliminate this problem is wastewater treatment and reuse. Emerging micropollutants, such as pesticides, are notorious for not being removed using traditional treatment methods. Therefore, novel techniques such as advanced oxidation processes (AOPs) have been proposed, among which photocatalytic ozonation is arguably the best option. Sulfoxaflor belongs to a relatively newer class of compounds known as sulfoximines and has not been studied for degradation using photocatalytic ozonation. In this work, we explore the degradation of sulfoxaflor, specifically a Dow product containing sulfoxaflor as an active ingredient using various AOPs, particularly photocatalytic ozonation. Photocatalytic ozonation has shown a synergy of 2.23 times compared to photocatalysis and ozonation alone. Fe-zeolite can improve the treatment time as an ozonation catalyst, reducing the removal time from 22 min to 18 min while reducing the electrical energy per order and electrical energy per order (EEO) from 69.5 to 42.92 kWh m−3 order−1. Catalysts have been characterized using scanning electron microscopy and point of zero charge. The effects of the initial concentration, UV intensity, catalyst dose, and catalyst reuse have been studied. Moreover, the rate constants have been determined using curve fitting, and the mechanism is proposed.

Hydrothermally improved natural manganese-containing catalytic materials to degrade 4-chlorophenol

Natural manganese-containing mineral (NMM) was used as a catalyst in heterogeneous catalytic ozonation for 4-chlorophenol (4-CP) degradation. The surface and structural properties of NMM were modified by the hydrothermal aging process and called H-NMM. The catalytic activity of NMM and H-NMM were evaluated for the catalytic ozonation process (COP). The synergistic effect of NMM and H-NMM in ozonation processes for 4-CP degradation under optimal conditions (pH of 7, 1 g/L of NMM and H-NMM, 0.85 mg/min of O3, and 15 min of reaction time) was measured by 3.04 and 4.34, respectively. During the hydrothermal process, Mn4+ and Fe2+ were converted to Mn2+ and Fe3+, which caused better performance of the H-NMM than the NMM. During the catalytic ozonation process, Mn2+ is completely oxidized, which increases the production of Hydroxyl radical (•OH). The reactive oxygen species (ROS) generated in the system were identified using radical scavenging experiments. •OH, superoxide radical (•O2−), and singlet oxygen (1O2) represented the dominant reactive species for 4-CP degradation. The O3/H-NMM process indicated a powerful ability in the mineralization of 4-CP (66.31% of TOC degradation). H-NMM exhibited excellent stability and reusability in consecutive catalytic cycles, and the NMM exhibited desirable performance. This study offers NMM and H-NMM as effective, stable, and competitive catalysts for hastening and enhancing the ozonation process to mitigate environmentally related pollutants of high concern.

Magnetic nano-size normal spinel-ZnFe2O4 and inverse spinel-MnFe2O4 for catalytic ozonation: Performance and mechanism

Spinel nanomaterials, as magnetic catalysts for catalytic ozonation, have gradually attracted the attention of researchers due to the easy-to-separate and recyclable properties. However, few studies have systematically studied the catalytic mechanism. Hence, normal spinel-ZnFe2O4 and inverse spinel-MnFe2O4 were prepared and applied to catalyze the ozonation of oxalic acid (OA) and phenol in this study. ZnFe2O4 and MnFe2O4 showed opposite catalytic abilities: MnFe2O4 performed better than ZnFe2O4 in OA decomposition and the TOC (total organic carbon) removal efficiency reached 92.1%; ZnFe2O4 performed better than MnFe2O4 in phenol decomposition and the TOC removal efficiency reached 60.3%. Radical quantitative results showed •OH and •O2– were the main radicals with MnFe2O4 during the catalytic ozonation, and •OH was the main radical for the ZnFe2O4. DFT (density functional theory) calculation and catalysts characterization indicated a smaller band gap endowed MnFe2O4 with higher electron transport capacity than ZnFe2O4, which catalyze ozone decomposition into •O2–; ZnFe2O4 possessed more abundant surface hydroxyl groups than MnFe2O4, which catalyze ozone decomposition into •OH. Conclusively, this study systematically revealed the different catalytic mechanisms of normal spinel-ZnFe2O4 and inverse spinel-MnFe2O4, and showed a positive effect on the application of spinel catalysts.

Application of green and red local soils as a catalyst for catalytic ozonation of fulvic acid: experimental parameters and kinetic

Application of green and red local soils as a catalyst for catalytic ozonation of fulvic acid: experimental parameters and kinetic

A tailored and rapid approach for ozonation catalyst design

Catalytic ozonation is widely employed in advanced wastewater treatment owing to its high mineralization of refractory organics. The key to high mineralization is the compatibility between catalyst formulation and wastewater quality. Machine learning can greatly improve experimental efficiency, while fluorescence data can provide additional wastewater quality information on the composition and concentration of organics, which is conducive to optimizing catalyst formulation. In this study, machine learning combined with fluorescence spectroscopy was applied to develop ozonation catalysts (Mn/γ-Al2O3 catalyst was used as an example). Based on the data collected from 52 different catalysts, a machine-learning model was established to predict catalyst performance. The correlation coefficient between the experimental and model-predicted values was 0.9659, demonstrating the robustness and good generalization ability of the model. The range of the catalyst formulations was preliminarily screened by fluorescence spectroscopy. When the wastewater was dominated by tryptophan-like and soluble microbial products, the impregnation concentration and time of Mn(NO3)2 were less than 0.3 mol L−1 and 10 h, respectively. Furthermore, the optimized Mn/γ-Al2O3 formulation obtained by the model was impregnation with 0.155 mol L−1 Mn(NO3)2 solution for 8.5 h and calcination at 600 °C for 3.5 h. The model-predicted and experimental values for total organic carbon removal were 54.48% and 53.96%, respectively. Finally, the improved catalytic performance was attributed to the synergistic effect of oxidation (•OH and 1O2) and the Mn/γ-Al2O3 catalyst. This study provides a rapid approach to catalyst design based on the characteristics of wastewater quality using machine learning combined with fluorescence spectroscopy.

Catalytic ozonation of ketoprofen by defective boron nitride

This study focuses on the feasibility of boron nitride as a catalyst for ozonation of ketoprofen. The defective boron nitride was prepared by calcination of boric acid and melamine and characterized by XRD, SEM, FT-IR, XPS, temperature programmed desorption, Raman and UV–Vis diffuse reflectance spectra. The apparent rate constant and removal efficiency of chemical oxygen demand in the boron nitride catalyzed system were 2.7 times and 1.6 times higher than those of the ozonation alone at the pH of 7, respectively. The catalytic active sites were found to be acidic BOH and could be generated by manufacturing defects during preparation.

Effective Toluene Ozonation over δ-MnO2: Oxygen Vacancy-Induced Reactive Oxygen Species.

To improve the reactivity and lifetime of catalysts in the catalytic ozonation of toluene, a simple strategy was provided to regulate the morphology and microstructure of δ-MnO2 via the hydrothermal reaction temperature. The effects of the reaction temperature and the ozone to toluene concentration ratio on the catalyst performance were investigated. The optimized MnO2-260 catalyst prepared at the limiting hydrothermal temperature (260 °C) showed high catalytic activity (XTol = 95%) and excellent stability (1200 min) at the approximately ambient temperature of 40 °C, which was superior to the results in previous studies. The structure and morphology of δ-MnO2 were characterized by extended X-ray absorption fine structure, X-ray diffraction, scanning electron microscopy, positron annihilation lifetime spectroscopy, electron spin resonance, and other techniques. Experimental results and density functional theory calculations were in agreement that surface oxygen vacancy clusters, especially surface oxygen dimer vacancies, are critical in ozone activation. Oxygen vacancies can facilitate the adsorption and activation of O3 to generate reactive oxygen species (ROS, including 1O2, O2-, and •OH), leading to superior ozonation activity to degrade toluene and intermediates. Meanwhile, free radical detection and scavenger tests indicated that •OH is the primary ROS during toluene ozonation rather than 1O2 or O2-.

Copper Foam-Supported CuxO@Fe2O3 Core–Shell Nanotubes: An Efficient Ozonation Catalyst for Degradation of Organic Pollutants

Copper foam (CF)-supported CuxO@Fe2O3 core–shell nanotubes (CF/CuxO@Fe2O3 NTs) were synthesized as a hybrid catalyst for heterogeneous catalytic ozonation (HCO). The hybrid catalyst exhibits high activity and excellent stability for the HCO of organic pollutants. The total organic carbon removal rates of methyl orange, ibuprofen, and nitrobenzene via HCO were 89, 82, and 88%, respectively, which are over 2 times higher than the corresponding values obtained without the catalyst. The hybrid catalyst also displays wide pH operation range, low metal leaching, easy separation from treated water, and excellent recyclability. We prove that large amounts of Lewis acid sites with medium acidity are created at the CuxO/Fe2O3 interface due to the synergic effect of CuxO and Fe2O3. These medium acid sites are the main active centers for the production of free hydroxyl radicals (•OH) and superoxide radicals (O2•– or HO2•) in neutral solution. Moreover, the 3D porous framework of the catalyst enables easy dispersion in and separation from water. This work develops a new strategy to design HCO catalysts by combining strong and weak Lewis acid oxides and also opens a new avenue for developing HCO catalysts on a 3D porous framework.

Electron transfer enhancing the Mn(II)/Mn(III) cycle in MnO/CN towards catalytic ozonation of atrazine via a synergistic effect between MnO and CN

In this study, manganese oxide (MnO) dispersed on CN (Mn-nCN) was fabricated as a catalyst in heterogeneous catalytic ozonation (HCO), achieving excellent catalytic performance on refractory organic pollutant degradation via the synergistic effects between MnO and CN. The study demonstrated that the C–N−Mn and C−O−Mn bonds constructed in the catalyst linking MnO and CN created the synergistic effects which could overcome typical problems, such as metal leaching etc. The C−N−Mn and C−O−Mn bonds could promote electron transfer from cation-π reactions to form electron-rich Mn(II) sites and electron-poor CN sites. The electron-rich Mn(II) sites as active sites supplied electrons to ozone which then further evolved into reactive oxygen species (ROS). The electron-poor CN sites captured electrons from the pollutant intermediate radicals to electron-rich Mn(II) sites via cation-π reactions with the help of C−N−Mn and C−O−Mn bonds, which promote the redox reactions of Mn. The surface hydroxyl groups also participated in ozone decomposition and ROS production. Additionally, •OH was the dominant ROS of the Mn-nCN HCO processes. This study presents the excellent HCO performance of Mn-nCN, as well as provides views on the electron transfer route between the catalyst, pollutant and ozone, which is crucial for the design of the catalyst.

A novel hybrid treatment for pharmaceutical wastewater implying electroflocculation, catalytic ozonation with Ni-Co Zeolite 5A° catalyst followed by ceramic membrane filtration

The removal of veterinary antibiotics in pharmaceutical wastewaters become more challenging with modern-day technologies due to their persistent nature. In a sequence, the release of veterinary antibiotics containing wastewater such as Enrofloxacin (EFC) and Tylosin Tartrate (TT) in water bodies has increased the chance for bacteria to attain the antibiotic resistance genes and also moved to others via horizontal gene movement. As a result, the microbes become more resistant even to conventional antibiotics due to the growth of antibiotic resistance genes in microbes. Consequently, conventional treatment technologies just partially remove the pharmaceuticals from the wastewater and are not fully effective because they are not premeditated to remove antibiotics drugs. This alarming situation seriously threatens human well-being and aquatic life. Therefore, it is indeed important to develop an economical advanced oxidation treatment method for the efficacious treatment of pharmaceutical wastewater (PhWW). In the current study, a novel approach was adopted by implying Electroflocculation (EF), Catalytic ozonation (CO) in combination with novel catalyst Ni-Co-Zeolite 5A° followed by Ceramic membrane filtration (CMF). For the first time, in the current investigation, the studied hybrid process (EF + CO–CMF) using Zeolite 5A° coated with double metal salts of Nickel and Cobalt was applied as a catalyst in ozonation (O3) for the treatment of PhWW. Moreover, the removal of COD, BOD5, and turbidity was also studied and compared with national and international effluent quantity discharge standards. The obtained results exhibited that the combined EF + CO process has achieved removal efficiencies of 33 %, 93 %, 78 %, 45 %, and 60 % for EFC, TT, COD, BOD5, and turbidity respectively. Furthermore, the integration of CMF after EF + CO has enhanced the removal of pollutants up to the mark. It was revealed that the novel combined treatment method EF + Ni-Co Zeolite 5A°/O3–CMF has removed the EFC, TT, COD, BOD5, and turbidity of 97 %, 98 %, 90 %, 86 %, and 93 % respectively at optimum conditions (pH = 7.1 ± 0.2; treatment time = 30 min; EF voltage = 10 V; catalyst dose = 10 g/L; O3 = 1.1 mg/min). Additionally, it was observed that biodegradability (BOD5/COD ratios) enhanced from 0.48 to 0.60, and become easily biodegradable for further treatment. Henceforth, EF + Ni-Co Zeolite 5A°/O3–CMF treated wastewater has also complied with the Punjab Environmental Quality Standards (PEQS). Therefore, this novel hybrid treatment process may efficaciously apply at an industrial scale for the treatment of veterinary antibiotics containing PhWW.