Ozone Flow Rate Research Articles

Ceramic membrane ozonator for soluble organics removal from produced water

In this work, the performance of ozonation for degradation of soluble organic compounds in produced water was investigated. Tubular ceramic membrane diffuser (with and without a static mixer in the lumen side) was used to facilitate contact between ozone and produced water. The ozonation was conducted at ozone flow rate of 8 L.min-1, ozone concentration of 0.4 ppm, original pH of the solution, and pressure of 1.2 bar, while the flow rates of the produced water were varied (192, 378 and 830 mL.min-1). It was found that the reduction of benzene, toluene, ethylbenzene, and xylene were 85%, 99%, 85%, and 95%, respectively. A lower liquid flow rate in a laminar state showed a better component reduction due to the longer contacting time between the liquid and the gas phase. The introduction of the static mixer in the lumen side of the membrane as a turbulence promoter provided a positive effect on the performance of the membrane diffuser. The twisted static mixer exhibited the better removal rate than the spiral static mixer.

Catalytic ozonation of succinic acid in aqueous solution using the catalyst of Ni/Al2O3 prepared by electroless plating-calcination method

Abstract A catalyst of the Ni/Al2O3 was prepared by electroless plating-calcination (EPC) method using Al2O3 support for catalytic ozonation. To evaluate the catalytic activity of Ni/Al2O3, the O3 + Ni/Al2O3 system was set up to degrade succinic acid (SA). First, the key preparation parameters (i.e., plating time, calcination temperature and calcination time) of Ni/Al2O3 and operational parameters (i.e., initial pH, ozone flow rate and the catalyst dosage) of O3 + Ni/Al2O3 system were optimized, respectively. The maximum SA removal (100%) and total organic carbon (TOC) removal (84.7%) were obtained under the optimal conditions. Meanwhile, characteristics of the Ni/Al2O3 catalysts prepared by EPC method and traditional impregnation-calcination (IC) method were studied comparatively through scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Brunauer-Emmet-Teller (BET), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The results show that nickel oxides (NiO) was uniformly deposited on the Al2O3 surface when Ni/Al2O3 was prepared by EPC method. On the contrary, when Ni/Al2O3 was prepared by IC method, nickel oxides were heterogeneously, rough and loose distributed on the surface of Al2O3 substrate. Furthermore, Ni/Al2O3 prepared by EPC possessed higher BET surface areas, higher pore volumes and smaller pore size distribution than Ni/Al2O3 prepared by IC. Finally, the catalytic mechanism of the O3 + Ni/Al2O3 system was proposed according to the characterization of Ni/Al2O3 prepared by EPC, radical scavenging studies, hydroxyl radical (HO ) and H2O2 detection experiments. Collectively, these results suggest that the EPC method was a promising technology for catalyst preparation of Ni/Al2O3 with high catalytic performance and the Ni/Al2O3 should be proposed as a promising catalyst for the decomposition of ozone.

Treatment of textile dyeing industry effluent using hydrodynamic cavitation in combination with advanced oxidation reagents

Treatment of textile dyeing industry (TDI) effluent was investigated using hydrodynamic cavitation (HC) and in combination with advanced oxidation reagents such as air, oxygen, ozone and Fenton’s reagent. Slit venturi was used as the cavitating device in HC reactor. The effects of process parameters such as inlet pressure, cavitation number, effluent concentration, ozone and oxygen flow rate, loading of H2O2 and Fenton’s reagent on the extent of reduction of TOC, COD and color were studied. Efficiency of the hybrid treatment processes were evaluated on the basis of their synergetic coefficient. It was observed that almost 17% TOC, 12% COD, and 25% color removal was obtained using HC alone at inlet pressure of 5bar and pH of 6.8. The rate of reduction of TOC and COD decreased with dilution of the samples. HC in combination with Fenton’s reagent (FeSO4·7H2O:H2O2 as 1:5) was most effective with reduction of 48%TOC and 38% COD in 15min and 120min respectively with almost complete decolorization (98%) of the TDI effluent. Whereas HC in combination with oxygen (2L/min) and ozone (3g/h) produced reduction of 48% TOC, 33% COD, 62% decolorization and 48% TOC, 23% COD, 88%, decolorization of TDI effluent respectively.

Photocatalytic degradation of Acid Blue 80 using iron doped TiO2 catalyst: Understanding the effect of operating parameters and combinations for synergism

The present work deals with the application of iron doped TiO2 catalyst (loading of 0.4 mol%) synthesized using novel ultrasound assisted approach in the photocatalytic degradation of Acid Blue 80 dye. The focus of the work is on understanding the effect of various parameters such as catalyst loading, UV power and using sunlight as alternative to UV as well as using H2O2, ozone, potassium persulfate (KPS) and ultrasound as process intensifying combinations for maximizing the extent of degradation. It has been established that 0.2g/L as the catalyst loading, use of catalyst obtained using the ultrasound assisted approach and UV power of 16W are the optimum conditions for individual operation of photocatalytic oxidation. For the combination of UV with H2O2, studies with different loading of H2O2 revealed that an optimum H2O2 loading of 10ppm resulted in maximum of 82.53% of degradation. Studies with different ozone flow rates established that an optimum ozone flow rate of 1L/min resulted in degradation of 55.07% and 56.09% for the approaches of only ozone and combination of ozone with UV light respectively. Studies for combination with KPS revealed that an optimum KPS loading of 0.4g/L resulted in a maximum degradation (99.59%) among all the approaches also yielding a COD reduction of 95%. Integral method of analysis was performed and it was observed that pseudo-first order kinetics explained the degradation very well. Overall it can be established that ultrasound plays an important role in giving the better catalyst and also combination approach of UV with KPS is the best treatment approach.

Hybrid treatment strategies for 2,4,6-trichlorophenol degradation based on combination of hydrodynamic cavitation and AOPs

Utilization of hybrid treatment schemes involving advanced oxidation processes and hydrodynamic cavitation in the wastewater treatment forms the prime focus of the present work. The initial phase of the work includes analysis of recent literature relating to the performance of combined approach based on hydrodynamic cavitation (HC) for degradation of different pollutants followed by a detailed investigation into degradation of 2,4,6-trichlorophenol (2,4,6-TCP). The degradation of the priority pollutant, 2,4,6-TCP, using combination of HC based on slit-venturi used as the cavitating device, ozone and H2O2 has been investigated. The effect of operating pressure (2–5bar) and initial pH (3−11) have been investigated for the degradation using only HC. The degradation using only ozone (100–400mg/h) and only H2O2 has also been studied. The efficacy of the combined operation of HC+O3 at different ozone flow rates (100–400mg/h) and the combined operation of HC+H2O2 at different loadings of H2O2 (2,4,6-TCP:H2O2 as 1:1–1:7) have been subsequently investigated. The degradation efficacy has also been established for the combined treatment strategies of O3+H2O2 and HC+O3+H2O2 at the optimum conditions of temperature as 30°C, inlet pressure of 4bar and initial pH of 7. Extent of 2,4,6-TCP degradation, TOC and COD removal obtained for HC+O3 process were 97.1%, 94.4% and 78.5% respectively whereas for O3+H2O2 process, the values were 95.5%, 94.8% and 76.2% and for HC+O3+H2O2 process the extent of reduction were 100%, 95.6% and 80.9% in the same order. The combined treatment approach as HC+O3+H2O2 was established as the most efficient approach for complete removal of 2,4,6-TCP with near complete TOC removal.

Degradation of mixture of three pharmaceuticals by photocatalytic ozonation in the presence of TiO2/montmorillonite nanocomposite: Simultaneous determination and intermediates identification

This study addressed the simultaneous degradation of mixture of three pharmaceuticals including metronidazole (MET), ciprofloxacin (CIP) and acetaminophen (APAP) through the photocatalytic ozonation system. TiO2 nanoparticles were immobilized onto montmorillonite (MMT) support irradiated by UVA light in the presence of ozone. The samples were characterized by XRF, SEM, TEM, PL and N2 adsorption–desorption analysis. A rapid and sensitive chemometrics technique was then developed for the simultaneous determination of the three pharmaceuticals in their mixtures during the photocatalytic ozonation process. A UV–vis spectrophotometer was used for recording the absorption of the pharmaceuticals. The concentration of these pharmaceuticals was successfully determined using a PLS method, despite the severe overlap of their spectra. A central composite design (CCD) was utilized to analyze, model and optimize the effect of each operational parameter on multiple responses including MET degradation (Y1), CIP degradation (Y2) and APAP degradation (Y3). A multi response optimization approach based on a global desirability function (DF) of the factors was employed to simultaneously maximize the response factors. 25mgL−1 MET, 5mgL−1 CIP, 5mgL−1 APAP, 10Lh−1 ozone flow rate and a 15min of reaction time were found to be the ideal conditions at which the degradation of these pharmaceuticals could be simultaneously maximized (Y1=64.60%, Y2=80.58% and Y3=50.12%). Finally, the intermediate by–products of the drugs formed in the degradation process were identified using the GC–MS technique.

Photocatalytic ozonation of metronidazole by synthesized zinc oxide nanoparticles immobilized on montmorillonite

Abstract Released antibiotics in the aquatic environment have undesirable biological and ecotoxicological effects. In this work, photocatalytic ozonation process was used for removal of metronidazole (MET) as commonly used antibiotic from aqueous media. ZnO nanoparticles as an effective photocatalyst were immobilized on the surface of montmorillonite (MMT). The ZnO/MMT catalyst was characterized by X-ray diffraction (XRD), N2 adsorption/desorption, Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and high resolution transmission electron microscope (HR-TEM). The ZnO/MMT activity was examined in the degradation of metronidazole under ozone bubbling and UV-A irradiation through photocatalytic ozonation process. The main influence factors on the photocatalytic ozonation activity such as ZnO/MMT dosage, pH, metronidazole initial concentration and ozone flow rate were studied. The results indicated that the MET removal efficiency was increased with increasing all the investigated factors except initial MMT concentration. The effect of organic and inorganic radical scavengers on the photocatalytic ozonation of MET was studied. Finally, several by products were identified by GC–MS analysis, which allowed to depict a possible mechanism for the MET degradation.

Mineralization and biodegradability enhancement of Methyl Orange dye by an effective advanced oxidation process

An effective process for the oxidation of Methyl Orange dye (MO) was determined by comparing the mineralization efficiency between two advanced oxidation processes (AOPs) viz., ozonolysis and gamma radiolysis in presence and absence of an added inorganic salt potassium persulfate (K2S2O8). The effects of various operating parameters such as ozone flow rate and reaction temperature were optimized to achieve the best possible mineralization extent of MO by ozonolysis. The mineralization efficiency of MO was significantly enhanced during gamma radiolysis in presence of K2S2O8 (γ+K2S2O8) compared to in absence of K2S2O8. The presence of methyl group at the amine of phenyl ring assisted the mineralization of dye during γ+K2S2O8. The oxygen-equivalent chemical-oxidation capacities (OCC) of ozonolysis and γ+K2S2O8 for 75% mineralization of the dye solution were calculated as 7.008 and 0.0336kg equiv. O2 m−3, respectively which signifies that γ+K2S2O8 can be explored as an effective AOP. The non-biodegradable MO dye solution became biodegradable even after the dose of 0.5 kGy during γ+K2S2O8 compared to 1 kGy in absence of K2S2O8. The study concludes that a lower dose γ+K2S2O8 could be one of the efficient pretreatment steps before undergoing biological degradation of dye solution.

A review and investigation of the effect of nanophotocatalytic ozonation process for phenolic compound removal from real effluent of pulp and paper industry.

Phenol and its derivatives are the major environmental pollutants discharged from paper and pulp industries into water bodies. All these compounds and chlorinated phenolic compounds in particular are very toxic to fauna and flora, even at relatively low concentration. This study aimed to investigate the removal rate of phenolic compounds from the effluent of pulp and paper industries using a combination of ozonation and photocatalytic processes. Firstly, a certain volume from the effluent of paper and pulp industries containing certain phenol concentrations was obtained and fed into a prefabricated reactor at laboratory scale. Then, the combined and separate effects of zinc oxide dosage (ZnO), ozone flow rate (O3), and pH under ultra violet radiation for 30min were evaluated. The concentration of phenolic compounds and the produced ozone gas flow rate were measured by a spectrophotometry and iodometric method, respectively. The results showed that the phenolic removal rate increased at acidic PHs compared with alkaline PHs; it was also decreased with the increase in ZnO dosages. Furthermore, the highest phenolic compound's removal rate was 99% at the optimal condition (pH5, ZnO dosage of 0.1gL-1 at the 30min with UV-C illumination of 125W). Finally, Daphnia toxicity test showed that treated effluent was safe and met the standards to the extent that it can be discharged into the receiving waters. Graphical abstract ᅟ.

Copper recovery from reverberatory furnace flue dust

In this study, leaching of reverberatory furnace dust at Sarcheshmeh was investigated in H2SO4-O3 medium. Response surface methodology based on central composite face-centered design (RSM-CCF) was applied to optimize the operating parameters. The optimal conditions to achieve the principle objectives of maximizing copper dissolution and minimizing iron dissolution from dust were identified to be a temperature of 30°C, a leaching time of 3h, an initial pH of 0.5, a pulp density of 20%, and an ozone flow rate of 1g/h. Under the optimum conditions, the copper and iron concentrations in the leaching solution were found to be 27.11 and 0.90g/L, respectively. The results showed that selective copper extraction from the dust could be achieved using sulfuric acid and ozone.

Enhanced Removal of COD and Color in Paper-making Wastewater by Ozonation Catalyzed by Fe Supported on Activated Carbon

After biological treatment, pulp and paper mill effluent still may contain large amounts of recalcitrant organic pollutants that need to be further treated. In this study, Fe supported on activated carbon (Fe@AC) was prepared and used as a catalyst in the catalytic ozonation of pulp and paper mill effluent. The activity of this catalyst was studied in terms of color and chemical oxygen demand (COD) removal efficiencies. Results showed that the COD removal rate was increased by 21% in the presence of the Fe@AC catalyst. After 60 min of ozonation (3g/h ozone flow rate) of the pulp and paper mill effluent (initial COD 360 mg/L), COD removal rates reached 56% in the presence of Fe@AC, 43% using AC as catalyst, and only 35% with ozonation alone. Ozone alone can achieve satisfactory color removal results. Owing to the scavenging effect of carbonate and bicarbonate ions towards hydroxyl radicals, the COD removal rate in Fe/AC catalytic ozonation of the effluent was strongly inhibited in the presence of these two ions. The COD removal rate followed the pseudo-second-order kinetics model well. The COD removal rate constant in the Fe@AC/O3 process was about 1.6 times higher than that of the AC/O3 process, and approximately 2.1 times higher than that of ozone alone.

Degradation of 2,4-dichlorophenol using combined approach based on ultrasound, ozone and catalyst

The present work investigates the application of ultrasound and ozone operated individually and in combination with catalyst (ZnO and CuO) for establishing the possible synergistic effects for the degradation of 2,4-dichlorophenol. The dependency of extent of degradation on the operating parameters like temperature (over the range of 30–36°C), initial pH (3–9), catalyst as ZnO (loading of 0.025–0.15g/L) and CuO (loading of 0.02–0.1g/L) and initial concentration of 2,4-DCP (20–50ppm) has been established to maximize the efficacy of ultrasound (US) induced degradation. Using only US, the maximum degradation of 2,4-DCP obtained was 28.85% under optimized conditions of initial concentration as 20ppm, pH of 5 and temperature of 34°C. Study of effect of ozone flow rate for approach of only ozone revealed that maximum degradation was obtained at 400mg/h ozone flow rate. The combined approaches such as US+O3, US+ZnO, US+CuO, O3+ZnO, O3+CuO, US+O3+ZnO and US+O3+CuO have been subsequently investigated under optimized conditions and observed to be more efficient as compared to individual approaches. The maximum extent of degradation for the combined operation of US+O3 (400mg/h)+ZnO (0.1g/L) and US+O3 (400mg/h)+CuO (0.08g/L) has been obtained as 95.66% and 97.03% respectively. The degradation products of 2,4-DCP have been identified using GC–MS analysis and the toxicity analysis has also been performed based on the anti-microbial activity test (agar-well diffusion method) for the different treatment strategies. The present work has conclusively established that the combined approach of US+O3+CuO was the most efficient treatment scheme resulting in near complete degradation of 2,4-DCP with production of less toxic intermediates.

Fe-Mn bi-metallic oxides loaded on granular activated carbon to enhance dye removal by catalytic ozonation.

A Fe-Mn bi-metallic oxide supported on granular activated carbon (Fe-Mn GAC) has been fabricated by an impregnation-desiccation method and tested in the catalytic ozonation of methyl orange (MO) degradation and mineralization. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations revealed that Fe-Mn oxides were successfully loaded and uniformly distributed on the GAC, and nitrogen adsorption isotherms showed that the supported GAC retained a large surface area and a high pore volume compared with the pristine GAC. The catalytic activity was systematically assessed by monitoring the MO removal efficiencies at different operational parameters, such as catalyst dosage, initial solution pH, and ozone flow rate. The Fe-Mn GAC exhibited better catalytic activity relative to ozone alone and GAC alone, improving the TOC removal by 24.5 and 11.5% and COD removal by 13.6 and 7.3%, respectively. The reusability of the hybrid was examined over five consecutive cyclic treatments. The Fe-Mn GAC catalytic activity was only a slight loss in the cycles, showing good stability. The addition of Na2CO3 as hydroxyl radicals (•OH) scavengers proved that the catalytic ozonation mechanism was the enhanced generation of •OH by the Fe-Mn GAC. The above results render the Fe-Mn GAC an industrially promising candidate for catalytic ozonation of dye contaminant removal.

Degradation of p-nitrophenol (PNP) in aqueous solution by a micro-size Fe0/O3 process (mFe0/O3): Optimization, kinetic, performance and mechanism

A micro-size Fe0/O3 process (mFe0/O3) was setup to degrade p-nitrophenol (PNP) in aqueous solution, and its key operational parameters (i.e., initial pH, ozone flow rate, and Fe0 dosage) were optimized by the semibatch experiments, respectively. Under the optimal conditions, COD removal efficiency (89.5%) obtained by the mFe0/O3 process was about two times of the sum (44.8%) of COD removal obtained by Fe0 alone and O3 alone. The results suggest that the synergetic effect between O3 and Fe0 in the mFe0/O3 process played a vital role in the degradation of PNP. In addition, treatment efficiency of the mFe0/O3 process also was much higher than some of the present technologies (e.g., Fe0/air process, MnO2/O3 and Al2O3/O3), which confirm the superiority of the mFe0/O3 process. Furthermore, the degradation mechanism and pathway of PNP was proposed according to the analysis results of UV–vis, FTIR, IC and GC–MS. According to the present literature and analysis data of SEM, EDS and XRD analysis, it can be concluded that the high-efficient mFe0/O3 process was mainly resulted from the combination of homogeneous or heterogeneous catalytic ozonation, Fenton-like reaction, adsorption and precipitate. Therefore, the mFe0/O3 process was a promising technology for the refractory industrial wastewater.

COD and Color Removal from Real Dyeing Wastewater by Ozonation

ABSTRACT: Ozonation of real dye wastewater for removal of color and COD reduction covering a wide range in operating parameters forms the scope of the present work. The influence of parameters such as influent pH, ozone flow rate and initial effluent concentration on ozonation efficiency has been critically examined. It has been observed from the present investigation that a maximum of COD removal efficiency of 92.5% has been achieved under optimum operating conditions (pH=11; ozone flow rate: 6×10−3 m3/minute). Further the biodegradability index of the dye effluent has increased from an initial value of 0.18 to 0.49 during ozonation indicating favorable adaptation of ozonation as a primer to the biochemical technique to enhance the efficiency of biochemical treatment.

Ozonation of Reactive Orange 122 Using La3+-Doped WO3/TiO2/Sep Photocatalyst

ABSTRACTLa3+/WO3/TiO2/sep composites have been prepared by the sol–gel method. The degradation of dye was studied under the influence of various operational parameters such as initial pH, amounts of catalyst, concentrations of the dye, and ozone flow rate. The mineralization of Reactive Orange 122 has been confirmed by chemical oxygen demand measurements. The color removal of dye was found to follow a pseudo–first-order kinetics. Maximum color and chemical oxygen demand removal were 99.9% and 90% respectively, at a dye concentration of 200 mg/L, ozone flow rate of 2.0 L/min., 0.05 g/L weight of catalyst, and pH of 6.9 in 4 h. In addition, the catalyst was characterized by X-ray diffraction spectra, Fourier-Transform Infrared Spectroscopy, scanning electron microscopy, and a transmission electron microscope. This work could be a good candidate as a practical application for photocatalytic dye degradation.

Multi response optimization of oil palm frond pretreatment by ozonolysis

Oil palm frond (OPF) is a promising feedstock for the second-generation biofuel. However, the recalcitrant lignin layer conceals the cellulose component in the OPF and thus, curtails the conversion of cellulose to the value-added chemicals. The ozonolysis pretreatment is envisaged as an effective method for lignin degradation. This study investigated the influence of OPF particle size, moisture content, reaction time, ozone flowrate as well as their interaction, on lignin degradation and total reducing sugar (TRS) recovery by response surface methodology (RSM). The experiments conducted were based on Box-Behnken design (BBD). The process condition for the optimum lignin degradation and TRS recovery was determined by desirability function. The RSM analysis revealed that the interaction of particle size–moisture content was important for the lignin degradation while the interaction of moisture content–reaction time during ozonolysis was crucial for TRS recovery. Both the lignin degradation and TRS recovery at 84.7wt.% and 99.9%, respectively were optimized simultaneously under the recommended optimum conditions. The pre-treated OPF under the optimum conditions yield the levulinic acid equivalent to the commercial cellulose.

Ozonation optimization and modeling for treating diesel-contaminated water

The effect of ozonation on treatment of diesel-contaminated water was investigated on a laboratory scale. Factorial design and response surface methodology (RSM) were used to evaluate and optimize the effects of pH, ozone flow rate, and contact time on the treatment process. A Box–Behnken design was successfully applied for modeling and optimizing the removal of total petroleum hydrocarbons (TPHs). The results showed that ozonation is an efficient technique for removing diesel from aqueous solution. The determination coefficient (R2) was found to be 0.9437, indicating that the proposed model was capable of predicting the removal of TPHs by ozonation. The optimum values of experimental initial pH, degree of O3, and reaction time were 7.0, 1.5, and 35min, respectively, which could contribute to approximately 60% of TPH removal. This result is in good agreement with the predicted value of 57.28%.

피루브산의 오존산화반응에 미치는 TiO2첨가 및 UV 조사의 영향

Ozonation was investigated for its ability to remove pyruvic acid in a laboratory-scale batch reactor under various experimental conditions, including UV irradiation, TiO₂ addition, and variations in temperature. An ozone flow rate of 1.0 L min^-1 and a concentration of 75±5 mg L^-1 were maintained throughout the experiment, and pH, COD, and TOC were measured at 10 min intervals during a 60 min reaction. Our results confirmed that the combination of UV irradiation and photocatalytic TiO₂ in the ozonation reaction improved the removal efficiency of both COD and TOC in aqueous solution at 20℃. Pseudo first-order rate constants and activation energies were quantified based on the COD and TOC measurements. We observed that the O₃/UV, O₃/UV/TiO₂ system increased mineralization and reduced the activation energy (E_a) necessary for pyruvic acid decomposition.

Mineralization of ammunition wastewater by a micron-size Fe0/O3 process (mFe0/O3)

A micron-size Fe0/O3 process (mFe0/O3) was set up to mineralize the pollutants in ammunition wastewater, and its key operational parameters (e.g., initial pH, ozone flow rate, and mFe0 dosage) were optimized by the batch experiments, respectively.