Ozone In Liquid Phase Research Articles

Development of advanced hybrid mechanistic-artificial intelligence computational model for learning of numerical data of flow in porous membranes

Numerical analysis and machine learning regression were carried out for understanding and description of ozonation process combined with membrane separation. The main focus was on mass transfer modeling to simulate concentration distribution of ozone in liquid phase. Machine learning regression models were utilized to decrease the computational expenses of CFD (Computational Fluid Dynamics) simulations. For machine learning models, we compared the performance of three regression models, namely Gaussian Process Regression (GPR), Deep Neural Network (DNN), and Extreme Gradient Boosting (XGB or XGboost) for predicting the obtained output of CFD simulations which was ozone concentration in the feed, i.e., C (mol/m3) as function of radial and axial coordinates. Hyper-parameter tuning for these models was performed using the Tabu Search algorithm. The results indicate that both GPR and DNN models achieved excellent prediction accuracy, with R-squared values of 0.99999 and 0.99998, respectively. Also, the RMSE for GPR and DNN were 3.8481E-03 and 4.9835E-03, respectively, while their maximum errors were 6.08501E-02 and 4.47909E-02, respectively. On the other hand, the XGB model showed a lower performance, with an R-squared value of 0.99402, an RMSE of 8.9484E-02, and a maximum error of 4.51381E-01

Propuesta de ruta de degradación del BPA durante la reacción del ozono

Endocrine-disrupting compounds (EDC) are present in surface water bodies that supply water to the population. One of them is bisphenol A (BPA), which is listed as a carcinogen. This research addresses its degradation through the ozone reaction and presents a likely pathway established by analyzing products and degradation products using gas chromatography-mass spectrometry (GC-MS). BPA degradation was carried out under pseudo-first-order conditions, where liquid phase ozone was the limiting reactive, in doses of ≈2.29 × 10-4 M and BPA doses of 1.25 × 10-4, 17.5 × 10-4, and 35.0 × 10-4 M, looking to have molar ratios [BPA]> [O3]; the oxidation reaction was carried out in a stopped-flow system that allows obtaining results in the order of seconds. The degradation pathway obtained shows the rupture of one of the benzene rings, decreasing the phenolic toxicity of the BPA compound. The proposed pathway can contribute to the understanding of the degradation of BPA in the environment and tertiary treatment processes with the use of ozone. Likewise, it is intended to contribute with new data to the issues of drinking water treatment to offer safe water to the population.

ELECTROCHEMICAL OZONE GENERATION FOR PALM OIL MILL WASTEWATER TREATMENT USING NICKEL/ANTIMONY DOPED TIN OXIDE ANODES

Ozonation have been employed in organic matter degradation and discoloration process of wastewater. In this study, nickel-antimony doped tin oxide (NATO) anode was employed to generate ozone for palm oil mill effluent (POME) wastewater treatment. NATO was synthesized varying Ni concentrations and calcination temperatures. The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. All materials showed rutile structure. The electrode displayed a smooth cracked mud surface morphology. Regarding the oxidation state, the binding energies of the Sb 3d3/2 peak were observed at 540.62 eV and 541.51 eV corresponding to Sb3+ and Sb5+, respectively. The key findings show that increasing calcination temperature increases ozone current efficiency obtained from the absorbances of dissolved ozone in liquid phase and current density, which decreases with increasing Ni content. The highest current efficiency and current density (i.e. ca. 30% and 0.18 Acm-2 in 1 M H2SO4 at 2.7V) was achieved at 2%mole ratio Ni content calcined at 650°C. Regarding POME treatment, discoloration and degradation efficiency increased with electrolysis time from the initial chemical oxygen demand (COD) and total organic carbon (TOC) of 1,780 and 96 mgL-1, respectively under the aforementioned conditions. The highest removal efficiency of 80% was achieved within 10 min discoloration and 15 min for TOC and COD. The electrochemical ozone generation using NATO anode have shown high efficiency in the POME treatment due to •OH radicals and O3. NATO is a promising electrocatalyst candidate for wastewater treatment.

An insightful analysis of dimethyl phthalate degradation by the collaborative process of DBD plasma and Graphene-WO3 nanocomposites

In this paper, the prepared graphene-WO3 nanocomposites (rGO-WO3) were added into a dielectric barrier discharge (DBD) plasma system with spiral discharge electrode to set up a collaborative process to treat the dimethyl phthalate (DMP) in water. Degradation of the DMP under different experimental conditions were studied to illustrate the catalysis of the rGO-WO3 in the DBD plasma system. The obtained results proved that there was the catalysis of the rGO-WO3 for the DMP degradation within the studied DMP concentration, solution initial pH values and conductivities. From the results of the energy utilization efficiency (G50) analysis, the catalysis was more apparent in the case of the oxygen bubbling system than that in the nitrogen or the air bubbling system, which was due to the higher oxygen constitution in the oxygen bubbling system. The reduction of the measured liquid phase ozone concentrations in the DBD/rGO-WO3 system bubbled with air as well as oxygen than those measured in the sole DBD system, which verified the consumption of the ozone by the catalysis of the rGO-WO3. Furthermore, the UV–Vis and the three-dimensional fluorescence spectra analysis were also carried out to state the catalytic effect of the rGO-WO3 for the DMP degradation. Toxicity analysis for the degradation byproducts confirmed the collaborative process could reduce the negative effect of the original DMP on the environment.

Liquid spray transport of air–plasma-generated reactive species toward plant disease management

Liquid–phase transport of plasma-generated reactive species toward large-scale plasma treatment for agricultural applications is experimentally studied. The liquid-phase reactive species in this study are generated by the contact of water solution with air–plasma effluent gas containing mainly low-solubility reactive species under elevated pressure, followed by spraying the plasma effluent gas dissolved solution into a target pathogenic conidium suspension. Low-solubility ozone in the liquid phase at the target is found to dominate the observed germination suppression effect, which also correlates with the gas-phase ozone density. The measured ozone concentration at the target is found to be ten times lower than the ozone concentration at saturation, estimated from Henry’s law with the measured gas-phase ozone density. The liquid-phase ozone loss mechanism during the transport of the sprayed liquid is interpreted as volatilization and reactions with co-dissolved species. The deduced control parameters for precise ozone transport are the droplet diameter of the sprayed solution, sprayed jet flow, and co-dissolved reactant with the liquid-phase ozone such as nitrite.

Mineralization of petrochemical wastewater after biological treatment by ozonation catalyzed with divalent iron tartaric acid chelate.

The petrochemical wastewater includes many toxic organic compounds, which are refractory substances. It is difficult for the wastewater to meet discharge standards after biological treatment, therefore, the further effective treatment of post-biochemical petrochemical wastewater has become an urgent problem to be solved. This study used iron tartaric acid chelate (ITC) catalytic ozonation to treat the petrochemical wastewater. Various key factors were investigated, such as hydraulic retention time (HRT), catalyst dosage, ozone concentration, initial pH values and oxidation efficiency. The kinetics of catalytic ozonation were established. The results indicate that the chemical oxygen demand (COD) removal rate reached a maximum of 58.5%, when the Fe2+ dosage is 0.25 mmol L-1, the initial pH value is neutral, the liquid phase ozone concentration is about 1.95 mg L-1, and HRT is equal to 180 min. In addition, when HRT is equal to 90 min, the B/C ratio of wastewater increases to 0.31, the catalytic ozone reaches maximum oxidation efficiency, and the most economical HRT was 90 min. Finally, the kinetics of ITC catalytic ozonation catalyzed with ITC is consistent with the pseudo-first-order kinetic reaction, and its rate constant is 0.00484 min-1.

Modeling of Ozonation of Reactive Black 5 Through a Kinetic Approach

C.I. Reactive Black 5 (RB5) is the most commonly used dye in the textile industry. Ozone is a strong oxidan that can decompose many barely degradable pollutants, including dyes. Although there are many literature reports devoted to the treatment of textile wastewater and dye solutions by ozone, the ozonation mechanism and modeling of the kinetics is still not well covered. In this work a kinetic model of the process of RB5 decolourisation by ozone has been proposed and validated on the basis of experimental data. The experiments were carried out in a liquid-liquid system to avoid mass transfer limitation. A model was established for acid reaction medium. The main RB5 reaction was direct oxidation of the dye with molecular ozone. The self-decomposition of ozone in liquid phase was taken into account and described by an empirical equation. The reaction rate constants of RB5 with ozone were estimated from the experimental data in the range of (1.88 ± 0.08) × 104 – (2.53 ± 0.10) × 105 M-1s-1 (invariant with initial dye concentration). An empirical equation k2′ = 1.06 × 108(COH−)0.31 was built for the constant to make it dependent on the pH value. A solution of the non-linear inverse problem allowed for identification of the kinetic constants on the basis of the experimental data obtained. The model gave a good match between the prediction and experimental data for pH between 1.88 and 4.0.

Immunization Effect of Sodium Aluminate on Wool

C.I. Reactive Black 5 (RB5) is the most commonly used dye in the textile industry. Ozone is a strong oxidan that can decompose many barely degradable pollutants, including dyes. Although there are many literature reports devoted to the treatment of textile wastewater and dye solutions by ozone, the ozonation mechanism and modeling of the kinetics is still not well covered. In this work a kinetic model of the process of RB5 decolourisation by ozone has been proposed and validated on the basis of experimental data. The experiments were carried out in a liquid-liquid system to avoid mass transfer limitation. A model was established for acid reaction medium. The main RB5 reaction was direct oxidation of the dye with molecular ozone. The self-decomposition of ozone in liquid phase was taken into account and described by an empirical equation. The reaction rate constants of RB5 with ozone were estimated from the experimental data in the range of (1.88 ± 0.08) × 104 – (2.53 ± 0.10) × 105 M-1s-1 (invariant with initial dye concentration). An empirical equation k2′ = 1.06 × 108(COH−)0.31 was built for the constant to make it dependent on the pH value. A solution of the non-linear inverse problem allowed for identification of the kinetic constants on the basis of the experimental data obtained. The model gave a good match between the prediction and experimental data for pH between 1.88 and 4.0.

Degradation of Acid Orange 7 Dye in Two Hybrid Plasma Discharge Reactors

To get an optimized pulsed electrical plasma discharge reactor and to increase the energy utilization efficiency in the removal of pollutants, two hybrid plasma discharge reactors were designed and optimized. The reactors were compared via the discharge characteristics, energy transfer efficiency, the yields of the active species and the energy utilization in dye wastewater degradation. The results showed that under the same AC input power, the characteristics of the discharge waveform of the point-to-plate reactor were better. Under the same AC input power, the two reactors both had almost the same peak voltage of 22 kV. The peak current of the point-to-plate reactor was 146 A, while that of the wire-to-cylinder reactor was only 48.8 A. The peak powers of the point-to-plate reactor and the wire-to-cylinder reactor were 1.38 MW and 1.01 MW, respectively. The energy per pulse of the point-to-plate reactor was 0.2221 J, which was about 29.4% higher than that of the wire-to-cylinder reactor (0.1716 J). To remove 50% Acid Orange 7 (AO7), the energy utilizations of the point-to-plate reactor and the wire-to-cylinder reactor were 1.02 × 10−9 mol/L and 0.61 × 10−9 mol/L, respectively. In the point-to-plate reactor, the concentration of hydrogen peroxide in pure water was 3.6 mmol/L after 40 min of discharge, which was higher than that of the wire-to-cylinder reactor (2.5 mmol/L). The concentration of liquid phase ozone in the point-to-plate reactor (5.7 × 10−2 mmol/L) was about 26.7% higher than that in the wire-to-cylinder reactor (4.5 × 10−2 mmol/L). The analysis results of the variance showed that the type of reactor and reaction time had significant impacts on the yields of the hydrogen peroxide and ozone. The main degradation intermediates of AO7 identified by gas chromatography and mass spectrometry (GCMS) were acetic acid, maleic anhydride, p-benzoquinone, phenol, benzoic acid, phthalic anhydride, coumarin and 2-naphthol. Proposed degradation pathways were elucidated in light of the analyzed degradation products.

Effect of liquid-phase O3 oxidation of activated carbon on the adsorption of thiophene

In this work, a combined experimental and computational study is carried out to investigate the effect of O3 oxidation of activated carbon (AC) in various types of aqueous media (alkaline, acidic and neutral aqueous solutions) on the adsorption of thiophene. A high surface area AC (BET surface area of 2880m2/g) is modified by ozone-oxidation in different aqueous media under ambient conditions. Experimental results show liquid phase ozone oxidation of AC introduces oxygen functional groups to the AC surface, resulting in enhanced adsorption capacity of thiophene. The impact of oxidation media on the adsorption capacity follows the order of NaOH>H2SO4>H2O, consistent with the order of the concentrations of oxygen functionalities introduced on the carbon surface. Computational results suggest that phenol and carboxyl groups on the surface lead to stronger thiophene adsorption than the bare (unfunctionalized) graphite surface, corroborating our experimental results. Additionally, the presence of bridging-oxygen functionalities on the carbon surface leads to extremely exothermic adsorption energies of thiophene, which can be attributed to sulfoxide formation and H-bonding interactions. DFT calculations suggest the adsorption strength of thiophene follows the order of bridging-O-functionalized (Ads E=−1.51eV)≫OH-functionalized (Ads E=−0.36eV)>COOH-functionalized (Ads E=−0.27eV)>bare graphite (Ads E=−0.26eV). The combined experimental and computational study provides direction for carbon surface functionalization for adsorptive desulfurization.

P28: Mechanisms underlying nitrite reduction in hypertension: Role for erythrocytic xanthine oxidoreductase

Within the human circulation physiological levels of nitrite can act as a source of NO and as such exert important vasodilator effects (Cosby et al., Nat. Med. 9 (2003) 1498–1505). It is now accepted that the red blood cell (RBC) is an important site for nitrite reduction and it has been proposed that deoxyhaemoglobin is the primary nitrite reductase within this cell type under physiological conditions. In addition, our previous studies have shown that purified RBCs collected from healthy volunteers facilitate nitrite reduction that is dependent upon activity of endothelial nitric oxide synthase (eNOS) at pH 7.4, and xanthine oxidoreductase (XOR) at more acidic pH (6.8) (Webb et al., Circ Res 103 (2008) 957–964). Whether such a profile might also be evident in hypertension is unknown. We investigated RBC nitrite reductase activity in the spontaneously hypertensive rat (SHR) and Wistar Kyoto (WKY) strain controls and in patients with hypertension. Male SHR (SBP 153.4 ± 3.9, DBP 101.1 ± 2.7 mm Hg) and WKY (SBP 119.3 ± 2.6, DBP 74.4 ± 3.8 mm Hg) (14–16 weeks of age, Charles River, UK) were anaesthetized for blood collection. Hypertensive patients (SBP 151.5 ± 1.8, DBP 89.7 ± 2.2 mm Hg) were recruited and blood samples collected. Plasma and erythrocyte nitrite and nitrate concentration were measured by liquid phase ozone chemiluminescence. The nitrite reductase activity of blood vessel homogenates or purified RBCs was determined using gas phase ozone chemiluminescence. To ascertain the role of XOR in any activity seen samples were incubated with the XOR inhibitor allopurinol (100 μmol/L) for 30 min. XOR protein expression was quantified using Western blotting. There were no differences in nitrite and nitrate concentrations in the plasma (n = 18) and aortic homogenates (n = 12–15) between SHRs and WKY controls. Levels of RBC nitrite (WKY 53.4 ± 10.0 nmol/g; SHR 7.8 ± 1.3 nmol/g, p < 0.001) and nitrate (WKY 706.0 ± 187.2 nmol/g; SHR 268.4 ± 45.1 nmol/g, p < 0.05) were significantly lower in SHR (n = 8) compared to WKY (n = 4), respectively. Nitrite-derived (300 μmol/L) NO formation was similar in blood vessel homogenates of SHR (n = 5) and WKY (n = 5) at pH 7.4 and 6.8, however erythrocytic nitrite reductase activity of SHRs (n = 8) was substantially enhanced compared to WKY (9i = 4) at pH 7.4 (p < 0.05). Furthermore, allopurinol (100 μmol/L) virtually abolished this activity in SHRs at pH 7.4 (n = 8, p < 0.001) and pH 6.8 (n = 8, p < 0.001). In contrast, no effect of allopurinol was evident in erythrocytic nitrite reductase activity of WKY (n = 4). Western blotting for erthrocytic XOR demonstrated a doubling of expression in SHRs. Erythrocytes isolated from the blood of grade 1 hypertensives (n = 11) caused concentration-dependent NO generation that was attenuated by allopurinol at pH 7.4 (p < 0.001) and pH 6.8 (p < 0.001). This enhanced activity in hypertensive volunteers was associated with an approximate doubling of erythrocytic XOR expression. Our findings suggest that in hypertension the RBC is an important site for nitrite reduction within the circulation and that XOR acts as a major nitrite reductase. SMG is funded by an MRC MRes Ph.D. and this work was supported by the BHF. MRC MRes PhD students hiPBHF support.

Formal Bimolecular Kinetic Model for the Ozonation of Ciprofloxacin in the Liquid Phase

AbstractA bimolecular kinetic model is proposed for the liquid phase ozonation of organic components, incorporating direct and indirect ozonation by means of bimolecular reaction steps. One of the advantages of this model is that all radicals, present in the liquid phase, are lumped into one concentration, reducing the number of kinetic parameters. The main objective of this paper is to determine the degradation kinetics of ciprofloxacin (CIP), as model component for the class of fluoroquinolones, in order to validate the proposed kinetic model on available experimental data, obtained in a lab scale bubble column reactor. Additionally, different reactor models such as a continuous stirred tank reactor (CSTR) and a plug flow reactor (PFR) are compared in the description of the experimental data. A realistic mass transfer coefficient for ozone from the gas to the liquid phase of 1.65 10

Study of reaction of isomeric acetoxytoluenes with ozone in liquid phase in the presence of manganese bromide catalyst

The kinetics of the ozone reaction with isomeric acetoxytoluenes in acetic anhydride in the presence of sulfuric acid and mixed manganese bromide catalyst was studied. Under these conditions it is possible to stop the oxidation process at the stage of formation of hydroxybenzaldehydes in the form of the respective acetoxybenzylidendiacetates (63–70%). The reaction products contain also acetoxybenzyl acetate (16–18%) and a small amount of acetoxybenzyl bromide (2%). The mechanism of oxidation-reduction catalysis with manganese bromide complex explaining the experimental data was considered.

Preparation of oxygen-containing organic products from bed-oxidized brown coal by ozonation

The possibility of modifying the functional composition of humic acids by gas-phase ozonation of bed-oxidized brown coal was examined. About 90% of the organic matter of brown coal was converted to low-molecular-weight soluble oxygen-containing products by stepwise liquid-phase ozonation (in chloroform and acetic acid).

Effects of organic compounds and recycling on ozone absorption in a portable water purification unit

The absorption of ozone gas in a portable bubbling unit was investigated. First, six types of bubblers were tested under identical operating conditions with a gas flow rate of 1 L/min and a water volume of 1.5 L. A simple mass transfer model with the liquid phase assumed to be completely mixed and the axial ozone gas concentration gradient neglected was used to obtain the overall mass transfer coefficient, KLa, by fitting experimental data. The effect of organic compounds in the water on ozone absorption and liquid ozone concentration buildup was investigated experimentally using phenol as a model compound. It was found that the existence of phenol significantly reduced the liquid ozone concentration because absorbed ozone is consumed for the destruction of phenol, leading to the delay in liquid phase ozone concentration buildup. The implication is that the disinfection time was prolonged when water of high organic compounds concentration is to be purified. Using the completely stirred tank reactor model, the gas recycling is simulated and demonstrated to be effective for enhancing ozone utilization efficiency in the small portable water purification unit.

Liquid-phase ozonation of fusainized components of SS coal

Stepwise ozonation of leaning fusainized components of fossil coal of SS grade in acetic acid was studied. The dynamics of accumulation of oxygen-containing groups in the course of ozonation was examined, and the main pathways of the reaction of ozone with structural fragments of the coal substance were revealed.

Liquid-phase ozonation of vitrinites of coals of various metamorphic stages: Product composition

The fractionated products of ozonation of vitrinites of Kuznetsk coals of different metamorphic stages in chloroform have been characterized by IR spectroscopy, thermogravimetry, and gas chromatography-mass spectrometry. High-molecular-mass compounds insoluble in water prevail in the products. Water-soluble products are ketones, oxyalkanols, lower aliphatic acids, and hydroxy-and dicarboxylic aromatic acids.

Iodine oxide in the Dead Sea Valley: Evidence for inorganic sources of boundary layer IO

The importance of iodine oxide (IO) in tropospheric boundary layer chemistry has been well established in the last decade. Iodine‐containing radicals have been detected in regions of high biological productivity. To date, most explanations assume biogenic precursors (e.g., emission of iodocarbons). In a 2 week field campaign at the Dead Sea, Israel, IO was found to exceed the detection limit (0.3–2 parts per trillion (ppt)) almost daily, with peak levels topping 10 ppt. Macro algae are nonexistent because of the water's high salinity. The Dead Sea's microbiology is discussed in detail, and organic sources of iodine oxide are found to be of minor importance. Thus the site can be treated as a unique place for the investigation of inorganic sources of IO. Such processes have recently been included in model studies. Our study focuses on the first direct evidence for inorganic sources of reactive boundary layer iodine. Heterogeneous iodine release induced by photolysis, liquid phase ozone reactions, or catalytic HOX interactions are discussed as well as NOx chemistry.

A refined model for ozone mass transfer in a semibatch stirred vessel

The mathematical model proposed by Anselmi et al. (1984) for a semibatch stirred gas‐liquid contactor is refined to describe the mass transfer of ozone absorption and decomposition in aqueous solution with the decomposition rate expression of general reaction orders (not necessarily integers). Three system equations are employed to describe the ozone concentrations in the bulk liquid (CALb), the hold‐up gas (CAGi), and the outlet gas in the free volume above the liquid surface (CAGe), respectively. The effect of ozone decomposition on the mass transfer, which is reflected by the enhancement factor (Er) defined as the ratio of mass absorbed per unit area in time t with chemical reaction (r) to that without chemical reaction or of the purely physical absorption, is considered in the refined model. Furthermore, the refined model also takes into account the variation of Er with CALb, which changes with time during the course of gas‐liquid contacting. Thus this analysis extends the applicability of the model of Anselmi et al. (1984) and is of special importance for ozone mass transfer in the cases of basic solutions and of low mass transfer coefficients, in which the effect of decomposition on absorption is significant, and in the system with variable liquid phase ozone concentration.

A Preliminary Study of Pulsed Streamer Corona Discharge for the Degradation of Phenol in Aqueous Solutions

Pulsed corona discharges are shown in this investigation to be effective at breaking down phenol in aqueous solutions in an isothermal batch reactor and in a semi-batch reactor with the continuous addition of oxygen. In the experiments where no oxygen was bubbled through the reactor the phenol breakdown was independent of pH, thus indicating significant hydroxyl radical formation directly from the corona discharge. The addition of iron was found to significantly enhance phenol degradation; this may be due to Fenton's reaction arising from hydrogen peroxide formed directly by the corona discharge. In experiments where oxygen was fed to the reactor, it appeared that two simultaneous reaction pathways contributed to phenol degradation. The first pathway consisted of corona-induced aqueous phase reactions. The second pathway arose from ozone production in the gas phase with subsequent mass transfer into the liquid phase followed by liquid phase ozone reactions. The presence of phosphate and borate buffers decreased the rate and magnitude of phenol breakdown at low and high pH, respectively, due to radical quenching.