Occurrence of Aflatoxin M1 in Dairy Products in Southern Italy

A screening survey of the presence of aflatoxin M₁ (AFM₁) was carried out on 265 samples of cheese made from cow, buffalo, goat, sheep, sheep-goat milk collected in the Apulia region (Southern Italy). Selected samples included unripened, medium and long-term ripened cheeses. AFM₁ was found in 16.6% of the analyzed samples. The highest positive incidence was for medium and long-term ripened cheeses, especially those made from sheep-goat milk, while buffalo cheeses tested consistently negative. Our results show that the level of contamination by AFM₁ in dairy products from Apulia Region are lower than in other Italian and European regions. Moreover, it is important to underline that a common European norm concerning the AFM₁ threshold limits for dairy products is still lacking.     

Ozone Processing of Peach Juice: Impact on Physicochemical Parameters,Color, and Viscosity

The impact of gaseous ozone on pH, °Brix, titratable acidity, and optical and rheological properties of fresh squeezed peach juice was investigated. Peach juice was exposed to ozone (0.06–2.48 g. L^?1) in a bubble column at 20 ± 1 °C. Nonsignificant or slight changes in pH, °Brix, and titratable acidity were found during ozonation. Lightness (L*) slightly decreased in the first minute of O₃ exposure and then remained practically constant, while a* parameter slightly increased in all treated samples. L* and a* parameters as well as Browning Index values reflected a slight increase in browning in ozonized juices. All juices, treated and untreated, exhibited non-Newtonian flow characteristics with pseudoplastic behavior. Significant reductions in apparent viscosity and a trend toward Newtonian flow as O₃ treatment time increased were observed for ozonized juices. The Power Law model was suitable to fit rheological data.     

Effects of O3, O3/H2O2 and Coagulation on Natural Organic Matter and Arsenic Removal from Typical Northern Serbia Source Water

The objectives of this study were to investigate the effects of ozone and the O₃/H₂O₂ process on FeCl₃ coagulation efficiency for the removal of the high content of natural organic matter (NOM) and arsenic (As) from groundwater (DOC = 9.27 ± 0.92 mg/L; 51.7 ± 16.4 µg As/L). Arsenic and NOM removal mechanisms during coagulation/flocculation are well investigated. However, data concerning arsenic removal in the presence of NOM, which is the subject of this article, are still insufficient. Laboratory and pilot plant test results have shown that the competition of NOM and As for adsorption sites on the coagulant surface have great influence on coagulation/flocculation efficiency for their removal. With both oxidation pre-treatments, arsenic content after the coagulation process was less than 2.0 µg/L in treated water. Application of ozone has a lower influence on coagulation efficacy in terms of DOC reduction, compared to the O₃/H₂O₂ process with the same ozone dose.     

Ozone Solubility in Aqueous Solutions of NaCl,Na2SO4, and K2SO4: Application of the Weisenberger-Schumpe Model for Description of Regularities and Calculation of the Ozone Molar Absorption Coefficient

The ozone solubility in aqueous solutions of salts, NaCl (up to 5 М) and Na₂SO₄ (up to 2 М) and their mixtures, was studied. The results are adequately described by the semi-empirical model proposed by Weisenberger and Schumpe for calculation of the solubilities of atmospheric gases in concentrated solutions of electrolytes. By comparing the data obtained experimentally and calculated in terms of the Weisenberger and Schumpe model, the ozone molar absorption coefficient was found to be ε = 2860 ± 200 M^?1 cm^?1 at 260 nm.     

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

La³⁺/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.     

Modeling and experimental of mould disinfestation of soybean silos with ozone

ABSTRACT

This study aimed to develop and validate a mathematical model for predicting ozone propagation and distribution in a bench-scale storage silo of soybean and link the model results to its application as an antifungal. The reduction of potentially toxigenic fungi found in soybeans was also evaluated after the ozone treatment. Experimental validation consisted of the ozone application and concentration (ozone) monitoring at the experimental silo outlet. The soybean grains were analyzed prior to and after ozone treatment from different portions of the silo to evaluate the antifungal activity. After 30 minutes of ozone exposure, there was an 88% reduction in the amount of fungi present at the lower section, reaching total elimination with longer exposure times. Fusarium was the main genus found, and it was significantly reduced even with the shortest exposure (30 min). The results of the ozone propagation in soybeans will be useful to better understand its behavior within silos, in order for the elimination of biological contaminations to occur. The model showed ozone spread through the silo, and this treatment showed to be an effective alternative to control against potentially toxigenic fungi found in soybeans.     

Degradation of Carbamazepine by Photo-assisted Ozonation: Influence of Wavelength and Intensity of Radiation

This article presents the results of an investigation into the function of UV in a photo-assisted ozonation process for treatment of carbamazepine (CBZ) in treated domestic wastewaters. Experiments were conducted on synthetic spiked water and secondary treated municipal wastewater. Degradation of CBZ was studied for various combination of O₃ dosage ranging from 4.8 to 14.4 mg/h and UV intensities with varying intensity and wavelength (UVC: λ = 254 nm and UVA: 352 nm). In synthetic spiked water, CBZ was degraded to below detectable limits within 0.5 min for ozone dose of 14.4 mg/h. The rate of degradation of CBZ increased exponentially with increase in ozone dose following a zero-order rate at each dose level. The degradation rate of CBZ in wastewater was slower compared to deionized water (DI) water by 40–75% for various doses of ozone, presumably due to the presence of organic matter remaining in treated wastewater. Optimal UV intensities for UVA and UVC were obtained as 0.62 and 0.82 mW/cm² for all doses of ozone in synthetic spiked water samples and UV intensities beyond this resulted in lower rates of degradation of CBZ. For photo-assisted ozonation with ozone doses of 9.6 and 14.4 mg/L, rate constants were two times higher for UVA irradiations as compared to UVC irradiation. Contrary to observations in DI water, experiments in wastewater showed increase in rate of degradation with higher UV intensities. Overall, photo-assisted ozonation was found to be appropriate for both water and wastewater treatment by exploiting the benefit of direct attack of ozone and of produced ^?OH radicals to yield a greater extent of mineralization of CBZ.     

Synthesis of fine and high purity Cr2AlC powders by novel method

Cr₂AlC powders using Cr/Al/C and Cr/Al/Cr₃C₂ systems as raw materials were successfully synthesised by a microwave hybrid heating method for the first time. The mixtures of Cr, Al and graphite or Cr₃C₂ with different molar ratios were used to investigate the formation of Cr₂AlC phase. For Cr/Al/C with the molar ratios of 2:(1.0–1.2):1 system, Cr₂AlC with a small amount of Cr₇C₃ and Cr₂Al was synthesised at 1000°C for 3 min, and the average particle size was ?1?μm. For Cr/Al/Cr₃C₂ with the molar ratio of 1:2:1 system, high purity Cr₂AlC powders was synthesised at 1000°C for 3 min, and the average particle size was ?1?μm. The synthesis of high purity Cr₂AlC powders for short time was attributed to the combination of the hybrid heating effect and the introduction of Cr₃C₂ as carbon source. Microwave hybrid heating is a promising method for the preparation of various other MAX phases.     

Application of Ozone in Stripping of Cotton Fabric Dyed with Reactive Dyes

ABSTRACT

This paper discusses the color stripping of cotton fabric dyed with four reactive dyes using ozone. An ozone color stripping process has been optimized in terms of pH, ozone dose, treatment time and dye concentration. Color stripping efficiency of the process is evaluated in light of the color properties including Lightness (L*), Lightness Difference (?L*), and Color Difference (?E*) in addition to strength properties, i.e., copper number and degree of polymerization as well as compared with a control method (conventional reductive color stripping method). The results demonstrate maximum color stripping at an ozone dose of 10 g/h, exposure time of 45 min, and pH maintained at 5. The Stripping Efficiency, however, decreases with increasing dye concentration from 0.5% to 4%, which implies that decolorization of dyed fabric with higher initial dye concentration requires higher ozone dose and/or longer exposure time. The strength of the ozone-stripped fabric sample is almost similar to that of control. The chemical oxygen demand of effluent generated by ozone stripping process is 97% lower than the effluent produced by the conventional stripping method. The Ozone Stripping Process hence proves to be environment-friendly as it consumes less water, energy, and chemicals.     

Inactivation of Bacillus cereus and Salmonella enterica serovar typhimurium by Aqueous Ozone: Modeling and UV-Vis Spectroscopic Analysis

Antibacterial efficacy of aqueous ozone (O₃) against B. cereus vegetative cells and S. typhimurium by was studied by using GInaFiT tool and results were validated using UV-Vis spectroscopy. Ozone gas was generated using a domestic ozone generator. Buffer solutions containing known amounts (≈10⁸–10⁹ cfu/mL) of bacterial pathogens were treated with aqueous ozone (200 mg/hr or 0.1 mg/l) for 16 min with sampling at 0-, 0.5-, 1-, 2-, 4-, 8- and 16-min intervals. A reduction of 4.6 log of B. cereus and 7.7 log cycle reduction of S. typhimurium was obtained in 16 min. Biphasic shoulder and double Weibull models were good fit for the experimental inactivation kinetics data. Principal Component Analysis showed discrete grouping based on the time of treatment. The highest correct classification results for SIMCA were achieved for both B. cereus and S. typhimurium after 1 and 8 min of treatment, respectively. In partial least squares regression analysis, maximum R² values for calibration and validation were found to be 0.84, 0.80 for B. cereus and 0.90, 0.89 for S. typhimurium, respectively.     

Inactivation of airborne viruses using vacuum ultraviolet photocatalysis for a flow-through indoor air purifier with short irradiation time

Many ultraviolet (UV)-based disinfection methods have been developed; however, these methods usually use the recirculating mode or need long irradiation periods due to its low photon energy. Vacuum UV (VUV) was recently found to be a promising light source, despite its ozone generation. In this study, we investigated photocatalysis reactions by VUV with short irradiation times (0.004–0.125 s) for simultaneously inactivating airborne MS2 viruses and degrading the generated ozone toward a flow-through air disinfection system with high flow-rates. We developed three effective shapes for the catalyst frame: 2 mm and 5 mm pleated, and spiral-type Pd-TiO₂ catalysts. The 2 mm pleated Pd-TiO₂/VUV photocatalyst exhibited the highest activity for simultaneous MS2 inactivation and ozone degradation, and the catalytic activity was effective regardless of relative humidity. Considering the gas phase and catalyst surface effects, and the natural inactivation of VUV-irradiated but live MS2 viruses, the 2 mm pleated Pd-TiO₂/VUV and succeeding UV photocatalysis showed more than 90% in the overall inactivation efficiency with residual ozone of 35 ppb at an irradiation time of 0.009 s (flow-rate: 33 l/min). In contrast, most UV-based purifiers take longer times for disinfection. This system has the potential for an alternative to conventional UV-based air purifiers.

Copyright © 2018 American Association for Aerosol Research     

The Benefits of Small Quantities of Nitrogen in the Oxygen Feed to Ozone Generators

This paper reports the ozone generation in pulsed multichannel dielectric barrier discharge. The influence of nitrogen addition (0.1%–10%) on ozone concentration and ozone generation efficiency in nitrogen–oxygen gas mixtures is studied. Results show that adding 0.1% N₂ would not seriously increase the ozone production. Meanwhile, 1% N₂ content exhibits the highest ozone production efficiency in low SIE (J/L, defined as the ratio of power to gas flow rate) region (0–200 J/L) while adding 0.3% N₂ would lead to the highest ozone generation efficiency in high SIE region (300–800 J/L). The increase of ozone production induced by N₂ addition is more significant in low SIE region compared with that in high SIE region. At 100 J/L, ozone production efficiency increases 26.9% to 201.6 g/kWh with 1% N₂ addition when compared with that in oxygen. At 18 J/L, the observed maximum ozone generation efficiency reaches 252 g/kWh at 1.3 g/Nm³ with 1% N₂ addition. An increase of ozone production can be obtained with 0.3%–2% N₂ addition in all explored SIE ranges.     

Performance evaluation of ozonation and an ozone/hydrogen peroxide process toward development of a new sewage treatment process—Focusing on organic compounds and emerging contaminants

Performance of ozonation and an ozone/hydrogen peroxide process under a new concept centering on ozonation and/or ozone/hydrogen peroxide processes in sewage treatment processes comprising only physical and chemical processes are discussed, with focus on the removal of matrix organic compounds and emerging contaminants. Matrix organic compounds of filtrated primary sewage effluents were removed to as low as 3.2 mgC/L in the ozone/hydrogen peroxide process at an ozone consumption of around 400 mg/L. Linear relationships between ozone consumption and removal amounts of organic compounds were observed, in which the amounts of ozone required to remove 1 mg of organic carbon were 9.5 and 8.3 mg (2.4 and 2.1 mol-O₃/mol-C) in ozonation and the ozone/hydrogen peroxide process, respectively. Ratios of hydroxyl radical exposure to ozone exposure were in the order of 10^–9 to 10^–8 for ozonation and 10^–7 to 10^–6 for the ozone/hydrogen peroxide process. Experiments and a kinetic evaluation showed that ozonation and/or the ozone/hydrogen peroxide process have high elimination capability for emerging contaminants, even in primary sewage effluent with the thorough removal of matrix organic compounds. Newly found reaction phenomena, the temporal increase and decrease of dissolved ozone and accumulation of hydrogen peroxide in the early stage of oxidation with the continuous feeding of hydrogen peroxide, were presented. Possible reaction mechanisms are also discussed.     

Ozonolysis Post-Treatment of Anaerobically Digested Distillery Wastewater Effluent

ABSTRACT

In this study, the ozonolysis of real anaerobically digested distillery wastewater (DWW) was carried out. The effect of operating parameters, such as pH, initial concentration, and ozone dosage, on the efficiency of ozone utilization, color removal, and sludge solubilization was studied. The highest ozone utilization of 99% was observed at the highest initial concentration (COD of 3000 mg/L) and lowest ozone flowrate (22.5 mg O₃/L/min), but with a very low color reduction of 20%, after 60 minutes of ozonolysis. To achieve a higher color reduction >80% and at ozone utilization >95%, the DWW had to be diluted twice (COD 1500 mg/L), and the flowrate doubled to 45 mg O₃/L/min. The reduction in color signified the oxidation of the color causing biorecalcitrant aromatic melanoidin compounds. This was confirmed by the 47% reduction in ultraviolet absorbance at 254 nm indicating the breakdown of the complex aromatic compounds into low molecular weight organics. Moreover, increases in average oxidation state from ?0.6 to ?0.2 suggested a decline in aromaticity and formation of easily biodegradable aliphatic compounds. The ozonolysis process was found to follow the first-order reaction kinetic model with the highest rate constant of 0.0326 min^?1 obtained. A reduction in suspended COD by 88% indicated solubilization of the sludge contained in the effluent.     

The removal of cephalexin antibiotic in aqueous solutions by ultrasonic waves/hydrogen peroxide/nickel oxide nanoparticles (US/H2O2/NiO) hybrid process

ABSTRACT

Antibiotics are non-biodegradable and can remain for a long time at aquatic environments and they have a big potential bio-accumulation in the environment. The antibiotics are broadly metabolized by humans, animals and plants and they or their metabolites, after metabolization, are entered into the aquatic environment. This study aimed to optimize the operational parameters by Taguchi design and to carry out the kinetic studies for removal of cephalexin antibiotic from aqueous solutions by US/H₂O₂/NiO hybrid process. This experimental study was performed on a laboratory scale in a 500 mL pyrex-made reactor. The main operational parameters to influence the US/H₂O₂/NiO process were identified as the initial concentration of CEX (20–80 mg/L), hydrogen peroxide (H₂O₂) (10–40 mL/L), NiO nanoparticle (2.5–10 mg/L) and reaction time (15–90 min) and therefore, the influence of these factors were studied. Under optimum conditions (pH = 3, reaction time = 90 min, CEX = 40 mg/L, NiO = 7.5 mg/L and H₂O₂ = 30 mL/L) and using the US/H₂O₂/NiO process, the removal efficiencies of CEX, COD and TOC were 93.86%, 72.46% and 54.55%, respectively. The percentage contribution of each factor was also determined. Results introduced the solution pH as the most powerful factor, and its percentage contribution value was up to 94% in the studied process. It was also identified that the removal of CEX antibiotic using the hybrid process obeys the pseudo-first-order kinetics.     

Experimental study on CO2 hydrate formation in the presence of TiO2, SiO2, MWNTs nanoparticles

ABSTRACT

A series of experiments on CO₂ hydrate formation were carried out in the presence of titanium dioxide (TiO₂), silicon dioxide (SiO₂), multi-walled carbon nanotubes (MWNTs) nanoparticles. The effects of these nanoparticles on induction time, final gas consumption, and gas storage capacity have been investigated at the temperature of 274.15 K and the initial pressure of 5.0 MPa.g. The induction time of CO₂ hydrate formation was remarkably shortened to 12.5 min in the presence of 0.005 wt% MWNTs nanoparticles. The high thermal conductivity and heat capacity of MWNTs nanoparticles presented better heat transfer, and large surface area provided more suitable sites for heterogeneous nucleation of CO₂ hydrate.     

Ozone Production in a High Frequency Dielectric Barrier Discharge Generator

Factors that affect the performance of an expanded-mesh dielectric barrier discharge ozone cell were investigated. A gas feed pf 94% O₂, 4% Ar and 1% N₂ was used. An improvement in the productivity (g ozone/kWh) of about 20 % was achieved by doubling the gas flow rate through the cell. Decreasing the cell operating frequency (in the range 72 kHz to 19 kHz) increased the productivity of the ozone generator at constant power. The ozone production increased approximately in proportion to the input power; however productivity did not vary significantly with power above a minimum level. As the cell voltage was increased the dependence of productivity on power or frequency was reduced. Changing the feed gas temperature between ? 5^°C and + 42^°C had no effect on productivity. Finer meshes drew more power than coarser ones for a given voltage. Using a thinner mesh for the centre electrode increased productivity. The best results were obtained with a 6 × 3 × 1.86 mm titanium mesh giving a productivity of 110 g ozone/kWhr at 30–60 W, 1500–1900V and 23 KHz.     

Examining the Role of Effluent Organic Matter Components on the Decomposition of Ozone and Formation of Hydroxyl Radicals in Wastewater

The impact of wastewater derived effluent organic matter (EfOM) on the decomposition of ozone and formation of hydroxyl radicals (HO^●) was evaluated for four wastewaters (sites A, B, C1 and C2). The reactivity of EfOM was assessed by fractionation into four apparent molecular weight (AMW) fractions (<10 kDa, <5 kDa, <3 kDa, and <1 kDa). The R_CT, defined as the ratio of HO^● exposure to ozone exposure (∫HO^●dt?/?∫O₃dt), was measured for all fractions and bulk waters (at times greater than 5 seconds), with an initial ozone dose equal to the total carbon concentration of EfOM (ozone:DOC ratio of 1). The R_CT of all the samples and ozone first-order decay rates of two of the waters increased significantly (95% confidence) from the bulk sample to the <10 kDa fraction, and decreased with AMW. This indicates that the intrinsic capacity of different molecular weight fractions of the EfOM have different reactivity with ozone.     

A Strategy for Preparing Star Polymers Containing Metal–Metal Bonds Along the Polymeric Arms Using Click Chemistry

The [(η⁵-C₅H₄(CH₂)₃N₃)Mo(CO)₃]₂ dimer (3) was prepared and used to determine if the Huisgen cycloaddition reaction could be used to synthesize high molecular weight star polymers with metal–metal bonds in the arms. Several different click catalysts were examined. Cp*Ru(PPh₃)₂Cl (Cp* = η⁵-C₅(CH₃)₅) was previously shown to catalyze the formation of metal–metal bond-containing polymers using click chemistry; however, this catalyst underwent a Staudinger reaction with dimer 3 when a model coupling reaction was attempted with phenylacetylene. In order to avoid the Staudinger reaction, Cp*Ru(COD)Cl was used as the catalyst in the reaction of 3 with phenylacetylene, and coupling was observed after 14 h. Synthesis of a star polymer was attempted with 3 and 1,3,5-triethynylbenzene. Instead of coupling, Cp*Ru(COD)Cl reacted with the 1,3,5-triethynylbenzene. A third catalyst, Cu(IMes)Cl (IMes = 1,3-dimesityl-imidazol-2-ylidene) was used to couple 3 with 1,3,5-triethynylbenzene in 48 h. Both a high molecular weight polymer (M _n  = 77,000 g mol^?1) and a tripodal star core (M _n  = 1,800 g mol^?1) were successfully prepared with this catalyst.     

Effect of Ozone Treatment on the Reduction of Chlorpyrifos Residues in Fresh Lychee Fruits

The effect of ozone on the reduction of chlorpyrifos residue in lychee cv. Chakapat (Litchi chinensis Sonn.) was studied. Lychee fruits were dipped in the solution of chlorpyrifos at a concentration of 10 mg L^?1 for 10 min. Then, they were exposed to ozone gas (O₃) at concentrations of 80, 160, 200, 240 mg L^?1 and dipped in ozone-containing water, at concentrations of 2.2, 2.4, 3.4 and 3.2 mg. L^?1 for 10, 20, 30 and 60 min, respectively. Both ozone gas and ozone-containing water reduced pesticide residue in lychee, but exposure to ozone gas for 60 min was most effective. When lychee fruits were stored at 25 °C for 6 days, both processes did not show significant differences in weight loss, total soluble solids (TSS) and titratable acidity (TA). However, ozone-containing water decreased the eating quality of lychees after storage, compared with the ozone-fumigated groups.