Analysis of Ozonation Processes Using Coupled Modeling of Fluid Dynamics, Mass Transfer, and Chemical Reaction Kinetics

Unveiling the potential of machine learning in cost-effective degradation of pharmaceutically active compounds: A stirred photo-reactor study

In this study, neural networks and support vector regression (SVR) were employed to predict the degradation over three pharmaceutically active compounds (PhACs): Ibuprofen (IBP), diclofenac (DCF), and caffeine (CAF) within a stirred reactor featuring a flotation cell with two non-concentric ultraviolet lamps. A total of 438 datapoints were collected from published works and distributed into 70% training and 30% test datasets while cross-validation was utilized to assess the training reliability. The models incorporated 15 input variables concerning reaction kinetics, molecular properties, hydrodynamic information, presence of radiation, and catalytic properties. It was observed that the Support Vector Regression (SVR) presented a poor performance as the ε hyperparameter ignored large error over low concentration levels. Meanwhile, the Artificial Neural Networks (ANN) model was able to provide rough estimations on the expected degradation of the pollutants without requiring information regarding reaction rate constants. The multi-objective optimization analysis suggested a leading role due to ozone kinetic for a rapid degradation of the contaminants and most of the results required intensification with hydrogen peroxide and Fenton process. Although both models were affected by accuracy limitations, this work provided a lightweight model to evaluate different Advanced Oxidation Processes (AOPs) by providing general information regarding the process operational conditions as well as know molecular and catalytic properties.

Performance evaluation and optimization of a suspension-type reactor for use in heterogeneous catalytic ozonation

Packed fixed-bed reactors are traditionally used for heterogeneous catalytic ozonation. However, a high solid-to-liquid requirement, poor ozone dissolution, ineffective utilization of catalyst surface area, and production of large amounts of catalyst waste impede application of such reactors. In this study, we designed a suspension catalytic ozonation reactor and compared the performance of this reactor with that of a traditional fixed-bed catalytic ozonation reactor employing oxalic acid (OA) as the target contaminant. Our results showed that total O3 dissolved into the suspension reactor (117-134 mg.L-1) was much higher compared to that measured in the fixed-bed reactor (53 mg.L-1) due to a higher O3(g) interphase mass transfer rate in the suspension reactor. In accordance with the higher O3(g) interphase mass transfer, we observed a much higher proportional OA removal (32 %) compared to that achieved in the fixed-bed reactor (10%) employing an Fe-oxide catalyst supported on Al2O3 (Fe-oxide@Al2O3) in both reactors. Use of a double-layered Cu-Al hydroxide (Cu-Al LDHs) catalyst in the suspension reactor further enhanced the performance with nearly 90 % OA removal observed. Given the superior performance of the suspension reactor, we investigated the impact of operating conditions (catalyst dosage, hydraulic retention time and ozone dosage) employing Cu-Al LDHs as the catalyst. We also developed a mathematical kinetic model to describe the performance of the suspension reactor and, through use of the kinetic model, showed that O3(g) interphase transfer rate was the rate-limiting step in OA removal. Thus, improvement in ozone gas diffuser design is required to improve the performance of the suspension reactor. Overall, the present study demonstrated that suspension reactors were more effective than fixed-bed reactors for oxidation of surface-active organic compounds such as OA due to the higher ozone interphase mass transfer rate and effective utilization of the catalyst surface area that can be achieved. As such, further research on suspension reactor design and development of catalysts suitable for use in suspension reactors should facilitate large-scale application of catalytic ozonation processes by the wastewater treatment industry.

Kinetic modelling assisted balancing of organic pollutant removal and bromate formation during peroxone treatment of bromide-containing waters

The peroxone process (O3/H2O2) is reported to be a more effective process than the ozonation process due to an increased rate of generation of hydroxyl radicals (•OH) and inhibition of bromate (BrO3-) formation which is otherwise formed on ozonation of bromide containing waters. However, the trade-off between the H2O2 dosage required for minimization of BrO3- formation and effective pollutant removal has not been clearly delineated. In this study, employing experimental investigations as well as chemical modelling, we show that the concentration of H2O2 required to achieve maximum pollutant removal may not be the same as that required for minimization of BrO3- formation. At the H2O2 dosage required to minimize BrO3- formation (<10 µg/L), only pollutants with high to moderate reactivity towards O3 and •OH are effectively removed. For pollutants with low reactivity towards O3/•OH, high O3 (O3:DOC>>1 g/g) and high H2O2 dosages (O3:H2O2 ∼1 (g/g)) are required for minimizing BrO3- formation along with effective pollutant removal which may result in a very high residual of H2O2 in the effluent, causing secondary pollution. On balance, we conclude that the peroxone process is not effective for the removal of low reactivity micropollutants if minimization of BrO3- formation is also required.

Revisit the Role of Salinity in Heterogeneous Catalytic Ozonation: The Trade-Off between Reaction Inhibition and Mass Transfer Enhancement

Heterogeneous catalytic ozonation (HCO) is an effective technology for advanced wastewater treatment, while the influence of coexisting salts remains unclear and controversial. Here, we systematically explored the influence of NaCl salinity on the reaction and mass transfer of HCO through lab experiments, kinetic simulation, and computational fluid dynamics modeling, and proposed that the trade-off between reaction inhibition and mass transfer enhancement would affect the pollutants degradation pattern under varying salinity. The increase of NaCl salinity decreased ozone solubility and accelerated the futile consumption of ozone and hydroxyl radicals (•OH), and the maximum •OH concentration under 50 g/L salinity was only 23% of that without salinity. However, the increase of NaCl salinity also significantly reduced the ozone bubble size and enhanced the interphase and intraliquid mass transfer, with the volumetric mass transfer coefficient being 130% higher than that without salinity. The trade-off between reaction inhibition and mass transfer enhancement shifted under different pH values and aerator pore sizes, and the oxalate degradation pattern would change correspondingly. Besides, the trade-off was also identified for Na2SO4 salinity. These results emphasized the dual influence of salinity and offered a new theoretical perspective on the role of salinity in the HCO process.

The Biological and Molecular Action of Ozone and Its Derivatives: State-of-the-Art, Enhanced Scenarios, and Quality Insights

The ultimate objective of this review is to encourage a multi-disciplinary and integrated methodological approach that, starting from the recognition of some current uncertainties, helps to deepen the molecular bases of ozone treatment effects on human and animal well-being and to optimize their performance in terms of reproducibility of results, quality, and safety. In fact, the common therapeutic treatments are normally documented by healthcare professionals' prescriptions. The same applies to medicinal gases (whose uses are based on their pharmacological effects) that are intended for patients for treatment, diagnostic, or preventive purposes and that have been produced and inspected in accordance with good manufacturing practices and pharmacopoeia monographs. On the contrary, it is the responsibility of healthcare professionals, who thoughtfully choose to use ozone as a medicinal product, to achieve the following objectives: (i) to understand the molecular basis of the mechanism of action; (ii) to adjust the treatment according to the clinical responses obtained in accordance with the principles of precision medicine and personalized therapy; (iii) to ensure all quality standards.

Analysis of second grade hybrid nanofluid flow over a stretching flat plate in the presence of activation energy

The research of fluid containing nanoparticles for the heat transport characteristics is very famous because of its variety of real-life applications in various thermal systems. Although the thermal efficiency of the nanofluid was effective but still the nano scientists were trying to introduce some new advance class of fluid. Therefore, an advance class of fluid is developed by the dispersion of two different nano sized particles in the conventional base fluid known as "Hybrid nanofluid" which is more effective compared to simple nanofluids in many engineering and industrial applications. Therefore, motivated from the hybrid type of nanofluids in the current research we have taken two-dimensional laminar and steady flow of second grade fluid passing through porous plate. The engine oil base fluid is widely used fluid in the engineering and industrial problems. Keeping these applications in mind the engine oil is considered and two different nanoparticles Copper and aluminum oxide are added in ordered to get the required thermal characteristics. In addition to this the thermal radiation, chemical reaction, activation energy, Brownian motion and thermophoresis are also addressed during the current research. The present proposed higher-order PDE's is transformed to the non-linear system of ODE's. For the solution of the proposed high non-linear model HAM method is employed. As the hybrid nanofluid are highlighted on the second-grade fluid flow over a horizontal porous flat plate. During the present analysis and experimental study, it has been proved that the performance of hybrid nanofluid is efficient in many situations compared to nanofluid and regular fluid. For physical interpretation all the flow parameters are discussed through graphs. The impact of volume fraction is also addressed through graphs. Moreover, the comparative analysis between hybrid and nanofluid is carried out and found that hybrid nanofluid performed well as compared to nanofluid and regular fluid. The engineering quantities obtained from the present research have been presented in tables.