Oxidant Concentration Research Articles

Efficient degradation of polyethylene (PE) plastics by a novel vacuum ultraviolet-activated periodate system: Operating parameters, by-products, and toxicity

This article presents a vacuum ultraviolet (VUV)-activated periodate (PI) system for the degradation of polyethylene (PE) plastics for the first time. The study compares the performance of the VUV/PI with VUV/sulfite, VUV/peroxymonosulfate, and VUV/persulfate degradation systems. At an oxidant concentration of 5mM, reaction time of 6h, PE plastics concentration of 0.1g/L, PE plastics size of 12mm, and pH 7, VUV/PI degradation system attained a mass loss ratio of 3.9%, which was higher than the other degradation systems. The mass loss ratio increased to 4.9% at pH 3, and 6.8% for a plastic size of 6mm. The degradation mechanism was found to involve iodate radicals and singlet oxygen as the main reactive species. Prolonging reaction time to 120h resulted in a mass loss percentage of 61.8%. SEM, FTIR, and water contact angle analyses after the degradation show cracks on PE plastics surface, an increase of carbonyl index, and a decrease of hydrophobicity affirming the efficient oxidation of PE plastics by the generated reactive species. The main oxidation by-products were alcohols, esters, acids, and ketones. Cytotoxicity and phytotoxicity analyses confirmed the efficient oxidation of PE plastics by the generated reactive species to result in low toxicity of the generated intermediates. The proposed study presents a simple and effective degradation system that can be implemented on a wider scale as a tertiary treatment in wastewater treatment plants for the degradation of plastics before release to the ecosystem.

MOF incorporated Polyethersulfone/Polylactic Acid ultrafiltration membranes for the catalytic removal of dyes via persulfate activation

This study synthesized novel nanocellulose/zeolitic Imidazolate Framework nanocomposite blended Polyethersulfone/Polylactic Acid (PES/PLA-CNF@ZIF-8) membranes through a modified phase inversion process. This is the first time that a nanocellulose-MOF composite catalytic nanomaterial has been synthesized and used as an additive in polymeric membranes. The morphology and chemical structure of the membranes and nanoparticles were characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) respectively. Membrane wettability and crystalline structure were characterised by contact angle, and X-ray diffraction (XRD) analysis respectively. CNF@ZIF-8 modified membranes showed improved contact angle which decreased from 76° in the pristine membranes to 40° in 2 wt% membranes, bulk porosity increased from 74.3.3 % to 81.06 % while the pure water flux increased from 208.30 Lm-2h−1 to 348.73 Lm-2h−1. Further, the modified membranes showed an increase in surface roughness reaching 84.14 nm in 2 wt% membranes. The synthesized membranes have been used as catalysts in the activation of persulfate to degrade Rhodamine B dye. The modified membranes displayed a high catalytic effect (>90 %) in activating persulfate to degrade RhB dye when compared to pristine membranes which showed a degradation efficiency of < 35 %. The study found that the optimum parameters for pH, membrane (catalyst) dosage, oxidant and initial dye concentration were 5, 0.3 g, 0.4 mM and 10 ppm respectively. Quenching experiments showed that •SO4- and •OH radicals were responsible for the dye degradation, with •SO4- radicals playing a major role in the oxidative degradation of the RhB dye. The synthesized membranes showed good stability when tested within five cycles, with the membranes showing degradation efficiency ranging from 92.1 % in the 1st cycle to 91.9 % in the 3rd cycle, before decreasing to 75.3 % in the 5th cycle. This study has therefore shown that the synthesized PES/PLA-CNF@ZIF-8 membranes have potential for use as catalysts in the degradation of cationic dyes in wastewater treatment through persulfate activation.

Two major deactivation mechanisms in carbon-based advanced oxidation processes (AOPs) dominated by electron-transfer pathway (ETP)

Carbon-based advanced oxidation processes through electron-transfer pathway are regarded as a green technology for efficient and selective oxidation of the emerging pollutants in complex water matrixes. Despite achievements in the superior activity and selectivity for organic degradation of carbocatalysts, their stabilities remain unsatisfactory, primarily because of the underexplored deactivation mechanisms. This study identifies two distinct deactivation mechanisms. The first is Oxidant Deactivation, due to overoxidation by the oxidant and predominantly affected by the concentration of oxidant. The other is Organic Deactivation, primarily caused by attachment of organic byproducts on catalyst surface, which reduces the overall oxidation potential of carbon/persulfate complex, instead of covering the surface “active sites”. Furthermore, the deactivation mechanisms mainly depend on intrinsic catalytic pathways: Oxidant Deactivation originates from the adjacent transfer pathway and Organic Deactivation from the electron shuttle pathway. Finally, the relationship between the deactivation mechanisms and carbon configuration (sp2/sp3) is revealed, and a catalyst with optimal activity and stability can be achieved through properly regulating the sp2/sp3 ratio. Results indicate that different protective strategies and application scenarios should be adopted for different systems to extend their lifespan in real wastewater treatment. This work sheds light on rational catalyst design toward advanced water purification systems with high efficiency and stability.

Exploring the Mechanism for the Photocatalytic Degradation of Oxytetracycline in Water using TiO2 and Supplementary Oxidants

The persistent presence of antibiotics in wastewater, exemplified by oxytetracycline (OTC), poses environmental risks, necessitating robust removal strategies. This study investigates the effectiveness of photocatalysis utilizing TiO2 (P25) treated at various temperatures, combined with different oxidants such as hydrogen peroxide (H2O2), potassium peroxydisulfate (PDS), potassium peroxomonosulfate (PMS) under diverse experimental conditions. The research systematically explores the impact of temperature, pH, and oxidant concentration on the efficiency of OTC degradation. Our findings reveal that the combination of P25/500, PDS, UV irradiation, and stirring demonstrates superior OTC degradation, surpassing 99% efficiency after 180 min. Optimal pH conditions are identified, emphasizing the importance of balancing acidity for enhanced performance. The study also provides insights into the optimal PDS concentration, indicating a threshold beyond which further increases yield diminishing returns. Mechanistic understanding is enhanced through scavenger experiments, elucidating the pivotal role of reactive oxygen species, particularly O2•−, in the photocatalytic process. This research offers a practical framework for TiO2-based photocatalysis in wastewater treatment, emphasizing tailored conditions for efficient antibiotic removal. The outcomes contribute valuable insights to the development of sustainable wastewater treatment protocols targeting antibiotic pollutants.

Calibrating the Oxidative Capacity of Microdroplets

AbstractRecently, redox chemical transformations have been reported to occur spontaneously in microdroplets. The origins of such novel reactivity are still debated, and any systematic correlation of the oxidative/reductive yield with the reactivity of the reactant is yet to be established. Towards this end, we report the simple, outer‐sphere, one‐electron oxidation of a series of ferrocene derivatives spanning a range of oxidation potentials from −0.1 V to +0.8 V vs. Ag/AgCl in acetonitrile microdroplets generated via nebulization and measured by mass spectrometry of the corresponding ferrocenium ions. The reaction environments and dynamics in the droplets are complex, and it is still unclear whether such reactivity correlates with any bulk thermodynamic values. Our key finding is that the ion yields decrease monotonically with the oxidation potential of the ferrocenes, which is a thermodynamic quantity. The ion yields emphatically do not obey the Nernstian ratio, revealing the redox processes in the droplets do not follow the assumptions of bulk steady‐state electrochemistry. Furthermore, oxidative competition in the mixture of several ferrocenes suggest a finite oxidative capacity or oxidant concentration. These results demonstrate that even though ion generation could be an out‐of‐equilibrium and kinetically limited process, the oxidative yield in microdroplets does correlate with thermodynamics, suggesting a possible free energy relationship between the kinetics and thermodynamics of the process.

Calibrating the Oxidative Capacity of Microdroplets.

Recently, redox chemical transformations have been reported to occur spontaneously in microdroplets. The origins of such novel reactivity are still debated, and any systematic correlation of the oxidative/reductive yield with the reactivity of the reactant is yet to be established. Towards this end, we report the simple, outer-sphere, one-electron oxidation of a series of ferrocene derivatives spanning a range of oxidation potentials from -0.1 V to +0.8 V vs. Ag/AgCl in acetonitrile microdroplets generated via nebulization and measured by mass spectrometry of the corresponding ferrocenium ions. The reaction environments and dynamics in the droplets are complex, and it is still unclear whether such reactivity correlates with any bulk thermodynamic values. Our key finding is that the ion yields decrease monotonically with the oxidation potential of the ferrocenes, which is a thermodynamic quantity. The ion yields emphatically do not obey the Nernstian ratio, revealing the redox processes in the droplets do not follow the assumptions of bulk steady-state electrochemistry. Furthermore, oxidative competition in the mixture of several ferrocenes suggest a finite oxidative capacity or oxidant concentration. These results demonstrate that even though ion generation could be an out-of-equilibrium and kinetically limited process, the oxidative yield in microdroplets does correlate with thermodynamics, suggesting a possible free energy relationship between the kinetics and thermodynamics of the process.

Integrating experimental and machine learning approaches for predictive analysis of photocatalytic hydrogen evolution using Cu/g-C3N4

This study addresses environmental issues like global warming and wastewater generation by exploring waste-to-energy strategies that produce renewable hydrogen and treat wastewater simultaneously. Cu/g-C3N4 is used to evolve hydrogen from sucrose solution and the impact of reaction parameters such as pH (3, 5, and 7), Cu loading (5, 10, and 15 wt%), catalyst amount (0.1, 0.2, and 0.3 g/L), and oxidant (H2O2) concentration (0, 10, and 20 mM) on the evolved hydrogen amount is examined. Characterization study confirmed successful incorporation of Cu without significantly altering g-C3N4 properties. The highest hydrogen production (1979.25 μmol g−1·h−1) is achieved with 0.3 g/L catalyst, 20 mM H2O2, 5 % Cu loading, and pH 3. The experimental study concludes that Cu/g-C3N4 is an effective photocatalyst for renewable hydrogen production. In addition to the experimental investigations, various machine learning (ML) models, including Random Forest, Decision Tree, XGBoost, among others, are employed to analyze the impact of reaction parameters and forecast the quantities of produced hydrogen. Alongside these individual models, an ensemble approach is proposed and utilized. The R2 values of these ML models ranged from 0.9454 to 0.9955, indicating strong predictive performance across the board. Additionally, these models exhibited low error rates, further confirming their reliability in predicting hydrogen evolution.

Investigation of the agricultural reuse potential of urban wastewater and other resources derived by using membrane bioreactor technology within the circular economy framework

The European Union, as delineated in Regulation (EU) 2020/741, sets forth minimum criteria for the reuse of wastewater. Directive 86/278/CEE sets the regulations for the reuse of sewage sludge in agriculture. This study aimed to investigate the treated water derived from a pilot plant situated in Granada, Spain, that utilizes membrane bioreactor technology to process real urban wastewater with the quality standards necessary for agricultural reuse. Additionally, the study evaluated the utilization potential of other resources generated during wastewater treatment, including biogas and biostabilized sludge. The pilot plant incorporated a membrane bioreactor featuring four ultrafiltration membranes operating continuously alongside a sludge treatment line operating in batch mode. The pilot plant operated during four cycles, each with distinct hydraulic retention times (6 h and 12 h) and variable mixed liquor-suspended solids concentrations (ranging from 2688 mg L−1 to 7542 mg L−1). During these cycles, the plant was doped with increasing concentrations of emerging contamination compounds (diclofenac, ibuprofen, and erythromycin) to test their effect on the resources derived from the treatment. Subsequently, a tertiary treatment involving an advanced oxidation process was applied to the different water lines, which left the wastewater treatment plant for a period of 30 min and utilized varying concentrations of oxidant. The results indicate that the effluent obtained meets the required quality standards for agricultural use. Therefore, there is potential to use this waste as a resource, which is in line with the principles of the circular economy. Furthermore, the other resources generated during the treatment process, such as the biogas produced during the digestion process and the biostabilized sludge, have the potential to be used as resources according to the circular economy indicators.

Effect of catalyst and oxidant concentrations in a TEMPO oxidation system on the production of cellulose nanofibers.

In traditional TEMPO oxidation systems, the high cost of TEMPO catalysts has been a significant barrier to the industrialization of oxidized CNF. From an economic perspective, presenting the characteristics of various CNFs produced with the oxidation systems with reduced catalyst usage could facilitate the industrial application of CNF across a wide range of fields. In this study, it was demonstrated that reducing the amount of TEMPO catalyst used (from 0.1 to 0.05 mmol g-1) in a conventional oxidation system increased the carboxylate content by approximately 6.3%. Furthermore, the activation of hydroxyl amine TEMPO, which is generated after the oxidation reaction of cellulose, was enhanced by adjusting the dosage of the inexpensive oxidant NaClO, leading to a 20% improvement in carboxylate content. This suggests that controlling the amount of NaClO as an oxidant can be a key parameter in adjusting the dosage of TEMPO to achieve the targeted degree of surface substitution. Results from the dispersion stability, UV-transmittance, and morphological properties of TEMPO-oxidized CNF using microfluidizing treatment showed that high carboxylate content plays a crucial role in producing high-purity CNF suspensions, which are small, uniform, and free from microfibers. Additionally, by varying the number of mechanical treatments applied to the oxidized cellulose, various types of CNF suspensions with different mean widths were obtained. We expect that these findings offer meaningful insights to end-users seeking a breakthrough in the performance limitations of final applications using cellulose nanomaterials.

Elimination of malachite green by modified Fenton like process. Application of Box Behnken design

&lt;p style="line-height:200%;text-align:justify;"&gt;&lt;span style="line-height:200%;" lang="EN-US"&gt;The aim of this work was to investigate an advanced oxidation process for removing malachite green from aqueous solutions using a modified Fenton-like process. An experimental Box-Behnken design was applied to determine the optimal conditions by examining the effects of catalyst concentration ([Fe&lt;sup&gt;2+&lt;/sup&gt;]), oxidant concentration ([K&lt;sub&gt;2&lt;/sub&gt;S&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;8&lt;/sub&gt;]), and stirring speed. The analysis of variance (ANOVA) indicated that oxidant concentration was the most significant factor, with a p-value of 0.001, while catalyst concentration, the quadratic term of the oxidant, and the interaction between catalyst concentration and stirring speed were also significant. The optimal conditions for maximum dye removal were found to be a catalyst concentration of 3.5 ppm, an oxidant concentration of 3.07 ppm, and a stirring speed of 200 rpm, achieving a theoretical degradation yield of 100% and an experimental yield of 98%. This agreement validates the model and the importance of the optimized parameters. Additionally, degradation kinetics studies in various natural waters revealed that oxidation efficiency followed this order: Distilled water (98%) &amp;gt; Seawater ≈ Industrial water (88.97%) &amp;gt; Source water (85.57%) &amp;gt; Mineral water (80.52%).&lt;/span&gt;&lt;/p&gt;

Kinetic Modelling of Aromaticity and Colour Changes during the Degradation of Sulfamethoxazole Using Photo-Fenton Technology

Sulfamethoxazole (SMX) is an antibiotic that is extensively used in veterinary medicine, and its occurrence in wastewater and surface water can reach up to 20 μg/L. SMX is categorized as a pollutant of emerging concern by the US EPA due to its persistence and effects on humans and the environment. In this study, photo-Fenton technology is proposed for the removal of SMX. Aqueous solutions of SMX (50.0 mg/L) are treated in a 150 W UV photoreactor, using [Fe2+]0 = 0.5 mg/L and varying [H2O2]0 = 0–3.0 mM. During the reaction, colour (AU) was assessed along with SMX (mg/L), turbidity (NTU), and TC (mg/L). SMX degrades to aromatic intermediates with chromophoric groups, exhibiting colour (yellow to brown) and turbidity. As these intermediates are mineralized into CO2 and H2O, the colour and turbidity of the water lose intensity. Using a molar ratio of 1 mol SMX:10 mol H2O2, the maximum degradation of aromatic species takes place (71% elimination), and colourless water with turbidity &lt; 1 NTU is obtained. A kinetic modelling for aromaticity loss and colour formation as a function of the oxidant concentration has been proposed. The application of this model allows the estimation of oxidant amounts for an efficient removal of SMX under environmentally friendly conditions.

Solvolysis and oxidative liquefaction of the end-of-life composite wastes as an element of the circular economy assumptions

In pursuit of sustainable development, recycling composite waste is a crucial challenge as well as an opportunity to support the progress towards eco-friendly materials management and circular economy practices. The current study brings together two modern recycling techniques solvolysis and oxidative liquefaction to recycle five types of composite waste materials including wind turbine blades (WTBs), composite pipes, personal protective equipment (PPEs) used in the medical sector, photovoltaic (PV) panels and municipal solid waste (MSW). Following a well-structured experimental design for each type of waste the solvolysis was performed at a temperature range of 100–190 °C, process time within the range of 1–3 h, and catalyst (TBD) concentration within the range of 0.015–0.025 mol, end with ethylene glycol and 1-methyl-2-pyrrolidinone in a 1:1 M ratio, while depending on the material evaluated, the oxidative liquefaction process was conducted at temperatures between 250 and 350 °C for WTB and between 200 and 300 °C for PPE, MSW, and PV. Oxidant concentrations, reaction time and pressure (15–45%, 30–90 min, 20–40 bar for WTBs, 30–60%, 45 min, 30 bar for remaining waste types) were studied in addition to highly variant waste-to-liquid ratio from 5 to 25% for WTB, 3–7% for PPE and MSW, and 12.5–37.5 for PV. Prior to experimental investigation, surface morphologies and chemical studies of the waste material were performed by scanning electron microscope (SEM) and Fourier transform infrared FT-IR spectroscopy, while after experimentation total polymer degradation (TPD) was calculated and liquid products were analysed through gas chromatography with flame ionisation detection (GC-FID). Following the solvolysis, 50–60% TPD was obtained, allowing for the recovery of glass fibres (GF) with average lengths of 50–60 mm and a maximum length of 650 mm. This allowed for the recovery of GFs with average lengths of 50–60 mm and a maximum length of 650 mm. In the case of oxidative liquefaction, total polymer degradation of 72–100%, 52–100% and 55–100% was achieved, depending on the investigated waste, i.e. WTB, PPE and MSW, respectively. The yield of oxygenated chemical compounds depended upon the types and composition of waste, but acetic acid was the main acid while WTB, PPE, and MSW, the liquid samples contained phenol also. Involved chemistry and possible degradation pathways of complex composite wastes are discussed in detail to enhance the recycling process and material recovery.

The Protective Effects of Methionine on Nickel-Induced Oxidative Stress via NF-κB Pathway in the Kidneys of Mice.

Nickel (Ni) is a human carcinogen that causes oxidative damage to many organs, and methionine has been studied to protect mammals from similar toxic effects by other heavy metals possibly through sulfur metabolism. This study aimed to investigate the protective effects of methionine on Ni-induced injuries to the kidneys. In this study, the mice were randomly divided into BC (normal diet), MD (methionine deficiency diet), MN (methionine plus nickel diet), and MDN (methionine deficiency plus nickel diet) treatment groups. Their renal function, histological changes, cell cycle, apoptosis, oxidative damage, and NF-κB inflammatory cytokines were detected after 21days by HE, immunohistochemistry, TUNEL staining, and biochemical and ELISA methods. The results showed that serum Cr, BUN, and the NAG content increased in MDN (P < 0.01), MN (P < 0.05), and MD (P < 0.05) group mice compared to BC group mice. Glomerulus atrophy and renal tubular atrophy were observed in the MDN, MN, and MD groups but less severe in MN group mice. The PCNA protein content was the highest in BC group mice followed by MD, MN, and MDN. The activities of antioxidant enzymes (SOD, CAT, GSH, GSH-Px, and GSH-ST) were lower significantly in MD, MN, and MDN group mice, and the oxidant products content (MDA, LPO, and ROS) in the BC group were higher than those in other groups with a similar trend. The contents of NF-κB, TNF-α, IFN-γ, IL-1a, and IL-6 in the BC group were found to increase significantly in MD, MN, and MDN groups. In conclusion, Ni-induced kidney injury was indicated by renal tissue and cell damage, increased kidney metabolism products release in the serum, and renal oxidative stress while methionine addition helped alleviate the injury. In addition, the NF-κB signal pathway was involved in the renal inflammatory reaction induced by Ni where methionine helped mitigate it.

Star-Like Polypeptides as Simplified Analogues of Horseradish Peroxidase (HRP) Metalloenzymes.

Peroxidases, like horseradish peroxidase (HRP), are heme metalloenzymes that are powerful biocatalysts for various oxidation reactions. By using simple grafting-from approach, ring-opening polymerization (ROP), and manganese porphyrins, star-shaped polypeptides analogues of HRP capable of catalyzing oxidation reactions with H2O2 is successfully prepared. Like their protein model, these simplified analogues show interesting Michaelis-Menten constant (KM) in the mM range for the oxidant. Interestingly, the polymer structures are more resistant to denaturation (heat, proteolysis and oxidant concentration) than HRP, opening up interesting prospects for their use in catalysis or in biosensing devices.

Investigating the role of photochemistry and impact of regional and local contributions on gaseous pollutant concentrations (NO, NO2, O3, CO, and SO2) at urban and suburban sites

Gaseous pollutant concentrations were monitored for one year in urban (NO, NO2, O3, CO, and SO2) and suburban (NO, NO2, and O3) sites. Common characteristics were identified at both sites, such as higher concentrations during typical winter months for all pollutants except O3. Increased NO, NO2, CO and SO2 concentrations during wintertime were linked to residential heating emissions, with pairwise correlations showing CO as marker for the study site. O3 production was lower in wintertime but higher in summertime at both sites based on its seasonal cycle and the impact of sunlight. Furthermore, diurnal variations showed that traffic emissions during rush hours most profoundly affected CO and NO. Nevertheless, NOx were characteristically higher at the urban site based on the burdened environment, whereas O3 was higher at the suburban site due to the lower destruction rates. O3 was the dominant oxidant at both sites, with a linear regression between OX and NOx revealing a negative relationship. This observation suggested a dominant regional contribution to oxidant concentrations. In addition, abnormally high O3 concentrations in relation to the season were reported for the first time at the study sites. Elevated concentrations were measured in parallel with Sahara dust events indicating noteworthy atmospheric conditions that require further assessment. Other O3 burdened periods were driven by regional transport of polluted plumes from the northeast. Lastly, nocturnal increases in O3 were observed and associated with enhanced vertical mixing.

Analysis of the mechanisms underlying the anticancer and biological activity of retinoic acid and chitosan nanoparticles containing retinoic acid.

Retinoic acid (RA) has been shown in earlier investigations to have anticancer properties in various cancer cells. RA's effect on breast cancer treatment remains uncertain, though. This study investigated whether RA and chitosan nanoparticles (NPs) loaded with RA could be harmful to the MCF-7 cell line. In this study, NPs with RA were used in characterization tests. Using ELISA kits, the amounts of 8-okso-2'-deoksiguanozin (8-oxo-dG), BCL-2, Bcl-2-Associated X-protein (Bax), cleaved Poly (ADP-ribose) polymerases (PARP), total oxidant and antioxidant, and cleaved caspase-3 capacities were determined. The analysis of chitosan NPs showed that their drug-release profile, encapsulation efficiency (EE), and particle size were suitable for cell culture experiment. The EE value of NPs including RA was calculated as 83.32 ± 0.04%. The IC50 value for RA was 2.89 ± 0.03µg/mL, while the IC50 value for RA-loaded NPs was significantly lower at 2.28 ± 0.02µg/mL. In ELISA testing, RA and chitosan NPs containing RA at a concentration of 2µg/mL dramatically increased the concentrations of total oxidant, cleaved caspase-3. Cleaved caspase-3 levels were quantified as 614.90 ± 3.40pg/mg protein in the control group, 826.37 ± 5.82pg/mg protein in RA-treated cells, and 863.52 ± 4.32pg/mg protein in RA-NP-treated cells. Interestingly, no substantial variations were observed in the levels of the anti-apoptotic protein BCL-2. Overall, studies revealed that RA and RA-NPs promoted apoptosis in MCF-7 cells by upregulating the expression of pro-apoptotic proteins Bax, cleaved caspase-3, and cleaved PARP.

Green synthesis of magnetic graphene-like biochar with oxygen vacancies for efficient adsorption and degradation of emerging antivirals from water

In this research, a magnetic biochar derived from the Vicia ervilia plant and possessing graphene-like properties (BC-G/Fe3O4) was used along with the activator persulfate for the adsorption and degradation of emerging pollutants such as Remdesivir and Favipiravir. The morphology, specific surface area, graphitization degree, and surface chemistry properties of the composite were determined using various techniques. The results showed that the synthesized BC-G/Fe3O4 had a high SSA (506.556 m2/g), indicating its suitable adsorption properties for the removal of antiviral drugs. The impact of various factors on the adsorption-oxidation process, including pH, catalyst dosage, oxidant concentration, antiviral concentration, and temperature, was examined and optimized through the utilization of response surface methodology and central composite design. The highest removal percentage of Remdesivir (93 %) and Favipiravir (98 %) was achieved at an initial antiviral concentration of 125 mg/L, catalyst dosage of 7 mg for Remdesivir and 5 mg for Favipiravir, contact time of 120 min, and pH of 7. Through the implementation of radical scavenging experiments, a thorough understanding of the mechanisms involved in PMS activation and the degradation of Favipiravir and Remdesivir was attained. The findings of this study indicate that the BC-G/Fe3O4 catalyst possesses excellent biocompatibility, adsorption-degradation capabilities, and reusability. Consequently, it can be successfully employed to eliminate emerging pollutants from aquatic environments.

So, you cannot vent: A deep dive into other explosion protection methods

AbstractCurrent NFPA standards for managing combustible dust hazards require equipment with an explosion hazard to be protected from the effects of deflagration. These protections include deflagration venting in accordance with NFPA 68, Standard on Explosion Protection by Deflagration Venting, 2023 Edition, or oxidant concentration reduction, combustible concentration reduction, deflagration suppression, or deflagration pressure containment, via NFPA 69, Standard on Explosion Protection Systems, 2024 Edition. It makes sense to choose the simplest and most cost‐effective option based on the inherent design and risk of the operation. Implementation of any one of these protection methods requires an understanding of the method and all the associated requirements. While the basic methods are fairly straightforward, the associated requirements are often less understood. In this paper, the author will introduce the basic methods and take a deep dive into the associated requirements of each method of protection. Based on the author's experience in evaluating protection systems, common misunderstandings will be highlighted, for example, the margin of safety to apply and the operational limits required to be developed and documented for oxidant concentration reduction systems.

A comprehensive evaluation of enhanced temperature influence on gas and aerosol chemistry in the lamp-enclosed oxidation flow reactor (OFR) system

Abstract. Oxidation flow reactors (OFRs) have been extensively utilized to examine the formation of secondary organic aerosol (SOA). However, the UV lamps typically employed to initiate the photochemistry in OFRs can result in an elevated reactor temperature when their implications are not thoroughly evaluated. In this study, we conducted a comprehensive investigation into the temperature distribution within an Aerodyne potential aerosol mass OFR (PAM-OFR) and then examined the subsequent effects on flow and chemistry due to lamp heating. A lamp-induced temperature increase was observed, which was a function of lamp-driving voltage, number of lamps, lamp types, OFR residence time, and positions within the PAM-OFR. Under typical PAM-OFR operational conditions (e.g., &lt; 5 d of equivalent atmospheric OH exposure under low-NOx conditions), the temperature increase typically ranged from 1–5 °C. Under extreme (but less frequently encountered) conditions, the heating could reach up to 15 °C. The influences of the increased temperature over ambient conditions on the flow distribution, gas, and condensed-phase chemistry within PAM-OFR were evaluated. Our findings indicate that the increase in temperature altered the flow field, resulting in a diminished tail on the residence time distribution and corresponding oxidant exposure due to faster recirculation. According to simulation results from a radical chemistry box model, the variation in absolute oxidant concentration within PAM-OFR due to temperature increase was minimal (&lt; 5 %). The temperature influences on seed organic aerosol (OA) and newly formed secondary OA were also investigated, suggesting that an increase in temperature can impact the yield, size, and oxidation levels of representative biogenic and anthropogenic SOA types. Recommendations for temperature-dependent SOA yield corrections and PAM-OFR operating protocols that mitigate lamp-induced temperature enhancement and fluctuations are presented. We recommend blowing air around the reactor's exterior with fans during PAM-OFR experiments to minimize the temperature increase within PAM-OFR. Temperature increases are substantially lower for OFRs utilizing less powerful lamps compared to the Aerodyne version.

Machine learning predict the degradation efficiency of aqueous refractory organic pollutants by ultrasound-based advanced oxidation processes

Ultrasound based advanced oxidation processes (AOPs) are effective for removing refractory organic pollutants by generating reactive species. Machine learning (ML) can systematically provide an excellent opportunity to determine the relationship between feature variables and output variables through large amounts of data, thereby reducing the need for experimental measurements. In this study, a ML approach was applied for the first time to predict the degradation efficiency of aqueous refractory organic pollutants by ultrasound-based AOPs. The obtained dataset was normalized and introduced into four ML models. Among them, Random Forest Regressor and XGB Regressor models had the best fit with 0.9546 and 0.9749 for training set R2 and 0.9548 and 0.9740 for test set R2, respectively. Relative importance analysis and SHAP analysis showed that catalyst type, oxidant concentration, reaction time, and catalyst dosage are the important variables affecting the degradation efficiency of refractory organic pollutants. In addition, excessive ultrasonic intensity, ultrasonic frequency, oxidant concentration, and catalyst dosage had little effect on the increase of degradation efficiency. Based on the descriptive data analysis, high degradation efficiency was obtained with ultrasonic intensity of 2 W·mL−1, ultrasonic frequency of 20–40 kHz, reaction time of 60–90 min, pH 3–7, oxidant concentration of ∼7.5 mmol·L−1, and catalyst dosage of >0.4 g·L−1. This work demonstrated a new predictive method to understand the comprehensive influence of operative factors on degradation efficiency in US-based AOPs, guiding parameter and process optimization.