Mol Of H2O2 Research Articles

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 < 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.

Polypropylene Packaged Ten Days Cold Stored Rose Cut Flowers cv. Bordeaux Influenced by Different Pulsing Solution

The study included different pulsing solution viz., water, HQC 200mg/l, sucrose 50g/l + HQC 200 mg/l, citric acid 200mg/l, α-lipoic acid 200mg/l, GA3 100 mg/l and BA 100mg/l to study the effect on flower quality and vase life of PP (polypropylene) packaged cold storage (at 2°C) rose cv. Bordeaux, for the period of 10 days. Pre-storage pulsing of GA3 100mg/l solution treatment showed highly promising results in extending flowers vase life along with maintained flower quality just after storage and at 4th DAS in vase life. Further, GA3 100mg/l solution treatment recorded significantly higher water up take (175.65 ml), change in fresh weight (10.50%) at 4th DAS, total dissolve solids (8.85 °brix, 8.05 °brix and 6.75 °brix) and membrane stability index (81.97 %, 65.97 % and 37.88 %) at 2nd, 4th and 6th DAS. Moreover, it was evident from the results that same treatment recoded significantly higher total soluble sugar (59.65 mg/g fresh weight), Estimated protein (18.79 mg/g fresh weight), catalase activity (20.42 µ mol H2O2 min-1 g-1 protein), peroxidation activity (40.30 µ mol H2O2 min-1 g-1 protein), pigment content (15.82 mg/g fresh weight) anthocyanin content in the petals at 4th DAS. Whereas, GA3 100 mg/l pulsing solution treated PP packaged cold stored rose cut flowers cv. Bordeaux recorded significantly higher vase life (6.88 days) which was at par with treatment P2 (Sucrose 50 g/l + HQC 200 mg/l).

Chemiluminescence "Add-and-Measure" Sensing Paper Based on the Prussian Blue/Metal-Organic Framework MIL-101 Nanozyme for Rapid Hydrogen Peroxide Detection.

In this work, a chemiluminescent sensing paper has been developed using a peroxidase biomimetic metal-organic framework as a versatile host platform. For the first time, we have explored the use of in situ growth of Prussian Blue nanoparticles (PB-NPs) onto the MIL-101(Fe) structure for the assembly of a ready-to-use sensing paper. In situ growth of PB-NPs has been performed on the surface of the MIL-101(n) family. This novel composite, named PB-NPs@MIL-101(Fe), has been successfully used to develop a sensing paper for one-step detection of H2O2 in real samples (commercial disinfectant solutions and tap water samples). The as-prepared material was fully characterized, including X-ray analysis, Fourier transform infrared, scanning and transmission electron microscopies, nitrogen isotherms, and elemental analysis. After the characterization, the analytical performance of the PB-NPs@MIL-101(Fe) sensing paper was evaluated. The low-cost sensor (0.15 euro per unit) was able to detect down to 8.2 μM (corresponding to 8.2 × 10-11 mol) H2O2 using only 10 μL of sample with satisfactory reproducibility (relative standard deviation 17%).

Computational investigation of combustion and emission characteristics of HCCI engine fueled with Carbon-Free NH3 –H2O2 blend

A computational investigation is provided of the utilization of blends of NH3 and H2O2 as carbonless fuels for HCCI combustion. A Computational Fluid Dynamics (CFD) model is developed and validated to assess the engine’s performance under varying proportions of NH3 and H2O2, equivalence ratios, and inlet temperatures. The heat release rate profiles demonstrated dual peaks, which were rationalized as an initial fuel decomposition followed by a slow thermal explosion and then a fast depletion of the fuel after the generation of a pool of OH radicals through decomposition of H2O2. Findings suggest that an increase in mole fraction of H2O2 advances combustion. Increasing the H2O2 volume fraction also decreases combustion duration, while increasing the IMEP. In-cylinder peak pressure and Maximum Pressure Rise Rate (MPRR) increase with H2O2 mole fraction, leading to reduced thermal efficiency, particularly at higher equivalence ratios, and an increased danger of uncontrolled combustion (knocking). Additionally, higher inlet mixture temperatures were shown to result in an advancement in the start of combustion and a reduction in combustion duration, with a corresponding increase in peak pressure. This points to the possibility of potentially controlling the notoriously difficult-to-control HCCI combustion through intake temperature for NH3/H2O2 fuel blends. However, increased NOx emissions are observed for increased intake temperature and in any case the NOx emissions are orders of magnitude above current regulatory limits, which means that practical engine operation will only be possible with an aftertreatment scheme based on the de-NOx activity of NH3.

Bi-reforming of model biogas to syngas over ultrasmall Ru/MgO nano-catalysts prepared via soft template-assisted mechanochemical method

The upgrading of renewable biogas into value-added fuel and chemicals via syngas is of great significance. Ru/MgO nano-catalysts were prepared via novel soft template-assisted mechanochemical method. Comprehensive characterizations (XRD, N2 physisorption, ICP-OES, CO-chemisorption, CO2-TPD, XPS, HAADF-STEM, HRTEM, CH4-TPSR/CO2-TPO, TGA and Raman spectroscopy, etc.) were conducted to deeply analyze the fresh/spent catalysts. The 0.2Ru/MgO-0.2CTAB catalyst showed high initial activity in terms of CH4/CO2 conversion (∼94 %/61 %) and maintained catalytic stability over 120 h in bi-reforming of model biogas, at 800 °C under CH4/CO2/N2/H2O molar ratio of 3:2:1:2.6 and weight hourly space velocity of 30960 mL g-1h−1. CTAB and other soft templates were effective in enhancing the dispersion of Ru nanoparticles (NPs), which contribute to the inhibition of the deep cracking of CH4 and coke accumulation. Alkaline MgO oxide was crucial in the activation of CO2 and the production of active O* species, thus promoting the removal of carbonaceous precursor and inhibiting the coke accumulation. Additionally, the strong interaction between ultrafine Ru NPs and the MgO support significantly contributed to its anti-sintering performance. The combined advantages of narrow size distribution of ultra-small Ru NPs, suitable basicity of MgO as well as the interaction between ultrafine Ru NPs and MgO over 0.2Ru/MgO-0.2CTAB catalyst led to satisfying catalytic performance in bi-reforming of model biogas.

A new colorimetric lactate biosensor based on CUPRAC reagent using binary enzyme (lactate-pyruvate oxidases)-immobilized silanized magnetite nanoparticles

A novel optical lactate biosensor is presented that utilizes a colorimetric interaction between H2O2 liberated by a binary enzymatic reaction and bis(neocuproine)copper(II) complex ([Cu(Nc)2]2+) known as CUPRAC (cupric reducing antioxidant capacity) reagent. In the first step, lactate oxidase (LOx) and pyruvate oxidase (POx) were separately immobilized on silanized magnetite nanoparticles (SiO2@Fe3O4 NPs), and thus, 2 mol of H2O2 was released per 1 mol of the substrate due to a sequential enzymatic reaction of the mixture of LOx-SiO2@Fe3O4 and POx-SiO2@Fe3O4 NPs with lactate and pyruvate, respectively. In the second step, the absorbance at 450 nm of the yellow-orange [Cu(Nc)2]+ complex formed through the color reaction of enzymatically produced H2O2 with [Cu(Nc)2]2+ was recorded. The results indicate that the developed colorimetric binary enzymatic biosensor exhibits a broad linear range of response between 0.5 and 50.0 µM for lactate under optimal conditions with a detection limit of 0.17 µM. The fabricated biosensor did not respond to other saccharides, while the positive interferences of certain reducing compounds such as dopamine, ascorbic acid, and uric acid were minimized through their oxidative removal with a pre-oxidant (NaBiO3) before enzymatic and colorimetric reactions. The fabricated optical biosensor was applied to various samples such as artificial blood, artificial/real sweat, and cow milk. The high recovery values (close to 100%) achieved for lactate-spiked samples indicate an acceptable accuracy of this colorimetric biosensor in the determination of lactate in real samples. Due to the increase in H2O2 production with the bienzymatic lactate sensor, the proposed method displays double-fold sensitivity relative to monoenzymatic biosensors and involves a neat color reaction with cupric-neocuproine having a clear stoichiometry as opposed to the rather indefinite stoichiometry of analogous redox dye methods.Graphical

Fourier Transform Infrared Spectroscopy and the Physicochemical Properties of Modified Plukenetia Conophora and Thevetia Peruviana Seed Oils for Lubricant Purposes

Recently, there have been diversion of attention from lubricant from fossil sources to biolubricants due to its effect on the environment and human life. Vegetable oils have found usefulness in the production of biolubricant but have some drawbacks. In other to mitigate this problems, Plukenetia conophora (PKCO) and Thevetia peruviana (TVTO) seed oils were chemically modified via epoxidation, hydroxylation, and acetylation. Epoxidation was done using glacial acetic acid (0.05mol of acid: 1 mol C=C; Amberlite IR – 120H ion exchange resin; 1.5mol H2O2: 1 mol C=C) at 65oC for both PKCO and TVTO. The hydroxylation reactions were done at room temperature (97% formic acid; 30% H2O2) for 12hr. Acetylation from epoxidation was also carried out. Reactions were monitored by FTIR spectroscopy, and the physicochemical and lubricant properties investigated. The bands at 925-820cm-1 confirms the presence of epoxy group in EPPKCO and EPTVTO. The band at 3450–3430cm-1 indicate the hydroxyl group in both PKCO-OH and TVTO-OH. It also confirms hydroxyl acetal formation. EPPKCO has proven to be the best candidate for biolubricant formulation based on the physicochemical and lubricant properties, whereas the peroxide value must be improved using appropriate additives.

Computing solubility and thermodynamic properties of H2O2 in water

Hydrogen peroxide plays a key role in many environmental and industrial chemical processes. We performed classical Molecular Dynamics and Continuous Fractional Component Monte Carlo simulations to calculate thermodynamic properties of H2O2 in aqueous solutions. The quality of the available force fields for H2O2 developed by Orabi and English (2018) [67], and by Cordeiro (2014) [69] was systematically evaluated. To assess which water force field is suitable for predicting properties of H2O2 in aqueous solutions, four widely used water force fields were used, namely the TIP3P, TIP4P/2005, TIP5P-E, and a modified TIP3P force field. While the computed densities of pure H2O2 in the temperature range of 253 - 353 K using the force field by Orabi & English are in excellent agreement with experimental results, the densities using the force field by Cordeiro are underestimated by 3%. The TIP4P/2005 force field in combination with the H2O2 force field developed by Orabi & English can predict the densities of H2O2 aqueous solution for the whole range of H2O2 mole fractions in very good agreement with experimental results. The TIP4P/2005 force field in combination with either of the H2O2 force fields can predict the viscosities of H2O2 aqueous solutions for the whole range of H2O2 mole fractions in reasonably good agreement with experimental results. The computed diffusion coefficients for H2O2 and water molecules using the TIP4P/2005 force field with either of the H2O2 force fields are almost constant for the whole range of H2O2 mole fractions. Hydrogen bond analysis showed a steady increase in the number of hydrogen bonds with the solute concentrations in H2O2 aqueous solutions for all combinations except for the Cordeiro-TIP5P-E and Orabi-TIP5P-E systems, which showed a minimum at intermediate concentrations. The Cordeiro force field for H2O2 in combination with either of the water force fields can predict the Henry coefficients of H2O2 in water in better agreement with experimental values than the force field by Orabi & English.

Synthesis of SiO2/ZnO/Fe2O3/ZnFe2O4 from Spent Alkaline Batteries and Mining Tailings Applied as a Photocatalyst and Pseudocapacitor

In this study, a mixed oxide (SiO2/ZnO/Fe2O3/ZnFe2O4) was prepared using the anode recycled from alkaline batteries and the silt fraction of mining tailings and applied as a photocatalyst under solar irradiation and as a pseudocapacitor. The structure and morphology of the mixed oxide revealed clusters of nanometric particles with rhombic and octahedral shapes. A 23 full factorial design was performed to determine the effect of pH, hydrogen peroxide (H2O2), and photocatalyst on methylene blue (MB) decolorization. The maximum efficiency was 96%, obtained using 2.35 × 10−5 mol H2O2 and 20 mg of photocatalyst at pH 3 for 30 min under solar irradiation. This efficiency remained even after four successive decolorization cycles. Pseudocapacitive properties showed that the mixed oxide exhibited favorable characteristics for application as electrochemical pseudocapacitors due to its high capacitance (87.16 F g-1), energy density (27.24 Wh kg-1) at 524.41 W kg-1 of power density, and reversibility (93%). The studied mixed oxide has excellent potential for use in photocatalytic reactions and electrochemical devices, contributing to environmental sustainability and circular economy

Facilely prepared heterogeneous Fenton catalyst Fe(Fe0.69Al0.31)2O4@C for catalytic wet peroxide oxidation of ciprofloxacin in batch and continuous reactor: Reaction intermediates and toxicity evaluation

Herein, by using a simple co-precipitation method Al-doped magnetite spinel nanoparticle encapsulated in the carbon matrix Fe(Fe0.69Al0.31)2O4@C was synthesised and its catalytic activity was examined as a heterogeneous Fenton catalyst towards the catalytic wet peroxide oxidation (CWPO) of antibiotic pollutant 20 ppm ciprofloxacin (CIP) in batch and continuous reactors. Under the optimized conditions, 0.5 g·L-1 Fe(Fe0.69Al0.31)2O4@C in batch reactor mineralized 51 % of CIP was achieved within 180 min at 50 °C and pH 3 by utilizing 1.2 mM or 4S H2O2 (S = stoichiometry; 47 mol H2O2:1 mol CIP) which is significantly less concentration compared to other heterogeneous Fenton catalysts. Impressive long-lasting catalytic activity was demonstrated in the up-flow fixed bed reactor, for 110 h with 44 % TOC removal and less than 1 ppm Fe leaching in the effluent water. Kinetic studies on the rate of decomposition of H2O2 revealed that Fe(Fe0.69Al0.31)2O4@C effectively decomposed the H2O2 like the homogeneous Fenton catalyst. The XPS results confirmed the influence of Al on iron ions in the magnetite structure through a substantial shift in higher binding energy for Fe3+ and introduced a more electropositive character on the Fe3+(δ+) that successively expedites the kinetically slow Fe3+ reduction reaction with H2O2 to produce HOO•. The π electrons of the graphitic carbon facilitate the electron transfer between the carbon matrix and Fe(Fe0.69Al0.31)2O4 nanoparticles to enhance the CIP degradation. The acute toxicity assessment studies validated the non-toxic nature of the effluent water obtained from batch and continuous reactors. A degradation pathway was proposed based on the eleven intermediate products identified using LC-HRMS analysis.

A Bio‐Inspired Methylation Approach to Salt‐Concentrated Hydrogel Electrolytes for Long‐Life Rechargeable Batteries

AbstractHydrogel electrolytes hold great promise in developing flexible and safe batteries, but the presence of free solvent water makes battery chemistries constrained by H2 evolution and electrode dissolution. Although maximizing salt concentration is recognized as an effective strategy to reduce water activity, the protic polymer matrices in classical hydrogels are occupied with hydrogen‐bonding and barely involved in the salt dissolution, which sets limitations on realizing stable salt‐concentrated environments before polymer‐salt phase separation occurs. Inspired by the role of protein methylation in regulating intracellular phase separation, here we transform the “inert” protic polymer skeletons into aprotic ones through methylation modification to weaken the hydrogen‐bonding, which releases free hydrogen bond acceptors as Lewis base sites to participate in cation solvation and thus assist salt dissolution. An unconventionally salt‐concentrated hydrogel electrolyte reaching a salt fraction up to 44 mol % while retaining a high Na+/H2O molar ratio of 1.0 is achieved without phase separation. Almost all water molecules are confined in the solvation shell of Na+ with depressed activity and mobility, which addresses water‐induced parasitic reactions that limit the practical rechargeability of aqueous sodium‐ion batteries. The assembled Na3V2(PO4)3//NaTi2(PO4)3 cell maintains 82.8 % capacity after 580 cycles, which is the longest cycle life reported to date.

A Bio-Inspired Methylation Approach to Salt-Concentrated Hydrogel Electrolytes for Long-Life Rechargeable Batteries.

Hydrogel electrolytes hold great promise in developing flexible and safe batteries, but the presence of free solvent water makes battery chemistries constrained by H2 evolution and electrode dissolution. Although maximizing salt concentration is recognized as an effective strategy to reduce water activity, the protic polymer matrices in classical hydrogels are occupied with hydrogen-bonding and barely involved in the salt dissolution, which sets limitations on realizing stable salt-concentrated environments before polymer-salt phase separation occurs. Inspired by the role of protein methylation in regulating intracellular phase separation, here we transform the "inert" protic polymer skeletons into aprotic ones through methylation modification to weaken the hydrogen-bonding, which releases free hydrogen bond acceptors as Lewis base sites to participate in cation solvation and thus assist salt dissolution. An unconventionally salt-concentrated hydrogel electrolyte reaching a salt fraction up to 44 mol % while retaining a high Na+ /H2 O molar ratio of 1.0 is achieved without phase separation. Almost all water molecules are confined in the solvation shell of Na+ with depressed activity and mobility, which addresses water-induced parasitic reactions that limit the practical rechargeability of aqueous sodium-ion batteries. The assembled Na3 V2 (PO4 )3 //NaTi2 (PO4 )3 cell maintains 82.8 % capacity after 580 cycles, which is the longest cycle life reported to date.

Techno-economic analysis of the co-gasification of sewage sludge and petroleum coke

In this study, the co-gasification of sewage sludge and petroleum coke is assessed with equilibrium and numerical modeling. The gasification process of these binary wastes provides a potential pathway for waste management and environmental sustainability. First, the thermodynamic equilibrium approach is used to calculate the maximum cold gasification efficiency (CGE) at different mixture ratios in an attempt to narrow down and focus on the appropriate composition of the two kinds of feedstock within the entrained flow gasifier. Furthermore, a parametric study is conducted to show the gasification metrics, i.e., CGE and feedstock conversion, and the syngas composition at different gasification conditions. The equilibrium model is based on eight unknowns in the gasification product, namely, H2, CO, CO2, H2O, CH4, O2, Csolid, and the temperature, under variable O2 and H2O molar ratios. Using three elemental mass balances, four equilibrium (Csolid) constant relations, and energy balance, the mathematical model is developed. The model incorporates the solid unburnt carbon in the product species. The temperature of gasification is determined through an iterative process. Using the result of the equilibrium model, a high-fidelity reactive flow model that accounts for the reactor geometry and the devolatilization kinetics is developed. This model accounts for an extended set of reactions covering the char combustion, water and gas shifts, Boudouard and devolatilization. Finally, economic analysis is carried out to assess the conditions when such a process can be deemed to be profitable. The result of the model shows that the maximum CGE is achieved when all the solid carbon is converted into carbon monoxide with nearly all hydrogen present in the feedstock converted into hydrogen gas. The maximum conversion was attained with sewage sludge and petroleum coke ratio of 1 at 1,200°C. The mole fraction of the syngas species obtained is XH2 = 0.4227 and XCO = 0.5774 and a small fraction of XCH4 = 0.0123. Moreover, the cold gasification efficiency (CGE) measures 87.02% for the H2 and CO syngas species and reached 91.11% for the three species, including CH4. The gasification of the sewage sludge and petroleum coke at 50:50 is economically viable at temperatures higher than 950°C. A peak net gain of 0.16 $/kg of fuel blend was achieved at 1,250°C. At temperatures lower than 950°C, net losses were realized. This could be associated with less product gas yield, which is not significant enough to counteract the input costs. For instance, the net losses were −0.03 and −0.17 $/kg of feedstock at 950 and 800°C, respectively.

Mean dose rate in ultra-high dose rate electron irradiation is a significant predictor for O2 consumption and H2O2 yield

Objective. The objective of this study was to investigate the impact of mean and instantaneous dose rates on the production of reactive oxygen species (ROS) during ultra-high dose rate (UHDR) radiotherapy. The study aimed to determine whether either dose rate type plays a role in driving the FLASH effect, a phenomenon where UHDR radiotherapy reduces damage to normal tissues while maintaining tumor control. Approach. Assays of hydrogen peroxide (H2O2) production and oxygen consumption (ΔpO2) were conducted using UHDR electron irradiation. Aqueous solutions of 4% albumin were utilized as the experimental medium. The study compared the effects of varying mean dose rates and instantaneous dose rates on ROS yields. Instantaneous dose rate was varied by changing the source-to-surface distance (SSD), resulting in instantaneous dose rates ranging from 102 to 106 Gy s−1. Mean dose rate was manipulated by altering the pulse frequency of the linear accelerator (linac) and by changing the SSD, ranging from 0.14 to 1500 Gy s−1. Main results. The study found that both ΔH2O2 and ΔpO2 decreased as the mean dose rate increased. Multivariate analysis indicated that instantaneous dose rates also contributed to this effect. The variation in ΔpO2 was dependent on the initial oxygen concentration in the solution. Based on the analysis of dose rate variation, the study estimated that 7.51 moles of H2O2 were produced for every mole of O2 consumed. Significance. The results highlight the significance of mean dose rate as a predictor of ROS production during UHDR radiotherapy. As the mean dose rate increased, there was a decrease in oxygen consumption and in H2O2 production. These findings have implications for understanding the FLASH effect and its potential optimization. The study sheds light on the role of dose rate parameters and their impact on radiochemical outcomes, contributing to the advancement of UHDR radiotherapy techniques.

Glycerol-assisted co-electrolysis in solid oxide electrolyzer cell (SOEC) for green syngas production: A 2D modelling study

A 2D multi-physics model is developed to study the glycerol-assisted SOEC co-electrolysis process, with a novel in-tube reformer to improve the fuel utilization and reduce the temperature difference. After model validation, the effects of key operating parameters on the electrochemical performance and temperature distribution of the system are investigated. It is found that glycerol assistance can significantly reduce the operating voltage of the SOEC co-electrolysis system, thus saving over 55 % of electrical energy at 1073 K. Besides, increasing operating voltage, operating temperature and cathode H2O molar fraction promote the co-electrolysis process, leading to an increase in cathode H2O/CO2 conversion. Optimal values of the anode/cathode flow rates (Qan = 70–110 SCCM and Qca = 125–175 SCCM) and the anode glycerol molar fraction (Xan,GL = 0.05–0.15) are obtained to achieve both good electrochemical performance and uniform temperature distribution. Meanwhile, the proposed in-tube reformer can greatly reduce the temperature difference inside the cell, and by precisely controlling the structure and operating parameters of the system, a more uniform internal temperature distribution can be obtained, even allowing the system to be operated at homogeneous temperature conditions. This study provides a reference for the commercialization of efficient green syngas production and CO2 recycling by using renewable electricity.

The E–I Characteristic Model Based on the Composition Mole Ratio of an Arc on the Ice Surface

The E-I characteristic of an arc propagating over the ice surface is an essential input parameter when applying the ice flashover model. The numerical calculation and prediction of the E-I characteristic are essential to promote the numerical simulation of the discharge on the ice surface. Considering the energy balance of an arc propagates on the ice surface, this paper establishes an E-I characteristic model based on the mole ratio of the arc composition. The particle composition, transport, and E-I characteristics are obtained, and the model’s rationality is verified by comparing it with the existing data. Finally, the influence of the arc’s mole ratio and the arc radius on the E-I characteristics is analyzed. The results show that the E-I characteristics increase linearly with the increase of H2O molar ratio and decrease with the increase of arc radius, which has a saturation trend. The research results can provide a reference for the numerical simulation of an arc propagating over the ice surface.

Green route for biomethane and hydrogen production via integration of biogas upgrading using pressure swing adsorption and steam-methane reforming process

Biogas is a cornerstone within a clean and sustainable energy portfolio, while hydrogen production from biogas is a key enabler for methane conversion and carbon dioxide valorization for greenhouse gases emissions mitigation. In this work, pressure swing adsorption (PSA) configuration of two vessels-four adsorption beds connected in series was tested for upgrading low-grade biogas (50% CH4 and 50% CO2). To resolve CH4 spillage issue, steam-methane reforming (SMR) plant was proposed as a green route for converting CH4 and portion of CO2 in the waste stream of PSA system into hydrogen. The integrated system (PSA-SMR) was performed on two stages i.e., PSA runs were conducted experimentally in lab while SMR system was simulated using Aspen Hysys software under operating conditions from a real plant. Response surface methodology was applied into Design Expert software to optimize the effects of system pressure, CH4 concentration, and biogas/steam flowrate ratio on H2, CO2, H2O, and CO molar fractions in the product. The results revealed that four adsorption beds in serial configuration successfully recorded ultrapure CH4 of 99.9% and recovery of 84.9% along with average CO2 content of 60% in the waste stream. For SMR system, produced syngas comprised of 42.2% H2, 28.46% CO2, 13.84% N2, 8.88% H2O, and 6.66% CO with 100% conversion of the CH4 and about 52.56% conversion of the CO2. The optimum conditions that achieved the highest H2 content of 51% from SMR were system pressure below 32 bar, methane content in feed stream ≥61%, and biogas/steam ratio in the range of 0.41–0.66 to record H2.

Simultaneous hydrodynamic cavitation and glow plasma discharge for the degradation of metronidazole in drinking water

In this study, a novel hydrodynamic cavitation unit combined with a glow plasma discharge system (HC-GPD) was proposed for the degradation of pharmaceutical compounds in drinking water. Metronidazole (MNZ), a commonly used broad-spectrum antibiotic, was selected to demonstrate the potential of the proposed system. Cavitation bubbles generated by hydrodynamic cavitation (HC) can provide a pathway for charge conduction during glow plasma discharge (GPD). The synergistic effect between HC and GPD promotes the production of hydroxyl radicals, emission of UV light, and shock waves for MNZ degradation. Sonochemical dosimetry provided information on the enhanced formation of hydroxyl radicals during glow plasma discharge compared to hydrodynamic cavitation alone. Experimental results showed a MNZ degradation of 14% in 15 min for the HC alone (solution initially containing 300 × 10−6 mol L−1 MNZ). In experiments with the HC-GPD system, MNZ degradation of 90% in 15 min was detected. No significant differences were observed in MNZ degradation in acidic and alkaline solutions. MNZ degradation was also studied in the presence of inorganic anions. Experimental results showed that the system is suitable for the treatment of solutions with conductivity up to 1500 × 10−6 S cm−1. The results of sonochemical dosimetry showed the formation of oxidant species of 0.15 × 10−3 mol H2O2 L−1 in the HC system after 15 min. For the HC-GPD system, the concentration of oxidant species after 15 min reached 13 × 10−3 molH2O2L−1. Based on these results, the potential of combining HC and GPD systems for water treatment was demonstrated. The present work provided useful information on the synergistic effect between hydrodynamic cavitation and glow plasma discharge and their application for the degradation of antibiotics in drinking water.

2D-imaging of absolute OH and H2O2 profiles in a He–H2O nanosecond pulsed dielectric barrier discharge by photo-fragmentation laser-induced fluorescence

Pulsed dielectric barrier discharges (DBD) in He–H2O and He–H2O–O2 mixtures are studied in near atmospheric conditions using temporally and spatially resolved quantitative 2D imaging of the hydroxyl radical (OH) and hydrogen peroxide (H2O2). The primary goal was to detect and quantify the production of these strongly oxidative species in water-laden helium discharges in a DBD jet configuration, which is of interest for biomedical applications such as disinfection of surfaces and treatment of biological samples. Hydroxyl profiles are obtained by laser-induced fluorescence (LIF) measurements using 282 nm laser excitation. Hydrogen peroxide profiles are measured by photo-fragmentation LIF (PF-LIF), which involves photo-dissociating H2O2 into OH with a 212.8 nm laser sheet and detecting the OH fragments by LIF. The H2O2 profiles are calibrated by measuring PF-LIF profiles in a reference mixture of He seeded with a known amount of H2O2. OH profiles are calibrated by measuring OH-radical decay times and comparing these with predictions from a chemical kinetics model. Two different burst discharge modes with five and ten pulses per burst are studied, both with a burst repetition rate of 50 Hz. In both cases, dynamics of OH and H2O2 distributions in the afterglow of the discharge are investigated. Gas temperatures determined from the OH-LIF spectra indicate that gas heating due to the plasma is insignificant. The addition of 5% O2 in the He admixture decreases the OH densities and increases the H2O2 densities. The increased coupled energy in the ten-pulse discharge increases OH and H2O2 mole fractions, except for the H2O2 in the He–H2O–O2 mixture which is relatively insensitive to the additional pulses.

Correlation between Photocatalytic Properties of ZnO and Generation of Hydrogen Peroxide—Impact of Composite ZnO/TiO2 Rutile and Anatase

The generation of hydrogen peroxide on commercial and synthesized ZnO from different precursors was studied using two model molecules, formic acid (FA) and phenol (Ph), as well as phenolic intermediates, hydroquinone (HQ), benzoquinone (BQ), and catechol (CAT). The samples were characterized using X-ray Diffraction (XRD), Transmission Electronic Microscopy (TEM), RAMAN, and Electron Paramagnetic Resonance (EPR) before evaluating their photocatalytic properties. We found that the improved efficiency is accompanied by a high level of H2O2 production, fewer oxygen vacancies, and that the number of moles of H2O2 formed per number of carbon atoms removed is similar to the degradation of FA and Ph with a factor of 1. Moreover, a comparative study on the formation of H2O2 was carried out in the presence of TiO2 rutile and TiO2 anatase, with commercial ZnO. Our results exhibit the impact of the presence of TiO2 on the decomposition of hydrogen peroxide and the formation of phenolic intermediates, which are much lower than those of ZnO only, which is in agreement with the formation of hydroxyl radicals °OH and superoxide O2°− degrading significantly hydroquinone (HQ), benzoquinone (BQ), and cathecol (CAT).