N2 Stream Research Articles

Effect of Doping ZnO on Activated Carbon Prepared from Waste Paper for Photocatalytic Applications

Accumulation of untreated and unrecycled paper has a negative impact on the environment. Like liquid waste handling, paper waste handling is also still being developed. It is known that activated carbon (AC) is one of the promising adsorbents that can be used to solve the environmental issue. Activated carbon can be made from organic waste, such as waste paper. The objective of this study is to investigate the operation condition of the pyrolysis process to obtain the activated carbon. The furnace temperature was set at 400°C for 1 hour under N2 stream with a flow rate of 0.5 L/min. To provide a synergistic effect in the adsorption process, ZnO was derived from ZnCl2 as a chemical activator for making active carbon. While Zn (CH3COO)2.2H2O with different concentrations of 0.01, 0.05, and 0.1 M was grown into the pores of activated carbon. The photocatalytic activity of AC/ZnO was identified in the degradation process of methylene blue as a model of organic pollutants. X-ray diffraction (XRD), scanning electron microscope (SEM), and fourier transform infrared (FTIR) were used to characterize the product. The morphology of ZnO was observed in the form of a flower-like and occupying the surface of activated carbon. The photocatalytic activity showed that the methylene blue was completely degraded.

Multistep kinetics of the thermal dehydration/decomposition of metakaolin-based geopolymer paste

This study investigated the kinetics of the multistep thermal dehydration/decomposition of the metakaolin-based geopolymer paste. The component two reaction steps were characterized by the evolution of water vapor and the simultaneous evolution of water vapor and CO2, respectively. In a stream of dry N2, the kinetics of the first and second reaction steps were characterized by the apparent activation energy (Ea) values of 92 and 166 kJ mol−1, respectively. Both reaction steps exhibited a diffusion-controlled rate behavior. In a stream of wet N2, the mass loss curves systematically shifted to higher temperatures with an increase in the water vapor pressure (p(H2O)). The first reaction step was significantly influenced by p(H2O), and the apparent Ea increased to 175 kJ mol−1 at p(H2O) = 11.4 kPa. The second reaction step was less sensitive to the atmospheric water vapor, as characterized by its Ea of ∼165 kJ mol−1, irrespective of the p(H2O).

Flame characteristics and NO emission behaviors of methane/ammonia counterflow premixed flames with opposed N2 or air stream

Behaviors of methane/ammonia counterflow premixed flames and NO emission are numerically and experimentally investigated with opposed N2 or air stream by varying strain rate (ag) and equivalence ratio (ϕ). The premixed stream is 80% methane and 20% ammonia by volume mixed with air considering the utilization of ammonia by blending hydrocarbon fuels. The opposed stream is either N2 or air considering the potential application in gas turbines having single- or two-stage combustion. The simulations are conducted by increasing ag up to flame extinction for a specified ϕ and an experiment is conducted to evaluate various kinetic mechanisms. The extinction strain rate increases monotonically with ϕ with opposed air stream (AS), while increases and then decreases with opposed nitrogen stream (NS). The extinction mechanisms are explained by adopting the concepts of the local equilibrium temperature and heat loss ratio. For lean and rich mixtures with NS and lean mixtures with AS, the extinction occurs due to comparable effects of incomplete reaction and heat loss from the flame to the downstream burnt region. While for rich mixtures with AS, the extinction is attributed mainly to incomplete reaction. The contribution of thermal NO as compared with prompt NO in NO production is weak for all cases with NS and AS. The emission index (EINO) for lean and rich mixtures with NS and for lean mixtures with AS decreases monotonically with the increase of strain rate for all ϕ. Increasing equivalence ratio at a specified ag decreases NO production for lean and rich mixtures with NS and lean mixtures with AS. While for rich mixtures with AS, the EINO increases monotonically with ag. From the reaction pathway analysis, for lean mixtures, the effect of increasing ag on the reduction of NO production is attributed by weakening NH-related reaction paths, while NH2-related reaction paths change little. When ϕ increases for a specified ag with NS, NO production is reduced by weakening NH2-related reaction paths and strengthening NH-related reaction paths. For rich mixtures with AS, increasing ag increases NO production by strengthening NH2-related reaction paths.

Heterogeneous reaction of NO2 with hematite: The effects of UV irradiation, O2 and relative humidity

Heterogeneous reactions on mineral dust surfaces are increasingly considered important in the removal of gaseous pollutants and the formation of secondary aerosols. Although the heterogeneous reaction of NO2 on the hematite surface has been investigated in many previous studies, little is known about the reaction of NO2 with hematite under ambient conditions. In this work, heterogeneous reactions of NO2 with hematite at 298 K were investigated via a coated-wall flow tube reactor and in situ diffuse reflectance Fourier transformed infrared spectroscopy (DRIFTS). The influence of UV illumination, relative humidity (RH) and O2 on the uptake coefficients and adsorption amount of NO2, as well as the nitrate formation on the hematite surface, has been analyzed comprehensively. UV irradiation shows a significant effect on the true uptake coefficient (γBET), which increases from 2.00 × 10−6 to 4.76 × 10−6 in the N2 stream and 1.32 × 10−6 to 4.07 × 10−6 in the air stream under dry conditions (∼0.3 % RH). RH (in the range of 0–67 %) exhibits an inhibitory effect on the adsorption of NO2 on the hematite surface because of the competition between NO2 and water molecules, that is, γBET and adsorption amount of NO2 decrease with an increase in RH under both the dark and light reaction conditions. Meanwhile, both the γBET and adsorption amount of NO2 on hematite decrease in the air stream compared to those in N2 conditions. In addition, the results from the DRIFTS experiments indicate that the presence of UV irradiation promotes the conversion of NO2 to nitrate and both the RH and O2 suppress the nitrate formation. From this research, the heterogeneous reactions between NO2 with mineral dust under ambient conditions will be better understood.

Amino acids profile of Two Chinese nuts (Juglans sigillata and Castanea mollissima ) in local markets of Kurdistan region/Iraq using HPLC

Aim: current study was aimed to study the amino acid contents of two Chinese nuts, walnuts (Juglans sigillata Dode.) and chestnuts (Castanea mollissima Blume.) from the local market of the Kurdistan region / Iraq. Methodology: Walnut fruits (Juglans sigillata) and chestnut fruits (Castanea mollissima) were collected from local market in the Kurdistan region / Iraq, samples were collected, dried and ground. one milgram of each sample was weighed, then dissolved in 10 ml High Performance Liquid Chromatography (HPLC) methanol, the sample was shaken and agitated in an ultrasonic bath for 10 minutes , then concentrated by evaporating the solvent with a stream of liquid N2 until it reached 1 ml, filtrated the liquid sample on deposable sep-pak cartridge filter ( supleco Co, Ltd),then 20 ml were injected on HPLC column . Results: firstly current study can identified thirteen amino acids from chestnuts but there are only eight amino acids were identified from walnuts. Secondly, there are big different between them in the percentage of amino acids where valine is appear in the highest percentage which record 69.43 %, while it recorded 6.32% in chestnut fruit , While threonine showed the highest percentage in chestnuts arrived to 54.09% compared to only 3.72% in walnuts fruits.

The physico-geometrical reaction pathway and kinetics of multistep thermal dehydration of calcium chloride dihydrate in a dry nitrogen stream.

Several inorganic hydrates exhibit reversible reactions of thermal dehydration and rehydration, which is potentially applicable to thermochemical energy storage. Detailed kinetic information on both forward and reverse reactions is essential for refining energy storage systems. In this study, factors determining the reaction pathway and kinetics of the multistep thermal dehydration of inorganic hydrates to form anhydride via intermediate hydrates were investigated as exemplified by the thermal dehydration of CaCl2·2H2O (CC-DH) in a stream of dry N2. The formation of CaCl2·H2O (CC-MH) as the intermediate hydrate is known during the thermal dehydration of CC-DH to form its anhydride (CC-AH). However, the two-step kinetic modeling based on the chemical reaction pathway considering the formation of the CC-MH intermediate failed in terms of the reaction stoichiometry and kinetic behavior of the component reaction steps. The kinetic modeling was refined by considering the physico-geometrical reaction mechanism and the self-generated reaction conditions to be a three-step reaction. The multistep reaction was explained as comprising the surface reaction of the thermal dehydration of CC-DH to CC-AH and subsequent contracting geometry-type reactions from CC-DH to CC-MH and from CC-MH to CC-AH occurring consecutively in the core of the reacting particles surrounded by the surface product layer of CC-AH. The acceleration of the linear advancement rate of the reaction interface during both contracting geometry-type reactions was revealed through multistep kinetic analysis and was described by a decrease in the water vapor pressure at the reaction interface as the previous reaction step proceeded and terminated.

Wood biochar as a point source CO2 adsorbent-impact of humidity on performance

Adsorption of carbon using biobased materials is a sustainable approach to point source carbon capture and storage, particularly if the biomass is a “waste” and the adsorbent can then be re-used in soils. In this work, biochar derived from fast pyrolysis of softwood residues (sawdust) was investigated as a CO2 adsorbent under humid conditions to determine the effect of water on biochar adsorption performance. Dry and wet adsorption experiments were run at concentrations of CO2 between 20–80 vol.% (balanced with N2) at 20 °C. Water concentrations were set by saturating the N2 stream and resulted in 0.5–1.8 vol.% (relative humidity of 20%–80%). For the dry gas experiments, the adsorption capacities doubled (0.83–1.98 mmol/g) as the CO2 concentration increased from 20% to 80%. The capacity did not change between wet and dry experiments for 20, 40, and 60 vol.% CO2; however, at 80 vol.% CO2, the adsorption capacity increased by 38% for the “wet” gas from the dry gas. This is potentially due to carbonates formed due to CO2 dissolution/reaction in water. The adsorption time was not impacted by the range of water concentrations studied. The Avrami kinetic model best represented the rate of adsorption in both dry and wet conditions. The fact that neither the biochar adsorption capacity nor its adsorption rate was negatively impacted by water shows that biochar can be a promising option for stack gases, which contain water vapor. However, more experiments at higher temperatures are required.

Solid Oxide Electrochemical Cells for Nitrogen and Oxygen Production

Nitrogen and oxygen are both very important commodities with a wide variety of applications in industries, such as chemical, food and metallurgical plants as well as in the medical sector. Nowadays most of the nitrogen and oxygen are produced via air separation technologies such as cryogenic distillation (ASU) or pressure swing adsorption (PSA). Both ASU and PSA offer economical and mature ways for nitrogen and oxygen production at large (>100 ton/day) or medium scales (20-100 tons/day). If one can develop a technology for providing these gases in an energy efficient and cost effective way also at small scale, preferably driven by electricity only, this would enable new applications of the gases. Such a technology would match characteristics of the future green electricity system relying on small scale (few MWs) power generation and fluctuating production..In this work we present an efficient electrochemical process for N2 and O2 production based on a solid oxide electrochemical cell technology by oxygen extraction from air. Cells with a 53 × 53 mm2 size were produced by a conventional tape casting method. They consist of a ca.10 μm CGO (Ce0.9Gd0.1O2-δ) electrolyte sandwiched between composite electrodes made from either LSCF (La0.6Sr0.4Co0.2Fe0.8O3-δ) - CGO, or LSF (La0.6Sr0.4FeO3-δ) - CGO. To boost performance at low temperature, the electrodes were infiltrated with Pr-oxide. The electrochemical performance with the different supports were characterized by obtaining current-voltage (iV) characteristics at different temperatures as well as through electrochemical impedance spectroscopy(EIS) with or without infiltration. For characterization, air was used as feed stock to the cathode compartment and air, or oxygen was used as sweep gas to the anode compartment. A voltage below 200 mV is needed to drive a current of 1 A/cm2 through the cell, which can provide a purity of 90% of N2 out at an operation temperature of 650 °C (see Figure 1a). The cells were demonstrated to operate for producing a 98% pure N2 stream without degradation over a 1500 h period (see Figure 1b).Further analysis show that the specific power consumption calculated based on the power input and outlet gas flow rate for 90% N2 production is ca. 0.1 kWh/m3 and the specific power consumption for 96% and 98% N2 production is 0.21 and 0.31 kWh/m3, respectively. A 3-fold increase in required power is observed when going from a N2 purity from 90% to 98%.Detailed electrochemical analysis and the electrochemical performance comparison between LSCF and LSF based mixed ionic electronic conductor (MIEC) electrodes will be presented. Factors limiting cell performance will as well as analysis of optimal point of operation in terms of energy consumption and reliability will also be discussed. Acknowledgment This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 862482. Figure 1

Solid Oxide Electrochemical Cells for Nitrogen and Oxygen Production

This work presents an efficient electrochemical process for N2 and O2 production based on a solid oxide electrochemical cell technology by oxygen extraction from air. Cells with a 53×53 mm2 size consist of ca.10 μm CGO electrolyte sandwiched between composite electrodes made from either LSCF-CGO, or LSF-CGO were produced by a conventional tape casting method. To boost performance at low temperature, the electrodes were infiltrated with Pr-oxide. The electrochemical performance of the cells were characterized by iV and EIS at different temperatures with air used as feed stock to the cathode compartment and air, or oxygen used as sweep gas to the anode compartment. A voltage below 200mV is achieved to drive a current of 1A/cm2 through the cell, which can provide a purity of 90% of N2 at 650 °C. The cells were demonstrated to operate for producing a >98% pure N2 stream without degradation over a 1500h period at cell voltages below 255mV.

Electrochemical Cells for Novel Routes to Ammonia

Ammonia is an extremely important chemical compound. Annual production exceeds 180 million tons of which ~80% is used for fertilizer production. The conventional production route is CO2 intensive and almost 2% of global anthropogenic CO2 emissions stems from ammonia synthesis. This will have to change over the coming decades to ensure the politically targeted emission reductions.The synthesis gas a mixture of N2 and H2 will have to be produced in a green and sustainable manner eventually only relying on green power and sustainable synthesis routes as discussed in [1]. High temperature electrochemical cells can play a role in this, not only for providing a green stream of hydrogen, but also in realizing the required N2 as discussed in [2]. Here, a special mode of operating an SOEC was proposed including feeding some air together with the steam to the SOEC cathode to produce directly a N2/H2 mixture suitable for down-stream ammonia synthesis. This can be done with excellent efficiency [2].Here, we shall present a different and in several aspects advantageous route for providing N2 for green ammonia synthesis. It is suggested to produce the N2 by electrochemical pumping the oxygen out of an air stream. The overall energy efficiency of the concept will be discussed in detail. However, the motivation to pursue this route relies on that it would be applicable on “small” scale. Considering the scale of renewable electricity sources it would be advantageous if also ammonia synthesis could be scaled down to match the small scale and distributed nature of renewable electricity generation. Here, a technology that scales just like the electrochemical routes to be applied for the Hydrogen production would be advantageous. Whereas cryogenic distillation is an energy efficient route to provide N2 it is a technology, that would not scale down well.A solid oxide cell for electrochemical production of N2 by oxygen extraction from air was developed. 5*5 cm pieces were prepared and characterized both with respect to electrochemical performance and long term durability as tracked over 2000 hr. The cells are based on a ~10 micron CGO (Ce0.9Gd0.1O2) electrolyte sandwiched between composite supports (electrodes) made in either LSCF/CGO, or LSF/CGO. (LSCF=La0.6Sr0.4Co0.2Fe0.8O3- δ , LSF= La0.6Sr0.4FeO3- δ). To boost performance at low temperature the electrodes were infiltrated with Pr-oxide [3]. The performance with the different supports is compared at a range of temperatures and current densities with and without infiltration. Both materials were found to perform well and enable current densities ~0.8 A/cm2 at ~ 150 mV polarization, when tested at 700 oC. A 90% pure N2 stream can be produced with at a cell voltage below 150mV at temperatures from 700-800 ºC. As illustrated in Fig. 1, a purer N2 stream with 96% N2 could be produced at a cell voltage below 200 mV. Also a 98% pure N2 stream was demonstrated. Moreover, the cells were demonstrated to operate without degradation over a 2000 hr. period.The results are quite promising in terms of the excellent durability demonstrated and in terms of absolute energy consumption. For comparison with literature, the energy consumption is related to the removed oxygen rather than the produced N2. At 150 mV the energy consumption is ca. 0.7 kWh/m3 of oxygen extracted. This compares well with performance reported by Wang et al. [4] describing a similar concept. The energy consumption is ca. twice what it takes to produce the oxygen via cryogenic distillation. Here, it should be noted, however, that all the produced heat (0.7 kWh/m3) can be directly utilized in synthesizing the H2 needed for the ammonia due to the endothermic nature of steam splitting. Hence, the energy invested in producing the N2 is not really wasted in this case, as also discussed in [2].The results of detailed electrochemical testing will be presented and the factors limiting cell performance will be discussed. Finally, an analysis of what dictates the optimal point of operation in terms of energy consumption and component volume and reliability is presented. Acknowledgment The work was supported by the EU commission via project; ARENHA, H2020 GRANT AGREEMENT: 862482. References Campion, N., Nami, H., Swisher, P. R., Hendriksen, P. V., & Münster, M. (2023). Renewable and Sustainable Energy Reviews, 173, 113057. 2022.John Bøgild Hansen and Peter Vang Hendriksen 2019 ECS Trans. 91 2455.Hendriksen, P. V., Khoshkalam, M., Tong, X., Tripkovic, D., Faghihi-Sani, M. A., & Chen, M. 2019 ECS Transactions, 91, 1413-1424.Mei Wang, Kamil Maciej Nowicki, and John Thomas Sirr Irvine, Journal of The Electrochemical Society, 2022, 169, 064509 Figure 1

Ultrasound assisted membrane-assisted solvent extraction for the simultaneous assessment of some drugs involved in drug-facilitated sexual assaults by liquid chromatography-tandem mass spectrometry

A simple and highly efficient ultrasound assisted membrane-assisted solvent extraction (MASE) pre-treatment method for urine has been developed and validated for the simultaneous determination of twenty-two drugs involved in drug-facilitated sexual assaults (DFSAs) by liquid chromatography-tandem mass spectrometry. MASE was performed with 4.0 mL of urine (pH adjusted at 12), 400 μL of hexane as an organic solvent inside the polypropylene membrane, and ultrasonication (45 kHz, 120 W) for 10 min. A pre-concentration factor of 40 was achieved after evaporation (N2 stream) and re-dissolution in 100 µL of methanol. Analytes were separated using a Zorbax Eclipse Plus C18 column under gradient elution with aqueous 10 mM NH4HCO3 (pH 8.0) and methanol as mobile phases. Matrix-matched calibrations allowed the assessment of DFSA drugs of quite different octanol–water partition coefficients (Ko/w), from 1.32 101 for pregabalin to 2.45 105 for clomipramine (Log P values from 1.12 (pregabalin) to 5.39 (clomipramine)). The limit of detection (LOD) was between 0.0075 to 0.37 µg L−1, with analytical recoveries ranging from 73 to 103%, and relative standard deviations (RSDs) within the 2–20% range. The applicability of the method was demonstrated after analysing urine samples under forensic investigation.

A new application of the switchable hydrophilicity solvent-based homogenous liquid–liquid microextraction to analyze synthetic cannabinoids in plasma by LC-MS/MS

Synthetic cannabinoids are still a growing trend among drug users and consist of a group of hundreds of highly potent compounds. To investigate the use of such substances, sample preparation of biological matrices is a crucial step prior to instrumental analysis. Although different efficient extraction techniques have been proposed for that aim, they usually do not fit eco-friendly guidelines that have been gaining popularity in recent years, such as Green Analytical Toxicology. This work uses describes for the first time the use of switchable hydrophilicity solvent-based homogenous liquid–liquid microextraction (SHS-HLLME) for synthetic cannabinoids. This is a green technique that replaces highly toxic organic reagents for switchable hydrophilicity solvents (SHS), substances that can be either water-miscible or immiscible depending on their protonation. Thus, by simply adjusting the pH of the system, these SHS can be used as extraction solvents. A full optimization study including type of SHS, volume of protonated SHS, volume of NaOH, salting-out effect, and extraction time was performed. The optimized procedure consisted of precipitating the proteins of 300 µL of plasma with 300 µL of acetonitrile followed by centrifugation; evaporation of the organic solvent under N2 stream; addition of 500 µL of the protonated DPA, DPA-HCl (6 M) (1:1, v/v); addition of 500 µL of NaOH (10 M); and finally centrifugation and evaporation. Validation results showed determination coefficients ≥ 0.99 for the 0.1–10 ng/mL linear range; 0.01–0.08 ng/mL as limit of detection; 0.1 ng/mL as limit of quantitation; accuracy and imprecision were within acceptable ranges; matrix effect, recovery, and process efficiency ranged from −55.6 to 185.9%, 36–56.7%, and 18.5–148.4%, respectively. The SHS-HLLME herein described was fully optimized providing satisfactory recoveries of 31 synthetic cannabinoids at low concentrations requiring only 300 µL of plasma. In addition, the validation results showed that the technique is a reliable eco-friendly alternative for clinical and toxicological analysis.

Performance study of CrN coatings prepared by DC magnetron sputtering

Cutting edge declaration strategies and the progression of advanced troublesome coating materials are fundamental for the making of high-quality mechanical components. The point of this work is to induce prepared CrN coatings by magnetron sputtering at unmistakable nitrogen stream rates and to look at the effect of moving nitrogen stream rates on the composition, film thickness and mechanical properties of the gotten chromium nitride coatings. The outcomes appear that the nitrogen stream rate impacts the sputtering rate of the coating, i.e. the affirmation rate diminishes as the degree of nitrogen interior the plasma increments. In expansion, as the nitrogen stream rate increments, the grain gage of the coating diminishes, and the hardness modulus of the coating increments. Flexibility data illustrate that extending the N2 stream rate increases the wear resistance and flexibility of the coating.

Fabrication of N-doping activated carbons from fish waste and sawdust for Acid Yellow 36 dye removal from an aquatic environment

Acid Yellow 36 (AY36) dye is a synthetic azo dye that is excessively used in various industries, causing hazardous environmental effects. The main target of this study is the preparation of self-N-doped porous activated carbon (NDAC) and the investigation in eliminating the AY36 dye from the water solution. The NDAC was prepared by mixing fish waste (60% protein content) which was considered a self-nitrogen dopant. A combination of Fish waste, sawdust, zinc chloride and urea with a mass ratio (5:5:5:1) was submitted to hydrothermal process at 180 °C for 5 h followed by pyrolysis for 1 h under N2 stream at 600, 700, and 800 °C. Fabricated NDAC was qualified as an adsorbent for recovering AY36 dye from water using batch trials. The fabricated NDAC samples were characterized by FTIR, TGA, DTA, BET, BJH, MP, t-plot, SEM, EDX, and XRD methods. The results showed the successful formation of NDAC with nitrogen mass percentage content (4.21, 8.13 and 9.85%). The NDAC prepared at 800 °C had the largest nitrogen content (9.85%) and was labeled as NDAC800. This later had 727.34 m2/g, 167.11 cm3/g, and 1.97 nm for specific surface area, the monolayer volume and the mean pores diameter respectively. By being the more efficient adsorbent, NDAC800 was chosen to test AY36 dye removal. Therefore, it is selected to investigate the removal of AY36 dye from aqueous solution by varying important parameters such as solution pH, initial dye concentration, adsorbent dosage and contact time. The removal of AY36 dye by NDAC800 was pH-dependent, with the optimum pH value 1.5 giving 85.86% removal efficiency and 232.56 mg/g maximum adsorption capacity (Qm). The kinetic data exhibited the best fit model with the pseudo-second-order (PSOM), while the equilibrium data fit well with the Langmuir (LIM) and Temkin (TIM). The mechanism of AY36 dye adsorption may be ascribed to the electrostatic contact between the dye and the available charged sites on NDAC800 surface. The prepared NDAC800 may be considered as an efficient, available, and eco-friendly adsorbent for AY36 dye adsorption from simulated water.

Thermogravimetric approach to efflorescence of sodium carbonate decahydrate

The efflorescence of sodium carbonate decahydrate (SC-DH), characterized by the solid-state thermal dehydration to form its monohydrate (SC-MH), occurs below its melting point positioned slightly above room temperature and at a lower atmospheric water vapor pressure (p(H2O)). Applying a thermogravimetry (TG) that covers temperatures lower than room temperature enabled us to systematically trace the efflorescence of SC-DH under various heating programs in a dry N2 stream, using which the kinetics of the efflorescence was formally described by the basic kinetic equation. Meanwhile, when the sample temperature reached the melting point of SC-DH midway through the efflorescence process, the thermal dehydration switched from solid-state mode to liquid-state one and exhibited a complex multistep mass loss behavior to form SC-MH. The multistep mass loss behavior and its changes with the reaction conditions were overviewed using a humidity-controlled TG at various atmospheric p(H2O).

Nickel/Biochar from Palm Leaves Waste as Selective Catalyst for Producing Green Diesel by Hydrodeoxygenation of Vegetable Oil

The objective of this research was to prepare low-cost catalyst for green diesel conversion from vegetable oil. The catalyst of nickel-dispersed biochar (Ni/BC) was prepared by direct pyrolysis of nickel precursor with palm leaves waste under N2 stream at 500 °C. The obtained catalyst was examined by using x-ray diffraction, scanning electron microscope-energy dispersive x-ray, transmission electron microscopy, gas sorption analysis, FTIR and surface acidity examination. The catalytic activity testing was performed on rice bran oil hydrodeoxygenation at varied temperature and time of reaction. Based on analyses, the results showed the successful preparation of Ni/BC with the characteristic of single nickel nanoparticles decorated on surface. The increasing specific surface area of material was conclusively remarked the surface area enhancement by nickel dispersion along with the increased surface acidity, suggesting that the material can be applied for acid catalysis applications. The Ni/BC exhibited excellent catalytic conversion of rice bran oil with the high selectivity toward diesel fraction with 85.3% yield and 92.6% selectivity. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Liquid chromatography and differential mobility spectrometry—data-independent mass spectrometry for comprehensive multidimensional separations in metabolomics

The benefits of combining drift time ion mobility (DTIMS) with liquid chromatography–high-resolution mass spectrometry (HRMS) have been reported for metabolomics but the use of differential time mobility spectrometry (DMS) is less obvious due to the need for rapid scanning of the DMS cell. Drift DTIMS provides additional precursor ion selectivity and collisional cross-section information but the separation resolution between analytes remains cell- and component-dependent. With DMS, the addition of 2-propanol modifier can improve the selectivity but on cost of analyte MS response. In the present work, we investigate the liquid chromatography–mass spectrometry (LC–MS) analysis of a mix of 50 analytes, representative for urine and plasma metabolites, using scanning DMS with the single modifiers cyclohexane (Ch), toluene (Tol), acetonitrile (ACN), ethanol (EtOH), and 2-propanol (IPA), and a binary modifier mixture (cyclohexane/2-propanol) with emphasis on selectivity and signal sensitivity. 1.5% IPA in the N2 stream was found to suppress the signal of 50% of the analytes which could be partially recovered with the use of IPA to 0.05% as a Ch/IPA mixture. The potential to use the separation voltage/compensation voltage/modifier (SV/CoV/Mod) feature as an additional analyte identifier for qualitative analysis is also presented and applied to a data-independent LCxDMS-SWATH-MS workflow for the analysis of endogenous metabolites and drugs of abuse in human urine samples from traffic control.Graphical

Thermal dehydration of D-glucose monohydrate in solid and liquid states.

The physico-geometrical reaction pathway and kinetics of the thermal dehydration of D-glucose monohydrate (DG-MH) dramatically alter by the melting of the reactant midway through the reaction. By controlling the reaction conditions, the thermal dehydration of DG-MH was systematically traced by thermoanalytical techniques in three different reaction modes: (1) solid-state reaction, (2) switching from a solid- to liquid-state reaction, and (3) liquid-state reaction. Solid-state thermal dehydration occurred under isothermal conditions and linear nonisothermal conditions at a small heating rate (β ≤ 1 K min-1) in a stream of dry N2. The kinetic behavior comprised the presence of an induction period and a sigmoidal mass loss process characterized by a derivative mass loss curve with a symmetrical shape under isothermal conditions, resembling the autocatalytic reaction in homogeneous kinetic processes. When DG-MH was heated at a larger β (≥2 K min-1), the melting of DG-MH occurred midway through the thermal dehydration process, by which a core-shell structure of molten DG-MH and surface product layer of crystalline anhydride was produced. Subsequently, thermal dehydration proceeded as a complex multistep process. Furthermore, the thermal dehydration initiated at approximately the melting point of DG-MH upon the application of a certain water vapor pressure to the reaction atmosphere, and proceeded in the liquid-state, exhibiting a smooth mass loss process to form crystalline anhydride. The reaction pathway and kinetics of the thermal dehydration of DG-MH and the corresponding changes with the sample and reaction conditions are discussed on the basis of the detailed kinetic analysis.

Efflorescence kinetics of sodium carbonate decahydrate: a universal description as a function of temperature, degree of reaction, and water vapor pressure.

The efflorescence of sodium carbonate decahydrate (SC-DH) required to form its monohydrate (SC-MH) was systematically studied under isothermal and linear nonisothermal conditions at different atmospheric water vapor pressures (p(H2O)) using a humidity-controlled thermogravimetry instrument equipped with a cooling circulator. The universal kinetic description at various temperatures (T) and p(H2O) values was evaluated using the extended kinetic equation with an accommodation function (AF) comprising p(H2O) and the equilibrium pressure of the reaction (Peq(T)). By optimizing two exponents in the AF, all kinetic data were universally described in terms of the isoconversional kinetic relationship examined at individual degrees of reaction (α). This enabled the examination of the isothermal kinetic relationship and the parameterization of the contribution of the self-generated water vapor, allowing the incorporation of kinetic data recorded in a stream of dry N2 into the universal kinetic description as a function of T, α, and p(H2O). The results indicated that the reaction is physico-geometrically controlled by the surface reaction at the hemispherical top surface of SC-DH particles and subsequent advancement of the reaction interface toward the center and bottom of these particles, where the interfacial process is regulated by an elementary step of the consumption of H2O vacancies to form the SC-MH building unit. The apparent activation energy (Ea) of ∼178 kJ mol-1 was determined using the extended kinetic approach considering the effect of p(H2O) correlated with the intrinsic Ea of the Arrhenius-type temperature dependence (∼63 kJ mol-1) by subtracting the contribution of the temperature dependence of Peq(T) in the AF.

One-step nitrogen defect engineering of polymeric carbon nitride for visible light-driven photocatalytic O2 reduction to H2O2

Polymeric carbon nitride (PCN) is an important metal-free photocatalyst for visible light-driven hydrogen peroxide (H2O2) production from O2 reduction. Herein, we synthesized the DPCN catalysts possessing nitrogen defects by one-step thermal polymerization of urea in N2 stream. As compared to the PCN conventionally synthesized in static air, X-ray photoelectrons spectroscopy (XPS) characterization disclosed that there are more pyridinic N defects in the DPCN catalysts, which is attributed to the removal of a proportion of NH3 released from urea pyrolysis by flowing N2. UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Mott–Schottky, steady-state and time-resolved photoluminescence (PL), and electrochemical impedance spectroscopy (EIS) characterizations revealed that the introduction of the nitrogen defects narrows down the band gap, improves the density of the photoexcited charge carriers, prolongs the lifetime of the charge carriers, and enhances the charge transfer efficiency. In visible light-driven photocatalytic O2 reduction to H2O2, the optimal DPCN catalyst afforded an activity of 4.35 times that of the PCN catalyst and a H2O2 concentration of 2.83 mmol L–1 after 10 h of visible light irradiation. This one-step thermal polymerization approach is valid when replacing N2 stream with Ar and He streams.