Increasing Reaction Temperature Research Articles

Exploring the joint influence of SO2 and alkali metal on FeW mixed oxides catalyst for NOx elimination

The coexistence of multiple substances in the flue gas, such as alkali metal and SO2, results in the NH3-SCR catalysts suffering from serious deactivation. Therefore, we systematically studied the effects of coexisting SO2 and Na on the FeW oxides for NOx elimination. This study elucidates that the joint influence mechanism of these substances on SCR activity was regulated by reaction temperatures. When the temperature was below 300oC, the catalyst suffered a double whammy. The addition of SO2 in process of NH3-SCR resulted in a decrease in the activity of Na-poisoned FeW catalyst. It was largely due to the formation of inorganic SO42-, which not only consumed the NH3 but also blocked active sites. With the increase of reaction temperatures above 300oC, the SO2 could interact with Na2O to construct a ternary electron interaction of SO42--Na+-FeW, contributing to the improvement of alkali metal resistance. This sulfate adjusted the D-band center energy of the catalyst closer to the Fermi level, thereby boosting the adsorption energies of NH3 and NO, increasing their adsorption abilities. Furthermore, sulfate binding broke the Na-O-Fe and Na-O-W bonds, resulting in the restoration of Fe-O-W and Fe-O-Fe active sites and accumulation of Na+ species. Precise characterizations and theoretical calculations shed light on the joint mechanism of SO2 and alkali metals which provide guidance to the design SCR catalyst with excellent resistance to SO2 and alkali metal poisoning.

Antioxidant activity and cytotoxicity of greigite nanoparticles synthesized by hydrothermal technique.

The effects of 180, 210, and 230°C reaction temperatures on the structural and magnetic properties of synthesized iron sulfide nanoparticles were studied. The Rietveld refinement analysis result of the X-ray diffraction data indicated that greigite was the dominant phase in all samples. The sample was prepared at 210°C for 18h and had a greater wt% ratio of the greigite phase. The crystallite and particle sizes increased with increasing reaction temperatures. Scanning electron microscope images confirmed the presence of aggregation of synthesized rod-shaped nanoparticles. The magnetic hysteresis curves of all samples showed ferromagnetic behavior at room temperature. The magnetic saturation of three samples increases with increased reaction temperature, but the coercive force has the opposite behavior. Antioxidant activity and cytotoxicity of the sample synthesized at 210°C were investigated. This sample killed cancer cells at relatively moderate and high concentrations with high viability of normal cells, demonstrating the sample's suitability for use in killing cancer cells while avoiding normal cells.

Thermochemical conversion of guaiacol with supercritical CO2: Experimental insights

The excessive CO2 in the environment resulting from the combustion of fossil fuels has posed a significant challenge in terms of its conversion and utilization. In this work, the thermochemical conversion of guaiacol under supercritical CO2 (scCO2) was proposed, which not only enabled the consumption of CO2 but also facilitated the conversion of biomass into valuable products. It was concluded that the carbon gasification efficiency (CE) and hydrogen gasification efficiency (HE) were 37.10 % and 51.77 %, respectively, when the CO reached the maximum of 8.72 ± 0.28 mol/kg at 700 °C for 20 min. The addition of catalyst promoted the production of H2 and increased CE, the H2 yield of guaiacol gasification under different catalysts was ordered as Al2O3 > KOH > without catalyst > KCl. As the reaction temperature increased, the unreacted guaiacol and phenol decreased and were gradually converted to liquid products such as pyrene and benzo[c]phenanthrene. With the increase in reaction temperature, the more fully guaiacol was reacted, the easier it was to carbonize and form more carbon microspheres. In addition, reaction pathways for free radicals were proposed, including cleavage of free radicals, isomerization of free radicals, secondary cleavage of free radicals and recombination of free radicals. In short, degrading guaiacol using scCO2 is a feasible approach, which provides a new direction for the disposal and energy recovery of biomass in the future.

Synthesis of calcium sulfate hemihydrate whiskers from high-purity salt gypsum in a glycerol–water solution at atmospheric pressure

Calcium sulfate hemihydrate whiskers (CSHWs) were prepared from high-purity salt gypsum in a glycerol–water system. The effects of the glycerol/water ratio, reaction temperature, reaction time, and stirring speed on the crystal morphology of the CSHWs were investigated. Results showed that the average length and average length/diameter (L/D) ratio of the CSHWs first increased and then decreased as the glycerol/water ratio, reaction time, and stirring speed were increased, but they continued to gradually increase with increasing reaction temperature. The CSHWs had the highest L/D ratio and smooth surfaces—with an average length of 42.91 μm, an average diameter of 0.72 μm, and an average L/D ratio of 55—when the preparation conditions were a glycerol/water ratio of 2.0, a reaction temperature of 100 °C, a reaction time of 2.0 h, and a stirring speed of 300 rpm. This study provides a feasible idea for the treatment of salt gypsum, which achieves high value-added utilization of salt gypsum as well as the elimination of solid waste.

Insights into the hydrolysis/alcoholysis/ammonolysis mechanisms of ethylene naphthalate dimer using density functional theory (DFT) method

Hydrolysis, alcoholysis and ammonolysis are viable routes for the efficient degradation and recycling of polyethylene naphthalate (PEN) plastic waste. Various possible hydrolysis/alcoholysis/ammonolysis reaction pathways for the degradation mechanism of the ethylene naphthalate dimer were investigated using the density functional theory (DFT) B3P86/6–31++G(d,p). To determine the thermodynamic and kinetic parameters, geometric structure optimization and frequency calculation were performed on a range of intermediates, transition states, and products associated with the reaction. The calculation results show that the highest energy barrier of the main element reaction step in hydrolysis is about 169.0 kJ/mol, the lowest is about 151.0 kJ/mol for ammonolysis, and the second is about 155.0 kJ/mol for alcoholysis. The main hydrolysis products of the ethylene naphthalate dimer are 2,6-naphthalenedicarboxylic acid and ethylene glycol; the main products of alcoholysis are dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol, and the main products of ammonolysis are naphthalene-2,6-dicarboxamide and ethylene glycol. Furthermore, in the process of ethylene naphthalate dimer hydrolysis/alcoholysis/ammonolysis, the decomposition reaction in the NH3 atmosphere is better than that in methanol, and the reaction in CH3OH is better than that in the H2O molecular environment, and the increase in reaction temperature can increase its spontaneity. Our study presents the molecular mechanism of PEN hydrolysis/alcoholysis/ammonolysis and provides a reference for studying the degradation of other plastic wastes.

Improving cyclodextrin yield via retarding retrogradation of debranched starches during the preparation of cyclodextrin with cyclodextrin glycosyltransferase and pullulanase

Improving substrate utilization is crucial for industrial conversion of starch. The introduction of pullulanase in cyclodextrin (CD) production has improved substrate utilization. However, complete utilization of debranched starches has not been achieved, mainly due to the retrogradation of debranched starches and the inhibitory effect of CDs on pullulanase during the catalytic reaction. This study aimed to establish an efficient CD preparation system by regulating the substrate concentration and reaction temperature. A Bacillus thermoleovorans pullulanase (BtPul) was selected for investigation of its interaction with CDs through inhibition pattern assays, fluorescence spectroscopy, and molecular docking. Results clarified that CDs inhibited BtPul, with α-CD showing the highest inhibition, followed by β-CD and γ-CD. γ-CD inhibited BtPul through a mixed mode of competitive and noncompetitive inhibition, while the other CDs inhibited BtPul competitively. When pullulan was used as the substrate, increasing the substrate concentration weakened the inhibitory effect of CDs to some degree, while changes in reaction temperature only had a minor contribution. When BtPul and β-CGTase collaboratively converted 30% (w/v) starch substrate, an increase in reaction temperature improved the conversion rate of β-CD from 67.6% to 86.8%. Optimization of substrate concentration showed that high concentration starch substrate had an adverse effect on CDs yield due to retrogradation. The optimal yields of α-CD and β-CD produced by BtPul and α-/β-CGTases were 55.7% and 90.3%, respectively. This study provides a reliable method and reference for the efficient conversion of starch into CDs.

Reaction Mechanisms and Production of Hydrogen and Acetic Acid from Aqueous Ethanol Using a Rn-Sn/TiO2 Catalyst in a Continuous Flow Reactor

The catalytic reforming of bioethanol can produce green hydrogen (H2) and acetic acid (AcOH). In the present study, the conversion of aqueous ethanol (EtOH) over 4 wt%Ru-4 wt%Sn/TiO2 in a flow reactor was investigated at different temperatures at 0.1 MPa or at various pressures at 260 °C. The ethanol conversion was rather slow in liquid water, while the reactivity increased significantly when water was evaporated. Under gas-phase conditions at 0.1 MPa, the conversion rate increased with increasing reaction temperature, but the AcOH yield and H2 purity decreased due to by-production of CH4, CO, and CO2. The CH4 and CO generated by fragmentation of acetaldehyde (AA), an intermediate, were suppressed by increasing reaction pressure, although the formation of CH4 and CO2 generated from AcOH was pressure independent. Thus, the highest-pressure conditions in steam at a given reaction temperature are preferred for the production of pure H2. The initial step, EtOH → AA, was the rate-determining reaction, and the model experiments using AA as a substrate showed that the Cannizzaro reaction of two AA molecules to form EtOH and AcOH occurred preferentially. This oxidation system was confirmed to be effective at EtOH concentrations of up to 500 g/L in water.

Hydrogen transfer reaction in butene catalytic cracking over ZSM-5

Hydrogen transfer reaction (HTR) is the pivotal side reaction in the catalytic cracking process of low carbon olefins. The intricate reaction pathways and product diversity of HTR directly impact the selective formation of ethylene and propylene. Therefore, elucidating the key HTR in various reaction pathways and defining the hydrogen transfer index (HTI) as a criterion lay a scientific foundation for precisely regulating HTR during olefin catalytic cracking process. Herein, the influence of the acid strength of ZSM-5 zeolites on the HTR degree was analyzed in butene catalytic cracking. Results showed that isobutane was the predominant component of HTR products, mainly derived from HTR during the dimerization-cracking of pentene (butene primary cracking product). Subsequent pentene catalytic cracking experiments validated this conclusion. Thus, the HTI in butene or pentene cracking process was defined as follows: for butene cracking process, HTI = Si–C4H10/SC5H10; for pentene cracking process, HTI = Si–C4H10/SC4H8. The HTI accurately reflected the extent of HTR with respect to the acid properties of the catalysts. Moreover, the reaction network of butene catalytic cracking process was optimized, providing a comprehensive explanation for the intriguing phenomenon of decreasing butene conversion with increasing reaction temperature when the acid strength of ZSM-5 was weak. Finally, a high-performance butene catalytic cracking catalyst, De-TS-1-0.25%P, was developed, exhibiting high olefin selectivity (92.33 %) and outstanding stability (307 h) in the conversion of butene.

Investigation of an indigenous chalcopyrite ore leaching in ammonia solution: characterization, leaching and kinetics

ABSTRACT Chalcopyrite ore is one of the most abundant and pertinent oxidized copper minerals. In this research, the dissolution kinetics of chalcopyrite in an ammonia solution was examined. During leaching, the influences of leachant concentration, temperature, and particle diameter on the extent of copper ore dissolution were investigated. However, it was affirmed that the dissolution efficiency of chalcopyrite ore increased with decreasing particle fraction and increasing reaction temperature and ammonia concentration. About 68.6% copper ore dissolution was achieved with 2.0 mol/L NH3, 75 ºC reaction temperature, and 45 μm particle diameter within 120 minutes. The dissolution reaction mechanism was found to be described by diffusion-control with a calculated activation energy of 32.26 kJ/mol. In the XRD spectra of the residual product obtained at established conditions, CuFeS2 peaks were absent, indicating the leachability of the sample. Hence, the leach residue could serve as an important by-product for some local industries.

The Oxidation Performance of a Carbon Soot Catalyst Based on the Pt-Pd Synergy Effect

Pt-Pd-based noble metal catalysts are widely used in engine exhaust aftertreatment because of their better carbon soot oxidation performance. At present, the synergistic effect of Pt and Pd in CDPFs, which is the most widely used and common doping method, in catalyzing the combustion of carbon smoke has not been reported, and it is not possible to give an optimal doping ratio of Pt and Pd. This paper investigates the carbon soot oxidation performance of different Pt/Pd ratios (Pt/Pd = 1:0, 10:1, 5:1, 1:1) based on physicochemical characterization and particle combustion kinetics calculations, aiming to reveal the Pt-Pd synergistic effect and its carbon soot oxidation law. The results show that Pt-based catalysts doped with Pd can improve the catalyst dispersion, significantly increase the specific surface area, and reduce the activation energy and reaction temperature of carbon soot reactions, but excessive doping of Pd leads to the enhancement of the catalyst agglomeration effect, a decrease in the specific surface area, and an increase in the activation energy and reaction temperature of the carbon soot reaction. The specific surface area and pore capacity of the catalyst are the largest, and the activation energy of particle oxidation and the pre-exponential factor are the smallest (203.44 kJ∙mol−1 and 6.31 × 107, respectively), which are 19.29 kJ∙mol−1 and 4.95 × 108 lower than those of pure carbon soot; meanwhile, the starting and final combustion temperatures of carbon soot (T10 and T90) are the lowest at 585.8 °C and 679.4 °C, respectively, which are 22.1 °C and 20.9 °C lower than those of pure carbon soot.

Nanopore construction in SiC aerogels for continuous dual-peak electromagnetic wave absorption with full Ku-band coverage

SiC aerogels have been extensively studied for electromagnetic wave (EMW) absorption because of their tunable dielectric properties. Continuous dual-peak EMW absorption can broaden the effective absorption bandwidth (EAB); however, few SiC aerogels have been reported to exhibit this phenomenon and the mechanisms to achieve this through microstructure design remain unclear. In this study, size-tunable nanopores were constructed in SiC aerogel by a simple carbothermal reduction method, which gradually increase with increasing reaction temperature. The mechanism of the nanopore formation in SiC aerogels is also discussed in detail. The optimized SiC aerogel prepared at a reaction temperature of 1550 °C exhibited continuous dual-peak EMW absorption with a maximum EAB of 6.24 GHz (11.76–18 GHz), full Ku-band coverage, and minimum reflection loss of −32.59 dB. This continuous dual-peak EMW absorption was ascribed to the overlap of the secondary peak caused by the nanopore-induced strong dielectric resonance and the main peak caused by SiC. The results of this study will provide inspiration for the design of microstructures for continuous dual-peak absorption in EMW absorption materials.

Synthesis of TiCx/Al Composites via In Situ Reaction between AlxTi Melt and Dissolvable Solid Carbon

TiCx/Al composites were successfully prepared in this study by dissolving graphite particles in Al-Ti melt based on the principle of a solid–liquid in situ reaction. It was observed that the microstructure of the TiCx/Al composites changed with changes in the reaction temperature and graphite particle size. With an increase in reaction temperature, the TiCx particles in the TiCx/Al composites transitioned from a spider-like distribution to being evenly dispersed in the Al matrix. Additionally, the morphology of the TiCx particles changed from polygons of various sizes to quasi-spherical shapes with a uniform particle size, while the presence of Al4C3 and Al3Ti in the matrix diminished. The size variation of the graphite particles had minimal impact on the particle size and stoichiometric ratio of TiCx generated in the sample. Furthermore, an appropriate graphite particle size was found to mitigate the agglomeration and residue of graphite particles during the in situ reaction.

Heavy oil atmospheric residue: HDS performance and life test using ARDS catalysts system

The objective of this study is to evaluate the catalyst by introducing atmospheric residue of heavy crude (H-AR) that secures full comprehensive characteristics and converts into a petroleum product, namely low sulfur fuel oil (LSFO). Furthermore, to estimate the catalyst’s lifespan under hydroprocessing conditions by monitoring its deactivation rate and maintaining consistent sulfur in LSFO products through gradual increases in reaction temperature. Prior to the hydrotreating test, the heavy crude oil underwent desalting, dewatering, and atmospheric distillation to obtained atmospheric residue (H-AR, i.e., 350°C+) for use as feedstock. The pilot plant employed a catalyst system comprising both hydrodemetallization (HDM) and hydrodesulfurization (HDS) catalysts, distributed across two fixed-bed reactors. The results showed the lifespan approximately 3.0 months as a function of time-on-stream (TOS). The H-AR feed, with its high sulfur, metals, asphaltenes, and micro carbon residue (MCR) content, poses several challenges including carbon deposition at start of run (SOR). The observed deactivation rate is attributing to the feedstock’s poor quality and its impact associated deposition of coke and metals (V and Ni) deposition with TOS.

Deciphering the Pivotal Reaction Conditions for Hydrogen Production from Tar Catalytic Cracking by Perovskite

The catalytic cracking of pyrolysis gasification tar into H2 has garnered significant attention due to its exceptional conversion efficiency. In this study, the effects of pollutant concentration, residence time, weight hourly space velocity (WHSV), and reaction temperature on the hydrogen performance of LaFe0.5Ni0.5O3 perovskite were comprehensively investigated. Results revealed that moderate pollutant concentration (0.3 g/L), low-medium residence time (250 SCCM), and low WHSV (0.24 gtoluene/(gcat·h)) facilitated efficient interaction between LaFe0.5Ni0.5O3 and toluene, thus achieving high hydrogen production. An increase in reaction temperature had minimal effect on the hourly hydrogen production above 700 °C but caused a significant increase in methane production. Additionally, the effects of oxygen evolution reactions, methane reactions, and methane catalytic cracking reactions of perovskite induced by different reaction conditions on tar cracking products were discussed in detail. Compared to previous reports, the biggest advantages of this system were that the hydrogen production per gram of tar was as high as 1.002 L/g, and the highest hydrogen content in gas-phase products reached 93.5%, which can maintain for approximately 6 h. Finally, LaFe0.5Ni0.5O3 showed good thermal stability, long-term stability, and catalyst reactivation potential.

Generic heterostructure interfaces bound to Co9S8 for efficient overall water splitting supported by photothermal

The increase of reaction temperature of electrocatalysts and the construction of heterogeneous structures is regarded as an efficient method to improve the electrocatalytic water splitting activity. Here, we report an approach to enhance the local heat and active sites of the catalyst by building a heterostructure with Co9S8 to significantly improve its electrocatalytic performance. The as-fabricated Co9S8@Ce-NiCo LDH/NF electrode possesses a notable photothermal ability, as it effectively converts near-infrared (NIR) light into the local heat, owing to its significant optical absorption. Leveraging these favorable qualities, the prepared Co9S8@Ce-NiCo LDH/NF electrode showed impressive performance in both hydrogen evolution reaction (HER) (η100 = 144 mV) and oxygen evolution reaction (OER) (η100 = 229 mV) under NIR light. Compared to the absence of the NIR light, the presence of NIR irradiation leads to a 24.6 % increase in catalytic efficiency for HER and a 15.8 % increase for OER. Additionally, other dual-functional electrocatalysts like NiCo-P, NiFeMo, and NiFe(OH)x also demonstrated significantly enhanced photothermal effects and improved catalytic performance owing to the augmented photothermal conversion when combined with Co9S8. This work offers novel pathways for the development of photothermal-electrocatalytic systems that facilitate economically efficient and energy-conserving overall water splitting processes.

Production of esters with numerous applications: Kinetics of Dowex 50W catalyzed transesterification of methyl acetate with three‐ and four‐carbon structured alcohols

AbstractIn this investigation, a strongly acidic exchange resin was used for the transesterification of methyl acetate with n‐propanol, n‐butanol, and iso‐butanol. Kinetic and equilibrium experiments for the three systems were conducted using a temperature‐controlled batch reactor setup. The effects of the following operating parameters on the transesterification were explored: reaction temperature, catalyst loading, and methyl acetate‐to‐alcohol molar ratio. The conversion of the limiting reactant in the reaction mixture increased with increasing reaction temperature, catalyst loading, and varying reactant proportions from 1:1 to other ratios. It was found that excess methyl acetate would result in higher limiting reactant conversion than using excess alcohol with the same initial molar proportionality between the excess and the limiting reactants. It was found that an increase in the chain length of the alcohol and/or branching suppressed the conversion of the reactants owing to steric hindrance. To mathematically correlate the data, several kinetic models were tested, and the Eley–Rideal model was selected. Accordingly, a reaction mechanism was proposed.

Research on V2O3 preparation by stepwise catalysis solution-phase hydrogen reduction from shale V-rich solution

Solution-phase hydrogen reduction reaction (SpHR) was introduced to overcome the problems of ammonia nitrogen pollution, high energy consumption, and long production flow of traditional reduction roasting. From φ-pH diagram, the increase of reaction temperature, vanadium concentration and H2 partial pressure is beneficial to the preparation of V2O3. High purity V2O3 could not be prepared by single addition catalysis and synchronous catalysis in SpHR process, and the Ni + NiSO4 stepwise catalysis can effectively eliminate the problem of nickel wrapped in vanadium precipitates during the precipitation process. Under the optimal conditions of Ni + NiSO4 stepwise catalysis of nickel powder dosage 5 g/L, NiSO4 dosage 8 g/L, nickel powder catalytic time 90 min, NiSO4 catalytic time 30 min, the precipitate with nickel content 11.15 % was obtained, and Ni catalyst can be separated by magnetic separation with nickel recovery ratio of 99.52 %. Ni2+ in SpHR precipitates to Ni(OH)2 and then disintegrates and reduces to Ni, and Ni + NiSO4 stepwise catalysis includes two steps of pre-catalysis and secondary catalysis. After fourth cyclic experiment, the vanadium content of V2O3 product obtained was 67.46 % (i.e. 99.21 % V2O3 purity met the requirements of GB 40301–2021), the total recovery was 98.68 %, and the vanadium loss ratio was stable at 1.22 %. The process of SpHR has no ammonia nitrogen wastewater or waste gas discharge, and the price of V2O3 with purity more than 99 % on the market is about 260,000 ¥/t. The stepwise catalysis SpHR has remarkable environmental benefits and economic benefits.

Effect of reaction conditions on the agglomeration of the oxygen carrier in biomass chemical looping gasification

The oxygen carrier (OC) agglomeration is an important factor limiting the development of biomass chemical looping gasification (CLG) technology. However, the agglomeration behavior of OC is not clear under multiple perspectives of reaction conditions. In this study, we investigated the Fe-based OC agglomeration behavior during CLG from three perspectives of biomass species, reaction temperature and steam/biomass (S/B). The results showed that biomass with high ash and K content was easy to form more low melting point substances, causing a lower deformation temperature (DT) and more severe agglomeration of OC after CLG. Moreover, with the increase of reaction temperature from 700 °C to 900 °C, the DT of OC decreased by 6.8 %, while the average particle size and agglomeration degree of OC increased by 26.2 % and 209.5 %, respectively. Although high temperature was beneficial for improving reaction performance and shortening reaction time, the excessive temperature would cause severe agglomeration and inhibit CLG process. In addition, the higher the S/B was, the more severe the agglomeration became. With the increase of S/B from 0 to 1.8, the DT of OC decreased by 3.2 %, while the average particle size and agglomeration degree of OC increased by 28.2 % and 75.5 %, respectively. The excessive S/B would form more KOH and NaOH with lower melting point, exacerbating the OC agglomeration and inhibiting the gasification.

Preparation of tobacco pyrolysis liquids in subcritical/supercritical ethanol and their application in the aroma enhancement of heated cigarettes.

For the aroma enhancement research of heated cigarettes, it is worth exploring whether tobacco can be pyrolyzed into pyrolysis liquids containing a large number of volatile aroma components. In this study, tobacco pyrolysis liquids were prepared in subcritical/supercritical ethanol, and their applications in the aroma enhancement of heated cigarettes were investigated. The optimal conditions of supercritical liquefaction reactions were determined by optimizing the reaction time, liquid/solid mass ratio and temperature conditions. Moreover, the effect of supercritical liquefaction conditions on volatile aroma components in tobacco pyrolysis liquids was investigated by GC-MS. The results indicated that the reaction temperature had the most significant impact on the tobacco pyrolysis reaction, and higher reaction temperature promoted the pyrolysis conversion of tobacco, resulting in enhanced tobacco conversion and a high content of volatile components in the tobacco pyrolysis liquid. The optimal reaction conditions for the preparation of tobacco pyrolysis liquid were found to be a temperature of 220°C, a liquid/solid mass ratio = 15, and a 2-h reaction time. Meanwhile, the content of ester compounds and nicotine in the tobacco pyrolysis liquid increased significantly with the increase of reaction temperature. Sub/supercritical ethanol treatment significantly destroyed the surface structure of tobacco, and the degree of tobacco depolymerization increased when temperature rised. The analysis of aroma compounds in the smoke of heated cigarettes indicated that the tobacco pyrolysis liquid could significantly increase the release of aromatic substances and has a significant aroma-enhancing effect. This article proposed and prepared tobacco pyrolysis liquid in subcritical/supercritical ethanol and explored its potential application in the aroma enhancement of heated cigarettes, offering a new route for flavor enhancement technology for this type of product.

A novel sugarcane residue-derived bimetallic Fe/Mn-biochar composite for activation of peroxymonosulfate in advanced oxidation process removal of azo dye: Degradation behavior and mechanism

Metal-biochar composites with varying Fe/Mn ratios were synthesized for activating peroxymonosulfate (PMS) oxidative degradation of azo dye Orange G (OG) were investigated. The 1Fe2Mn-BC composite based on 1:2 molar ratio impregnation of Fe/Mn salt concentrations of efficient sugarcane harvest residue showed the best catalytic performance under aqueous pH 3–10 and had the least impacts from coexistence of inorganic anions and humic acids. The OG degradation by 1Fe2Mn-BC/PMS system optimized at catalyst:oxidant:pollutant ratio of 1:1.25:0.5 on g/L basis was found to follow pseudo-first-order kinetic and achieved 100 % degradation efficiency within 30 min. Apparent activation energy for OG degradation by 1Fe2Mn-BC/PMS was 16.91 kJ mol−1, and increasing reaction temperature from 293 to 313 K enhanced degradation rate constant by 49 %. Electron paramagnetic resonance (EPR) and radical quenching experiments revealed dominant non-radical 1O2 and radical O2− pathways in the OG oxidation removal by the 1Fe2Mn-BC/PMS system, although SO4− and OH radicals also participated. XPS spectra of 1Fe2Mn-BC before and after OG degradation indicated dominant surface composition of Fe(III) and Mn(II) valence states over other FeMn-biochar composites. The novel optimized one-step pyrolysis Fe/Mn bimetal biochar composite provides an efficient PMS activation for advanced oxidation process (AOP) treating of azo dyes in wastewater decontamination.