Volatile Reaction Research Articles

Multi-frequency power ultrasound (MFPU) pretreatment of crayfish (Procambarus clarkii): Effect on the enzymatic hydrolysis process and subsequent Maillard reaction

Crayfish, as a new consumer trend, has become one of the most popular freshwater aquatic foods in China, and its processed product output has been increasing year by year. In this study, the effect of multi-frequency power ultrasound (MFPU) pretreatment in various working modes including mono-, dual- and tri-frequency on the enzymatic hydrolysis and Maillard reaction of crayfish was investigated. Additionally, the underlying mechanism was also explored. Results showed that the degree of hydrolysis (DH) of crayfish was 23.89 %, while it increased to 40.78 % after MFPU pretreatment at 20/40 kHz dual-frequency, indicating that MFPU pretreatment significantly (p < 0.05) enhanced the enzymatic hydrolysis of crayfish. The crayfish protein after MFPU pretreatment exhibited a decrease in α-helix and increase in β-fold content, and the occurrence in the unfolding of the protein structure and alteration of tertiary structure. According to scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses, the MFPU pretreatment resulted in the fragmentation of crayfish protein. During the analyses of subsequent Maillard reaction, the composition and quantity of volatiles detected by the electronic nose and GC–MS indicated that MFPU pretreatment enhanced flavor of the Maillard reaction products. In conclusion, MFPU pretreatment is a promising technology for improving the degree of hydrolysis of crayfish protein and enhancing the flavor of Maillard reaction products.

Syntheses of 2,4‐Substituted Quinazolines via One‐Pot Three‐Component Reactions Based on Manganese Dioxide/tert‐Butyl Hydrogen Peroxide Co‐Oxidation Using Alcohols

ABSTRACTQuinazolines and their derivatives occur in various natural products and pharmaceuticals, and thus, various methods of synthesizing quinazolines have been explored. They have traditionally been synthesized via two‐component reactions, but these strategies often suffer from the unavailability of the starting materials and limited substrate scopes. To overcome these problems, three‐component reactions using additional N sources were developed. Aldehydes were initially used in these reactions, but alcohols are greener and less toxic than aldehydes. However, the previously reported methods involving the use of alcohols require the utilization of transition metal catalysts, ultrahigh temperatures, and extended durations. Thus, an efficient, practical method of synthesizing quinazolines using alcohol is desirable. A facile one‐pot three‐component method of synthesizing quinazolines utilizing alcohols, 2‐aminobenzoketones, and ammonium acetate is reported for the first time, using active MnO2 and tert‐butyl hydrogen peroxide (TBHP) as synergistic oxidants. MnO2 and TBHP play dual roles: First, they oxidize the alcohol to the aldehyde and then facilitate the transformation of the intermediate into the product. During alcohol oxidation, the synergistic effect of MnO2 and TBHP is particularly evident. The aldehydes generated in situ via alcohol oxidation undergo immediate subsequent reactions, thereby minimizing their volatilization and side reactions, such as oxidation and polymerization.

Sensorial flavor characteristics and volatile Maillard reaction products of Tenebrio molitor mealworm based-reaction flavors with beef broth-like flavor

Sensorial flavor characteristics and volatile Maillard reaction products of Tenebrio molitor mealworm based-reaction flavors with beef broth-like flavor

News Diffusion in Social Networks and Stock Market Reactions

Abstract We study how the social transmission of public news influences investors’ beliefs and the securities markets. Using data on social networks, we find that earnings announcements from firms in higher-centrality counties generate a stronger immediate price, volatility, and trading volume reactions. Post-announcement, such firms experience weaker price drift and faster volatility decay but higher and more persistent volume. These findings suggest greater social connectedness facilitates the timely incorporation of news into prices, as well as opinion divergence and excessive trading. We propose the social churning hypothesis, which is confirmed using granular data from StockTwits messages and household trading records.

Catalytic flash pyrolysis for recovery of gasoline-range hydrocarbons from electric cable residue using a low-cost natural catalyst: An analytical Py–GC/MS study

This investigation’s novelty and objective reside in exploring catalytic flash pyrolysis of cross-linked polyethylene (XLPE) plastic residue in the presence of kaolin, with the perspective of achieving sustainable production of gasoline-range hydrocarbons. Through proximate analysis, thermogravimetric analysis, and heating value determination, this study also assessed the energy-related characteristics of cross-linked polyethylene plastic residue, revealing its potential as an energy source (44.58 MJ kg−1) and suitable raw material for pyrolysis due to its low ash content and high volatile matter content. To understand the performance as a low-cost catalyst in the flash pyrolysis of cross-linked polyethylene plastic residue, natural kaolin was subjected to characterization through thermogravimetric analysis, X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). Cross-linked polyethylene plastic residue was subjected to thermal and catalytic pyrolysis in an analytical microreactor coupled to gas chromatography-mass spectrometry (Py–GC/MS system), operating at 500 °C, to characterize the distribution and composition of volatile reaction products. The application of kaolin as a catalyst resulted in a decline of the relative concentration of hydrocarbons in the diesel range (C8-C24) from approximately 87 % to 28 %, and a reduction in lubricating oils (C14-C50) from about 70 % to 13 %, while concomitantly increasing the relative concentration of lighter hydrocarbons in the gasoline range (C8-C12) from around 28 % to 87 %. Therefore, catalytic flash pyrolysis offers the potential for converting this plastic waste into a new and abundant chemical source of gasoline-range hydrocarbons. This process can be deemed viable and sustainable for managing and valorizing cross-linked polyethylene plastic residue.

Research on the Explosion Reaction Mechanism of Volatile Gases from Coal Dust Pyrolysis

ABSTRACT It is imperative to have an in-depth understanding of the coal dust explosion reaction mechanism to control and prevent coal explosions in the coal mining industry and promote the safe and efficient utilization of coal resources. The volatile gases are the primary components involved in coal dust explosion reactions. Therefore, studying the explosion reaction mechanism of volatile gases in coal dust is of great significance for revealing the process of coal dust explosion. This study conducted a thermogravimetric mass spectrometry (TG-MS) experiment to analyze the mass loss characteristics and volatile gas components during coal dust pyrolysis. Experimental results showed that the pyrolysis process of coal dust is mainly divided into three stages. The main components of volatile gases escaping from coal dust pyrolysis are CO, CH4, CO2, and H2O. Then, the Chemkin-Pro numerical simulation method was also introduced to analyze the mixture explosion reaction process of coal dust pyrolysis volatile gas. The sensitivity analysis and the rates of production analysis (ROP) of reactants, products, and intermediate products during the volatile gas explosion reaction were conducted. Furthermore, 14 components and 27 key elementary reactions involved in the reaction process were simplified and extracted. A simplified reaction pathway for the mixture explosion of coal dust pyrolysis volatile gas was constructed. This study introduces a novel approach to investigate the mechanism of homogeneous combustion of volatile gases in coal dust explosion reactions.

Reactive particle-laden flow in industrial-scale supercritical water gasification reactor: Modeling and study on flow patterns

Coal gasification in supercritical water (SCW) is a highly complicated reactive particle-laden flow process, which couples multiphase flow hydrodynamics, conjugate heat transfers, and complex chemical reactions. A quantitative understanding is the key issue for reactor design and optimization. In this study, the Eulerian-Eulerian model is used to describe the particles-SCW flow in a novel industrial-scale thermally integrated supercritical water gasification (TISCWG) reactor with conjugate heat transfer boundary conditions and porous media model. The sophisticated chemical reactions are using a species transport model with a seven-step lumped kinetics. Four zones of the TISCWG reactor and four typical flow patterns in the gasification chamber are firstly revealed as 1) the bottom accumulation region with the nonhomogeneous solids distribution and back-mixing of particles, 2) the upper developed fluidization region with the SCW and coal particles moving in a plug-flow regime in the center and a downward annular gravity-driven flow near the wall, 3) the jet-affected region strongly affected by the vortexes near the nozzle and presented as a trans-critical jet regime and 4) the dilute region where dilute solids slow down and fall back into the gasification zone. Flow in the gasification chamber is strongly affected by the heat transfer with the preheat zone, as reflected by an annular gravity-driven flow film flowing downwards near the gasification wall. A funnel-shaped structure promotes a more uniform distribution of solids in the accumulation region rather than a cylindrical structure. The effect of flow patterns on coal gasification processes is also studied. Volatile pyrohydrolysis reactions depend on the time-varying solids distribution and the gaseous products at the system outlet with a typical H2 mole fraction of 61.42% and CO2 of 34.98%.

Capturing the situated, dynamic nature of EMI-lecture listening comprehension in real time

Abstract English-medium instruction (EMI) potentially offers pedagogical efficiency by simultaneously providing access to academic content and English affordances. EMI’s efficacy and effectiveness, however, remain unproven with questions concerning students’ language proficiency unresolved. As listening to lectures holds a central role in tertiary education and the development of language skills is founded on second-language listening ability, key concerns for stakeholders are knowing how much of an EMI lecture students can understand and what factors impact their lecture listening comprehension. Current methodologies used to capture listening comprehension data, such as tests, surveys, summaries, and transcript markings do not capture the idiosyncratic, volatile, and multifaceted reactions to aural text phenomena that learners encounter during a lecture. This study, therefore, uses an innovative foot switch mechanism to capture comprehension data in real time as students participated in an EMI lecture. These data were then used to guide a stimulated recall. The data showed learners failing to comprehend extensive sections of the lecture while deeper analysis identified sections of the lecture where issues concerning prior taught knowledge, top-down schema building, lexical, and bottom-up identification of sounds coincided for multiple learners. Extrapolating from these points of convergence, pedagogical recommendations are provided.

On-line cure monitoring of phenol formaldehyde resin using embedded fiber Bragg grating sensor

On-line cure monitoring techniques have shown advantages for identifying the stages of curing and can lead to smart curing process of resin system and its composites. In this study, an on-line measuring technique with fiber Bragg grating (FBG) sensors was used to gain clear understanding of the curing stages of phenolic resin, as well as to determine its chemical shrinkage level. The FBG sensors were embedded in phenolic resin and worked under temperature raising and isothermal conditions. Through the interface between FBG sensor and resin, curing shrinkage strain was transferred to the grating, changing the central wavelength of FBG and producing strain. The feasibility of FBG sensors for monitoring chemical shrinkage during curing was verified by employing epoxy and benzoxazine resins that exhibits low chemical shrinkage. For cure monitoring of phenolic resin, the results show that the strain signal can be corresponded to various responses, such as solvent volatilization, hydroxylation and dehydration condensation reactions during temperature raising curing process. Through these strain characteristics, the curing state of phenolic resin can be obtained, which degree of cure ranges from 0.05 to 0.9. In isothermal curing process of phenolic resin, an exponential correlation between chemical shrinkage induced compressive strain and degree of cure of resin was identified, indicating that the real-time compressive strain is proportional to the degree of cure of phenolic resin. By evaluating real-time curing shrinkage levels, the estimation of curing degree of phenolic resin can be achieved utilizing exponential correlation of curing degree and curing shrinkage level.

Study on CO2 co-gasification of cellulose and high-density polyethylene via TG-FTIR and ReaxFF MD

CO2 co-gasification of solid waste and biomass presents an approach for the comprehensive utilization of waste materials, biomass and carbon dioxide. In this study, the CO2 co-gasification of cellulose and high-density polyethylene was explored utilizing TG-FTIR method and ReaxFF MD simulation. The thermal behavior, synergistic effect, volatile release characteristics, activation energy and reaction mechanism were thoroughly analyzed. The experimental findings indicated that CO2 co-gasification involved four stages: drying, cellulose pyrolysis, polyethylene pyrolysis and semi-coke gasification. Co-gasification inhibited cellulose pyrolysis but promoted polyethylene pyrolysis, with the most pronounced promoting effect occurring at 40% polyethylene content. The absorbance curve suggested that CO release was associated with cellulose pyrolysis and the reaction between cellulose coke and CO2, and C-H release was related to the pyrolysis of cellulose and polyethylene. Co-gasification alleviated the energy barrier, with the greatest effect occurring at 40% polyethylene content. The simulated results confirmed that the promotion of polyethylene pyrolysis was attributed to the connection of radicals from cellulose with polyethylene. Additionally, the combination of hydrocarbon radicals and hydrogen from polyethylene and cellulose contributed to gas production. This investigation provides insights into the thermochemical conversion characteristics for CO2 co-gasification of biomass and high-density polyethylene.

Facile synthesis of nanosized spinel high entropy oxide (FeCoNiCrMn)3O4 for efficient oxygen evolution reaction

The sluggish reaction kinetics of oxygen evolution reaction (OER) and the high price of noble metal catalysts hinder the wide application of water electrolysis for hydrogen generation. High-entropy oxides (HEOs) with multi-components and high entropy stabilized structures have attracted great research interests due to their efficient and durable performance in electrolytic water splitting reactions. However, the development of efficient HEO electrocatalysts are often hindered by the limited surface exposed active sites because high temperature is usually required to form a high entropy stabilized structure. Herein, a flaky high-entropy oxide with a spinel structure, (FeCoNiCrMn)3O4, was synthesized by using the sacrificial layered carbon template in situ prepared by the volatile reaction between ammonium sulfate and molten glucose. High-resolution TEM results show the as-prepared (FeCoNiCrMn)3O4 flakes are composed of nanosized HEO particles. The nanosized (FeCoNiCrMn)3O4 HEO electrocatalysts exhibit excellent OER activity, with an overpotential of 239 mV at 10 mA/cm2 and a Tafel slope of 52.4 mV/dec. The electrocatalyst has excellent stability. Even at a high current density of 100 mA/cm2, the activity remains unchanged during the stability test for 24 h. The results here shed a new light in the design and fabrication of highly efficient HEO electrocatalysts.

Stock volatility reactions to economic policy uncertainty: the moderating role of sentiment divergence

ABSTRACT What accounts for the inverse relationship between Chinese stock market volatility and policy uncertainty during some periods? We investigate the underlying factors contributing to this phenomenon. Our research suggests that sentiment divergence significantly diminish the positive impact of policy uncertainty on stock volatility. In some periods, the positive effect of policy uncertainty on stock volatility may be relatively weak, unable to counterbalance the negative influence of sentiment divergence. As a result, we observe a reverse movement of stock volatility and policy uncertainty during these periods. Notably, we find that the moderating effect of sentiment divergence can persist for up to 25 days, which we attribute to liquidity constraints. Our research also indicates that the effect of sentiment divergence is larger for liquid stocks or under poor market conditions. Through a range of endogeneity and robustness tests, we verify the validity of the findings.

Assessment of Cryogenic Coring to Preserve Vertical Distributions of Trichloroethylene and Reaction Products in an Aquitard

AbstractThere is not a clear understanding of the extent by which naturally occurring reactions can attenuate trichloroethene (TCE) and its daughter products within low permeability zones (LPZs), and addressing this knowledge gap requires advancement of methods to accurately measure in situ volatile chemical concentrations. In this study, a soil coring method that freezes the soil in‐situ (a.k.a., cryogenic coring) was utilized to measure depth‐discrete distributions of TCE and its volatile reaction products through a TCE‐impacted silty clay aquitard, and results were compared with those from adjacent soil cores taken using a conventional coring approach. Vertical concentration profiles of TCE, cis‐1,2‐dichloroethylene (DCE), vinyl chloride (VC), ethane, and methane were all compared between the two coring methods, and results indicate the two coring methods recovered statistically equivalent concentrations of volatiles across most depths of the fine‐grained cohesive clayey soil at the study site. Biotic reductive dechlorination was the dominant TCE reaction pathway at the site; several reduced gasses that are possible markers for abiotic reduction were detected, but their concentrations and intervals of occurrence were not sufficiently consistent to indicate whether they were from abiotic TCE reduction or unrelated biological processes. Overall, cryogenic coring yielded improved recovery of sand lenses compared to conventional coring, but offered no apparent benefits for improved recovery of TCE and its volatile reaction products in the low permeability aquitard material at the site.

Numerical investigation on pyrolysis and ignition of ammonia/coal blends during co-firing

Co-firing ammonia with coal is a promising and feasible technology for reducing coal-related carbon emissions. Pyrolysis and ignition of ammonia-coal blended fuels are the key steps for flame stability and boiler operation safety throughout the conversion process but remain unclear. In this work, an extended Euler–Lagrange framework coupled to detailed solid-phase pyrolysis kinetics and gas-phase reactions mechanism is introduced and validated against experimental results for ammonia-coal co-firing in a two-stage flat flame burner. First, the CRECK-S coal pyrolysis model was validated with TGA experiments and the CPD model at different heating rates to determine parameters for a competing two-step model for CFD simulations. Second, a detailed gas-phase mechanism with 116 species and 1513 elementary reactions was derived from the volatile and ammonia reaction mechanisms. Thirdly, the co-firing simulations were validated for the ignition delay time for various ammonia co-firing ratios. The results show that increasing the co-firing ratios from 0.0 to 1.0 results in gradually increasing ignition delay times in a low-oxygen atmosphere. Further analysis demonstrates that adding ammonia accelerates the coal particle heating rate due to the reduced coal particle number density and ammonia reaction induced gas-phase temperature increase, and thus the coal devolatilization rate is increased. The latter plays a dominant role. Hydrogen produced from ammonia pyrolysis is negligible, so ammonia predominantly participates in the ignition. Time scale analysis shows that homogeneous ignition is dominant during the ignition process. The presence of ammonia inhibits the inward oxygen diffusion and causes the reaction zone to move away from the pulverized coal particle flow. The oxygen diffusion inhibition and low reactivity of ammonia compared to volatiles lead to an increase in ignition delay time for ammonia co-firing, even though pulverized coal devolatilization is accelerated.

Application of Simultaneous and Coupled Thermal Analysis Techniques in Studies on the Melting Process, Course of Pyrolysis and Oxidative Decomposition of Fused Triazinylacetohydrazides.

The effect of the structure of promising antioxidant agents with prospective medical use, i.e., unsubstituted and para-substituted annelated triazinylacetic acid hydrazides, on their melting points, thermal stabilities, pyrolysis and oxidative decomposition stages and the type of volatiles emitted under heating with the use of DSC and TG/DTG/FTIR/QMS methods was evaluated and discussed. The melting point of the investigated compounds increased with an enhanced number of electrons (directly correlated with their molecular weight). Melting enthalpy values were determined and presented for all the studied compounds. The pyrolysis and oxidative decomposition processes of the analysed molecules consisted of several poorly separated stages, which indicated a multi-step course of the decomposition reactions. It was found that the thermal stability of the tested compounds depended on the type of substituent at the para position of the phenyl moiety or its absence. In both atmospheres used (air and helium), the thermal stability increased in relation to R as follows: -CH3 ≤ -OCH3 < -H < -OC2H5. In an inert atmosphere, it was higher by approx. 8-18 °C than in an oxidative atmosphere. The pyrolysis was connected with the emission of NH3, HCN, HNCO, HCONH2, HCHO, CO2, CO and H2O in the case of all the tested compounds, regardless of the substituent attached. In the case of the derivative containing the para-CH3 group, para-toluidine was an additional emitted aromatic product. In turn, emissions of aniline and alcohol (methanol or ethanol) for compounds with the para-OCH3 and para-OC2H5 groups, respectively, were confirmed. In oxidative conditions, the release of NH3, NO, HCN, HNCO, HCONH2, CO2, H2O and cyanogen (for all the compounds) and para-toluidine (for the para-CH3 derivative), aniline (for para-OCH3, para-OC2H5 and unsubstituted derivatives) and acetaldehyde (for the para-OC2H5 derivative) were clearly observed. No alcohol emissions were recorded for either compound containing the para-OCH3- or para-OC2H5-substitututed phenyl ring. These results confirmed that the pyrolysis and oxidative decomposition of the investigated annelated triazinylacetohydrazides occurred according to the radical mechanism. Moreover, in the presence of oxygen, the reactions of volatiles and residues with oxygen (oxidation) and the combustion process additionally proceeded.

Numerical Simulations of Gasification of Low-Grade Coal and Lignocellulosic Biomasses in Two-Stage Multi-Opposite Burner Gasifier

Thermochemical processes utilizing biomass demonstrate promising prospects for the generation of syngas. In this work, a gasification process employing combination of an indigenous low-grade coal with two distinct biomass sources, namely rice husk (RH) and wood sawdust (WS), was explored. The gasification of the selected feedstock was performed using a double-staged multi-opposite burner (MOB) gasifier. A 3D computational fluid dynamics (CFD) model was employed to analyze the effect of kinetic and diffusion rates on the overall gasification performance of an entrained flow biomass gasifier. DPM was employed to track the particles’ trajectory, while the gas phase was treated as the continuous phase, and its behavior was predicted using a standard k-epsilon turbulent model. To calculate both the homogeneous and heterogeneous reaction rates, the finite rate/eddy dissipation model was implemented. The findings indicate that the char conversion efficiency exceeded 95% across all instances. Among the different reaction schemes, scheme E (which involved complete volatile and char combustion reactions) produced better results in comparison with published results, with less than 1% error. Hence, scheme E was validated and utilized for the rest of the simulated cases. The feeding rate has an inverse effect on the overall performance of the gasifier. An increase in feed rate decreases the CO and H2 composition in syngas. The maximum CO value was observed to be 57.59% at a 1.0 O/C ratio with a 0.005 kg/s feed rate, and the maximum H2 value was observed to be 16.58% in the same conditions for Lakhra coal samples. In summary, Lakhra coal exhibited better performance than other biomass samples due to its better fixed carbon and volatiles in its composition.

A thematic analysis of code of ethics disclosures in SEC 8‐K Item 5.05

AbstractThe Securities and Exchange Commission requires the disclosure of changes to or waivers of corporate codes of ethics. Because the nature of amendments or waivers can vary, we expect the text of Item 5.05 to include different topics within different filings. We examine the population of these disclosures in Item 5.05 8‐K filings from 2004 to 2020. While previous studies utilized small samples (fewer than 50 observations) to examine limited aspects of these filings, we use the population of these filings from 2004 to 2020 (2121 8‐K filings) to elucidate the nature and details of the disclosures. We assess whether Latent Dirichlet Allocation—a computational linguistics technique—can help discern the underlying topics represented in filings. While the Securities and Exchange Commission identifies two topics—amendments and waivers—the Latent Dirichlet Allocation analysis reveals four topics (three related to amendments): (1) code updates and clarifications; (2) combining codes of conduct for all officers and employees, or splitting codes to include a code directly applicable to senior financial officers; (3) codes of ethics waivers; and (4) substantive code changes. The overall trend is for fewer 8‐Ks to be filed in recent years, with updates and clarifications becoming the predominant filing type. Our results further indicate that Item 5.05s related to updates and clarifications, and those related to combined or split codes, use fewer words and are more easily readable than those disclosing waivers or material code changes. Although we find no significant price reaction to Item 5.05 8‐K filings, we find significant trading volume and volatility reactions, suggesting that these disclosures could give rise to differences in opinion among investors, which is consistent with the US Senate's assertion that these disclosures are of interest to investors.

Thermodynamic behavior and kinetic analysis of carbothermal reduction process of low-grade oxysulfur lead–zinc ore

During the exploitation of sphalerite resources, a considerable amount of low-grade oxysulfur Pb–Zn deposits is generated, which poses a significant threat to the environment and soil and water conservation in mining areas. Therefore, low-grade Pb–Zn resources urgently require source emission reduction and appropriate utilization. This study applied a mineral technology and conducted X-ray diffraction and scanning electron microscopy–energy dispersive X-ray spectroscopy to investigate the phase transformation and the mechanism underlying the volatilization of Pb and Zn at different times and temperatures. The Pb–Zn volatilization kinetics of a low-grade oxysulfur Pb–Zn ore by a one-step pyrometallurgical process in an argon atmosphere was studied, and the effects of different temperature conditions on the Zn volatilization process were investigated. The results showed that the Zn-containing phase in the raw material was decomposed to ZnO and ZnS upon heating. Moreover, ZnO was reduced via carbothermal reduction, whereas ZnS was reduced via a CaO-assisted carbothermal reaction and volatilized in the form of gaseous Zn. In the Pb-containing phase, PbSO4 generated PbO, Pb, and PbS in the presence of Fe, FeS, and CaO. PbO was volatilized in the form of gaseous Pb through carbothermal reduction and interactions between PbS and PbO. The Pb–Zn volatilization reaction conformed to the shrinking core model with a constant size, and the volatilization-based removal of Pb and Zn process was controlled by internal diffusion. A macroscopic kinetic model of the reaction was established on the basis of experimental data. The apparent activation energy of Pb and Zn volatilization was 163.90 and 328.19 kJ/mol, respectively. This study promotes the utilization of the low-grade oxysulfur Pb–Zn ore through a pyrometallurgical method to provide theoretical support for large-scale industrial treatments.

Valorizing spent mushroom substrate into syngas by the thermo-chemical process

This study investigated the conversion of agricultural biomass waste (specifically, spent mushroom substrate) into syngas via pyrolysis. Carbon dioxide was used to provide a green/sustainable feature in the pyrolysis process. All the experimental data highlight the mechanistic role of carbon dioxide (CO2) in the process, demonstrated by the enhanced carbon monoxide (CO) yield from pyrolysis under CO2. Carbon dioxide was indeed reactive at ≥ 500 ˚C. Carbon dioxide was reduced and subsequently oxidized volatiles stemming from the thermolysis of spent mushroom substrate via the gas-phase reaction, thereby resulting in the enhanced formation of CO. Carbon dioxide radically diverted the carbon distribution patterns of the pyrogenic products, as more carbon in the oil was allocated to syngas by the gas-phase reaction of volatiles and CO2. To enhance the mechanistic role of CO2, a Ni-based catalyst was added to the pyrolysis process, which greatly accelerated the gas-phase reaction of volatiles and CO2.

Hybridization of the thermo-chemical process of polyvinyl chloride in the production of bioethanol using horse hay

The improper disposal of polyvinyl chloride (PVC) is hazardous to the environment. To rectify the inappropriate disposal of PVC, this study proposes a sustainable method to valorize hydrogen chloride (HCl) (from the thermolysis of PVC) in bioethanol (BE) production. Prior to saccharification, lignocellulosic biomass (horse hay) was treated with HCl. The optimized parameters for acid treatment were determined from a series of saccharification tests. In detail, the sugar recovery yield was 75 % after 2 % HCl, 120 °C, and 2 h treatment of horse hay. In addition, this study suggests that a nitrogen source is required during fermentation to enhance BE productivity. To valorize the residual materials from the saccharification of horse hay and dechlorination of PVC, they were pyrolyzed. Co-pyrolysis of the residues was performed in a CO2 gas environment. The gas-phase reaction of CO2 and volatiles stemming from the two residues was observed, which directly led to the enhanced generation of carbon monoxide (CO). These observations are attributed to the simultaneous redox mechanisms of CO2 and volatiles. To accelerate the reaction rate of the redox mechanisms, catalytic co-pyrolysis of the residues over Co/SiO2 was performed, and such attempts were confirmed by the enhanced formation of H2 and CO. This study highlights that the hybridization of the thermochemical process of PVC in the production of BE could be a viable approach for waste valorization.