Different Concentrations Of CO2 Research Articles

Effects of Co-doping on the microstructure and electrochemical performance of nickel vanadate (Ni3V2O8) electrode material for aqueous symmetric supercapacitor

Recently, there has been an increased focus on supercapacitors due to their reliable electrochemical energy storage capabilities. This study utilized an environmentally friendly facile hydrothermal method to prepare the nickel vanadate (NiVO) and cobalt-doped nickel vanadate (Co-doped Ni3V2O8) composite for supercapacitor applications. The prepared materials of pure and Co-doped Ni3V2O8 with different concentrations of Co (10 % and 15 %) were evaluated through three electrode assemblies. It is significant to note that although Co smoothed the surface of NiVO, most of the nickel vanadate crystals broke apart into tiny particles and increased the number of electroactive sites. Pure NiVO has a specific capacitance (Cs) of 1638.06 F/g at 5 mV/s. It has been observed that the electrochemical performance has been improved by adding Co 10 % and 15 % in NiVO. The 15 % Co-doped NiVO exhibits an outstanding Cs of 2641.99 F/g at a scan rate of 5 mV/s with a high capacitance retention of 98.14 % after 1k charge-discharges cycles. This excellent performance of the material is due to more electroactive sites and synergistic effects among Co and Ni in the composite. To further elaborate the electrochemical performance of 15 % Co-doped NiVO, it is employed for the fabrication of a symmetries supercapacitor (SSC) device, which shows that the fabricated device has a capacitance of 286 F/g at a current density (CD) of 0.5 A/g and high energy density of 39.7 Wh/kg at a power density of 333.33 W/kg. The symmetric device maintains a cyclic stability of 93.8 % while undergoing 5000 consecutive charge–discharge cycles at a current density of 10 A/g. Based on rigorous testing and analysis, these findings suggest that the prepared electrode material is reliable and suitable for implementation in forthcoming wearable electronic systems.

Evaluation of Elevated CO2 on Nutritional Quality of Green Gram for the Management of Callosobruchus chinensis (L.) during Storage

An experiment was conducted to study the assessment of nutritional quality parameters of green gram treated with elevated levels of carbon dioxide to manage Callosobruchus infestation during 2020-21 at Seed Entomology Laboratory, Seed Research and Technology Centre, College of Agriculture, Rajendranagar, Hyderabad, India. Nutritional quality of Callosobruchus chinensis infested green gram seeds exposed to four different concentrations of CO2 viz., 20, 40, 60 and 80 per cent was studied. The results revealed that the 80 per cent CO2 concentration maintained high carbohydrate content (62.93 per cent) and crude fat (4.51 per cent) besides less protein (25.26 per cent) content after two months of storage. The 80per cent CO2 treatment was consistently found to be the best treatment when it was retested in bulk quantity (25 kg of seed) after two months of storage period. High carbohydrate, crude fat content and low protein content were observed in all the CO2 treatments (20, 40, 60 and 80 per cent) when compared to untreated control. These findings suggest that using elevated CO2 levels could be a viable alternative to synthetic pesticides chemical fumigants for preserving green gram during storage.

Experimental study on the desorption behavior of high-volatile bituminous coals following CO2 and CH4 injection at various compositional ratios

CO2-ECBM (Enhanced Coalbed Methane recovery) offers the dual benefits of increasing methane production and reducing carbon emissions through sequestration. Previous studies have primarily focused on the competitive adsorption effects of different gas compositions during the CO2-ECBM. However, the dynamic changes in desorption volume, desorption strain, and gas composition for different compositional ratios of CO2/CH4 after injecting CO2 remain unclear. Therefore, high-volatile bituminous coals from the southern margin of the Junggar Basin are chosen for desorption experiments with five different compositional ratios of CO2/CH4. Desorption volume, desorption strain, and gas composition of the coal samples are monitored during the desorption process. Finally, the mechanism influencing the dynamic changes in gas composition during desorption is analyzed. The results indicate that as CO2 concentration increases, both desorption volume and desorption strain correspondingly increase. At the same desorption volume, a higher CO2 concentration results in greater desorption strain. For different compositional ratios of CO2/CH4, CH4 concentration gradually decreases while CO2 concentration gradually increases over desorption time. The concentration of the desorption gas is influenced by the initial CO2 concentration and the pore structure. Specifically, higher initial CO2 concentrations, better pore opening, and more developed mesopores and macropores lead to greater changes in composition concentrations during desorption. Different concentrations of CO2 all promote CH4 production, with higher CO2 concentrations enhancing CH4 production efficiency more significantly, especially for samples that are more difficult to produce. The research findings can provide guidance for the efficient production of CBM after CO2 injection.

Cu–Co bimetallic organic framework as effective adsorbents for enhanced adsorptive removal of tetracycline antibiotics

In this study, the removal effect of a new MOF-on MOF adsorbent based on Cu–Co bimetallic organic frameworks on tetracycline antibiotics (TCs) in water system was studied. The adsorbent (Cu-MOF@Co-MOF) were synthesized by solvothermal and self-assembly method at different concentrations of Co2+/Cu2+. The characterization results of SEM, XRD, XPS, FTIR and BET indicated that the MOF-on MOF structure of Cu-MOF@Co-MOF exhibited the best recombination and physicochemical properties when the molar ratio of Co2+: Cu2+ is 5:1. In addition, the Cu-MOF@Co-MOF have a high specific surface area and bimetallic clusters, which can achieve multi-target synergistic adsorption of TCs. Based on above advantages, Cu-MOF@Co-MOF provided a strong affinity and could efficiently adsorb more than 80% of pollutants in just 5 to 15 min using only 10 mg of the adsorbent. The adsorption capacity of tetracycline and doxycycline was 434.78 and 476.19 mg/g, respectively, showing satisfactory adsorption performance. The fitting results of the experimental data were more consistent with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating that the adsorption process of TC and DOX occurred at the homogeneous adsorption site and was mainly controlled by chemisorption. Thermodynamic experiments showed that Cu-MOF@Co-MOF was thermodynamically advantageous for the removal of TCs, and the whole process was spontaneous. The excellent adsorption capacity and rapid adsorption kinetics indicate the prepared MOF-on MOF adsorbent can adsorb TCs economically and quickly, and have satisfactory application prospects for removing TCs in practical environments. The results of the study pave a new way for preparing novel MOFs-based water treatment materials with great potential for efficient removal.

Effects of concentrated CO2 on the performance of a PBI/H3PO4 high temperature proton exchange membrane fuel cell

In this study, the impact of mimic reformate of formic acid decomposition on the anode polarization of HT-PEMFC is investigated under various operating conditions of the anode, including different concentrations of CO2, N2, CO, and humidification. Polarization curve and EIS measurements indicate that there is no significant difference (less than 5 mV when i < 0.4A/cm2) between the same concentrations of CO2 and N2 up to 75 vol%. No significant poisoning of the anode by CO2 (up to 75 vol%) has been observed, suggesting that the addition of concentrated CO2 acts more as a diluent than a poison. Upon separating the polarization effects, it is found that the oxygen reduction reaction (ORR) is a crucial step limiting the fuel cell performance, with cathodic activation losses reaching as high as 70 % at 0.8A/cm2. However, with 1 vol% CO in a H2/CO2 1/1 mixture, a significant poisoning effect on the fuel cell is observed. DRT (distribution of relaxation times) analyses reveal two peaks related to CO in high-frequency regions above 100 Hz associated with the anode polarization, with the peak integration being five times larger than in pure hydrogen. Humidification doesn't improve the voltage or mitigate CO poisoning. A one-dimensional flux model that includes the anode polarization is developed to analyze the polarizations for both cathode and anode under different concentrations of diluents, well describing the experimental results. When i < 0.8 A/cm2, the predicted values from the model closely match the measured values (within 5–10 mV). Calculations suggest that the anode polarization cannot be ignored, especially when the anode is fed with diluted gases.

Kinetic assessment of pulp mill-derived lime mud calcination in high CO2 atmosphere

The chemical pulping of biomass involves the recycling of calcium through the calcination of lime mud, which is mostly comprised of calcium carbonate (CaCO3). Lime mud decomposes under elevated temperatures to generate calcium oxide (CaO) and carbon dioxide (CO2), the kinetics of which are strongly influenced by the CO2 partial pressure and temperature. Oxy-fuel combustion and electrified lime kilns for lime mud calcination are intriguing methods to decarbonize this highly polluting operation within the biomass pulping industry. However, the high CO2 concentration in oxy-fuel and electrified calcination processes alters the kinetics and overall reactivity of lime mud. For the first time, a model-fitting method is used to determine the kinetic parameters for lime mud calcination under a wide range of temperatures (550 °C–1250 °C) and under different concentrations of CO2 (0 %, 15 %, 50 %, and 90 %). A kinetic model is developed that accurately predicts the reaction rates as a function of temperature and CO2 concentration. The apparent activation of energy for lime mud calcination is elevated under a high CO2 environment. Relative to inert gas (N2, Ar), the temperature window for calcination is much smaller under high CO2 environments. The presence of Na in lime mud does not seem to affect calcination under a high CO2 environment. Finally, particle size variation does not have a significant effect on calcination under a high CO2 environment.

Efficient and selective upgrading of biomass-derived furfural into 1,5 pentanediol by Co2+ etched ZIF-8 derived ZnCo layered double hydroxides nanoflake

Selective ring-opening hydrogenolysis of furfural (FF) to 1,5 pentanediol (1,5-PeD) is crucial for biomass valorization. However, achieving accurate bond-breaking is challenging. Herein, we report a facile method to synthesize layered double hydroxide nanoflake (ZnCo-LDH) mediated via Co2+ etching ZIF-8 with NaBH4 in water at ambient temperature. The structure, morphology, and chemical properties of synthesis catalysts with different concentrations of Co2+ were characterized. The results indicated a partial ZIF-8 structure in ZnCo-LDH, with increased Co2+ concentrations leading to catalyst agglomeration. Furthermore, the constitutive relationships between the catalyst’s properties and 1.5-PeD yields were established. Moreover, Co introduction altered the catalyst surface’s Brønsted and Lewis acids content. Density functional theory (DFT) indicated enhanced H2 adsorption and dissociation due to electro-transfer between Co and Zn species, with a tilted configuration favoring ring opening. Finally, a possible reaction mechanism was proposed. This work provides valuable insights for preparing ultrathin nanoflake ZnCo-LDH catalysts for biomass-derived furfur compound upgrading.

Research on etalon‐free CO2 measurement based on direct absorption signal fitting

AbstractThe emission of carbon dioxide (CO2) by thermal power plants is the main factor leading to the greenhouse effect. The measurement of CO2 is of great significance to carbon emission data statistics. In this paper, a measurement system based on tunable diode laser absorption spectroscopy (TDLAS) was built to measure the spectrum of CO2 near 1579 nm. To simplify the experimental system, a direct absorption signal fitting method is proposed to replace etalons for time‐frequency conversion. The method was applied to the measurement of four different concentrations of CO2 in the range of 7%–16%, and the measurement results were compared with the multipeak method, another etalon‐free method. The results show that the mean relative error of the measurement results is 4.23%, which is 1.76% lower than the measurement results of the multipeak method. The experimental research provides a feasible idea to simplify the CO2 measurement system based on TDLAS.

Development of CO2-sensitive antimicrobial bilayer films based on gellan gum and sodium alginate/sodium carboxymethyl cellulose and its application in strawberries

To effectively extend the shelf life of fruits meanwhile facilitating consumers to judge their freshness, in this work, a double-layer multifunctional film combining CO2 sensitivity and antibacterial properties was successfully prepared by adding methyl red (MR), bromothymol blue (BTB) into gellan gum (GG) as the sensing inner layer, and doping tannic acid (TA) into sodium alginate with sodium carboxymethyl cellulose (CMC) as the antimicrobial outer layer, which was applied to the freshness indication of strawberries. Microscopic morphology and spectral analysis demonstrated that the bi-layer films were fabricated successfully. The mechanical characteristics, thermal stability, water vapor resistance, and antibacterial capabilities of the bilayer films improved as TA concentration rose. They exhibited noticeable color changes at pH = 2–10 and different concentrations of CO2. Application of the prepared films to strawberries revealed that the GG-MB@SC-6%TA film performed most favorably under 4 °C storage conditions, not only monitoring strawberry freshness but also retaining high soluble solids and titratable acidity, resulting in a slight decrease in hardness and weight loss. Therefore, taking into account all of the physical-functional characteristics, the GG-MB@6%TA film has a broad application prospect for intelligent food packaging.

Comparative transcriptomic and metabolomics analysis of modified atmosphere responses in Tribolium castaneum (Coleoptera: Tenebrionidae).

Modified atmosphere is effective in controlling Tribolium castaneum Herbst, but it has adaptations. Comprehending the potential mechanism of resistance to T. castaneum in a modified atmosphere will help advance related management methods. This study conducted a comparative transcriptomic and metabolomic analysis to understand the physiological mechanism of T. castaneum in adapting to CO2 stress. Results showed that there were a large number of differentially expressed genes (DEGs) in T. castaneum treated with different concentrations of CO2. Gene ontology (GO) analysis revealed significant enrichment of DEGs mainly in binding, catalytic activity, cell, membrane, membrane part, protein-containing complex, biological regulation, and cellular and metabolic process. Kyoto Encyclopedia of Genes and Genomes analysis showed that different treatments had different effects on the metabolic pathways of T. castaneum. DEGs induced by 25% CO2 were involved in arginine and proline metabolism, and 50% air + 50% CO2 treatment affected most kinds of metabolic pathways, mainly the signal transduction pathway, including PI3K-Akt signaling pathway, AMPK signaling pathway, neurotrophin signaling pathway, insulin signaling pathway, and thyroid hormone signaling. Ribosome and DNA replication were enriched under high CO2 stress (75% and 95%). The metabolomics revealed that different concentrations of CO2 treatments might inhibit the growth of T. castaneum through acidosis, or they may adapt to anoxic conditions through histamine and N-acetylhistamine. Multiple analyses have shown significant changes in histamine and N-acetylhistamine levels, as well as their associated genes, with increasing CO2 concentration. In conclusion, this study comprehensively revealed the molecular mechanism of T. castaneum responding to CO2 stress and provided the basis for an effectively modified atmosphere in the T. castaneum.

Parametric Analysis of the Optimal CO content in A High Temperature PBI membrane

An experimental investigation is conducted on a high temperature, single cell PEM with three different concentrations of CO with the intent of establishing acceptable carbon monoxide content from reformates. Hydrogen of 99.997% purity is used as a baseline fuel while 2 and 5 % CO contents are tested at 150 oC to 190 oC. Results from these tests reveal significant and unacceptable reduction of cell performance with temperature below 150 oC while the performance characteristic of the tested blends tends to converge at higher temperatures around 190 oC and above. Prior work characterized the operation of the system over a sparse range of CO operational envelope. The current work will fill the gap to generate an operational envelope of CO percentage good for high temperature PEM fuel cell operation.

Impact of temperature on the role of Criegee intermediates and peroxy radicals in dimer formation from β-pinene ozonolysis

Abstract. Stabilized Criegee intermediates (SCIs) and organic peroxy radicals (RO2) are critical in atmospheric oxidation processes and secondary organic aerosol (SOA) formation. However, the influence of temperature on their corresponding reaction mechanisms in SOA formation is unclear. Through utilizing formic acid as a SCI scavenger and regulating the ratio of hydroperoxyl radials (HO2) to RO2 ([HO2]/[RO2]) from ∼ 0.3 to ∼ 1.9 using different concentrations of CO, the roles of RO2 and SCIs in SOA formation were investigated from 248 to 298 K, particularly for dimer formation in β-pinene ozonolysis. The SOA yield increased by 21 % from 298 to 273 K, while it decreased by 40 % from 273 to 248 K. Both changing [HO2]/[RO2] and scavenging SCIs significantly affect SOA yield and composition. SCI reactions accounted for more than 40 % of dimer and SOA mass formation for all temperatures. Increasing [HO2]/[RO2] inhibited dimer and SOA formation, and this inhibition became larger with decreasing temperature. Compared to low [HO2]/[RO2] (0.30–0.34), the dimer abundance at high [HO2]/[RO2] (1.53–1.88) decreased by about 31 % at 298 K and 70 % at 248 K. [HO2]/[RO2] has a specific impact on SCI-controlled dimers at lower temperatures by especially influencing the C9–SCI reactions with RO2. The dimers formed from C9–SCI reactions with RO2 were estimated to decrease by 61 % at high [HO2]/[RO2] compared to low [HO2]/[RO2] at 248 K. The high reactivity and substantial contribution to SOA of β-pinene-derived SCIs at lower temperatures observed in this study suggest that monoterpene-derived SCI reactions should be accounted for in describing colder regions of the atmosphere.

Effects of carbon dioxide concentration in modified atmosphere packaging on the shelf life and quality criteria of whole wheat bread during storage

AbstractThis study aimed to determine the effects of carbon dioxide concentration in modified atmosphere packaging (MAP) on the quality criteria and shelf life of whole wheat flour bread. Four different concentrations of CO2 and N2 gases (30% CO2 + 70% N2, 50% CO2 + 50% N2, 70% CO2:30% N2 and 100% CO2) were applied to the bread samples, which were packaged with PA/EVOH/LDPE (polyamide/ethylene vinyl alcohol/low‐density polyethylene). The samples were stored at room temperature (25°C ± 1°C) for 13 days. The control group was packaged using BOPP (bi‐oriented polypropylene) under atmospheric air as in traditional current use. The effects of MAP on headspace gas analysis, pH, moisture content, water activity, water‐holding capacity, blue value, hardness, total mould and yeast count and sensory evaluation were analysed on days 0, 3, 4, 5, 7, 10 and 13. The results showed that the most effective gas combination in extending the shelf life of whole wheat bread was 100% CO2, and its shelf life was 10 days, whereas it was only 3 days for the control group. Increasing concentrations of CO2 significantly affected mould and yeast growth. As the CO2 concentration increased, the bread exhibited higher water‐holding capacity and blue values, which are important indicators for bread staling. An improved preservation of sensory properties was observed in proportion to increasing CO2 concentrations. However, the CO2 gas concentration did not affect the hardness of the bread. Overall, the study suggests that MAP technology, particularly using 100% CO2, can effectively extend the shelf life of whole wheat flour bread without the need for preservatives, not only extending the microbiological shelf life but also increasing the sensory shelf life. The species that grew in air‐packaged samples were suppressed under modified atmosphere conditions and chalk mould fungi were the dominant and shelf life‐impacting species in the MAP samples. These findings could be beneficial in reducing bread wastage, which is a critical issue in today's society due to the limited shelf life of bread caused by rapid microbiological deterioration or staling.

Catalytic activity of Co (II)-porphyrin anchored onto polymeric support of electrospun polyacrylonitrile nanofiber: synthesis and efficient green oxidation of crystal violet dye with hydrogen peroxide

AbstractA novel method was explored in this study to address water contamination challenges by utilizing nanofiber mat-supported metalloporphyrin materials. Specifically, electrospinning was employed to create various compositions of polyacrylonitrile (PAN) mixed with different concentrations of Co(II) complex of tetrakis-5, 10, 15, 20 (4-hydroxyphenyl)porphyrin Co(II)TPHPP 1 anchored to chloroacetylated poly (p-hydroxy styrene) CAPS. These resulting nanofiber mat-supported metalloporphyrin materials were comprehensively analyzed using UV, FTIR spectrum, SEM, and TGA thermographs. The study found that the designed nanofibers acted as efficient catalysts for the oxidative breakdown of crystal violet (CV) dye using H2O2 in aqueous solutions. Among these materials, the nanofiber composed of a 1:1 ratio of PAN to Co(II)TPHPP/CAPS with a lower Co(II)TPHPP loading (NF6), demonstrated the highest catalytic activity, decomposing CV completely within 60 min. Various experiments were conducted to explore the effects of H2O2 concentration, catalyst dosage, and temperature on the catalytic degradation of CV with the NF6 nanofiber mat-supported metalloporphyrin. An interesting finding was the enhanced recovery and recyclability of the catalyst due to the immobilization of metalloporphyrin on chloroacetylated polymer-supported nanofiber mats. Remarkably, even after five cycles of reuse, there was no significant degradation in the catalytic activity of the recycled catalyst. This breakthrough highlights the potential of these materials in addressing water pollution challenges efficiently and sustainably.

A multimodal lithium niobate-based SAW gas sensor for accurate detection of carbon dioxide at elevated temperature

Carbon dioxide (CO2) detection is crucial for safety control, monitoring of the environment, and other industrial applications. The diverse fields of applications make the detection of CO2 a challenging task. In this paper, a study on a multimodal surface acoustic wave (SAW) CO2 sensing system was conducted to scrutinize the sensitivity of the lithium niobate-based multimodal SAW sensor towards CO2 with temperature compensation. The study focused on developing and evaluating a SAW temperature-compensated gas sensor using time-of-flight measurements. The sensor exhibited good repeatability and sensitivity toward different concentrations of CO2.

A new method for evaluation of nanotube growth kinetics in aerosol CVD

Aerosol chemical vapor deposition (CVD) – a particular case of floating catalyst CVD method with an extreme dilution of catalyst – has been demonstrated to be one of the most advanced one-stage and continuous techniques for the production of single-walled carbon nanotubes (SWCNTs) for various applications in electronics, optics, energy storage, etc. Nevertheless, rational scaling of the aerosol CVD reactor is often limited by a fundamental problem of tracking the growth kinetics, in particular, the nanotube growth rate and the catalyst deactivation rate. We propose a robust method for the assessment of nanotube growth kinetics (growth rate and catalyst lifetime) based on the analysis of the SWCNT film equivalent sheet resistance (R90) versus residence time (τ) dependencies. We have demonstrated identical trends of R90-vs-τ and length-vs-τ curves at different concentrations of CO2 used as a promoter in the Boudouard reaction- (CO-) based synthesis. As a result, we have revealed the mechanisms behind the CO2 effect on the catalyst deactivation rate not reported before. In particular, we observed an increase in CO2 concentration to provide a faster growth rate but an earlier catalyst deactivation. We believe this work might be useful for researchers from both academia and industry and facilitate more active development of aerosol CVD methods for the production of new materials.

Construction of a Numerical Model for Flow Flash Evaporation with Non-Condensable Gas

Flash evaporation processes are widely used in petroleum, food, chemical, power, and other industries to separate products or extract heat. The liquid is often entrained by non-condensing gas components. This study develops a multiphase, multicomponent, and pressure-driven phase-change-coupled model to numerically study water flash evaporation with non-condensing CO2. The model includes the mass, momentum, energy, volume of fluid (VOF), species transport, turbulence (RNG k-ε), modified phase-change Lee, and non-condensing CO2 release governing equations. The steam generation rate and mechanism for pure water and different concentrations of CO2 are considered. The results show that the numerical model can accurately predict the flash evaporation process and has high accuracy compared with the experimental data. Both the dissolved and entrained CO2 that are released can severely disturb the flow field, leading to an increase in the steam generation rate. Under a 1–10% volume concentration of dissolved CO2 and 0.0661–0.1688% mass concentration of entrained CO2, the maximum increase ratio of steam generation can reach 20%.

PSI Photoinhibition and Changing CO2 Levels Initiate Retrograde Signals to Modify Nuclear Gene Expression.

Photosystem I (PSI) is a critical component of the photosynthetic machinery in plants. Under conditions of environmental stress, PSI becomes photoinhibited, leading to a redox imbalance in the chloroplast. PSI photoinhibition is caused by an increase in electron pressure within PSI, which damages the iron-sulfur clusters. In this study, we investigated the susceptibility of PSI to photoinhibition in plants at different concentrations of CO2, followed by global gene expression analyses of the differentially treated plants. PSI photoinhibition was induced using a specific illumination protocol that inhibited PSI with minimal effects on PSII. Unexpectedly, the varying CO2 levels combined with the PSI-PI treatment neither increased nor decreased the likelihood of PSI photodamage. All PSI photoinhibition treatments, independent of CO2 levels, upregulated genes generally involved in plant responses to excess iron and downregulated genes involved in iron deficiency. PSI photoinhibition also induced genes encoding photosynthetic proteins that act as electron acceptors from PSI. We propose that PSI photoinhibition causes a release of iron from damaged iron-sulfur clusters, which initiates a retrograde signal from the chloroplast to the nucleus to modify gene expression. In addition, the deprivation of CO2 from the air initiated a signal that induced flavonoid biosynthesis genes, probably via jasmonate production.

Effect of CO2 on the preservation effectiveness of chilled fresh boneless beef knuckle in modified atmosphere packaging and microbial diversity analysis

To explore the effect of different concentrations of CO2 in modified atmosphere packaging (MAP) on the preservation shelf life of boneless beef knuckle (BBK), and to deeply study the changes in the bacterial community. In the controlled atmosphere combination, the proportion of O2 in each group is kept at 40%, CO2: 20%–45%, and N2: 15%–60%, the blank control group is set to 40%O2+0%CO2+60%N2. Sensory evaluation, headspace gas, total colony, and physicochemical indicators were measured at the 1st, 3rd, 5th, 7th, 9th, and 11th days of storage, respectively. The results showed that group 25%CO2+35%N2 had the longest shelf life is 9 days. In the analysis of the bacterial community, CO2 significantly inhibited the growth of Pseudomonas from the 3rd day onwards in the group 25%CO2+35%N2. After 4 days of storage, Lactobacillus was the main dominant bacterium, followed by Carnobacterium. Through KEGG metabolic pathway analysis, it was found that during the storage and preservation process, the expression levels of genes related to carbohydrate metabolism and amino acid metabolism in cold fresh BBK were higher than those in other metabolites.

Inhibition of insoluble HgS and HgO generation and promotion of easy-soluble HgCl2 production for the solution washing regeneration of mercury adsorbent in syngas

Inhibiting the generation of insoluble HgO and HgS, as well as promoting the generation of HgCl2 can significantly contribute to the solution washing regeneration of adsorbent for Hg removal in syngas. In this study, CeO2-MnO2/TiO2(Ce-Mn/Ti) was chosen as the Hg adsorbent, the fixed-bed test, Hg-TPD, and characterization test (including BET, SEM-EDS, and XPS) were conducted. Firstly, the effects of different concentrations of CO, H2, NH3, and HCl on the generation of HgS, HgO, and HgCl2 on adsorbent was investigated. Although the increase of CO, H2, and NH3 concentration can inhibit the generation of HgS and HgO to different extents, and the increase of HCl concentration can promote the production of HgCl2, but they will also lead to the increase in Hg concentration to varying degrees, indicating the adjustment on syngas components and concentrations is not a feasible method. Subsequently, the effects of different concentrations of modification reagent with CuCl2 were studied. The optimal impregnation ratio of CuCl2 was determined as 10%, in which the Hg removal efficiency in H2S atmosphere could reach over 97%, and almost of the Hg-containing product was easy-soluble HgCl2. The great advantage of impregnation modification of CuCl2 is attributed to the uniform and dense distribution of CuCl2, as well as the strong activity of CuCl2 itself towards Hg0 oxidation to HgCl2. The impregnation modification of CuCl2 can significantly improve the Hg removal efficiency, inhibit the generation of HgS and HgO, and promote the generation of HgCl2, which is verified as a feasible method to improve the solution washing regeneration of Hg adsorbent.