Addition Of Carbon Dioxide Research Articles

Investigation of the process of moisture loss during refrigerated storage of fish

The purpose of current work is to study the effect of carbon dioxide on the shrinkage of smoked fish and to develop a technical solution for the implementation of technology with the use of CO2 in fish trade. We use mackerel, flounder and crucian carp as test samples. The studies were carried out in two versions: storage of fish in a chamber under traditional conditions and with the addition of carbon dioxide (CO2) to the refrigerating chamber. The use of carbon dioxide gas during the storage of smoked fish leads to an increase in the water-holding capacity of the fish in comparison with the traditional storage method. In our proposed method of storage in a cold atmosphere with CO2, fish shrinkage is reduced. The carbonate ions well bind water molecules in the hydration shell due to positive hydration, which slows down the processes of hydrolysis and oxidation of lipids inside the subcutaneous layer and preserves the moisture-retaining capacity of tissues. Thus, the use of carbon dioxide in the storage of smoked fish reduces weight loss and does not affect the appearance of the fish.

Influence of the Composition of Solid Fuel on the Equilibrium Characteristics of a Gasification Process in the Mixtures of Oxygen and Carbon Dioxide

The gasification of solid fuels of different elemental compositions in O2/N2 and O2/CO2 mixtures was studied using equilibrium thermodynamic modeling. The dependences of process characteristics (temperature and the yield of carbon residue) on the composition of gasification agent and the stoichiometric ratio were calculated. The addition of carbon dioxide, on the one hand, promoted the conversion of carbon due to an increase in the concentration of gasifying agents and, on the other hand, decreased the process temperature due to an increase in heat capacity and an endothermic effect of the gasification reaction. The efficiency of using O2/CO2 mixtures for the gasification of fuels increased with the carbon content. The highest chemical efficiency of coke and coal gasification was achieved at an initial CO2 concentration of about 40–60 vol %.

Effects of simultaneous CO2 addition and biomass recycling on growth characteristics of microalgal mixed culture

AbstractBACKGROUNDThis study aims to investigate the effect of simultaneous carbon dioxide (CO2) addition and biomass recycling on specific performance parameters (including biomass productivity and harvestability, and species abundance) of the mixed culture of two freshwater microalgae species Chlorella vulgaris and Scenedesmus obliquus in a flat‐panel photobioreactor grown semicontinuously using secondary effluent urban wastewater as the culture medium. Recycling a portion of the gravity‐harvested biomass back to the system has positive effects on biomass productivity and harvestability by letting microalgal cells utilize more of the available light energy and promoting the dominance of settleable microalgal species of S. obliquus (owing to their large cell sizes) in the mixed culture. Furthermore, CO2 addition could supply the carbon limitation of urban wastewater and boost biomass production.RESULTSThe work confirmed that simultaneous CO2 addition and biomass recycling improved the biomass productivity by 314%, promoted the dominance of the larger algae species S. obliquus in the mixed culture by 38%, and increased the gravity sedimentation by 85% compared to the control that had no recycling and CO2 addition. Concerning the secondary effluent urban wastewater, the interaction of CO2 addition and biomass recycling was insignificant regarding the improvement in nutrient removal efficiency.CONCLUSIONThe findings proved the potential benefits of simultaneous biomass recycling and CO2 addition for reaching a high cell density, and demonstrated its potential for high biomass harvest efficiency in microalgae‐based wastewater treatment systems. © 2021 Society of Chemical Industry (SCI).

A fast Gaussian process-based method to evaluate carbon deposition during hydrocarbons reforming

Biogas, landfill gas, associated petroleum gas, and other tail gases accompanying various industrial processes are potential sources of hydrogen and carbon monoxide for solid oxide fuel cells via the reforming process. As these gases contain heavy hydrocarbons, fine-tuning of steam and carbon dioxide addition and specific temperature control are necessary to avoid carbon deposition during the reforming process. Numerical simulation plays a crucial role in designing miniaturized steam reforming reactors and optimal working conditions. All simulations of reforming processes must account for carbon deposition. The methods commonly seen in the open literature include Gibbs free energy minimization or parametric equations formalism. This paper utilizes Gaussian process regression as a tool for making predictions about which reforming parameters are suitable for carrying out this process without the danger of damaging the catalyst due to a carbon formation. Parametric equations formalism and Gibbs free energy minimization involve either the minimization of objective function or a search for roots of nonlinear functions. These tasks are sensitive to a choice of the starting points of the algorithm — wrong choice of starting points could lead to numerical instability. Unlike conventional methods, the Gaussian process regression approach bypasses the computation of equilibrium composition. It predicts carbon formation tendencies directly from the initial conditions which ensure stability.

Effects of carbon dioxide on the combustion characteristics of the laminar premixed n-heptane/air flames at elevated pressures

In this paper, the laminar combustion characteristics of n-heptane/carbon dioxide/air flames are numerically investigated by using the Chemkin/Premix Code and LLNL v3.1 mechanism. The equivalence ratios vary from 0.8 to 1.4 at the initial temperature of 298 K. The initial pressure is set as 1, 2, 5, 10, 20 atm. Laminar burning velocity (LBV), adiabatic flame temperature (AFT), net heat release rate (NHRR) and the mole fractions of H, O, OH, CO at stoichiometric ratio are studied with carbon dioxide (CO2) addition. Meanwhile, temperature sensitivity and rate of production (ROP) are analyzed. In addition, the physical and chemical effects of CO2 are investigated by introducing fictitious carbon dioxide (FCO2).The results show that with the increase of initial pressures, LBV decreases, AFT and NHRR increase, the peaks of intermediate products such as H, O, OH and CO decrease. The promoting effect of elementary reactions on temperature is greatly enhanced, while the inhibiting effect is slightly enhanced. With the increase of CO2 doping ratios, LBV, AFT and NHRR decrease, while the peaks of H, O, OH, CO increase first and then decrease. The promoting and inhibiting effects of elementary reactions on temperature are enhanced. Both physical and chemical effects of CO2 inhibit the combustion of n-heptane, where physical effect dominates. The total ROPs of H, O, OH change from consuming to producing, while the total ROP of CO is opposite.

Preparation of Liposomes from Soy Lecithin Using Liquefied Dimethyl Ether.

We investigated a method to prepare liposomes; soy lecithin was dissolved in liquefied dimethyl ether (DME) at 0.56 MPa, which was then injected into warm water. Liposomes can be successfully prepared at warm water temperatures above 45 °C. The transmission electron microscopy (TEM) images of the obtained liposomes, size distribution, ζ-potential measurements by dynamic light scattering and the amount of residual medium were compared by gas chromatography using the conventional medium, diethyl ether. The size of the obtained liposomes was approximately 60–300 nm and the ζ-potential was approximately −57 mV, which was almost the same as that of the conventional medium. Additionally, for the conventional media, a large amount remained in the liposome dispersion even after removal by depressurization and dialysis membrane treatment; however, liquefied DME, owing to its considerably low boiling point, was completely removed by depressurization. Liquefied DME is a very attractive medium for the preparation of liposomes because it does not have the toxicity and residue problems of conventional solvents or the hazards of ethanol addition and high pressure of supercritical carbon dioxide; it is also environmentally friendly.

Polyethylenimine-based catalysts for the addition of carbon dioxide to epoxides: an effect of substituents

Polyethylenimine-based catalysts for the addition of carbon dioxide to epoxides: an effect of substituents

Iodine as an efficient and available activator of sodium and potassium halides in carbon dioxide addition to epoxides

Iodine as an efficient and available activator of sodium and potassium halides in carbon dioxide addition to epoxides

Replacing liquid fossil fuels and hydrocarbon chemical feedstocks with liquid biofuels from large-scale nuclear biorefineries

Liquid fossil fuels (1) enable transportation and (2) provide energy for mobile work platforms and (3) supply dispatchable energy to highly variable demand (seasonal heating and peak electricity). We describe a system to replace liquid fossil fuels with drop-in biofuels including gasoline, diesel and jet fuel. Because growing biomass removes carbon dioxide from the air, there is no net addition of carbon dioxide to the atmosphere from burning biofuels. In addition, with proper management, biofuel systems can sequester large quantities of carbon as soil organic matter, improving soil fertility and providing other environmental services. In the United States liquid biofuels can potentially replace all liquid fossil fuels. The required system has two key features. First, the heat and hydrogen for conversion of biomass into high-quality liquid fuels is provided by external low-carbon energy sources--nuclear energy or fossil fuels with carbon capture and sequestration. Using external energy inputs can almost double the energy content of the liquid fuel per unit of biomass feedstock by fully converting the carbon in biomass into a hydrocarbon fuel. Second, competing effectively with fossil fuels requires very large biorefineries—the equivalent of a 250,000 barrel per day oil refinery. This requires commercializing methods for converting local biomass into high-density storable feedstocks that can be economically shipped to large-scale biorefineries.

Beyond the farm: Making edible protein from CO2 via hybrid bioinorganic electrosynthesis

Beyond the farm: Making edible protein from CO2 via hybrid bioinorganic electrosynthesis

Evaluation of Chemical Kinetic Mechanisms for Methane Combustion: A Review from a CFD Perspective

Methane is an important fuel for gas turbine and gas engine combustion, and the most common fuel in fundamental combustion studies. As Computational Fluid Dynamics (CFD) modeling of combustion becomes increasingly important, so do chemical kinetic mechanisms for methane combustion. Kinetic mechanisms of different complexity exist, and the aim of this study is to review commonly used detailed, reduced, and global mechanisms of importance for CFD of methane combustion. In this review, procedures of relevance to model development are outlined. Simulations of zero and one-dimensional configurations have been performed over a wide range of conditions, including addition of H2, CO2 and H2O, and the results are used in a final recommendation about the use of the different mechanisms. The aim of this review is to put focus on the importance of an informed choice of kinetic mechanism to obtain accurate results at a reasonable computational cost. It is shown that for flame simulations, a reduced mechanism with only 42 irreversible reactions gives excellent agreement with experimental data, using only 5% of the computational time as compared to the widely used GRI-Mech 3.0. The reduced mechanisms are highly suitable for flame simulations, while for ignition they tend to react too slow, giving longer than expected ignition delay time. For combustible mixtures with addition of hydrogen, carbon dioxide, or water, the detailed as well as reduced mechanisms generally show as good performance as for the corresponding simulations of pure methane/air mixtures.

Morphometric and growth responses of Enhalus acoroides seedlings under carbon dioxide enrichment: An experimental assessment

It is predicted that the concentration of carbon dioxide in the ocean will continue to increase. This phenomenon certainly has an impact on the sustainability of the marine ecosystem, including the seagrass ecosystem. This study aims to determine the effect of carbon dioxide on the morphometrics and growth of E. acoroides seedling. This study was an experimental study where the seeds from the fruit were grown in a controlled environment for two months. There are two treatments, first treatment with the addition of carbon dioxide and second treatment without the addition of carbon dioxide. The results of this study indicate that there is significant result from the two treatments given. Seagrass seeds that grow on treatment with carbon dioxide gas generally have shorter morphological characteristics as well as their growth.

Sodium and potassium halides as catalysts for the addition of carbon dioxide to epoxides: the effect of co-solvents

Sodium and potassium halides as catalysts for the addition of carbon dioxide to epoxides: the effect of co-solvents

Synergistic catalysis of metalloporphyrins and phosphonium ionic liquids for the efficient transformation of CO2 under ambient conditions

Synergistic effect between different functional groups is of significant influence on the activity of catalysts, especially for bi- or multi-component catalysts. Herein, a binary catalyst composing of metalloporphyrin (MPP) and phosphonium ionic liquid (PIL) is developed. The influence of substitution groups in both MPP and PIL on the cycloaddition addition of carbon dioxide and epoxides was comprehensively studied. The results demonstrated that the introduction of both electron-donating and electron-withdrawing functional groups in 5,10,15,20-tetraphenylporphyrin (TPP) framework was unfavorable to CO2 transformation. Moreover, PIL cocatalyst with longer alkyl group could enhance the catalytic activity obviously. When Co3+ was used as the metal active center, the binary catalyst system (TPP/Ph3PHexBr) could endow cyclic carbonate with a quantitative yield under the ambient condition of 50 °C and 1 atm CO2 pressure. The turnover frequency (TOF) value could also be as high as 191.3 h–1. Our founding thus provides an insight into the design of binary catalysts for efficient transformation of CO2.

Unsteady propagation of detonation with multi-stage heat release

This work numerically studies the propagation characteristics of detonation waves with multi-stage heat releases (MSHR) for stoichiometric dimethyl ether/oxygen (DME/O2) mixtures with carbon dioxide (CO2) addition. Results show that detonation with MSHR is intrinsically unstable and will develop to a new mode. It is found that in the mixtures with mu lti-stage heat release the steady structure on the scales predicted by the ZND theory cannot exist and evolves into a detonation wave with much thinner structure through the particular paths via which the ZND detonation losses its stability. For different MSHR features induced by CO2 addition, two detonation development modes with double- and single-head structures are observed, with the former controlled by the merging of second- and third-stage heat release, while the latter triggered by the second-stage heat release with the fastest heat release rate.

Reversible Addition of Carbon Dioxide to Main Group Metal Complexes at Temperatures about 0 °C.

The reaction of dialane [LAl-AlL] (1; L=dianion of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene, dpp-bian) with carbon dioxide results in two different products depending on solvent. In toluene at temperatures of about 0 °C, the reaction gives cycloadduct [L(CO2 )Al-Al(O2 C)L] (2), whereas in diethyl ether, the reaction affords oxo-bridged carbamato derivative [L(CO2 )(Et2 O)Al(μ-O)AlL] (3). The DFT and QTAIM calculations provide reasonable explanations for the reversible formation of complex 2 in the course of two subsequent (2+4) cycloaddition reactions. Consecutive transition states with low activation barriers were revealed. Also, the DFT study demonstrated a crucial effect of diethyl ether coordination to aluminium on the reaction of dialane 1 with CO2 . The optimized structures of key intermediates were obtained for the reactions in the presence of Et2 O; calculated thermodynamic parameters unambiguously testify the irreversible formation of the product 3.

The role of carbonate mineral dissolution in turbidity reduction in an oil sands end pit lake

Surface water turbidity from dispersed clay particles can hinder the development of aquatic ecosystems. One of the primary objectives for proposed oil sands end pit lakes is that they support ecological functions and lake-specific wildlife habitat. However, high surface water turbidity has been observed in the Base Mine Lake cap water, the first full-scale demonstration oil sands end pit lake. Our previous study showed that adjusting the solution pH through carbon dioxide (CO2) addition reduced surface water turbidity in oil sands tailings. Carbonate minerals such as calcite and dolomite were also previously identified in tailings, and thus the goal of this study was to determine the effect of calcite and dolomite dissolution through CO2-mediated pH reduction on turbidity and the stability of suspended clay particles. Calcite dissolution resulted in ∼99% reduction of turbidity. The suspended clay particle stability was analyzed using DLVO (Derjaguin-Landau-Verwey-Overbeek) theory with water chemistry data from this column study. An inverse correlation was observed between the amount of dolomite and the energy barrier values on day 42 of the experiment. These results suggest CO2-mediated calcite dissolution changes the water chemistry and is the most promising treatment condition for the settlement of suspended tailings particles.

Ammonia production using iron nitride and water as hydrogen source under mild temperature and pressure

Ammonia generation was studied in the reaction between water and nitrogen-containing iron at 323 K and atmospheric pressure. Similar to metallic Fe, the interstitial compound Fe3N reduced water through Fe oxidation to produce hydrogen gas, while the N combined with atomic hydrogen to produce ammonia as a byproduct. The addition of carbon dioxide to this system accelerated the reaction with concomitant consumption of carbon dioxide. The promoted ammonia production upon addition of carbon dioxide can be attributed to the generation of atomic hydrogen from the redox reaction of carbonic acid and Fe, as well as removal of used Fe from the reaction system through the formation of a soluble carbonato complex. When carbonate was added to the reaction system, the production rates of ammonia and hydrogen increased further. The results here confirmed that ammonia can be synthesized from iron nitride under mild conditions by utilizing carbon dioxide.

The effects of addition of carbon dioxide and water vapor on the dynamic behavior of spherically expanding hydrogen/air premixed flames

Utilizing efficiently and securely hydrogen as clean energy source, it is required not only to analyze the experimental data under a certain condition but also to create the mathematical model for the prediction of flame propagation velocity under various conditions. Thus, it is significant to understand the characteristics of dynamic behavior of hydrogen/air premixed flames and to elucidate the effects of addition of inert gas, i.e. carbon dioxide CO2 and water vapor H2O. We performed the experiments of hydrogen explosion in two types of closed chambers to observe spherically expanding flames using Schlieren photography. Wrinkles on the flame surface were clearly observed in low equivalence ratios. Analyzing the Schlieren images, the flame propagation velocity depending on the flame radius was obtained. Increasing the addition of inert gas, the propagation velocity decreased, especially in the case of CO2 addition. The propagation velocity increased monotonically as the flame radius became larger. The appearance of flame acceleration was found, which was caused by the evolution of wrinkles on the flame surface. Moreover, the Markstein length decreased as the concentration of inert gas became higher, indicating that the addition of inert gas promoted the instability of hydrogen flames. Furthermore, the wrinkling factor, closely related with the increment in propagation velocity, decreased as the inert-gas concentration became higher. The wrinkling factor normalized by the propagation velocity of flat flame increased, on the other hand, under the conditions of high inert-gas concentration, except for near the quenching conditions. This indicated that the addition of CO2 or H2O promoted the unstable motion of hydrogen flames, which could be due to the enhancement of the diffusive-thermal effect. Based on the characteristics of dynamic behavior of hydrogen flames, the parameters used in the mathematical model on propagation velocity including flame acceleration was obtained, and then the flame propagation velocity under various conditions was predicted.

Geological Society of London Scientific Statement: what the geological record tells us about our present and future climate

Geology is the science of how the Earth functions and has evolved and, as such, it can contribute to our understanding of the climate system and how it responds to the addition of carbon dioxide (CO2) to the atmosphere and oceans. Observations from the geological record show that atmospheric CO2 concentrations are now at their highest levels in at least the past 3 million years. Furthermore, the current speed of human-induced CO2 change and warming is nearly without precedent in the entire geological record, with the only known exception being the instantaneous, meteorite-induced event that caused the extinction of non-bird-like dinosaurs 66 million years ago. In short, whilst atmospheric CO2 concentrations have varied dramatically during the geological past due to natural processes, and have often been higher than today, the current rate of CO2 (and therefore temperature) change is unprecedented in almost the entire geological past. The geological record shows that changes in temperature and greenhouse gas concentrations have direct impacts on sea-level, the hydrological cycle, marine and terrestrial ecosystems, and the acidification and oxygen depletion of the oceans. Important climate phenomena, such as the El Nino–Southern Oscillation (ENSO) and the monsoons, which today affect the socio-economic stability and food and water security of billions of people, have varied markedly with past changes in climate. Climate reconstructions from around the globe show that climate change is not globally uniform, but tends to exhibit a consistent pattern, with changes at the poles larger than elsewhere. This polar amplification is seen in ancient warmer-than-modern time intervals like the Eocene epoch, about 50 million years ago and, more recently, in the Pliocene, about 3 million years ago. The warmest intervals of the Pliocene saw the disappearance of summer sea ice from the Arctic. The loss of ice cover during the Pliocene was one of the many rapid climate changes observed in the record, which are ften called climate tipping points. The geological record can be used to calculate a quantity called Equilibrium Climate Sensitivity, which is the amount of warming caused by a doubling of atmospheric CO2, after various processes in the climate system have reached equilibrium. Recent estimates suggest that global mean climate warms between 2.6 and 3.9°C per doubling of CO2 once all slow Earth system processes have reached equilibrium. The geological record provides powerful evidence that atmospheric CO2 concentrations drive climate change, and supports multiple lines of evidence that greenhouse gases emitted by human activities are altering the Earth’s climate. Moreover, the amount of anthropogenic greenhouse gases already in the atmosphere means that Earth is committed to a certain degree of warming. As the Earth’s climate changes due to the burning of fossil fuels and changes in land-use, the planet we live on will experience further changes that will have increasingly drastic effects on human societies. An assessment of past climate changes helps to inform policy decisions regarding future climate change. Earth scientists will also have an important role to play in the delivery of any policies aimed at limiting future climate change.