Protic ionic liquids have been regarded as promising materials to capture CO2, because they can be easily synthesized with an attractive capacity. In this work, we studied the CO2 absorption mechanism by protic ionic liquids (ILs) composed of diamino protic cations and azolide anions. Results of 1H nuclear magnetic resonance (NMR), 13C NMR, 2-D NMR and fourier-transform infrared (FTIR) spectroscopy tests indicated that CO2 reacted with the cations rather than with the anions. The possible reaction pathway between CO2 and azolide-based protic ILs is proposed, in which CO2 reacts with the primary amine group generated from the deprotonation of the cation by the azolide anion.

The simulation of carbon dioxide (CO2)-methane (CH4) mixed gas adsorption and the selectivity on zeolite 4A using Aspen Adsorption were studied. The influence of temperature ranging from 273 to 343 K, pressure up to 10 bar and various compositions of CO2 in the binary system were simulated. The findings of the study demonstrate that the models are accurate. In addition, the effects of various key parameters such as temperature, pressure, and various compositions of binary gases were investigated. The highest CO2 and CH4 adsorption are found at 273 K and 10 bar in the Langmuir isotherm model with 5.86 and 2.88 mmol/g, respectively. The amount of CO2 adsorbed and the selectivity of the binary mixture gas depends on the composition of CO2. The kinetics of adsorption for pure components of CO2 at high temperatures can reach saturation faster than CH4. The influence of the physical properties of zeolite 4A on kinetic adsorption were also studied, and it was observed that small adsorbent par... [more]

The main purposes of this project are to assess and to optimize the solubility of carbon dioxide (CO2) in an aqueous 30 wt% monoethanolamine-tetrabutylphosphonium methanesulfonate (MEA-[TBP][MeSO3]) new hybrid solvent. In this study, the viscosity and density of aqueous MEA-[TBP][MeSO3] hybrid solvents containing different amounts of [TBP][MeSO4] were determined. Meanwhile, Fourier Transform-Infrared (FT-IR) Spectroscopy was used to determine the presence of carbamate in aqueous MEA-[TBP][MeSO3] to prove that CO2 was absorbed by aqueous MEA-[TBP][MeSO3]. Response Surface Methodology (RSM) based on central composite design (CCD) was used to design the experiments and explore the effects of three independent parameters on the solubility of CO2 in aqueous MEA-[TBP][MeSO3]. The three independent parameters are concentration of [TBP][MeSO3] (2−20 wt.%), temperature (30−60 °C) and pressure of CO2 (2−30 bar). The experimental data was found to fit a quadratic equation using multiple regressio... [more]

In this work, a lipophilic ophthalmic drug, lutein, has been entrapped in liposomes, using a supercritical assisted process. Effects of pressure, temperature, and drug to lipid ratio variation were studied on mean diameters and lutein encapsulation efficiency. Liposomes with diameters between 153 ± 38 and 267 ± 56 nm were produced, and lutein encapsulation efficiencies between 86.5 ± 0.4% and 97.8 ± 1.2% were obtained. A Scanning Electron Microscope confirmed spherical shape and mean dimensions of vesicles. The variation of temperature for the production of liposomes showed a significant impact on lutein retention time in the double lipidic layer. Lutein drug release from liposomes produced at 35 °C ended in almost 4.5 days; whereas, liposomes produced at 40 °C showed a faster lutein release in 3 days; then, vesicles obtained at 45 °C released their lutein content in only 2 days. Drug release raw data were well-fitted using Weibull model (R2 up to 99%).

The effective separation of CO2 and CH4 mixtures is essential for many applications, such as biogas upgrading, natural gas sweetening or enhanced oil recovery. Membrane separations can contribute greatly in these tasks, and innovative membrane materials are being developed for this gas separation. The aim of this work is the evaluation of the potential of two types of highly CO2-permeable membranes (modified commercial polydimethylsiloxane and non-commercial ionic liquid−chitosan composite membranes) whose selective layers possess different hydrophobic and hydrophilic characteristics for the separation of CO2/CH4 mixtures. The study of the technical performance of the selected membranes can provide a better understanding of their potentiality. The optimization of the performance of hollow fiber modules for both types of membranes was carried out by a “distance-to-target” approach that considered multiple objectives related to the purities and recovery of both gases. The results demonst... [more]

Argon oxygen decarburization stainless steel slag (AOD slag) has high mineral carbonation activity. AOD slag carbonation has both the resource utilization of metallurgical waste slag and the carbon reduction effect of CO2 storage. This paper aimed to study carbonation reaction characteristics of AOD slag. Under the slurry-phase accelerated carbonation route, the effect of stirring speed (r) and reaction temperature (T) on AOD slag’s carbonation was studied by controlling the reaction conditions. Mineral composition analysis and microscopic morphology analysis were used to explore the mineral phase evolution of AOD slag during the carbonation process. Based on the unreacted core model, the kinetic model of the carbonation reaction of AOD slag was analyzed. The results showed that the carbonation ratio of AOD slag reached its maximum value of 66.7% under the reaction conditions of a liquid to solid ratio (L/S) of 8:1, a CO2 partial pressure of 0.2 MPa, a stirring speed of 450 r·min−1, an... [more]

Currently, one of the biggest concerns of human beings is greenhouse gas emissions, especially carbon dioxide emissions in developed and under-developed countries. In this study, connectionist models including LSSVM (Least Square Support Vector Machine) and evolutionary methods are employed for predicting the amount of CO 2 emission in six Latin American countries, i.e., Brazil, Mexico, Argentina, Peru, Chile, Venezuela and Uruguay. The studied region is modelled based on the available input data in terms of million tons including oil (million tons), gas (million tons oil equivalent), coal (million tons oil equivalent), R e w (million tons oil equivalent) and Gross Domestic Product (GDP) in terms of billion U.S. dollars. Moreover, the available patents in the field of climate change mitigation in six Latin American countries, namely Brazil, Mexico, Argentina, Peru, Chile, Venezuela and Uruguay, have been reviewed and analysed. The results show that except Venezuela, a... [more]

Clean methanol can play an important role in achieving net zero emission targets by decarbonizing the energy and chemical sectors. Conventionally, methanol is produced by using fossil fuel as raw material, which releases a significant amount of greenhouse gases (GHGs) into the environment. Clean methanol, which is produced by hydrogen (H2) from renewable sources (green H2) and captured carbon dioxide (CO2), is totally free from the influence of fossil fuel. Due to its vast applications, clean methanol has potential to substitute for fossil fuels while preventing further GHGs emissions. This review addresses the feasibility of producing clean methanol from renewable resources, i.e., green H2 and captured CO2. Availability of these raw materials is the main factor involved in establishing the circular economy of methanol, therefore, their potential sources and the possible pathways to access these sources are also summarized. Renewable energy sources such as solar, wind and biomass shoul... [more]

The enhancement of mass transfer is very important in CO2 absorption, and a rotating zigzag bed (RZB) is a promising device to intensify the gas−liquid mass transfer efficiency. In this study, the mass transfer characteristics in an RZB in relation to the overall gas-phase volumetric mass-transfer coefficient (KGa) were investigated with a CO2−NaOH system. A mathematical model was established to illustrate the mechanism of the gas−liquid mass transfer with irreversible pseudo-first-order reaction in the RZB. The effects of various operating conditions on KGa were examined. Experimental results show that a rise in the liquid flow rate, inlet gas flow rate, rotational speed, absorbent temperature, and absorbent concentration was conducive to the mass transfer between gas and liquid in the RZB. It was found that the rotational speed had the largest impact on KGa in the RZB. The KGa predicted by the model agreed well with that by the experiments, with deviations generally within 10%. There... [more]

Chemical absorbents with low-energy requirements have become the primary focus of the research on CO2 capture from flue gas in power plants. To verify the absorption performance of the NICE absorbent developed by the National Institute of Clean-and-Low-Carbon Energy in China, a performance optimization test was conducted in Zhejiang University’s pilot-scale platform, and the effects of the liquid−gas ratio, regeneration pressure, rich liquid fractional flow, and interstage cooling on the absorption performance and regeneration energy consumption were investigated. The results showed that in the CO2 pilot test, the optimized minimum regeneration energy consumption was 2.85 GJ/t CO2, and the corresponding process parameters were as follows: a liquid−gas ratio of 1.82 L/m3, regeneration pressure of 191 kPa, an interstage cooling temperature of 40 °C, and a rich liquid fractional flow ratio of 0.18. This study preliminarily verified the low-energy consumption performance of the NICE absorb... [more]

In this work, 2099 experimental data of binary systems composed of CO2 and ionic liquids are studied to predict solubility using a multilayer perceptron. The dataset includes 33 different types of ionic liquids over a wide range of temperatures, pressures, and solubilities. The main objective of this work is to propose a procedure for the prediction of CO2 solubility in ionic liquids by establishing four stages to determine the model parameters: (1) selection of the learning algorithm, (2) optimization of the first hidden layer, (3) optimization of the second hidden layer, and (4) selection of the input combination. In this study, a bound is set on the number of model parameters: the number of model parameters must be less than the amount of predicted data. Eight different learning algorithms with (4,m,n,1)-type hidden two-layer architectures (m = 2, 4, …, 10 and n = 2, 3, …, 10) are studied, and the artificial neural network is trained with three input combinations with three combinat... [more]

Viscosity, density, and interfacial tension of three binary systems (carbon dioxide−isopropanol, argon−isopropanol, and sulphur hexafluoride−isopropanol) were measured at temperatures of 313.15 K and 333.15 K and at pressures up to 100 bar for carbon dioxide, and for argon and sulphur hexafluoride up to 500 bar. A vibrating tube densimeter method has been used for density measurements and a variable-volume high-pressure optical view cell with some modifications for the other measurements. The results showed that pressure does not have a high impact on viscosity. Density is found to be a linear function of pressure and temperature and the densities of the investigated binary systems increase with pressure and decrease with temperature. Interfacial tension decreased with the elevated pressure at a constant temperature for all the investigated systems. Accurate prediction of thermodynamic and mass transfer data is fundamental in various engineering and industrial operations to design proc... [more]

The surface exchange and bulk transport of oxygen are highly relevant to ceria-based redox materials, which are envisaged for the solar thermochemical splitting of carbon dioxide in the future. Experimental investigations of oxygen isotope exchange on CeO2-δ, Ce0.9M3+0.1O1.95-δ (with M3+ = Y, Sm) and Ce0.9M4+0.1O2-δ (with M4+ = Zr) samples were carried out for the first time utilizing oxygen-isotope-enriched C18O2 gas atmospheres as the tracer source, followed by Secondary Ion Mass Spectrometry (SIMS), at the temperature range 300 ≤ T ≤ 800 °C. The experimental K˜O and D˜O data reveal promising results in terms of CO2 splitting when trivalent (especially Sm)-doped ceria is employed. The reaction temperatures are lower than previously proposed/reported due to the weak temperature dependency of the parameters K˜O and D˜O. The majority of isotope exchange experiments show higher values of K˜O and D˜O for Sm-doped cerium dioxide in comparison to Y-doped and Zr-doped ceria, as well as nomin... [more]

The analysis of real-world emissions is necessary to reduce the emissions of vehicles during on-road driving. In this paper, the matrix of gasoline direct injection passenger cars is applied to analyze the real-world emissions. The results show that high acceleration and high speed conditions are major conditions for the particulate number emissions, and the particulate number emissions are positively correlated with torque and throttle opening. The catalyst temperature and saturation are important factors that affect nitrogen oxide emission. The nitrogen oxide emissions of low speed and low torque conditions cannot be ignored in real-world driving. The carbon dioxide emissions are positively correlated with acceleration, torque and throttle opening. Once the vehicles are in the acceleration condition, the carbon dioxide emissions increase rapidly. The vehicles with higher average emission factors are more susceptible to driving behaviors, and the differences in the emission factors ar... [more]

The objective of this work was to present an overview of abrasive technologies with solid carbon dioxide as a blasting medium. These methods can be successfully used for the removal of a wide range of types of industrial pollution. The article covers literature reports in the field of the examined cleaning mechanisms and manufacturing process of dry ice, focusing on the structure and size of the product. Having the correct understanding of these processes is crucial for further technological development. Then various configurations of the dry-ice-blasting and snow-blasting systems are presented, including a range of typical parameters met in the literature and in industrial applications. Because the nozzle can be treated as a key part of the system, typical examples of nozzles are described. Special attention is paid to the usability of each type. This study also covers the actual scope of applications for the described systems, especially in industry and science.

A factor influencing the effectiveness of CO2 injection is miscibility. Besides the miscible injection, CO2 may also contribute to oil recovery improvement by immiscible injection through modifying several properties such as oil swelling, viscosity reduction, and the lowering of interfacial tension (IFT). Moreover, CO2 immiscible injection performance is also expected to be improved by adding some solvent. However, there are a lack of studies identifying the roles of solvent in assisting CO2 injection through observing those properties simultaneously. This paper explains the effects of CO2−carbonyl and CO2−hydroxyl compounds mixture injection on those properties, and also the minimum miscibility pressure (MMP) experimentally by using VIPS (refers to viscosity, interfacial tension, pressure−volume, and swelling) apparatus, which has a capability of measuring those properties simultaneously within a closed system. Higher swelling factor, lower viscosity, IFT and MMP are observed from a C... [more]

This is supplemental data for a paper submitted to the PSE 2021+ conference. It includes values used to calculate emissions reductions and financial value of biomass pyrolysis by-product utilization.

As part of efforts to reduce carbon emissions in the iron and steel industry, which are especially pertinent in Canada due to rising carbon taxes, Canadian producers have been investigating the effects of replacing coal used in pulverized coal injection with biochar. Although there has been research into the economic value and effect on net life cycle emissions of using the biochar product itself, there are no comprehensive techno-economic analyses which investigate the value and potential uses of the by-products of biomass pyrolysis. These by-products include volatile organic compounds, known collectively as tar or bio-oil, and light gases, which are mainly hydrogen, carbon monoxide, carbon dioxide, and methane. Since only 20-30% of the mass of pyrolyzed biomass is actually converted to char, with the rest converted to the by-products, [1] usage of these by-products is likely the key to increasing the value of biochar to a degree that makes up for the market price of biochar currently... [more]

Chemical industries rely heavily on fossil resources for the production of carbon-based chemicals. A possible transformation towards sustainability is the usage of carbon dioxide as a source of carbon. Carbon dioxide is activated for follow-up reactions by its conversion to carbon monoxide. This can be accomplished by electrochemical reduction in solid oxide cells. In this work, we investigate the process performance of the direct high-temperature CO2 electrolysis by current-voltage characteristics (iV) and Electrochemical Impedance Spectroscopy (EIS) experiments. Variations of the operation parameters temperature, load, fuel utilization, feed gas ratio and flow rate show the versatility of the procedure with maintaining high current densities of 0.75 up to 1.5 A·cm−2, therefore resulting in high conversion rates. The potential of the high-temperature carbon dioxide electrolysis as a suitable enabler for the activation of CO2 as a chemical feedstock is therefore appointed and shown.

Carbon dioxide is the most influential gas in greenhouse gasses and its amount in the atmosphere reached 412 µmol/mol in August 2020, which increased rapidly, by 48%, from preindustrial levels. A brand-new chemical industry, namely organic chemistry and catalysis science, must be developed with carbon dioxide (CO2) as the source of carbon. Nowadays, many techniques are available for controlling and removing carbon dioxide in different chemical processes. Since the utilization of CO2 as feedstock for a chemical commodity is of relevance today, this study will focus on how to increase CO2 solubility in culture media used for growing microbes. In this work, the CO2 solubility in a different medium was investigated. Sodium hydroxide (NaOH) and monoethanolamine (MEA) were added to the culture media (3.0 g/L dipotassium phosphate (K2HPO4), 0.2 g/L magnesium chloride (MgCl2), 0.2 g/L calcium chloride (CaCl2), and 1.0 g/L sodium chloride (NaCl)) for growing microbes in order to observe the dif... [more]

Solubility data is one of the essential basic data for CO2 capture by ionic liquids. A selective ensemble modeling method, proposed to overcome the shortcomings of current methods, was developed and applied to the prediction of the solubility of CO2 in imidazolium ionic liquids. Firstly, multiple different sub−models were established based on the diversities of data, structural, and parameter design philosophy. Secondly, the fuzzy C−means algorithm was used to cluster the sub−models, and the collinearity detection method was adopted to eliminate the sub−models with high collinearity. Finally, the information entropy method integrated the sub−models into the selective ensemble model. The validation of the CO2 solubility predictions against experimental data showed that the proposed ensemble model had better performance than its previous alternative, because more effective information was extracted from different angles, and the diversity and accuracy among the sub−models were fully inte... [more]

A comprehensive energy and exergoeconomic analysis of a novel transcritical refrigeration cycle (NTRC) is presented. A second ejector is introduced into the conventional refrigeration system for the utilization of the gas-cooler waste heat. The thermodynamic properties of the working fluid are estimated by the database of REFPROP 9, and a FORTRAN program is used to solve the system governing equations. Exergy, energy, and exergoeconomic analyses of the two cycles are carried out to predict the exergetic destruction rate and efficiency of the systems. The optimum gas cooler working pressure will be determined for both cycles. A comprehensive comparison is made between the obtained results of the conventional and the new cycles. An enhancement of approximately 30% in the coefficient of performance (COP) of the new cycle was found in comparison to the value of the conventional cycle. In addition, the results of the analysis indicated a reduction in the overall exergy destruction rate and... [more]

A novel process of membrane separation for H2/CO2 of shifted syngas coupled with gasoil hydrogenation (NMGH) is proposed. First, a new process, with two-stage CO2-selective and one-stage H2-selective membranes, was developed to substitute the conventional PSA separation devices to remove CO2 and purify H2 in coal gasification refineries to reduce energy consumption and investment costs. Then, the process was coupled with gasoil hydrogenation and the recycled H2 produced by the hydrogenation reactor could be further purified by the H2-selective membrane, which increased the H2 concentration of the hydrogenation reactor inlet by about 11 mol.% compared with the conventional direct recycling process, and the total system pressure was reduced by about 2470 kPa. At the same time, this additional membrane separation and purification prevented the accumulation of CO/CO2 in the recycled H2, which ensured the activity of the catalyst in the reactor and the long-term stable operation of the devi... [more]

In mammalian cell culture, especially in pharmaceutical manufacturing, pH is a critical process parameter that has to be controlled as accurately as possible. Not only does pH directly affect cell culture performance, ensuring a comparable pH is also crucial for scaling and transfer of processes. A sample-based offline pH measurement is commonly used to ensure correct bioreactor pH probe signals after sterilization and as a detection measure for drifts of probe signals. However, the sample-based pH offline measurement does not necessarily deliver required accuracy. Offsets between bioreactor pH and sample pH heavily depend on equipment, local procedures and the offline measurement method that is used. This article adequately describes a novel, non-invasive method to determine pH and pCO2 in sterile bioreactors without the need to sample and measure offline. This method utilizes the chemical correlation between carbon dioxide in the gas phase, dissolved carbon dioxide, bicarbonate and d... [more]

The increasing trends in gas emissions have had direct adverse impacts on human health and ecological habitats in the world. A variety of technologies have been deployed to mitigate the release of such gases, including CO2, CO, SO2, H2S, NOx and H2. This special issue on gas-capture processes collects 25 review and research papers on the applications of novel techniques, processes, and theories in gas capture and removal.