Dry CO2 Research Articles

Enhanced carbon dioxide adsorption by amine-modified KCC-1

The increase of carbon dioxide (CO2) emission due to anthropogenic activities has become a threat to our environment. Hence there is an urgent need to control its emission via carbon capture and storage (CCS) strategy. However, the readily available method, which is liquid amine absorption, possesses some drawbacks including being energy intensive and may cause material corrosion. Dry CO2 adsorption using amine-functionalized silica has been studied to provide a simple and cost-effective alternative for CO2 capture. Recently emerged dendritic fibrous silica possesses excellent morphology and characteristics to be developed as an effective CO2 adsorbent. Herein, the CO2 adsorption performance using amine-modified fibrous silica nanoparticle, KCC-1 was studied. As-synthesized KCC-1 was modified with tetraethylenepentamine (TEPA) via impregnation method. Its characteristics were studied before it was subjected to the CO2 adsorption experiment. The Fourier Transform Infra-red (FTIR) results indicates that TEPA was successfully impregnated with peaks at 3383 cm−1, 2935 cm−1, 2837 cm−1, 1558 cm−1, 1479 cm−1 and 1309 cm−1, while X-ray diffraction (XRD) analysis showed that KCC-1 structure was preserved. KCC-1/TEPA recorded higher adsorption capacity of CO2 compared to the unmodified KCC-1, with maximum adsorption capacity of 189.86 mg/g. Equilibrium isotherm model fitting of the CO2 adsorption was also carried out, and the adsorption data of KCC-1/TEPA fitted well to Toth isotherm. Overall, it has been demonstrated that KCC-1/TEPA has excellent potential to be used for CO2 adsorption, and more studies need to be conducted for its development.

Lethality of high-pressure carbon dioxide on Shiga toxin-producing Escherichia coli, Salmonella and surrogate organisms on beef jerky

Low water activity (aW) foods permit the survival of low-infectious dose pathogens including Escherichia coli and Salmonella. Desiccation of non-heat resistant E. coli and Salmonella enterica increases their heat resistance; therefore, alternative methods are necessary to ensure the safety of low aW foods. High-pressure carbon dioxide (HPCD) reduced microbial contaminants in high aW foods. This study aimed to identify HPCD conditions that reduce pathogenic E. coli and Salmonella in low aW conditions. Four strains of Shiga toxin-producing E. coli (STEC) and one strain of enteropathogenic E. coli were treated as a cocktail, and five strains of Salmonella were treated individually. The suitability of E. coli AW1.7, Pediococcus acidilactici FUA 3072, Enterococcus faecium NRRL B-2354 and Staphylococcus carnosus R6 FUA 2133 as surrogate organisms was evaluated. Treatments were validated in beef jerky. Samples were equilibrated to aW 0.75 and treated with heat, HPCD or pressurized N2. Treatment of desiccated E. coli AW1.7 and the STEC cocktail with dry gaseous CO2 (5.7 MPa and 65 °C) did not reduce cell counts; however, treatment with gaseous CO2 saturated with water reduced cell counts of all strains of E. coli. Treatment of beef jerky inoculated with E. coli and Salmonella with saturated gaseous CO2 resulted in >5-log reductions for all strains. E. faecium NRRL B-2354 and S. carnosus R6 were suitable surrogates for Salmonella on beef jerky treated with HPCD. Treatment of beef jerky with water-saturated gaseous CO2 was more effective than treatment with supercritical CO2 or treatments with N2 at the same temperature and pressure. Overall, the treatment of low aW foods with water-saturated gaseous HPCD can meet industry standards by achieving a >5-log reductions of E. coli and Salmonella. Additionally, surrogate organisms representing pathogenic E. coli and Salmonella have been validated.

Understanding How Ligand Functionalization Influences CO2 and N2 Adsorption in a Sodalite Metal-Organic Framework.

In this work, a detailed study is conducted to understand how ligand substitution influences the CO2 and N2 adsorption properties of two highly crystalline sodalite metal-organic frameworks (MOFs) known as Cu-BTT (BTT-3 = 1,3,5-benzenetristetrazolate) and Cu-BTTri (BTTri-3 = 1,3,5-benzenetristriazolate). The enthalpy of adsorption and observed adsorption capacities at a given pressure are significantly lower for Cu-BTTri compared to its tetrazole counterpart, Cu-BTT. In situ X-ray and neutron diffraction, which allow visualization of the CO2 and N2 binding sites on the internal surface of Cu-BTTri, provide insights into understanding the subtle differences. As expected, slightly elongated distances between the open Cu2+ sites and surface-bound CO2 in Cu-BTTri can be explained by the fact that the triazolate ligand is a better electron donor than the tetrazolate. The more pronounced Jahn-Teller effect in Cu-BTTri leads to weaker guest binding. The results of the aforementioned structural analysis were complemented by the prediction of the binding energies at each CO2 and N2 adsorption site by density functional theory calculations. In addition, variable temperature in situ diffraction measurements shed light on the fine structural changes of the framework and CO2 occupancies at different adsorption sites as a function of temperature. Finally, simulated breakthrough curves obtained for both sodalite MOFs demonstrate the materials' potential performance in dry postcombustion CO2 capture. The simulation, which considers both framework uptake capacity and selectivity, predicts better separation performance for Cu-BTT. The information obtained in this work highlights how ligand substitution can influence adsorption properties and hence provides further insights into the material optimization for important separations.

Versatile application of wet-oxidation for ambient CO abatement over Fe(OH)x supported subnanometer platinum group metal catalysts

The efficient and stable abatement of CO pollutant under ambient conditions is of great significance; however, it remains a formidable challenge. Herein, we report the versatile application of wet oxidation over Fe(OH) x supported subnanometer Pt group metal (PGM) catalysts for the complete removal of CO under ambient temperature and humidity conditions. Typically, the 1.8 wt% Rh/Fe(OH) x catalyst exhibited better durability during a ∼1400 min run for wet oxidation than for dry CO oxidation. Multiple characterization results including HR-TEM, H 2 -TPR, and in-situ DRIFTS suggested that Fe(OH) x , with good reducibility, promoted by the subnanometer Rh clusters, provided sites for the adsorption and reaction of O 2 and H 2 O to form OH species. Subsequently, these OH species reacted with the adsorbed CO on Rh sites with a considerably lower activation energy (9 kJ mol −1 ) than that of dissociated O species (22 kJ mol −1 ), thus rationalizing the outstanding performance of Rh/Fe(OH) x for wet oxidation. Extended experiments with other PGMs revealed a good generality for the application of wet oxidation in the efficient abatement of CO under humid conditions with Fe(OH) x as the support. Versatile CO abatement under ambient conditions is achieved by wet-oxidation over Fe(OH) x supported subnanometer Pt group metal catalysts owing to the facile formation and reaction of hydroxyl groups.

Comparative analysis of dry, flood, MQL and cryogenic CO2 techniques during the machining of 15-5-PH SS alloy

The Precipitation Hardening (PH) Stainless Steel (SS) is considered as a promising alternative for aerospace and marine sectors owing to its good mechanical properties with high corrosion resistance. But the lower thermal conductivity and the presence of precipitates lower its machinability in terms of rapid tool wear. In this context, this study aims to analyze the dry, flood, MQL (Minimum Quantity Lubrication), and cryogenic machining with LCO2 in terms of tool wear for the turning tests of 15-5 PH SS. Apart from progressive flank wear, the machining performance of different cutting fluid strategies is compared by analyzing the crater wear, progressive power consumption, and surface roughness, microhardness, and microstructure of machined surface and chip. The performance of sustainable cryogenic machining is found superior in terms of lower tool wear, power consumption, subsurface microhardness. The relatively finer grain size and helical chip with smaller diameter are produced in the cryogenic machining while the better surface finish is observed for the flood machining in contrast to other cutting fluid strategies.

Creating nanocrystallized chemotherapy: the differences in pressurized aerosol chemotherapy (PAC) via intracavitary (IAG) and extracavitary aerosol generation (EAG) regarding particle generation, morphology and structure.

Background: Nanocrystallization is a promising field for the development of new drugs. This study aims to present the use of nanocrystallization via intraperitoneal nanoaerosol therapy (INAT) for the treatment of peritoneal metastases.Methods: A continuous aerosol generation device was used to aerosolize a highly concentrated doxorubicin solution within a dry CO2 environment. The produced nanoaerosol was directed into an ex vivo abdominal model and collision of aerosol particles with placed samples was subject to further analysis via scanning-electron microscopy (SEM). SEM detected structural changes of particles caused by migration to different locations.Results: It was possible to visualize the contact of doxorubicin aerosol particles with the surface. Larger particles as well as particles closer to the aerosol generation chamber collided with the glass sample creating liquid drops, while smaller particles with more distance to the aerosol chamber collided as highly concentrated nanocrystals. The amount of nanocrystal particles outweighed the amount of fluid aerosol particles by far.Conclusions: Under optimal conditions, the formation of nanocrystals via aerosol creation device is possible. While a wide range of possible applications of nanocrystals is conceivable, surface coating with drug particles is especially interesting as it may serve as an alternative to conventional liquid intraperitoneal chemotherapy. Further studies are required to investigate nanocrystallization of chemotherapeutic solutions as well as its physical and pharmacological properties and side effects.

CO2 Absorption from Gas Turbine Flue Gas by Aqueous Piperazine with Intercooling

Amine scrubbing is the most mature technology for postcombustion carbon capture. Much bench- and pilot-scale work has been focused on CO2 capture from coal-fired flue gas. Because natural gas is inexpensive and readily available in the United States and other countries, the natural gas combined-cycle (NGCC) has been replacing coal for electricity generation. Carbon capture for NGCC is therefore an important technology for the modern power plants. The Piperazine (PZ) Advanced Stripper (PZAS) technology has been established as a benchmark system for second-generation amine scrubbing for CO2 capture from coal-fired flue gas. It has a fast absorption rate, good energy performance, and strong resistance to thermal degradation and oxidation. PZAS was operated with simulated NGCC flue gas (4.3 mol % (dry) CO2) at the National Carbon Capture Center (NCCC) in Wilsonville, Alabama in 2019. This paper presents the absorber performance and model validation for the campaign. The absorber was tested with in-and-out and with pump-around intercooling. The variable operating conditions included lean loading (0.19–0.25 m CO2/mol alkalinity), gas temperature (40, 78 °C), and intercooling temperature (35, 40 °C). Using 5 m PZ CO2 removal from 82% to 96% was achieved with intercooling and only 12 m of packing. A rigorous, rate-based absorber model accurately predicted the CO2 removal and temperature profile. The model shows that the delta loading of the solvent at NGCC conditions for 90% removal is greater than at coal conditions, but high CO2 removal (99%) is more difficult to achieve with NGCC gas than with coal-fired flue gas. The pump-around intercooling was effective, and the intercooling temperature had a large impact on the absorber performance. With pump-around, the delta loading penalty for hot gas feed into absorber without a direct contact cooler was less than 5%.

Experimental and numerical investigation of wormholing during CO2 storage and water alternating gas injection

Carbon dioxide (CO2) injection into geological formations is gaining global interest. Examples include CO2 storage to mitigate greenhouse gas emissions and water alternating gas (WAG) injection for enhanced oil recovery (EOR) and storage. Injected CO2 inevitably dissolves in water (injected or formation), which results in acidic conditions that can dissolve the rock matrix in carbonate reservoirs. Depending on the dissolution’s location and pattern in the reservoir, this may benefit well injectivity and/or threaten well integrity. Fine-gridded models with detailed physics and chemistry capture the relevant effects but are not suitable for the application to the field scale where instead correlations are used. The correlations that exist, however, are so far not sufficiently constrained to be of practical use. We report new experimental and modelling work that provides the means for qualitative to quantitative field-scale predictions of these effects for all the different combinations of CO2–water injection of interest. These show that, for conventional injection strategies (dry CO2 injection and WAG), there are no material concerns, but there are potential well integrity issues that need more detailed investigation for the proposed alternative strategies of carbonated water injection or co-injection.

Monomodal Ultrahigh-Molar-Mass Polycarbonate Homopolymers and Diblock Copolymers by Anionic Copolymerization of Epoxides with CO2

Whatever the chemistry used for the synthesis of aliphatic polycarbonates, in particular, those of high molar mass, the adventitious presence of water leads to bimodal GPC traces and affords polycarbonate samples of uncontrolled and unpredictable molar masses. It appears that among all reagents used in the copolymerization of CO2 and epoxides, CO2 is the most difficult one to dry. To address this issue, triisobutylaluminum (TiBA) was employed in this work to dry CO2 through a bubbling method; its drying capability was investigated in the context of the copolymerization of CO2 with epoxides initiated by onium chloride in the presence of triethylborane (TEB). It was then compared to the efficiency of other already reported drying agents such as phosphorus pentoxide, molecular sieves and commercially available CO2 purifiers. With TiBA-dried CO2, its copolymerizations respectively with propylene oxide (PO) and cyclohexene oxide (CHO) could be successfully achieved in a wide range of degrees of polymerization (DP), with the value of DP as high as 16000. Diblock copolymers poly(propylene carbonate-b-cyclohexene carbonate) (PPC-b-PCHC) could also be prepared through sequential addition of epoxide monomers. The polycarbonates obtained under the conditions were all well-defined as characterized by NMR, GPC, triple detector-GPC, and differential scanning calorimetry (DSC).

Pore-Scale Experimental Investigation of the Effect of Supercritical CO2 Injection Rate and Surface Wettability on Salt Precipitation

Injectivity is one of the most important factors to evaluate the feasibility of CO2 geological storage. Salt precipitation due to the mass of dry CO2 injected into a saline reservoir may cause a significant decrease in injectivity. However, the coupling effect of injection parameters and reservoir conditions on salt precipitation is not clear. Here, we conducted pore-scale visualization experiments to study the morphology and distribution of salt precipitation in porous structures and their effects on permeability reduction. The experimental results are achieved by controlling the supercritical CO2 injection rate and the surface wettability at the reservoir temperature and pressure. It is found that for hydrophilic and neutral porous surfaces, ex situ precipitation occurs and blocks the entirety of pore throats and bodies, which results in a significant reduction in permeability. Increasing the CO2 injection rate can suppress the capillary reflow and prevent the permeability reduction. For a hydrophobic porous surface, in situ precipitation occurs and occupies much smaller pore volume, which has a slight effect on permeability reduction compared to the hydrophilic samples at the same injection rate. Increasing the CO2 injection rate and dewetting the injection well and formation nearby reduce the possibility of salt accumulation, which has less effect on CO2 injectivity.

Co-free La0.6Sr0.4Fe0.9Nb0.1O3-δ symmetric electrode for hydrogen and carbon monoxide solid oxide fuel cell

Co-free La0.6Sr0.4FeO3-δ (LSFNb0) and La0.6Sr0.4Fe0.9Nb0.1O3-δ (LSFNb0.1) perovskite oxides were prepared by a standard solid-state reaction method. The structural stability and electrochemical performance of La0.6Sr0.4Fe0.9Nb0.1O3-δ as both cathode and anode were studied. Nb dopant in LSFNb0 significantly enhances the structural and chemical stability in anode condition. At 800 °C, the polarization resistances (Rp) of LSFNb0.1 symmetric electrode based on YSZ electrolyte are 0.5 and 0.05 Ω cm2 in H2 and air, respectively. The peak power densities of LSFNb0.1 based on LSGM electrolyte-supported SSOFCs are 934 and 707 mW cm−2 at 850 °C in H2 (3% H2O) and dry CO, respectively. Moreover, the symmetric cell exhibits reasonable stability in both H2 and CO fuel, suggesting that La0.6Sr0.4Fe0.9Nb0.1O3-δ may be a potential symmetric electrode material for hydrogen and carbon monoxide SOFCs.

Seasonal changes in soil respiration linked to soil moisture and phosphorus availability along a tropical rainfall gradient

Humid tropical forests contain some of the largest soil carbon (C) stocks on Earth, yet there is uncertainty about how carbon dioxide (CO2) fluxes will respond to climate change in this biome. The magnitude of change in soil respiration over seasonal wetting and drying cycles can provide insight to how CO2 fluxes might respond to precipitation changes. We measured soil respiration in 15 distinct forests across rainfall and soil fertility gradients in lowland Panama to assess spatial variation in seasonal patterns. We predicted that seasonal changes in soil respiration would be related to soil moisture, and that the ratio of wet to dry season CO2 fluxes across landscape gradients would be regulated by soil organic C and nutrient availability. We found that soil respiration during the dry season was relatively stable across the rainfall gradient, averaging 4.3 ± 0.3 µmol CO2 m−2 s−1. In contrast, wet season respiration varied markedly, ranging among sites from a decline of 19% to an increase of 360% in comparison to dry season values. Soil moisture, air temperature, and rainfall were the best predictors of instantaneous soil respiration (R2 = 0.18). Meanwhile, ratios of wet to dry season CO2 fluxes were best predicted by site-scale resin-extractable phosphorus (P; R2 = 0.48). That is, soil respiration in P-rich sites increased more during the wet season relative to respiration in P-poor sites. Also, sites with Wet:Dry season CO2 flux ratios < 1 were all poor in soil P, defined as resin P concentrations < 2 mg P kg−1. Although soil organic C was not related to instantaneous soil respiration rates, forest floor biomass accumulation during the dry season was positively correlated with soil respiration during the wet season (R2 = 0.26), indicating the contribution of microbial decomposition to wet season soil respiration. Overall, nutrient availability regulated soil respiration responses to increased moisture during the wet season, while low soil moisture uniformly suppressed soil respiration across sites during the dry season. Phosphorus availability might therefore regulate feedbacks to climate change among humid tropical forests.

Mesocellular silica foam supported polyamine adsorbents for dry CO2 scrubbing: Performance of single versus blended polyamines for impregnation

Siliceous foams with three-dimensional mesoporous structures were synthesised and used to prepare polyethyleneimine (PEI) and tetraethylenepentamine (TEPA)-functionalised sorbent materials for CO2 capture, with a particular focus on the performance of impregnated amine blends versus single amine sorbent systems. Using thermal gravimetric analysis supported by other characterisations, the obtained results demonstrated that compared to the impregnated mono-component PEI and TEPA sorbent systems, the binary PEI-TEPA blend sorbents all achieved significantly higher CO2 capacities and faster adsorption kinetics, due to the enhanced formation of micro-cavities within the supported amine layers that led to reduced CO2 diffusion resistance and increased accessibility of the amines to CO2. It was found that at 70 °C and 15% CO2 in N2, the CO2 adsorption capacity of the silica-supported PEI–TEPA (3:2) at 70 wt% amine loading increased by 40% compared to the supported PEI at the same level of amine impregnation, whilst the time to achieve 80% and 90% of the equilibrium adsorption capacity was reduced by 70% and 35%, respectively. Extended cyclic adsorption-desorption tests showed that the TEPA-blended PEI sorbents all exhibited considerably higher thermal stability than both the supported PEI and TEPA sorbents, being indicative of the suppressed urea formation even in the pure and dry CO2 gas stream used in the desorption cycles. Calculations indicated that compared to the silica-supported PEI sorbents, the higher adsorption capacities achieved by the binary PEI-TEPA sorbent systems could lead up to 10% reduction in the energy requirement for sorbent regeneration, highlighting the suitability of using amine blending as a facile effective strategy to promote the overall performance of polyamine-based adsorbents for CO2 separation.

Convection heat transfer and friction characteristics of liquid CO2-N2 foam fracturing fluid using C4F9OCH3 as frother

The liquid CO2–N2 foam fracturing fluid containing C4F9OCH3 causes no damage to formation, similar to dry CO2 fracturing, can be used to stimulate water sensitivity and low-permeability gas reservoirs. The main objective of this experimental study was to ascertain the convective heat transfer and frictional characteristics of this modified dry fracturing fluid system. A foam fracturing fluid test system was adopted in this study. The results showed that the viscosity of the liquid CO2–N2 foam fracturing fluid with C4F9OCH3 added was significantly higher compared with the liquid CO2–N2. The optimum frother concentration was 0.65%. The shear rate had the most significant effect on the convective heat transfer. The pressure had a significant effect on the frictional characteristics of the complex foam fluid due to the compressibility of the internal and external phases. When the flow velocity was greater than 1.4 m/s, the frictional resistance coefficients for foams of different qualities were similar. The velocities in the expression of the generalized Reynolds number, Re′, and the generalized Prandtl number, Pr′, were not sufficient to describe the influence of the shear rate on the heat transfer. When fitting the convection heat transfer coefficient, the effect of shear rate on coefficient of thermal conductivity was also considered. These results can be used to calculate the temperature field and predict the friction pressure drop in the use of this foam fracturing fluid.

New estimate of particulate emissions from Indonesian peat fires in 2015

Abstract. Indonesia contains large areas of peatland that have been drained and cleared of natural vegetation, making them susceptible to burning. Peat fires emit considerable amounts of carbon dioxide, particulate matter (PM) and other trace gases, contributing to climate change and causing regional air pollution. However, emissions from peat fires are uncertain, due to uncertainties in emission factors and fuel consumption. We used the Weather Research and Forecasting model with chemistry and measurements of PM concentrations to constrain PM emissions from Indonesian fires during 2015, one of the largest fire seasons in recent decades. We estimate primary PM2.5 (particles with diameters less than 2.5 µm) emissions from fires across Sumatra and Borneo during September–October 2015 were 7.33 Tg, a factor 3.5 greater than those in the Fire Inventory from NCAR (FINNv1.5), which does not include peat burning. We estimate similar dry fuel consumption and CO2 emissions to those in the Global Fire Emissions Database (GFED4s, including small fires) but PM2.5 emissions that are a factor of 1.8 greater, due to updated PM2.5 emission factors for Indonesian peat. Fires were responsible for an additional 3.12 Tg of secondary organic aerosol formation. Through comparing simulated and measured PM concentrations, our work provides independent support of these updated emission factors. We estimate peat burning contributed 71 % of total primary PM2.5 emissions from fires in Indonesia during September–October 2015. We show that using satellite-retrieved soil moisture to modify the assumed depth of peat burn improves the simulation of PM, increasing the correlation between simulated and observed PM from 0.48 to 0.56. Overall, our work suggests that peat fires in Indonesia produce substantially greater PM emissions than estimated in current emission inventories, with implications for the predicted air quality impacts of peat burning.

Understanding indoor environmental conditions and occupant’s responses in houses of older people

In Australia, the vast majority of older people, those aged 65 years and over, want to live at their own homes for as long as possible. Older people are, however, vulnerable to extreme conditions, hot or cold, and therefore it is crucial to ensure that the home’s indoor environmental conditions are conducive to their health and well-being. The first step to do this is by understanding the existing conditions in homes of older people so that appropriate steps for improvements can be taken. This paper presents an on-going study to understand the indoor environmental conditions and occupant’s responses in homes of older people in South Australia. The study is conducted using a robust indoor environmental monitoring system that is integrated with a user-friendly occupant survey system using an electronic tablet, allowing the occupants to reflect on their “right here right now” experience over different seasons in a year. The paper discusses the development of this integrated system and reports some preliminary data. Preliminary results showing the associations between measured environmental data, such as dry bulb temperature, radiant temperature, air velocity, and CO2 level, and thermal sensation, comfort, perception of indoor quality and self-reported health/well-being will also be presented.

Prevention of Intraoperative Hypothermia in Laparoscopy by the Use of Body-Temperature and Humidified CO2: a Pilot Study

Introduction Hypothermia is defined as a decrease in body core temperature to below 36 °C. If intraoperative heat-preserving measures are omitted, a patientʼs temperature will fall by 1 – 2 °C. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality. The temperature of the insufflation gas is usually disregarded in the treatment and prevention of hypothermia. This study was conducted to investigate the effect of body-temperature and humidified CO 2 on the intraoperative temperature profile and avoidance of hypothermia in laparoscopic surgery. Material and Methods In this retrospective, non-randomised case control study, 110 patients whose planned operation lasted at least 60 minutes were identified from 376 patients by means of an algorithm. Dry (20% humidity) CO 2 at room temperature was insufflated in 51 patients (control group). 59 patients were insufflated with humidified (98% humidity) CO 2 at body temperature (37 °C) (study group). These conditions were achieved with the HumiGard MR860 Surgical Humidification System (Fisher & Paykel Healthcare Limited, Auckland, New Zealand). The intraoperative temperature profile was evaluated by measurements every 10 minutes. Statistical analysis was performed with IBM ® SPSS ® Statistics 23.0.0. Results The intraoperative temperature in the control group fell steadily, while a continuous rise in temperature was observed in the study group. Warming was demonstrated in the study group with a start-end temperature difference of 0.09 °C, which differed significantly from the control group, in which it was − 0.09 °C (p = 0.011). The middle-end difference of 0.11 °C showed even higher significance in favour of the warmed gas (p = 0.003). The rate of hypothermia at the start of the operation fell from 50 to 36% in the study group and increased from 36 to 42% in the control group. Conclusion These results show that the use of body-temperature and humidified insufflation gas for laparoscopy can help to prevent intraoperative hypothermia.

Polyethyleneimine-crosslinked cellulose aerogel for combustion CO2 capture

Polyethylenimine (PEI) will block the channel of pore when it was impregnated in the porous solid, limiting its practical application in CO2 adsorption. In this method, a novel polyethyleneimine-crosslinked cellulose (PCC) aerogel sorbent was prepared by the sol-gel process, hydrolysis reaction and crosslinking reaction. The specific surface area of porous PCC aerogel was still retained 234.2 m2/g when the content of nitrogen was 17.4 wt%. The CO2 adsorption capacity of PCC aerogel reached 2.31 mmol/g at 25 ℃ under pure dry CO2 atmosphere. Pseudo-second order model perfectly is suitable to predict the CO2 adsorption behaviors of PCC aerogel at different temperatures. The CO2 diffusion mechanism of PCC aerogel was limited by not only intra-particle diffusion but also surface diffusion. The PCC aerogel showed excellent CO2 adsorption-desorption recyclability after 10 cycles. This work proved that the PCC aerogel played an important role as a potential CO2 adsorption solids.

Cobalt–free La0.5Sr0.5Fe0.9Mo0.1O3–δ electrode for symmetrical SOFC running on H2 and CO fuels

Cobalt–free perovskite La0.5Sr0.5Fe0.9Mo0.1O3–δ (LSFMo) was evaluated as the electrode of symmetrical SOFC (S–SOFC) using H2 and CO as fuels. XRD results demonstrate that the LSFMo electrode is redox stable at a temperature below 800 °C. Furthermore, the chemical compatibility of LSFMo electrode with both Sm0.2Ce0.8O1.95 (SDC) and La0.9Sr0.1Ga0.8Mg0.2O3–δ (LSGM) electrolytes was assessed. The thermal expansion coefficients (TECs) of the LSFMo at 30–850 °C are 13.4 × 10−6 K−1 in air and 15.1 × 10−6 K−1 in 5% H2/Ar. However, for the pre–reduced LSFMo, the TEC in 5% H2/Ar decreases to 11.8 × 10−6 K−1. Using LSFMo as symmetrical electrode of S–SOFCs, the maximum power densities (Pmax) of 562 mW cm−2 in dry H2 and 474 mW cm−2 in dry CO at 750 °C are attained based on 300 μm thick SDC electrolyte, while based on the LSGM electrolyte with same thickness, the Pmax attain 508 mW cm−2 in dry H2 and 379 mW cm−2 in dry CO. For the LSGM supported S–SOFC, the total polarization resistances (Rp) attain 0.460 Ω cm2 in dry H2 and 1.099 Ω cm2 in dry CO at 750 °C. Additionally, the S–SOFCs with LSFMo electrode exhibit good power cycling stability, long–term stability and multiple redox and thermal cycling stability. Above results indicate that the LSFMo material is a very potential symmetrical electrode for S–SOFCs.

Electrical Detection of Creeping Discharges over Insulator Surfaces in Atmospheric Gases under AC Voltage Application

Creeping discharges over insulator surfaces have been related to the presence of triple junctions in compressed gas insulated systems. The performance of dielectric materials frequently utilised in gaseous insulating high voltage applications, stressed under triple junction conditions, has been an interesting topic approached through many different physical perspectives. Presented research outcomes have contributed to the understanding of the mechanisms behind the related phenomena, macroscopically and microscopically. This paper deals with the electrical detection of creeping discharges over disc-shaped insulator samples of different dielectric materials (polytetrafluoroethylene (PTFE), epoxy resin and silicone rubber) using atmospheric gases (dry air, N2 and CO2) as insulation medium in a point-plane electrode arrangement and under AC voltage application. The entire approach implementation is described in detail, from the initial numerical field simulations of the electrode configuration to the sensing and recording devices specifications and applications. The obtained results demonstrate the dependence of the generated discharge activity on the geometrical and material properties of the dielectric and the solid/atmospheric gas interface. The current work will be further extended as part of a future extensive research programme.