Low CO2 Concentrations Research Articles

КОРРЕКЦИЯ КИСЛОРОДНОГО ГОЛОДАНИЯ В ЭКСПЕРИМЕНТАХ НА ЖИВОТНЫХ ПРИ МОДЕЛИРОВАНИИ ЭФФЕКТОВ, ВЫЗЫВАЕМЫХ ОСТРОЙ ДЫХАТЕЛЬНОЙ НЕДОСТАТОЧНОСТЬЮ, С ПОМОЩЬЮ МНОГОКОМПОНЕНТНОЙ ГАЗОВОЙ СМЕСИ НА ОСНОВЕ КОМБИНАЦИИ ИНЕРТНЫХ ГАЗОВ

Acute respiratory insufficiency (ARI) accompanied with hypoxemia and hypercapnia requires oxygen therapy. The helium-oxygen therapy secures from the undesirable effects of oxygen therapy. Earlier we showed that introduction of argon in a breathing mixture (BM) reduces the effect of hypoxia. Purpose of the work is to test the potentiality of BM containing a combination of inert gases to counteract oxygen starvation in acute ARI-provoking experiments with animals. Fourteen Wistar rats with a body mass of 276 ± 14.6 grams were divided into two groups. An integral noninvasive technology was used for real-time assessment of oxygen transport and consumption in each animal. Both the experiment and control animals breathed a mixture with a low O2 and high CO2 concentration. The control animals received a routine therapy by a hyperoxic mixture containing nitrogen and carbon dioxide. The experimental animals were treated with a hyperoxic mixture containing helium and argon, and carbon dioxide to induce hypercapnia. The results demonstrated reliably that the hyperoxic heluim-argon mixture reduces burden on the external respiration and favors oxygen utilization in tissues; however, this happens at the expense of a greater stress to the cardiovascular system. In contrast, the hyperoxic mixture used in the control stressed the external respiration rather than the cardiac muscle.

Flue gas CO2 supply methods for microalgae utilization: A review

The potential for utilizing flue gas as a carbon source in microalgal cultivation holds great promise. Incorporating flue gas as a carbon source into microalgae culture processes can accelerate the growth rate of microalgae, consequently enhancing the overall economic viability of the integrated process. There are two key sources of flue gas to consider: flue gas from coal-fired power plants, characterized by a CO2 concentration of 12–15 w/w%, and flue gas from coal chemical processes, boasting a CO2 concentration of 90–99 w/w%. Additionally, the choice between an open or sealed microalgae culture system can also influence economic efficiency. Thus, there are four distinct microalgal cultivation routes to assess: in-situ open systems, off-situ open systems, in-situ sealed systems, and off-situ sealed systems. The incorporation of flue gas as a carbon source in microalgae cultivation demonstrates significant potential for reducing both environmental impact and costs, rendering it a highly promising and sustainable approach for economically efficient microalgae cultivation. In this review, the in-situ open route is recommended for the situation with high flue gas CO2 concentration and the target products of low-margin commodities, while the off-situ sealed route is suitable for the situation with low flue gas CO2 concentration and the target products of high value-added products.

Using Enzymes to Understand and Control the Local Environment of Catalysis

Local environments within porous electrodes are an inherent, but often neglected component of catalysis as the local conversion of reactants to products means catalysis occurs in a very different environment to bulk solution. By understanding and modifying these local environments using a combination of experimental and computational techniques, we show how to improve the performance of electrocatalytic reactions to address the climate crisis by efficiently converting renewable energy to chemical fuels. The selectivity and activity of enzymes means they are ideal model catalysts that can guide the design of synthetic systems. However, they must be in an environment that is close to their optimal to operate efficiently, with small changes in properties such as pH drastically affecting their activity. By optimising their local environment, the rates of fuel formation can be drastically (>18×) increased.[1] We also demonstrate the crucial role of CO2 hydration kinetics on the local pH and CO2 concentration using the enzyme Carbonic Anhydrase co-immobilised with Formate Dehydrogenase.[2] Carbonic Anhydrase catalyses CO2 hydration, causing CO2 to act as a better buffer to mitigate changes in the local pH environment allowing the system to operate closer to its optimal and how this contrasts with heterogeneous CO2 reduction. (fig. 1a)We extend this approach to low CO2 concentrations, taking inspiration from the natural carboxysome to develop a system where Formate Dehydrogenase and Carbonic Anhydrase are co-immobilised in a nanoconfined structure to improve low CO2 concentration utilisation. (fig. 1b).[3] The electrolysis of dilute CO2 streams suffers from low concentrations of dissolved substrate and its rapid depletion at the electrolyte-electrocatalyst interface. These limitations require first energy-intensive CO2 capture and concentration, before electrolyzers can achieve acceptable performances. For direct electrocatalytic CO2 reduction from low-concentration sources, we introduce a strategy that mimics the carboxysome in cyanobacteria by utilizing microcompartments with nanoconfined enzymes in a porous electrode. Carbonic Anhydrase accelerates CO2 hydration kinetics and minimizes substrate depletion by making all dissolved carbon available for utilization, while a highly efficient formate dehydrogenase reduces CO2 cleanly to formate; down to even atmospheric concentrations of CO2. This bio-inspired concept demonstrates that the carboxysome provides a viable blueprint for the reduction of low-concentration CO2 streams to chemicals by using all forms of dissolved carbon.

The requirement for external carbonic anhydrase in diatoms is influenced by the supply and demand for dissolved inorganic carbon.

Photosynthesis by marine diatoms contributes significantly to the global carbon cycle. Due to the low concentration of CO2 in seawater, many diatoms use extracellular carbonic anhydrase (eCA) to enhance the supply of CO2 to the cell surface. While much research has investigated how the requirement for eCA is influenced by changes in CO2 availability, little is known about how eCA contributes to CO2 supply following changes in the demand for carbon. We therefore examined how changes in photosynthetic rate influence the requirement for eCA in three centric diatoms. Modeling of cell surface carbonate chemistry indicated that diffusive CO2 supply to the cell surface was greatly reduced in large diatoms at higher photosynthetic rates. Laboratory experiments demonstrated a trend of an increasing requirement for eCA with increasing photosynthetic rate that was most pronounced in the larger species, supporting the findings of the cellular modeling. Microelectrode measurements of cell surface pH and O2 demonstrated that individual cells exhibited an increased contribution of eCA to photosynthesis at higher irradiances. Our data demonstrate that changes in carbon demand strongly influence the requirement for eCA in diatoms. Cell size and photosynthetic rate will therefore be key determinants of the mode of dissolved inorganic carbon uptake.

Enhancement of CO2 adsorption performance and widening of adsorption temperature window by co-doping different valence state metals on the Li4SiO4 (010) surface

Lithium silicate (Li4SiO4) has good stability, high theoretical carbon dioxide (CO2) adsorption capacity, and low regeneration temperature. It has great potential in the field of CO2 adsorption. However, it is difficult to achieve the theoretical value in practical applications and a narrow temperature window for adsorption. Therefore, further research in this area is urgently needed. In this study, experimental and simulation methods were used to investigate the effects of single doping and co-doping with K, Na, Be, Ca, and Al metals on the adsorption performance and adsorption temperature window of Li4SiO4. Single doping with K, Na, or Al makes CO2 easier to be adsorbed on the Li4SiO4 (010) surface by increasing the charge transfer from the Li4SiO4 surface to CO2. Co-doping with K and Al increases the adsorption energy of CO2 on the Li4SiO4 (010) surface, enhances hybrid peaks, and broadens the temperature range for CO2 adsorption on the Li4SiO4 surface. It exhibits stable cyclic adsorption performance under low CO2 (15% CO2, N2 balance) concentration, and more electron transfer facilitates the formation of carbonate species on the Li4SiO4 (010) surface at lower temperatures, thereby improving its CO2 adsorption performance.

Long-Term Forecasting of Air Pollution Particulate Matter (PM2.5) and Analysis of Influencing Factors

Long-term forecasting and analysis of PM2.5, a significant air pollution source, is vital for environmental governance and sustainable development. We evaluated 10 machine learning and deep learning models using PM2.5 concentration data along with environmental variables. Employing explainable AI (XAI) technology facilitated explainability and formed the basis for factor analysis. At a 30-day forecasting horizon, ensemble learning surpassed deep learning in performance, with CatBoost emerging as the top-performing model. For forecasting horizons of 90 and 180 days, Bi-SLTM and Bi-GRU, respectively, exhibited the highest performance. Through an analysis of influencing factors by SHAP, it was observed that PM10 exerted the greatest impact on PM2.5 forecasting. However, this effect was particularly pronounced at higher concentrations of CO. Conversely, at lower CO concentrations, the impact of increased PM10 concentrations on PM2.5 was limited. Hence, it can be inferred that CO plays a pivotal role in driving these effects. Following CO, factors such as “dew point” and “temperature” were identified as influential. These factors exhibited varying levels of linear correlation with PM2.5, with temperature showing a negative correlation, while PM10, CO, and dew point generally demonstrated positive correlations with PM2.5.

Features of the Scaling of the Anomalous Hall Effect in (CoFeB)x(LiNbO3)100 − x Nanocomposite Films Below the Percolation Threshold: Manifestation of the Cotunneling Hall Conductance?

A scaling behavior of the anomalous Hall effect resistivity ρAHEversus the longitudinal resistivity ρ in (CoFeB)x(LiNbO3)100 −xnanocomposites with a low content of dispersed Co and Fe atoms (Nd~ 4 × 1020cm−3) in an amorphous LiNbO3matrix is studied in the rangex≈ 40–48 at % below the percolation thresholdxp≈ 49 at %. A logarithmic temperature dependence of the conductivity σ ~ lnT has been observed in the rangex≈ 44–48 at %, which is transformed in the rangex≈ 40–42 at % to a square root law lnσ ∝ ‒(T0/T)1/2, which is characteristic of cotunneling transport processes in nanocomposites. It has been found that the exponentn≈ 0.24 in the scaling law ρAHE/x∝ [ρ(x)]ncoincides within an accuracy of 5% with the exponentnin a similar dependence for nanocomposites based on the (CoFeB)x(Al2O3)100 −xmatrix with a high contentNd~1021–1022cm–3and with the exponentnin a parametric dependence ρAHE∝ [ρ(T)]nfor the samples with the minimum contentx≈ 40 at %. The found features are attributed to the correlated change in the probability of cotunneling transitions in a set of more than three centers under the effect of spin–orbit coupling. The manifestation of the barrier tunneling anomalous Hall effect at granule interfaces is also p-ossible.

Effect of Various Acid Solutions on the CO2 Dissolution Rate, Morphology, and Particle Size of Precipitated Calcium Carbonate Synthesized Using Seashells.

In this study, the influence of acid solutions on the production of precipitated calcium carbonate (PCC) using seashells was investigated. In terms of the Ca dissolution efficiency and atmosphere for dissolving CO32-, the results indicate that HCl, HNO3, CH3COOH, and HCOOH at 1.0 M were the most ideal among the acid solutions. The use of weak acids resulted in the low degree of dissolution of Al and Fe. These impurities could be mostly removed through the pH adjustment process, leading to PCC with a purity of 99% or more. Further, CH3COOH and HCOOH exhibited low CaCO3 carbonation efficiency owing to the hydrogen bonding of the carboxyl group and its hindering effect on the growth of CaCO3 particles. In addition, in the presence of the carboxyl group, the morphology tended to be oval, and the particle size was small. Particularly, when CH3COOH was used, the combined effect of the low initial Ca ion concentration and slow CO2 dissolution rate resulted in minimal changes during the carbonation time and the smallest particle size. However, variations in the degree of Ca concentration with a change in the acid solution concentration influenced the dominance of nucleation and particle growth, leading to variations in the particle size. The results of this study revealed that when manufacturing PCC using seashells, the appropriate acid solution must be selected to obtain the required PCC properties.

Pilot-scale study of sorption-enhanced gasification of sewage sludge

Sustainable management and disposal alternatives for sewage sludge (SS) should be pursued due to the substantial increment in its global production, as well as due to the raising interest in the renewable energy and synthetic fuels deployment. Since SS present high moisture (>95 % wt.), drying would play an essential role in SS management. In this work, SS pre-treated in a solar-drying facility has been successfully used as feedstock in a 30 kWth bubbling fluidised-bed (BFB) gasification pilot plant operating under Sorption Enhanced Gasification (SEG) conditions, i.e. using CaO as bed material and steam as gasifying agent. The influence of key operating SEG parameters (such as temperature, steam-to-carbon ratio and sorbent-to biomass proportion) in the syngas yield and composition (H2, CO, CO2, CH4, CxHy, H2S, COS, NH3 and tars) has been carefully assessed. As a matter of comparison, steam-oxygen gasification conditions have been also tested in the facility using solar-dried SS as feedstock. The results obtained demonstrate the possibility of producing a syngas with high H2 contents of 70–73 vol% and relatively low CO and CO2 contents (i.e. 2–3 vol% and 8 vol% respectively).

Carbon capture from low CO2 concentration stream through ternary alkali metal nitrates promotion of MgO sorbents at intermediate temperature and low space velocity

Many MgO sorbents exhibit high CO2 uptake in the presence of high concentration CO2 and aided by high space velocity, which unfortunately leads to low CO2 capture efficiency from the gas stream. This study investigates the effect of Li/Na/K ratio on sorption performance in dilute CO2 streams (15% CO2) using alkali metal nitrates-promoted MgO sorbents at a low space velocity of 20 ml/g·min in fixed bed reactor. Study shows that the ratio of Li/Na/K in ternary alkali nitrate salt mixture significantly affects the induction periods for the second phase CO2 sorption, which is a key contributor to high CO2 uptake. High LiNO3 content in ternary mixture leads to long induction period, and therefore lower CO2 capacity during the 4 h period. Conversely, high ratios of NaNO3 and KNO3 leads to shorter induction periods. Among the samples, MgO with 9 mol% (Li0.18Na0.52K0.3) exhibits the highest CO2 sorption capacity of 5.56 mmol/g at 240°C in 4 h (20.6% CO2 capture efficiency) and 3.18 mmol/g after 5 cycles (10.8% CO2 capture efficiency). Comparative studies show that optimal temperatures for CO2 sorption are higher when using pure CO2 (280 to 320°C) than when using 15% CO2 (240°C) due to the thermodynamic equilibrium. CO2-TPD results indicate that CO2 desorption proceeds in two phases similar to CO2 sorption, and the presence of alkali salt in MgO also promotes the decomposition of bulk carbonate to CO2. It is shown that molten salt migration and agglomeration of MgO particles are likely the factors that lead to decline in CO2 uptake over the sorption-desorption cycles.

Properties of Carbonated Steel Slag Admixture in the Cementitious System

Global warming caused by carbon dioxide (CO2) emissions has emerged as an undeniable environmental concern. While advocating for energy conservation and emissions reduction, the challenge of addressing the substantial CO2 emissions cannot be underestimated. Currently, steel slag is utilized in carbon capture and storage technology due to its potential for carbonation. However, the carbonation of steel slag necessitates a stable and cost-effective carbon source. Industrial exhaust gases are considered a viable option, but they often have low CO2 concentrations, resulting in sluggish carbonation rates. Therefore, this study focuses on directly converting steel slag powder into concrete mineral admixtures to enhance the carbonation rate at low CO2 concentrations. Experimental results reveal that a carbonation time of 3–7 days, a liquid–solid ratio of 50%, and the selection of sodium silicate as the alkali activator yield the optimal carbonation conditions. Under these conditions, the CO2 uptake can reach 15.3%–16.0%, and the f-CaO content can be reduced to 0.2%–0.3%. Mixing 30% carbonated steel slag powder with P·Ⅰ 42.5 cement in mortar samples yields a compressive strength of 32.1 MPa at 7 days and 47.5 MPa at 28 days, along with a flexural strength of 6.2 MPa at 7 days and 8.0 MPa at 28 days. The addition of carbonated steel slag powder not only enhances the mechanical properties but also reduces the pore diameter in the hardened cementitious system. In 7 days, the pore size decreases from being concentrated around 349 nm to approximately 282 nm, and in 28 days, the pore size decreases from being concentrated around 62 nm to roughly 55 nm. This transformation is primarily attributed to the role played by calcite grains in the carbonated steel slag powder, which facilitates nucleation and filling effects.

Evaluation of photobiomodulation therapy (PBMT) on salivary flow and composition in head and neck cancer patients undergoing radiation therapy

Assess the impact of photobiomodulation therapy (PBMT) on xerostomia, salivary flow rate (SFR) and composition in patients undergoing radiotherapy (RT) for head and neck cancer (HNC). Thirty patients undergoing RT (65 Gy) for HNC were enrolled. Saliva and xerostomia evaluations collected pre- and post-PBMT-RT. PBMT involved irradiation of extra and intraoral points, 15-20 sessions, 2-3 times/week. SFR, trace elements, total protein, alkaline phosphatase, xerostomia, and pH were analyzed. The average age was 60.7 years. After treatment, there was not a significant reduction in SFR and there was no difference on xerostomia. Significant reductions in Al, Cd, Fe, Ni, P, and Sb concentrations were observed, along with a significant increase in Mg concentration. Sample data were organized into 3 groups based on a self-organizing map. Low concentrations of Al, As, Co, Cr, Cu, Fe, Mn, Mo, S, Sr, and Zn were the primary discriminatory factors for group A, while group B consisted of post-PBMT-RT samples with high concentrations of Ca, K, Mg, Na, and S. PBMT prevented a significant reduction in SFR and xerostomia induced by radiation therapy. These findings suggest that PBMT prevents salivary gland damage minimizing the decline in salivary flow.

Adsorption behavior of atmospheric CO2 with/without water vapor on CeO2 surface

The significance of investigations into CO2 adsorption from the air has been steadily on the rise in recent years. CeO2 is known as an effective catalyst for CO2 transformation and adsorbent of CO2, however, the study on the adsorption of low concentrations of CO2 on CeO2 and the effect of water vapor on the adsorption of CO2 on CeO2 is very limited. Herein, the adsorption behavior of low concentration of CO2, particularly atmospheric CO2 (0.04 vol%), on CeO2 and the effect of water vapor on the CO2 adsorption were investigated by in situ FT-IR, mass spectroscopies, and DFT calculations. Low concentrations of CO2 can be effectively adsorbed on CeO2, and typical four CO2 adspecies such as bidentate carbonate, hydrogen carbonate, monodentate carbonate, and polydentate carbonate were formed on CeO2. The CO2 adsorption amount on CeO2 was increased by 20% by the presence of water vapor compared with that in the absence of water vapor. Based on FT-IR analyses and DFT calculations, the adsorption strength of CO2 is comparable to that of water on CeO2, and the water adspecies will assist the adsorption of CO2 via hydrogen bonding, leading to the increase of CO2 adsorption amount.

Preparation of cellulose nanofiber/Fe3O4/CaCO3 magnetic biocomposite by air capture and its application on purifying lead-contaminated water: Removal, immobilization and separation

Utilizing nature resource is one of the most effective ways to achieve sustainability development. In this work, super low-concentration CO2 in the atmosphere and rich and cheap biomaterial cellulose were used to prepare magnetic bio-composite, cellulose nanofiber/Fe3O4/CaCO3 (CFeCa). By capturing CO2 in air, Ca2+ was transformed into calcite CaCO3, which subsequently coated on cellulose nanofiber (CNF). Fe3O4 with about 50 nm in size were also observed to attach to the CNF. Thus, CNF bridged these two inorganic materials, which together fabricated stable composite with strong mutual coupling. The prepared CFeCa was applied to purify the lead-polluted water as water treatment agent. Its up-taken capacity for Pb2+ reached as high as 1010 mg·g−1. Almost 100% removal efficiency was attained, even treating Pb2+ wastewater in a wide concentration range from 5 to 250 ppm. Meanwhile, CFeCa is stable property during application. After running for 30 cycles, the treated water still met drinkable water standard. More importantly, the recovered lead was also bound on the surface of CNF, which make it easy to be separated from water and avoiding the risk of second pollution. Cheap raw materials and multiple merits of resulted composite offer CFeCa a perspective application as water treatment agent.

A study on photocatalytic Janus membrane reactor for direct conversion of low concentration carbon dioxide in air to methane: Effects of combination of two-dimensional carbon nanosheets

Large CO2 emissions cause the greenhouse effect, which threatens human survival. Directly converting CO2 in the air into energy and valuable resources is the most effective way to address the greenhouse effect. Currently, the main problem with CO2 conversion is the poor conversion efficiency owing to low CO2 concentrations in the air. In this study, a Janus membrane with the functions of concentrating CO2 (gas separation layer) and photocatalytic reaction (photocatalytic reaction layer) was fabricated. The Janus membrane directly converted extremely low concentrations of CO2 in the air into CH4. Amine-functionalized graphene oxide was added to regulate the CO2 conversion efficiency and the structure of the gas separation layer. Graphene was added to the photocatalytic reaction layer to suppress electron-hole recombination and increase the probability of excited electrons colliding with CO2. The experimental results showed that the modification of the gas separation layer or the photocatalytic reaction layer effectively increased the CH4 yield of the Janus membrane. By maintaining a balance between the selectivity and permeability coefficients of the gas separation layer, the highest methane yield (8.9 ppm) was obtained. The CH4 yield of the Janus membrane was further improved (8.9 ppm to 11.1 ppm) by modifying the photocatalytic reaction layer with graphene. This study proposes a feasible method for improving the efficiency of the Janus membrane for converting low-concentration CO2 in air to CH4.

Comparison on mortality, pupation, and emergence of Plodia interpunctella (hübner) treated by 2, 4, 6, and 8% carbon dioxide mixed with 2 and 4% oxygen at three temperatures

Low concentration CO2 (e.g., 2–8%) mixed with 2–4% O2 balanced by N2 is more economically feasible than applying 99.99% N2 alone. Mortality, pupation, and emergence of the fifth instar larvae of Plodia interpunctella (Lepidoptera: Pyralidae) were tested in 2 or 4% O2 mixed with 2, 4, 6, or 8% CO2 balanced by N2 at 28, 23, and 18 °C. Mortality of eggs, second instar larvae, and pupae was tested in the mixture of 2% O2, 4% CO2, and 94% N2 at the three temperatures. When fifth instar larvae were exposed in 2% O2 mixed with 0, 2, 4, 6, and 8% CO2 or increasing temperature, the LT50, LT99 value, and time reaching 100% mortality was decreased significantly. Exposing in 4% O2 mixed with 0, 2, 4, 6, and 8% CO2, the pupation and emergence of the surviving fifth instar larvae were also decreased significantly, and reduced more in higher temperatures. This study found 2, 4, 6, and 8% CO2 had additive effect to low O2 on insect mortality, pupation, and emergence at any tested temperature, and higher CO2 concentration or temperature resulted in a higher additive percentage. The fifth instar was the most tolerant stage to the gas mixtures followed by second instar larvae, pupae, and egg; and increasing temperature would sufficiently decrease the lethal exposure time.

Highly efficient catalytic direct air capture of CO2 using amphoyeric amino acid sorbent with acid‐base bi‐functional 3D graphene catalyst

Direct air capture (DAC) of CO2 is vital for combating global climate change, but DAC technologies have a low absorption efficiency due to the low concentration (∼400 ppm) of atmospheric CO2. A novel DAC technology was developed to solve this issue using lysine (an amino acid) as a sorbent and N-doped 3D graphene as an absorption/desorption-enhanced bifunctional catalyst. Introducing only 500 ppm N-3DG catalyst increased the working time (≥90% CO2 absorption efficiency) by 233% and its absorption capacity by 197%. The catalyst also significantly accelerated the CO2 working desorption capacity and rate by ∼280% and ∼338% at 70 °C, enabling regeneration of the sorbent by utilizing low-temperature waste heats. Furthermore, the excellent stability of the system was confirmed by 50 cyclic tests. The chemical mechanism driving catalytic CO2 capture was postulated and confirmed by density functional theory computations. This study provides a new strategy for developing next-generation DAC technologies.

Atmospheric CO2 controls on the MIS 6 glaciation: 10Be chronology of moraines in the Haizishan area, southeastern Tibetan Plateau

A unifying theory interpreting the cause of ice-age cycles remains elusive, in view of the near-synchronous interhemispheric major climate shifts but anti-phased summer solar insolation signatures between hemispheres. Determining the timing and magnitude of mountain glaciations helps in shedding new light on this long-standing unsolved puzzle. Yet, robust glacial chronologies are limited for the pre-Last Glaciation time periods, impeding a full understanding of glacial histories and climatic mechanisms behind them in mountainous regions, such as the Tibetan Plateau (TP). Here, we report thirty-five new 10Be exposure-ages from moraine boulders in the Niqingqu Valley, eastern Haizishan Plateau, which adds to the existing glacial chronologies of the Hengduan Mountains, southeastern TP. The dating results indicate that four centennial to millennial-scale glacial activities occurred around 168.4 ka in the studied valley. Despite being indistinguishable in age, these high-frequency glacial fluctuations allow us to draw a conclusion that glaciers in the studied valley achieved the marine isotope stage 6 (MIS 6) glacial maximum prior to the Penultimate Glacial Maximum (PGM), inconsistent with Northern Hemisphere. We attribute the MIS 6 glacial maximum identified here to the response of glaciers to a combination of low-level atmospheric CO2 content and low northern high-latitude summer solar insolation/high summer-monsoon precipitation. The consistent local PGM and low CO2 levels suggest that low atmospheric CO2 contents are likely a necessary prerequisite for the MIS 6 glaciation.

The EU carbon border adjustment mechanism: implications on Brazilian energy intensive industries

ABSTRACT As an instrument supporting the realization of EU climate neutrality targets by 2050 and encouraging decarbonization outside its borders, the current proposed Carbon Border Adjustment Mechanism (CBAM) is facing opposition from some countries. Focusing on Brazil, this paper evaluates the impacts of the CBAM on the Brazilian economy through a comprehensive analysis of various scenarios based on the potential EU implementation of the CBAM and Brazil’s climate scenarios. Results obtained in this research alleviate concerns of detrimental and competitiveness losses from Brazilian industries. Rather, the implementation of the EU CBAM improves the trade balance of Brazil’s Energy-Intensive Industries (EII). The relatively low CO2 contents of Brazilian EII are elemental to this result, while contributions of carbon-free technologies in electricity generation are also critical factors in maximizing this trade surplus. Other consequential factors affecting these results are the contributions of CO2 removal from Brazil’s forestry of land used, and homogeneity of CBAM-imposed products.

Activated char from the co-pyrolysis of polystyrene and olive stone mixtures for the adsorption of CO2

Yogurt plastic containers made of polystyrene (PS), olive stone, and mixtures of both have been converted into activated carbon materials transforming them firstly into char via pyrolysis and secondly with activation using either KOH or H2SO4. The pyrolysis of the olive stone gave a higher yield of material than the plastic PS. However, the activation of the PS char with KOH was more effective, reaching surface areas of 508 vs 194 m2 g−1 of the corresponding prepared with olive stone. The prepared materials were tested as CO2 adsorbent in thermobalance and fixed-be column assays. The materials activated with H2SO4 slightly enhanced the adsorption ability of the original char but were far from the performance obtained with KOH activation. The CO2 isotherms showed high synergy of CO2 uptake and selectivity when using activated chars prepared with the char from the mixture of raw materials, specially at a 1:1 mass ratio. The isosteric heat of adsorption values were those expected for a physisorption process. Further experiments in a fixed-bed column were also studied at atmospheric pressure at different inlet CO2 concentrations (10–50%). The CO2 retention increased as the partial CO2 pressure rose. Besides, a very similar performance of the material prepared with plastic and olive stones was obtained at 50%, i.e. 220 and 197 mg g−1 respectively. At low CO2 concentrations, the materials enriched with plastic displayed better performance than those prepared with olive stone. Cycles of adsorption-desorption were carried out in the column to assess the stability of the materials. The curves obtained did not display any substantial change, demonstrating the lack of adsorption retention.