Mol CO2 Research Articles

Techno-Economic Analysis of CO2 Capture from Pulp and Paper Mill Limekiln

This paper presents a techno-economic analysis of an absorption-based CO2 capture process using Monoethanolamine (MEA) as the solvent for pulp and paper mill limekiln. The flue gas specifications were obtained from published limekiln data of a theoretical pulp and paper mill. The process was simulated in Aspen Plus and linked to CAPCOST using a python script for the cost calculations. The CO2 capture cost estimates were compared to the only CO2 capture costs data available in the literature for limekiln flue gas. Comparing the cost breakdown between the published data and this study, the capital cost difference was found to be highest for the stripper and the compression and dehydration sections. Further, the capture cost sensitivity analysis, evaluating the impacts of key parameters, including flue gas CO2 mol%, MEA, electricity, and steam, showed that the capture costs varied from $70 to $82 per tonne of CO2 captured.

CO2 absorption with diamine functionalized deep eutectic solvents in microstructured reactors

Deep eutectic solvents (DESs) have gained much attention to capture CO2 nowadays because of their simpler synthesis, higher sustainability and better eco-friendly properties compared to ionic liquids and conventional amine sorbents. Herein, we analyzed the CO2 absorption performance of five novel diamine functionalized DESs in microstructured reactors (MSRs) with metal foams as packing materials. Interestingly, the DES functionalized with N-methyl-1,3-propanediamaine (MAPA) showed remarkable absorption performance without significant viscosity rise. The CO2 loading and absorption efficiency of this DES could reach 0.78 mol of CO2 / mol of diamine and 98% at the gas to liquid flow rate ratios of 640 and 240, respectively. Even computational studies showed that the ethylenediamine (EDA) functionalized DES had the highest CO2 uptake ability due to the low energy barrier, but sudden rise in viscosity of the EDA functionalized DES reduced its CO2 absorption ability compared to the MAPA functionalized DES. Further experiments indicated that the MAPA functionalized DES showed low heat of absorption and remarkable regeneration ability. Overall rate constant and absorption flux of this DES were higher than most previously used amine functionalized DESs. Consequently, the unification of this remarkable DES and microreactors has great process intensification potential for CO2 absorption.

The Regulation of O2 Spin State and Direct Oxidation of CO at Room Temperature Using Triboelectric Plasma by Harvesting Mechanical Energy.

Oxidation reactions play a critical role in processes involving energy utilization, chemical conversion, and pollutant elimination. However, due to its spin-forbidden nature, the reaction of molecular dioxygen (O2) with a substrate is difficult under mild conditions. Herein, we describe a system that activates O2 via the direct modulation of its spin state by mechanical energy-induced triboelectric corona plasma, enabling the CO oxidation reaction under normal temperature and pressure. Under optimized reaction conditions, the activity was 7.2 μmol h−1, and the energy consumption per mole CO was 4.2 MJ. The results of kinetic isotope effect, colorimetry, and density functional theory calculation studies demonstrated that electrons generated in the triboelectric plasma were directly injected into the antibonding orbital of O2 to form highly reactive negative ions O2−, which effectively promoted the rate-limiting step of O2 dissociation. The barrier of the reaction of O2− ions and CO molecular was 3.4 eV lower than that of O2 and CO molecular. This work provides an effective strategy for using renewable and green mechanical energy to realize spin-forbidden reactions of small molecules.

Syngas Components Recovery during Membrane Gas Separation

Membrane operations are a promising way of improving and adjusting the composition of the biomass gasification product – syngas – before it can be further transformed into fuels and energy. The presented study focuses on the recovery of individual components (H2, CO, CO2) during membrane separation under varying conditions – pressure difference and the feed composition. Model syngas mixtures with four different compositions containing between 12-24 %mol H2, 34-39 %mol CO and 43-49 %mol CO2 were tested under different pressure differences ranging from 1 to 8 bar (retentate pressure ranging from 2 to 10 bar, permeate pressure from 1 to 4 bar), at temperature 22 °C. Results of the study indicate exponential dependency existence between total pressure drop and the components recovery. The data were approximated with fixed parameter for minimal pressure difference for each component (p0 = 0.5 bar for H2 and p0 = 0.7 bar for CO2) and with variable exponent coefficients. The coefficients in exponent are strongly dependant on permeate pressure (ranging from 0.33 to 0.88 bar-1 for different permeate pressures for CO2 recovery) and vary with feed composition as well (from 0.75 to 0.83 bar-1 across different mixtures for CO2 at fixed permeate pressure).

Experimental comparison of performance and emissions of a direct-injection engine fed with alternative gaseous fuels

Performance and emissions of a direct-injection (DI) spark-ignition engine with high compression-ratio (15.5:1) fed with hydrogen, hydrogen-rich reformate, and methane are discussed. Differences in the particle formation with hydrogen and the reformate containing 75% mol H2 and 25% mol CO2 are investigated for the first time and compared with methane. The total particle number (PN) concentration with the reformate was the highest at all loads because of its significantly longer injection duration. This new finding explains why the elevated PN emission was measured in a DI engine fed with the reformate in contrast to the previously published data for hydrogen and the reformate PFI engines. Hydrogen combustion resulted in higher particle formation compared to methane under high engine loads. The combined effect of the flame quenching distance, fuel carbon content, and injection duration defines the PN formation in a DI ICE fed with gaseous fuel. The study findings demonstrated the appearance of an optimal hydrogen injection strategy enabling the minimization of PN emission. Hydrogen combustion results in the highest engine thermal efficiency. However, when the exhaust waste heat utilization in the engine with the reformate combustion is considered, the overall system thermal efficiency above that of the hydrogen engine is achieved. Negligible and the lowest, in comparison to hydrogen and methane, NOx emissions are found with the reformate-fed engine. CO2 contained in the reformate acts as an inherent EGR enabling almost full mitigation of NOx formation even at the highest engine loads.

Effect of Elevated CO2 on Biomolecules' Accumulation in Caraway (Carum carvi L.) Plants at Different Developmental Stages.

Caraway plants have been known as a rich source of phytochemicals, such as flavonoids, monoterpenoid glucosides and alkaloids. In this regard, the application of elevated CO2 (eCO2) as a bio-enhancer for increasing plant growth and phytochemical content has been the focus of many studies; however, the interaction between eCO2 and plants at different developmental stages has not been extensively explored. Thus, the present study aimed at investigating the changes in growth, photosynthesis and phytochemicals of caraway plants at two developmental stages (sprouts and mature tissues) under control and increased CO2 conditions (ambient CO2 (a CO2, 400 ± 27 μmol CO2 mol−1 air) and eCO2, 620 ± 42 μmol CO2 mol−1 air ppm). Moreover, we evaluated the impact of eCO2-induced changes in plant metabolites on the antioxidant and antibacterial activities of caraway sprouts and mature plants. CO2 enrichment increased photosynthesis and biomass accumulation of both caraway stages. Regarding their phytochemical contents, caraway plants interacted differently with eCO2, depending on their developmental stages. High levels of CO2 enhanced the production of total nutrients, i.e., carbohydrates, proteins, fats and crude fibers, as well as organic and amino acids, in an equal pattern in both caraway sprouts and mature plants. Interestingly, the eCO2-induced effect on minerals, vitamins and phenolics was more pronounced in caraway sprouts than the mature tissues. Furthermore, the antioxidant and antibacterial activities of caraway plants were enhanced under eCO2 treatment, particularly at the mature stage. Overall, eCO2 provoked changes in the phytochemical contents of caraway plants, particularly at the sprouting stage and, hence, improved their nutritive and health-promoting properties.

Effects of elevated CO2 and temperature on soybean growth and gas exchange rates: A modified GLYCIM model

GLYCIM is a comprehensive soybean crop simulator that simulates soil, plant, and atmospheric interactions at the physical and physiological process level. The current research focused on replacing the original photosynthesis equation with a leaf-level coupled energy balance model of photosynthesis, transpiration, and stomatal conductance to more accurately simulate responses to climate change. Soybean gas exchange and growth data from six SPAR (Soil–Plant–Atmosphere Research) chamber experiments at four temperature treatments (24/18 °C, 28/22 °C, 32/26 °C, and 36/30 °C, respectively) under ambient (457 µmol mol−1) CO2 and two temperature treatments (28/22 °C and 32/26 °C, respectively) under elevated (670 µmol mol−1) CO2 were used to evaluate the ability of two GLYCIM model versions, original and modified, for simulating the responses of canopy photosynthesis, transpiration rates and observed harvest data. Simulation results showed that the modified GLYCIM had significantly better agreement with observed canopy photosynthetic and transpiration rates, as exhibited by higher values of IA (seasonal photosynthesis, average 0.86 versus 0.82; transpiration, average 0.95 versus 0.84) and lower values of RMSE (seasonal photosynthesis, average 0.58 versus 0.64 mol CO2 m−2 season−1; transpiration, average 1.99 versus 3.16 mmol H2O m−2 s−1) when compared to the original GLYCIM. The simulation of carbon partitioning to stems, leaves, pod and seed was reasonably accurate for both versions, although leaf and stem growth were under-predicted at warmest temperature treatments at either CO2 level. Overall, the modified GLYCIM provided an improved fit of gas exchange and dry matter over a broad range of temperatures and CO2 levels. Given additional evaluation with field data, these improvements will be useful to study adaptation responses for projected warmer, CO2 enriched, climate.

Removing CO2 from Xenon anaesthesia circuits using an amino-acid ionic liquid solution in a membrane contactor

• System capacity increased from 3.50 to 4.97 mol CO 2 /kg IL when breathing cycles were simulated. • Higher amount of anaesthetic gas can be recycled when Xe is used. • Ion-exchange allows for releasing CO 2 enabling the reuse of the IL solution. The noble gas xenon possesses many characteristics of an ideal anaesthetic agent. However, its application is limited in daily clinical routine due to its elevated price. The present work proposes the use of a gas-ionic liquid membrane contactor system in anaesthesia closed-circuits, for the removal of carbon dioxide, to allow the recycling of the anaesthetic agents, as a route to enable the widespread use of xenon. In this work, different anaesthetic gas delivery conditions were simulated and explored, considering the use of different anaesthetic gas mixtures. The results obtained, using a cholinium lysinate ionic liquid solution as CO 2 absorbent, expressed high efficiency, especially when xenon was used as the inhalational anaesthetic, leading to an overall CO 2 mass transfer of 1.26 × 10 −5 m.s −1 . The ability of the proposed system to recover xenon allows to reduce drastically the cost per operation, which can be a step forward for the routine use of this gas on surgeries. Additionally, this work evaluates the use of thermal and chemical regeneration of the ionic liquid solution. It was found that the thermal regeneration approach was not adequate for the regeneration of the IL. On the other hand, the use of ion-exchange resins proved to be an efficient and simple strategy for IL regeneration, allowing for an easy integration in the proposed system. This study opens a new direction not yet explored that may lead to more efficient IL regeneration processes.

Fast biodegradation of long-alkanes by enhancing bacteria performance rate by per-oxidation

The long-alkanes biodegradation rate was generally found slow during widely used pre-oxidation combined with biodegradation for oil contamination treatment, resulting in long and unsustainable removal. In this study, different chitosan content was used to produce iron catalysts for pre-oxidation, and nutrients were added for the long-alkanes biodegradation experiment. Mechanism of Fenton pre-oxidation and improvement in the biodegradation rate of long-alkanes were studied by analyzing the change in organic matter and bacterial community structure, the amount and activity of bacteria in the biological stage, and the degradation amount long-alkanes hydrocarbon before and after pre-oxidation. Results showed that the destruction of bacteria greatly reduced when hydroxyl radical intensity decreased to 4.40 a.u.. Also, the proportion of humic acid-like was high (40.88%), and the community structure was slightly changed with the pre-oxidation for the fast biodegradation (FB) group. In the subsequent biodegradation, it was found that the degradation rate of each long-alkanes in the FB group increased significantly (C30: 4.18–8.32 mg/(kg·d)) with the increase of the degradation of long-alkanes (10–50%). Further studies showed that the high nutrient dynamics (6.05 mg/(kg·d)) of the FB group resulted in high bacteria performance rate (0.53 mol CO2 × log CFU/(104 g2 d)), which further accelerated the substrate transformation(41%). Therefore, the biodegradation rate of long-alkanes was increased (43.8 mg/(kg·d)) with the removal rate of long-alkanes of 76%. The half-life of long-alkanes for the FB group (64 d) was 33 d shorter than the slow biodegradation group (99 d). These results exhibited that pre-oxidation regulation can shorten the bioremediation cycle by improving the biodegradation rate of long-alkanes. This research has good engineering application value.

Amine-Infused Hydrogels with Nonaqueous Solvents: Facile Platforms to Control CO2 Capture Performance

Amine-infused hydrogels provide a facile platform for developing solid sorbents with improved CO2 capture performance relative to that of their liquid counterparts. In this study, we develop hydrogel materials that can be easily manufactured at a large scale and have high flow gas permeability characteristics, fast uptake kinetics, and minimal performance degradation after recycling, properties which are particularly important for applications in direct air capture (DAC). To overcome water loss issues associated with hydrogel materials for DAC, we have introduced high-boiling-point/nonaqueous solvent systems, which significantly lowered the solvent loss, leading to dramatically improved recyclability. Among the materials developed, cross-linked poly(N-2-hydroxyethylacrylamide) (PHEAA) infused with diethanolamine (DEA) exhibited 7.82 and 2.90 wt % CO2 uptake with pure CO2 and DAC, respectively. Interestingly, by changing the hydrogel platform between either a cross-linked superabsorbent [i.e., poly(acrylamide/sodium acrylate)], PHEAA, or poly(acrylamide) (PolyAA) and impregnating with different amines/solvents, the uptake kinetics could be controlled and significantly improved. In fact, the PolyAA system impregnated with DEA in ethylene glycol showed 90% of the total capacity (6.37%) in 350 s (vs 4300 s in the case of the PHEAA/DEA system) as well as an enhanced amine efficiency (0.76 vs 0.28 mol CO2 per amine). Thus, this study demonstrates the use of different nonaqueous solvents on readily synthesized hydrogel platforms to improve the DAC uptake efficiency and kinetics. The fast kinetics enable shorter adsorption/desorption cycles, which will be advantageous in improving the CO2 uptake selectivity and reducing the sorption of water in larger-scale implementations of this approach, in both urban and industrial applications.

Elevated CO2 concentration increases photosynthetic sensitivity to nitrogen supply of sorghum in a genotype-dependent manner

We hypothesized that elevated [CO2] only increases sorghum photosynthesis under low nitrogen availability and evaluated whether cultivars BRS373 (grain), BRS511 (saccharine) and BRS655 (forage) differ in their sensitivity to nitrogen and [CO2]. Plants were grown in growth chambers where air [CO2] was 400 (a[CO2]) or 800 (e[CO2]) μmol CO2 mol−1 and supplied with nutrient solution containing 211 (HN) or 48 (LN) ppm N for 45 days. Photosynthetic traits were measured in fully expanded leaves as well as leaf nitrogen and biomass accumulation. e[CO2] increased the sensitivity of photosynthesis to LN, with all sorghum cultivars having lower maximum Rubisco carboxylation rate, effective quantum efficiency of PSII and stomatal conductance at LN than at HN. As compared to HN, LN caused lower photosynthesis of BRS373 at a[CO2] and lower maximum PEPC carboxylation rate at e[CO2]. Actually, the metabolic limitation of photosynthesis by LN (Lm) was high in BRS373 at a[CO2] and slightly reduced at e[CO2]. On the other hand, Lm was increased in BRS511 and BRS655 at e[CO2]. Based on photosynthesis, the grain cultivar BRS373 was the most sensitive to LN. Although the number of leaves and of tillers and the leaf area were lower at LN than at HN for BRS373 and BRS655 after 45 days of growth, shoot biomass was not significantly affected. We found significant variation in photosynthetic responses to LN and e[CO2] among sorghum cultivars, likely associated with different patterns of nitrogen and carbon partitioning. Such findings must be considered when predicting crop performance in a changing environment.

Elevated CO2 Enhances Dynamic Photosynthesis in Rice and Wheat.

Crops developed under elevated carbon dioxide (eCO2) exhibit enhanced leaf photosynthesis under steady states. However, little is known about the effect of eCO2 on dynamic photosynthesis and the relative contribution of the short-term (substrate) and long-term (acclimation) effects of eCO2. We grew an Oryza sativa japonica cultivar and a Triticum aestivum cultivar under 400 μmol CO2 mol−1 air (ambient, A) and 600 μmol CO2 mol−1 air (elevated, E). Regardless of growth [CO2], the photosynthetic responses to the sudden increase and decrease in light intensity were characterized under 400 (a) or 600 μmol CO2 mol−1 air (e). The Aa1, Ae2, Ea3, and Ee4 treatments were employed to quantify the acclimation effect (Ae vs. Ee and Aa vs. Ea) and substrate effect (Aa vs. Ae and Ea vs. Ee). In comparison with the Aa treatment, both the steady-state photosynthetic rate (PN) and induction state (IS) were higher under the Ae and Ee treatments but lower under the Ea treatment in both species. However, IS reached at the 60 sec after the increase in light intensity, the time required for photosynthetic induction, and induction efficiency under Ae and Ee treatment did not differ significantly from those under Aa treatment. The substrate effect increased the accumulative carbon gain (ACG) during photosynthetic induction by 45.5% in rice and by 39.3% in wheat, whereas the acclimation effect decreased the ACG by 18.3% in rice but increased it by 7.5% in wheat. Thus, eCO2, either during growth or at measurement, enhances the dynamic photosynthetic carbon gain in both crop species. This indicates that photosynthetic carbon loss due to an induction limitation may be reduced in the future, under a high-CO2 world.

Numerical and experimental investigation on air distributor design of fluidized bed reactor of sawdust pyrolysis

An improved biomass conversion in a lab-scale fluidized bed reactor (FBR) is achieved by optimizing the air distributor orifice size and number. Two approaches for introducing air were numerically and experimentally examined. These included perforated plate and downward orifice sparger. 3 mm and 5 mm orifice diameters, and 7, 9 and 13 holes were simulated at flow velocities of 2, 4, 6, and 8 times the minimum fluidization velocity, Umf. The simulation results revealed that increasing the orifice number has a positive effect on gas holdup, particularly for the perforated plate, which showed a uniform distribution of bubbles. The sparger configuration produced larger bubbles sizes, which could lead to better recirculation of solid flux, while stagnant particle zones were observed at the lower section of both distributors.A pyrolysis unit is also inserted at the top of freeboard of the FBR. For perforated plate with 6Umf, the pyrolysis process achieved thermal and cold gas efficiencies of 82.91% and 52.03%, respectively, while combustible gases with 41.6%mol CO, 8.7%mol CH 4 and 2.17%mol HC, were obtained. For sparger pipe and 6U mf _sp, 35.33 ppm NOx and 111 ppm SO 2 were measured in flue gas from combustion process at bed region.

Foliar application of sulfur improved growth, yield and physiological attributes of canola (brassica napus L.) under heat stress conditions

Canola (Brassica napus) is a significant oilseed crop in the world, including in Pakistan. Increases in global temperatures will likely affect future plant species distribution, and could influence the survivability of individual species because of the relationship between temperature, germination and dormancy. The objective of this study was to improve heat tolerance in canola with the foliar application of sulfur. Therefore, a pot study was performed in a growth room at the Institute of Horticultural Sciences, University of Agriculture Faisalabad in 2017-2018 under controlled conditions. Two varieties of canola, i.e., Hyola-401 and 45S42, two levels of foliar sulfur (S0= 0 ppm and S1 500 ppm) treatments, and two temperature levels (T1=18 °C and T2=28 °C) were studied. Heat stress was imposed at the time of anthesis (55-60 days after emergence). Collected data indicated that morphological characters such as root shoot length and their fresh and dry weight showed better performance where foliar sulfur was applied either in heat stress as well as in control conditions where no heat stress was imposed. The photosynthetic rate (6.21 µ mole CO2 m−2/sec), stomatal conductance (0.12 µ mole CO2 m−2/sec) and intercellular CO2 concentration (346.13 µ mole CO2 m−2/sec) were improved in sulfur treatments under heat stress conditions while transpiration rate (0.51 mol H2O m−2 s−1) was decreased with foliar application of sulfur. Similarly, yield and yield components (No. of siliques per plant (23), No. of seeds per siliqua (20), 1000 seed weight (3.53 g) and overall yield (2.11 t/ha) increased where foliar sulfur was applied @ 500 ppm. Overall results concluded that the foliar application of sulfur may be helpful for plant tolerance against heat stress by improving the physiological attributes and yield characters in canola. Moreover, among the genotype of Brassica napus L, Hyola 401 performed better in comparison with genotype 45S42 where foliar applied sulfur under heat stress conditions.

Responses of 'Syrah' grapevine to deficit irrigation in the Brazilian semi-arid region

Grapevine growing in areas with low rainfall as the Brazilian semi-arid requires irrigation to full fill plant water demand. The objective of this study was to evaluate the physiological and yield responses of grapevine to irrigation strategies in the Lower Middle São Francisco Valley, in Petrolina, State of Pernambuco, Brazil. The experiment was carried out over three consecutive growing seasons of drip irrigated 'Syrah' grapevine, grafted on 1103 Paulsen and planted in an Ultisol (Soil Taxonomy, USA). Full irrigation (FI), regulated deficit irrigation (RDI), and deficit irrigation (DI) treatments were designed in a randomized block with four replications. Mostly soil moisture depletion was observed until 0.6 m soil depth while higher moisture values and their small variation over the time were observed below 0.6 m and until 1.20 m depth as consequence of dense soil layers. RDI and DI promoted moderate water stress in plants (pre-dawn water potential from −0.2 to 0.4 MPa), reducing water consumption and gas exchange. Intrinsic water use efficiency was higher in RDI and DI (121 and 115 µmol CO2 mol H20−1, respectively). Tritratable acidity reduced to 5.81 and 6.28 g L−1 tartaric acid as water deficit increased, except in the third season. Soluble solids were influenced by treatments only in the second season, when it decreased in FI plants (22.6° brix). Weight of 100 berries was influenced by treatments in all seasons, with lower values for DI and RDI grapevines (less than 155 g). Number (15) and weight (2.2 kg) of cluster per grapevine and yield (7284 kg) were significantly higher in FI only in the third growing season, while average cluster weight was greater in FI in the first and third seasons (84 and 149 g, respectively). Irrigation water productivity did not differ among irrigation strategies. Deficit irrigation strategies allowed water saving.

Intracanopy CO2 and light interactions on Humulus lupulus L. net canopy carbon gain under current and future atmospheric CO2 concentrations

Photosynthetic light response curves were measured in four cultivars of Humulus lupulus L. (hop) at CO2 concentrations of 415, 500, 600, and 700 μmol CO2 mol−1. Short-term elevated CO2 increased net photosynthesis (An), light-saturated rates of photosynthesis, and quantum yield and decreased the light compensation point and leaf respiration. To illustrate the effects on canopy carbon gain, we used a rigorously validated physiologically-explicit canopy process model (MAESTRA). The cultivar-specific leaf-level physiological response parameters at 415, 500, 600, and 700 μmol CO2 mol−1 were extrapolated throughout the canopy to reproduce the cultivar-specific carbon gain under current and future atmospheric CO2 conditions. Under sub optimal light conditions, the initial CO2 increase of 415 to 500 μmol CO2 mol−1 resulted in the highest relative carbon gain increase (∼18%), whereas enrichment from 500 to 600 and 600 to 700 μmol CO2 mol−1 resulted in an additional carbon uptake of ∼16% and ∼12%. Ratios of An to increased CO2 indicated that shaded leaves benefit more from elevated CO2 than light saturated leaves. Estimated daily canopy carbon uptake increased ∼24% from 415 to 500 µmol mol−1 CO2. Daily carbon uptake increased by ∼17% from 500 to 600 µmol mol−1 CO2 and ∼18% from 600 to 700 µmol mol−1. Thus, in comparison to leaves exposed to direct sunlight, hop canopy carbon gain in shaded diffuse light lower canopy layers may contribute a greater proportion of total canopy carbon in future atmospheric CO2 conditions.

Alteration in biochemical constituents and nutrients partitioning of Asparagus racemosus in response to elevated atmospheric CO2 concentration.

Understanding the response of medicinal plants to elevated CO2 concentrations is crucial to evaluate the climate change impacts on medicinal plant's productivity together with the accumulation of biochemical constituents counting nutrients wealth. The present study investigated the effect of elevated CO2 concentrations (ambient-~400±4, 600±12, and 800±16 μmol CO2 mol-1) on the biochemical constituents (viz. chlorophyll, carotenoids, ascorbic acid, protein, total sugars, and carbon partitioning) and accumulation of mineral nutrients (viz. potassium, phosphorus, and magnesium) in different plant parts (viz. leaf, stem, and root) of Asparagus racemosus Willd., an endangered medicinal plant species. The results confirmed that the elevated CO2 concentration significantly (p ≤ 0.05) enhanced the leaves biochemical constituents, viz. chlorophyll, protein, total sugars, and carbon content while conversely diminishes the ascorbic acid content in leaf. The accumulation of nutrients especially potassium and magnesium were significantly (p ≤ 0.05) improved while it is reverse in case of phosphorus under the elevated CO2 concentration. Moreover, elevated CO2 notably altered protein, sugars, carbon, and nutrients partitioning in leaf, stem, and root tissues. This study will be helpful in anticipating the effect of rising atmospheric CO2 concentration on medicinal and threatened plants and require further intensive studies to comprehend the effects of elevated CO2 concentration.

Influence of Leachate and Nitrifying Bacteria on Photosynthetic Biogas Upgrading in a Two-Stage System

Photosynthetic biogas upgrading using two-stage systems allows the absorption of carbon dioxide (CO2) in an absorption unit and its subsequent assimilation by microalgae. The production of microalgae requires large amounts of nutrients, thus making scale-up difficult and reducing economic feasibility. The photosynthetic process produces oxygen (O2) (1 mol per mol of CO2 consumed), which can be desorbed into purified biogas. Two-stage systems reduce its impact but do not eliminate it. In this study, we test the use of landfill leachate as a nutrient source and propose a viable and economical strategy for reducing the O2 concentration. First, the liquid/gas (L/G) ratio and flow mode of the absorber were optimized for 20% and 40% CO2 with COMBO medium, then landfill leachate was used as a nutrient source. Finally, the system was inoculated with nitrifying bacteria. Leachate was found to be suitable as a nutrient source and to result in a significant improvement in CO2 absorption, with outlet concentrations of 0.01% and 0.6% for 20% and 40% CO2, respectively, being obtained. The use of nitrifying bacteria allowed a reduction in dissolved oxygen (DO) concentration, although it also resulted in a lower pH, thus making CO2 uptake slightly more difficult.

Diamine based water‐lean CO2 solvent with extra high cyclic capacity and low viscosity

AbstractThe industrial application of emerging water‐lean solvents to CO2 capture from flue gas is challenged by their high viscosity. In this work, we report a novel water‐lean CO2 solvent which possesses lower viscosity and higher CO2 cyclic capacity than other water‐lean solvents reported in the literature. The new solvent consists of N, N‐dimethyl‐1, 2‐ethanediamine (DMEDA), physical cosolvent N‐methyl‐2‐pyrrolidone (NMP) and up to 15% water (named ENH). We evaluated the effect of the solvent composition on the viscosity, CO2 cyclic capacity and regeneration energy of ENH and compared it with the reference monoethanolamine (MEA) based solvents. It was found that ENH containing 5% H2O (ENH‐5%H2O) with a CO2 loading of 0.767 mol CO2·mol amine–1 had a viscosity of 7.603 mPa·S at 40 ˚C, which was comparable with that of traditional blended amines. Excellent cyclic capacity performance was also observed, with ENH‐5% H2O showing a 140% improvement compared to aqueous MEA. Regeneration energy of ENH‐5% H2O was estimated to be 2.418 GJ·tCO2–1 which is 36% lower than the 30 wt. % aqueous MEA solvent. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.

Lepidium sativum Sprouts Grown under Elevated CO2 Hyperaccumulate Glucosinolates and Antioxidants and Exhibit Enhanced Biological and Reduced Antinutritional Properties.

The nutritional and health-promoting properties of plants are largely determined by their tissue chemistry. Tuning growth conditions could affect the accumulation of phytochemicals and, therefore, enhance the biological activities. Herein, the impact of elevated CO2 (eCO2; 620 µmol CO2 mol−1 air) on growth and chemical composition of sprouts of three Lepidium sativum cultivars (Haraz, Khider and Rajab) was investigated. Changes in the sprout actions against some human chronic diseases were evaluated. eCO2 induced biomass accumulation (1.46-, 1.47- and 2-fold in Haraz, Khider and Rajab, respectively) and pigment accumulation and reduced the level of antinutrients in L. sativum cultivars. Compared to the control, eCO2 induced total glucosinolate accumulation (0.40-, 0.90- and 1.29-fold in Khider, Haraz and Rajab, respectively), possibly through increased amino acid production, and their hydrolysis by myrosinase. In line with increased polyphenol production, improved phenylalanine ammonia lyase activity was observed. The antioxidant, anti-inflammatory, hypocholesterolemic, antibacterial and anticancer activities of the produced sprouts were significantly improved by sprouting and eCO2 exposure. PCA indicated that the cultivars showed interspecific responses. Thus, the present study confirms the synergistic effect of sprouting with eCO2 exposure as a promising approach to produce more bioactive L. sativum sprouts.