Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 7.472
Filtrar
1.
Pak J Pharm Sci ; 37(1(Special)): 235-243, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38747275

RESUMO

Stimulus-responsive mesoporous silica nanoparticles (MSNs) have displayed great potentiality for controlled-release and targeted drug delivery. In the current work, a supercritical fluid method was utilized to successfully prepare cinnamon oil loaded into chitosan grafted MSNs (CO@CS-MSNs). The influencing factors of drug loads, such as pressure, temperature, impregnation time and depressure time, were investigated. The structure of CO@CS-MSNs was demonstrated with Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscope (TEM), scanning electron microscopy (SEM), thermogravimetry (TG) as well as X-ray diffraction (XRD). The drug release assays in vitro at various pH conditions displayed that CO@CS-MSNs had an excellent pH-responsive release behavior, which confirmed that CO was loaded successfully into the CO@CS-MSNs. The findings indicated that the supercritical fluid approach is a non-destructive and efficient approach for stimulus-responsive MSNs, which is expected to further expand its application range.


Assuntos
Dióxido de Carbono , Quitosana , Cinnamomum zeylanicum , Liberação Controlada de Fármacos , Nanopartículas , Dióxido de Silício , Quitosana/química , Dióxido de Silício/química , Nanopartículas/química , Concentração de Íons de Hidrogênio , Dióxido de Carbono/química , Porosidade , Cinnamomum zeylanicum/química , Portadores de Fármacos/química , Óleos Voláteis/química , Óleos Voláteis/administração & dosagem , Difração de Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Microscopia Eletrônica de Varredura , Preparações de Ação Retardada
2.
Biomacromolecules ; 25(5): 2925-2933, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38691827

RESUMO

A "one-step" strategy has been demonstrated for the tunable synthesis of multifunctional aliphatic polycarbonates (APCs) with ethylene oxide (EO), ethylene carbonate (EC), and cyclohexene oxide (CHO) side groups by the copolymerization of 4-vinyl-1-cyclohexene diepoxide with carbon dioxide under an aminotriphenolate iron/PPNBz (PPN = bis(triphenylphosphine)-iminium, Bz = benzoate) binary catalyst. By adjusting the PPNBz-to-iron complex ratio and incorporating auxiliary solvents, the content of functional side groups can be tuned within the ranges of 53-75% for EO, 18-47% for EC, and <1-7% for CHO. The yield and molecular weight distribution of the resulting multifunctional APCs are affected by the viscosity of the polymerization system. The use of tetrahydrofuran as an auxiliary solvent enables the preparation of narrow-distribution polycarbonates at high conversion. This work presents a novel perspective for the preparation of tailorable multifunctional APCs.


Assuntos
Dióxido de Carbono , Cimento de Policarboxilato , Polimerização , Dióxido de Carbono/química , Cimento de Policarboxilato/química , Compostos de Epóxi/química , Óxido de Etileno/química , Cicloexenos/química , Catálise , Viscosidade , Dioxolanos
3.
Environ Sci Technol ; 58(20): 8724-8735, 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38717952

RESUMO

Building and protecting soil organic carbon (SOC) are critical to agricultural productivity, soil health, and climate change mitigation. We aim to understand how mechanisms at the organo-mineral interfaces influence SOC persistence in three contrasting soils (Luvisol, Vertisol, and Calcisol) under long-term free air CO2 enrichment conditions. A continuous wheat-field pea-canola rotation was maintained. For the first time, we provided evidence to a novel notion that persistent SOC is molecularly simple even under elevated CO2 conditions. We found that the elevated CO2 condition did not change the total SOC content or C forms compared with the soils under ambient CO2 as identified by synchrotron-based soft X-ray analyses. Furthermore, synchrotron-based infrared microspectroscopy confirmed a two-dimensional microscale distribution of similar and less diverse C forms in intact microaggregates under long-term elevated CO2 conditions. Strong correlations between the distribution of C forms and O-H groups of clays can explain the steady state of the total SOC content. However, the correlations between C forms and clay minerals were weakened in the coarse-textured Calcisol under long-term elevated CO2. Our findings suggested that we should emphasize identifying management practices that increase the physical protection of SOC instead of increasing complexity of C. Such information is valuable in developing more accurate C prediction models under elevated CO2 conditions and shift our thinking in developing management practices for maintaining and building SOC for better soil fertility and future environmental sustainability.


Assuntos
Dióxido de Carbono , Carbono , Solo , Dióxido de Carbono/química , Solo/química , Mudança Climática
4.
Anal Chim Acta ; 1307: 342620, 2024 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-38719413

RESUMO

BACKGROUND: Pharmacokinetic studies are pivotal in drug development, focusing on absorption, distribution, and excretion of active compounds. Effective sample preparation methods play a crucial role in these studies. Traditional techniques like protein precipitation and liquid-liquid extraction often involve toxic solvents and are time-consuming. Recently, deep eutectic solvent (DES) has emerged as an eco-friendly alternative due to its high efficiency, low cost, and low toxicity. This study introduces a novel sample pretreatment method using CO2-switchable DES in liquid-liquid microextraction (LLME) to enhance speed, accuracy, and sensitivity in complex biological samples analysis. RESULTS: A liquid-liquid microextraction sample pretreatment method based on switchable DES combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established for the analysis of urine and tissue samples. The method was optimized through systematic investigation of key parameters, including DES type, volume, molar ratio, pH, vortex time, gas purge time, and salt addition. The resulting procedure exhibited satisfying linearity (r2 ≥ 0.9958), good precision (RSD ≤6.01 %), desirable recovery (52.44%-98.12 %) and matrix effect (86.22%-119.30 %), and the accuracy and precision of stability were within the ±15 % limit. The proven methods were further applied to urinary excretion study and tissue distribution study of Nelumbinis plumula (NP) extract. The results indicated that the total cumulative excretion of liensinine, isoliensinine and neferine in urine within 240 h was 4.96 %, 0.66 % and 0.44 %, respectively. The tissue distribution study showed that alkaloids mainly distribute in liver, kidney, and spleen. SIGNIFICANCE: This research introduces a groundbreaking technique distinguished by its simplicity, speed, cost-effectiveness, and environmental friendliness. This approach, utilizing CO2-switchable DES as an extraction solvent for LLME, integrates deproteinization and removal of interfering molecules into a single step. This integration showcases its efficiency and convenience, demonstrating significant promise for various applications in the analysis of biological samples. Additionally, this study provides the first report on urinary excretion and tissue distribution of alkaloids from NP using a DES-LLME method. These findings offer valuable insights into the in vivo behavior of herbal medicine, enhancing understanding of pharmacological actions and facilitating clinical rational administration.


Assuntos
Dióxido de Carbono , Solventes Eutéticos Profundos , Microextração em Fase Líquida , Espectrometria de Massas em Tandem , Microextração em Fase Líquida/métodos , Dióxido de Carbono/química , Solventes Eutéticos Profundos/química , Animais , Distribuição Tecidual , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida de Alta Pressão , Masculino , Ratos , Ratos Sprague-Dawley
5.
J Transl Med ; 22(1): 339, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38594760

RESUMO

One of the most effective strategies to fight viruses and handle health diseases is vaccination. Recent studies and current applications are moving on antigen, DNA and RNA-based vaccines to overcome the limitations related to the conventional vaccination strategies, such as low safety, necessity of multiple injection, and side effects. However, due to the instability of pristine antigen, RNA and DNA molecules, the use of nanocarriers is required. Among the different nanocarriers proposed for vaccinal applications, three types of nanovesicles were selected and analysed in this review: liposomes, transfersomes and niosomes. PubMed, Scopus and Google Scholar databases were used for searching recent papers on the most frequently used conventional and innovative methods of production of these nanovesicles. Weaknesses and limitations of conventional methods (i.e., multiple post-processing, solvent residue, batch-mode processes) can be overcome using innovative methods, in particular, the ones assisted by supercritical carbon dioxide. SuperSomes process emerged as a promising production technique of solvent-free nanovesicles, since it can be easily scaled-up, works in continuous-mode, and does not require further post-processing steps to obtain the desired products. As a result of the literature analysis, supercritical carbon dioxide assisted methods attracted a lot of interest for nanovesicles production in the vaccinal field. However, despite their numerous advantages, supercritical processes require further studies for the production of liposomes, transfersomes and niosomes with the aim of reaching well-defined technologies suitable for industrial applications and mass production of vaccines.


Assuntos
Lipossomos , Vacinas , Lipossomos/química , Dióxido de Carbono/química , Solventes , DNA , RNA
6.
PLoS One ; 19(4): e0299831, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38635503

RESUMO

This article examines the role of legal structure in explaining financial development in twenty-three emerging markets, which has not been explored in institutional economics literature before. This study relied on Pedroni, and Kao cointegration tests, which is followed by the renowned panel cointegration technique. The results of the Pedroni and Kao cointegration tests show that the variables understudy is cointegrated in the long-run. These findings are confirmed by the panel cointegration showing that legal structure (LS) has positive impact on financial development (FIND) in long-run that support Law and Finance, and New Institutional Economics theories in emerging markets. This study is the first to directly examine the long-run impact of LS on FIND in emerging markets, and the result remains consistent across alternative measure of FIND. The findings of this study have important policy implications for emerging markets. Policymakers should focus on creating a legal environment that is conducive to financial development. This includes strengthening the legal framework, improving regulatory regimes, and promoting market autonomy. Additionally, policymakers should work to attract foreign investment, which can help spur economic growth and development in emerging markets. The findings of the study are consistent across battery of robustness testing.


Assuntos
Dióxido de Carbono , Desenvolvimento Econômico , Dióxido de Carbono/química , Investimentos em Saúde , Internacionalidade , Políticas
7.
Environ Sci Technol ; 58(16): 7196-7207, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38597822

RESUMO

Aerosols produced in the amine carbon capture process can lead to secondary environmental pollution. This study employs molecular dynamics (MD) simulations to investigate cluster formation, amine behavior, and aerosol growth of amines, essential for reducing amine aerosol emissions. Results showed that the cluster evolution process can be divided into cluster formation and growth in terms of molecular content, and the nucleation rate for the present systems was estimated in the order of 1028 cm-3 s-1. CO2 absorption was observed alongside successful nucleation, with CO2 predominantly localizing in the cluster's outer layer postabsorption. Monoethanolamine (MEA) exhibited robust electrostatic interactions with other components via hydrogen bonding, leading to its migration toward regions where CO2 and H2O coexisted within the cluster. While MEA presence markedly spurred cluster formation, its concentration had a marginal effect on the final cluster size. Elevating water content can augment the aerosol growth rate. However, altering the gas saturation is possible only within narrow confines by introducing vapor. Contrarily, gas cooling introduced dual, opposing effects on aerosol growth. These findings, including diffusion coefficients and growth rates, enhance theoretical frameworks for predicting aerosol formation in absorbers, aiding in mitigating environmental impacts of amine-based carbon capture.


Assuntos
Aerossóis , Dióxido de Carbono , Dióxido de Carbono/química , Simulação de Dinâmica Molecular , Aminas/química
8.
Environ Sci Technol ; 58(16): 6978-6987, 2024 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-38598712

RESUMO

Decarbonization of the cement sector is essentially required to achieve carbon neutrality to combat climate change. Amine-based CO2 capture is a leading and practical technology to deeply remove CO2 from the cement industry, owing to its high retrofittability to existing cement plants and extensive engineering experience in industrial flue gas decarbonization. While research efforts have been made to achieve low-carbon cement with 90% CO2 removal, a net-zero-emission cement plant that will be required for a carbon neutrality society has not yet been investigated. The present study proposed an advanced amine-based CO2 capture system integrated with a cement plant to achieve net-zero CO2 emission by pushing the CO2 capture efficiency to 99.7%. Monoethanomaine (MEA) and piperazine/2-amino-2-methyl-1-propanol (PZ-AMP) amine systems, which are considered to be the first- and second-generation capture agents, respectively, were detailed investigated to deeply decarbonize the cement plant. Compared to MEA, the advanced PZ-AMP system exhibited excellent energy performance with a regeneration duty of ∼2.6 GJ/tonne CO2 at 99.7% capture, 39% lower than the MEA process. This enabled a low CO2 avoided cost of $72.0/tonne CO2, which was 18% lower than that of the MEA-based zero-emission process and even 16.2% lower than the standard 90% MEA process. Sensitivity analysis revealed that the zero-emission capture cost of the PZ-AMP system would be further reduced to below $56/tonne CO2 at a $4/GJ steam production cost, indicating its economic competitiveness among various CO2 capture technologies to achieve a zero-emission cement plant.


Assuntos
Aminas , Dióxido de Carbono , Dióxido de Carbono/química , Aminas/química , Materiais de Construção
9.
Environ Sci Pollut Res Int ; 31(21): 31632-31645, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38648001

RESUMO

Integrating hydrogen with CNG is crucial for carbon neutrality and environmental goals, as it enhances flame temperature, reduces emissions, and combats global warming. This study employs the CHEMKIN tool to examine combustion characteristics, including adiabatic flame temperature, mole fraction, normalization, and production rate, in H2-CNG mixtures under various atmospheric and operating conditions. Blending 50% hydrogen with CNG results in significant changes, including a temperature increase from 2322 to 2344 K when the hydrogen content is at 50%. The introduction of hydrogen causes a notable 30-35% reduction in CH4 mole fraction and a simultaneous 26.6% increase in C-normalized CH4 production. Free radicals play a role in affecting CO2 production, with the normalization of CO species increasing from 0.068 to 0.087. Through NSGA-II multi-objective optimization methods, the study identifies a 50% H2-50% CNG blend as the optimal choice for thermal and environmental performance. The study explores the energy and environmental impacts of incorporating hydrogen into CNG-air combustion, with a specific focus on the effects of 50% H2 blending with CNG. Hydrogen blending benefits from elevated adiabatic flame temperature and increased free radical formation, ultimately leading to emission reduction. These findings firmly establish H2-CNG mixtures as promising environmentally friendly alternatives with superior combustion characteristics. Their potential paves the way for significant progress towards achieving carbon neutrality and combating climate change through cleaner, more efficient fuel options.


Assuntos
Hidrogênio , Gás Natural , Hidrogênio/química , Dióxido de Carbono/química , Metano , Hidrogenação , Aquecimento Global
10.
J Photochem Photobiol B ; 255: 112924, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38688041

RESUMO

Whether rapid oxygen isotopic exchange between bicarbonate and water occurs in photosynthesis is the key to determine the source of oxygen by classic 18O-labeled photosynthetic oxygen evolution experiments. Here we show that both Microcystis aeruginosa and Chlamydomonas reinhardtii utilize a significant proportion (>16%) of added bicarbonate as a carbon source for photosynthesis. However, oxygen isotopic signal in added bicarbonate cannot be traced in the oxygen in organic matter synthesized by these photosynthetic organisms. This contradicts the current photosynthesis theory, which states that photosynthetic oxygen evolution comes only from water, and oxygen in photosynthetic organic matter comes only from carbon dioxide. We conclude that the photosynthetic organisms undergo rapid exchange of oxygen isotope between bicarbonate and water during photosynthesis. At the same time, this study also provides isotopic evidence for a new mechanism that half of the oxygen in photosynthetic oxygen evolution comes from bicarbonate photolysis and half comes from water photolysis, which provides a new explanation for the bicarbonate effect, and suggests that the Kok-Joliot cycle of photosynthetic oxygen evolution, must be modified to include a molecule of bicarbonate in addition to one molecule of water which in turn must be incorporated into the cycle instead of two water molecules. Furthermore, this study provides a theoretical basis for constructing a newer artificial photosynthetic reactor coupling light reactions with the dark reactions.


Assuntos
Bicarbonatos , Chlamydomonas reinhardtii , Isótopos de Oxigênio , Fotossíntese , Água , Bicarbonatos/química , Bicarbonatos/metabolismo , Água/química , Água/metabolismo , Isótopos de Oxigênio/química , Chlamydomonas reinhardtii/metabolismo , Microcystis/metabolismo , Oxigênio/metabolismo , Oxigênio/química , Dióxido de Carbono/metabolismo , Dióxido de Carbono/química
11.
Waste Manag ; 182: 21-31, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38631177

RESUMO

This research investigates the formation mechanism of soot and particulate matter during the pyrolysis and gasification of waste derived from Municipal Solid Waste (MSW) in a laboratory scale drop tube furnace. Compared with CO2 gasification atmosphere, more ultrafine particles (PM0.2, aerodynamic diameter less than 0.2 µm) were generated in N2 atmosphere at 1200℃, which were mainly composed of polycyclic aromatic hydrocarbons (PAHs), graphitic carbonaceous soot and volatile alkali salts. High reaction temperatures promote the formation of hydrocarbon gaseous products and their conversion to PAHs, which ultimately leads to the formation of soot particles. The soot particles generated by waste derived from MSW pyrolysis and gasification both have high specific surface area and well-developed pore structure. Compared with pyrolysis, the soot generated by gasification of waste derived from MSW had smaller size and higher proportion of inorganic components. The higher pyrolysis temperature led to the collapse of the mesoporous structure of submicron particles, resulting in a decrease in total pore volume and an increase in specific surface area. Innovatively, this research provides an explanation for the effect of reaction temperature/ CO2 on the formation pathways and physicochemical properties of soot and fine particulate matter.


Assuntos
Temperatura Alta , Material Particulado , Pirólise , Resíduos Sólidos , Fuligem , Material Particulado/análise , Material Particulado/química , Resíduos Sólidos/análise , Fuligem/análise , Fuligem/química , Eliminação de Resíduos/métodos , Incineração/métodos , Dióxido de Carbono/análise , Dióxido de Carbono/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/química , Tamanho da Partícula
12.
Nanotechnology ; 35(31)2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38631327

RESUMO

Clean room facilities are becoming more popular in both academic and industry settings, including low-and middle-income countries. This has led to an increased demand for cost-effective gas sensors to monitor air quality. Here we have developed a gas sensor using CoNiO2nanoparticles through combustion method. The sensitivity and selectivity of the sensor towards CO2were influenced by the structure of the nanoparticles, which were affected by the reducing agent (biofuels) used during synthesis. Among all reducing agents, urea found to yield highly crystalline and uniformly distributed CoNiO2nanoparticles, which when developed into sensors showed high sensitivity and selectivity for the detection of CO2gas in the presence of common interfering volatile organic compounds observed in cleanroom facilities including ammonia, formaldehyde, acetone, toluene, ethanol, isopropanol and methanol. In addition, the urea-mediated nanoparticle-based sensors exhibited room temperature operation, high stability, prompt response and recovery rates, and excellent reproducibility. Consequently, the synthesis approach to nanoparticle-based, energy efficient and affordable sensors represent a benchmark for CO2sensing in cleanroom settings.


Assuntos
Dióxido de Carbono , Nanopartículas , Ureia , Dióxido de Carbono/análise , Dióxido de Carbono/química , Ureia/análise , Nanopartículas/química , Compostos Orgânicos Voláteis/análise , Dióxido de Silício/química , Reprodutibilidade dos Testes
13.
Environ Sci Technol ; 58(19): 8313-8325, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38689207

RESUMO

CO2 is 45 to 50 times more concentrated in soil than in air, resulting in global diffusive fluxes that outpace fossil fuel combustion by an order of magnitude. Despite the scale of soil CO2 emissions, soil-based climate change mitigation strategies are underdeveloped. Existing approaches, such as enhanced weathering and sustainable land management, show promise but continue to face deployment barriers. We introduce an alternative approach: the use of solid adsorbents to directly capture CO2 in soils. Biomass-derived adsorbents could exploit favorable soil CO2 adsorption thermodynamics while also sequestering solid carbon. Despite this potential, previous study of porous carbon CO2 adsorption is mostly limited to single-component measurements and conditions irrelevant to soil. Here, we probe sorption under simplified soil conditions (0.2 to 3% CO2 in balance air at ambient temperature and pressure) and provide physical and chemical characterization data to correlate material properties to sorption performance. We show that minimally engineered pyrogenic carbons exhibit CO2 sorption capacities comparable to or greater than those of advanced sorbent materials. Compared to textural features, sorbent carbon bond morphology substantially influences low-pressure CO2 adsorption. Our findings enhance understanding of gas adsorption on porous carbons and inform the development of effective soil-based climate change mitigation approaches.


Assuntos
Dióxido de Carbono , Carbono , Solo , Dióxido de Carbono/química , Solo/química , Porosidade , Adsorção , Carbono/química , Carvão Vegetal/química , Mudança Climática
14.
Int J Biol Macromol ; 268(Pt 1): 131659, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38641275

RESUMO

As the most abundant natural homo-polymer, cellulose has the potential to enhance polymer properties reducing the cost of raw materials. In this work, the carboxylate cellulose nanofiber (CNF-C) was selected to modify polylactic acid (PLA) foams, and the density functional theory was constructed to help analyze the foaming mechanism quantitatively. The theoretical results showed that the ordered structure, the carboxyl and the hydroxyl of CNF-C were more conducive to providing much stronger CO2 adsorption for bubble nucleation, where the predicted critical bubble size decreased and the cell density increased with the addition of CNF-C. The experimental results revealed that the CNF-C promoted the rheological properties and crystallization behaviors of PLA samples, the PLA/CNF-C foams were characterized with uniform structures, the average cell size decreased from 21.39 µm to 0.19 µm, and the cell number density increased from 2.65×1010cell/cm3 to 2.30×1014cell/cm3. Those improvements resulted in an increase of 394.0 % for the compressive strength of the prepared foams. Generally, the high-performance PLA/CNF-C foams were fabricated successfully without compromising the properties of bio-based and biodegradable, the foaming mechanism was analyzed combining theoretical results with experimental data, and it was believed to provide a guide for cellulose reinforcing biodegradable polymer materials.


Assuntos
Celulose , Nanofibras , Poliésteres , Celulose/química , Poliésteres/química , Nanofibras/química , Reologia , Dióxido de Carbono/química , Propriedades de Superfície , Cristalização , Adsorção
15.
J Environ Manage ; 359: 120782, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38669884

RESUMO

Capturing CO2 using clamshell/eggshell-derived CaO adsorbent can not only reduce carbon emissions but also alleviate the impact of trash on the environment. However, organic acid was usually used, high-temperature calcination was often performed, and CO2 was inevitably released during preparing CaO adsorbents from shell wastes. In this work, CaO-based CO2 adsorbent was greenly prepared by calcium-induced hydrogenation of clamshell and eggshell wastes in one pot at room/moderate temperature. CO2 adsorption experiments were performed in a thermogravimetric analyzer (TGA). The adsorption performance of the adsorbents obtained from the mechanochemical reaction (BM-C/E-CaO) was superior to that of the adsorbents obtained from the thermochemical reaction (Cal-C/E-CaO). The CO2 adsorption capacity of BM-C-CaO at 650 °C is up to 36.82 wt%, but the adsorption decay rate of the sample after 20 carbonation/calcination cycles is only 30.17%. This study offers an alternative energy-saving method for greenly preparing CaO-based adsorbent from shell wastes.


Assuntos
Cálcio , Dióxido de Carbono , Dióxido de Carbono/química , Adsorção , Cálcio/química , Hidrogenação , Temperatura , Compostos de Cálcio/química , Óxidos/química
16.
Chemosphere ; 358: 142157, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38679181

RESUMO

Microbial electrosynthesis (MES) is an electrically driven technology that can be used for converting CO/CO2 into chemicals. The unique electronic and substrate properties of CO make it an important research target for MES. However, CO can poison the cathode and increase the overpotential of hydrogen evolution reaction (HER), thus reducing the electron transfer rate via H2. This work evaluated the effect of an anti-CO HER catalyst on the performance of MES for CO/CO2 conversion. ZnMo-metal-organic framework (MOF) materials with different calcination temperatures were synthesized. ZnMo-MOF-800 with Mo2C nanoparticles as active centers exhibited excellent resistance to CO toxicity. It also obtained the highest hydrogen evolution and enhanced electron transfer rate in CO atmosphere. MES with ZnMo-MOF-800 cathode and Clostridium ljungdahlii as biocatalyst obtained 0.31 g L-1 d-1 acetate yield, 0.1 g L-1 d-1 butyrate yield, and 0.09 g L-1 d-1 2,3-butanediol yield in CO/CO2, while Pt/C only get 0.076 g L-1 d-1 acetate yield, 0.05 g L-1 d-1 butyrate yield and 0.02 g L-1 d-1 2,3-butanediol yield. ZnMo-MOF-800 was conducive to biofilm formation, enabling it to better resist CO toxicity. This work provides new opportunities for constructing a highly efficient cathode with an anti-CO hydrogen evolution catalyst to enhance CO/CO2 conversion in MES.


Assuntos
Dióxido de Carbono , Monóxido de Carbono , Hidrogênio , Estruturas Metalorgânicas , Hidrogênio/metabolismo , Hidrogênio/química , Dióxido de Carbono/química , Catálise , Estruturas Metalorgânicas/química , Eletrodos , Clostridium/metabolismo , Técnicas Eletroquímicas , Molibdênio/química , Zinco/química
17.
Methods Mol Biol ; 2790: 63-76, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38649566

RESUMO

Stomata can be distributed exclusively on the abaxial or adaxial leaf surface, but they are most commonly found on both leaf surfaces. Variations in stomatal arrangement, patterning, and the impact on photosynthesis can be measured using an infrared gas exchange system. However, when using standard gas exchange techniques, both surfaces are measured together and averaged to provide leaf-level values. Employing an innovative gas exchange apparatus with two infrared gas analyzers, separate gaseous flux from both leaf surfaces can be quantified simultaneously and independently. Here, we provide examples of typical measurements that can be performed using a "split chamber" gas exchange system.


Assuntos
Fotossíntese , Estômatos de Plantas , Estômatos de Plantas/metabolismo , Estômatos de Plantas/fisiologia , Gases/química , Folhas de Planta/metabolismo , Dióxido de Carbono/metabolismo , Dióxido de Carbono/análise , Dióxido de Carbono/química
18.
J Chromatogr A ; 1722: 464869, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38604057

RESUMO

Hydrodynamics, efficiency, and loading capacity of two semi-packed columns with different cross sections (NANO 315 µm x 18 µm; CAP 1000 µm x 28 µm) and similar pillar diameter and pillar-pillar distance (respectively 5 µm and 2.5 µm) have been compared in high-pressure gas chromatography. A flow prediction tool has been first designed to determine pressure variations and hold-up time across the chromatographic system taking into account the rectangular geometry of the ducts into the semi-packed columns. Intrinsic values of Height Equivalent to Theoretical Plate were determined for NANO and CAP columns using helium as carrier gas and similar values have been obtained (30 µm) for the two columns. Loading capacity of semi-packed columns were determined for decane at 70 °C using helium, and the highest value was obtained from CAP column (larger cross section and stationary phase content). Finally, significant HETP improvement (down to 15 µm) and peak shape were observed when carbon dioxide was used as carrier gas, suggesting mobile phase adsorption on stationary phase in high pressure conditions.


Assuntos
Hélio , Pressão , Cromatografia Gasosa/métodos , Cromatografia Gasosa/instrumentação , Hélio/química , Hidrodinâmica , Dióxido de Carbono/química , Adsorção
19.
Waste Manag ; 181: 11-19, 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38574688

RESUMO

Mattresses are a difficult waste to manage in landfills due to their large volume and low density. Pyrolysis treatment could reduce its volume while producing fuel or products valuable for the chemical industry. Pressurized pyrolysis at 400, 450, and 500 °C is carried out in a lab-scale autoclave at initial pressures 4.2, 8.4, and 16.8 bar. Product gas yield increases slightly along with elevated pressure as well as temperature. However, beyond 8.4 bar the initial pressure makes no discernible differences. CO and CO2 are the major gas species followed by CH4. CO contributes the most to the product gas energy content followed by C3 species, C2H6, and H2. Calculated energy content (heating value) is between 2 and 15 MJ·Nm-3. In terms of product gas energy content, low pressure pyrolysis is favorable over high pressure pyrolysis. According to integration areas of chromatographic measurements the liquid phase contains up to 25 % of N-compounds, with benzonitrile being the most abundant, followed by toluene, o-xylene, and ethylbenzene. The solid char maintains constant properties across operating conditions, with carbon and energy contents of approximately 75 wt% and 30 MJ·kg-1, respectively.


Assuntos
Pirólise , Instalações de Eliminação de Resíduos , Eliminação de Resíduos/métodos , Pressão , Gerenciamento de Resíduos/métodos , Metano/análise , Metano/química , Dióxido de Carbono/análise , Dióxido de Carbono/química
20.
Waste Manag ; 181: 199-210, 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38643515

RESUMO

Supercritical CO2 (scCO2) extraction assisted by complexing copolymers is a promising process to recover valuable metals from lithium-ion batteries (LIBs). CO2, in addition to being non-toxic, abundant and non-flammable, allows an easy separation of metal-complexes from the extraction medium by depressurization, limiting the wastewater production. In this study, CO2-philic gradient copolymers bearing phosphonic diacid complexing groups (poly(vinylbenzylphosphonic diacid-co-1,1,2,2-tetrahydroperfluorodecylacrylate), p(VBPDA-co-FDA)) were synthesized for the extraction of lithium and cobalt from LiCoO2 cathode material. Notably, the copolymer was able to play the triple role of leaching agent, complexing agent and surfactant. The proof of concept for leaching, complexation and extraction was achieved, using two different extraction systems. A first extraction system used aqueous hydrogen peroxide as reducing agent while it was replaced by ethanol in the second extraction system. The scCO2 extraction conditions such as extraction time, temperature, functional copolymer concentration, and the presence of additives were optimized to improve the metals extraction from LiCoO2 cathode material, leading to an extraction efficiency of Li and Co up to ca. 75 % at 60 °C and 250 bar.


Assuntos
Dióxido de Carbono , Cobalto , Lítio , Polímeros , Cobalto/química , Cobalto/isolamento & purificação , Lítio/química , Dióxido de Carbono/química , Polímeros/química , Óxidos/química , Reciclagem/métodos , Eletrodos , Fontes de Energia Elétrica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA