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1.
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
2.
Compr Rev Food Sci Food Saf ; 23(3): e13345, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38638070

RESUMO

Supercritical carbon dioxide (SC-CO2) has emerged as a nonthermal technology to guarantee food safety. This review addresses the potential of SC-CO2 technology in food preservation, discussing the microbial inactivation mechanisms and the impact on food products' quality parameters and bioactive compounds. Furthermore, the main advantages and gaps are denoted. SC-CO2 technology application causes adequate microbial reductions (>5 log cfu/mL) of spoilage and pathogenic microorganisms, enzyme inactivation, and improvements in the storage stability in fruit and vegetable products (mainly fruit juices), meat products, and dairy derivatives. SC-CO2-treated products maintain the physicochemical, technological, and sensory properties, bioactive compound concentrations, and biological activity (antioxidant and angiotensin-converting enzyme-inhibitory activities) similar to the untreated products. The optimization of processing parameters (temperature, pressure, CO2 volume, and processing times) is mandatory for achieving the desired results. Further studies should consider the expansion to different food matrices, shelf-life evaluation, bioaccessibility of bioactive compounds, and in vitro and in vivo studies to prove the benefits of using SC-CO2 technology. Moreover, the impact on sensory characteristics and, mainly, the consumer perception of SC-CO2-treated foods need to be elucidated. We highlight the opportunity for studies in postbiotic production. In conclusion, SC-CO2 technology may be used for microbial inactivation to ensure food safety without losing the quality parameters.


Assuntos
Dióxido de Carbono , Compreensão , Viabilidade Microbiana , Dióxido de Carbono/química , Dióxido de Carbono/farmacologia , Contagem de Colônia Microbiana , Manipulação de Alimentos/métodos
3.
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
4.
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
5.
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
6.
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
7.
Nat Commun ; 15(1): 2592, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38519475

RESUMO

Carbon isotope labelling of bioactive molecules is essential for accessing the pharmacokinetic and pharmacodynamic properties of new drug entities. Aryl carboxylic acids represent an important class of structural motifs ubiquitous in pharmaceutically active molecules and are ideal targets for the installation of a radioactive tag employing isotopically labelled CO2. However, direct isotope incorporation via the reported catalytic reductive carboxylation (CRC) of aryl electrophiles relies on excess CO2, which is incompatible with carbon-14 isotope incorporation. Furthermore, the application of some CRC reactions for late-stage carboxylation is limited because of the low tolerance of molecular complexity by the catalysts. Herein, we report the development of a practical and affordable Pd-catalysed electrocarboxylation setup. This approach enables the use of near-stoichiometric 14CO2 generated from the primary carbon-14 source Ba14CO3, facilitating late-stage and single-step carbon-14 labelling of pharmaceuticals and representative precursors. The proposed isotope-labelling protocol holds significant promise for immediate impact on drug development programmes.


Assuntos
Carbono , Paládio , Carbono/química , Isótopos de Carbono , Radioisótopos de Carbono , Paládio/química , Marcação por Isótopo/métodos , Dióxido de Carbono/química , Catálise
8.
J Environ Manage ; 355: 120447, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38460326

RESUMO

This research explicitly investigates the utilization of Chlorella Vulgaris sp. microalgae as a renewable source for lipid production, focusing on its application in bioplastic manufacturing. This study employed the supercritical fluid extraction technique employing supercritical CO2 (sCO2) as a green technology to selectively extract and produce PHA's precursor utilizing CO2 solvent as a cleaner solvent compared to conventional extraction method. The study assessed the effects of three extraction parameters, namely temperature (40-60 °C), pressure (15-35 MPa), and solvent flow rate (4-8 ml/min). The pressure, flowrate, and temperature were found to be the most significant parameters affecting the sCO2 extraction. Through Taguchi optimization, the optimal parameters were determined as 60 °C, 35 MPa, and 4 ml/min with the highest lipid yield of 46.74 wt%; above-average findings were reported. Furthermore, the pretreatment process involved significant effects such as crumpled and exhaustive structure, facilitating the efficient extraction of total lipids from the microalgae matrix. This study investigated the microstructure of microalgae biomatrix before and after extraction using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Fourier-transform infrared spectroscopy (FTIR) was utilized to assess the potential of the extracted material as a precursor for biodegradable plastic production, with a focus on reduced heavy metal content through inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The lipid extracted from Chlorella Vulgaris sp. microalgae was analysed using gas chromatography-mass spectrometry (GC-MS), identifying key constituents, including oleic acid (C18H34O2), n-Hexadecanoic acid (C16H32O2), and octadecanoic acid (C18H36O2), essential for polyhydroxyalkanoate (PHA) formation.


Assuntos
Chlorella vulgaris , Microalgas , Poli-Hidroxialcanoatos , Chlorella vulgaris/química , Microalgas/química , Dióxido de Carbono/química , Solventes/química , Biomassa
9.
Waste Manag ; 178: 331-338, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38430747

RESUMO

The combination of microbial electrolytic cells and anaerobic digestion (MEC-AD) became an efficient method to improve CO2 capture for waste sludge treatment. By adding CaCl2 and wollastonite, the CO2 sequestration effect with mineral carbonation under 0 V and 0.8 V was studied. The results showed that applied voltage could increase dissolved chemical oxygen demand (SCOD) degradation efficiency and biogas yield effectively. In addition, wollastonite and CaCl2 exhibited different CO2 sequestration performances due to different Ca2+ release characteristics. Wollastonite appeared to have a better CO2 sequestration effect and provided a wide margin of pH change, but CaCl2 released Ca2+ directly and decreased the pH of the MEC-AD system. The results showed methane yield reached 137.31 and 163.50 mL/g SCOD degraded and CO2 content of biogas is only 12.40 % and 2.22 % under 0.8 V with CaCl2 and wollastonite addition, respectively. Finally, the contribution of chemical CO2 sequestration by mineral carbonation and biological CO2 sequestration by hydrogenotrophic methanogenesis was clarified with CaCl2 addition. The chemical and biological CO2 sequestration percentages were 46.79 % and 53.21 % under 0.8 V, respectively. With the increased applied voltage, the contribution of chemical CO2 sequestration rose accordingly. The findings in this study are of great significance for further comprehending the mechanism of calcium addition on CO2 sequestration in the MEC-AD system and providing guidance for the later engineering application.


Assuntos
Compostos de Cálcio , Dióxido de Carbono , Esgotos , Silicatos , Dióxido de Carbono/química , Anaerobiose , Biocombustíveis , Cloreto de Cálcio , Minerais , Carbonatos , Metano , Reatores Biológicos
10.
Sci Total Environ ; 923: 171384, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38432383

RESUMO

Some methanogens are electrotrophic bio-corroding microbes that can acquire electrons from solid surfaces including metals. In the laboratory, pure cultures of methanogenic cells oxidize iron-based materials including carbon steel, stainless steel, and Fe0. For buried or immersed pipelines or other metallic structures, methanogens are often major components of corroding biofilms with complex interspecies relationships. Models explaining how these microbes acquire electrons from solid donors are multifaceted and include electron transfer via redox mediators such as H2 or by direct contact through membrane proteins. Understanding the electron uptake (EU) routes employed by corroding methanogens is essential to develop efficient strategies for corrosion prevention. It is also beneficial for the development of bioenergy applications relying on methanogenic EU from solid donors such as bioelectromethanogenesis, hybrid photosynthesis, and the acceleration of anaerobic digestion with electroconductive particles. Many methanogenic species carrying out biocorrosion are the same ones forming the extensive abiotic-biological interfaces at the core of these bio-applications. This review will discuss the interactions between corrosive methanogens and metals and how the EU capability of these microbes can be harnessed for different sustainable biotechnologies.


Assuntos
Dióxido de Carbono , Elétrons , Dióxido de Carbono/química , Metais , Oxirredução , Transporte de Elétrons , Corrosão
11.
J Environ Radioact ; 275: 107425, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38554648

RESUMO

As the need for global decommissioning and site remediation of aging and shut-down nuclear power plants continues to grow, it becomes increasingly crucial to efficiently treat contaminated soil while minimizing waste generation. This study explores an innovative soil decontamination approach that utilizes supercritical carbon dioxide (SCCO2) as the primary solvent, along with ethanol as a co-solvent and specific additives, including a chelate ligand (catechol ligand) and a co-ligand (NEt4PFOSA). The advantages of SCCO2, such as its penetration and solubility, coupled with its ability to separate from radioactive waste, are harnessed in this research. The study demonstrates that the combination of SCCO2, ethanol, and additives significantly enhances decontamination efficiency, particularly for cesium (Cs), strontium (Sr), and uranium (U) contamination. Results indicate that decontamination efficiency varies with soil particle size, with smaller particles presenting greater challenges. This study presents a promising eco-friendly soil decontamination technology using SCCO2 containing ethanol and specific additives to efficiently reduce radioactive contamination in soil.


Assuntos
Dióxido de Carbono , Descontaminação , Etanol , Poluentes Radioativos do Solo , Descontaminação/métodos , Poluentes Radioativos do Solo/análise , Etanol/química , Dióxido de Carbono/química , Recuperação e Remediação Ambiental/métodos , Radioisótopos de Césio/química , Solo/química
12.
Environ Sci Technol ; 58(8): 3747-3754, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38302413

RESUMO

Basalt formations are promising candidates for the geologic storage of anthropogenic CO2 due to their storage capacity, porosity, permeability, and reactive geochemical trapping ability. The Wallula Basalt Carbon Storage Pilot Project demonstrated that supercritical CO2 injected into >800 m deep Columbia River Basalt Group stacked reservoir flow tops mineralizes to ankerite-siderite-aragonite on month-year time scales, with 60% of the 977 metric tons of CO2 converted within 2 years. The potential impacts of mineral precipitation and consequent changes in the rock porosity, pore structure, pore size, and pore size distributions have likely been underestimated hitherto. Herein, we address these knowledge gaps using X-ray microcomputed tomography (XMT) to evaluate the pore network architecture of sidewall cores recovered 2 years after CO2 injection. In this study, we performed a detailed quantitative analysis of the CO2-reacted basalt cores by XMT imaging. Reconstructed 3D images were analyzed to determine the distribution and volumetric details of porosity and anthropogenic carbonate nodules in the cores. Additional mineralogic quantification provided insight into the overall paragenesis and carbonate growth mechanisms, including mineralogic/chemical zonation. These findings are being used to parametrize multiphase reactive transport models to predict the fate and transport of subsurface CO2, enabling scale-up to commercial-scale geologic carbon storage in basalts and other reactive mafic-ultramafic formations.


Assuntos
Dióxido de Carbono , Carbono , Silicatos , Microtomografia por Raio-X , Dióxido de Carbono/química , Projetos Piloto , Carbonatos
13.
PLoS One ; 19(2): e0292593, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38329978

RESUMO

A previously undocumented shallow water hydrothermal field from Sicily (Southern Tyrrhenian Sea, Italy) is here described, based on a multidisciplinary investigation. The field, covering an area of nearly 8000 m2 and a depth from the surface to -5 m, was explored in June 2021 to characterise the main physico-chemical features of the water column, describe the bottom topography and features, and identify the main megabenthic and nektonic species. Twenty sites were investigated to characterise the carbonate system. Values of pH ranged between 7.84 and 8.04, ΩCa between 3.68 and 5.24 and ΩAr from 2.41 to 3.44. Geochemical analyses of hydrothermal gases revealed a dominance of CO2 (98.1%) together with small amounts of oxygen and reactive gases. Helium isotope ratios (R/Ra = 2.51) and δ13CCO2 suggest an inorganic origin of hydrothermal degassing of CO2 and the ascent of heat and deep-seated magmatic fluids to the surface. Visual census of fishes and megabenthos (mainly sessile organisms) allowed the identification of 64 species, four of which are protected by the SPA/BIO Protocol and two by the International Union for Conservation of Nature. The macroalgae Halopteris scoparia and Jania rubens and the sponge Sarcotragus sp. were the dominant taxa in the area, while among fishes Coris julis and Chromis chromis were the most abundant species. This preliminary investigation of San Giorgio vent field suggests that the site could be of interest and suitable for future experimental studies of ocean acidification.


Assuntos
Fontes Hidrotermais , Água do Mar , Mar Mediterrâneo , Água do Mar/química , Dióxido de Carbono/química , Concentração de Íons de Hidrogênio , Acidificação dos Oceanos , Água , Sicília
14.
J Environ Sci (China) ; 140: 219-229, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38331502

RESUMO

This work shows the synthesis, characterization and evaluation of dense-ceramic membranes made of Ce0.85Gd0.15O2-δ-LaNiO3 (CG-LN) composites, where the fluorite-perovskite ratio (CG:LN) was varied as follows: 75:25, 80:20 and 85:15 wt.%. Supports were initially characterized by XRD, SEM and electrical conductivity (using vacuum and oxygen atmospheres), to determine the composition, microstructural and ionic-electronic conductivity properties. Later, supports were infiltrated with an eutectic carbonates mixture, producing the corresponding dense dual-phase membranes, in which CO2 permeation tests were conducted. Here, CO2 permeation experiments were performed from 900 to 700°C, in the presence and absence of oxygen (flowed in the sweep membrane side). Results showed that these composites possess high CO2 permeation properties, where the O2 addition significantly improves the ionic conduction on the sweep membrane side. Specifically, the GC80-LN20 composition presented the best results due to the following physicochemical characteristics: high electronic and ionic conductivity, appropriate porosity, interconnected porous channels, as well as thermal and chemical stabilities between the composite support and carbonate phases.


Assuntos
Dióxido de Carbono , Oxigênio , Dióxido de Carbono/química , Oxigênio/química , Carbonatos/química , Cerâmica/química
15.
J Environ Sci (China) ; 140: 113-122, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38331493

RESUMO

Carbon dioxide capture and reduction (CCR) process emerges as an efficient catalytic strategy for CO2 capture and conversion to valuable chemicals. K-promoted Cu/Al2O3 catalysts exhibited promising CO2 capture efficiency and highly selective conversion to syngas (CO + H2). The dynamic nature of the Cu-K system at reaction conditions complicates the identification of the catalytically active phase and surface sites. The present work aims at more precise understanding of the roles of the potassium and copper and the contribution of the metal oxide support. While γ-Al2O3 guarantees high dispersion and destabilisation of the potassium phase, potassium and copper act synergistically to remove CO2 from diluted streams and promote fast regeneration of the active phase for CO2 capture releasing CO while passing H2. A temperature of 350℃ is found necessary to activate H2 dissociation and generate the active sites for CO2 capture. The effects of synthesis parameters on the CCR activity are also described by combination of ex-situ characterisation of the materials and catalytic testing.


Assuntos
Cobre , Potássio , Cobre/toxicidade , Cobre/química , Dióxido de Carbono/química , Óxidos , Catálise
16.
J Environ Sci (China) ; 140: 12-23, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38331494

RESUMO

The increasing anthropogenic emissions of greenhouse gases (GHG) is encouraging extensive research in CO2 utilisation. Dry reforming of methane (DRM) depicts a viable strategy to convert both CO2 and CH4 into syngas, a worthwhile chemical intermediate. Among the different active phases for DRM, the use of nickel as catalyst is economically favourable, but typically deactivates due to sintering and carbon deposition. The stabilisation of Ni at different loadings in cerium zirconate inorganic complex structures is investigated in this work as strategy to develop robust Ni-based DRM catalysts. XRD and TPR-H2 analyses confirmed the existence of different phases according to the Ni loading in these materials. Besides, superficial Ni is observed as well as the existence of a CeNiO3 perovskite structure. The catalytic activity was tested, proving that 10 wt.% Ni loading is the optimum which maximises conversion. This catalyst was also tested in long-term stability experiments at 600 and 800°C in order to study the potential deactivation issues at two different temperatures. At 600°C, carbon formation is the main cause of catalytic deactivation, whereas a robust stability is shown at 800°C, observing no sintering of the active phase evidencing the success of this strategy rendering a new family of economically appealing CO2 and biogas mixtures upgrading catalysts.


Assuntos
Cério , Níquel , Níquel/química , Dióxido de Carbono/química , Metano/química , Cério/química , Carbono
17.
J Environ Sci (China) ; 140: 230-241, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38331503

RESUMO

Cigarette butts (CBs) are one of the most common types of litter in the world. Due to the toxic substances they contain, the waste generated poses a harmful risk to the environment, and therefore there is an urgent need for alternative solutions to landfill storage. Thus, this work presents a possible revalorization of this waste material, which implies interesting environmental benefits. CBs were used as sacrificial templates for the preparation of CaO-based materials by impregnation with calcium and magnesium nitrates followed by flaming combustion. These materials presented enhanced porosity for their use in the Calcium Looping process applied either to thermochemical energy storage or CO2 capture applications. The influence of the concentration of Ca and Mg in the impregnating solutions on the multicycle reactivity of the samples was studied. An improved multicycle performance was obtained in terms of conversion for both applications.


Assuntos
Dióxido de Carbono , Produtos do Tabaco , Dióxido de Carbono/química , Cálcio , Resíduos , Fenômenos Físicos
18.
Environ Sci Pollut Res Int ; 31(12): 18765-18784, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38349490

RESUMO

In this study, an experimental strategy to obtain biochar and activated carbon from torrefied palm kernel shell as an efficient material for CO2 removal was evaluated. Biochar was obtained by slow pyrolysis of palm kernel shell at different temperatures (350 °C, 550 °C, and 700 °C) and previously torrefied palm kernel shell at different temperatures (220 °C, 250 °C, and 280 °C). Subsequently, activated carbons were prepared by physical activation with CO2 from previously obtained biochar samples. The CO2 adsorption capacity was measured using TGA. The experimental results showed that there is a correlation between the change in the O/C and H/C ratios and the functional groups -OH and C=O observed via FTIR in the obtained char, indicating that both dehydration and deoxygenation reactions occur during torrefaction; this favors the deoxygenation reactions and makes them faster through CO2 liberation during the pyrolysis process. The microporous surface area shows a significant increase with higher pyrolysis temperatures, as a product of the continuous carbonization reactions, allowing more active sites for CO2 removal. Pyrolysis temperature is a key factor in CO2 adsorption capacity, leading to a CO2 adsorption capacity of up to 75 mg/gCO2 for biochar obtained at 700 °C from non-torrefied palm kernel shell (Char700). Activated carbon obtained from torrefied palm kernel shell at 280 °C (T280-CHAR700-AC) exhibited the highest CO2 adsorption capacity (101.9 mg/gCO2). Oxygen-containing functional groups have a direct impact on CO2 adsorption performance due to electron interactions between CO2 and these functional groups. These findings could provide a new experimental approach for obtaining optimal adsorbent materials exclusively derived from thermochemical conversion processes.


Assuntos
Dióxido de Carbono , Carvão Vegetal , Carvão Vegetal/química , Dióxido de Carbono/química , Temperatura Alta , Temperatura , Adsorção
19.
Mol Pharm ; 21(3): 1233-1245, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38350108

RESUMO

Carbon dioxide radical anion (•CO2-) is a powerful reducing agent that can reduce protein disulfide bonds and convert molecular oxygen to superoxide. Therefore, the generation of •CO2- can be detrimental to pharmaceutical formulations. Iron is among the most prevalent impurities in formulations, where Fe(III) chelates of histidine (His) can produce •CO2- upon exposure to near-UV light (Zhang and Schöneich, Eur. J. Pharm. Biopharm. 2023, 190, 231-241). Here, we monitor by spin-trapping in combination with electron paramagnetic resonance spectroscopy and/or high-performance liquid chromatography-mass spectrometry analysis the photochemical formation of •CO2- for a series of common amino acid excipients, including arginine (Arg), methionine (Met), proline (Pro), glutamic acid (Glu), glycine (Gly), aspartic acid (Asp), and lysine (Lys). Our results indicate that in the presence of Fe(III), Asp, and Glu produce significant yields of •CO2- under photoirradiation with near-UV light. Notably, Asp demonstrates the highest efficiency of •CO2- generation compared with that of the other amino acid excipients. Stable isotope labeling indicates that •CO2- exclusively originates from the α-carboxyl group of Asp. Mechanistic studies reveal two possible pathways for •CO2- formation, which involve either a ß-carboxyl radical or an amino radical cation intermediate.


Assuntos
Aminoácidos , Ácido Aspártico , Raios Ultravioleta , Dióxido de Carbono/química , Excipientes , Compostos Férricos , Fotólise , Processos Fotoquímicos , Ácido Glutâmico , Superóxidos
20.
Environ Sci Pollut Res Int ; 31(11): 16309-16327, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38315341

RESUMO

Climate change caused by the greenhouse gases CO2 remains a topic of global concern. To mitigate the excessive levels of anthrophonic CO2 in the atmosphere, CO2 capture methods have been developed and among these, adsorption is an especially promising method. This paper presents a series of amine functionalized biochar obtained from desiccated coconut waste (amine-biochar@DCW) for use as CO2 adsorbent. They are ethylenediamine-functionalized biochar@DCW (EDA-biochar@DCW), diethylenetriamine-functionalized biochar@DCW (DETA-biochar@DCW), triethylenetetramine-functionalized biochar@DCW (TETA-biochar@DCW), tetraethylenepentamine-functionalized biochar@DCW (TEPA-biochar@DCW), and pentaethylenehexamine-functionalized biochar@DCW (PEHA-biochar@DCW). The adsorbents were obtained through amine functionalization of biochar and they are characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Brunauer-Emmett-Teller (BET), and thermogravimetric analysis (TGA). The CO2 adsorption study was conducted isothermally and using a thermogravimetric analyzer. From the results of the characterization analyses, a series of amine-biochar@DCW adsorbents had larger specific surface area in the range of 16.2 m2/g-37.1 m2/g as compare to surface area of pristine DCW (1.34 m2/g). Furthermore, the results showed an increase in C and N contents as well as the appearance of NH stretching, NH bending, CN stretching, and CN bending, suggesting the presence of amine on the surface of biochar@DCW. The CO2 adsorption experiment shows that among the amine modified biochar adsorbents, TETA-biochar@DCW has the highest CO2 adsorption capacity (61.78 mg/g) when using a mass ratio (m:m) of biochar@DCW:TETA (1:2). The adsorption kinetics on the TETA-biochar@DCW was best fitted by the pseudo-second model (R2 = 0.9998), suggesting the adsorption process occurs through chemisorption. Additionally, TETA-biochar@DCW was found to have high selectivity toward CO2 gas and good reusability even after five CO2 adsorption-desorption cycles. The results demonstrate the potential of novel CO2 adsorbents based on amine functionalized on desiccated coconut waste biochar.


Assuntos
Dióxido de Carbono , Cocos , Dióxido de Carbono/química , Porosidade , Carvão Vegetal , Espectroscopia de Infravermelho com Transformada de Fourier , Trientina , Adsorção , Cinética
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