The process of carbonaceous materials gasification is especially relevant in Russia, where the volume of coal waste exceeds 120 million tons. A gasification installation for carbon-containing waste operating in the fixed-bed mode has been developed. Experiments on gasification of fine coal fraction samples (1–2 mm) were carried out using preheated air, a steam-air mixture, and air with added carbon dioxide as gasifying agents. The work used the methods of differential scanning calorimetry, thermogravimetric analysis, and chromatographic analysis. Additions of water vapor and carbon dioxide made it possible to increase the heat of combustion and increase the gasification efficiency to 54%. The operating mode of the gas generator was determined, ensuring the production of synthesis gas with a calorific value of 3.6 MJ/nm3. It is shown that the highest efficiency of gas generation is achieved in the steam-air gasification mode with the addition of water vapor in the amount of 0.1 kg per 1 kg of coal and with the use of air as a gasifying agent with the addition of carbon dioxide in a volume ratio of 100:5. It is established that an increase in the addition of water vapor and carbon dioxide above the optimal amounts leads to a decrease in the efficiency of the gasification process. The process can use waste from various industries, including oil sludge, which determines its significance for the effective management of carbon-containing waste and for achieving broader environmental and economic goals.

Objectives: This study aimed to evaluate whether the addition of pressurized carbon dioxide (PCD) influences the antimicrobial efficacy of 2.5% sodium hypochlorite (NaOCl) against Enterococcus faecalis biofilm in root canals and dentinal tubules. Methods: Forty extracted human mandibular premolars with single canals were contaminated with E. faecalis for 10 days and randomly assigned to four groups (n = 10): 2.5% NaOCl, 2.5% NaOCl + CO2, sterile saline, and sterile saline + CO2. The pH and temperature of the NaOCl solution were measured before and after CO2 incorporation. Microbial load was assessed by CFU counts before and after irrigation, and in dentin samples from the cervical, middle, and apical thirds. Oxidative stress was evaluated via lipid peroxidation (TBARS), protein carbonyl content, and total protein quantification. Biofilm metabolic activity was analyzed using the XTT reduction assay. Data were analyzed using one-way ANOVA on ranks and two-way repeated measures ANOVA (α = 0.05), a very large effect size (Cohen’s d) ≈ 1.756 was assumed. Results: All irrigation protocols significantly reduced bacterial load (p < 0.05). Both NaOCl groups outperformed the saline controls (p = 0.009). The addition of CO2 to NaOCl slightly enhanced disinfection in the main canal but did not improve antimicrobial action in dentinal tubules. CO2 incorporation reduced the pH of NaOCl from ~13.4 to 7.4 and slightly increased the temperature, making the solution more chemically reactive. However, both oxidative stress markers and the XTT assay showed that the combination with CO2 impaired the antimicrobial effectiveness of NaOCl. Conclusions: Despite the improvement in bacterial reduction in the root canal lumen, the combination of PCD with NaOCl failed to enhance intratubular disinfection and reduced the oxidative damage and metabolic inactivation of the biofilm. CO2 pressurization appears to limit the antimicrobial action of NaOCl.

Influence of carbon dioxide addition on hydrogen-enriched diesel-WPO Blends in CI engines

ZusammenfassungIn einer One‐Pot‐Synthese wurden die bislang unbekannten schweren Homologe der Gruppe‐9‐Metall‐Carbine [(Me3P)3Co≡GeAr*] (1), [(Me3P)3Rh≡GeAr*] (2), [(Me3P)3Ir≡GeAr*] (3), [(Me3P)3Ir≡SnAr*] (5) und [(Et3P)3Ir≡PbAr*] (7) synthetisiert. [Ar* = C6H3‐2,6‐(Trip)2, Trip = 2,4,6‐C6H2iPr3]. Auch die Tetrylidine [(Me3P)3Rh≡SnAr*] (4) und [(Me3P)3Rh≡PbAr*] (6) wurden in einer One‐Pot‐Reaktion dargestellt. In einer neuartigen metathetischen Austauschreaktion reagieren die Übergangsmetallplumbylidine mit Terphenylstannylenchlorid zu den entsprechenden Stannylidinen, während diese in der Umsetzung mit Terphenylgermylenchlorid die entsprechenden Germylidine bilden. 31P{1H}‐NMR‐spektroskopische Untersuchungen der Metathesen zeigen den vollständigen Austausch des Tetrel‐[EAr]‐Fragments und, in der Reaktion des Rhodiumplumbylidins mit Stannylenchlorid, die Bildung eines Zwischenprodukts (Ar = Ar*, Tbb). Die Umsetzungen der Tetrylidine (2–5) mit Kohlenstoffdioxid ergeben die Produkte einer Redoxreaktion [(Me3P)3(CO)M‐E(η2‐O2CO‐κ2O)Ar*] [E = Ge, M = Rh (11), M = Ir (12); E = Sn, M = Rh (14), M = Ir (16)] mit einem am Übergangsmetall koordinierten Kohlenstoffmonoxidliganden und einem am Gruppe‐14‐Element koordinierten Carbonat. Für das Zinn wurden die durch die einfache CO2‐Addition gebildeten Intermediate [(Me3P)3M(μ,η2‐CO2‐κC:κO)SnAr*] [M = Rh (13), M = Ir (15)] isoliert.

A one-pot synthesis for previously unknown heavy homologues of Group 9 metal carbynes [(Me3P)3Co≡GeAr*] (1), [(Me3P)3Rh≡GeAr*] (2), [(Me3P)3Ir≡GeAr*] (3), [(Me3P)3Ir≡SnAr*] (5), and [(Et3P)3Ir≡PbAr*] (7) is presented [Ar* = C6H3-2,6-(Trip)2, Trip=2,4,6-C6H2iPr3]. During these preparations, the tetrylidynes [(Me3P)3Rh≡SnAr*] (4), and [(Me3P)3Rh≡PbAr*] (6), were also prepared in a one-pot procedure. In a hitherto unknown metathetical exchange reaction, the transition metal plumbylidynes were converted into the respective stannylidynes in reaction with terphenyl stannylene chloride, and the germylidynes were formed from the corresponding stannylidynes in reaction with terphenyl germylene chloride. These metathesis reactions were tracked by 31P{1H} NMR spectroscopy, which shows complete exchange of the tetrel [EAr]-fragment and the formation of an intermediate in the rhodium plumbylidyne reaction with stannylene chloride (Ar=Ar*, Tbb). Reactions of the tetrylidynes (2-5) with carbon dioxide yield the products of a redox reaction [(Me3P)3(CO)M-E(η2-O2CO-κ2O)Ar*] [E=Ge, M=Rh (11); M=Ir (12); E=Sn, M=Rh (14), M=Ir (16)] with a carbon monoxide coordinated at the transition metal and a carbonate coordinated at the Group 14 element. For tin the intermediates formed by mono CO2 addition [(Me3P)3M(μ,η2-CO2-κC:κO)SnAr*] [M=Rh (13), M=Ir (15)] have been isolated.

Cadmium catalyst with industrial polymeric nitrogen-containing ligand for the addition of carbon dioxide to oxiranes

Reactions of bis(hydrocarbyl)germylene manganese(I) hydride complexes [(dmpe)2MnH(GeR2)] (1a: R = Ph, 1b: R = Et) with carbon dioxide yielded the previously reported carbonyl formate complex [(dmpe)2Mn(κ1-O2CH)(CO)] (3) via the unstable κ2-formatogermyl intermediates [(dmpe)2Mn{κ2-GeR2(OCHO)}] (5a: R = Ph, 5b: R = Et). By contrast, addition of CO2 to [(dmpe)2MnH(GenBuH)] (2a), which contains a terminal GeH substitutent, resulted in the sequential formation of (i) the formatogermylene hydride complex [(dmpe)2MnH{GenBu(κ1-O2CH)}] (6), (ii) the isolable metallacyclic κ2-formatogermyl complex [(dmpe)2Mn{κ2-GenBu(κ1-O2CH)(OCHO)}] (7), and with heating(III) complex 3. Exposure of 2a to benzophenone also afforded a new germylene hydride complex, [(dmpe)2MnH{GenBu(OCHPh2)}] (8). Reactions of 1a-b and 2a with C(NiPr)2 afforded a family of stable metallacyclic κ2-amidinylgermyl complexes [(dmpe)2Mn{κ2-GeRR'(NiPrCHNiPr)}] (9a: R = R' = Ph, 9b: R = R' = Et, 10: R = nBu and R' = H). Addition of carbon dioxide to 10 yielded [(dmpe)2Mn{κ2-GenBu(κ1-O2CH)(NiPrCHNiPr)}] (11), and reaction of CO2 with the κ2-amidinylsilyl derivative [(dmpe)2Mn{κ2-SiPhH(NiPrCHNiPr)}] afforded [(dmpe)2Mn{κ2-SiPh(κ1-O2CH)(NiPrCHNiPr)}] (12). Complexes 6, 7, 8, 9a, 11, and 12 were crystallographically characterized, and DFT calculations were conducted to probe the effect that different substituents on Ge have on Mn-Ge bonding in κ2-formatogermyl, κ2-amidinylgermyl, and germylene complexes.

The corrosion properties of steel grade Steel 20 in the NACE environment with the addition of hydrogen sulfide and carbon dioxide were studied, the local corrosion rate in relation to the «pure metal» and in the case of corrosion inhibitors based on imidazolines and 4-methylcyclohexanone oxime was estimated. Based on the results of the work, it can be concluded that steel grade Steel 20 does not have high corrosion resistance in the NACE formation water model, the general corrosion rate over the entire exposure time interval is &gt; 0.1 mm/year, local corrosion damage is present, the local corrosion rate is &gt; 2.4 mm/year. The use of inhibitors of both the imidazoline type and based on 4-methylcyclohexanone oxime makes it possible to reduce the general corrosion rate to values not exceeding 0.4 and 0.2 mm/year, respectively (at an exposure time of 720 h), and reduce the local corrosion rate by at least 10 and 20 times, respectively.

The red alga Asparagopsis taxiformis has recently been recognized for its unique ability to significantly reduce methane emissions from ruminant animals when fed in small quantities. The main obstacle in using this seaweed as a methane-mitigating feed supplement is the lack of commercially available biomass. Little is known about how best to grow this red alga on a commercial scale, as there are few published studies that have investigated the factors that influence growth, physiology, and overall performance. This study examined the effects of temperature and CO2 enrichment on the growth, photophysiology, and concentration of bromoform, the secondary metabolite largely responsible for methane reduction in A. taxiformis. A series of single and multifactor closed culture experiments were conducted on A. taxiformis collected, isolated, and cultured from populations in Southern California. We identified the optimal temperature range to be between 22 and 26°C, with significant short-term stress observed below 15°C and above 26°C. Carbon dioxide addition resulted in increased performance, when accounting for growth per CO2 use. In general, we observed the highest bromoform concentrations in algae with the highest growth rates, but these results varied among experiments. These findings indicate that through environmental control and by addressing limiting resources, significant increases in biomass production and quality can be achieved.

Effects of carbon dioxide addition on soot dynamics in ethylene/air inverse diffusion flames: An experimental and computational analysis

The CdI2-catalyzed addition of CO2 to oxiranes is presented. The catalysts are obtained by mixing amines with CdI2. It is found that amines with a large number of aliphatic groups provide the higher conversion; the presence of additional OH and NH groups negatively affects the conversion.

Flame-retardant performance of a novel lignin-based rigid polyurethane foam prepared from pulping black liquor

The article presents the results of a study of the activity of deposited oxide catalysts in the process of obtaining formaldehyde from methanol. Model catalysts were prepared by impregnation of finely porous silica gel with nitrate solutions of zinc, copper, silver, sodium, followed by heat treatment. The catalytic properties of the samples were studied in the reaction of methanol dehydrogenation in the flow mode on a fine fraction of the catalyst. With the complication of the composition of the feed gas mixture, part of argon was replaced with hydrogen, mono- and carbon dioxide. The reaction mixture was analyzed by gas chromatography, IR spectroscopy and photocolorimetry. At a temperature of ~350 °C, a noticeable formation of formaldehyde begins, upon reaching a temperature of 500 °C in the reactor, methanol processing begins to decrease, while the concentration of formaldehyde changes insignificantly. Along with formaldehyde, dimethyl ether, methane and carbon dioxide are fixed in the reaction products. At the end of the tests on the surface of the catalyst, carbon, oxygen and hydrogen are quantified using elemental analysis methods, the ratio between which corresponds to the formula (-COH-)n. That is, along with the target reaction, methanol is consumed for the formation of surface hydrocarbons. Oxymethylene oligomers can decompose along two competing routes to form formaldehyde or carbon and CO2. The addition of carbon dioxide to the feed gas mixture after the catalyst enters the stationary mode leads to a significant increase in its formaldehyde yield. It is obvious that the route with the formation of carbon dioxide is associated with the target reaction of formaldehyde production, where the catalytic reaction maintains a certain concentration of active centers. Thus, it can be assumed that carbon dioxide as a product of decomposition of surface oxymethylene compounds affects the rate of the catalytic reaction by maintaining a certain concentration of surface hydrocarbons, which are necessary as an element of the active catalytic center. For citation: Morozov L.N., Vorobyov A.S., Kunin A.V., Egorov N.A., Timoshin E.S. Effect of the feed gas mixture composition at methanol dehydrogenation to formaldehyde on supported oxide catalysts. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 7. P. 88-95. DOI: 10.6060/ivkkt.20246707.7003.

Solid carbon can be transformed into activated char with higher reactivity through the activation process in a circulating fluidized bed (CFB) to improve the Boudouard reaction. A new technology for reducing CO2, the activated-reduction technology, was proposed. In order to investigate the influence of relevant parameters (carbon dioxide addition, oxygen concentration, and O2/C) of the activation process on the physicochemical properties and reactivity of activated char, the experiments were carried out on a bench-scale CFB. The relationship between the parameters and the reactivity of activated char is explored. The result shows that compared with the raw coal, the pore structure of activated char is developed, the number of active sites increases, the degree of graphitization decreases, and higher reactivity is possessed. For the activation process, less of the O2/C and moderate oxygen concentration promote the increase in activated char reactivity, which is conducive to the reduction of CO2. The results of the correlation discussion show that the reactivity is difficult to be characterized by a single simple parameter. The reactive specific surface area (RSSA) obtained by multiplying the mesoporous specific surface area and I D3+D4/I all has a good effect on describing the reactivity.

Abstract The article discusses the impact on the human body of breathing in an atmosphere of normobaric or slightly hyperbaric conditions, as well as breathing a mixture with an increased content of oxygen with the addition of carbon dioxide. The positive and negative effects breathing with an increased content of oxygen of hyperbaric conditions were compared with normobaric conditions and indications for their use were presented.

Model for estimating the effects of pressure and dilution on the flammability limits of fuels in constant-volume systems at subatmospheric pressure

Co-pyrolysis coking characteristics of nC12H26 and DHN/MeOH/EtOH/MF/DMF/H2O/H2/CO2/CO/N2 under supercritical condition

Explosion characteristics of hydrogen-nitrous oxide mixtures with carbon dioxide addition

Dissolution and recovery of poly(3-hydroxybutyrate) in switchable solvents and the formation of a switchable gel

One solution to the shortage of drinking water in Morocco is the development of reverse osmosis (RO) desalination plants. However, the quality of the permeate produced is corrosive, unbalanced, and does not meet the standards required for its use. The post-treatment process at the Al-Hoceima desalination plant in northern Morocco consists of the addition of carbon dioxide (CO2) and hydrated lime (Ca (OH)2). In this study, various analyses were utilized to assess the physical-chemical quality parameters of the water produced after remineralization. The results revealed that the remineralization method adopted by the plant is relatively complex and associated with difficulties in maintaining optimal remineralized water parameters such as pH, TAC, TH, and Ca2+. However, the water produced re-establishes its calcocarbonic balance and is of satisfactory quality for human consumption.