Carbon Sorbents Research Articles

IODINE FILTER CONTROL STAND (SKIF) FOR CERTIFICATION CARBON SORBENT VENTILATION SYSTEMS OF NPP

The article provides information on the creation of the first iodine filter control stand (SKIF) in Ukraine, designed to determine the coefficient of purification of gaseous radioactive emissions from iodine and methyl iodide by sorbents used in ventilation systems at Ukrainian nuclear power plants. The possibility of using a stable isotope of iodine to determine the adsorption capacity of carbon sorbents is substantiated. The development, installation, start-up and adjustment of the pumping module and the measuring module were carried out when using air mixtures with methyl iodide based on the stable isotope of iodine 127I. The developed software allows you to use the stand in automatic mode. The manual for the operation of the SKIF stand was created and the method of determining the coefficient of purification of ventilated air from methyl iodide by carbon sorbents was certified within the framework of the enterprise standard.

A Study of Promising Carbon Sorbents Prepared via High-Temperature Activation in Purification Processes of Aqueous Solutions from Dyes

A Study of Promising Carbon Sorbents Prepared via High-Temperature Activation in Purification Processes of Aqueous Solutions from Dyes

Use of carbon sorbents to extract manganese from solutions

One of the most common elements present in naturally occurring waters, manganese is an essential trace element, whose daily intake requirement by the human body is around 5–7 mg. While a lack of manganese in drinking water can lead to negative health consequences, a high manganese content in water and increased daily intake leads to the blocking of enzymes used in the conversion of inorganic iodine to organic, additionally changing inactive diiodothyronine into the active hormone thyroxine. The study investigates the possibility of using carbon sorbents having a microporous structure to change the manganese content in aqueous solutions. The adsorption capacity of One of the most common elements present in naturally occurring waters, manganese is an essential trace element, whose daily intake requirement by the human body is around 5–7 mg. While a lack of manganese in drinking water can lead to negative health consequences, a high manganese content in water and increased daily intake leads to the blocking of enzymes used in the conversion of inorganic iodine to organic, additionally changing inactive diiodothyronine into the active hormone thyroxine. The study investigates the possibility of using carbon sorbents having a microporous structure to change the manganese content in aqueous solutions. The adsorption capacity of manganese significantly depends on the acidity of the medium. The highest adsorption value of manganese (II) cations is observed in a weakly alkaline medium (pH 7.5). Kinetic studies demonstrated the possibility of describing the interaction using a pseudo first-order equation. The reaction rate constant as calculated by graphical and computational variants was 0.067 s-1. A functional assessment of the adsorption process can be represented by monomolecular adsorption isotherms, which are described by the classical Langmuir equation. The characteristic adsorption constant parameters were as follows: limiting adsorption value – 1.68 mmol/g; adsorption equilibrium constant – 0.979×103 at a temperature of 298 K. Gibbs energy at 298 K is equal to – 7.41 kJ/mol. The study of the process at elevated temperatures of 308, 318 and 328 K indicates its exothermic nature. With heating, the limiting adsorption decreases.

Using L. minor and C. elegans to assess the ecotoxicity of real-life contaminated soil samples and their remediation by clay- and carbon-based sorbents

Toxic substances, such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals, can accumulate in soil, posing a risk to human health and the environment. To reduce the risk of exposure, rapid identification and remediation of potentially hazardous soils is necessary. Adsorption of contaminants by activated carbons and clay materials is commonly utilized to decrease the bioavailability of chemicals in soil and environmental toxicity in vitro, and this study aims to determine their efficacy in real-life soil samples. Two ecotoxicological models (Lemna minor and Caenorhabditis elegans) were used to test residential soil samples, known to contain an average of 5.3, 262, and 9.6 ppm of PAHs, lead, and mercury, for potential toxicity. Toxicity testing of these soils indicated that 86% and 58% of soils caused ≤50% inhibition of growth and survival of L. minor and C. elegans, respectively. Importantly, 3 soil samples caused ≥90% inhibition of growth in both models, and the toxicity was positively correlated with levels of heavy metals. These toxic soil samples were prioritized for remediation using activated carbon and SM-Tyrosine sorbents, which have been shown to immobilize PAHs and heavy metals, respectively. The inclusion of low levels of SM-Tyrosine protected the growth and survival of L. minor and C. elegans by 83% and 78%, respectively from the polluted soil samples while activated carbon offered no significant protection. These results also indicated that heavy metals were the driver of toxicity in the samples. Results from this study demonstrate that adsorption technologies are effective strategies for remediating complex, real-life soil samples contaminated with hazardous pollutants and protecting natural soil and groundwater resources and habitats. The results highlight the applicability of these ecotoxicological models as rapid screening tools for monitoring soil quality and verifying the efficacy of remediation practices.

Prospects for Obtaining Carbon Sorbents from D and DG Grade Coals

Prospects for Obtaining Carbon Sorbents from D and DG Grade Coals

Microwave Exfoliated Graphene Oxide for Sorption Concentration of Gold and Silver

A method has been reported for determining of Au and Ag in waters using preliminary sorption concentration of these analytes by microwave exfoliated graphene oxide (GO) and quantitative analysis by two-jet arc plasma atomic emission spectrometry (TJP-AES) and graphite furnace atomic absorption spectrometry (GFAAS). The parameters of sorption of analytes such as duration of sorption and pH were optimized for the preliminary concentration of Au and Ag on various carbon sorbents for subsequent TJP-AES and GFAAS analysis. The sorption properties of carbon nanotubes (CNTs), multilayer graphene (MLG) and GO such as sorption capacity and surface area were compared. The content of analytes in sorption materials was defined. The results demonstrated that GO provides the best sorption properties and the use of exfoliated GO for preconcentration decreaces the blank signal from nonselective absorption by 10 to 120 times. The limits of detection (LODs) for Au and Ag are 4·10−1 µg L−1 and 8·10−2 µg L−1 by GFAAS and 5 µg L−1 and 2·10−1 µg L−1 by TJP-AES.

Chemical Activation of Banana Peel Waste-Derived Biochar Using KOH and Urea for CO2 Capture.

This article describes the synthesis and characterization of porous carbon derived from waste banana peels by chemical activation with KOH or by activation KOH and urea modification. The as-synthesized samples were carefully characterized by various techniques. The prepared carbonaceous materials possess highly developed micropore and mesopore structures and high specific surface area (up to 2795 cm2/g for materials synthetized with KOH and 2718 cm2/g for activated carbons prepared with KOH and urea). A series of KOH-activated samples showed CO2 adsorption at 1 bar to 5.75 mmol/g at 0 °C and 3.74 mmol/g at 25 °C. The incorporation of nitrogen into the carbon sorbent structure increased the carbon uptake capacity of the resulting materials at 1 bar to 6.28 mmol/g and to 3.86 mmol/g at 0 °C and 25 °C, respectively. It was demonstrated that treatment with urea leads to a significant increase in nitrogen content and, consequently, CO2 adsorption, except for the material carbonized at 900 °C. At such a high temperature, almost complete decomposition of urea occurs. The results presented in this work could be used in the future for utilization of biomass such as banana peels as a low-cost adsorbent for CO2 capture, which could have a positive impact on the environment and human health protection.

The Effect of Nitrogen Functional Groups on Pb0, PbO, and PbCl2 Adsorption over a Carbonaceous Surface.

Lead (Pb) pollution, especially from the incineration of municipal solid waste (MSW), poses a significant threat to the environment. Among all the effective methods, activated carbon (AC) injection serves as an effective approach for lead removal from flue gas, while the modification of ACs emerges as a crucial pathway for enhancing Pb adsorption capacities. Density functional theory (DFT) is employed in this study to investigate the mechanisms underlying the enhanced adsorption of Pb species (Pb0, PbO, and PbCl2) on nitrogen-functionalized carbonaceous surfaces. The results show that nitrogen-containing groups substantially enhance lead adsorption capacity, with adsorption energies ranging from -526.18 to -288.31 kJ/mol on nitrogen-decorated carbonaceous surfaces, much higher than those on unmodified surfaces (-310.35 to -260.96 kJ/mol). Additionally, electrostatic potential and density-of-states analyses evidence that pyridinic nitrogen atoms remarkably expand charge distribution and strengthen orbital hybridization, thereby augmenting lead capture. This research elucidates the role of nitrogen-containing functional groups in lead adsorption, offering valuable insights for the development of highly efficient biomass-derived activated carbon sorbents for lead removal.

Leveraging Curvature on N-Doped Carbon Materials for Hydrogen Storage.

Carbon sorbent materials have shown great promise for solid-state hydrogen (H2) storage. Modification of these materials with nitrogen (N) dopants has been undertaken to develop materials that can store H2 at ambient temperatures. In this work density functional theory (DFT) calculations are used to systematically probe the influence of curvature on the stability and activity of undoped and N-doped carbon materials toward H binding. Specifically, four models of carbon materials are used: graphene, [5,5] carbon nanotube, [5,5] D5d-C120, and C60, to extract and correlate the thermodynamic properties of active sites with varying degrees of sp2 hybridization (curvature). From the calculations and analysis, it is found that graphitic N-doping is thermodynamically favored on more pyramidal sites with increased curvature. In contrast, it is found that the hydrogen binding energy is weakly affected by curvature and is dominated by electronic effects induced by N-doping. These findings highlight the importance ofmodulating the heteroatom doping configuration and the lattice topology when developing materials for H2 storage.

Entropy driven separation of xylene isomers on graphitic carbon adsorbents

Separation of xylene isomers remains one of the most important and challenging applications of adsorption-based separations in petrochemical industry. Despite the sustainable success of zeolite-based separations a search for efficient adsorbents selective for xylenes, especially para-xylene, is constantly ongoing. In this work, a potentially scalable chromatographic separation of all three xylenes was achieved on graphitic carbon sorbents, including a self-packed sorbent based on an oligo-graphene. A curious feature of this separation is stronger retention of para-xylene than meta- and, in some conditions, even than ortho-xylene. Noticeably, separation selectivity between para- and meta-isomers does not depend on temperature. Apparently, lower entropy of para-xylene in solution due to its higher molecular symmetry leads to a lesser adsorption entropy loss, which makes its adsorption statistically more likely. The concept of using carbon adsorbents for entropy driven chromatography separations may be useful for the isolation of xylenes from their mixture and, possibly, for other positional isomers separation.

Erratum to: Influence of Mineral Compounds on the Extraction of Phenol from Mine Wastewater by Carbon Sorbents

Erratum to: Influence of Mineral Compounds on the Extraction of Phenol from Mine Wastewater by Carbon Sorbents

TREATMENT OF LEACHATE BY THE CARBON MATERIAL OBTAINED FROM POLYMER FRACTION OF MUNICIPAL SOLID WASTE

In the study, the process of anaerobic thermal processing of polymer fraction of municipal solid waste using a horizontal and vertical type of reactor has been developed in order to obtain a new carbon sorbent. The productivity of carbon material by the horizontal method is 20%, while vertical type of reactor is about 30%. The sorption potential of some heavy metals and microbiological indices from leachate water of Tbilisi municipal solid waste polygon has been studied. According to estimates, the sorption potential of pollutans from wastewater using our new sorbent is average 60-98%.

ECOLOGICAL AND ECONOMIC JUSTIFICATION OF THE EFFICIENCY OF CARBON SORBENTS BASED ON SAWWOOD OF DIFFERENT TREES

The paper analyzes the effectiveness of the use of carbon sorbents based on sawdust of various tree species in decontamination of fuel and lubricants. The advantages of using the sorption method as an effective, widespread, simple and affordable method for cleaning oil products are substantiated. Attention is focused on the quality of the sorbent material for the use of carbon sorbents from sawdust of various tree species. The structural, physico-chemical, absorption and sorption characteristics of carbon sorbents from vegetable raw materials are given and the effectiveness of their use for cleaning water and soil environments is shown. The ecological and economic advantages of cleaning the water and soil environment from oil products with carbon sorbents from plant raw materials, compared to other methods and means of cleaning, are revealed.

Static iodine loading comparisons between activated carbon, zeolite, alumina, aerogel, and xerogel sorbents

Different sorbents, including activated carbons, an aerogel, xerogels, an alumina, a zeolite, and a carbon foam were investigated for static I2(g) loading at 71 °C for 56 d followed by 4.7 d of desorption.

LiCl in situ decorated metal-organic framework (MOF)-derived porous carbon for efficient solar-driven atmospheric water harvesting.

Solar-powered sorption-based atmospheric water harvesting (AWH) technology is a promising solution to the freshwater scarcity in arid regions. Existing adsorbent materials still face challenges in aspects such as cycling stability and adsorption kinetics and require further development. Herein, we presented a strategy for the in situ fabrication of high-performance adsorbents, lithium chloride (LiCl)-decorated metal-organic framework (MOF)-derived porous carbon sorbents (PCl), via high-temperature pyrolysis and hydrogen chloride (HCl) vapor treatment. The sorbents display high adsorption capacity across a wide range of humidity water adsorption capacities in a wide humidity range with the maximum adsorption capacity of 7.87 g g-1, and rapid response to the solar-driven process and excellent cyclic stability. The LiCl nanocrystals in PCl can be utilized efficiently and decorated within the porous framework stably, and demonstrate water adsorption at 20%, 40%, 60% and 80% RH, of 1.34, 1.69, 2.56 and 4.23 gH2O·gLiCl-1, respectively, and significantly higher water uptake and release rates than bulk LiCl. This may provide new guides for designing efficient solar-driven AWH.

Hydrothermal Synthesis of High-Efficiency Carbon Sorbent Based on Renewable Resources

Hydrothermal Synthesis of High-Efficiency Carbon Sorbent Based on Renewable Resources

Study of the physicochemical characteristics of modified carbon sorbents based on wood waste

The use of dispersed wood in the development of methods for producing sorption materials based on it becoming increasingly economically feasible, however, to solve practical problems, materials with a certain porous structure and surface chemistry are required. This article presents a study of the physicochemical characteristics of carbon sorbents obtained by modifying sawdust (SD) of Scots pine (Pinus sylvestris). It has been established that variations in thermal modification (annealing at a temperature of 300±10°C for 35 minutes) and chemical treatment of sawdust samples of fraction 0.75-2.0 mm with a solution of 5 M nitric acid contributed to an increase in the total pore volume (from 5.787 to 8.648 cm3/g) and adsorption activity for methylene blue (from 31.2 to 47.6 mg/g). At the same time, the swelling and bulk density of the resulting micro- and/or mesoporous carbon sorbents were somewhat lower than the values for native sawdust. Changes in the composition of functional groups of all samples were monitored by Fourier transform IR spectroscopy and potentiometric titration using the Boehm method. It was revealed that the thermal modification of wood waste by annealing led to an increase in the total number of oxygen-containing groups on the surface by 2.3 times (from 2.3 to 5.33 mEq/g). The modification of the surface of the original and heat-treated sawdust by oxidation with nitric acid solutions at a temperature of 80°C for 5 h also contributed to an increase in the total number of oxygen-containing groups by more than 3 times, but with an increase in the concentration of HNO3 from 0.5M to 5M the number of carboxyl groups decreased with a simultaneous increase in the content of hydroxyl groups. The extraction of copper(II) ions occurs as a result of ion exchange on the functional groups of carbon sorbents, and the maximum sorption capacity of the studied samples depended on the method of their modification. The sorption of copper(II) ions by initial sawdust is most accurately described by the Dubinin-Radushkevich model, and the sorption of carbon sorbents modified by various methods is best described by the Langmuir model. It has been shown that the chemical modification of native and thermally treated samples with a 5 M HNO3 solution allows to obtain sorbents with the best sorption capacity with respect to Cu(II) ions.

Study of sorption of platinum, palladium and rhodium ions on a carbon sorbent

The article is devoted to the sorption concentration of platinum (II,IV), palladium (II) and rhodium (III) ions from chloride media on a carbon synthetic sorbent. For the study of the sorption concentration of platinum group metals, the carbon synthetic sorbent Lewatit AF5 was chosen. This sorbent has high mechanical strength, high surface area, narrow pore size distribution, and low cost compared to silicate or polymer sorbents. Sorption concentration was carried out under static conditions from model chloride solutions. The concentration of analytes in the initial solutions ranged from 8 to 50 mmol/dm3. Equilibrium concentrations of metals in solutions were determined by inductively coupled plasma atomic emission spectrometry. The dependences of adsorption on contact time, free acidity and redox potential of the system were studied, and the limiting absorption values for each of the metals studied were determined. The study of the kinetic parameters of the sorption of Pt (IV), Pd (II) and Rh (III) ions was carried out from chloride solutions characterized by free acidity values of 0.01 mol/dm3. The time for establishing sorption equilibrium was determined, which was 4 hours for each of the ions. When studying the dependence of adsorption on free acidity and the oxidation-reduction potential of the system (ORP), it was revealed that with an increase in free acidity and redox potential, a decrease in sorption activity is observed, thus we can conclude that aquated complexes of platinum metals, in which metals present not in the highest oxidation state, involved in the sorption process. Processing of experimental data showed the applicability of the linear equation of the Langmuir isotherm for the description of the adsorption process, the limiting adsorption values were calculated, using which the sorption capacity of the sorbent was assessed. The sorption capacity for Pt (II, IV), Pd (II) and Rh (III) was 1.24 mmol/g; 1.16 mmol/g and 0.57 mmol/g, respectively. High values of sorption capacity, as well as a fairly short time to achieve sorption equilibrium without the use of means for the acceleration of the process, in combination with the mechanical characteristics of the sorbent, allow us to conclude that the Lewatit AF5 sorbent is promising for the concentration of platinum group metals from hydrochloric acid solutions.

Optimization of a Natural Gas Power Plant with Membrane and Solid Sorbent Carbon Capture Systems

Carbon capture & storage (CCS) with high capture rates (90-99%) will be necessary to keep natural gas around in a low-carbon future. Furthermore, as intermittent renewable energy expands, natural gas power plants will have to operate at low-load conditions more frequently. To meet these demands, we propose a natural gas combined cycle (NGCC) power plant with a hybrid CCS system that can attain high capture rates and easily cycle between high-load and low-load conditions. More specifically, we propose an integrated system where natural gas exhaust is first processed by a membrane CCS system and then by a solid sorbent CCS system. We integrated models of an NGCC plant, a membrane carbon capture system and a solid sorbent carbon capture system into a single optimization platform to maximize the net present value (NPV) and carbon capture rate of the integrated system. The optimization results indicate a 99.3% carbon capture rate from the inlet natural gas stream at high-load conditions, and a 99.6% carbon capture rate from the inlet natural gas stream at low-load conditions. Compared to a baseline NGCC system without carbon capture, the integrated system has a higher NPV, which indicates that performing carbon capture is more profitable than operating an NGCC system without carbon capture in a future with CO2 taxes. Compared to a baseline NGCC system with an amine-based CCS system that performs 90.7% carbon capture, the proposed integrated system captures more carbon and emits less CO2, while still maintaining a competitive CO2 capture cost.

Simulation of Biogas Upgrading by Sorption-Enhanced Methanation with CaO in a Dual Interconnected Fluidized Bed System

In this work, ASPENplus was used to simulate biogas upgrading by sorption-enhanced methanation in a dual interconnected bubbling fluidized bed configuration using inexpensive, abundant, and eco-friendly CaO to remove H2O from the reaction environment. The chemical looping scheme consisted of two reactors: a methanator/hydrator, where the catalytic reactions occurred on a catalyst with 20% Ni supported on alumina as well as the steam removal by CaO, and a regenerator, where the Ca(OH)2 was dehydrated back to CaO. The simulations were carried out to identify possible reactant compositions (H2 and biogas), CaO amount, and the methanation temperature able to produce an outlet gas matching the specifications for direct grid injection. When considering a stoichiometric gas feed ratio at the methanator inlet, the unwanted CaO carbonation worsened the process performance, subtracting CO2 from the desired methanation reaction. However, optimal conditions were found with hydrogen-lean gas feedings, balancing the limited H2 amount with the capture of CO2 due to the sorbent carbonation. Thermodynamic considerations pointed out the possibility of solid carbon formation induced by sorption-enhanced methanation conditions, especially for H2 sub-stoichiometric feedings.