Effect Of Carbonaceous Materials Research Articles

(Invited) Effect of Carbonaceous Materials on the Performance of Supercapacitors

Carbonaceous materials such as carbon blacks, activated carbons, multi walled/single walled carbon nanotubes (CNTs), graphene oxide (GO), reduced graphene oxide (rGO), and biochar are found to be useful for energy storage applications because of their large specific surface area, high conductivity, high mechanical strength, good thermal stability, and low cost.In order to optimize the concentration of MWCNT in MnO2/MWCNT nanocomposite, we have synthesized MnO2/MWCNT nanocomposite with varying concentration of MWCNT such as pure MnO2, 1mg/ml, 4 mg/ml, and 10 mg/ml MWCNT in reaction mixture. The samples were identified as MnO2, M-CNT 100, M-CNT 400, and M-CNT 1000. From cyclic voltammetric studies at various scan rate, we plotted a graph between peak current () versus the scanning rate () and found that the slope of anodic (cathodic) peak for MnO2, M-CNT 100, M-CNT 400, and M-CNT 1000 were found to be 0.48 (0.42), 0.70 (0.61), 0.60 (0.54), and 0.52 (0.47), respectively. We also found that at a current density of 0.5 A/g, pure MnO2 has a specific capacitance of 124 F/g. The addition of MWCNT initially increases the specific capacitance to 145 F/g for M-CNT 100 nanocomposite; however, at the 400-mg and 1000-mg concentrations the specific capacitance decreases to 135 F/g and 102 F/g, respectively.Besides this, we have also studied the effect of binder on capacitive performance of MnO2/CuS/rGO samples and found that the specific capacitance of the composite materials increased upon decreasing the binder. The detailed results of our recent investigations on carbonaceous materials for supercapacitor applications will be presented at 244th ECS meeting.

Effects of Carbonaceous Materials with Different Structures on Cadmium Fractions and Microecology in Cadmium-Contaminated Soils.

Carbonaceous materials have proved to be effective in cadmium remediation, but their influences on soil microecology have not been studied well. Taking the structural differences and the maintenance of soil health as the entry point, we chose graphene (G), multi-walled carbon nanotubes (MWCNTs), and wetland plant-based biochar (ZBC) as natural and engineered carbonaceous materials to explore their effects on Cd fractions, nutrients, enzyme activities, and microbial communities in soils. The results showed that ZBC had stronger electronegativity and more oxygen-containing functional groups, which were related to its better performance in reducing soil acid-extractable cadmium (EX-Cd) among the three materials, with a reduction rate of 2.83–9.44%. Additionally, ZBC had greater positive effects in terms of improving soil properties, nutrients, and enzyme activities. Redundancy analysis and correlation analysis showed that ZBC could increase the content of organic matter and available potassium, enhance the activity of urease and sucrase, and regulate individual bacterial abundance, thereby reducing soil EX-Cd. Three carbonaceous materials could maintain the diversity of soil microorganisms and the stability of the microbial community structures to a certain extent, except for the high-dose application of ZBC. In conclusion, ZBC could better immobilize Cd and maintain soil health in a short period of time.

Ozonation of phenol in the presence of biochar and carbonaceous materials: The effect of surface functional groups and graphitic structure on the formation of reactive oxygen species

To develop a novel oxidation process using ozone and carbonaceous materials for water treatment and groundwater remediation, the effect of carbonaceous materials on the ozonation of phenol was investigated via batch experiments. Anode carbonaceous material (ACM) recovered from spent Li-ion batteries, graphite, granular activated carbon (GAC), and rice straw-derived biochar were evaluated as catalysts to enhance the ozonation of phenol. Compared with direct ozonation (28% removal in 2 h), the addition of carbonaceous materials enhanced the oxidation of phenol by ozone, showing 47%, 45%, 81%, and 74% removal with ACM, graphite, GAC, and biochar, respectively. According to the quenching experiments with chemical reagents and electron paramagnetic resonance analysis, reactive oxygen species, such as hydroxyl radicals (·OH), superoxide radicals (O2·-), and singlet oxygen (1O2), as well as electron transfer in the mediated-reaction, are included in the ozonation of phenol in the presence of carbonaceous materials. The oxygen-containing surface functional groups and graphitic structure are responsible for the reactive oxygen species and electron transfer reactions, respectively. Our results suggest that carbonaceous materials may be effectively used as catalysts to promote the ozonation of recalcitrant contaminants in water.

Effects of carbonaceous materials and particle size on oral and inhalation bioaccessibility of PAHs and OPEs in airborne particles.

Bioavailability of environmental contaminants is attracting considerable scientific attention due to growing awareness of its importance for risk assessment. In this study, size-segregated airborne particles were collected from six point-source sites, an urban residential site, and a sub-urban site. Potential factors governing bioaccessibility of the particle-bound polycyclic aromatic hydrocarbons (PAHs) and organophosphorus esters (OPEs) in stimulated gastrointestinal and respiratory tracts were elucidated. Particle concentrations of PAHs and OPEs at the eight sites were 2.4-32.3 ng/m3 and 1.6-19.9 ng/m3, respectively. In fine particles (with aerodynamic diameter less than 2.5 μm), 4- to 6-ring PAHs were more strongly correlated with organic carbon (OC) than elemental carbon (EC); while 3- and 4-ring PAHs in coarse particles (2.5-10 μm) tended to associate with EC. OPEs mostly showed significant correlations with EC in both fine and coarse particles. OC and EC exerted a significantly restraining effect on the oral and inhalation bioaccessibility of most hydrophobic organic contaminants (HOCs) in fine particles due to sorption of HOC molecules to these components. Furthermore, the effects varied, which could depend either on the emission sources (for oral bioaccessibility of PAHs) or the physicochemical properties of HOCs (for bioaccessibility of OPEs and inhalation bioaccessibility of PAHs). Linear regression between OC/EC contents and HOC bioaccessibility indicated that EC should play a more important role in the inhalation bioaccessibility than the oral bioaccessibility. Particle size of airborne particles is a relatively less significant factor determining the bioaccessibility.

Effects of Carbonaceous Materials with Different Structures on Cadmium Fractions and Microecology in Cadmium-Contaminated Soils

Effects of Carbonaceous Materials with Different Structures on Cadmium Fractions and Microecology in Cadmium-Contaminated Soils

The effect of carbonaceous materials on faradaic and charging current contribution in carbon paste electrodes investigated by chemometrics methods

Different carbon paste electrodes were prepared from carbonaceous materials including multi-walled carbon nanotubes (functionalized and pristine form), graphite powder, pencil graphite, and activated carbon. The electrochemical characteristics and different current contributions of these electrodes were quantitatively compared in K4[Fe(CN)6] and dopamine as two common benchmark redox system, using multivariate curve resolution–alternating least squares (MCR-ALS), as a powerful chemometrics technique. The total current of these electrochemical system recorded in potential-step mode was resolved to its three main current constituents including faradaic current, step charging current, and induced charging current. The contribution of each type of currents in total current was related to the structure and composition of the electrode as well as the nature of the analyte and supporting electrolyte. The focus of this study was on the contribution of faradaic current and nature of conductive phase in carbon paste electrodes. This approach can be effective for the identification of optimal electrode materials for voltammetric analysis and leads to new design criteria for carbon electrodes employed. The obtained results demonstrate that the nature of the conductive phase has a significant effect on faradaic current contribution. Results showed that activated carbon, as conductive phases, has the minimum contribution of faradaic current whereas functionalized multi-walled carbon nanotube has the maximum contribution of faradaic current compared with other carbonaceous materials.

Broadband Measurements of the Complex Permittivity of Carbonaceous Asteroid Regolith Analog Materials

AbstractWe develop a full methodology to measure the complex relative permittivity of planetary regolith analog materials in vacuum and up to 120 °C over a broad range of frequencies (400 MHz to 8.5 GHz or wavelengths 18.8–3.5 cm). We demonstrate our method with measurements of analog regolith materials appropriate for asteroid (101955) Bennu, the target of National Aeronautics and Space Administration's OSIRIS‐REx mission: individual and mixed components of UCF/DSI‐CI‐2, a new carbonaceous asteroid regolith simulant produced by Deep Space Industries based on CI chondrite meteorite mineralogy. We measure, for the first time, the effect of carbonaceous material on the complex relative permittivity of asteroid regolith analogs by measuring the powdered serpentine component of the simulant mixed with varying amounts of carbonaceous material in vacuum at 25 and 40 °C. We find that at a bulk density of 1.60 g/cm3 and wavelength of 12.6 cm, serpentine with 5 wt% carbonaceous material has = 3.30 ± 0.01 and = 0.016 ± 0.003 and that carbonaceous material increases the attenuation of electromagnetic energy in our samples. Ground‐based radar (at 12.6‐ and 3.5‐cm wavelengths) has previously been used to investigate carbonaceous asteroid (101955) Bennu. Our measurements provide new constraints on the attenuation of radar energy in granular carbonaceous materials.

Effects of carbonaceous materials on the physical and electrochemical performance of a LiFePO 4 cathode for lithium-ion batteries

Effects of carbonaceous materials on the physical and electrochemical performance of a LiFePO 4 cathode for lithium-ion batteries

Effects of carbonaceous materials on the physical and electrochemical performance of a LiFePO 4 cathode for lithium-ion batteries

The effects of carbonaceous materials on the physical and electrochemical performance of LiFePO 4/C hybrids are reviewed. The major role, advantages and disadvantages of carbon-based materials in LiFePO 4/carbon hybrids are discussed. The introduction of an in situ grown carbon coating would be beneficial to limiting the LiFePO 4 particle growth and increasing the electric conductivity. The structure and precursors of the in situ grown carbons have a great influence in the rate performance of the hybrids, which can be related to an improved electron and ion transfer rate. Deposition of LiFePO 4 into a carbonaceous matrix such as a templated membrane can increase the contact area between the active materials and the electrolyte, which favors a fast ion transport. The addition of conductive carbon and graphene would only effectively increase the electrical conductivity. In order to achieve an excellent electrochemical performance of LiFePO 4, it is necessary to take advantage of and to combine these approaches to optimize electron and ion transfer rates. Also, it is most important to minimize the carbon content in LiFePO 4/carbon hybrids to increase volumetric energy density and tap density when practical applications in electric vehicles are targeted.

Potassium hydroxide modified active carbon for adsorptive refrigerators

Active carbon-methanol pair appears to be suitable for adsorptive cooling systems. The porous structure of commercial active carbon was modified by potassium hydroxide treatment at 750 °C. Such treatment develops the specific surface area of carbon, changes nature of its surface and significantly increases the heat of wetting. The applied way for active carbon modification gives possibility of modeling porous structure, character surface and heat effects of carbonaceous materials for adsorptive refrigerators.

Effect of carbonaceous materials on electrochemical properties of nano-sized Fe 2O 3-loaded carbon as a lithium battery negative electrode

Nano-sized Fe 2O 3-loaded carbon material was prepared by loading Fe 2O 3 on carbon using various carbonaceous materials. Carbonaceous materials strongly affected the electrochemical behavior of nano-sized Fe 2O 3-loaded carbon. Among the carbons used, nano-carbons such as acetylene black (AB), tubular carbon nanofibers (CNF), and platelet CNF provided larger capacities than other carbons. This may be due to the greater surface area of nano-carbon, which gives a greater distribution of nano-sized Fe 2O 3 particles than other carbons and delivers a greater capacity than other carbons. Investigation of the first-cycle materials by X-ray photoelectron spectroscopy (XPS) revealed that Fe 2O 3 was reduced to Fe metal in the charge process (reduction of Fe 2O 3), and, conversely, Fe metal was not completely oxidized to Fe 2O 3 during discharge (oxidation of Fe). This result may be due to the covering of non-conductive Li 2O formed during charging.

Measurements of non-volatile fractions of pollution aerosols with an eight-tube volatility tandem differential mobility analyzer (VTDMA-8)

A volatility tandem differential mobility analyzer (VTDMA) was developed that offers high size resolution with high temporal resolution: the eight heating columns of the VTDMA-8 allow rapid measurement of the non-volatile component of aerosol particles within a narrow particle size range in about 15 min . The non-volatile composition of these quasi-monodisperse particles is described in terms of number fraction Φ N and volume fraction Φ V of the non-volatile material. Laboratory studies were made to determine the transfer efficiency and the volatile behavior of sulfate particles in the VTDMA-8. Its applicability to atmospheric aerosols was confirmed during three field measurements. Since the distribution of carbonaceous material depends on the distance to combustion sources and varies with region (i.e., urban or rural) and with time, we made continuous surface measurements in air masses polluted to different levels: (a) in Falkenberg, a moderately polluted, rural region in north-eastern Germany, (b) in the city of Leipzig, a strongly polluted environment, and (c) directly at a combustion source in the exhaust of a diesel-fueled vehicle. The results show that the refractory material contained in 150 nm atmospheric particles (at Falkenberg and Leipzig) ranged between 8% and 25% in volume and represents an external mixture of particles containing various amounts of non-volatile material. However, the vehicle-emitted 50 nm particles at a single combustion source were internally mixed, and that non-volatile fraction ranged between 75% and 98% in volume, depending on the operating conditions of the vehicle (speed, engine revolution). The results show that throughout all measurements the total number of particles remained unchanged after evaporation of the volatile material. Our results demonstrate that the VTDMA-8 can rapidly measure the non-volatile fractions of size-segregated pollution aerosols and that it is applicable to study the mixing state of aerosols and the effect of carbonaceous material on aerosol aging processes.

Effect of Carbonaceous Materials on the Oxidation of Phenol in Supercritical Water: A Preliminary Study

Supercritical water oxidation of phenol in the presence of various carbonaceous materials was studied. Coconut shell activated carbon, bamboo charcoal, coke, graphite, and carbon fiber were used as the additives. As a result, all of the carbon additives examined were revealed to have a catalytic effect to promote the oxidative decomposition of phenol.

SiO<SUB>2</SUB>の炭素還元速度におよぼす炭材の影響

SiO<SUB>2</SUB>の炭素還元速度におよぼす炭材の影響

Effects of carbonaceous materials on the accumulation of readily mineralizable organic nitrogen in soil

Abstract Decomposition of organic nitrogenous materials in soil was affected by C/N ratio. Immobilization of nitrogen mineralized from nitrogenous material added to the soil was influ enced by the degradability of carbonaceous and nitrogenous materials. The turnover of nitrogen which had been freshly immobilized in the presence of glucose in the soil was faster than that immobilized with cellulose or lignin. The effect of soil-drying on the mineralization of organic nitrogen immobilized through the decomposition of carbonaceous and nitrogenous materials in the soil depended significantly on the availability of carbonaceous materials as a microbial energy source. However, the drying effect was not always proportional to the amount of organic nitrogen accumulated in the soil.