Surface Of Carbonaceous Materials Research Articles

Studies on the Process of Basic Dyes Adsorption on Uniform Spherical Carbons.

The influence of carbon pore structure on the sorption process of selected cationic dyes has been investigated. The structure and surface of carbonaceous materials have been characterized basing on various techniques: scanning electron microscopy, low temperature nitrogen adsorption-desorption measurements, X-ray photoelectron spectroscopy and thermal analysis combined with identification of gaseous products. The kinetic and equilibrium adsorption measurements of Basic Violet 3, Basic Red 1 and Basic Blue 9 from aqueous media were performed. The studied carbons seem to be promising adsorbents towards dyes, taking into account the easy-to-use uniform spherical form of the granules and a complex type of porosity with micro-, meso- and macropores appropriate for large molecule adsorption.

Activated Biocarbons Obtained from Plant Biomass as Adsorbents of Heavy Metal Ions.

This paper deals with the adsorption of heavy metal ions on the surface of carbonaceous materials obtained via the chemical activation of biomass. Waste plum stones, pine sawdust and horsetail herb were used as the precursors of carbonaceous adsorbents. The effect of the precursor type and preparation procedure on the physicochemical properties of activated biocarbons and their sorption abilities towards Pb(II) and Cu(II) ions have been checked. The obtained micro-mesoporous activated biocarbons were characterized by determination of elemental composition and ash content, the number of surface functional groups and pH of water extracts as well as textural study based on low temperature nitrogen adsorption/desorption and scanning electron microscopy. Additionally, the electrokinetic studies including solid surface charge density and zeta potential determination were performed. Moreover, the adsorption data modelling (equilibrium and kinetics), XPS results analysis and comparison of parameters characterizing electrical double layer formed at the solid-liquid interface enabled the specification of the mechanism of heavy metals binding with the activated biocarbons surface. The maximum adsorption capacity towards copper and lead ions (177.5 and 178.1 mg/g, respectively) was found for plum stone-based activated biocarbon. For all carbonaceous materials, better fit to the experimental data was achieved with a Langmuir isotherm than a Freundlich one. In turn, a better fit of the kinetics data was obtained using the pseudo-second order model.

Carbonaceous material prepared by pyrolysis of refinery oily sludge for removal of flotation collectors in wastewater.

The carbonaceous material (CM) prepared by refinery oily sludge was proposed to remove flotation collectors, butyl xanthate (BX), and diethyldithiocarbamate (DDTC) in synthetic wastewater. The effects of the CM on removal efficiency, adsorption kinetics, and isotherms were experimentally carried out. The surface structure and composition of CM were characterized by BET isotherm, XRD, and SEM-EDS, and the concentration of BX and DDTC was tested by UV-VIS spectrometer. The adsorption behavior and removal mechanism were investigated by zeta potential, ToF-SIMS, FTIR, etc. The removal efficiencies of BX and DDTC were both more than 99%, and the maximum adsorption capacity peaked when the pH of the solution was neutral. The two collectors were heterogeneous adsorption on the surface of CM. BX, DDTC, and related metal compounds were found on the surface of carbonaceous material, confirming the existence of both physical and chemical adsorption, and physical adsorption accounted for the main mechanism. It is proved that BX and DDTC can be removed by carbonaceous material and realize the high-effective utilization of refinery oily sludge.

Unraveling Synergistic Redox Interactions in Tetraphenylporphyrin-Polyluminol-Carbon Nanotube Composite for Capacitive Charge Storage.

Organic redox-active materials, combined with high-surface-area carbonaceous substrates, form sustainable and low-cost composites with greatly enhanced electrochemical charge storage capacities. The electrochemical capacitive behavior of a composite electrode containing tetraphenylporphyrin sulfonate (TPPS), Chemically polymerized luminol (CpLum), and carbon nanotubes (TPPS-CpLum-CNT) was studied and compared with individual TPPS-CNT and CpLum-CNT composites. The dual-layer TPPS-CpLum had a combined contribution to the electrochemical charge storage, which led to an increased volumetric capacitance over the bare CNT and individual TPPS-CNT and CpLum-CNT composites. The synergistic interactions in the composite enabled faster charge storage kinetics and great stability. Spectroscopic analyses revealed that TPPS and CpLum interact electronically through noncovalent π-π and van der Waals bonds, which facilitates the transfer of electrons during charge and discharge. The synergy in charge storage was confirmed by density functional theory computational analysis, which suggested favorable physisorption and interfacial electronic interactions for TPPS adsorbed to a CpLum-carbon substrate. The combined insights from experimental and computational characterizations show that superimposing redox-active organic layers can be an effective and sustainable approach to design and engineer the surface of carbonaceous materials for capacitive charge storage.

Synthesis and Characterization of Nanoporous Carbon Carriers for Losartan Potassium Delivery.

Losartan potassium is most commonly used for the treatment of hypertension. In recent years, new applications of this drug have emerged, encouraging the design of novel nanoporous carriers for its adsorption and release. The purpose of this study was to synthesize ordered mesoporous carbon vehicles via a soft-templating method altered with the use of nitrogen precursors and via a hard-templating method followed by chitosan functionalization. As a result, the materials obtained differed in nitrogen content as well as in the number of total surface functional groups. The impact of the modification on the physicochemical properties of carbon carriers and their interaction with losartan potassium during adsorption and release processes was examined. The materials were characterized by various morphologies, specific surface areas (101–1180 m2 g−1), and the amount of acidic/basic oxygen-containing functional groups (1.26–4.27 mmol g−1). These features, along with pore sizes and volumes, had a key effect on the sorption capacity of carbon carriers towards losartan potassium (59–161 mg g−1). Moreover, they contributed to the differential release of the drug (18.56–90.46%). Losartan potassium adsorption onto the surface of carbonaceous materials was mainly based on the formation of hydrogen bonds and π–π interactions and followed the Langmuir type isotherm. It has been shown that the choice of the method of carbon carriers’ synthesis and their modification allows for the precise control of the kinetics of the losartan potassium release from their surface, resulting in rapid or sustained drug liberation.

Effect of Carbonaceous Material Surface Texture on Iron Carburization Reaction under Loading Condition

Effect of Carbonaceous Material Surface Texture on Iron Carburization Reaction under Loading Condition

Enhanced performance of carbon-based supercapacitors by constructing protonic and electric dual-channels in electrodes

Powdery carbonaceous materials have to use binder materials when they are integrated into electrodes for supercapacitors, which will results in high interfacial charge transfer resistances and reduced specific capacitance. To resolve the problem, protonic and electric dual-channels are constructed in electrodes by in situ synthesis of cesium hydrogen salt of phosphotungstic acid on the surface of carbonaceous materials. The cesium hydrogen salt particles are confirmed by a Fourier transform infrared spectroscopy, X-ray diffractometer and an energy dispersive X-ray spectroscopy. The electrochemical properties of as-fabricated electrodes are measured by cyclic voltammetry, galvanostatic charging-discharging, and impedance analysis with an electrochemical workstation. At a current density of 1 A g−1, the electrode shows a specific capacitance of 152 F g−1. Compared to the electrode without the cesium hydrogen salt, the value increases 25% at least. Furthermore, the specific capacitance retention of the electrode reaches 104% of its original capacitance after 5000 charge-discharge cycles, suggesting excellent cycling stability.

Theoretical Study on Hg0 Adsorption and Oxidation Mechanisms over CuCl2-Impregnated Carbonaceous Material Surface

CuCl2-modified carbonaceous materials have been regarded as a kind of mercury sorbent, but the Hg0 reaction mechanism over CuCl2-impregnated sorbent surface is still unclear. In this work, the binding mechanism of Hg0 on CuCl2-impregnated carbonaceous material surface was investigated using hybrid density functional theory (DFT). The results indicate that the dissociation mechanism is responsible for CuCl2 adsorption over carbonaceous material sorbent surface. The active chlorine species generated from CuCl2 adsorption can significantly enhance mercury adsorption over carbonaceous material sorbent surface. Hg0 adsorption over CuCl2-impregnated carbonaceous material surface is dominated by a chemisorption mechanism. Surface Cl and C atoms are identified as the active sites for Hg0 adsorption on CuCl2-impregnated carbonaceous material surface. CuCl2 plays an important role in mercury adsorption on CuCl2-impregnated carbonaceous materials. CuCl2 includes the following roles: (1) CuCl2 can increase the reacti...

Magnetic Porous Carbonaceous Material Produced from Tea Waste for Efficient Removal of As(V), Cr(VI), Humic Acid, and Dyes

Magnetic porous carbonaceous (MPC) materials derived from tea waste were synthesized by an integrated biosorption–pyrolysis process and were applied as adsorbents for wastewater cleanup. On the basis of various characterizations, we demonstrated that the formation mechanism of γ-Fe2O3 anchored on the porous carbonaceous material surface consisted of the adsorption of iron ions and then the γ-Fe2O3 nucleation and growth through pyrolysis at alternative peak temperatures (300–500 °C). The sample pyrolyzed at 300 °C (MPC-300) showed good capacities for As(V) (38.03 mg g–1) and Cr(VI) (21.23 mg g–1) adsorption, outperforming that of commercial bulk Fe2O3 and many other materials. Moreover, the large available positive charge density can facilitate the effective adsorption of anionic dye (MO) and humic acid (HA) on the γ-Fe2O3 surface while the adsorption performance is sluggish for cationic dyes (MB and RhB). Relatively, the adsorption isotherms could significantly conform to the Langmuir model, and the pseud...

Dodecahedron-Shaped Porous Vanadium Oxide and Carbon Composite for High-Rate Lithium Ion Batteries.

Carbon-based nanocomposites have been extensively studied in energy storage and conversion systems because of their superior electrochemical performance. However, the majority of metal oxides are grown on the surface of carbonaceous material. Herein, we report a different strategy of constructing V2O5 within the metal organic framework derived carbonaceous dodecahedrons. Vanadium precursor is absorbed into the porous dodecahedron-shaped carbon framework first and then in situ converted into V2O5 within the carbonaceous framework in the annealing process in air. As cathode materials for lithium ion batteries, the porous V2O5@C composites exhibit enhanced electrochemical performance, due to the synergistic effect of V2O5 and carbon composite.

Effect of Edge-Carboxylation in Graphene Nanoplatelets on the Performance of Electrochemical Energy Storage

Graphene is considered prospective electrode materials for the electrochemical supercapacitor due to their higher surface area, good electronic conductivity, high chemical stability, and wide operating temperature range. The hetero-atom doping and surface functionalization of graphene are also advantageous to enhance the electrochemical active surface area, thermal and electronic conductivity, wettability and ion transport, and stability. The edge-carboxylated graphene nanoplatelets have been used as oxygen-rich efficient counter electrodes for dye-sensitized solar cells. The catalytic activity in graphene may be due to the oxygen containing functional groups (e.g., carboxyls, hydroxyls, epoxides, and carbonyls), achieved by controlling the amount of oxygen functional groups via thermal annealing or acid oxidation. The surface functional groups or heteroatoms can help the adsorption of ions and then improve the hydrophilicity/lipophilicity of the carbon materials, leading to enhanced wettability and facilitated rapid electrolyte ion transport within the micropores. At the same time, the presence of functional groups (e.g., oxygenated groups) on the surface of carbonaceous materials may induce faradaic redox reactions, leading to a 5–10% increase in the total capacitance. Thus, introducing surface functional groups or heteroatoms on the surface of carbon materials appears to be an effective way of improving an electrode’s capacitance. In the present study, we control the degree of carboxylation in the surface of graphene nanoplatelets by thermal and acidic oxidation processes and studied it effects on the performance of electrochemical supercapacitor.

Towards understanding the carbon catalyzed CO2 reforming of methane to syngas

In this paper, a fixed-bed reactor is used to study the influence of different conditions on carbon catalyzed CO2–CH4 reforming. The surface structure and functional groups of carbonaceous material have been characterized through SEM, XPS, XRD, BET and chemical titration before and after the reaction. Studies have revealed that under non-catalytic condition, methane pyrolysis happens first, followed by the gasification reaction between CO2 and carbon deposit produced from the pyrolysis. While with carbonaceous material, CO2 gasification, methane pyrolysis and CO2–CH4 reforming can take place at the same time, with the reforming as the main reaction, CO2 gasification and methane pyrolysis as the side reaction. Catalytic activity varies from one carbonaceous material to another, but their reaction trend is the same on the whole. Those high specific surface area carbonaceous materials show higher catalytic activity. The increase in reaction temperature and residence time of the reforming can improve the conversion of reactant gas. Adjusting the partial pressure of methane can control carbon–hydrogen ratio of the synthesis gas. XPS and XRD characterizations demonstrate that the structural ordering of carbonaceous materials becomes a little messier after the reforming reaction, and the number and content of oxygen functional groups decrease. That means these oxygen functional groups on the surface of carbonaceous materials are involved in the reforming and these groups along with pore structure on the surface are the major factors influencing the catalytic properties. Different oxygen species make the nature of electrical energy on the surface different; the catalytic activity depends on the polarity of oxygen from different species. Those whose polarity is strong have strong activity. The dipole force can be associated with methane in the form of hydrogen bond, so that the material can display strong activity. Those whose polarity is weak have weak activity, the catalytic activity is weak too. The results of chemical titration and XPS characterization show that the oxygen in the anhydride and lactone structures on the surface of carbonaceous materials are active oxygen, and which is the main active component, it can reduce the activation energy of methane dehydrogenation.

Identification, quantification and modification of detonation nanodiamond functional groups

The chemical composition of the detonation nanodiamond (DND) surface has to be unambiguously known in order to use them for specific applications and to develop strategies of functionalization. To this end, the Boehm titration method was here applied to DNDs of different origins subjected to different purification procedures. This method allows the determination of the oxygenated functional groups present on the surface of carbonaceous materials according to their acidity. The DNDs synthesized at the Institut franco-allemand de recherches de Saint-Louis (ISL) and purified through a two-step method were compared to commercial nanodiamonds. This work proves that the nature of the DND functional groups is very dependent on the history of the post-treatment applied to the nanodiamonds during the purification process of the detonation soot. The nanodiamonds synthesized at ISL and commercial nanodiamonds possess 0.81 COOH sites/nm2 and 0.15 COOH sites/nm2, respectively. However, an oxidation treatment, similar to the one performed on the ISL nanodiamonds, applied to the commercial sample, increases the COOH ratio to 0.80 function/nm2. In addition, the existence of lactone sites was pointed out on oxidized samples, indicating the presence of hydroxyl groups on the surface of untreated nanodiamonds. From experimental values and modelling, it was suggested that these functions are located on the edges of the nanodiamond particles.

Sedimentary processes for the geosynthesis of heterocyclic aromatic hydrocarbons and fluorenes by surface reactions

Abstract Laboratory experiments have shown that activated carbon catalyses the reactions of biphenyls (BPs) with surface adsorbed reactants incorporating either S, O, N or methylene, leading to the formation of some common constituents reported in sedimentary organic matter (OM) namely, dibenzothiophene (DBT), dibenzofuran (DBF), carbazole (C) and fluorene (F). A relationship between the % abundance of the hetero element in the kerogen and the abundance of the related heterocyclic compound in the associated soluble OM supports the hypothesis that these reactions occur in Nature. More specific supporting evidence was obtained from the good relationship observed between methyl and dimethyl isomers of the reactant BPs and the methyl and dimethyl isomers of the proposed heterocyclic products. It is suggested that these aromatic compound distributions reported in sediments and crude oils from the Upper Indus Basin (Pakistan) and the Carnarvon Basin (NW Australia) are the result of a surface reactions of compounds with BP rings and surface adsorbed species of the hetero element on the surface of carbonaceous material.

Structure and electrocatalytic properties of the peroxidase-Nafion composite

Morphology of nanostructured composite material “horse-radish peroxidase-Nafion” is studied by using atomic-force microscope. The results of the AFM-measurements are compared with the electrochemical data on the hydrogen peroxide reduction in the presence of the horse-radish peroxidase adsorbed from aqueous solution and from the “horse-radish peroxidase-Nafion” composite. The results of the electrochemical measurements and the AFM-data are in qualitative agreement with each other. It is shown that the co-immobilization of the horse-radish peroxidase and Nafion results in the enzyme strong immobilization on the carbonaceous material surface; cluster-structured composites are formed, in which the horse-radish peroxidase demonstrates high catalytic activity.

Geosynthesis of dibenzothiophene and alkyl dibenzothiophenes in crude oils and sediments by carbon catalysis

Sediment extracts and crude oils have been shown to contain methyl substituted biphenyls and dibenzothiophenes, with isomer distributions suggesting a geochemical relationship between the two compound classes. Laboratory simulation experiments have shown that carbon catalyses the reaction between surface adsorbed sulfur and biphenyl to form dibenzothiophene. Similarly, the methyl substituted biphenyls reacted to yield corresponding methyl dibenzothiophenes. We suggest that the widespread distribution of dibenzothiophene and alkylated dibenzothiophenes in sediments and crude oils is the result of a catalytic reaction of biphenyl ring systems and surface-adsorbed sulfur on the surface of carbonaceous material.

Carbon/Slag Interactions between Coke/Rubber Blends and EAF Slag at 1 550°C

Using the sessile drop approach, interfacial reactions taking place in the slag/carbon region were investigated at 1550°C in a horizontal tube furnace under inert atmosphere (1 L/min Ar). In this study, waste rubber tyres were blended with metallurgical coke, already used as injectant in electric arc furnace (EAF) steelmaking, in different proportions. Off gas analyses and physicochemical properties of the slag have been evaluated and correlated with the carbon/slag interactions. The gaseous emissions from metallurgical coke showed lower concentrations in comparison to the emissions from the coke–rubber blends. With an increase of rubber in the blend, gaseous emissions were enhanced. Significant carbon/slag interactions occurred when coke/rubber blends were used, with associated iron oxide reductions within the slag phase. Higher gas entrapment in the slag was also observed when the rubber partially replaced the coke.High levels of gas generation leads to increased likelihood of convective transport of reactants and products from the carbonaceous material surface due to evolution of gases as a result of slag/carbon interactions. The oxides present in the ash partially dissolve the molten slag, modifying the slag composition. The results have been discussed and correlated with the hydrogen, ash and sulphur contents of the carbonaceous residues as well as with the dynamic changes in slag composition.This study highlights significant differences in the carbon/slag interactions of coke/rubber blends with EAF slag, compared to interaction of coke with the same slag.

Catalytic activity of Pd/CN systems in hydrogenation of styrene

Hydrogenation of styrene was applied as a test reaction to study the catalytic activity of Pd deposited on the surface of carbonaceous materials enriched with nitrogen (CN). The nitrogen content in the support material was found to have a great influence on the degree of styrene conversion to ethylbenzene. In addition, the reaction was carried out in the presence of modified carbonaceous materials acting as catalysts.

Speciation of functional groups formed on the surface of carbonaceous materials modified by NO

Interactions between NO and the surface of carbonaceous materials characterised by different degree of coalification (brown coal and sub-bituminous coal) have been studied by FTIR-PAS in order to identify the nitrogen species formed.

Hydrogen storage in nickel catalysts supported on activated carbon

We have studied hydrogen storage in a commercial activated carbon impregnated with nickel. High-pressure (20–30 bars) hydrogen uptake at room temperature was assessed using a high-pressure volumetric adsorption–desorption system. The properties of the prepared materials were studied by means of N 2 physisorption, X-ray diffraction, transmission electron microscopy, metal surface area, hydrogen temperature programmed reduction and hydrogen temperature programmed desorption. Various factors influencing the level of hydrogen uptake (metal precursor, metal content, method of preparation) were examined and discussed. It is concluded that the hydrogen stored is loosely chemisorbed on the carbonaceous material surface as spilt-over species through H 2 dissociation on the metal phase then migration onto the support. This hydrogen would also be directly adsorbed on carbon acceptor sites induced by H 2 -pretreatment at 623 K. In both cases, the stored hydrogen directly desorbs from the active carbon support.