Types Of Oxygen-containing Groups Research Articles

Influence of pre-oxidization on the characterizations of coal gasification fine slag-derived activated carbons for CO2 capture

Coal gasification fine slag (FS)-based activated carbons (ACs) for CO2 capture provided a new method to realize the value-added utilization of FS. Furthermore, pre-oxidation treatment of carbonaceous materials is one of the most efficient possibilities to obtain developed pore structure of activated carbons to enhance the CO2 adsorption capacity. In this study, four types of oxidizing agents (HNO3, NaClO, H2O2, and air) carefully modified the coal gasification fine slag residual carbon (RC) to fix the oxygen content at about 12 wt%, 15 wt%, and 18 wt%. The samples were characterized by XPS, volumetric sorption analyzer, SEM, Raman spectroscopy, TEM, TG, and TGMS. Results suggested that the specific surface area and total pore volume of the ACs were observed to increase after oxidation. The types of oxygen-containing groups also affected the pore structure of the ACs. The results showed that the content of OCO groups were the most predominant factors for high surface area, and the CO group could hinder the development of pore structure. The ACs facilitated by RC oxidation by HNO3 had a high CO2 storage capacity of 12.4 % at 30 °C and a fast adsorption rate, around 86 % of CO2 uptake occurring in a span of 1 min.

Preparation and aggregate state regulation of co-assembly graphene oxide-porphyrin composite Langmuir films via surface-modified graphene oxide sheets

Constructing graphene oxide (GO)-based 2D nanomaterials via facile and appropriate methods have aroused much attention due to their potential applications in many fields. Herein, by Langmuir-Blodgett (LB) technique, we have successfully fabricated GO-based films composited with porphyrin molecules. By the reaction of diazotization and Fischer osazone, different surface states of GO sheets with sulfonate groups were obtained. The amphiphilic GO and surface modified GO sheets could spontaneously form composite films at the air/water interface with porphyrin molecules (TMPyP) by electrostatic interactions and π-π stacking. Since the sheets can perfectly float on the interface, the TMPyP molecules were adsorbed on the floating-layers and self-assembled into highly ordered J-aggregate structures. The morphological characterization results showed the composite films with smooth and dense surface. Due to the different surface state of the nanosheets, the aggregate states of porphyrin molecules were different which could be demonstrated in the UV–vis spectra. The results indicated that the induction of sulfonate groups and the types of oxygen-containing groups have played important roles for regulating the aggregate state of porphyrin molecules.

Effects of activation temperature on the deoxygenation, specific surface area and supercapacitor performance of graphene

This paper systematically studies the influence of temperature during KOH activation of graphene on quantities and types of oxygen-containing groups, pore structure, specific surface area, and performance of supercapacitor. The changes of the amount and types of oxygen-containing functional groups were observed with the aid of Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy. The pore structure and specific surface area were characterized by means of X-ray powder diffraction, N2 adsorption-desorption and transmission electron microscopy. Electrochemical properties were assessed by cyclic voltammetry, electrochemical impedance and galvanostatic charge-discharge. As the temperature increased, the oxygen content of activated graphene decreased, while its specific surface area increased. The specific capacitance of the activated graphene first increased and then decreased with a maximum (326 F/g) at 400 °C. When the temperature was 800 °C, the surface area of the material peaked (3269 m2/g), and the specific capacitance was 204 F/g.

Changes of oxygen-containing groups during thermal treatment and their influences on moisture readsorption of lignite

ABSTRACTThe changes in oxygen-containing groups in the thermal treatment process of lignite were analyzed and the moisture readsorption amounts of upgraded coals were related in this study. A chemical titration method was applied to determine the types and contents of oxygen-containing groups in raw lignite and upgraded coals obtained in the temperature range of 353–633 K under atmospheres of argon, air, and carbon dioxide. Experimental results showed that the oxygen-containing groups mainly involved carbonyl, phenolic hydroxyl, and carboxylic groups (including carboxyl and carboxylate), among which phenolic groups were dominant. These different oxygen-containing groups decomposed discriminatingly with temperature according to thermal stability. The removal of oxygen-containing groups proceeded more easily in a CO2 atmosphere compared to in Ar. The oxidation reaction occurring on the surface of lignite exposed to air led to an increase in oxygen-containing groups. The different types of oxygen-containing groups possessed various combining abilities with water, among which carboxyl was considered the most important group for the moisture readsorption. Decomposition of oxygen-containing groups in the thermal treatment process of lignite mainly caused a reduction in monolayer water adsorption and further decreased the multilayer water.

Selectivity tailoring of Pd/CNTs in phenol hydrogenation by surface modification: Role of C[sbnd]O oxygen species

The effect of different types of oxygen containing groups (OCGs) on the catalytic performance was investigated in this paper by performing the selective hydrogenation of phenol in aqueous phase over the carbon supported Pd catalysts. The type of OCGs on carbon nanotubes (CNTs) was regulated by pretreating it with HNO3, or HNO3 followed by hydrothermal or thermal oxidation treatment. A distinct difference in the amount of phenolic/ether groups (CO) was observed for CNTs treated by different methods, while the difference in the amount of carbonyl groups (CO) and carboxylic groups was much smaller. The results showed that the selectivity to cyclohexanone decreased with the increase of CO amount on carbon surface. CO groups played an important role in adsorption/desorption behavior of phenol/cyclohexanone and was considered to be responsible for the dramatic selectivity difference.

Characterization and dispersion of carbon spheres modified by HNO3/H2O2 oxidization in water

Carbon spheres (CSs) were modified by a mixture of HNO3 and H2O2 with different volume ratios and concentrations to improve their dispersability in a liquid. The morphologies and microstructures of the modified CSs were characterized by field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry and acid–base titration. Results show that the amount and types of oxygen-containing groups can be tuned by the concentration and ratio of HNO3/H2O2.HNO3favors the formation of carboxyl and carbonyl groups while H2O2 introduces mainly hydroxyl. The amount of oxygen-containing functional groups increases with the concentration of the oxidants when the volume ratio of HNO3/H2O2 is 1, which is as high as 2.164 mmol/g when the concentrations of HNO3 and H2O2 are 16 and 8.8 M, respectively. The resulting CSs have a remarkable dispersability and stability in water. [New Carbon Materials 2013, 28(3): 228–234]

A thermodynamic approach to assess organic solute adsorption onto activated carbon in water

In this paper, the hydrophobicity of 13 activated carbons is determined by various methods; water vapour adsorption, immersion calorimetry, and contact angle measurements. The quantity and type of oxygen-containing groups on the activated carbon were measured and related to the methods used to measure hydrophobicity. It was found that the water-activated carbon adsorption strength (based on immersion calorimetry, contact angles) depended on both type and quantity of oxygen-containing groups, while water vapour adsorption depended only on their quantity. Activated carbon hydrophobicity measurements alone could not be related to 1-hexanol and 1,3-dichloropropene adsorption. However, a relationship was found between work of adhesion and adsorption of these solutes. The work of adhesion depends not only on activated carbon–water interaction (carbon hydrophobicity), but also on solute–water (solute hydrophobicity) and activated carbon–solute interactions. Our research shows that the work of adhesion can explain solute adsorption and includes the effect of hydrogen bond formation between solute and activated carbon.

Effect of Nitric Acid Pretreatment on the Properties of Activated Carbon and Supported Palladium Catalysts

The activated carbon was pretreated with different concentrations of HNO3 (from 0.5 to 67%). The amount and type of oxygen-containing groups on the activated carbon were determined with the adsorption neutralization method and temperature-programmed desorption (TPD) of CO and CO2; furthermore, the density of total acidity (DTA) has been proposed. The Pd particle size of Pd/C catalysts was measured by X-ray diffraction patterns (XRD), CO chemisorption, and TEM. The experimental results indicated that the amount of oxygen-containing groups and the total acidity on the activated carbons, the Pd particle size and catalytic activity of Pd/C catalysts are highly dependent upon the HNO3 concentration used in the pretreatment. The pretreatment of activated carbon with a low concentration of HNO3 can increase the structure parameters due to removal of the impurities, will be beneficial to create an appropriate DTA environment, and will further improve the Pd dispersion and the catalytic activity of Pd/C catalysts....

Simulation Study of the Effect of the Chemical Heterogeneity of Activated Carbon on Water Adsorption

In this paper we present results from the molecular simulation of water adsorption in slit-shaped activated carbon pores. We calculate adsorption isotherms by grand canonical Monte Carlo (GCMC) simulation, Henry's constants by Monte Carlo integration, and vapor−liquid equilibrium data by the gauge-cell Monte Carlo method, to investigate the chemical heterogeneity of activated carbon adsorbents. Several types of polar oxygen-containing sites are placed on the surface of the carbon with different densities and local distributions, in order to determine the individual effects of each of these factors on the adsorption of water. Our results confirm the role of surface sites in the enhancement of water adsorption. Furthermore, we show that the local distribution of these sites has a strong effect on low-pressure adsorption, while the overall site density affects mainly the vapor−liquid phase transition. The type of oxygen-containing group is shown not to be of critical importance, since more complex groups can...

Structural changes of a pyrolytic graphite surface oxidized by electrochemical and plasma treatment

Pyrolytic graphite (PG) surfaces have been oxidized by electrochemical and oxygen plasma treatment. The oxidized PG surfaces have been studied by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared attenuated total reflection spectroscopy (FT-IR-ATR). Oxidation caused by the plasma treatment results in a small increment of the oxygen: carbon (O/C) ratio, compared to electrochemical treatment. Moreover, the increment of the O/C ratio for the plasma treated edge surface is smaller than that for the plasma treated basal surface. A steep gradient in oxygen concentration exists within the edge subsurface of PG for samples subjected to severe electrochemical treatment, as compared to those samples subjected to plasma treatment. For the electrochemical treatment, carbonyl, carboxyl, ester and lactone groups are introduced to the edge surface following relatively severe treatment. The ratio of ester and lactone groups to carboxyl groups increases with the extent of electrochemical treatment. For plasma treated samples, other types of oxygen-containing groups, which are probably keto-enol groups, are added to the edge surface, unlike during electrochemical treatment.

The œstrogenic activity of some condensed-ring compounds in relation to their other biological activities

The very rapid progress which has been made recently in the chemistry of the œstrogenic hormones, of which an excellent has been given by Girard (1933) has established that these substances are hydrogenated phenanthrene derivatives containing oxygen in the molecule ( cf . Butenandt, Weidlich, and Thompson, 1933). On the assumption of a biological relationship between these hormones and the sterols and bile acids, an assumption which seems justifiable, although it cannot yet be regarded as rigidly proved, œstrone (= ketohydroxyœstratriene) is probably represented by formula I or II. The present communication describes the examination for œstrogenic properties of a number of condensed carbon-ring compounds of somewhat analogous structure in an attempt to elucidate the molecular conditions necessary for œstrogenic activity. A preliminary account of some of these experiments has already been given (cook, Dodds, and Hewett, 1933; cook and Dodds, 1933). Our investigations have brought to light a number of pure synthetic compounds, of known molecular structure, which show this physiological activity, and in some of the compounds studied the activity is of a very high order. It will be observed that one of two oxygen atoms in œstrone is ketonic and the other hydroxylic. Girard (1933) has suggested that these two types of oxygen-containing groups are biologically equivalent, and our own experiments group but no hydroxyl group, whereas others contain only hydroxyl groups in a similar type of molecule.