Introduction Of Oxygen Functional Groups Research Articles

The Effect of Pretreatment with H2O2 on the Oxidation of Shenfu Subbituminous Coal with NaOCl

Shenfu subbituminous coal (SFSBC) and pretreated SFSBC with H2O2 were subjected to oxidation with NaOCl at 30°C for 5 h. The results show that the pretreatment with H2O2 significantly increased the yields of water-soluble species (WSS), especially benzene carboxylic acids (BCA) and long-chain alkanedioic acids (LCADA), but substantially inhibited the formation of chloro-substituted alkanoic acids. The introduction of oxygen functional groups to SFSBC by the pretreatment (LCADA) could be responsible for the increase in the yields of WSS, especially BCA and LCADA.

Influence of an Oxygen Functionalization on the Physicochemical Properties of Ionic Liquids: Density, Viscosity, and Carbon Dioxide Solubility as a Function of Temperature

The physicochemical properties (density, viscosity, and carbon dioxide solubility) of ionic liquids based on pyridinium, pyrrolidinium, and ammonium cations were studied at atmospheric pressure and as a function of temperature between (293 and 343) K. The influence of the inclusion of oxygen functional groups (hydroxyl and ester) in the cations was assessed by comparing their behavior with that of similar nonfunctionalized ionic liquids. We observed that the presence of oxygen groups does not affect the density significantly. The inclusion of an ester group in the alkyl-side chain of pyridinium or ammonium cations greatly increases the viscosity of bis(trifluoromethylsulfonyl)imide ionic liquids (5 times for pyridinium, 2 times for ammonium-based ionic liquids at 293 K), while the presence of hydroxyl groups only slightly increases their viscosity (16 % increase for ammonium at 293 K). Carbon dioxide solubilities are not significantly influenced by the introduction of oxygen functional groups in the catio...

Effect of O2Plasma Treatments of Carbon Supports on Pt-Ru Electrocatalysts

In the present study, carbon supports mixed with purified multi-walled carbon nanotubes (MWNTs) and carbon blacks (CBs) were used to improve the cell performance of direct methanol fuel cells (DMFCs). Additionally, the effect of <TEX>$O_2$</TEX> plasma treatment on CBs/MWNTs supports was investigated for different plasma RF powers of 100, 200, and 300 W. The surface and structural properties of the CBs/MWNTs supports were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and inductive coupled plasma-mass spectrometer (ICP-MS). The electrocatalytic activity of PtRu/CBs/MWNTs catalysts was investigated by cyclic voltammetry measurement. In the experimental results, the oxygen functional groups of the supports were increased with increasing plasma RF power, while the average Pt particle size was decreased owing to the improvement of dispersibility of the catalysts. The electrochemical activity of the catalysts for methanol oxidation was gradually improved by the larger available active surface area, itself due to the introduction of oxygen functional groups. Consequently, it was found that <TEX>$O_2$</TEX> plasma treatments could influence the surface properties of the carbon supports, resulting in enhanced electrocatalytic activity of the catalysts for DMFCs.

Plasma Surface Modification of Poly(aryl ether ether ketone) and Surface Metallization using Copper Metal

The surface of poly(aryl ether ether ketone) (PEEK) was modified using oxygen plasma treatment to improve the adhesive strength at Cu/PEEK interfaces. It is well known that plasma treatment results in etching and introduces functional groups to polymer surfaces. The effect of plasma treatment methods, which were ordinary plasma treatment and pulsed plasma treatment, on the adhesive strength was evaluated. The following three points were revealed; (1) oxygen plasma treatment enhanced the adhesive strength at Cu/PEEK interfaces; (2) oxygen plasma treatment introduced oxygen functional groups and produced an etching action at the interfaces. This etching action certainly contributed to the adhesive strength among these actions; (3) introduction of oxygen functional groups might also produce a synergetic effect with an etching action and this might result in stronger adhesion.

Effect of Irradiation Power on Surface Modification of Polyester by Ammonia Plasma Treatment

The power dependence of nitrogen functional group introduction treated with ammonia plasma on poly(ethylene terephthalate) (PET) and liquid crystal polymer (LCP) was investigated. The ratios of NH2 and N–C=O groups, which are the introduced functional groups, differ depending on the power used for plasma generation. The ratio of N–C=O groups increases with increasing power. For PET, the introduction of oxygen functional groups occurs at low power. Power dependences of contact angles were found for PET and LCP. They are related to the different types and quantities of functional groups with respect to the power. A considerable decrease in contact angles is apparent at the low-power side of 0–15 W.

Surface Modification of Polymer Films by Pulsed Oxygen Plasma

The surfaces of three kinds of polymer were treated using pulsed oxygen plasma: poly(ether ether ketone) (PEEK), liquid crystalline polymer (LCP), and linear-low-density polyethylene (L-LDPE). Also using pulsed oxygen plasma, oxygen functional groups were introduced on polymer surfaces. The effects of oxygen functional group introduction were investigated to elucidate whether any differences exist in the manner of introduction of oxygen functional groups on the polymer surface, arising from differences in polymer structures. The introduction of oxygen functional groups formed hydrophilic polymer surfaces. Fewer oxygen functional groups were introduced on PEEK and LCP surfaces by pulsed plasma treatment than by continuous oxygen plasma. On the other hand, many oxygen functional groups were introduced on L-LDPE surfaces than by continuous oxygen plasma. Reasons for different attachment of oxygen functional groups by pulsed oxygen plasma processing on polymer surfaces were discussed.

Removal of Electrolytes from Dilute Aqueous Solutions Using Activated Carbon Electrodes

The removal of electrolytes from aqueous solutions and cyclic operation were carried out using a small size flow through capacitor apparatus. The operation condition of the apparatus which are voltage, flow rates of solution and form of carbon electrode are determind. The effect of the characteristics of activated carbons on removal of various kinds of surfates electrolytes were discussed by using 9 kinds of activated carbons which were orginated from different raw materials. It is suggested that specific surface area of activated carbons contributed siginificantly to the removal of ions. Introduction of oxygenfunctional groups on the activated carbons promotes the amount of ion removal. It was recognized that it showed a tendency of removal as much as sulfates whose ion radius was small. In the case of cyclic operation, the electrodes are discharged or short-circuited at some point, adsorbed ions are desorped and the electrode is regenerated.

Effects of surface and structural properties of carbons on the behavior of carbon-supported molybdenum catalysts

Previous work on carbon-supported hydrodesulfurization (HDS) catalysts has led to the general realization that the nature of the support has a very significant influence on catalytic activity. The present investigation attempts to provide a more focused understanding of the exact nature of this influence. Mostly one support, a commercial carbon black, was subjected to oxidative and/or thermal treatment to modify its surface and structural properties. These were thoroughly examined using temperature-programmed desorption, X-ray diffraction, titrations, and electrophoresis. The various carbon-supported molybdenum catalysts were prepared by equilibrium adsorption and incipient wetness impregnation using four different catalyst precursors. The catalytic activity in thiophene HDS and Fischer-Tropsch synthesis was determined in fixed-bed flow reactors connected on-line to gas chromatographs. The catalysts were characterized by X-ray photoelectron spectroscopy. The heretofore mostly neglected knowledge of carbon surface chemistry was shown to provide the necessary framework for the understanding of the variations in catalytic activity. It is concluded, however, that two conflicting requirements complicate the preparation of highly active (i.e., highly dispersed) molybdenum species on carbon surfaces. On one hand, the introduction of oxygen functional groups provides anchoring sites for catalyst precursor adsorption and thus the potential for its high initial dispersion. On the other hand, this also renders the support surface negatively charged over a wide range of pH conditions. At very low pH conditions, below the isoelectric point of the support, when the attractive forces prevail between the Mo anions and the positively charged carbon surface, Mo polymerization is thought to contribute to catalyst agglomeration. Final catalyst dispersion (i.e., catalytic activity) is also influenced by the thermal stability of the oxygen functional groups on the carbon surface. No significant correlation between structural parameters of the support and catalytic activity was found.