Article

Modification of the adsorption properties of high surface area graphites by oxygen functional groups

Department of Chemical Engineering and Environmental Technology, University of Oviedo, Julián Clavería s/n, 33006 Oviedo, Spain
Carbon (Impact Factor: 6.16). 05/2013; DOI: 10.1016/j.carbon.2008.08.025

ABSTRACT The role of the concentration of oxygen functional groups on the surface of commercial high surface area graphite has been studied in this work. For this purpose, two samples of the parent HSAG have been both oxidized with aqueous HNO3 solution and pyrolysed at 900 °C under an He flow, in order to remove surface oxygen groups. TPD results, in agreement with XPS experiments, reveal the existence of oxygen groups on the surface of the parent HSAG, whose concentration increases substantially after the oxidative treatment, whereas they disappear after the thermal treatment. The adsorption of different alkanes, aromatics and chlorohydrocarbons on the three samples were compared. Adsorption capacities were derived from the adsorption isotherms, whereas thermodynamic properties have been determined from chromatographic retention data. Both the capacity and the strength of adsorption decrease after the oxidative treatment of the graphites. For n-alkanes and cyclic compounds, it was demonstrated that the presence of oxygen surface groups affects their interaction in lower extension. In the adsorption of aromatics and double-bonded compounds, the influence of surface functionalization is more pronounced, since the removal of electrons from the π-electron system of the basal planes, weaken these forces.

Download full-text

Full-text

Available from: Salvador Ordóñez, Sep 02, 2015
1 Follower
 · 
197 Views
 · 
110 Downloads
  • [Show abstract] [Hide abstract]
    ABSTRACT: In general, carbon-based materials play a major role in today’s science and technology and are required to advance with better properties to meet new requirements or to replace existing materials. We fabricated rubber composites reinforced with 5-weight% acid-graphite. The structural, mechanical and thermal properties of these composites were studied and compared. XRD studies indicated that the structure of the acid treated pristine-graphite (acid-graphite) did not change that of pristine graphite. Tensile properties of the composites indicated higher modulus, tensile strength and elongation in comparison with composites of pristine graphite, carbon black. Also, the composites were found to be in improving tendency with thermal properties and fatigue properties. The acid-graphite was investigated for surface morphology by scanning electron microscopy (SEM) and defects or purity by Raman spectroscopy. In this article, we discuss the influence of acid-graphite on rubber with high mechanical and thermal properties. Key wordsAcid Graphite-Styrene-butadiene-rubber
    Korean Journal of Chemical Engineering 07/2010; 27(4):1296-1300. DOI:10.1007/s11814-010-0178-7 · 1.24 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Simultaneous removal of heavy metals coupled with high adsorption capacity of an adsorbent material is an ultimate target in industry for the purification of wastewater. A novel adsorbent prepared from an electronic waste-based material has been used for this purpose. The results exhibit very high removal capacities of the adsorbent for both cobalt and nickel in the single-component systems. These capacities have been compared with those of three widely-used industrial adsorbents and it has been shown that the removal capability of this novel material is well above those of the industrial ones. Moreover, the effect of pH has also been explored and it has been shown that the pH value has a drastic effect on the metal removal capacity at pH values lower than 3. Furthermore, a synergistic effect of two metals has been observed and studied in the binary metal system. The results indicate that not only the simultaneous presence of the two metals does not reduce the adsorption capacity, but also enhances their removal from the effluent.Moreover, the adsorption equilibrium modeling for the single and binary systems have been presented and it has been inferred that the Langmuir-type models can fit the single component experimental data, while the binary system can be fitted only by the modified extended Freundlich model.
    Chemical Engineering Journal 07/2013; 228:140–146. DOI:10.1016/j.cej.2013.04.086 · 4.32 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A new process for the treatment of off-gases containing chlorinated pollutants is presented in this paper. The proposed process consists of the adsorption of the chlorinated compound, followed by the regeneration of the spent adsorbent using hydrogen. Therefore, this process gathers the advantages of the conventional adsorption (useful for a wide range of emissions, even those air-diluted) and the catalytic hydrodechlorination (complete destruction of the chlorinated compound, ensuring the absence of oxidized byproduct). Since it is widely accepted that palladium is the most active phase for catalytic hydrodechlorination, this metal was supported on a given adsorbent. Different materials were tested in this work for use as adsorbents in this application (NaX, KL and ZSM-5 zeolites; activated carbons and synthetic clays), using trichloroethene as model compound. Based on their adsorption capacities, measured by temperature-programmed desorption (TPD), KL and NaX zeolites (adsorption capacity of 25 and 30 micromol/g, respectively), as well as an activated carbon (30 micromol/ g), have been selected for preparing the Pd-containing adsorbents (0.5 wt% of Pd). The most selective catalyst for the total hydrodechlorination of the adsorbed chlorinated compound was the KL supported zeolite, showing full selectivity (at a 92% conversion) for total hydrodechlorination in the hydrogen treatment of the saturated material.
    Environmental Science and Technology 04/2009; 43(6):1999-2004. DOI:10.1021/es803226v · 5.48 Impact Factor
Show more