PERGAMON Carbon 38 (2000) 345–353 Electrochemically oxidised graphite. Characterisation and some ion exchange properties a a, b c * ¨ John W. Peckett , Philippe Trens , Regis D. Gougeon , Andreas Poppl , Robin b a K. Harris , Michael J. Hudson a Department of Chemistry, University of Reading, P .O. Box 224, Whiteknights, Reading, Berkshire, RG66AD, UK b Department of Chemistry, University of Durham, South Road, Durham, DH13LE, UK c ¨ ¨ ¨ Fakultat f ur Physic und Geowissenschaften, Universitat Leipzig, Leipzig, Germany Received 12 October 1998; accepted 30 April 1999 Abstract An evaluation of some of the properties of electrochemically oxidised graphite has been carried out. These studies include textural characterisation, magic angle spinning NMR, ESR and ion exchange properties. A study of the surface morphology has also been carried out using high-resolution transmission electron microscopy and identification of surface groups confirmed by FTIR spectroscopy. The electrochemical method of preparation is shown to confer, to the porous graphite oxide obtained, different surface chemical groups that can be used for ion exchange purposes. ESR shows that Cu(II) is coordinated to the oxidised graphite.  2000 Elsevier Science Ltd. All rights reserved. Keywords: A. Graphite; B. Oxidation; C. Adsorption; D. Porosity 1. Introduction The materials studied here were within the size range of 60 to 700 mm. FTIR spectroscopy of the electrochemically There is a renewed interest in carbons, mainly due to the oxidised graphite showed the presence of hydroxyl groups, discovery of new shape or new carbon-based materials e.g. ketonic groups and double bonds with the material having carbon nanotubes or fullerenes [1,2]. Indeed, carbon is a a significant cation exchange capacity. Some new carbon very versatile material because it has been used for a long adsorbents have been synthesised recently for the selective time under different morphologies, as filters, adsorbents, removal of chromium and other metal cations from aque- catalytic supports, chromatographic supports, or mineral ous solution [14]. In order to compare the activity of our additives [3–7]. The preparation of functionalised pow- oxidised graphite with those results, the removal of Fe(III) dered carbons for these applications by electrochemical from water was also investigated. By using ESR, studies means has been known for some considerable time, were made on the Cu(II)-exchanged oxidised graphite. although the morphology and chemistry of the materials have not been extensively investigated [8–10]. Photoelec- tron spectroscopy of chemically oxidised graphite has 2. Experimental confirmed that there are carboxyl, phenolic hydroxyl and carbonyl groups at or near the surface of the materials [11]. 2.1. Preparation of electrochemically oxidised graphite The accepted structure of the chemically oxidised graphite shows the presence of hydroxyl groups, epoxy groups and The graphite used in the following study was of reactor double bonds [12]. Other workers have shown that it is grade quality and supplied by AERE Harwell. Sulphuric possible to prepare colloidal oxidised graphite by the acid (1 M) was electrolysed between a graphite anode, ca. 21 controlled electrolysis of a suitable electrolyte e.g. double 435320 cm , and a platinum cathode at a current 22 deionised water, dilute sulphuric acid or dilute ethanoic density of ca. 0.5 A cm at 12 V DC. The graphite anode acid [13]. fragmented at the surface during the electrolysis and the electrochemically oxidised graphite, which collected below *Corresponding author. the anode, was periodically removed from the electrolysis 0008-6223 / 00 / $ – see front matter  2000 Elsevier Science Ltd. All rights reserved. PII: S0008-6223(99)00110-4