Chemisorption of Oxygen by Graphon on Various Treatments

Department of Chemistry, Panjab University, Chandigarh-160014

Manuscript received 6 March 1974; accepted 23 September 1974

Chemisorption of oxygen on Graphon, a highly graphitised carbon black, on treatment with oxygen (400^°), ozone (in water and carbon tetrachloride at ordinary temperature), hot conceu­trated nitric acid and oxidising solutions of ceric sulphate, potassium persulphate and hydrogen peroxide are reported. The surface covered by the oxygen, on various treatments, varies between 2.5 and 13.8 m²/g., before pre-activation and between 6.3 and 21.9 m²/g., after pre-activation of Graphon to 17.2 per cent burn-off. The B.E.T. (nitrogen) surface area of Graphon increases from 76 m² to 98 m²/g., on activation; the maximum surface coverage by oxygen, therefore, corres­ponds to about 18 per cent before and 22 per cent after the burn-off. The chemisorbed oxygen comes off largely as carbon dioxide and to a much smaller extent as carbon monoxide. The pre­sence of oxygen imparts acidity to the surface which, however, is not equivalent to the amount of CO₂-complex formed. The presence of oxygen imparts hydrophilicity to the surface although it does not alter benzophilicity of the surface to any noticeable extent.