Studies in Formation and Properties of Carbon-Sulphur Surface Complexes. Part VII. Effect of the Complexes on Surface Behaviour of Carbon Blacks

Department of Chemistry, Panjab University, Chandigarh

Manuscript received 5 May 1973; accepted 7 June 1973

Irreversible fixation of sulphur on Mogul-A and Spheron-4 by treatment with sulphur, hydrogen sulphide and carbon disulphide at 600° alters the shape and contents of the water vapour isotherms (35°) indicating a development of porosity and trends for capillary condensation. Additional fixation of sulphur tends to reduce moisture sorption at all r.v.p.'s indicating partial filling of capillary pores and a fall in the available surface area due to a partial coverage of particles with sulphur. The specific surface areas of both the carbon black samples, before and after various fixations of sulphur, were determined from CO₂-isotherms at 0° and pressures upto 200 torr by applying Polanyi potential theory as modified by Dubinin. The values obtained are in harmony with the above views. The catalytic activity of each carbon black increases sharply on fixation of a small amount of sulphur showing that the associated sulphur is combined chemically. The activity, however, starts falling on continued fixation of sulphur, although the value remains in­variably higher than that of the original sample.