Producing adsorbents from sewage sludge and discarded tyres

Adsorbent materials have been produced from sewage sludge and discarded tyres. Their physical structures and chemical surfaces differ according to their origin and production process. However, all the activated carbons show a good development of their mesopore structure. The adsorption equilibriums of methylene blue and sandolan brilliant red N-BG 125 (an industrial dye) onto the activated carbons generated have been analysed and described in terms of Freundlich isotherm. The best adsorption results were those corresponding to sandolan brilliant red onto the adsorbent obtained from sludge chemically activated with ZnCl2. The effect of temperature on the dyes adsorption was addressed and the thermodynamic parameters (ΔH, ΔS and ΔG) were determined for each of the studied systems. It was found that the process was endothermic and spontaneous in all cases.