Activated carbons from sewage sludge: Application to aqueous-phase adsorption of 4-chlorophenol Original Research Article

Activated carbons of different characteristics have been prepared from dried sewage sludge using CO2, air and KOH as activating agents. The adsorption capacity of the resulting materials has been checked using 4-chlorophenol as a target compound in aqueous solution. CO2 and air-activation led to carbons of low BET area which increased with the activation temperature but did not reach 100 m2/g at the best. The high ash content of the starting material (23%, d.b.) limits the development of porosity since the partial gasification does not affect the inorganic matter. In the case of air-activation, the resulting surface remains fairly low even in ash-free basis, reaching no more than 250 m2/g.