STUDIES OF ALIZARINE ADSORPTION FROM SOLUTION ON TO ALUMINUM HYDROXIDE GELS

Adsorption results of alizarine from ethanolic solutions on to alumini um hydroxide gels prepared by precipitation in pure and mixed aqueous and ethanolic media are presented. The gels had different specific sur face areas and porous structures resulting from the nature of the solv ent and the thermal treatment. Equilibrium took a long time to be esta blished (about 9 h). In general, the higher the activation temperature of the gel the higher the adsorption capacity. The adsorbed amounts o f alizarine on to the gels increased by increasing the adsorption temp erature. The adsorption could be described equally well by the Freundl ich and the Langmuir equations. Finally, the apparent enthalpy of the adsorption indicated an activated endothermic chemisorption.