INFLUENCIA DEL pH SOBRE LA ADSORCIóN EN CARBóN ACTIVADO DE Cd(II) Y Ni(II) DESDE SOLUCIONES ACUOSAS

the cd (ii) and ni(ii) ions adsorption from aqueous solutions on activated carbon is studied to different values of ph. the ions adsorption is carried out under two conditions of ph solution: in the first one, the ph changes in the course of the process as the ions are adsorbed; in the second one, the ph is kept fixed during the adsorption. when the solution is not controlled, the hydronium ions concentration increases, reaching a maximum value around a ph of 4, for both ions, whose values are of 346 mmolml-1 for the case of the adsorption of cd (ii) and of 436 mmol.ml-1 for ni(ii). for all the ph values and the two conditions of the adsorption process, much more quantity of ni (ii) is adsorbed with values between 0.04 and 0.42 mmol.g-1, while for the cd (ii) the maximum amount adsorbed is 0.16 mmol.g-1. the increase of the hydronium ions in the cd(ii) and ni(ii) solutions, in which the value of the ph is not controlled, helps the process of adsorption, while keeping ph fixed in the solution, ions are adsorbed in a less quantity.