Resumo

VARGAS, Diana P.; GIRADO, Liliana  e  MORENO, Juan Carlos. DETERMINATION OF ADSORPTION ISOTHERMS AND IMMERSION ENTHALPIES OF ACTIVATED CARBON IN 3-CLORO PHENOL AQUEOUS SOLUTIONS AT DIFFERENT pH. Rev.Colomb.Quim. [online]. 2010, vol.39, n.1, pp.121-130. ISSN 0120-2804.

The effect that produces the solution pH in the adsorption and the immersion enthalpy of an activated carbon in 3-chloro phenol aqueous solutions are studied. The activated carbon presents a surface area of 685 m²g^-1, major acid total groups content and a pH in the point of zero charge, lightly acid. The pH values at which the adsorption isotherms and immersion enthalpies were realized are 3, 5, 7, 9 and 11. The results of the adsorption are fitted to the Langmuir model and the values of the maximum quantity adsorbed that are between 96.2 and 46.4 mgg^-1 were obtained for each pH value and values between 0.422 and 0.965 Lmg^-1 for the Langmuir constant. The maximum quantity adsorbed diminishes with pH, a similar behavior is obtained with regard to the immersion enthalpies; the maximum value for these properties is for pH 5. The immersion enthalpies of the activated carbon in a 3-chloro phenol solution of constant concentration are determined for the different pH values, with a maximum value of 37.6 Jg^-1 for pH 5. Immersion enthalpies of the activated carbon in function of 3-chloro phenol solution concentration are determined at pH 5, of maximum adsorption, and the maximum immersion enthalpy is calculated, with a value of 41.67 Jg^-1.

Palavras-chave : adsorption in solution; activated carbon; 3-chloro phenol; immersion enthalpy.