Abstract

NAVARRETE, Luisa Fernanda; GIRALDO, Liliana  and  MORENO, Juan Carlos. THE INFLUENCE OF SUPERFICIAL CHEMISTRY IN THE IMMERSION ENTHALPY OF ACTIVATED CARBON IN AQUEOUS SOLUTIONS OF PHENOL AND 4-NITROPHENOL. Rev.Colomb.Quim. [online]. 2006, vol.35, n.2, pp.215-224. ISSN 0120-2804.

The interactions between five samples of activated carbon with different activation grades (~20%, obtained from different lignocellulose’ s materials) and aqueous solutions of phenol and 4-nitrofenol were studied by determining the values of the immersion enthalpy. From this study, it is established that the activated carbons exhibit a basic character and show values for the point of zero charge (PZC) between 7.4 and 9.7; also, the total basicity content is greater in all cases than the value obtained for the total acidity. The immersion enthalpy values of the activated carbons in NaOH and HCl solutions were determined, yielding larger values in the case of HCl which are between 32.6 -68.3 Jg^-1. The inmersion enthalpy values in phenol solution range between 7.6 y 13.9 Jg^-1 and for 4-nitro fenol between 12.7 y 20.5 Jg^-1; all the samples displayed greater values after immersion in the second compound.

Keywords : Adsorption of phenols; acidity and basicity; immersion calorimetry; pH_PZC; immersion enthalpy.

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