Abstract

PERALTA ARROYO, Jacqueline; SUN KOU, María del Rosario  and  BENDEZU MONTES, Salvador. Preparation, characterization of activated carbons with KOH and H₃PO₄ and application in Cd(II) Adsorption. Rev. Soc. Quím. Perú [online]. 2008, vol.74, n.4, pp.219-232. ISSN 1810-634X.

Activated carbons were prepared from eucalypt (Eucalyptus globulus Labill), a plenty species in Cajamarca (North of Peru). The materials showed good adsorbent capacity to remotion of Cd(II). Activation chemical with KOH and H₃PO₄ was used to prepare the adsorbents. To activation chemical with KOH was used 6 different ratios of impregnation in mass (impregnant agent/precursor): 0,25; 0,50; 0,75; 1,00; 1,50; 2,00 and 3 different activation temperature: 500, 600 y 700°C. Chemical activation with H₃PO₄ was used 3 ratios of impregnation: 0,50; 1,00 y 1,50 and 3 temperatures: 400, 500 y 600°C. Best conditions to KOH were: ratio of impregnation 1,00 to 600°C; and for H₃PO₄ were: ratio of impregnation of 1,00 to 400°C. The physic-chemical characterization was made with FTIR, SEM and AA.There were studied the parameters that affect the process of adsorption of Cd(II): time of contact and pH. Additional there were obtained the isotherms of adsorption, which experimental information was correlated by the models of Langmuir and Freundlich. The kinetic of adsorption of Cd(II), was studied using the kinetic models: the pseudo-first and pseudo-second order. The best conditions of activation with KOH were: reason of impregnation of 1,00 and 600ºC; a maximum adsorption of Cd(II) being achieved 65,48 mg of Cd(II) by gram of carbon. In the same way with H₃PO₄ the ideal conditions were: reason of impregnation of 1,00 and 400ºC, there being achieved a maximum capacity of adsorption of 36,92 mg of Cd(II) by gram of carbon. The ideal parameters of adsorption were: about pH 6 and relation of 1 gram of carbon/Lof solution. From the kinetic study determined that the time of equilibrium of the process of adsorption of Cd(II), for activated carbon prepared with H₃PO₄ was 60 minutes and for KOH was 120 minutes. In all the cases, the kinetic model who explains better the process of adsorption was of the pseudo-second order, while for the isotherms of adsorption, the experimental information adjusted better to the model of Langmuir.

Keywords : Adsorption of cadmio; water treatment; activated carbon; chemical activation with KOH and H₃PO₄.

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