Ni(II) and Cd(II) simple and competitive adsorption on activated carbon oxidized. influence of the oxidant agents H2O2 and NaClO

Abstract

Granular activated carbon, GAC, modified by oxidation with H2O2 and NaClO aqueous solutions and heat treatment at 900 °C. The N2 adsorption isotherms at −196 °C and SEM and FTIR results were used to characterize the properties of the prepared ACs. Textural parameters such as BET surface area and pore volumes were assessed by gas adsorption. The BET surface area values of solids are between 687 and 876 m2g-1. Additionally immersion enthalpies of activated carbons in benzene, water, hydrochloric acid and sodium hydroxide solutions and Ni(II) and Cd(II) solutions of 500 mgL-1 were determined, with values between 32 and 145 Jg-1. Ni(II) and Cd(II) adsorption isotherms were determined at pH 6 on activated carbons and competitive adsorption tests were realized between the two ions. The results show that for the tests carried out, the adsorption capacity decreases when the content of chemical groups on the surface also decreases. Finally, the experimental results of the adsorption from solution were adjusted to the Langmuir and Freundlich models and a better fit with the first was found. With maximum adsorption capacities values for Ni(II) between 3.99 and 64.9 mgg-1 for Cd(II) between 2.61 and 55.2 mgg-1. Values for competitive adsorption ions present in solution, Ni(II) and Cd(II), on the activated carbons, diminishes compared to those obtained in simple adsorption, this indicates the effect of the an ion competitive presence in adsorption another.