Abstract
An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g−1 for catechol aqueous solutions in a range of 20 at 1500 mg·L−1.
Highlights
Catechol, or ortho-hidroxifenol, is used as an antiseptic topic, in photography, in leather dyeing, in tanneries as inhibitor of polymerization, as chemical intermediary, and in many industries as antioxidant.It is used in laboratories for the detection and determination of many ions.Catechol frequently contaminates waste water generated by several industries such as: chemistry, rubbers, dyes, photography, pharmaceutics, cosmetics and oil industry
Because of the adsorption capacity, the compounds earlier mentioned from aqueous solution in activated carbons depend on various factors, of which some depend on the solid nature as the porous network and the chemical surface and others on the solution as the pH effect, the dissolved solute quantity, the presence of other possible adsorbates, besides the ionic force and the morphology of the same [5,6,7,8,9]
The micropore volume was calculated after applying the Dubinin–Radushkevich (DR) equation to the N2 adsorption isotherm, total pore volume was obtained from the amount adsorbed at P/Po 0.99 and the mesopore volume was determined as the difference between these two values
Summary
Ortho-hidroxifenol, is used as an antiseptic topic, in photography, in leather dyeing, in tanneries as inhibitor of polymerization, as chemical intermediary, and in many industries as antioxidant. It is used in laboratories for the detection and determination of many ions. This work seeks to identify the effects of some variables involved in the catechol adsorption process in aqueous solution on activated carbon, between the pH effect and the influence of the reduction and oxidation on the activated carbon surface on the adsorption capacity and a study of the immersion enthalpy variation of the activated carbon [1,2,3,4,5,10,11,12,13,14,15,16,17]
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