PREPARAÇÃO E CARACTERIZAÇÃO DE CARVÃO ATIVADO QUIMICAMENTE A PARTIR DE SERRAGEM DA MADEIRA DE PINUS ELLIOTTII E APLICAÇÃO NA ADSORÇÃO DO CORANTE REMAZOL AMARELO OURO

Abstract

The purpose of this work was to produce activated carbon from the sawdust of Pinus Elliottii (PS) (Pine Sawdust), a residue of the timber industry, by chemical activation using H3PO4 and ZnCl2. It was also applied a fractional factorial design to evaluate the influence of variables in the preparation of activated carbon: activating agent H3PO4 and ZnCl2, impregnation ratio (70% and 150%), activation temperature and activation time, using as response the adsorption of the dye RAO (Remazol Yellow Gold). The characterization of the samples was made by SEM analysis (scanning electron microscopy), Zeta potential, pH of zero charge point, Boehm titrations, Absorption Infrared Spectroscopy, DSC / TG and BET. A study of the adsorption of RAO dye was made using as adsorbent the prepared activated carbon sample, which showed better potential to adsorb this dye. It was applied the response surface methodology (RSM) to analyze the effect of the variables pH, Ionic Strength, agitation rate and adsorbent dosage, as well as to optimize the methodology for maximum adsorption of the dye RAO. It was performed an adsorption equilibrium study at temperatures of 298, 308, 318 and 328 K, in which were applied Langmuir, Freundlich, Dubinin-Radushkevich and Temkin models. The optimum conditions for preparation of activated carbon, obtained by fractional factorial design were: impregnation ratio of 150%, temperature 600ºC, heating time of 2 h and ZnCl2 as activating agent. The optimum conditions for the RAO dye adsorption by the activated carbon obtained by RSM were: pH = 10.0, Ionic Strength = 0.4 mol Lˉ¹, agitation rate = 200.0 rpm and adsorbent dosage= 0.025 g .The Langmuir isotherm model was the best correlated for the experimental data and the highest value of adsorption (611.4 mg gˉ¹) was found on temperature of 328 K; the values of adsorption`s enthalpy and entropy were obtained: 16.967 kJ moLˉ¹ and 137.342 J K-1 moLˉ¹, respectively. Through this study it was found that the activated carbon has great potential for dye adsorption and can be used in the treatment of textile effluents.