Application of carbon adsorbents prepared from the Brazilian pine-fruit-shell for the removal of Procion Red MX 3B from aqueous solution—Kinetic, equilibrium, and thermodynamic studies

Abstract

Activated (AC-PW) and non-activated (C-PW) carbonaceous materials were prepared from the Brazilian pine-fruit-shell ( Araucaria angustifolia) and tested as adsorbents for the removal of Procion Red MX 3B dye (PR-3B) from aqueous effluents. The activation process lead to increase in the specific surface area, average porous volume, and average porous diameter of the adsorbent AC-PW when compared to C-PW. The effects of shaking time, adsorbent dosage and pH on adsorption capacity were studied. PR-3B uptake was favorable at pHs ranging from 2.0 to 3.0 for C-PW and 2.0 to 7.0 for AC-PW. The contact time required to obtain the equilibrium using C-PW and AC-PW as adsorbents was 6 and 4 h at 298 K, respectively. The values of the function error ( F error) of fractionary-order kinetic model was at least 15 times lower than the values obtained with pseudo-first-order, pseudo-second order and Elovich kinetic models, indicating that this kinetic model was better fitted to the experimental results. For equilibrium data the F error values of the Sips isotherm model were at least 4.0 lower than the values of Langmuir, Freundlich, and Redlich-Peterson isotherm models using C-PW and AC-PW as adsorbents. The enthalpy and entropy of adsorption of PR-3B were obtained from adsorption experiments ranging from 298 to 323 K. Simulated dyehouse effluents were used to check the applicability of the proposed carbons for effluent treatment.