ACTIVATED CARBON PREPARED FROM SOFTWOOD LIGNOCELLULOSIC BIOMASS – OPUNTIA FICUS INDICA CORDS TO REMOVE AN ANIONIC DYE

Abstract

In this work, lignocellulosic biomass, namely, Opuntia ficus indica cords (OFIC), was selected as a renewable resource for the production of activated carbon. The preparation conditions of chemically activated carbon (AC) samples were the following: activation temperature – 600 °C, heating rate – 10 °C min-1, activation time – 60 min, and OFIC/H3PO4 impregnation ratio – 1/2. The properties of OFIC and activated carbon were determined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Boehm’s method, and pHzpc. AC showed heterogeneous surface and acidic characteristics with a pHZPC of 2.61. OFIC and AC were used as adsorbents to remove the anionic dye Red Bemacid (RB) from aqueous solutions. OFIC was used as a reference for comparison with the prepared AC. The results showed that the experimental data fitted very well with the pseudo-second-order nonlinear model of both adsorbents, with 120 min as equilibrium time and the nonlinear isotherm models of three parameters (Sips and Redlich-Peterson isotherms) were selected as the best fitting ones. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic for the AC/RB dye system.