Preparation, characterization, and application of low-cost acai seed-based activated carbon for phenol adsorption

Activated carbon (AC(Acai)) was obtained from the activation of acai seeds at 800 degrees C under CO2 flow. The surface groups of the material were determined by Boehm titration and information about surface charge was obtained using the methodology of the point of zero charge (PZC). Boehm titration and PZC tests showed that the AC(Acai) sample has a basic character. The optimum pH range for the adsorption process is 3.5-8 and the optimum dosage is 0.1 g/50 mL of phenol solution. AC(Acai) has a surface area of 496 m(2) g(-1) and pore volume of 0.217 cm(3) g(-1) . The adsorption kinetics follows the pseudo-second-order model. The Langmuir isotherm model satisfactorily described the experimental data. The maximum adsorption capacity obtained was of 133 mg g(-1) at 25 degrees C. Deionized water, NaOH solution (0.1 M), and ethanol were used as desorption agents, but none of them showed promising results for the regeneration of AC(Acai). The thermodynamic studies show that the adsorption process is exothermic, spontaneous, and favorable.