Sawdust-based activated carbon ability in the removal of phenol-based organics from aqueous media

The ability of an activated carbon prepared from sawdust-based activated carbon to remove phenol and its compounds from aqueous solutions has been investigated. Activation was achieved by impregnating sawdust in phosphoric acid with concentrations ranging from 20 to 85% and heating the sawdust-acid mixture starting from 600 to 800°C. The results showed that the Brunauer–Emmett–Teller (BET) surface area exhibited by the prepared material varied significantly with experimental conditions such as impregnation time, solution pH, adsorbent dose, initial concentration, and pyrolysis temperature, and attained a value of 2,257 m2 g−1 in comparison to the as-supplied Merck commercial activated carbon (Merck-AC) attaining 1,030 m2 g−1. Characterization of the prepared materials was carried out through the determination of the BET surface area, functional groups, and surface area accessible to small and fairly large molecules (iodine and methylene blue). Batch adsorption tests were performed and the experimental data analyzed using the Langmuir, Freundlich, and Temkin models. The estimated adsorption capacities from the fitting of the Langmuir model to the equilibrium data are 200, 334, and 500 mg g−1 for phenol, parachlorophenol, and pentachlorophenol, respectively. The application of the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models to the experimental data showed that pseudo-second-order model is more representative. Thermodynamic tests revealed a spontaneous (ΔG