A functional activated carbon for efficient adsorption of phenol derived from pyrolysis of rice husk, KOH-activation and EDTA-4Na-modification

In this study, the rice husk-based activated carbon was prepared via pyrolysis of rice husk and simultaneous KOH-activation and EDTA-4Na-modification and used for phenol adsorption from water. When the rice-husk was carbonized at 500 degrees C and activated at 750 degrees C with mass ratio of carbon to KOH of 1:3, an activated carbon can be prepared, with rich micro-porosity, high specific area of 2087 m(2).g(-1) and maximum phenol adsorbance of 194.24 mg.g(-1). When the above activated carbon is prepared by simultaneous KOH-activation and EDTA-4Na-modification at 750 degrees C, N-containing functional groups were introduced to the activated carbon, which is beneficial to the adsorption of phenol. Under optimum conditions with mass ratio of carbon : KOH : EDTA-4Na = 1:3:1, the specific surface area of the resulting activated carbon decreases to 1368 m(2).g(-1), while its maximum adsorption capacity for phenol increases to 215.27 mg.g(-1). The adsorption kinetics of phenol on activated carbon agrees with the pseudo-second-order adsorption model, and the adsorption isotherm follows the Langmuir pattern.