Utilization of raw and activated date pits for the removal of phenol from aqueous solutions

Activated carbons prepared from date pits, an agricultural waste byproduct, have been examined for the adsorption of phenol from aqueous solutions. The activated carbons were prepared using a fluidized bed reactor in two steps; carbonization at 700 degreesC for 2 hours in N-2 atmosphere and activation at 900 degreesC in CO2 atmosphere. The kinetic data were fitted to the models of intraparticle diffusion, pseudo-second order, and Lagergren, and followed more closely the pseudo-second-order chemisorption model. The isotherm equilibrium data were well fitted by the Freundlich and Langmuir models. The maximum adsorption capacity of activated date pits per Langmuir model was 16 times higher than that of nonactivated date pits. The thermodynamic properties calculated revealed the endothermic nature of the adsorption process. The uptake of phenol increased with increasing initial phenol concentration from 10 to 200 ppm and temperature from 25 to 55 degreesC, and decreased with increasing the solution pH from 4 to 12. The uptake of phenol was not affected by the presence of NaCl salt.