Optimization of preparation conditions for activated carbons from date stones using response surface methodology

The optimal conditions for preparation of activated carbons from date stones by ferric chloride activation (FAC) and commonly used zinc chloride activation (ZAC) were investigated. The influence of activation time, activation temperature, and impregnation ratio on the yield and phenol (Ph) uptake of such carbons were studied. Based on Box-Wilson central composite design, two second order polynomial models were developed to correlate the process variables to the two responses. From the analysis of variance the significant variables on each response were identified. For FAC, an optimum condition of 76 min activation time, 707 degrees C activation temperature, and 1.6 impregnation ratio gave 97.96 mg/g Ph uptake and 47.24% yield, while for ZAC, 86.11 mg/g Ph uptake and 39.16% yield were obtained at 30 min activation time, 717 degrees C activation temperature, and 0.5 impregnation ratio. The Langmuir isotherm was used to correlate equilibrium data of Ph adsorption, showing maximum Ph uptake of 170.97 and 161.54 mg/g for FAC and ZAC, respectively. Also, the characteristics of both carbons were determined and found to have surface areas of 780.06 and 1045.61 m(2)/g, respectively. (C) 2012 Elsevier B.V. All rights reserved.