AdsorbentRaw chicken feathers directly obtained from a poultry-processing plant were washed with a detergent, rinsed several times with distilled water, and then left to dry at room temperature. The dry feathers were ground to pass a 20-mesh screen and then used in the sorption tests. 86 Batch adsorption experimentsSorbent was transferred into bottles containing 50 mL ofphenol solution to give a final sorbent concentration of4 mg/mL. The phenol concentrations were in the range of10–100 ppm. Distilled water was used in preparing the solutions. A temperature-controlled shaker (Kottermann, Germany) was used to agitate the mixture at the desired temperature. Experiments were carried out at 20 7C, unless otherwise stated. Samples from the solutions were taken at predetermined time intervals, for the purpose of studying the kinetics of the sorption process. Otherwise, the mixture was allowed to attain equilibrium and then the bottles were removed from the shaker for analysis. The sorbent was separated from the samples by centrifu- gation (300 g, for 10 min) and the supernatant was then analyzed for residual concentration of phenol. The method of Gales and Booth (1976), which is based on spectophotometric analysis of the developed color resulting from the reaction of phenol with 4-aminoanti- pyrine, was followed.Sorption experiments were carried out at 20 7C, 35 7C, and 45 7C to find out the effect of temperature. The effect of pH was determined by studying the adsorption of phenol over a pH range of 2–8. The pH was adjusted by addition of a diluted acid or base. Each experiment was carried out in triplicate and the average results are presented in this work. The results are expressed interms of the amount of phenol adsorbed per unit weight of sorbent, i.e., the uptake.
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