Batch Adsorption Experiments

3.6.Batch adsorption studies
Adsorption experiments were conducted as per the design developed with response surface Box-Behnken methodology. The experiments were carried out in 250-mL Erlenmeyer flasks with the working volume of 100 mL of reaction mixture. The initial pH of the solution was adjusted to the desired value by adding 0.1 M NaOH and HCl. The flasks were shaken for the specified time period in a rotary shaker. The flasks were withdrawn from the shaker after the desired time of reaction. The residual phenol concentration in the reaction mixture was analyzed by centrifuging (1800 rpm, R-24 REMI Centrifuge, Mumbai, India) the reaction mixture and then measuring the absorbance of the supernatant at the wavelength that corresponds to the maximum absorbance of the sample. Phenol concentration in

Adsorption kinetics
To investigate the adsorption processes of phenol onto sorbents the frequently used kinetic models such as the linearized form of the pseudo-first-order and pseudo-second-order models respectively, were used to determine the mechanism of the adsorption process.

3.10.Column adsorption studies
The experimental arrangement of the adsorption packed bed column is shown in figure . Continuous-flow sorption experiments are conducted in an acrylic column with an internal diameter of 3 cm and 58 cm in height. These two ends of the column are connected to filter discs and fitted with 0.45 µm cellulose filter paper; an O-ring and plug stoppers are also used as fitting items. Glass beads (1.5mm in diameter) are placed at the column base in order to provide a uniform inlet flow of the solution into the column.
A known quantity of sorbent is packed in the column to yield the desired bed height. Phenol solutions having an initial concentration of 50 mg/L are pumped upward through the column at a desired flow rate using a peristaltic pump. Samples are collected from the exit of the column at different time intervals and analyzed for phenol