Use of activated oil shale for the removal of 2,4-dichlorophenol from aqueous solutions

Sorption of the phenolic compound 2,4-dichlorophenol (2,4-DCP) by pyrolyzed and different forms of treated residue of Jordanian oil shale was examined. Pyrolyzed oil shale was prepared using a fluidized bed reactor at 520 degrees C in the presence of nitrogen. Physical activation was carried out by treating the resultant pyrolyzed oil shale with CO2 at 830 degrees C, while chemical activation of oil shale was carried out using KOH and ZnCl2 as impregnating agents. Uptake of 2,4-DCP onto the different types of sorbents increased in the order ZnCl2-OS > Pyr-OS > CO2-OS, with minimal uptake when KOH-OS was used. The process was found to be exothermic in nature. An increase in the initial pH of the solution negatively influenced the sorption of 2,4-DCP. The isotherm experimental data fitted reasonably to the Langmuir, Freundlich and Redlich-Paterson models. According to kinetics studies, the rate of 2,4-DCP sorption onto ZnCl2-OS was faster than that by Pyr-OS. Three kinetics models, namely the Morris-Weber model, Lagergren model, and pseudo-second-order model (PSOM), were applied to represent the experimental results for both pyrolyzed and ZnCl2-oil shale sorbents.