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°C in the presence of nitrogen. Physical activation was carried out by treating the resultant pyrolyzed oil shale with CO₂ at 830°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.