Abstract
Chlorophenols, classified as priority water pollutants, can bioaccumulate in aquatic organisms, potentially leading to their enrichment throughout the food chain. This study investigated the utilization of a unique oil shale as a sorbent for the removal of 2,4-dichlorophenol (2,4-DCP) from aqueous solutions. The influence of various process parameters, including the contact time, sorbent/liquid ratio, temperature, and pH, on the sorption process was evaluated. The results indicated the near-complete sorption of 2,4-DCP within 24 h. Favorable sorption was observed at a sorbent/liquid ratio of 1:10, elevated temperatures, and lower pH values within the examined range. Both the Langmuir and Freundlich isotherm models were in good agreement with the equilibrium sorption data. However, the Freundlich isotherm provides a superior fit, suggesting a multilayer sorption mechanism. Kinetic studies revealed a two-stage process: intraparticle diffusion dominated the initial stage, whereas other rate-limiting mechanisms may have contributed to the second stage. The first- and second-order kinetic models suggested a combined mechanism involving physisorption and chemisorption. Physisorption appeared to be more prevalent, particularly in the second stage, whereas chemisorption governed the initial stage. These findings demonstrate the potential of the investigated oil shale as an unconventional and cost-effective sorbent, potentially serving as a substitute for activated carbon in 2,4-DCP removal.