Simultaneous Desorption and Desorption Kinetics of Phenanthrene, Anthracene, and Heavy Metals from Kaolinite with Different Organic Matter Content

ABSTRACT

Soils contaminated simultaneously with polycyclic aromatic hydrocarbons (PAHs) and heavy metals pose major threat to human health and environment by getting released from soil into water environment. The purpose of this study was to evaluate simultaneous desorption and desorption kinetics of PAHs (phenanthrene and anthracene) and heavy metals (lead, nickel, and zinc) from artificially contaminated kaolinite soils with different organic matter content. Batch desorption tests were conducted using single and combined enhancing agents containing Triton X-100 and Tween 80 as non-ionic surfactants, Ethylenediaminetetraacetic acid (EDTA) as a chelating agent, and citric acid as an organic acid. The solution with the highest removal efficiency was the combined solution of Triton X-100 (10% w/w) + EDTA (0.01 M). Removal levels around 92, 46, 92, 95, and 96% were obtained for phenanthrene, anthracene, lead, nickel, and zinc, respectively, by using this combination. Batch desorption kinetics experiments were performed using the mentioned combination. During the first 24 h, desorption kinetics were rapid, followed by a plateau until the end. The data obtained from desorption kinetics experiments were fitted with four kinetics models: pseudo-second-order equation, empirical power function, elovich, and parabolic diffusion. The correlation coefficient of the pseudo-second-order equation was higher than that of other functions. Moreover, batch experiments have showed inverse correlations between removal efficiency and organic matter content of soil.

KEYWORDS:

• Desorption
• desorption kinetics
• PAHs
• heavy metals
• kaolinite
• organic matter

Additional information

Funding

This research was partially funded by Iran University of Science and Technology.