Desorption kinetics of polycyclic aromatic hydrocarbons from kaolinite co-contaminated by heavy metals at various organic matter contents
Document Type : Original Research
Authors
1
University Canada West
2
Southern Cross University
10.48311/jaert.2026.114491.0
Abstract
This study examines the simultaneous desorption kinetics of PAHs (acenaphthene, fluorene, and fluoranthene) and heavy metals (Ni, Pb, and Zn) from co-contaminated kaolinite containing three levels of humic acid. Desorption was carried out using enhancing agents, including non-ionic surfactants, a chelating agent, and citric acid. The data were fitted with four kinetics models: pseudo-second-order equation, empirical power function, Elovich, and parabolic diffusion. Results showed that combinations of Triton X-100 (7.5% w/w) + EDTA (0.01M) and Tween 80 (7.5% w/w) + EDTA (0.01M) resulted in the highest removal efficiencies of ∑PAHs, 91.3 and 91.4%, respectively. PAHs desorbed mostly within 24 h, and maximum desorption reached between 48 and 72 h. The organic matter content in kaolinite was observed to reduce the kinetic rate of contaminant desorption. A pseudo-second-order equation fitted the kinetic data better than the other three models for all contaminants tested at all three humic acid kaolinite content levels.
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