Thermodynamic parameters of the activation state for phenol and three monochlorophenol (MCP) isomer-pyrite complexes, i.e., MCP isomers used were 2-chlorophenol (2-CP), 3-chlorophenol (3-CP), 4-chlorophenol (4-CP), have been derived from the temperature-dependent kinetic data. Both the initial rate and adsorption density values increased in the order phenol < 2-CP < 3-CP < 4-CP. This suggests that the presence of chlorine substituent on the aromatic ring results in enhanced CP adsorption oil pyrite. The activation energy (E-a), Gibbs free energy (Delta G(#)), entropy (Delta S-#), and enthalpy (Delta H-#) of the activation stage for MCP adsorption on pyrite were calculated by Arrhenius and Eyring models. Always Delta S-# values approximate to zero and -T Delta S-# values are positive, which indicates that the activation state of MCP adsorption process is entropy-controlled, and the observed linear dependence of Delta H-# on -T Delta S-# signals an entropy-enthalpy compensation effect of the MCP adsorption process. The Gamma(MCP) data were quantified well both by 1 - pK diffused double layer (1 - pK DLM) and Langmuir models. (c) 2005 Elsevier Inc. All rights reserved.