Thermodynamics of monochlorophenol isomers and pyrite interfacial interactions in the activation state

• Published in: Journal of colloid and interface science 2006-05, Vol.297 (1), p.31-37
• Main Authors: Weerasooriya, R., Makehelwala, M., Miedaner, M.M., Tobschall, H.J.
• Format: Article
• Language: English
• Subjects: Activation state; Chemistry; Electrical double layer; Exact sciences and technology; General and physical chemistry; Langmuir model; Monochlorophenol isomers; Phenol; Pyrite
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2005.10.009

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 on pyrite. The activation energy ( E a ) , Gibbs free energy ( Δ G # ) , entropy ( Δ S # ) , and enthalpy ( Δ H # ) of the activation stage for MCP adsorption on pyrite were calculated by Arrhenius and Eyring models. Always Δ S # values approximate to zero and − T Δ S # values are positive, which indicates that the activation state of MCP adsorption process is entropy-controlled, and the observed linear dependence of Δ H # on − T Δ S # signals an entropy–enthalpy compensation effect of the MCP adsorption process. The Γ MCP data were quantified well both by 1 − p K diffused double layer ( 1 − p K DLM) and Langmuir models.