A comparison of some commonly used adsorption isotherms in describing phosphate adsorption by hydroxy-interlayered expansible clays

摘要: Several commonly used adsorption isotherms were applied to phosphate data for 24 different complexes of hydroxyaluminum (HyA) or hydroxyaluminosilicate (HAS) ions with montmorillonite (Mt) vermiculite (Vt) clays. The evaluated regards their goodness fit utilizing criteria adopted by several earlier workers this purpose. Relative merits and limitations those discussed on statistical ground. isotherm equations found describe the levels success. two surface Langmuir equation was be best in describing suggesting existence populations sites HyA/HAS-Mt/Vt that have varying affinities ions. OH 2 groups coordinated Al atoms at broken edges HyA HAS polymers fixed external planner surfaces, and/or interlayer spaces Mt/Vt assumed predominantly involved ligand exchange reaction Region I. Ligand linking inside polymeric structure principal process II. Temkin equation, however, almost equally successful which followed Freundlich terms fit. estimated parameters fitted although numerically but positively significantly correlated each other 1% level significance these are relevant behavior as well possess wide confidence limits.