Statistical modeling of adsorption isotherm of potassium on aza[7]helicene-coated gold electrode attached to quartz crystal microbalance

ABSTRACT

A chemically coated piezoelectric sensor has been used for the determination in liquid phase of the adsorption isotherm of potassium. A thin film of aza[7]helicene was attached to the surface of a gold electrode of a quartz crystal microbalance using spin coating method.

Statistical physics formalism was applied to elucidate the adsorption mechanism of potassium onto coated electrode by aza[7]helicene. The simulation results showed that a monolayer adsorption occurs with the number of potassium per site about 1 and the adsorption energy is less than 30 kJ.mol⁻¹, characteristic of physical adsorption.

The statistical model was used to investigate three thermodynamic potentials such as the entropy, the free enthalpy, and the internal energy. It is found that the adsorption took place with releasing energy, such behavior confirms the exothermic character of the adsorption process.

KEYWORDS:

• Dibromoaza[7]helicene
• adsorption isotherms
• QCM
• statistical physics
• thermodynamic functions

Acknowledgments

The authors wish to acknowledge the approval and the support of this research study by the grant N° SCI-2017-1-7-F-6993 from the Deanship of the Scientific Research in Northern Border University (N.B.U.), Arar, KSA.