Investigation of Adsorption behaviour of Acetone Vapour towards a Surface Plasmon Resonance Sensing Layer using Adsorption Isotherm Models

Abstract

Abstract Surface plasmon resonance (SPR) sensors are widely explored due their ultra-sensitivity to even a minute alteration of refractive index. Knowledge of adsorption processes could be exploited to explain the performance and interaction mechanism of an SPR sensor. Here in, we report the fitting of the experimental SPR sensing data during the detection of low concentrations of acetone vapour (0.5-5 ppm) using the linearized and non-linearized format of the Langmuir and the Freundlich isotherm models. The sensing layer is made from a ternary composite material of doped polyaniline, reduced graphene oxide and chitosan. The objective is to find the best model, understand the interaction mechanism and investigate the performance of the sensing layer. Correlation factors and error values were used to determine the best fit. The results showed that the Freundlich model could fit the data better than the two formats of the Langmuir model. Also, the interaction mechanism was predicted to be the physical one due to the heterogeneity parameter value, n<1. In addition, the selectivity of the sensing toward acetone compared to water, methanol, ethanol and propanol vapours was explained in terms of proximity of solubility parameters. Moreover, the ternary based sensor was found to be reversible and stable.