## 3 Results and Discussion
### Thermodynamic Parameter of Adsorption  
The thermodynamic parameter of adsorption at the air/water interface for tyramine is different as compared to taurine because of the presence of the C\({}_{6}\)H\({}_{5}\)CH\({}_{2}\) -group. The tyramine aromatic moiety and a highly hydrophilic head group of glucose molecules induce a hydrophobically rich environment at the air-liquid interface, which dominates over the effect of \(\pi\)-conjugation. Tyramine was found to behave as a non-ionic surfactant and its phenyl ring was directed into the micellar core, where it is held by hydrophobic interaction. Therefore, it is concluded that the free energy of tyramine aggregation, \(\Delta G^{o}{}_{ag}\), is associated with the change from a monomeric to an aggregated state, in the case of a non-ionic surfactant, as calculated by Equation (8) of Section 2.3. Moreover, the Equations (9) and (10) of Section 2.3 were used to calculate the free energy of adsorption, \(\Delta G^{o}_{ad}\), and standard entropy of adsorption, \(\Delta S^{o}_{ad}\), respectively. \(\Delta G^{o}_{ad}\) has been calculated from the values of surface pressure, surface area per molecule, and the Gibbs free energy of aggregation. Meanwhile, the standard entropy of adsorption, \(\Delta S^{o}_{ad}\), was estimated from the slope of the free energy of adsorption \(\Delta G^{o}_{ad}\) versus temperature T, as depicted in Figure 7, and the said values are tabulated in Table 6. In addition, the enthalpy of adsorption, \(\Delta H^{o}_{ad}\), was calculated by a thermodynamic relation, as per Equations (10) (Section 2.3). The \(\Delta G^{o}{}_{ag}\) and \(\Delta G^{o}_{ad}\) values are listed in Table 6, which shows negative values at all temperatures, indicating that the micellization and adsorption process is spontaneous in nature. The values of \(\Delta G^{o}_{ad}\) are more negative than \(\Delta G^{o}{}_{ag}\) because less energy is required for adsorption at a higher temperature; hence, the dehydration of the hydrophilic group occurs [48]. On the other hand, the \(\Delta H^{o}_{ad}\) values, as tabulated in Table 6, are positive, which suggests that the process of adsorption at the air/water interface is endothermic in nature. The numerical positive \(\Delta S^{o}_{ad}\) values (illustrated in Table 6) indicate the freedom of monomers at the interface; thus, the tyramine-glucose interaction is favored only by the entropy change. The \(\Delta H^{o}_{ad}\) and \(\Delta S^{o}_{ad}\) compensation effect is reported in the literature for many physiochemical processes. An increase in temperature reveals that the numerical values of \(\Delta G^{o}_{ad}\) are increased slightly, which governs that the adsorption of the glucose molecule at surface formation is mainly favored by the entropy-driven and enthalpy effect.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Glucose + aq. Taurine** \\ \hline
**m (mol\(\cdot\)kg\({}^{-1}\))** & \(\Delta S\)/(kJ\(\cdot\)mol\({}^{-1}\) K\({}^{-1}\)) & \(\mathbf{R^{2}}\) \\ \hline
0 & 0.215 \(\pm\) 0.0046 & 0.99826 \\
0.01 & 0.217 \(\pm\) 0.0050 & 0.99862 \\
0.02 & 0.202 \(\pm\) 0.0044 & 0.99928 \\
0.03 & 0.183 \(\pm\) 0.0079 & 0.99947 \\
0.04 & 0.164 \(\pm\) 0.0045 & 0.99715 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Entropies, \(\Delta S\)/(kJ\(\cdot\)mol\({}^{-1}\) K\({}^{-1}\)), and linear regression coefficients, R\({}^{2}\) (surface tension vs. temperature), of surface formation of aqueous taurine amino acid with D-glucose solution at different temperatures.