Derive the equation for solute velocity for linear isotherms \(\mathrm{q}_{\mathrm{i}}=\mathrm{K}_{{ }_{i}} \mathrm{c}_{\mathrm{i}}\) using a singleporosity model (equivalent to setting \(\varepsilon_{\mathrm{p}}=0\) ). Result obtained should be

\[ \begin{equation*} \mathrm{u}_{\mathrm{S}, \mathrm{i}}=\frac{\mathrm{v}_{\text {inter }}}{1+\frac{\left(1-\varepsilon_{\mathrm{e}}\right)}{\varepsilon_{\mathrm{e}}} ho_{\mathrm{p}} \mathrm{K}_{\mathrm{i}}^{\prime}} \tag{20-15b} \end{equation*} \]