2.3 Batch operation for determination of the adsorption isotherm
The batch adsorption experiment was performed in 25 ml glass Erlenmeyer flask at a fixed temperature, 23˚C. The first experiment was done by concentrating the pure TCO in n-hexane to a volume of approximately 5 ml. Then 0.192 mmol of 1,3,5 trimethoxybenzene (internal standard for1H-NMR) was added. Based on the1H-NMR result, the amount of TCO was calculated. Then, a fixed amount (0.2 g) of AgNO3/silica was added to the solution. Subsequently, the Erlenmeyer was shaken at 100 rpm in a temperature controlled shaker, for a period of 4 hours. Next, the mixture was kept in stagnant mode to let the particles sediment. From the solution a sample (0.2 ml) was taken for 1H-NMR analysis. The result is one point in the TCO adsorption isotherm. Afterwards, 3 ml of n-hexane was added to the solution and was shaken again at the same condition as previous for a period of 4 hours and consequently another sample was taken for 1H-NMR analysis. This procedure was repeated for several times and every time a certain amount of solvent was added and after shaking a sample was taken for 1H-NMR analysis.
The amount of solute (B) adsorbed per gram dry of adsorbent at equilibrium, \(q_{B}\) (gB/g), was calculated according to Eq. 2.1.
\(q_{B}=\frac{V}{W}\left(C_{B_{0}}-C_{B_{e}}\right)\) (2.1)
Where, \(C_{B_{0}}\) (g/dm3) and \(C_{B_{e}}\)(g/dm3) are respectively the initial and equilibrium concentrations of the solute (B) in the liquid phase,\(V\)(dm3) is the solution volume, and W (g) is the weight of the dry adsorbent.