oo remained constant. When both the water level and the pH were constant for a ten minute period the process was considered to be at steady state. Samples of the extract and raffinate were taken to measure the benzoic acid concentration. For the aqueous phase the pH was taken and Figure 1 was used to determine the acid concentration. In the organic phase a measured amount of the raffinate was mixed with a measured amount of tap water and brought to equilibrium by mixing as was done for the feed kerosene. The aqueous phase was then measured for pH and the corresponding concentration. This concentration was used along with Figure 2 to determine the equilibrium concentration in the kerosene and then to determine the initial concentration in the raffinate. The concentrations of the extract and the raffinate could then be compared to the concentration in the feed kerosene to complete a mass balance. This process was repeated so that two steady state conditions were reached. Having collected all of the data necessary to measure the mass transferred, we began to finish the experiment by emptying the column and labeling the contents of the storage tanks. Following the procedure in Perrys Handbook (6thedition) we drew operating lines next to the equilibrium curve using the data collected. These lines could then be used to determine the number of theoretical stages and the HETS. The following graph shows the operating lines drawn from experimental data and the equilibrium curve taken from Allerton (1943): Figure. 3As can be seen from Figure 3 it was difficult to determine the number of theoretical stages from the operating lines and equilibrium curve using a graphical method. Because of this difficulty we also used one of the Kremser equations from Perrys Handbook to determine the number of theoretical stages. Equation. 1 Where (m) is the slope of the equilibrium line, (e) is the extraction factor, (Xf) is the benzoic acid concentr...
