Since the extraction temperature of acetic acid extraction prior to terephthalic acid production are desired at T = 313.2 K and atmospheric pressure. The temperature has been carried out since the aqueous solution that fed to extractor column is originally coming from the top product of distillation column in the upstream process, also keeping the temperature at 313.2 K to avoid the crystallization of acetic acid during the process. Therefore, the experimental liquid-liquid equilibrium data for the quaternary system involving methyl acetate + p-xylene + water + acetic acid at a desired temperature and pressure were performed, as shown in Table 2. The data given in Table 2 were shown as mass fraction. The compositions of the feed mixtures for …show more content…
To indicate the separation effect for different ratio of p-xylene to methyl acetate more clearly, Fig. 4 shows the dependence of selectivity on the water/acetic acid mass ratio in the initial mixture for various different ratios of p-xylene to methyl acetate in the initial mixture. These results reveal the general capability of mixed solvent to extract acetic acid from the aqueous phase at different feed composition. As mentioned earlier, methyl acetate has been put up in this industrial operation, since it was available as the byproduct of terephthalic acid production. As can be seen in Fig.4, a higher ratio of p-xylene to methyl acetate can produce higher selectivity of acetic acid against water. It showed the positive influence of the high amounts of p-xylene on the selectivity. This is coherent with the idea that adding p-xylene into methyl acetate as a mixed solvent could lead to enhance the values of capacity of extraction and selectivity of acetic acid against water. This result showed p-xylene is powerful enough to be considered as the feasible solvent when mixed with methyl acetate. Likewise, the use of p-xylene …show more content…
Thus, Fig. 3 also presents the comparison of the curves calculated from the NRTL model with the experimental results for the quaternary system. In addition, the low RMSD values for NRTL and UNIQUAC confirm the ability of these models provide the LLE data in this work. Furthermore, successful prediction using the obtained binary interaction parameters by the simultaneous correlations (NRTL and UNIQUAC) of all the experimental LLE data of this quaternary system contributes to create a reliable conceptual design and process simulation and optimization of acetic acid extraction from