Liquid-liquid extraction of oleochemical mixtures using water at elevated temperatures and pressures.

摘要

Existing methods for separating the components of tall oil and soybean oil deodorizer distillate result in a significant loss of oleochemicals due to side reactions, or otherwise require the use of hazardous organic solvents. This work describes a new method for separating mixtures of oleochemicals. In this method, water at elevated temperatures and pressures is used to separate fatty and rosin acids from neutrals such as sterols and tocopherols.; A continuous-flow apparatus was used to investigate the phase behavior of several oleochemical-water systems. First, the phase behavior of the binary systems oleic acidwater and {dollar}alpha{dollar}-tocopherol-water was measured at temperatures from 522 to 630 K and pressures between 45 and 200 bar. Next, samples of crude tall oil and soybean oil deodorizer distillate were extracted with water at temperatures from 571 to 585 K and pressures from 110 to 121 bar. The results of these experiments clearly showed that water is selective for fatty and rosin acids over sterols and tocopherols. Subsequently, water-extracted tall oil and unextracted crude tall oil were both purified by vacuum distillation. Results showed a higher acid yield and a higher acid purity for the water-extracted tall oil.; Finally, liquid-liquid equilibrium data for the ternary system oleic acid-{dollar}beta{dollar}-sitosterol-water were measured at temperatures from 575 to 586 K and pressures from 102 to 119 bar. The experimental data were modeled with the NRTL and UNIQUAC activity coefficient equations.; As part of this work, a new method for the analysis of mixtures of fatty and rosin acids, sterols, and tocopherols in aqueous solutions was developed. This method is much simpler than conventional analytical methods and considerably reduced the time required for sample analysis.; As a result of this study, a process for the separation of the acid fraction from the neutral fraction in oleochemical mixtures is proposed. In this process, liquid water at elevated temperatures extracts the acid fraction and a neutrals-rich raffinate is obtained. The best potential application for this process is in the extraction of hardwoods-derived tall oil, because its high neutrals content results in the highest losses of oleochemicals.