Phenol and benzenoid alcohols separation from aqueous stream using cloud point extraction: Scaling-up of the process in a mixer-settler

In the present work, the cloud point extraction (CPE) of three organic pollutants (phenol,benzyl alcohol and 1-phenylethanol) with aqueous solutions of biodegradable alkoxylated nonionic surfactants (TERGITOL 15-S-7 and SIMULSOL NW342), is investigated. First, the partial phase diagrams of the water-surfactant binary systems are established. Then, the effects of organic pollutants and sodium chloride on the cloud point (Tc) are determined. Extraction efficiency is evaluated by the following responses: percentage of solute extracted, E (%), residual concentrations of solute and surfactant in dilute phase (Xs,w, and Xt,w, respectively) and volume fraction of coacervate at equilibrium (ϕc). Three-dimensional empirical correlations are used for fitting the experimental results. The comparison between experimental and calculated values allows model parameter identification. Based on these data, CPE was implemented in a continuous mixer-settler device. The feasibility of a multi-stage crossflow process for the purification of samples containing phenol using SIMULSOL NW342 was tested. Six stages were required to reduce the pollutant concentration below the allowed level (0.3 ppm), which proves the efficiency of CPE in the treatment of wastewaters.