Aqueous Surfactant Two‐Phase Systems for the Continuous Countercurrent Cloud Point Extraction

Abstract

Aqueous nonionic surfactant solutions split into two phases if the temperature is increased beyond a certain temperature, the so‐called cloud point temperature. Presently many different types of nonionic surfactants are produced commercially, out of these numerous have been considered as potential solvent for the cloud point extraction. In this work the crucial thermophysical properties of nonionic surfactants are investigated to determine the potential of surfactant systems for extraction processes. Phase equilibria of the binary system Triton X‐114/water and the ternary system Triton X‐114/water/phenol were measured. Based on these data the cloud point extraction was implemented in a continuous stirred extraction column. It was found, that increasing temperature within the column reduces the loss of surfactant and leads to an increasing enrichment factor. This work demonstrates that surfactant/water systems represent a suitable alternative to conventional solvents and can effectively be processed in continuous extraction columns.

Determination of Acoustical Parameters of Aqueous Solution of Kolliphors Binary Mixtures Using Density, Speed of Sound, Viscosity, and Surface Tension Measurements

“…Micellar systems are widely applied in chemical, biochemical, and pharmaceutical areas as solubilizing agents and also constitute a basis for drug delivery or solvent systems in separation processes. Moreover, some aqueous solutions with nonionic surfactants can be applied in extraction processes being of significant importance in biotechnological product purification (Ingram et al, ; Lam et al, ). In pharmacy, nonionic Kolliphors (known before as Cremophors) find application in lipid‐based delivery aimed at improving poorly water‐soluble drugs (Berthelsen et al, ; Gelderblom et al, ).…”

Continuous Countercurrent Extractive Biocatalysis in Aqueous Surfactant Two‐Phase Systems

“…At a temperature of 37 °C, the Tergitol NP‐7 weight fraction in the micellar phase is around 23.5 wt %, which is a sufficient concentration to accumulate PAA in the micellar phase in extraction processes, as will be shown below. Generally, the surfactant content in the aqueous phase is in the range of the critical micellar concentration ( < 0.01 wt %, cms Tergitol NP‐7 = 0.003 wt % (manufacturer information)) whereas the phase composition of the micellar phase strongly depends on the temperature. However, the continuous extraction was performed in presence of a phosphate buffer, which influences the miscibility gap.…”

“…In the last years the CPE was applied for various processes such as the separation and accumulation of proteins and biomolecules, as well as for wastewater treatment , , . The research group around Scamehorn , and our group , extended the application of micellar systems to continuous countercurrent extraction processes. However, not all surfactants meet the necessary requirements for the cloud point extraction.…”

“…The surfactant concentration in the aqueous phase is usually in the range of the critical micellar concentration (cmc). In the micellar phase the surfactant content is a function of the temperature [14]. Homogenous surfactant solutions form micellar aggregates if the surfactant concentration is above the cmc.…”

“…Thus, it can be assumed that in the surfactant-rich phase micelle-like structures are present. Hence, any species that solubilizes in the micelles can be simply extracted by rising the temperature above the CPT [14,17]. This technique is referred to as cloud point extraction (CPE).…”