Fractionation of aqueous sodium salts by liquid¿liquid extraction in aqueous two phase systems

Journal article (2014)

Authors

M. Milosevic Management in the Built Environment
KJJ Staal External organisation
G Bargeman External organisation
B Schuur External organisation
A.B. de Haan ChemE/Transport Phenomena - AS
Department
Management in the Built Environment
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Published Date

2014

Language

English

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Department

Management in the Built Environment

Abstract

An important element in the work-up of brines is the separation of different ions present. Usually, energy
consuming technologies, such as multi-stage evaporation, reverse osmosis, crystallization, and nanofiltration,
are used to bring the composition of the brine to the required specification. Fractionation of salts
by liquid¿liquid extraction using thermo-responsive polymers is a novel concept. In the current study we
have evaluated the fractional extraction of sodium chloride from brines containing sodium sulfate as
well. Four different polymers (Dehypon LS 54, PPG 425, Pluronic L31 and Triton X ¿ 15) have been
used. The quaternary systems of these polymers with water, sodium chloride and sodium sulfate have
been obtained at 283.15 K and 298.15 K. From experiments at 298.15 K, it was concluded that the polymer
Dehypon LS 54 showed the most interesting combination of extracted sodium chloride yield and
selectivity of sodium chloride over sodium sulfate. The polymer losses to the feed (brine) phase were limited.
Collected extract phases were subjected to a temperature increase to 323.15 K, 333.15 K, 343.15 K,
and 353.15 K in order to study the polymer recovery by temperature induced phase splitting. It was
found that at higher temperature the miscibility gap increased strongly and limited amounts of polymer
remained in the aqueous phase.