Solvent extraction of boric acid: comparison of five different monohydric alcohols and equilibrium modeling with numerical methods


Solvent extraction of boric acid: comparison of five different monohydric alcohols and equilibrium modeling with numerical methods

Balinski, A.; Recksiek, V.; Kelly, N.

Solvent extraction is one of the common methods for the recovery of boric acid (or boron) from aqueous solutions. A wide variety of different compounds including monohydric alcohols has been tested and there is a wide recognition that they are rather ineffective compared to other extractants such as diols. Nevertheless, monohydric alcohols find application in industrial processes demonstrating their efficiency. The intention of this study is to clarify this discrepancy and to provide an overall picture of monohydric alcohols as an extractant for boric acid. Five different monohydric alcohols are the object of this study: n-octanol, 2-ethyl-1-hexanol, 2-butyl-1-octanol, 2-octanol and 3,7-dimethyl-3-octanol. A special focus is to examine the effect of the structure of carbon chain and the effect of the composition of aqueous phase on the extraction efficiency. Despite the extraction efficiency for boric acid other important properties are examined such as the viscosity of organic phase, the solubility of alcohols in aqueous phase and the co-extraction of salts used as a salting-out agent (NaCl, Na₂SO₄, MgCl₂, LiCl, LiNO₃). Finally, the relationship between the number of theoretical stages and the phase ratio at equilibrium for selected extraction systems is evaluated with MATLAB.

Keywords: boron; boric acid; solvent extraction; separation; monohydric alcohols; n-octanol; 2-ethyl-1-hexanol; 2-butyl-1-octanol; 2-octanol; 3,7-dimethyl-3-octanol

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Publ.-Id: 32126