Aqueous biphasic separation of thallium from aqueous solution using alcohols and salts

摘要

The behavior of aqueous biphasic extraction of thallium (Tl) using different alcohols and salts was investigated. The extraction of Tl(III) was driven by the Tl-chlorocomplex (TlCl4-) that formed with Tl(III) and chloride. The addition of appropriate amount of salt and alcohols helped form the organic-water stratification, in which Tl and alcohols were enriched in the upper phase while the most water and salt were separated in the bottom phase. Both the two-phase systems of alcohols (propanol and butanol)-NaCl and alcohols-(NH4)(2)SO4 were effective in Tl(III) extraction but poor for Tl(I) separation. The ethanol-(NH4)(2)SO4 system allowed good separability of Tl(III) from Tl(I) while ethanol-NaCl one gave no stratification. In n-propanal-NaCl extraction system, the Tl(III) extraction was stable at the contact time ranging from 0.5 to 10 min. Reaction temperature and acidity had little effect on the extraction performance. Tl(I) oxidized by ozone, bromine water, hydrogen peroxide, and hypochlorite yielded high fractional extraction of Tl(III). The alcohols-salts two-phase system can not only be a potential means to the analysis of Tl speciation but also an alternative technique to the extraction of Tl in water and wastewater.