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In this work, to evaluate the new circle microchannel device for the removal of Cu2+ from water, various parameters on the mass transfer effect and extraction efficiency were investigated by employing bis(2-ethylhexyl) phosphate (D2EHPA) as an extractant and kerosene as a solvent. The mechanism of Cu2+ extraction from water by D2EHPA(R2H2) is as follows: Cu2+ + 2.1(R2H2)(o) ⇔ (CuR2.2.2RH)(o) + 2H(o)+. The contact time and microchannel diameter were found to have great effect on the volumetric mass transfer coefficient (KLa). However, the temperature, the initial pH of water solution, and the D2EHPA volume fraction of the extraction system nearly had no effect on the KLa. The results of this study revealed that the new circle microchannel may be an effective device for liquid-liquid microextraction as the extraction efficiency for Cu2+ was more than 98% by three stage extraction under optimized conditions. [ABSTRACT FROM AUTHOR]

The predispersed solvent extraction (PDSE) is a new method for separating solutes from aqueous solution, and for its high extraction ratio, the PDSE presents huge potential for the extraction from dilute solution. In the present paper, colloidal liquid aphrons are successfully generated using kerosene as a solvent, di(2-ethylhexyl)phosphoric acid (D2EHPA) as an extractant, sodium dodecyl benzene sulfate (SDBS) as surfactant in the aqueous phase, and polyoxyethylene sorbitol anhydride monolaurate (Tween-20) in oil phase. The extraction of Mg2+from ammonium dihydrogen phosphate solution is studied by using colloidal liquid aphrons (CLA) and colloidal gas aphrons (CGA) in a semibatch extraction column. To study the extraction ratio and advantages of the PDSE process in the removal of Mg2+, various parameters, initial Mg2+concentration, D2EHPA volume fraction, reaction temperature, phase volume ratio, mass fractions of dodecyl trimethylammonium bromide (HTAB), mass fractions of SDBS, mass fractions of Tween-20, and initial pH of NH4H2PO4solution, are studied and optimized. The results show that Mg2+in NH4H2PO4solution can be effectively removed by the PDSE process. An extraction ratio of more than 86.3% is attained at the optimized parameters, and superior-grade NH4H2PO4(MAP) can be obtained by two levels of extraction. [ABSTRACT FROM AUTHOR]