Electro-membrane extraction of Li(Ⅰ)by Cyanex923/TBP/PHEN in collaboration with 2-thiophenecarbonyltrifluoroacetone
Lithium resource plays an important role in energy strategy.Membrane extraction technology is expected to solve the green sustainability problem of liquid lithium resource extraction.Binary composite extraction membranes PT-PIMs(PTC-PIM/PTT-PIM/PTP-PIM)with 2-thiophenoyltrifluoroacetone(TTA)synergistically solvated carriers[trialkylphosphine oxide mixture(Cyanex923)/tributyl phosphate(TBP)/phenanthroline(PHEN)]were prepared.The mass transfer behaviour of PT-PIMs-Li(Ⅰ)system by electric field enhancement was investigated under optimized membrane phase conditions,and the stability and Li/Na/K selective separation performance of the kerosene-modified PK-PIMs-Li(Ⅰ)system were evaluated.The results show that the membrane phase composition has a large effect on the mass transfer rate of Li(Ⅰ),the main extractant TTA plays a dominant role in Li(Ⅰ)mass transfer,and the mass transfer rate increases with the voltage.The permeability coefficient of PTC-PIM-Li(Ⅰ)system increases linearly with increasing voltage.The permeability coefficient of PTC-PIM-Li(Ⅰ)system is 33.20 μm·s-1 at 40 V.The permeation rate of Li(Ⅰ)in the PT-PIMs-Li(Ⅰ)system modified by kerosene decreased by＜21％after four cycles;When the mass concentration ratio of Li(Ⅰ)∶Na(Ⅰ)∶K(Ⅰ)in liquid phase is 20∶20∶20,the separation factors SLi(Ⅰ)/Na(Ⅰ)and SLi(Ⅰ)/K(Ⅰ)of PT-PIMs system are 8.41,4.88,3.88 and 7.99,4.64,3.81,respectively,indicating the selective separation ability of Li.The combined permeability coefficient,stability and PK-PIMs-Li(Ⅰ)systems:PCK-PIM＞PTK-PIM＞PPK-PIM.This paper provides an important idea for sustainable extraction technology of lithium resources with green energy saving.
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