Method and apparatus for extraction and recovery of ions from solutions
AssigneeNew Jersey Institute of Technology
InventorsKamalesh K. Sirkar, Zhifa Yang, Asim Kumar Guha
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Abstract
A novel hollow fiber membrane-based synergistic extraction technique has been developed for removal and recovery of individual heavy metals from aqueous streams. This technique has a number of advantages over conventional solvent extraction, emulsion liquid membrane, and supported liquid membrane methods. It may be easily scaled up to meet the requirements for pollution control of heavy metals in industrial processes and selective separation hydrometallurgy.
Claims19
An ion transfer unit for synergistically facilitating the simultaneous extraction of at least two different ions, including first and second ions, from a feed solution, wherein said unit is capable of being used with a multi-ion extractant which is specific for at least both said first and second ions and with at least first and second auxiliary extractants, wherein the first auxiliary extractant is specific for at least the first ion and the second auxiliary extractant is specific for at least the second ion, said ion transfer unit comprising:
- a fluid-tight housing having an interior shell surface defining an extractant chamber;
- a feed solution member including at least one hollow fiber membrane disposed within said extractant chamber and connected to said housing, said hollow fiber membrane having an outer surface for contacting the multi-ion extractant and an inner surface for contacting the feed solution and defining a feed solution chamber, wherein said membrane is wettable by one of the feed solution and the multi-ion extractant thereby providing for formation of a stable interface in the pores of said membrane between the feed solution and the multi-ion extractant;
- a pressure difference control means for maintaining a difference between a liquid pressure of the multi-ion extractant in said extractant chamber and a liquid pressure of the feed solution in said feed solution chamber within a predetermined pressure range so that said interface between the multi-ion extractant and the feed solution is substantially immobilized in the pores of said membrane of said feed solution member, thereby effectively preventing dispersion of the multi-ion extractant and the feed solution on opposing sides of said membrane;
- at least two auxiliary extractant members, each auxiliary extractant member including at least one hollow fiber membrane disposed within said extractant chamber and connected to said housing, each said hollow fiber membrane having an outer surface for contacting the multi-ion extractant and an inner surface for contacting one of the auxiliary extractants and defining a respective auxiliary extractant chamber, wherein each said membrane is wettable by one of the multi-ion extractant and the respective auxiliary extractant disposed within its respective auxiliary extractant chamber in order to provide a stable interface in the pores of said membrane between the multi-ion extractant and the respective auxiliary extractant;
- at least two auxiliary pressure difference control means, wherein each auxiliary pressure difference control means maintains a respective difference between the liquid pressure of the multi-ion extractant in said extractant chamber and a liquid pressure of the respective auxiliary extractant in its corresponding auxiliary extractant chamber substantially within a respective predetermined pressure range so that interfaces between the multi-ion extractant and the respective auxiliary extractant are substantially immobilized in the pores of said membrane of its respective auxiliary extractant member, to effectively prevent dispersion of the multi-ion extractant and respective auxiliary extractants on opposing sides of respective membranes;
- wherein said unit is capable of simultaneously allowing ion transfer between the feed solution and the multi-ion extractant through said feed solution member, and between the multi-ion extractant and the auxiliary extractants through respective auxiliary extractant members;
- whereby said ion transfer unit is capable of synergistically facilitating the extraction of at least said first and second ions from said feed solution chamber into said extractant chamber by allowing simultaneous selective removal of the ions from said extractant chamber into respective auxiliary extractant chambers by respective auxiliary extractants.
The ion transfer unit according to clam 1 wherein said extractant chamber further comprises an extractant solvent specific for anions and cations.
A method for synergistically and selectively removing at least two ionic solutes from a feed solution using an ion transfer system, a multi-ion extractant specific for the at least two ions and at least two ion-specific auxiliary extractants, wherein one of the auxiliary extractants is specific for one of the at least two ions and wherein another of the auxiliary extractants is specific for another of the at least two ions, the system including:
- a housing defining a shell-like extractant chamber for accommodating the extractant solvent;
- a feed solution HFM member disposed within the extractant chamber and comprised of a porous membrane which defines a feed solution chamber therein, the porous membrane being wettable by one of the feed solution and the multi-ion extractant;
- and at least two auxiliary extractant HFM members disposed within the extractant chamber, each comprised of a porous membrane which defines respective auxiliary extractant chambers, each porous membrane being wettable by the multi-ion extractant or by a respective auxiliary extractant;
- the method comprising the steps of:
- introducing the multi-ion extractant into the extractant chamber and into simultaneous contact with the feed solution member and the auxiliary extractant members;
- introducing the feed solution into the feed solution chamber;
- introducing the auxiliary extractants into respective auxiliary extractant members;
- maintaining a stable interface between the multi-ion extractant and the feed solution within the porous membrane of the feed solution member, thereby preventing dispersion of the multi-ion extractant and the feed solution on opposing sides of the membrane;
- and
- maintaining a stable interface between the multi-ion extractant and the respective auxiliary extractants within the porous membrane of each respective auxiliary extractant member, thereby preventing dispersion of the multi-ion extractant and the respective auxiliary extractants on opposing sides of each respective membrane;
- whereby the at least two ions are simultaneously transferred from the feed solution to the multi-ion extractant while the at least two ions are simultaneously transferred from the multi-ion extractant to respective auxiliary extractants.
A method for selectively and synergistically removing at least two different ionic solutes from a feed solution with a multi-ion extractant, which is specific for both the at least two different ionic solutes, and at least two auxiliary extractants, wherein at least one of the auxiliary extractants is specific for one of the at least two ions and wherein at least one other of the auxiliary extractants is specific for another of the at least two ions, the method comprising:
- providing a first stable interface between the feed solution and the multi-ion extractant at a first porous membrane;
- providing a second stable interface between the multi-ion extractant and one of the auxiliary extractants at a second porous membrane;
- and
- providing a third stable interface between the multi-ion extractant and the other of the auxiliary extractants at a third porous membrane, wherein the multi-ion extractant simultaneously contacts the first, second and third stable interfaces;
- whereby the at least two ions are simultaneously transferred from the feed solution to the multi-ion extractant, while each of the at least two ions are also simultaneously transferred from the multi-ion extractant to respective auxiliary extractants.
Dependencies are inferred from the claim text.