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CN-121988182-A - Oil-soluble surfactant mediated modified nanofiltration membrane and application thereof in lithium-magnesium separation

CN121988182ACN 121988182 ACN121988182 ACN 121988182ACN-121988182-A

Abstract

The invention discloses an oil-soluble surfactant mediated modified nanofiltration membrane and application thereof in lithium-magnesium separation. The polymer substrate is soaked in ethanol solution, then is soaked in piperazine water solution, finally is soaked in trimethyl chloride n-hexane solution containing oil-soluble surfactant, and is dried, so that the oil-soluble surfactant mediated modified nanofiltration membrane is obtained. The modified nanofiltration membrane prepared by the invention can be used for separating lithium and magnesium in salt lake brine, and the separation factors of the nanofiltration membrane modified by two surfactants of dodecyl phosphate or di (2-ethylhexyl) phosphate are S Li + /Mg 2+ =78.17 and 161.65 respectively. The modified nanofiltration membrane provided by the invention has the characteristics of high separation factor, simple synthesis method operation, pollution resistance, strong stability and the like, provides an effective medium environment for the subsequent preparation of battery-level Li 2 CO 3 , and has a very strong practical application value.

Inventors

  • LOU ZHENNING
  • YANG FAN
  • CAO HONGTAO
  • CUI JUNSHUO
  • XIONG YING

Assignees

  • 辽宁大学

Dates

Publication Date
20260508
Application Date
20260325

Claims (10)

  1. 1. The preparation method of the oil-soluble surfactant mediated modified nanofiltration membrane is characterized by comprising the steps of firstly soaking a polymer substrate in an ethanol solution, then soaking the polymer substrate in a piperazine water solution, finally soaking the polymer substrate in a trimethyl chloride n-hexane solution containing the oil-soluble surfactant, and drying the polymer substrate to obtain the oil-soluble surfactant mediated modified nanofiltration membrane.
  2. 2. The oil-soluble surfactant mediated modified nanofiltration membrane of claim 1, wherein the polymer substrate is a polyacrylonitrile or polysulfone substrate.
  3. 3. The oil-soluble surfactant-mediated modified nanofiltration membrane of claim 1, wherein the oil-soluble surfactant is an organophosphate species.
  4. 4. The modified, oil-soluble, surfactant-mediated nanofiltration membrane of claim 3, wherein the organophosphate species is dodecyl phosphate or di (2-ethylhexyl) phosphate.
  5. 5. The modified nanofiltration membrane mediated by an oil-soluble surfactant according to any one of claims 1 to 4, wherein the ethanol solution has a volume percentage concentration of 30% to 50% and a soaking time of 3h to 5 h.
  6. 6. The modified nanofiltration membrane mediated by an oil-soluble surfactant according to any one of claims 1 to 4, wherein the piperazine aqueous solution has a mass percentage concentration of 0.8% -1.2% and a soaking time of 20 s-40 s.
  7. 7. The modified nanofiltration membrane mediated by an oil-soluble surfactant according to any one of claims 1 to 4, wherein the concentration of the oil-soluble surfactant in the trimethyl chloride n-hexane solution containing the oil-soluble surfactant is 0.01 g L -1 - 0.6 g L -1 , the mass percentage concentration of the tricarboxylic acid chloride in the trimethyl chloride n-hexane solution is 0.1 to 0.3%, and the soaking time in the trimethyl chloride n-hexane solution containing the oil-soluble surfactant is 20 s to 40 s.
  8. 8. Use of the oil-soluble surfactant-mediated modified nanofiltration membrane of any one of claims 1-7 for separating lithium magnesium in an aqueous solution.
  9. 9. A method for separating lithium and magnesium from an aqueous solution, characterized by using the oil-soluble surfactant-mediated modified nanofiltration membrane as claimed in any one of claims 1 to 7, wherein the aqueous solution containing lithium and magnesium is trapped at room temperature by the oil-soluble surfactant-mediated modified nanofiltration membrane.
  10. 10. The method of claim 9, wherein the pressure is controlled to be 1 bar to 5 bar, the horizontal flow rate is 10L m -2 h -1 - 50 L m -2 h -1 , and the concentration of lithium and magnesium ions in the aqueous solution is 0 ppm to 5000 ppm.

Description

Oil-soluble surfactant mediated modified nanofiltration membrane and application thereof in lithium-magnesium separation Technical Field The invention belongs to the technical field of high-crosslinking-degree nanofiltration membranes and lithium-magnesium separation, and particularly relates to an oil-soluble surfactant-mediated modified nanofiltration membrane and application thereof in lithium-magnesium separation. Background Lithium is a strategic key metal, a key material for energy conversion, and has irreplaceable importance. Lithium ion batteries are widely used in electric vehicles and portable electronic devices, resulting in a drastic increase in lithium consumption. By 2027, the market value of lithium is expected to surge to $875 billion. The global lithium resources are mainly concentrated in Australia, chilean, argentina and China, the resource distribution is unbalanced, and measures are taken in competition in all countries for guaranteeing the long-term stable supply of the lithium resources. Lithium is mainly present in solid lithium ores and salt lake brine, and 60% -80% of the global recoverable lithium reserves are contained in salt lake brine. However, salt lake brine contains a large amount of impurity ions (such as Mg 2+、Ca2+、Na+、Cl-、SO42-、CO32-), where Mg 2+ and Li + have similar hydrated ionic radii, making lithium magnesium separation a great challenge. Therefore, it is urgent to develop a novel material capable of efficiently separating Li + from salt lake brine. The current methods for extracting lithium from salt lake brine mainly comprise a precipitation method, an adsorption method, a membrane separation method, an electrodialysis method and a solvent extraction method. The membrane separation method has obvious advantages because no additional chemical reagent is used, the operation is simple, the energy consumption is low and the environment is protected. Among them, nanofiltration membranes are attracting attention because monovalent and multivalent ions can be separated without requiring a complicated operation procedure, without adding additional chemical reagents, and without chemical reactions. However, unmodified Nanofiltration (NF) membranes are not ideal. In order to realize efficient separation of lithium and magnesium, a modified nanofiltration membrane capable of effectively separating lithium and magnesium needs to be prepared. Disclosure of Invention In order to solve the technical problems, one of the purposes of the invention is to provide a modified nanofiltration membrane mediated by oil-soluble surfactant. By introducing the oil-soluble surfactant, the piperazine is promoted to diffuse to a reaction interface, so that more trimethyl chloride participates in the interfacial polymerization reaction, the side reaction of the residual acyl chloride group is reduced, the synthesized modified nanofiltration membrane has accurate pore size and stronger interception effect on magnesium ions, and lithium in salt lake brine can be effectively separated. The second object of the invention is to provide the application of the modified nanofiltration membrane based on the mediation of oil-soluble surfactant in lithium-magnesium separation. The preparation method of the oil-soluble surfactant mediated modified nanofiltration membrane comprises the steps of soaking a polymer substrate in ethanol solution, then soaking the polymer substrate in piperazine (PIP) water solution, finally soaking the polymer substrate in trimethyl chloride (TMC) n-hexane solution containing the oil-soluble surfactant, and drying the polymer substrate to obtain the oil-soluble surfactant mediated modified nanofiltration membrane. Further, the polymer substrate is a Polyacrylonitrile (PAN) or polysulfone substrate. Further, the oil-soluble surfactant is an organic phosphate substance. Still further, the organic phosphate is dodecyl phosphate (DAP) or di (2-ethylhexyl) phosphate (B (2 EH) P). Further, the volume percentage concentration of the ethanol solution is 30-50%, and the soaking time is 3 h-5 h. Further, the mass percentage concentration of the piperazine aqueous solution is 0.8% -1.2%, and the soaking time is 20 s-40 s. Further, in the trimethyl chloride-n-hexane solution containing the oil-soluble surfactant, the concentration of the oil-soluble surfactant is 0.01 g L -1 - 0.6 g L-1, the mass percentage concentration of the tricarboxylic acid chloride in the trimethyl chloride-n-hexane solution is 0.1-0.3%, and the soaking time in the trimethyl chloride-n-hexane solution containing the oil-soluble surfactant is 20 s-40 s. The invention provides application of an oil-soluble surfactant mediated modified nanofiltration membrane in separating lithium and magnesium in an aqueous solution. Further, the aqueous solution is preferably salt lake brine. A method for separating lithium and magnesium from aqueous solution adopts the oil-soluble surfactant mediated modified nanofiltration membrane