5results about How to "High ion selectivity" patented technology

This invention provides a covalent organic framework hybrid matrix membrane, its in-situ growth method, and its application in ion separation. The method includes: dissolving cellulose derivatives, aldehyde monomers of covalent organic frameworks, and amine monomers of covalent organic frameworks in an organic solvent to obtain a first solution, a second solution, and a third solution; mixing acetic acid solution with the first, second, and third solutions to obtain a homogeneous casting solution; and drop-coating the homogeneous casting solution for in-situ growth. This invention constructs a CD@COF hybrid matrix membrane based on a cellulose derivative matrix and a low-loading covalent organic framework filler using an in-situ growth method. The prepared hybrid matrix membrane exhibits good interfacial compatibility between the matrix and the filler. The above-mentioned hybrid matrix membrane preparation process is simple, possesses good mechanical strength and high scalability, and demonstrates high ion flux and excellent ion selectivity for separating monovalent and divalent ions. It has broad application prospects in wastewater resource treatment, lithium extraction from salt lakes, and energy storage.

The invention discloses a sulfonated fluorine-containing polyimide-metal organic framework composite membrane as well as a preparation method and application thereof, and belongs to the technical field of all-vanadium redox flow battery diaphragms. The method comprises the following steps: synthesizing sulfonated fluorine-containing polyimide FSPI by using a high-temperature one-step method; preparing a metal organic framework MIL-101 (Cr) by adopting a hydrothermal method; the preparation method comprises the following steps: preparing a metal organic framework alpha-Fe2O3 / MIL-101 (Cr) by adopting a hydrothermal method; and preparing the sulfonated fluorine-containing polyimide-metal organic framework composite membrane FSPI / alpha-Fe2O3 / MIL-101 (Cr) by adopting a tape casting method. An ion transmission channel is regulated and controlled by introducing a metal organic framework alpha-Fe2O3 / MIL-101 (Cr) into sulfonated fluorine-containing polyimide. And the regulated ion transmission channel is larger than hydrated protons (lt, 0.24 nm) and smaller than hydrated vanadium ions (gt, 0.6 nm), so that the ion selectivity of the sulfonated fluorine-containing polyimide diaphragm is improved. The composite membrane prepared by the invention has high proton conductivity, good vanadium resistance and excellent ion selectivity. When the prepared composite membrane is used in the all-vanadium redox flow battery, the cycling stability of the battery is improved.

The invention provides a preparation method of a composite heterogeneous membrane, which comprises the following steps: firstly, sequentially dissolving zinc salt, 2-methylimidazole and crown ether in methanol, stirring to enable the zinc salt and the 2-methylimidazole to be subjected to coordination reaction to form a zeolite imidazole skeleton, and adsorbing the crown ether on the zeolite imidazole skeleton in situ to obtain crown ether modified zeolite imidazole skeleton particles; then, adding the graphene oxide dispersion liquid into a vacuum filtration system, and intercepting graphene oxide particles in the graphene oxide dispersion liquid by a filtration membrane in the vacuum filtration system under negative pressure to obtain a graphene oxide membrane; and adding an alcoholic solution containing the crown ether modified zeolite imidazole skeleton particles into a vacuum filtration system to intercept the crown ether modified zeolite imidazole skeleton particles on the surface of the graphene oxide membrane, and pouring phenolic resin to fix the crown ether modified zeolite imidazole skeleton particles, thereby obtaining the composite heterogeneous membrane. The invention further provides the composite heterogeneous film obtained according to the preparation method and application of the composite heterogeneous film.

The invention discloses a polymer film as well as a preparation method and application thereof. The polymer film has a spongy porous structure; the pore size of the polymer film is 0.05 to 150nm; the porosity of the polymer film is 1-200%; and the thickness of the polymer film is 10-500 [mu] m. According to the membrane prepared by the invention, the cyclohexane structure with good toughness and adjustable substituent groups is combined with the spongy pore structure obtained by the steam-induced phase separation method, so that the ionic conduction membrane with good mechanical property, good ion selectivity and good ionic conductivity is obtained. When the material is applied to a flow battery, good flow battery performance is obtained through multiple regulation and control of a cyclohexane structure, an organic solvent, a volatile solvent and a poor solvent steam atmosphere.

This invention provides a MOF-On-MOF composite ion separation membrane with a cross-linked metal ion system, its preparation method, and its application. First, an anolyl porous alumina membrane plate is immersed in a solution containing metal and a cross-linking agent, shaken, and then removed. Next, a first MOF membrane layer is grown hydrothermally. Then, metal and a cross-linking agent are deposited on the surface of the first MOF membrane layer. Finally, a second MOF membrane layer is deposited in situ on the surface. This invention, by constructing a cross-linked metal ion system, provides more stable and reliable binding sites for MOF membrane growth, enhances the binding stability between MOF membranes of different sizes, and enables the separation membrane to maintain high flux and ion selectivity even during long-term operation. Furthermore, by optimizing the addition of functional groups, the energy barrier differences between different metal ions across the membrane are strengthened, enhancing the selectivity for monovalent and polyvalent ions. The preparation method is simple and easily industrialized.