34 results about "Ionic selectivity" patented technology

The invention belongs to the technical field of membranes, and particularly relates to a composite membrane with polyfunctional group organic mesoporous nanoparticles as a middle layer and a preparation method of the composite membrane. The composite membrane is of a three-layer structure and comprises a porous supporting layer, a middle layer and a selective separation surface layer, the middle layer is polyfunctional group organic mesoporous nanoparticles with good water dispersibility and excellent stability, and the selective separation surface layer is polyamide; the preparation method comprises the following steps: loading organic mesoporous nanoparticles on the surface of the porous support layer to form the middle layer; and polymerizing on the surface interface of the middle layer to form a selective separation surface layer. The middle layer contains polyfunctional groups, can interact with a water-phase polyamine monomer and controls the diffusion of the monomer in an interfacial polymerization process, so that the structure of the selective polymer separation layer is regulated and controlled, and the surface appearance and thickness of the separation layer are optimized; due to the mesopore hydrophilic property of the middle layer, a rapid water transmission channel can be constructed, and the membrane flux is effectively improved. The composite membrane provided by the invention has excellent water flux, salt rejection rate and monovalent and divalent anion selectivity.

The invention discloses a preparation method and application of a monovalent cation selective membrane for efficient lithium-magnesium separation, and belongs to the technical field of preparation of cation selective membranes. The monovalent cation selective membrane is composed of a polyamide nanofiltration base membrane and a polyethyleneimine positive electricity layer, and the preparation method comprises the following steps: taking piperazine anhydrous as a water phase concentration and trimesoyl chloride as an oil phase monomer, reacting on a polyethersulfone ultrafiltration base membrane, and preparing the polyamide nanofiltration base membrane by utilizing an interfacial polymerization method; and anchoring on the surface of the polyamide nanofiltration base membrane by utilizing cross-linking of gallic acid and PEI with the molecular weight of about 70000 through a multi-layer deposition method to obtain the Gallic-PEI / polyamide composite membrane with the positively charged surface. The membrane can realize lithium-magnesium separation through pore size screening and electrostatic repulsion effect, and has high lithium-magnesium selectivity while maintaining large lithium ion flux in the application process of an electrodialysis system, so that the lithium-magnesium separation effect of salt lake brine is improved.

The invention relates to the technical field of organic waste resource utilization, and discloses a method for co-production of lactic acid and crude grease by using perishable garbage, and the method comprises the following steps: step a, preparing the perishable garbage into slurry; b, feeding the slurry into an electrochemical reactor for electrochemical treatment; c, carrying out acidification treatment on the generated fatty acid salt to recover crude oil; and step d, carrying out lactic acid fermentation on the residual liquid rich in the small molecular sugar after the crude oil is recovered to obtain the lactic acid. The anode region and the cathode region which are separated by the ion selective diaphragm are arranged in the electrochemical reactor, and acid and alkali are respectively generated in situ in the two regions by utilizing water electrolysis and are directly used for hydrolysis of polysaccharide and saponification of grease, so that chemical reagents such as sulfuric acid and caustic soda do not need to be additionally added; the introduction of extra impurity ions such as sulfate radicals and sodium ions into the system is avoided, the load of subsequent product separation and wastewater treatment is reduced, and the process flow is simplified.

A method for coupling energy storage and hydrogen production for lithium extraction from brine, as well as a device and application thereof, the method comprising the following steps: providing an electrolytic device separated by an inorganic solid lithium ion sieve membrane into an anode chamber and a cathode chamber, arranging an energy storage electrode in the anode chamber and a hydrogen evolution electrode in the cathode chamber, introducing lithium-containing brine into the anode chamber and a recovery solution into the cathode chamber, and connecting a power supply to make lithium ions migrate from the anode chamber to the cathode chamber through the lithium ion sieve membrane, while the anode undergoes an oxidation reaction of energy storage material to convert electrical energy into chemical energy storage, and the cathode undergoes a hydrogen evolution reaction to generate hydrogen. The present application controls the anode electrochemical reaction path to replace the traditional oxygen evolution and chlorine evolution reaction with energy storage reaction, while achieving selective extraction of lithium ions, storing electrical energy in the form of chemical energy in the energy storage electrode, and simultaneously producing hydrogen in the cathode, effectively avoiding the generation of toxic chlorine gas, reducing the energy consumption of lithium extraction, and realizing the multiple coupling of lithium extraction, energy storage and hydrogen production processes.

The present disclosure relates to a method for making a carbon aerogel electrode material. The method involves initially making a wet organic sol-gel form. The sol-gel form is carbonized at a temperature of from about 900° C. to about 1000° C., for from about 2 hours to about 4 hours. The carbonized sol-gel is then activated under carbon dioxide flow, for from about 0.5 hour to about 1.5 hours, at from about 900° C. to about 1000° C.

The application relates to the technical field of adsorbents, and discloses a cadmium ion selective adsorbent and a preparation method thereof, which is prepared from the following raw materials in parts by weight: 2-3 parts of aminoundecanoic acid, 2-3 parts of citric acid, 0.45-0.6 parts of NaOH, 4-6 parts of cellulose, 4-6 parts of thiocyanogen, 4-6 parts of nano silicon dioxide, 450-650 parts of MES buffer solution, 500 parts of PBS buffer solution, 8-12 parts of a coupling agent, 8-12 parts of a crosslinking agent, 0.4-0.6 parts of metallothionein and 20-30 parts of water. The application bonds the metallothionein and the carbon dot surface carboxyl through an amide reaction, and combines the modified cellulose through a large number of hydrogen bonds, so that the combination capacity of the two is greatly enhanced, and the stability of the adsorbent is improved. The prepared adsorbent has excellent selective adsorption for cadmium, excellent tolerance for some common coexisting interfering ions in water bodies, and excellent industrial application prospect.

The invention relates to the technical field of adsorbents, and discloses a preparation method of a cadmium ion selective adsorbent. The invention relates to a water-based metal corrosion inhibitor which comprises the following components in parts by weight: 2-3 parts of amino undecanoic acid, 2-3 parts of citric acid, 0.45-0.6 part of NaOH, 4-6 parts of cellulose, 4-6 parts of thiourea, 4-6 parts of nano silicon dioxide, 450-650 parts of an MES buffer solution, 500 parts of a PBS buffer solution, 8-12 parts of a coupling agent, 8-12 parts of a cross-linking agent, 0.4-0.6 part of metallothionein and 20-30 parts of water. Metallothionein is bonded with carboxyl on the surfaces of the carbon dots through an amide reaction and is bonded with modified cellulose through a large number of hydrogen bonds, the bonding capacity of the metallothionein and the modified cellulose is greatly enhanced, and the stability of the adsorbent is improved. The adsorbent prepared by the invention has excellent selective adsorption to cadmium, has excellent tolerance to some common coexisting interfering ions in a water body, and has excellent industrial application prospects.

The invention discloses a PVDF production fluorine-containing wastewater resourceful treatment system and method based on ion exchange resin, and belongs to the technical field of industrial wastewater treatment. The system comprises a pretreatment unit, a deep purification unit, a regeneration unit, a resource recovery unit and an automatic control unit which are communicated in sequence. The deep purification unit adopts at least two resin exchange towers connected in parallel and is filled with fluorine ion selective exchange resin; the regeneration unit realizes resin regeneration through closed-loop circulation of regeneration liquid between a resin tower and a regeneration liquid storage tank; and the resource recovery unit is used for conveying the fluorine ion-enriched regenerated waste liquid to a calcium fluoride production device. The method comprises the following steps: wastewater is pretreated and then enters a resin exchange tower for deep defluorination, and produced water is recycled; after the resin is saturated, a regeneration program is automatically switched and started, fluorine ions are eluted through cyclic regeneration, and finally the high-fluorine regenerated waste liquid is converted into a calcium fluoride product. The system provided by the invention realizes organic combination of deep purification of fluorine-containing wastewater and efficient recovery of fluorine resources, can continuously and automatically operate, and has the advantages of high treatment efficiency, low operation cost and environmental friendliness.

The present application provides an electrochemical sensor and a method for testing metal ions by using the same, and relates to the technical field of water quality testing. The electrochemical sensor provided by the present application includes: a sensor body; sensing electrodes arranged on a surface of the sensor body, the sensing electrodes including a testing electrode, a reference electrode and a hydrogen ion indication electrode; an ion permselective membrane covering a surface of at least one of the testing electrode and the hydrogen ion indication electrode. According to the present application, the ion permselective membrane on the sensor body filters corresponding target hydrogen or metal ions in a solution. The hydrogen ion indication electrode measures a pH value of the solution and calibrate the concentration of tested ions based on the pH value, to reduce the interference of the pH value of the solution on measurement. The testing electrode tests the concentration of metal ions and calibrates the concentration of tested ions, to reduce the interference of interference ions on the tested ions, thereby enhancing the testing accuracy and stability.

The invention discloses a biochar material for recycling rare and precious metals from waste solar cells and a preparation method of the biochar material, and relates to the technical field of biochar materials. When the biochar material for recycling the rare and precious metals from the waste solar cells is prepared, firstly, biomass raw materials are dried, smashed, carbonized and carboxylated, and then biochar is prepared; growing a metal organic framework on the surface of the biochar in situ to prepare metal organic framework modified biochar; enabling the metal organic framework modified biochar to react with paraformaldehyde and diethyl phosphite to prepare phosphating modified biochar; reacting the phosphatized modified biochar with 3-bromopropylene to obtain modified biochar; and coating the surface of the modified biochar with an ion imprinting layer to prepare the biochar material for recycling rare and noble metals from waste solar cells. The biochar material for recycling rare and precious metals from waste solar cells prepared by the invention has the advantages of selective ion adsorption, high adsorption capacity and recyclability.

The invention discloses a preparation method of a high-selectivity and high-pollution-resistance composite nanofiltration membrane based on in-situ hydrolysis-assisted interfacial polymerization (IP). According to the method, before an IP reaction process of piperazine (PIP) and 1, 3, 5-benzoyl chloride (TMC), controllable water is innovatively introduced into an organic phase to realize in-situ pre-hydrolysis of a monomer, then polymerization reaction kinetics and a film forming process are regulated and controlled, and a polyamide (PA) selection layer with an ultrathin and smooth structure and optimized pore size distribution is obtained. Compared with the prior art, the composite nanofiltration membrane prepared by the method has the advantages that the water flux and the monovalent / divalent anion selectivity are remarkably improved while the high divalent salt rejection rate is maintained, and the composite nanofiltration membrane has relatively high anti-pollution performance, breaks through the tradeoff limitation between permeability and selectivity in a traditional nanofiltration membrane, and is suitable for large-scale popularization and application. And the technical bottleneck of uneven distribution of a film surface structure and charges is effectively relieved. The technology is simple in process, mild in condition and good in repeatability, and has wide application prospects in the field of resource separation such as high-salinity wastewater salt recovery and salt lake lithium extraction.

The invention provides a method and equipment for extracting alkali metal from lithium precipitation waste. Relates to the field of alkali metal extraction, 0.0003 mol of ethidium bromide and 0.0002 mol of 1, 3, 5-triformyl phloroglucinol are respectively added into 7.5 mL of dimethyl sulfoxide, and ultrasonic treatment is performed for 10 minutes to obtain an aldehyde monomer solution and an amine monomer solution; and S2, slowly dropwise adding the aldehyde monomer solution into the amine monomer solution, stirring until the aldehyde monomer solution becomes dark red, and standing for 24 hours to obtain the porous organic framework nanosheets, the artificial cation-chloride ion co-transporter membrane has a porous organic framework with weak surface charges and narrow pores and high selectivity, and can be used for preparing the artificial cation-chloride ion co-transporter membrane. Basic ions and halogen ions Cl <-> can be identified, other cations and anions are repelled, and the size-induced ion selectivity is Cl <-> approximately equal to K + gt; na + gt; li + gt; gt; ca < 2 + > gt; mg < 2 + > has low permeability to Rb and Cs, the lithium ion permeability and the lithium extraction performance are improved by utilizing rich chloride ions in the lithium precipitation mother liquor, excessive waste liquid is not easy to generate, the selectivity is good, the process is fast, and the cost is low.

The invention discloses a preparation method and application of a monovalent cation selective membrane with an Al-MOF-based layered frame structure, and belongs to the technical field of membrane separation. The monovalent cation selective membrane solves the problems that the ion flux and the selectivity are difficult to consider, the structure of a separation layer is uneven, many polymerization defects exist in a frame pore channel, and the long-term use stability is poor in the existing monovalent cation selective membrane. The method comprises the following steps: preparing a hydrolyzed polyacrylonitrile basement membrane, preparing an Al-MOF modified basement membrane, and carrying out heat treatment and curing after interfacial polymerization reaction. The interfacial polymerization process is regulated and controlled through the confinement of an Al-MOF layered frame structure, a polyamide separation layer with high crosslinking degree, narrow pore size distribution and high positive charge density is cooperatively constructed in combination with a binary mixed amine monomer, the dual effects of electrostatic repulsion and size screening are synchronously enhanced, the Na < + > / Mg < 2 + > monovalent cation selectivity can reach 50.45 under the optimal condition, meanwhile, the high monovalent ion flux is maintained, and the specific surface area is increased. The membrane has excellent long-term operation stability and is suitable for separation of monovalent and multivalent cations in an electrodialysis system.

The application discloses a kind of based on shallow ground source heat regulation and control's electrodialysis salt lake lithium extraction and membrane pollution removal method, including ultra-shallow ground source heat pipe, surface ground source heat pipe, brine tank, fresh water tank, porous medium membrane and external circuit, wherein: using the heat of ultra-shallow ground source, surface ground source, respectively, fresh water tank and brine tank are heated or cooled, so that there is certain temperature difference between fresh water, brine, voltage is applied on the two sides of system, using electrodialysis process principle, lithium ion, magnesium ion in brine can be separated from original solution;Use specific cation selective exchange membrane, lithium ion is separated from lithium, magnesium mixed solution;Meanwhile, magnesium ion will adhere to cation selective exchange membrane and its ion channel, and form membrane blockage;At this time, remove electric field, based on Soret effect, magnesium ion will spontaneously migrate from high temperature side to low temperature side, and form no energy consumption membrane pollution removal.

The invention belongs to the field of adsorbents, and particularly relates to a rubidium and cesium ion selective adsorbent based on a bio-based porous carbon material and a synthesis method thereof.Biomass raw materials are smashed to be prepared into suspension liquid, the suspension liquid reacts with an activating agent, and a precursor is obtained; performing anaerobic calcination on the precursor to obtain a bio-based porous carbon material; heating the bio-based porous carbon material to 330-335 DEG C in an inert atmosphere, taking out the bio-based porous carbon material, and immediately reacting the bio-based porous carbon material with a cold ethanol water solution to obtain a modified bio-based porous carbon material; and dispersing the modified bio-based porous carbon material in a mixed aqueous solution containing transition metal salt and potassium ferrocyanide for reaction to obtain the rubidium and cesium ion selective adsorbent. The adsorption capacity retention rate of the adsorbent is not lower than 85% after five times of adsorption-desorption cycles in an ultrasonic-assisted desorption environment; after 8 times of adsorption-desorption cycles, the adsorption capacity retention rate is not less than 75%; and the cycle service life is long.

This invention belongs to the field of cation exchange membranes and discloses a method for preparing a monovalent selective cation exchange membrane coupled with dibenzo-18-crown-6 nanomaterials. Utilizing the interaction between amino and sulfonic acids, diaminodibenzo-18-crown-6 (A18C6) is first added to a polymer, where A18C6 is immobilized near the sulfonate group. Then, 2,5-dihydroxyterephthalaldehyde (DHTA) is added, thereby achieving the growth of nanomaterials with crown ether structures around the sulfonate group. The crown ether structure exhibits electrostatic interactions with alkali metals, and the forces differ depending on the metal. A18C6 exhibits different forces with K... + Na + Li + The strength of the interaction with Mg 2+ The monovalent selective cation exchange membrane prepared by this invention is suitable for electrodialysis processes due to the action of the force.

The present disclosure discloses a system and a method for solar-driven photothermal seawater desalination and ion electroosmosis power generation. In the system, a first reservoir is provided with a first electrode immersed in seawater; a second reservoir is connected to the first reservoir via a cation selective nanofilm; a third reservoir is provided with a second electrode immersed in seawater, and the third reservoir is connected to the second reservoir via an anion selective nanofilm; and an adjustable sun-visor shields the cation selective nanofilm to form a first preset part of solar illumination and shields the anion selective nanofilm to form a second preset part of the solar illumination. Therefore, the cation selective nanofilm and the anion selective nanofilm are each under an asymmetric illumination to generate a temperature gradient.

The invention relates to the technical field of nanofiltration membrane preparation and membrane separation, in particular to a double-ionic-liquid synergistic composite positive-electricity nanofiltration membrane as well as a preparation method and application thereof. The invention aims to solve the problems that the surface of the traditional polyamide nanofiltration membrane is negatively charged, and high separation selectivity and high flux are difficult to simultaneously consider. A high-hydrophilicity and strong-polarity intermediate layer formed by codeposition of tannic acid and [HEMIm] [BF4] is constructed on the surface of a porous filter membrane polymer matrix; then hydrophobic ionic liquid [C6mim] [Tf2N] is introduced into a water phase to form a phase state interface design, and the positively charged polyamide layer with positively charged surface, high permeability, uniform pore structure, high selectivity and excellent anti-pollution stability is prepared through coordinated regulation and control of two ends of interface wettability and monomer diffusion rate by two ionic liquids with different functions. The obtained membrane layer has a high rejection rate on divalent ions, and is suitable for selective separation of multivalent / monovalent ions in a high-salt system.

This invention relates to a quantitative method for polyion-selective electrodes, specifically a novel method for rapid, accurate, and sensitive quantification based on the initial potential change rate of a polyion-selective electrode. Using an all-solid-state ultrathin polymer membrane polyion-selective electrode as the working electrode, it is inserted into the sample to be tested, causing the target polyions to accumulate at the membrane interface, generating an initial potential change rate. The concentration of polyions in the sample is then obtained based on the corresponding value of the initial potential change rate of the sample on a standard curve. This novel quantitative method for polyion-selective electrodes developed in this invention has advantages such as simple operation, short detection time, low operating cost, and suitability for on-site detection. It is of great significance for the direct potential determination of polyions and for counterion determination, enzyme assays, and immunoassays using polyion electrodes as signal converters.

The present application belongs to the technical field of water treatment, and provides a method for selectively removing lead ions in perovskite solar cell leachate. The present application mixes the perovskite solar cell leachate with a pH regulator, and uses amyloid fibril-ceramic membrane for filtering treatment to complete the selective removal of lead ions in the perovskite solar cell leachate. The amyloid fibril-ceramic membrane is obtained by modifying the surface of a ceramic membrane with an interface regulator to make the surface of the ceramic membrane negatively charged, then applying an amyloid fibril solution on the surface of the ceramic membrane, and self-assembling a three-dimensional network structure functional layer under the driving of electrostatic interaction, and drying to obtain the amyloid fibril-ceramic membrane. The method for selectively removing lead ions can be carried out at room temperature, and has the advantages of simple process, low energy consumption, high efficient selective removal of lead ions in a complex system containing multiple metal ions and organic matters, removal rate of more than 99%, good anti-interference ability of coexisting ions and organic matters, and wide application prospect.

The present invention belongs to the field of cation exchange membranes and discloses a monovalent selective cation exchange membrane with crown ether encapsulated within the membrane and a preparation method thereof. First, a sulfonated chloromethylated polymer is synthesized and the solvent is evaporated to form a membrane. The chemical reaction between the chloromethyl groups contained in the membrane and the amine groups provides growth sites for the covalent organic framework. Subsequently, the covalent organic framework is constructed within the membrane channel by an in situ growth method, and the crown ether nanomaterial is encapsulated within the membrane. The regular porous channels of the covalent organic framework and the sulfonic acid groups in the base membrane act synergistically to ensure good ion flux of monovalent ions. At the same time, the crown ether structure has a special recognition and complexing effect on alkali metal ions and has different affinities for different metal ions, thereby achieving selective separation of monovalent cations. The monovalent selective cation exchange membrane prepared by the present invention is suitable for electrodialysis processes.

The invention belongs to the technical field of osmotic energy conversion membranes, and discloses an aramid nanofiber membrane material and a preparation method thereof. Comprising the following steps: uniformly coating a nylon plate with an aramid nanofiber dispersion liquid, and performing blade coating by using a scraper to obtain an initial aramid nanofiber membrane on the nylon plate; stripping the initial aramid fiber nanofiber membrane from the nylon plate to obtain a self-supporting initial aramid fiber nanofiber membrane; the self-supporting initial aramid nanofiber membrane is soaked in deionized water, and residual chemical reagents are removed; and drying the self-supporting initial aramid fiber nanofiber membrane to obtain the aramid fiber nanofiber membrane. Compared with the prior art, the mechanical property of the film is remarkably improved; excellent cation selectivity is shown; in addition, the film resistance is obviously reduced by controlling a scraper coating process; in the aspect of cost, the preparation process of the ANF membrane is simple, and the preparation of a large-area membrane can be easily realized.

The invention relates to an electrodialysis device and method for selectively synthesizing cobalt ferricyanate and efficiently extracting potassium and application. A membrane stack structure of the electrodialysis device sequentially comprises a first anion exchange membrane, a cation exchange membrane, a monovalent and divalent cation selective separation membrane and a second anion exchange membrane to form an anode chamber, a first raw material chamber, a product chamber, a second raw material chamber and a cathode chamber. Under the driving of a direct-current electric field, Co < 2 + > and [Fe (CN) 6] < 4-> are directionally migrated to a product chamber for reaction, and a CoHCF material with smooth surface, uniform size and high crystallinity is generated. The method effectively inhibits side reactions, and improves the purity and structural controllability of the material. The separation coefficient of the prepared CoHCF on K < + > in a high-sodium solution with the ratio of K < + > to Na < + > being 1: 30 reaches up to 13.05, and the CoHCF is suitable for efficient selective extraction of potassium resources in seawater and brine.

The invention relates to a resource recovery method of rare earth ammonium sulfate leaching wastewater, and a selective electrodialysis device comprises an anode chamber, at least one group of repeating unit chamber consisting of a desalination chamber and a concentration chamber, and a cathode chamber which are arranged in sequence; each repeating unit chamber is formed by separating a membrane unit consisting of an anion exchange membrane, a monovalent / multivalent cation selective separation membrane and an anion exchange membrane; the rare earth ammonium sulfate leaching wastewater comprises a mixed solution of rare earth sulfate and ammonium sulfate; rare earth ammonium sulfate leaching wastewater is introduced into a desalination chamber, rare earth ions are intercepted in the desalination chamber by a monovalent / multivalent cation selective separation membrane and an anion exchange membrane, and NH4 < + > and SO4 < 2-> enter a concentration chamber through the monovalent / multivalent cation selective separation membrane and the anion exchange membrane respectively. Rare earth ions and NH4 < + > are separated by virtue of the Donnan effect and size screening of a monovalent / multivalent cation selective separation membrane in the selective electrodialysis device, so that the resource recovery of the rare earth ammonium sulfate leaching wastewater is realized.

The present application relates to the field of adsorption materials and relates to a method for preparing a radionuclide ion absorption material, particularly a method for preparing a novel Cs ion selective adsorption material. This method is characterized by encapsulating fine hexacyanoferrate particles with highly selective adsorption capacity for Cs ions within a spherical carbon material. This significantly improves the uniform dispersibility and hydraulic properties of the hexacyanoferrate particles, effectively and selectively adsorbing Cs ions while avoiding the significant water resistance caused by the accumulation of hexacyanoferrate particles. Furthermore, because the spherical carbon material has a hard and dense spherical shell, it completely avoids material pulverization and debris loss, demonstrating excellent adsorption performance in the treatment of Cs-containing radioactive wastewater.

The invention relates to the technical field of ion exchange membranes, in particular to a zwitterionic conduction membrane containing a fluorine side chain as well as a preparation method and application of the zwitterionic conduction membrane. Under the catalysis of Lewis acid, a polymer main chain and fluorine-containing benzoyl chloride are subjected to Friedel-Crafts acylation reaction to obtain a polymer with a fluorine-containing side chain; the method comprises the following steps: carrying out nucleophilic aromatic substitution reaction on fluorine atoms activated by carbonyl on a fluorine-containing benzene ring and a hydroxyl-containing nidazole compound, and grafting a basic group; a nucleophilic ring-opening reaction is carried out on sultone by using tertiary nitrogen atoms on a nidazole ring, an amphoteric acid-base pair structure containing quaternary ammonium salt and sulfonic acid groups is obtained on a same side chain, and film casting is carried out. The fluorine-containing side chain is used as a chemically stable bridge and an efficient reaction activation point, and the prepared zwitterionic conduction membrane with the fluorine-containing side chain has high ionic conductivity, ionic selectivity and chemical stability, can be used in the fields of flow batteries, fuel cells, hydrogen production by electrolysis of water and the like, and has a good application prospect.

The invention provides a selective separation method for lithium ions and multivalent ions in a multi-ion coexistence system, belongs to the technical field of metal ion separation, and aims at solving the problem that multivalent metal ions are not fully utilized in an existing leaching solution lithium extraction method. The method comprises the following steps: adjusting the pH value of the multi-ion coexistence system containing at least one of Al < 3 + > and Fe < 3 + >, Li < + > and Mg < 2 + > to be 10-13; reacting for 20 minutes to 2 hours at the temperature of 25 to 80 DEG C to enable at least one of Al < 3 + > and Fe < 3 + > and Mg < 2 + > to generate a magnesium-based composite hydroxide precipitate; and carrying out solid-liquid separation, wherein the obtained magnesium-based composite hydroxide is used for deeply removing heavy metal ions in heavy metal-containing wastewater. The method is simple in process, lithium is extracted, and meanwhile high-value utilization of multivalent metal resources is achieved.

This invention discloses a MnO2 pseudocapacitive material containing cation vacancy defects, its preparation method, and its applications. In the preparation process, different types and amounts of pre-doped ions are introduced during hydrothermal treatment, followed by etching in acid and alkaline solutions. By optimizing the etching conditions, the pre-doped ions are selectively dissolved, forming cation vacancies in the MnO2 lattice, ultimately yielding the MnO2 pseudocapacitive material containing cation vacancy defects. The preparation method provided by this invention is characterized by its simple process, easily controllable reaction, and low cost, making it suitable for large-scale production of pseudocapacitive materials containing cation vacancy defects.

The invention provides a negatively charged enhanced nanofiltration membrane with uniform pore size as well as a preparation method and application thereof. The nanofiltration membrane comprises a supporting bottom membrane and an active separation layer loaded on the supporting bottom membrane, the active separation layer comprises an interfacial polymerization product of post-treated and modified polyamine and polyacyl chloride; the polyamine comprises polyamine containing double bonds and negatively charged functional groups and polyamine without double bonds and negatively charged functional groups; the post-treatment modification comprises grafting by using a functional monomer containing sulfydryl and a negatively charged functional group. The nanofiltration membrane has a larger pore diameter, narrower pore diameter distribution and enhanced electronegativity, and can improve the permeation flux of water and chloride ions, improve the salt separation efficiency and enhance the anti-scaling and anti-pollution capacities on the premise of not reducing the retention rate of Na2SO4. The nanofiltration membrane disclosed by the invention has high water flux, high sodium sulfate rejection rate and relatively high monovalent and bivalent anion selectivity, and has a wide application prospect in the zero discharge and recycling process of high-salinity wastewater.

The invention discloses a method for selectively detecting iodide ions through cathode photoelectrochemistry, and belongs to the technical field of analysis and detection. The method provided by the invention is a cathode photoelectrochemical detection method based on matched insertion induced symmetric breaking, and symmetric breaking can be induced by matching the diameter of the iodide ions with the interlayer spacing of BiOIO3 and embedding and fixing the iodide ions between layers, so that an enhanced polarized electric field and light current are obtained, and finally selective detection of the iodide ions is realized. According to the method, the problem that the anode is easily interfered by oxidation-reduction substances in a system during photoelectrochemical detection is avoided, the detection sensitivity is improved, the detection limit is reduced, and a new method for selective detection of iodide ions is developed.