Ion exchange resin is a kind of high molecular compound, with active groups with exchange ions, it has a network structure and is insoluble. Ion exchange resins have the functions of separation, recovery, purification, and purification, and are used in various industries.
1. The functional role of ion exchange resin in the treatment of mercury-containing wastewater
Mercury-containing wastewater is one of the most harmful industrial wastewaters. The ion exchange resin method is suitable for the treatment of wastewater with low concentration, large discharge, and toxic metals. The resin exchange method is used to remove mercury as the secondary treatment system of the chemical method to ensure that Discharge standards, and can achieve a closed cycle, continuous and stable operation, the discharged wastewater can be reused as cooling water; the production capacity is improved, the unit product cost is reduced, and the treatment cost is saved; the application of the resin exchange method can also reduce the wastewater By the time of decolorization, the treated water is clear and transparent; the resin after failure is no longer recycled, and mercury is recycled as mercury waste residue, preventing secondary pollution. Therefore, the application of ion exchange method to treat low-concentration mercury-containing wastewater has obvious social and economic benefits.
2. The functional role of ion exchange resins in medicine
1. Refining and purification of drugs
The refining and purification of medicines is to convert the active ingredients in the medicinal solution into ionic form, ion exchange with the resin, adsorb the active ingredients, use the principle of acid-base salt formation to convert the active ingredients into salts, and then elute; The effective ingredients of low and medium concentration are eluted after being adsorbed on the column to increase the content of effective ingredients to achieve the purpose of purification and purification. Its application is mainly antibiotics, and it is also widely used in other types of drugs.
2, drug resin targeted drug delivery system
ion exchange resins can be used for targeted drug delivery in addition to oral drug resin sustained and controlled release systems. In recent years, more and more clinical studies have shown that the selectivity of anti-tumor drugs is not high, which limits the further development of drug effects. Therefore, targeting systems that selectively deliver drugs to specific sites to increase local drug concentration and reduce systemic toxicity and adverse reactions have received increasing attention. The targeted drug delivery system is composed of drugs and carriers. Common carriers include microspheres, liposomes, monoclonal antibodies, double emulsions, and cell carriers. The use of ion exchange principles can make drugs into non-biodegradable pharmaceutical resin micro ball.
It is generally believed that the retention of particles with a particle size greater than 50 μm in the target tissue is less than that of particles with a smaller particle size. Therefore, an ion exchange resin with a suitable degree of crosslinking and pore size can be selected according to the nature of the drug to prepare the corresponding drug resin microspheres. Since the ion species and intensity in the blood are relatively constant and the volume of the resin microspheres is relatively small, the drug resin microspheres can be injected intravenously and combined with γ-scintigraphy technology to evaluate their targeting. Pore size is the rate-limiting factor for ion diffusion in the resin, and affects its targeting to tissues and drug release behavior in target tissues.
3, medical hygiene
The ion exchange resin itself can be taken orally as a medicament, which has the effects of detoxification, laxative, and deacidification. It can be used to treat gastric ulcers, promote appetite, and remove intestinal radioactive substances. For external application, ion exchange resin powder can be used to prepare ointments, powders and Baby skin care products, used to absorb wound poison and as an antidote. Adsorbing various drugs on the ion exchange resin can effectively control the drug release rate, prolong the drug effect, and reduce the number of medications; take advantage of the rapid expansion of the volume after the ion exchange resin absorbs water, and mix it with the drug to make a tablet. It can quickly swell and disintegrate, and can play the role of drugs faster and better.
Ion exchange resin is also an important agent for medical diagnosis and drug analysis and verification, such as blood component analysis, gastric juice verification, and drug component analysis. It has the advantages of fast detection speed and less interference.
3. The function of ion exchange resin in catalyst
1, acylation, alkylation
Acylation and alkylation reactions are an important type of organic synthesis reaction. Friedel-Crafts reactions generally use traditional catalysts, such as Lewis acid, AlCl3 and FeCl3, etc. The use of solid catalysts such as zeolites and ion exchange resins to replace traditional catalysts is a breakthrough in aromatic ring alkylation and acylation reactions. Since ion exchange resin has the advantage of being recyclable, it has been used more and more in alkylation and acylation reactions in recent years.
2, epoxidation reaction and ring opening reaction
The oxidant for the olefin epoxidation reaction is generally hydrogen peroxide or organic peroxides, such as tert-butyl peroxide and cumyl peroxide. Ion exchange resins are used as catalysts, and anion exchange resins supported by tungsten and molybdenum are generally used. For the catalyst. As an electrophile, the epoxy compound can be ring-opened by the anionic nucleophile of the basic resin, or react with neutral molecules with the help of acidic resin protons. Anion exchange resin in the form of bicarbonate can be used as a catalyst to prepare ethylene glycol by hydrolysis of ethylene oxide. The reaction of epoxide hydrolysis to glycol can also use quaternary phosphorus exchange resin instead of quaternary ammonium salt exchange resin as a catalyst. Vegetable oil epoxides can open the ring in acetic acid, but the conversion rate of epoxides is very low.
Fourth, the functional role of ion exchange resins in chemical processes
In chemical production, ion exchange resin technology is replacing some processes such as precipitation, solvent extraction and distillation. Initially applied ion exchange resins to chemical processes, mainly using batch-type fixed bed technology, and then further developed continuous application systems, such as Higgins Loo p and Himsley tower technology systems and ISEP continuous systems; in Higgins Loo p and Himsley systems The resin moves in the tower, but it is fixed in the ISEP system, which can reduce the degradation rate of the resin and extend the operating life. Compared with the fixed bed system, the ISEP system reduces investment by 20-40%, requires only 40-50% or less resin, and saves land. In some cases, it can also reduce the volume of pollution by 60-80%. For example, in the treatment of surface water permanganate, the ISEP system reduces salt loss to 1%; while the fixed bed system can only reduce it to 5%. At present, 70% of lysine in the world is produced by ISEP technology, and the annual growth rate of this technology in this field is 10-15%. In industrial separation and purification applications, synergy is the goal of application development. At present, in some devices, ion exchange removes non-polar organics, such as perchloroethane, and ion exchange resins are used to remove polar pollutants, such as permanganate.
5. The functional role of ion exchange resins in the food industry
MSG is a commonly used condiment, mainly made from corn fermentation broth through the action of microorganisms. During fermentation, a stock solution containing 2%-5% of glutamic acid is obtained, which can be extracted by ion resin method. When the pH is 5, sulfonic acid type strong acid ion resin is used for dynamic extraction, and the recovery rate of glutamic acid is 80%-90%. The study found that the macroporous ionic resin prepared by the copolymerization of acrylonitrile, butadiene and divinylbenzene with gasoline as the porogen can be used more than 200 times, and the elution peaks are relatively concentrated.
2. Extraction of natural sweeteners
The glycyrrhizic acid contained in the traditional Chinese herbal medicine licorice is an important sweetener and can be used in the food and pharmaceutical industries. The licorice is extracted with water, acid and alcohol to obtain a crude product containing 40% glycyrrhizic acid. After the crude product is dissolved in water, it passes through an exchange column equipped with an adsorption resin. The glycyrrhizic acid is adsorbed by the resin and then eluted with ethanol. After being concentrated by evaporation, a refined glycyrrhizic acid content of 91% can be obtained. Anion and cation exchange resins, adsorption resins and chelating resins are also widely used internationally to extract stevia from the stevia extract.
3. Separation and purification of amino acids and proteins
According to the different isoelectric points of amino acids, select the appropriate pH value. Ion exchange resins can be used (strong acid cation resins are used to separate them. Proteins are composed of amino acids. They can also be separated by ion exchange resins according to their isoelectric points.
VI. The functional role of ion exchange resins in metallurgical beneficiation
Ion exchange is one of the important unit operations in the metallurgical industry. It plays a very important role in the separation, purification and recovery of uranium, thorium and other transuranic elements, rare earth metals, heavy metals, light metals, precious metals and transition metals. Separation, enrichment, purification and recovery of uranium in the mine, separation and purification of rare earth elements and precious metals, recovery of chromium in electroplating solution and copper in rayon waste liquid; ion exchange resins can also be used in beneficiation-added to ore pulp The ion exchange resin can change the ion composition of the water in the slurry, make the flotation agent more conducive to the adsorption of the required metals, and improve the beneficiation and efficiency of the flotation agent.
Seven, the functional role of ion exchange resins in the atomic energy industry
The application of ion exchange resins in the nuclear energy industry includes the separation, purification, refining, and recovery of nuclear fuels. The use of ion exchange resins to prepare high-purity water is the only means of circulating, cooling, and supply water for nuclear power. Ion exchange resins are also nuclear industrial wastewater. The main method to remove radioactive contamination.
8. The functional role of ion exchange resins in the utilization of marine resources
Ion exchange resin can be used to extract important chemical raw materials such as iodine, bromine and magnesium from many marine organisms (such as kelp). In ocean navigation and islands, it is very economical and convenient to use ion exchange resin to produce fresh water from sea water.
Nine, the functional role of ion exchange resin in environmental protection
Ion exchange resin has important functions in the concentration, treatment, separation, recovery and analysis of waste water and waste gas. It has been widely used in the treatment of electroplating wastewater, papermaking wastewater, mining wastewater, domestic sewage, film processing wastewater, industrial waste gas, etc. . For example, the silver in the film processing wastewater is in the form of Ag(SO3)23- and other anions. After treatment with Type I strong alkaline ion exchange resin, the recovery rate of silver can reach more than 90%, which saves a lot of money. It also makes the wastewater meet the discharge standard; another example is the electroplating wastewater contains a large amount of toxic metal cyanide, such as Fe(CN)63-, Fe(CN)64-, etc., using polyacrylamide anion exchange with strong resistance to organic pollution After resin treatment, the content of metal cyanide can be reduced to less than 10 ppm.
10. The functional role of ion exchange resins in high-tech
The many functions of ion exchange resins are detailed above. Ion exchange resins have many functions and types, including strong acid cation exchange resin, weak acid cation exchange resin, strong basic anion exchange resin and weakly basic anion exchange resin. It is widely used in water treatment.