Focused on the research and development and production of resin materials and resin end products - Hebei Lijiang
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AboutHebei Lijiang Biotechnology Co., Ltd. is a new material manufacturer specializing in the production of functional special ion exchange resins and disposable blood perfusion devices. It is a modern high-tech enterprise integrating the research and development, production, sales, and service of resin materials and resin end products. The company was established in April 2014 with a registered capital of 52 million yuan. It plans to cover an area of 267 acres and is located in the High-tech Industrial Park of Weixian County, Hebei Province—New Material Demonstration Park. The total investment is 510 million yuan. It is a council member unit of the Ion Exchange Resin Branch of the China Membrane Industry Association.
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Product
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BlogsThe company will focus on the high-end market, with the purpose of serving society, solidly carrying out technological innovation and product promotion, continuously improving the development and expansion of ion exchange resin products in emerging application fields, thereby promoting the upgrading and development of related industries.
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Company AlbumThe current phase of construction has been fully completed and put into operation, featuring a comprehensive workshop with 42 production lines for functional ion exchange resins with an annual output of 16,800 tons and a production capacity of 30,000 tons, a wastewater treatment plant with an annual treatment capacity of 403,000 tons, and a workshop producing 5,000 tons of medical-grade magnesium sulfate annually. Trial production began in July 2016, with official production starting in January 2017.
Oxidation and degradation of resin
Release Time:
2014-09-25
The chemical stability of resins can be represented by their ability to withstand oxidizing agents. Cation exchange resins mainly undergo backbone chain scission upon oxidation, while anion exchange resins primarily exhibit degradation of quaternary ammonium groups.
1. Oxidation of cation exchange resins:
Upon oxidation, cation exchange resins mainly experience backbone chain scission, producing low molecular weight sulfonated compounds and carboxyl groups. The reaction is as follows:
The oxidizing agent encountered by cation exchange resins is mainly oxygen generated by the reaction of free chlorine with water, as shown in the following reaction:
In the past, free chlorine in raw water mainly came from disinfection of domestic water. In recent years, due to increased organic content and bacteria in natural water, chlorination is also required before coagulation and clarification to achieve sterilization and reduce COD. Therefore, attention must be paid to the damage caused by free chlorine to cation exchange resins. During regeneration, if poor quality industrial hydrochloric acid or by-product hydrochloric acid containing oxidizing agents is used, it can also damage cation exchange resins. Generally, the free chlorine content in raw water entering chemical demineralization equipment should be less than 0.1 mg/L.
2. Methods to prevent oxidation of cation exchange resins:
(1) Activated carbon filtration. A common method to prevent oxidation of cation exchange resins is through activated carbon filtration. The principle of activated carbon removing free chlorine is not simply adsorption but a surface chemical reaction. When the chlorine adsorbed on the activated carbon surface reaches a certain concentration, the following reaction occurs:
In the formula: C* — activated carbon;
CO* — oxide formed on the surface of activated carbon.
If sufficient chlorine participates in the reaction, CO* can convert to CO or CO2 and escape, leaving the activated carbon to continue adsorbing free chlorine. Therefore, to remove free chlorine, a higher filtration velocity (about 50 m/h) can be used. At the same time, activated carbon has a high adsorption capacity for free chlorine (about 6.5 mg or more of Cl2 per gram of activated carbon).
The following empirical formula can be used to calculate the removal of free chlorine from water using activated carbon:
In the formula: CO — free chlorine content in influent water, mg/L;
C — free chlorine content in effluent water, mg/L;
L — height of activated carbon layer, m;
V — filtration velocity, m/h.
Considering the slower reaction rate of HOCl, the above formula is corrected as follows:
The raw materials used to manufacture activated carbon generally have no effect on dechlorination efficiency.
The presence of colloids or high concentrations of organic matter in water will severely shorten the lifespan of activated carbon as a dechlorination agent.
When activated carbon filters are used only for removing free chlorine, a leakage Cl2 amount ≥ 0.1 mg/L can be used as the endpoint. The lifespan of activated carbon is very long. For example, under conditions of 0.76 m activated carbon layer height and 6.1 m/h filtration velocity, dechlorinating water with 2 mg/L free chlorine content, the service life is about 6 years.
(2) Selecting cation exchange resins with high crosslinking degree. As the crosslinking degree of the resin increases, its oxidation resistance improves.
After oxidation, cation exchange resins become loose due to chain scission, resulting in volume expansion and increased water content. Macroporous cation exchange resins have high crosslinking degrees and better oxidation resistance. However, as the crosslinking degree increases, the exchange capacity decreases and the price rises, so they are rarely used in practice.
3. Degradation of strong base anion exchange resins:
Strong base anion exchange resins mainly exhibit gradual degradation of quaternary ammonium groups upon oxidation, without backbone chain scission. The degradation mainly involves sequential decomposition of quaternary ammonium groups into tertiary, secondary, primary amines, and even non-basic substances. In chemical demineralization processes, this mainly manifests as a reduction in neutral salt decomposition capacity, especially silica exchange capacity. The oxidizing agents encountered during operation are mainly dissolved oxygen in water, and during regeneration, oxidizing agents mainly include ClO3- and FeO42- contained in alkali.
The oxidation reaction of quaternary ammonium groups is shown in the following formula:
Strong base type I anion exchange resins have better oxidation resistance than type II. The exchange capacity of strong base anion exchange resins gradually decreases with long-term use.
4. Methods to prevent degradation of strong base anion exchange resins:
(1) Use vacuum degassers to reduce oxygen content in influent water to the anion bed.
(2) Perform corrosion protection on alkali storage and transportation equipment to reduce iron content in regeneration liquid.
(3) Use soda produced by diaphragm method to reduce NaClO3 content in alkali solution (can be reduced to 6-7 mg/L).
(4) Control regeneration liquid temperature: type I anion resins should not exceed 40°C; type II anion resins should not exceed 35°C.
(5) Resins should be stored in chloride form at low temperatures.
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24-05-14 14:37:56
