阅读说明：本技术 一种利用格氏废水制备镁基阻燃剂的方法 (Method for preparing magnesium-based flame retardant by utilizing Grignard wastewater ) 是由 吕亮 李建光 王玉林 徐继农 朱鹏江 谢作法 吴越超 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种利用格氏废水制备镁基阻燃剂的方法,包括：(l)向格氏废水中加入含铝化合物充分搅拌反应0.5-3 h,降低废水溶液的酸性,使pH值达到3-4,过滤,得到滤液,不溶物套用于下一批反应；(2)向步骤(1)得到的滤液中加入可溶性铝盐,搅拌溶解得镁铝双金属盐的混合溶液A,备用；(3)将碱性化合物配置成混合溶液B,备用；(4)将上述混合溶液A和混合溶液B快速混合共沉淀制得镁铝复合氢氧化物浆料,再经晶化、过滤、洗涤、干燥,得到镁基阻燃剂。本发明充分利用了格氏废水中的镁资源,得到的镁基阻燃剂具有广泛的用途,具有环境友好、经济效益好等优点。(The invention discloses a method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater, which comprises the following steps: (l) Adding an aluminum-containing compound into the Grignard wastewater, fully stirring and reacting for 0.5-3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, filtering to obtain a filtrate, and sleeving an insoluble substance for the next batch of reaction; (2) adding soluble aluminum salt into the filtrate obtained in the step (1), stirring and dissolving to obtain a mixed solution A of magnesium aluminum double metal salt for later use; (3) preparing an alkaline compound into a mixed solution B for later use; (4) and quickly mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, and then crystallizing, filtering, washing and drying to obtain the magnesium-based flame retardant. The invention fully utilizes the magnesium resource in the Grignard wastewater, and the obtained magnesium-based flame retardant has wide application, and has the advantages of environmental friendliness, good economic benefit and the like.)

1. The method for preparing the magnesium-based flame retardant by utilizing the Grignard wastewater is characterized by comprising the following steps of:

(l) Adding an aluminum-containing compound into the Grignard wastewater, reacting for 0.5-3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, filtering to obtain a filtrate, wherein insoluble substances can be used for the next batch of reaction;

(2) adding soluble aluminum salt into the filtrate obtained in the step (1), stirring and dissolving to obtain a mixed solution A of magnesium aluminum double metal salt for later use;

(3) preparing an alkaline compound into a mixed solution B for later use;

(4) and mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, and then crystallizing, filtering, washing and drying to obtain the magnesium-based flame retardant.

2. The method for preparing a magnesium-based flame retardant by using Grignard wastewater as claimed in claim 1, wherein the aluminum-containing compound in the step (1) is one or two of pseudo-boehmite, aluminum hydroxide and aluminum trioxide.

3. The method for preparing a magnesium-based flame retardant using Grignard wastewater as claimed in claim 1, wherein the soluble aluminum salt in the step (2) is one or two of aluminum chloride, aluminum nitrate, aluminum sulfate and sodium metaaluminate.

4. The method for preparing a magnesium-based flame retardant using Grignard waste water according to claim 1, wherein the molar ratio of the aluminum ions to the magnesium ions in the mixed solution A in the step (2) is 0.25-0.5: 1.

5. The method for preparing magnesium-based flame retardant by using Grignard waste water, as claimed in claim 1, wherein the alkaline compound in the step (3) is sodium hydroxide or sodium carbonate or a mixture of the two, and the molar ratio of the sodium carbonate to the sodium hydroxide in the mixture is 0.5:1-2: 1.

6. The method for preparing a magnesium-based flame retardant using Grignard waste water according to claim 1, wherein the molar ratio of the sum of magnesium and aluminum ions in the mixed solution A to the sum of anions in the mixed solution B in the step (4) is 1:1 to 1: 4.

7. The method for preparing magnesium-based flame retardant by using Grignard waste water, as claimed in claim 1, wherein the crystallization temperature in the step (4) is 60-100 ℃, and the crystallization time is 3-36 h.

Technical Field

The invention belongs to the field of wastewater resource utilization, and particularly relates to a method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater.

Background

Alkyl magnesium halide, also known as grignard reagent, is a good reagent in organic synthesis, and is prepared by adding halide and magnesium metal into anhydrous ether or Tetrahydrofuran (THF) which is usually used as a solvent, and is widely applied to synthesis of products with high added values, such as medicines, spices, special organosilicon monomers and the like, and the related reaction is called grignard reaction. A large amount of reaction wastewater can be formed in the Grignard reaction process, the wastewater contains a large amount of magnesium ions, hydrogen ions, halide ions and the like, the wastewater has strong acid property, environmental pollution can be caused by everywhere dumping, the acidity and alkalinity of soil can be influenced by the large amount of dumping, the soil property of the soil is changed, and the water quality can be greatly changed. Alkyl magnesium bromide and alkyl magnesium iodide in the Grignard reagent are converted into magnesium bromide and magnesium iodide after reaction, because bromine and iodine have higher values, bromide ions and iodide ions are converted into bromine simple substances or iodine simple substances by oxidation reaction and are recovered, and chloride ions have no recovery value, so that general enterprises discharge the waste water, but the waste water has high salt content, partial organic matters are dissolved, the COD content is high, the biodegradability is low, and the treatment difficulty is high. The magnesium salt content in the waste water is about 20-30%, and the direct discharge causes serious environmental pollution and waste of magnesium resources.

At present, few research reports aiming at resource utilization of magnesium ions in Grignard wastewater are limited to concentration to obtain magnesium salts or precipitation separation by adding alkali.

For example, CN1648065A discloses recovering magnesium ions by generating magnesium sulfate, which requires concentrating a large amount of wastewater and then adding concentrated sulfuric acid to generate magnesium sulfate, which requires high energy consumption, and causes severe corrosion to equipment.

And CN101130485A discloses that magnesium ions are recovered by generating magnesium chloride, the magnesium chloride is water-soluble salt, the wastewater needs to be completely evaporated to dryness, the energy consumption is high, and meanwhile, the obtained magnesium chloride is often carried with organic impurities, and the use of the magnesium chloride is limited due to low purity.

For example, CN101665258A discloses a process for recovering magnesium salts from grignard waste water, in which alkali metal hydroxide is used to adjust the pH of the waste water, and then carbonate is added to perform precipitation to obtain basic magnesium carbonate, thereby avoiding the problem of difficult solid-liquid separation of magnesium hydroxide colloidal precipitate formed by direct precipitation.

From the research results reported in the prior art, the method focuses on how to precipitate or evaporate magnesium ions to obtain a crude magnesium salt product, does not fully consider the final use and product value of the obtained product, and has little practical significance. Therefore, it is very urgent to develop a method for efficiently utilizing magnesium resources in grignard wastewater. If magnesium ions in the Grignard waste water are prepared into the magnesium-aluminum composite hydroxide, the magnesium-aluminum composite hydroxide has wide application, particularly has good characteristics on flame retardance of polyolefin, and has huge market prospect along with non-halogenation application and popularization of the flame retardant.

Aiming at the technical problems in the prior art, the invention provides a method for efficiently utilizing magnesium resources in Grignard waste water, which converts magnesium salts in the Grignard waste water into a magnesium-based flame retardant with wide application, has the advantages of low alkali consumption, low cost and high product added value, reduces the salt concentration in the waste water and improves the biodegradability while obtaining the magnesium-based flame retardant, and can be simply and conveniently treated to reach the emission standard.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the method for preparing the magnesium-based flame retardant by utilizing the Grignard wastewater, which has the advantages of simple process, low cost, good economic benefit and good treatment effect.

The technical scheme adopted by the invention is as follows: a method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater comprises the following steps:

(l) Adding an aluminum-containing compound into the Grignard wastewater, reacting for 0.5-3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, filtering to obtain a filtrate, wherein insoluble substances can be used for the next batch of reaction;

(2) adding soluble aluminum salt into the filtrate obtained in the step (1), stirring and dissolving to obtain a mixed solution A of magnesium aluminum double metal salt for later use;

(3) preparing an alkaline compound into a mixed solution B for later use;

(4) and mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, and then crystallizing, filtering, washing and drying to obtain the magnesium-based flame retardant.

Preferably, the aluminum-containing compound in the step (1) is one or two of pseudo-boehmite, aluminum hydroxide and aluminum trioxide.

Preferably, the soluble aluminum salt in step (2) is one or two of aluminum chloride, aluminum nitrate, aluminum sulfate and sodium metaaluminate.

Preferably, the molar ratio of the aluminum ions to the magnesium ions in the mixed solution a in the step (2) is 0.25 to 0.5: 1.

preferably, the alkaline compound in step (3) is sodium hydroxide or sodium carbonate or a mixture of the two, and the molar ratio of sodium carbonate to sodium hydroxide in the mixture is 0.5:1-2: 1.

Preferably, the molar ratio of the sum of magnesium and aluminum ions in the mixed solution A to the sum of anions in the mixed solution B in the step (4) is 1:1-1: 4.

Preferably, the crystallization temperature in the step (4) is 60-100 ℃, and the crystallization time is 3-36 h.

The method converts the magnesium salt in the Grignard wastewater into the magnesium-based flame retardant with wide application, reduces the salt concentration in the wastewater while obtaining the magnesium-based flame retardant, improves the biodegradability, can simply and conveniently treat the magnesium-based flame retardant to reach the emission standard, and has the advantages of low alkali consumption, low cost and high added value of products.

Compared with the prior art, the invention has the following advantages:

1. the method has good economic benefit, the magnesium salt in the Grignard wastewater is converted into the magnesium-based flame retardant with wide application by adopting a coprecipitation method, the added value of the product is high, waste is changed into valuable, waste utilization is realized, and good economic benefit is generated;

2. the method is green and environment-friendly, reduces the salt concentration in the wastewater and improves the biodegradability while obtaining the magnesium-based flame retardant, and can be simply and conveniently treated to reach the emission standard.

Detailed Description

The present invention is described in further detail below with reference to specific examples, but the scope of the present invention is not limited thereto.

Mg in Grignard reaction wastewater used in examples²⁺The content of (b) is 3.0mol/L, and the pH value is-0.48.

Example 1

A method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater comprises the following steps:

(1) adding 15.6g of aluminum hydroxide into 200ml of Grignard wastewater, fully stirring for reaction for 3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, and filtering out 3.9g of insoluble substances which can be used in the next batch of reaction;

(2) adding 12.07g of aluminum chloride hexahydrate into the filtrate obtained in the step (1) to obtain a mixed solution A, and adding Mg into the mixed solution A²⁺With Al³⁺In a molar ratio of 3: 1;

(3) adding 58.3 g of sodium carbonate and 22g of sodium hydroxide into 200ml of water to prepare an alkaline mixed solution B;

(4) and quickly mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the slurry at 65 ℃ for crystallization for 24 hours, centrifugally filtering, washing and drying to obtain 60.2g of magnesium-based flame retardant with the magnesium-aluminum ratio of 3: 1.

Example 2

A method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater comprises the following steps:

(1) adding 15.6g of pseudo-boehmite into 200ml of Grignard wastewater, fully stirring for reaction for 3 h, reducing the acidity of the wastewater solution to enable the pH value to reach 3-4, and filtering out 1.56g of insoluble substances to be applied to the next batch of reaction;

(2) 45.01g of aluminum nitrate nonahydrate was added to the filtrate obtained in step (1) to obtain a mixed solution A, and Mg was added to the mixed solution A²⁺With Al³⁺In a molar ratio of 2: 1;

(3) adding 15.9 g of sodium carbonate and 36g of sodium hydroxide into 200ml of water to prepare an alkaline mixed solution B;

(4) and quickly mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the temperature of 65 ℃ for crystallization for 24 hours, centrifugally filtering, washing and drying to obtain 83.7g of the magnesium-based flame retardant with the magnesium-aluminum ratio of 3.

Example 3

A method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater comprises the following steps:

(1) adding 7.65g of aluminum oxide into 200ml of Grignard wastewater, fully stirring for reaction for 3 h, reducing the acidity of the wastewater solution to enable the pH value to reach 3-4, and filtering out 3.05g of insoluble substances for the next batch of reaction;

(2) adding 14.48g of aluminum chloride hexahydrate into the filtrate obtained in the step (1) to obtain a mixed solution A, and adding Mg into the mixed solution A²⁺With Al³⁺In a molar ratio of 4: 1;

(3) adding 30.9 g of sodium carbonate and 30g of sodium hydroxide into 200ml of water to prepare an alkaline mixed solution B;

(4) and quickly mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the mixed solution at 80 ℃ for crystallization for 16 hours, and centrifugally filtering, washing and drying to obtain 50.4g of magnesium-based flame retardant with the magnesium-aluminum ratio of 4.

Example 4

A method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater comprises the following steps:

(1) adding 62.4g of aluminum hydroxide into 1L of Grignard wastewater, fully stirring and reacting for 3 hours, and reducing the acidity of the wastewater solution to ensure that the pH value reaches 3-4;

(2) adding 74.36g of aluminum chloride hexahydrate into the filtrate obtained in the step (1) to obtain a mixed solution A, and enabling Mg in the mixed solution A to be contained²⁺With Al³⁺In a molar ratio of 3: 1;

(3) adding 128g of sodium hydroxide into 1L of water to prepare a mixed solution B;

(4) and (3) quickly mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the mixed solution at 90 ℃ for crystallization for 12 hours, and centrifugally filtering, washing and drying to obtain 410.8g of the magnesium-based flame retardant with the magnesium-aluminum ratio of 3.

Example 5

A method for preparing a magnesium-based flame retardant by utilizing Grignard wastewater comprises the following steps:

(1) adding 4.68Kg of pseudoboehmite and 1.23Kg of sodium metaaluminate into 100L of Grignard wastewater, stirring and dissolving uniformly to obtain a mixed solution A, wherein Mg in the mixed solution A is²⁺With Al³⁺In a molar ratio of 4: 1;

(2) adding 23.2Kg of sodium hydroxide into 100L of water to prepare a mixed solution B for later use;

(3) and quickly mixing and coprecipitating the mixed solution A and the mixed solution B to prepare magnesium-aluminum composite hydroxide slurry, keeping the temperature of 100 ℃ for crystallization for 6 hours, filtering the reaction solution, washing a filter cake to be alkalescent or neutral by pure water, and drying to obtain 10.2Kg of magnesium-based flame retardant with the magnesium-aluminum ratio of 4.