What are the common extractants? How many common extraction methods are there?

Common extractants:

1. Organic extractants: benzene, carbon tetrachloride, alcohol, kerosene, straight-run gasoline, hexane, cyclohexane, ......

2. Inorganic extractant: water is the cheapest and most easily available extractant.

Common extractants, carbon tetrachloride.

It is very stable in nature. It does not have any effect on the extractable, and it is a good extractant.

Neutral organic compounds such as alcohols, ethers, ketones, esters, amides, thioethers, sulfoxides and crown ethers are neutral extractants. Also included in this group of esters are carboxylic esters (e.g., ethyl acetate) and phosphine (e.g., tributyl phosphate), which are generally neutral in water.

Carboxylic acids, sulfonic acids and organophosphonic acids are acidic extractants, which are acidic in water and can ionize hydrogen ions.

Primary amines, secondary amines, tertiary amines and quaternary amines are alkaline extractants, these organic amines can add hydrogen ions in water, showing alkalinity, and their alkalinity is generally stronger than that of inorganic ammonia, while quaternary amines have strong alkaline properties.

Extractants for extracting tin:

A commonly used extraction method is to extract tin by adding an organic solvent containing inorganic acids and complexing agents to the water sample. in the form of organotins.

Tin is usually extracted from the sample by adding hydrochloric acid and extracting it with a solvent after shaking or ultrasonic**. In addition, the ion-pairing effect can be enhanced, and the extraction efficiency of organotins such as butyltin can be effectively improved. Commonly used extractants are methylene chloride, pentane, hexane, isooctane, ethyl acetate, benzene, toluene, ether.

Commonly used polar solvents are acetic acid solution and hydrochloric acid or acetic acid and polar solvent mixed solution, such as hydrochloric acid and methanol, hydrochloric acid and acetone, and a mixture of polar solvent and non-polar solvent, such as dichloromethane and methanol. In most cases, some solid samples are extracted with acids or polar solvents followed by immiscible solvents, which can extract organotins from the original extract.

The solubility of organotins in organic solvents can be increased by using cycloheptene trienolone or salt dissolution effect, and the extraction rate can be improved.

Tin, a metallic element, a low-melting metallic element with a bluish-white sheen, is divalent or tetravalent within the compound, is not oxidized by air, and is mainly found in the form of dioxide (cassiterite) and various sulfides (e.g., thiossiterite). Element symbol sn. Tin is one of the famous "hardware" - gold, silver, copper, iron, and tin.

Tin has been discovered and used since ancient times. In some ancient tombs in our country, some tin pots, tin candlesticks and other tin utensils are often excavated. According to research, during the Zhou Dynasty in China, the use of tin ware was very common.

In ancient tombs in Egypt, daily necessities made of tin have also been found.

1. Extraction method:

The immersion method is also known as the immersion method. For the extraction of a substance from a solid mixture or organism, the extraction agent used should be able to dissolve the extracted substance in large quantities without destroying the properties of the extracted substance.

2. Solvent extraction:

Solvent extraction is used to extract a component from a solution, and use the different partition coefficients of the component in two immiscible reagents to transfer it from one solution to another, so as to separate from other components to achieve the purpose of separation and enrichment.

3. Salting-out method.

Adding some inorganic salt to the solution makes the solubility of the solute in the original solvent greatly reduced, and precipitates out of the solution, this method is called salting-out. For example, a large amount of salts (ammonium sulfate) are added to the protein solution, especially heavy metal salts, so that the protein is precipitated out of the solution.

4. Extraction method.

Extraction is a unit operation that uses the principle of similar dissolution to separate mixtures by different components in the system with different solubility in solvents, and can be divided into extraction method (solid-liquid extraction) and extraction method (liquid-liquid extraction) according to the different components extracted. Extraction method (liquid-liquid extraction method): the extracted components are separated by different partition coefficients in two solvents that are immiscible with each other.

5. Decompression concentration method.

Some components to be tested are thermally unstable and easy to decompose at higher temperatures, and the use of reduced pressure concentration reduces the boiling point of the solvent, which can not only quickly concentrate to the required volume, but also avoid the decomposition of the analyte.

The commonly used decompression concentrator is the all-glass decompression concentrator, also known as the K-D concentrator, which is a commonly used decompression distillation device, which has the characteristics of low concentration temperature, fast speed, less loss and easy control of the required volume, and is suitable for the concentration of thermally unstable analyte extracts, especially for the concentration of sample solutions in the analysis of pesticide residues. In addition, it can also be used for purification and distillation of solvents.

Ethanol, petroleum ether and carbon tetrachloride can be used for extraction and washing according to the polarity of the target sample, with the exception of a few special types such as liquid bromine and dimethicone. The polar ones are alcohols and alcohol ethers, and the non-polar ones are ester ketones or aromatic hydrocarbons.

The main thing is that the solute is easily soluble in the organic solvent of the rotten stove, and a certain substance can be competed for from the solvent with a low degree of dissolution, such as CCL4 can extract the iodine element in the water, as well as wine and essence, acetone, etc., can be used as an extractant.

Carbon tetrachloride and benzene can be smooth, but the liquid depends on what is extracted, and the extraction of orange and blue wax is mainly based on the different solubility of solutes in different solutions, such as bromine, which has a lower solubility in water than in benzene, and can be extracted with benzene.

Extraction, also known as solvent extraction or liquid-liquid extraction (to distinguish it from solid-liquid extraction, i.e., leaching), also known as extraction (commonly used in the petroleum refining industry), is a kind of mass transfer separation process that uses liquid extractants to treat immiscible two-component or multi-component solutions with them to achieve component separation, and is a widely used unit operation. Using the principle of similarity dissolution, there are two ways of extraction:

Liquid-liquid extraction, the separation of a component of a liquid mixture with a selected solvent that is incompatible with the liquid of the extracted mixture, has selective solubility, and must have good thermal and chemical stability, as well as little toxicity and corrosiveness. For example, benzene is used to separate phenols in coal tar; separation of olefins from petroleum fractions with organic solvents; Br2 in water was extracted with CCL4

Solid-liquid extraction, also known as leaching, uses solvents to separate components in a solid mixture, such as sugars in sugar beets with water; Soybean oil in soybeans is soaked with alcohol to increase oil yield; Extracting the active ingredient from Chinese medicine with water to make a flow extract is called "leaching" or "leaching".

Although extraction is often used in chemical experiments, its operation does not cause a change in the chemical composition (or chemical reaction) of the extracted substance, so the extraction operation is a physical process.

Extraction is one of the methods used in organic chemistry laboratories to purify and purify compounds. By extraction, the desired compound can be extracted from a mixture of solids or liquids.

Extraction is divided into physical extraction and chemical extraction.

Physical extraction refers to the distribution of only the extractable in two solvents that are immiscible with each other during the extraction process, and no chemical reaction occurs, such as the extraction of iodine from water by CCL4.

Chemical extraction is also accompanied by a chemical reaction, through which the extractant reacts with the extractable to change the solubility and then achieve extraction.

The organic extractant is obviously an organic substance, which can react with the target substance during the extraction process to form compounds that are insoluble in water dust rock or soluble in the solvent of jujube liquid machine.

Let's illustrate with an example:

Fe(3+) is difficult to get into organic matter, but let it form [FeCl4](-Just increase the concentration of Cl(-) in the solution.

Then use a long-chain organic amine, abbreviated as RNH2, which is an organic extractant, because of the long carbon chain of R, it has relatively little solubility in water and large solubility in organic solvents. However, the NH2 group is highly hydrophilic, and it will be enriched at the interface between the organic and aqueous phases. Under acidic conditions, RNH2 becomes RNH3(+) and it forms an ion pair with [FeCl4](-, which pulls [FeCl4](- into the organic solvent to complete the extraction.

Makes it possible to present [FeCl4](-) in organic solvents.

RNH2 is one of many organic extractants.