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Anionic surfactants |
Sodium dodecyl sulfate is an anionic surfactant, and is a typical representative of sulphate-based surfactant. It is abbreviated as SDS, and also known as AS, K12, coco alcohol sulfate, sodium lauryl sulfate and foaming agent. The commercial products are usually white to light yellow crystalline powder. It is non-toxic, slightly soluble in alcohol, insoluble in chloroform and ether, soluble in water, and has good anionic and nonionic complex compatibility. It has good emulsibility, foamability, and foaming, infiltrating, decontaminating and dispersing properties. It is abundant in foams and quickly biodegradable, and has solubility next only to fatty alcohol polyoxyethylene ether sodium sulphate (abbreviated as AES). It is not sensitive to alkali and hard water, but its stability is inferior to general sulfonate under acidic conditions and is close to AES. It is not favorable to exceed 95 °C upon long-term heating, and its irritation is at the middle level among surfactants, with an irritation index of 3.3 for a 10% solution, which is higher than AES and lower than sodium dodecyl benzene sulfonate (abbreviated as LAS). Toxicity LD50 is 1300mg/kg. There is no evidence that this product is carcinogenic, but high doses may indeed irritate the skin. However, in general sanitary products the concentration is limited when used as a forming agent, and is in line with national standards. So there is no need to concern.
Sodium dodecyl sulfate is a major component of detergent. It is usually used in the DNA extraction process to separate DNA after protein denaturation. It is often misread as sodium dodecyl sulfonate. It is widely used as a foaming agent in toothpaste, soap, shower gel, shampoo, detergent and cosmetics. 95% of personal care products and household cleaning products contain sodium lauryl sulfate.
The above information is edited by the chemicalbook of Jin Yinxue. |
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Toxicity |
It can be safely used for food, but the content of sodium lauryl sulfate should not be less than 90% (FDA, §172.822, 2000). LD50 is 1288mg / kg (rat, oral). |
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Sodium dodecyl sulfonate |
There is certain universality of confusion and misuse for them, both of which belong to the anionic surfactants and the English abbreviations are both SDS. Sodium dodecyl sulfate (abbreviated as SDS) is also called sodium lauryl sulfate (abbreviated as SLS), belongs to sulfate salt and has a molecular weight of 288.38. It is a white or light yellow crystal, and is easily soluble in water. Sodium dodecyl sulfonate (abbreviated as SDS) belongs to sulfonate, has a molecular weight of 272.38, and differs with the structure of sodium dodecyl sulfate in that it lacks one oxygen atom and the carbon atom is directly connected to the sulfur atom. Please note the difference so as to avoid misuse. |
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Utilization limitation |
(FDA, §172.822, 2000, mg/kg): dry protein 1000; frozen protein 125; liquid protein 125; marshmallow foaming agent used in an amount of 0.5% gelatin; as a surfactant for solid drinks acidified with fumaric acid and juice drinks acidified with fumaric acid, 25; as moisturizers for grease, 10 (amount of grease). According to the regulation of (FDA, §172.210, 2000), it can be used as a citrus fruit surface coating agent, and the amount is limited per GMP. |
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Chemical property |
It is a white to pale yellow powder, has a slight special smell, and is easily soluble in water. |
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Application |
Sodium dodecyl sulfate has excellent detergency, emulsification and foaming power, can be used as detergents and textile auxiliaries, and is also used as an anionic surfactant, toothpaste foaming agent, mine fire extinguishing agents, foaming agents for fire extinguishers, emulsion polymerization emulsifiers, emulsifying and dispersing agents for medical use, shampoo and other cosmetic products, wool detergent, detergent for silky class fine fabrics and flotation agent for metal beneficiation.
GB 2760-96 stipulates as processing aids for food industry. It used as foaming agents; emulsifying agents; and anionic surfactants. It is used for cakes, drinks, proteins, fruits, fruit juice, and edible oil, and so on.
It is used as surfactants, detergents, foaming agents, and wetting agents, and so on.
It is used as relatively low-level ion-pairing reagents, and is cheaper than sodium heptanesulfonate and sodium pentanesulfonate when less demanding.
It is used as raw material for modifying materials.
It is used as additives in capillary electrophoresis analysis and is generally used as molar solution.
It is also used in other analysis such as flow column analysis. |
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Production method |
Sulphur trioxide method: the reaction apparatus is a vertical reactor. At 32 °C nitrogen gas is introduced into the reactor through the gas vents at a flow rate of 85.9 L·min-1. At 82.7 kPa lauryl alcohol is introduced at a flow rate of 58 g·min-1. The liquid sulfur trioxide is fed into flash evaporator at 124.1 kPa, the flash temperature is maintained at 100 °C, and sulfur trioxide flow rate is controlled to be 0.907 2 kg·h-1. Sulfated product is then rapidly quenched to 50 °C, injected into the aging device and left for 10 to 20 min, and finally injected into the neutralization kettle and neutralized with a base. The neutralizing temperature is controlled at 50 °C. The material is discharged when the pH value is adjusted to 7 to 8.5, to obtain a liquid product which is spray dried to give a solid product.
Batch method: lauryl alcohol is charged into reaction kettle and pre-heated to 30 °C. Then chlorosulfonic acid 0.03 mol in excess than the theoretical amount is sprayed into the alcohol under high speed agitation. The reaction temperature was controlled at 30 to 35 °C. After the sulfation reaction, it is injected into the neutralization kettle and neutralized with 30% lye to a pH value of 7 to 8.5, and finally bleached with 0.4% (weight) hydrogen peroxide. It is spray dried to give a solid. It can also be formulated into solutions according to quality standard.
Continuous method: the reaction apparatus is tubular reactor. Lauryl alcohol is initially saturated with hydrogen chloride. Lauryl alcohol at a flow rate of 334 g·min-1 and hydrogen chloride at a flow rate of 40.5 g·min-1 are fed into saturation chamber through gauge. Then the solution of lauryl alcohol with hydrogen chloride is fed into reactor at 21.4 °C to react with chlorosulfonic acid. After the reaction is subjected to gas-liquid separation, the sulfated product flows from the bottom of the separator into neutralization kettle. It is neutralized with 30% sodium hydroxide at 50 °C to give a liquid product, which is spray dried to give a solid product. |
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Chemical Properties |
White crystalline flakes |
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Usage |
Anionic detergent |
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Usage |
hydrophilic tablet lubricant |
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General Description |
White to pale yellow paste or liquid with a mild odor. Sinks and mixes with water. |
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Air & Water Reactions |
Insoluble in water. |
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Reactivity Profile |
DODECYL SULFATE is incompatible with strong oxidizers. Sodium dodecyl sulfate is also incompatible with cationic materials and with acids with pH below 2.5. Salts, basic, such as DODECYL SULFATE, are generally soluble in water. The resulting solutions contain moderate concentrations of hydroxide ions and have pH's greater than 7.0. They react as bases to neutralize acids. These neutralizations generate heat, but less or far less than is generated by neutralization of the bases in reactivity group 10 (Bases) and the neutralization of amines. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible. |
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Health Hazard |
Inhalation of dust causes sneezing and coughing. Ingestion of large amounts causes irritation of stomach. Dust irritates eyes and may cause burns on prolonged contact. Contact with skin causes some irritation; continued exposure to water solution causes drying out and cracking. |
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Fire Hazard |
Flash point data for Sodium dodecyl sulfate are not available; however, Sodium dodecyl sulfate is probably combustible. |
China (Mainland)
