Homemade Soap and chemistry
1) What is soap?
There seems to be a recipe of soap more than 5000 years ago. There is a legend that made soap made by chance from ashes and water of fat and tree when flesh of sheep was baked, to complete as a recipe.
1-1) History
In Europe, especially France and Mediterranean side produced by olive oil, the culture of making soap was continued until the 18th century. It has been mainly used for washing clothes and so on.
Characteristics of age soap
Originated in Babylonia (Syria) 2800 BC A mixture of ash and fat
From 9th to 10th century to Spain, Italy Soft soap of charcoal, tallow
12 th century Marseille soap seaweed ash and olive oil
Industrialization of alkaline agents in the 18th century Soda carbonate and fats and oils
Electrolysis method of modern caustic soda method of caking of fat and caustic soda
Ion exchange membrane method of modern caustic soda neutralization method of fatty acid and caustic soda
1-2) History in Japan
In Japan, there was a culture of "Yuami" from before the Warring States Period, washing the body with hot water. At that time, soap was not used. It was transmitted from Europe and was presented to Daimyo, but ordinary people were washing their body with pumice.
1-3) Synthetic soap
A large amount of soap used by soldiers will be needed during the First World War, but as a result of the development of the coal chemical industry in Germany, a synthetic detergent was invented, not enough for natural materials.
1-4) straight chain alkyl
Synthetic detergents containing branched alkyl fats and oils which are difficult to be biodegraded pose a problem and have been improved to straight chain alkyl fats and oils which are easily biodegradable.
1-5) Phosphorus-free
Detergents containing phosphorus caused eutrophication and sludge and red tide. Phosphorus is the nutrition of the plant, but when it flows excessively into the river, a phenomenon occurs in which plankton breeds abnormally and the fish can not live. Therefore, phosphorus-free phosphorus-free detergent was developed. (Top released in 1979)
1-6) Enzyme detergent
Among the improvements in detergents, soaps containing enzymes that break down protein contamination have been released, focusing on the fact that the soil of clothes is protein. Even now, it is becoming mainstream detergent. After that, as the synthetic detergent became more compact, we were able to do the same amount of washing with a small amount.
2) Environment and Chemicals
Household wastewater exceeds industrial and agricultural wastewater. Phosphorus is proceeding with countermeasures such as phosphorus-free detergent. On an industrial scale, recycling is proceeding to recover wastewater and harmful components after detoxification and not to discharge it to the outside. In agriculture, wastewater is the cause of water pollution due to the use of nitrogen, potassium, phosphorus fertilizer and the use of pesticides.
Regarding domestic wastewater, which is the party we are the most from things from the kitchen, followed by soul, bath and laundry. Among them, dirt by disposing and cleaning the food itself is conspicuous. Do not leave it, do not drain easily into water, when washing dishes, you can devise to wipe off dirt and start washing.
The soiling of detergents is estimated at about 12%. It is important that this is not too much detergent. It is to protect the appropriate amount to use against water. Among detergents, we can lower the burden on the environment by paying attention to ingredients. Soap made from grease is made of fatty acid (a kind of carboxylic acid) as a material. On the contrary, many synthetic detergents use sulfonic acid as a material. Sulfonic acid is neutral detergent and is gentle to the skin, but it is said that the load on the environment is high.
2-1) sulfonic acid
The main applications of linear alkylbenzenesulfonic acid are about 80% home laundry detergent, less than 20% cleaning as industrial washing, kitchen and vehicle washing, and it is rarely used for household kitchen detergent It is gone.
Sulfonic acid is a type of acid that is synthesized using sulfuric acid. Because strong acid such as sulfuric acid and strong alkali such as caustic sword are reacting, it does not become alkaline and becomes neutral. We do not make soap scum even in hard water.
Carboxylic acid is derived from normal fats and oils. Fatty acids are a type of carboxylic acid that when reacted with strong alkali can produce alkaline soap.
3) handmade soap
3-1) Material of soap
Soap materials are oil, caustic soda and water. Caustic soda is representative of strong alkali.
Caustic soda is a chemical that is intensely irritating to the skin and mucous membranes, so be careful as it will blind you in your eyes. If it gets in your eyes rinse with plenty of water, it will take the ophthalmologist immediately.
3-2) What is 鹼 化
Reaction that fat and caustic soda reacts to make soap is called crispy. Glycerin is also produced as soap and byproduct.
The amount of soap increases with time. However, it will slowly proceed until a certain period of time, suddenly becoming brittle and solidify. Normally, the viscosity rises in about 1 hour and it solidifies in about 24 hours. And at the end the reaction slowly ends. In addition, it is necessary to neutralize caustic soda with carbon dioxide gas in the air, so it is usually necessary for aging with handmade soap for one or two months.
4) Alkali
4-1) Acid and alkali
Among the properties of water, those with a sour taste are called acids. Citric acid such as apple and lemon is representative. Apart from organic acids, there are gastric juice, hydrochloric acid, sulfuric acid and so on. They found that those with high hydrogen concentration in water recognized the tongue as sour. Therefore, acid is supposed to increase the hydrogen concentration of water.
Alkaline is a null nulled product such as ash which cancels the action of acid. It acts to lower the concentration of oxygen.
The value obtained by measuring acid / alkali with hydrogen concentration is called pH. The pH = 7 is neutral water. A state with very little hydrogen (concentration of -14) is called pH 14. There is a difference of 10 times the hydrogen concentration when the pH is 1 different.
4-2) Water polarity
The reason why oil and water do not mix is because water has polarity. Polarity is related to the fact that molecules of water are electrically biased. Fats and oils are not mixed with water because there is no electric bias. On the other hand, molecules with large electric bias are easily soluble in water. Mainly metal cations and anions that bind them are dissolved in water.
4-2) Sodium hydroxide
Sodium hydroxide is representative of alkali.
Caustic soda melts very much in water. It can be seen that it dissolves more than three times even when compared with similar sodium salt salt, baking soda, etc. This is the polarity strength of sodium hydroxide.
Although sodium bicarbonate is alkaline, it is weak in polarity and hardly soluble in water, so it can not be used for making soap. Sodium salt is polar and soluble in water, but because it is neutral, soap can not be made.
Caustic soda, sodium bicarbonate, salt can be a material to synthesize each other. Industrially, caustic soda is made by electrolyzing salt water.
4-3) pH and color
Many plant dyes change color due to acid alkali change. Anthocyanins, which are representative of plant pigments, are included in red cabbage and hibiscus. Anthocyanin is red when it is acidic, and it changes color from blue to alkaline, and it is used as an indicator to measure pH by using it.
"Red milk" also known as reddish is also discolored a little by alkali. The red soap is an unnatural color. Generally, vivid colors of anthocyanins are discolored on the alkaline side. It can be said that the characteristics of such color are the result of reaction of the dye to pH.
4-4) color
The color is the wavelength of light. It is the length of light wave. The arrangement of the rainbows is arranged in order of the length of the wavelength of the light.
The complementary color of the absorbed light is visible.
Dye changes light absorbed by chemical reaction. The color that can be seen also changes accordingly.
5-1) Sedimentation value
The amount of caustic soda, which is an alkali necessary for sanitization, is organized into recipes and so on as suffering value.
Sulfurization value can be obtained experimentally, but it is calculated from the average molecular weight (ie carbon length).
It is the amount of alkali necessary for saponification where 100% reaction per unit weight of fats and oils progresses. Since oils and fats are mixtures of various fatty acids, their digestibility is different for each fat depending on the mixing ratio. There are values when using potassium as alkali and the value converted into sodium. The potassium digestibility value of olive oil is 191, and 40/56 is 136 in sodium digestion value. It may be written as 0.136 per gram value.
5-2) iodine value
A value obtained by arranging the properties of oils and fats by the amount of iodine reacting to oils and fats.
Among fats and oils, even with the same number of carbons, it can be classified without the presence of double bonds in the carbon skeleton.
Carbon = carbon double bond (unsaturated bond) is highly reactive, it is oxidized and easily deteriorated.
The one with many C = C bonds contained in the oil is consistent with high iodine content.
Something without double bond is called saturation.
One having one double bond is called unsaturated,
Those with two or more double ties are called polyunsaturated.
Iodine value is also an index connecting molecular structure and shape (smooth / solid).
Reaction rate when using this as soap is fast: medium: slow
In other words, an oil containing a lot of unsaturated animal solid fat is low in iodine value and has a principle of accelerating crowding reaction.
6) Health and fat
6-1) Trans fatty acid
There are two different types of molecules among unsaturated fatty acids containing double bonds. It is named Sys · Trance. Cis is in the form of a molecule bent with double bonds, with a carbon skeleton on the same side of the double bond. This is the form of the molecule contained in the natural vegetable oil. Because of this bending it is difficult for molecules to gather, it does not become a solid, it becomes a liquid oil.
Margarine · shortening adds hydrogen to harden liquid vegetable oil. At that time, a transformer type will be formed in the double bond.
Trans fatty acids are unsaturated fatty acids but differ from the double bonds of natural plants. The risk of cerebral infarction is suspected and intake should be modest.
We also try to eat well-balanced polyunsaturated fatty acids with good balance.
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