Bottle of bleach
Some chemicals, through Oxidation Reaction to Bleach Goods function, while the number of itemsBleachThat is it Color Remove or pale. Commonly used chemical bleaching agent is usually divided into two categories: chlorine bleach and oxygen bleaching agent. Chlorine containing bleaching agents Sodium hypochlorite , and oxygen bleaching agent containing Hydrogen peroxide Or will release Peroxide The Chemical compound For example Sodium perborate Or Sodium percarbonate . Bleaching powder The composition is usually Calcium hypochlorite . Bleaching is Staining The initial steps in the process of.
Bleaching agentsIn addition can improve food color
Food bleaching agent
Outside, also has antibacterial and other effects, a very wide application in food processing. Oxidative bleaching agent as well as flour treatment agent of benzoyl peroxide and a few varieties, little practical application. As for hydrogen peroxide, permitting only in certain areas for students Milk Fresh, bagged Bean curd Dry, use no oxidation bleaching agent for.
Bleach is the consumption of food and oxygen through the reduction in chemical reaction, damage, inhibition of food enzymes Activity And food coloring, make food Browning Pigment Fade or from browning, but also has a certain antiseptic effects. China Allows the use of bleaching agent Sulfur dioxide , sodium sulfite, sulfur and other 7 kinds of sulfur, which only Candied fruit , Dry Fruits , Dried vegetable , Fans , Sugar Fumigation.
The general 84 disinfectant The main components of NaCl and NaCLO to generate HClO with strong through the slow reaction Oxidation And bleaching.
Bleach into oxidized and reduced, oxidized and divided into salinomycin (chlorine) and acid (oxygen) class. Salinomycin force strong bleaching agent, Sterilization , deodorization effect is good, suitable for use in bleaching clothes, is not available for fancy clothes. Not every kind of cloth can be
The use of salt in bleach, so be sure to read the instructions. In addition, if containing acid element Washing powder To use words, will reduce the effectiveness of washing powder, so do not use. Acid bleaching stress agent mild color clothes, can feel at ease to use, is used for silk and Wool No problem. If the washing machine and washing powder together, to prevent Macular And Black spot Very effective. Reducing the strongest type of bleaching agent, as long as the white fiber can be used, but can not be used for fancy clothes. Salt pigment bleaching macular agent wash off, Blood And The soil So stubborn dirt, use the absolute effective. General should contain hypochlorous acid, but also of course with hydrogen peroxide, Ozone To bleach, and even uses sulfur, different materials are also different, usually with the bleaching agent is mainly calcium hypochlorite (Ca (ClO) 2) in general, the main component is sodium hypochlorite bleaching agent sales, sodium hypochlorite hydrolysis to produce hypochlorite, sodium hypochlorite has strong oxidation, oxidation coloring. As well as Hydrogen peroxide solution , bleaching powder is used to bleach oxide pigment. May contain sodium thiosulfate objects with reduction bleaching bleaching agent, sodium thiosulfate reducibility.
The HgCl2+2NaCl → Na2HgCl4 (absorption liquid
Dental bleaching agent
The Na2HgCl4+SO2+H2O → HgCl2SO3]2-+2H++2NaCl
HgCl2SO3]2-+HCHO, HgCl2+HOCH2, SO3H
3HOCH2SO3H+ acid bleaching Parafuchsin, poly (methyl sulfonic acid rose red violet red complex)
The absorption liquid and with mercuric chloride Sodium chloride Function generation Four Mercury sodium chloride , when Sample In the SO2 and the absorption liquid, to form a stable complex (can prevent the loss of SO2), the complex with formaldehyde and hydrochloric acid violet red complex formation, color depth and proportional to SO2 concentration, the 580nm colorimetric assay.
Household bleach or sodium hypochlorite NaClO at home to be used as a bleaching clothes, remove stains and disinfection. This is because the sodium hypochlorite can produce chlorine free radicals -- is a kind of can be with many substances oxidation reaction.
Bleach hair containing H2O2 (hydrogen peroxide), when it decomposes will release oxygen free radicals. Oxygen and chlorine radicals has bleaching effect the same.
Chlorine bleach is usually used in conjunction with the washing powder, housewives will also use it as a disinfectant. Should pay attention to, do not bleach and detergent containing ammonia mixed together, also do not use chlorine bleach to clean urine stains, because it will produce three nitrogen chloride chlorine ammonia poisonous and explosive. And don't bleach and toilet cleaning agent are mixed, because it will produce toxic chlorine gas.
But not all characteristics of bleaching agent has oxidation. For example, some sulfur dioxide bleach formula will join the low sodium sulfite Na2S2O4 and bleached flour, dried apricots, alcoholic drinks or fruit is a strong reducing agent.
Another kind of bleach, chlorine dioxide is used in the bleaching of wood pulp, fats and oils, cellulose, flour, textile, beeswax and other industrial.
In the food industry, some organic peroxides (acetone peroxide, benzoyl peroxide etc.) and other chemicals (such as bromate) will be used for flour bleaching agent and accelerant.
1, water soluble solid samples
Various Can Samples were crushed) uniform like 10g, with a small amount of water dissolved after transfer to a 100ml volumetric flask, add 0.5NNaOH4ml → 0.5NH2SO44ml → Na2HgCl420ml → add up to a constant volume 100ml, filter backup 2) Starch Processing category samples ( Vermicelli , Vermicelli Etc.) weighing crushing even like 10g, a small amount of water dissolved transferred into 100ml volumetric flask, add Na2HgCl420ml to soak for 4 hours (if the liquid does not clarify, to join the Potassium ferrocyanide And zinc acetate solution 2.5ml), water volume, filter backup 3) liquid sample processing draw sample liquid 10ml → 100ml → Na2HgCl420ml → volumetric flask with constant volume, filter backup.
2, draw the standard curve
25ml colorimetric tube 123456
SO2 standard 2 μ g/ml0.01.02.03.04.05.0ml
1ml0.2- type 1ml
The chromogenic agent 1ml
Constant volume, standing for 15 minutes, to 580nm Determination To draw the standard curve.
3, the sample analysis
Suction filtration of 5ml → colorimetric tube, and the absorption liquid 5ml, plus 0.2- Formaldehyde The 1ml → 1ml → chromogenic agent Mixing → constant volume and set aside for 15 minutes, in the determination of 580nm, check the appropriate SO2 content from the standard curve based on samples of wavelength
Sample → H+ → ventilation (acidification Air And Chlorine ), heating, double condenser tube (can exclude the interference of organic acid and volatile acid) → SO2 → H2O2 → H2SO3 → by absorption liquid oxidation → H2SO3 → (1) and (2) determination; Gravimetric method for the determination of.
Samples, acidification, distillation → SO2 → H2O2 → H2SO3 → by absorption liquid oxidation → H2SO3 → (1) neutralization test; (2) weight method
The Japanese use double condenser tube can be excluded Organic acid And volatile matter of interference, some scientific research units, are also useful for ventilation method to measure SO2, but relatively simple, mainly some volatile gas and organic matter are all here, interference, can not be ruled out the error is large, so the determination of residues of SO2 colorimetric method, and the USA The acidification distillation neutralization test SO2, and neutralization titration on the handout.
Principle: sulfite heating under acidic condition, evaporation of sulfur dioxide, and then by the hydrogen peroxide solution absorption and oxidized into sulfuric acid, and then the aqueous alkali titrate to the endpoint olive, then according to the consumption of alkali Calculation Out Sample Determination of the content of SO2. Why not using neutralization titration method as National standard , instead of using the colorimetric method for the GB, toxicity and colorimetry in four mercury sodium chloride and, this is mainly because the neutralization test of SO2 in sample treatment is more trouble, but also to pass into the N2, harsh conditions, so using the colorimetric method for the determination of SO2, and the Accuracy Also higher.
In the production of food, in order to make food.
Barreled bleaching agent
A unique color, often adding bleaching agent, depending on the oxidation or reduction of its ability to inhibit discoloration, damage factor of food, so that food faded or from browning. In general Food In the process of bleaching agent in addition to the requirements of the food color have a certain effect, quality, nutritional value of food and The preservation period There shall be no adverse changes. Bleaching agent from the mechanism is divided into two categories: (1) reduced (SO2, sodium sulfite, Sodium Bisulfite, Sodium metabisulfite And so on); (2) oxidized (H2O2, hypochlorous acid etc..
Method for determination of reduced bleaching agent with pararosaniline hydrochloride colorimetric method (GB); (2) titration ( Neutralization Method); (3) the iodometric method; (4) polarography; (5) High performance liquid chromatography Method for determination of oxidized bleaching agent are: (1) titration; (2) quantitative colorimetry; (3) high performance liquid chromatography; (4) use polarography to bleach, single use, can also be mixed use. With the expansion of international trade, foreign food continue to enter the Chinese market, Japan In recent years, is a mixed bleach, its ingredients are 70- sodium hyponitrite, Sodium Bisulfite 14-, anhydrous Jiao Linsuan 3-, sodium phosphate, sodium hexametaphosphate 8- 3- 2-, anhydrous sodium carbonate. This mixture of bleaching agent than either single bleaching effect is stable, while preventing the food discoloration and fading. Chinese national standard: Biscuits Sugar, vermicelli, vermicelli, the residual SO2 content shall not exceed 50mg/ kg; Canned mushroom , Bamboo shoots , Wine Shall not exceed 25mg/ kg. SO2 itself has no nutritional value of food, not the indispensable ingredient, if the amount is too large, the health of the human body will bring certain impact. When the solution is 0.5-1-, which produce Toxicity , a corrosive action on the one hand, on the other hand, the destruction of the blood coagulation and generate heme, finally The nervous system Occurrence of paralysis. A, acid bleaching pararosaniline colorimetric method of Fuchsine Colorimetry (pararosaniline hydrochloride colorimetry) colorimetry at home with the more, this method is the key to the sample SO2 is extracted, the commonly used four mercury sodium chloride extraction liquid (mainly in the analysis in order to avoid the loss of SO2, often Na2HgCl4 as absorption liquid).
The bleaching agent can improve food Color and lustre Outside, also has antibacterial and other effects, a very wide application in food processing. Oxidative bleaching agent except as Flour Treatment agent Benzoyl peroxide , Chlorine dioxide A few species, little practical application. As for hydrogen peroxide, our country only licensed for raw milk preservation bags of dried bean curd, in some areas, agents use not oxidative bleaching as.
Bleach is through reduction chemical processes in food Oxygen , damage, inhibition of enzyme activity and food coloring, make food browning pigment faded or from browning, but also has a certain antiseptic effects.
China allows the use of bleaching agent Sulfur dioxide , Sodium sulfite , Sulfur , Chlorine dioxide 7, the sulfur, dried fruits, dried vegetables only preserves, fans, sugar fumigation, and limit the use amount of clear.
Bleach is destroyed, the hair color of factors inhibiting food, make it fade or make food from browning material, oxidation bleaching and bleaching two.
The 1, the reaction temperature was 20-25 ℃, low temperature and low sensitivity, so the standard series of pipe and the sample at the same temperature color; 2, reaction temperature if 15-16 ℃, holding time should be extended to 20 minutes;
3, pararosaniline hydrochloride in hydrochloric acid has an effect on the color, add Hydrochloric acid The amount, color shallow; dosage is less, the color is deep, so the reagent must by operation;
4, the concentration of formaldehyde in 0.15-0.25-, Color Stable, so choose 0.2- Formaldehyde Solution;
5, the determination of darker samples, available 10- Activated carbon Decolorization;
6, the sample with Na2HgCl4 absorption liquid in a volumetric flask of 100ml water to scale, shake up, this solution is very stable in 24 hours at 4 ℃, otherwise can be used for a week;
7, the SO2 measured by HgCl2 toxicity is very strong, so the experiment should be Caution. Science and technology reported using EDTA ( EDTA ) reagents instead of Four Mercury sodium chloride, but this experiment did not confirm.
In 2013 May, Guangxi, a media buying The Chinese people , Colgate , The two girls Six brands such as whitening Toothpaste , and professional The detection mechanism After testing, found brand of whitening toothpaste were more or less containing bleaching agent composition, and concluded that this material is a kind of bleaching Sulfite Or a similar substance. China oral care industry association in May 3, 2013 that the
, Dilute sulfuric acid And Starch Do the test agent, test method of whitening toothpaste ingredients, from the scientific principle is greater uncertainty, many factors and material can change the color of the solution. According to the association, reported by the media whitening toothpaste containing sulfites, and the fact that out there.