What is oxygen consumption? Why is it an important indicator in down inspection and testing

2023/01/10

2020-03-16

In the quality assessment of down products, the key indicators include down filling, down content, down content, bulkiness, oxygen consumption, residual fat rate, cleanliness and odor. The indicators of down filling, down content, down content and bulkiness determine the effect of keeping warm; while oxygen consumption, residual fat rate and cleanliness are indicators of human health and safety, and those that do not meet the standards Products may cause consumers to develop respiratory diseases such as allergies and asthma.
 
Most of these indicators can be understood literally, but the word "oxygen consumption" is really confusing.

In this regard, some readers have mentioned it in the messages of Feather Gold Network, so the editor has compiled some information for your reference, and I hope to get corrections from experts.

 

Why Test Oxygen Consumption

Down is a by-product of goose and duck farming. It is often contaminated with blood, tissue fluid, feces and other dirt during the process of obtaining it. The processing factory purchases these hairs from the slaughterhouse, and after a series of processes such as hair separation, washing, drying, disinfection and dust removal, it can extract high-quality and clean down raw materials, which are sold to down products companies to produce various products.

 
If the washing process is insufficient or the down storage is improper, the down will deteriorate, and even more reducing organic and inorganic impurities remain on the surface. Reducing substances have strong chemical activity, which can provide nutrients for the reproduction and growth of microorganisms, and eventually cause down fiber damage and quality degradation.
 
GB/T 14272-2011 "Down Clothing" stipulates that when the oxygen consumption is not greater than 10mg/100g, the microbial indicators of down and feathers do not need to be tested; when the oxygen consumption is greater than 10mg/100g, the down and feathers need to be tested Microbial indicators.

 

Oxygen consumption is related to water quality testing
Oxygen consumption is also known as permanganate index, also known as potassium permanganate consumption. As early as the 1950s, Japan included oxygen consumption in the water quality standards for drinking water. 2001 In June, my country's Ministry of Health also included oxygen consumption in the "Hygienic Standards for Drinking Water".

 
In fact, oxygen consumption can reflect the degree of pollution of oil, protein, humic acid, urine and feces to water bodies, and is a comprehensive indicator for evaluating the total amount of organic matter pollution in water quality.
 
The first step in the determination of down oxygen consumption is to create "sewage".

 

▲ Take the sample and place it in a flask, and add distilled water to wet the down

▲ Oscillate with a horizontal oscillator, the number of oscillations is 4500 to 5000 times

 

▲ After shaking, the water was filtered through a standard sieve into a large beaker for later use.

 

Potassium permanganate titration

At present, the detection methods of down oxygen consumption are basically the same at home and abroad.

 

First, take out 100ml of distilled water and 100ml of sample liquid with a measuring cylinder, place them in two Erlenmeyer flasks respectively, and then add 2mL of 3mol/L sulfuric acid to each. (Note: If the acidity is too high, potassium permanganate is easy to decompose, but if the acidity is too low, the reaction speed will be slow, and manganese dioxide will precipitate.

Sulfuric acid is commonly used to adjust the acidity of the solution. Nitric acid is oxidizing and should not be used; hydrochloric acid is reducing and will be oxidized by potassium permanganate and is not suitable for use. )

▲ Two flasks filled with sulfuric acid.

Then in 100mL of distilled water, add a drop of standard potassium permanganate solution of known concentration, as a blank sample for control; while in the filtered water of 100mL test sample, add a standard potassium permanganate solution of the same concentration drop by drop .

At the beginning of the titration, the reaction is slow, and the titration should be slow; as the manganese ions generated by the reaction increase, the reaction speed will be accelerated, and the titration speed can be accelerated accordingly, but still not too fast.

▲ blank sample for control

 

▲ Add the same concentration of standard potassium permanganate solution drop by drop.

Finally, when the filtered water of the sample also shows the same pink color as the blank sample, the oxygen consumption can be calculated by the volume of the consumed potassium permanganate solution.

 

The principle is that potassium permanganate solution has strong oxidizing ability in acidic environment, and its own color (pink), if it reacts with reducing substances, the color will fade, and the filtered water of the sample will not change color; if not Reaction occurs again, that is, oxygen is no longer consumed, and the potassium permanganate solution dissolves in water, turning the filtered water of the sample pink at the same time.

 

The above is the introduction about the oxygen consumption of down. If there are any omissions, readers are welcome to leave a message to supplement.

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