[China Glass Net] Cleaner and its scope of use
The more commonly used cleaning agents are soap, synthetic detergents (such as washing powder), washing liquids (cleaning liquids), organic solvents, and the like.
Soap, synthetic detergents, etc. are generally used for instruments that can be directly brushed with a brush, such as non-metering and non-optical glass equipment such as flasks, beakers, and reagent bottles.
Soap and synthetic detergents can also be used for the washing of measuring glass instruments such as burettes, pipettes, and measuring bottles, but they cannot be brushed with a brush.
The lotion is mostly used for glass instruments that cannot be brushed with a brush, such as burettes, pipettes, measuring bottles, colorimetric tubes, glass fused funnels, Kjeldahl flasks, etc., which are also used for special requirements and shapes. The glass instrument and the brush do not get the dirt off.
Preparation and description of lotion
Method: Weigh the prescribed amount of potassium dichromate, grind it in a dry mortar, add the fine powder to a glass container filled with appropriate amount of water, heat, stir to dissolve, and after cooling, place the glass container In the cold water bath, slowly add concentrated sulfuric acid intermittently, keep stirring, do not make the temperature too high, the color of the container content is gradually deepened, and pay attention to cooling, until the addition is finished, it is obtained.
Description:
(1) Sulfuric acid can produce a strong exothermic reaction when it meets water. Therefore, after the potassium dichromate solution is cooled, the sulfuric acid is slowly added, and the mixture is stirred while being operated, so as not to operate in the opposite direction to prevent explosion.
(2) The cleaning liquid is specially used for cleaning glassware, and the reason why it can decontaminate the pyrogen is that the product has strong oxidation effect. When potassium dichromate meets concentrated sulfuric acid, it produces chromic anhydride with strong oxidation.
(3) The cleaning efficiency of chromic acid depends on the amount of chromic anhydride (CrO3) produced in the reaction and the concentration of sulfuric acid. The more chromic anhydride, the thicker the acid, the better the cleaning efficiency.
(4) Before cleaning the glass instrument with cleaning liquid, it is better to rinse the instrument with water first, wash most of the organic matter, and dry the instrument as much as possible, which can reduce the consumption of cleaning liquid and avoid dilution and reduce efficiency.
(5) This product can be reused, but the solution has lost its oxidation effect when it is green. It can not be reused, but it can be reused.
Renewal method: take the waste liquid to filter out the impurities, and slowly add potassium permanganate powder with stirring, about 6-8 g per liter, until the reaction is completed, the solution is brown. The precipitate is allowed to stand, the supernatant is decanted, and heated at 160 ° C or lower to evaporate the water to obtain a thick brown-black liquid, which is allowed to cool, and then an appropriate amount of concentrated sulfuric acid is added, and the mixture is mixed to dissolve the precipitated potassium dichromate. spare.
(6) Sulfuric acid is corrosive and should be handled carefully.
(7) Washing the instrument with chromic acid cleaning solution is to use the chemical reaction with the dirt to wash away the dirt, so it should be soaked for a certain period of time, usually placed overnight (according to the situation); sometimes it can be heated to make A full-fledged opportunity.
Methods and requirements for washing glass instruments
(1) General glass instruments (such as flasks, beakers, etc.): first rinse with tap water, then scrub with soap and washing powder, then wash with tap water, then rinse with purified water 3 times (should be washed along the wall) And fully oscillate to improve the flushing effect).
Measuring glass instruments (such as burettes, pipettes, measuring bottles, etc.): can also be washed with soap and washing powder, but can not be brushed with a brush.
(2) Precision or difficult-to-wash glass instruments (burettes, pipettes, measuring bottles, colorimetric tubes, glass funnels, etc.): rinse with tap water, drain, and then treat with chromic acid cleaning solution for a period of time ( It is usually left overnight, then washed with tap water and then rinsed 3 times with purified water.
(3) When washing the instrument, the hand should first be washed with soap to prevent the oil on the hand from sticking to the instrument wall, which increases the difficulty of washing.
(4) A cleaned glass instrument should not hang water droplets (when the instrument is washed upside down, the water does not hang water after the water flows out).
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