I would like to ask why urea behaves in this way
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When doing the experiment, I bought a bag of urea; I don’t know why it turned red, and it also formed severe lumps. What’s the reason for this? Also, in what solution does urea turn red?
You bought low-quality urea; if you purchase genuine urea from state-owned enterprises, there will be no problems.
Reply to 2# Xishui: If the iron content in the final urea product is >36 ppm, it will turn red.
For experiments, urea of analytical purity is generally used; so this problem shouldn’t arise. The reddening of urea is mainly due to an excessive level of nickel in it, and clumping is quite normal. This occurs primarily when the concentration of the urea solution is too low during the production and granulation process, or when the speed of the nozzles isn’t properly controlled. I’m also a beginner, so there are some things I’m not entirely sure about
Didn’t it come in red when the original poster bought it?????????????
The system turns red when the nickel content due to corrosion exceeds the limit (of course, the red color is mainly caused by iron ions). I wonder whether the original poster’s item turned red right after purchase or only during testing?
When I opened them after buying them, some of them turned red and formed clumps; what I bought was that kind of urea used for fertilizing crops. Analytically pure urea was not used.
Reply to 6# fjhuyuyang: When I bought it, I didn’t know whether it had turned red or not. After leaving it there for some time, we needed to conduct an experiment, so I went over and opened the bag – some parts of it had indeed turned red! That's it.
The urea purchased by the poster is of poor quality; an excessive Ni content causes the color to turn red. Clumping occurs because it wasn’t stored properly; urea clumps together when it absorbs moisture!
Reply to 1# Vieff: 1) Urea caking: This indicates that the humidity in the air where the urea is stored is relatively high (provided it was not caked when purchased and the packaging has been opened). 2) Urea turns red: It is estimated that the urea itself is of substandard quality, with a high content of iron ions; the common cause is corrosion of the equipment caused by sulfur ions present in the system.
Urea caking: Indicates that the moisture content in the urea is relatively high； Urea appears red: it contains a high level of iron and nickel ions ；