What Have You Bought Today?

t6blo said:
Paid £21 for this exact same thing from Amazon last week :rolleyes:

Carlube Adblue.


£16.99 in Aldi this morning.

Does Adblue have a shelf life or could I stock up now for 3500 miles time ?

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On offer at Costco until the 5th (for members); Redex (Holt) AdBlue £7.18 / 5 litres.

Couldn't see a date on the container though.
 
I wonder what part of the chemical composition degrades in 2-2.5 years? Its mainly water with urea.

[goes off to read up] - disclaimer I'm an electronic engineers not a chemist.

So it appears that urea is the problematic substance here. It is used to produce/absorbe nitrogen (depending on sources I read). Urea forms cyanate when mixed with impure water, hence the ion free water in Ad Blue. Ion free water can be bought in supermarkets to go into steam irons, if you wondered. Over time the urea forms cyanate which isn't dangerous below 50% but can be an irritant. Once opened the solution (AdBlue - ion free water and urea) can mix with non ion free water in the air, and then start to form cyanate. It is recommended that Urea be stored at 4 degrees C, so in the garage is fine. Cyanate may decompose to emit toxic nitric oxide and cyanide fumes when heated to high temperatures.
That'll be why they have a use by date. I can't imagine leaving Ad Blue beyond the expiry date is VERY harmful, but if everyone did then over time it might prove harmful. But in comparison to diesel fumes, if your AdBlue has passed it's use by date, I would not personally worry, i.e. don't pour it away. Instead just use it up before using AdBlue with a longer expiry date.

Every day is a school day.
 
Chemist here. The urea reacts with various nitrogen oxides (NO, NO2, hence NOx) reducing them to nitrogen (N2), and also yielding water and CO2 (tiny amount of CO2 compared to the regular exhaust). This takes out the harmful NOx, which is the source of that yellow smoggy look over cites at sunset.

Yes, the urea decomposes to cyanate ions, which further decomposes to ammonia and CO2. Lots more chemistry in that which excites the inorganic chemists, but as there are no hydrocarbons involved it’s not my area.
 
drinfinity said:
Chemist here. The urea reacts with various nitrogen oxides (NO, NO2, hence NOx) reducing them to nitrogen (N2), and also yielding water and CO2 (tiny amount of CO2 compared to the regular exhaust). This takes out the harmful NOx, which is the source of that yellow smoggy look over cites at sunset.

Yes, the urea decomposes to cyanate ions, which further decomposes to ammonia and CO2. Lots more chemistry in that which excites the inorganic chemists, but as there are no hydrocarbons involved it’s not my area.
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Thanks Doc! I knew there would be someone with a more relevant qualification.

I was attempting to address the comments on it's use by date, and wondering what the consequences of leaving it to degrade would be.

But it appears everything has a sell by or use by date. We help a local food bank by collecting out of date food from a local supermarket. They gave us a few dozen bottles of water recently... I mean does water go out of date???
 
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