Pickle Disposal

[art925]

I have asked my local council to pick up my old pickle for disposal, however they want me to provide information on the chemical composition of each solution.

I have a number of pots of 3 different solutions from over the years, and many many years since my last chemistry lesson.

I have some vitreol or sulphuric acid based solution, I have citric acid based solution and acetic acid/vinegar with dissolved salt, (although I feel the salt is now crusted). As these all contain copper in solution, what is the chemical composition of each please....

[Dennis]

By being public spirited you've opened a can of worms there Les. Using my school chemistry (1948), I would declare: dilute sulphuric acid with copper sulphate, dilute citric acid with copper citrate and dilute acetic acid with copper acetate, concentrations unknown.
I think only the copper content could be remotely hazardous,and that would colour up your hydrangeas a treat. Citric and acetic acids decompose naturally in soil, and sulphuric acid can be neutralised with lime to form gypsum, which is a treatment for soil heavy with clay. Regards, Dennis.

[art925]

Yes, thanks Denis, this is huge. I live in the middle of nowhere so to speak, and as I have a natural spring in my garden, I am opposed at the potential to contaminate that. We sit just on or below natural water levels which means in essence the water just sits in the land and goes nowhere, so increases copper contamination potential. Here in NL the council look badly on business chemical waste going straight down the drains or into the land.
In place of lime, would bicarb neutralise the acids? ...then yes I still have copper in solution, but the acid is neutralised, meaning less translation for me and I can transport the solution myself to the disposal unit and pay less.

[Dennis]

Hi Les,

Leaving out the copper, the two organic acids ( citric and acetic ) don't really need neutralising as they dissociate into harmless substances in soil, as would for instance rotten fruit. The real way to neutralise sulphuric acid is to render it insoluble using slaked lime (calcium hydroxide),to make calcium sulphate, also known as gypsum, or plaster of Paris. Gypsum is the substance used to treat heavy soils.

Because the reaction could be quite violent, I cannot really advise you how to do it safely yourself. Whatever you do, avoid quicklime, (calcium oxide)which is extremely hazardous.

Dennis.