[mesh1]

The rxn between KI and AgNO3 (or PbNO3) will form an insoluble precip but it is very costly, does anybody know of any other reactions that will enable me to remove the KI from solution?
PS i am talking about an industrial scale. The volume of solution is 1000L.

[Arkcon]

Hmmm ... well, a mod may want to move this to the Engineering sub-board, if your scale is really large.  'Tho 1000 L doesn't seem to be really industrial scale to me, more bench top pilot plant, instead.  What else is in solution?  Are you trying to reclaim iodine, or just get rid of it?

[mesh1]

I work in the chemical waste industry and acetone and water can be added to other solvents to make up a solvent waste stream of upto 27000L which can then be sent to incinerators for waste to energy recovery.
I am trying to remove the iodine content as this adds costs to its disposal as incinerators charge for halogen content.

[Borek]

I am trying to remove the iodine content as this adds costs to its disposal as incinerators charge for halogen content.

And you think you will be able to remove iodine cheaper than they do?

Cu²⁺ may work as well, although I doub't it will be cheaper.

How large is iodine concentration?

[Arkcon]

Hmmm... iodide ion remediation, ay?  Tricky.  I'm guessing, like Borek: said, that any transition metal iodide is insoluble.  I could be wrong.  But if you add it in excess, haven't you made heavy metal soup?  That doesn't help disposal costs.

Chlorine gas will also oxidize iodide ion to iodine.  But how will you get rid of the resulting I2?  Solvent extract?  That won't be cheap.  And incinerators charge for halogen content?  So potassium or even sodium chlorides carry the same charge, as well?  Humph.  That's dumb of them.

OK, so maybe an anion exchange column, to remove all charged ions?  But will they take the cost off, depending on what anion gets exchanged?  And what's that column going to cost you?

Maybe, if you have the authority, you'll look into solvent reclamation, to deal with your waste, and generate some money, or maybe not, hard for me to say.

A little googling leads me to some papers on bioremediation of iodide, which may be useful for you.

[ARGOS++]

Dear mesh1;

How about a stupid idea?:
Use as less as possible chlorine to oxidise the iodide to iodine and then filter the solution with just a sufficient amount of charcoal? Of course I don’t know how it will be effected/influenced by other products in solution (- but maybe as the last step).

Good Luck!
                    ARGOS⁺⁺

[Borek]

I'm guessing, like Borek: said, that any transition metal iodide is insoluble.

No, copper is a special case.

2Cu²⁺ + 4I^- -> 2CuI + I₂

CuI is solid, iodine will be probably easier to separate than I^-.

[mesh1]

The incinerators we send our solvent streams to are restricted by the environment agency with regard to incineration of halogens.
We will blend 6000L of gas condensate with say 5000 litres of aqueous low CV waste (the price of the solvent stream varies with CV. Below 6000Kcal the price is £50 a ton with a £5 surcharge if the halogen conent is too high. Above 6000Kcal the price is £20 a ton and above 8000Kcal the waste is sent free of charge. However, we could just send the gas condensate for FOC however the aqueous waste which lowers the CV of the overall mixture will usually cost over £150 per ton to get rid of hence the blending with the condi reduces the cost massively, especially if we can achieve the £20 a ton rate.
This is where the acetone/water contaminated with KI comes in. Acetone and water has a fairly low CV and is priced at over £60 a ton. If we can blend this in with the solvent stream for £20 a ton without the restrictions of its halogen content then a killing can be made.
With regard to the transition metal soup, this can be disposed of with the money made on the solvent stream with a profit made to the site. I have outlets who will take the transition metal complexes.
Also a column large enough for this operation would not be viable with our current budget unfortunatly.
If I could add a compound to the mixture which would result in an insoluble complex that could be seprated from the solvent my life would be a lot easier! So please any more suggestions are welcomed with open arms!
Cheers for the help so far guys, I will become an active member of this site after the interest you guys have shown in my thread.

[DrCMS]

If I'm reading this right you have 3 waste steams you want to get rid of

1 "gas condensate" - solvent waste with a high calorific value
2 water/solvent mixture
3 acetone/water mixture with KI

Why don't you distil out the solvent from streams 2 and 3 which when mixed with 1 would give you a waste steam that you could sell for say £50-60/T.

The aqueous waste left as long as it does not contain flamable solvents would likely cost less than £50/T to dispose of.

[mesh1]

Dear mesh1;

How about a stupid idea?:
Use as less as possible chlorine to oxidise the iodide to iodine and then filter the solution with just a sufficient amount of charcoal? Of course I don’t know how it will be effected/influenced by other products in solution (- but maybe as the last step).

Good Luck!
                    ARGOS⁺⁺

This is a good alternative The questions I have to ask are a) how much will the chlorine cost and can I on site provide a well ventilated area to conduct the operation and b) costs of both chlorine and charcoal compared to the financial gain of removing the iodine.
Cheers for that suggestion though! Will have a think.

[mesh1]

If I'm reading this right you have 3 waste steams you want to get rid of

1 "gas condensate" - solvent waste with a high calorific value
2 water/solvent mixture
3 acetone/water mixture with KI

Why don't you distil out the solvent from streams 2 and 3 which when mixed with 1 would give you a waste steam that you could sell for say £50-60/T.

The aqueous waste left as long as it does not contain flamable solvents would likely cost less than £50/T to dispose of.

The way we work is we sell a service to customers for removal of their solvent. We then process the solvent to send it out for a cheaper price. Unfortunatly we dont have the facilities to distil the solvent. The aqueous waste we blend with the solvent has some CV as it can sometimes contain phenols etc. However if we blend the aqueous waste with the high CV solvent we can lose it for £20 aslong as the overall CV is higher 6000KcaL.
I just need an alternative reaction to using heavy metal nitrates to remove the KI. I am beginning to think there is no practical solution, but suggestions from you guys are giving me a lot to think about so I am very grateful.