Disposal of Sodium Thiosulfate?

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Ian
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Disposal of Sodium Thiosulfate?

Post by Ian » 09 Apr 2018, 11:17

Dear "Brains Trust"

In the old (now extinct) CIS Appendix D, the recommended disposal for Sodium Thiosulfate was "down the sink (to the sewer). The new SDS sheet tells me that Sodium Thiosulfate is "Very toxic to aquatic organisms" and to "avoid release to the environment". So, how do people dispose of Sodium Thiosulfate these days?

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Ian

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Re: Disposal of Sodium Thiosulfate?

Post by Labbie » 09 Apr 2018, 11:58

With a lot of water,
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Re: Disposal of Sodium Thiosulfate?

Post by Lyn » 09 Apr 2018, 13:22

Check the ASSIST site. Yes, dilute with lots of water.

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Re: Disposal of Sodium Thiosulfate?

Post by Merilyn1 » 10 Apr 2018, 09:41

I've just posted the specific question to Science Assist as the only guide was in an answer to a prac with sodium thiosulfate and HCl. Is this the one you saw Lyn?
We should use Science Assist more often - if we don't their funding will end.

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Re: Disposal of Sodium Thiosulfate?

Post by Lyn » 10 Apr 2018, 13:08

Yes that is the one I saw and although it was a combination of the two chemicals I thought the answer was relevant to your question. It will be interesting to see what the answer is to your original question. I think that if the solution of sodium thiosulfate is very weak that with further dilution it would be OK. Anyhow I'm not a chemist so we can wait and see what Science Assist has to say.

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Re: Disposal of Sodium Thiosulfate?

Post by Merilyn1 » 10 Apr 2018, 14:55

I'm guessing the answer will be to flush it down the sink, but thought it was a good question to put to them.

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Re: Disposal of Sodium Thiosulfate?

Post by Ian » 11 Apr 2018, 15:57

Thanks all. Yes it was the Hypo Cross reaction, (with the HCl). The Na2S2O3 was only 0.2M, and probably mostly used up in the reaction.
The Science Assist solution seems to be to filter out the precipitated sulfur and bin it, then tip the filtrate down the sink. I will give that a go. Thanks for all your help.
Ian

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Sodium thiosulfate

Post by astagni » 12 Aug 2019, 13:04

I'm confused!! !
Needed to label some more Sodium thiosulfate containers. Prevously to subscribing to Riskassess, I've used Chemwatch. Riskassess says "not classified as hazardous", blue dot etc However Chemwatch lists it with "warning' and ' toxic to aquatic life'. Interested in any comments

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Re: Sodium thiosulfate

Post by Labbie » 12 Aug 2019, 14:04

sodium thiosulfate*
sodium hyposulfite
hypo
7-12
1
2
3
4
5
6
-
NR

Not Hazardous -
-
7772-98-7 Moderately toxic if ingested. Forms toxic gases on contact with acids and on heating. Photographic fixer. Used in crystallisation experiments and redox titrations. Small quantities can be sued for chemical gardens and crystal growth experiments with students Years 5-6.
Disposal: Waste solutions of this chemical may be disposed of down the sink (to sewer).

Q-Stores

15

See also PHOTOGRAPHIC CHEMICALS. This is from the Online CSIS
Regards Labbie

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Re: Sodium thiosulfate

Post by bigmack » 12 Aug 2019, 14:55

Labbie wrote:
12 Aug 2019, 14:04
sodium thiosulfate*
sodium hyposulfite
hypo
7-12
1
2
3
4
5
6
-
NR

Not Hazardous -
-
7772-98-7 Moderately toxic if ingested. Forms toxic gases on contact with acids and on heating. Photographic fixer. Used in crystallisation experiments and redox titrations. Small quantities can be sued for chemical gardens and crystal growth experiments with students Years 5-6.
Disposal: Waste solutions of this chemical may be disposed of down the sink (to sewer).

Q-Stores

15

See also PHOTOGRAPHIC CHEMICALS. This is from the Online CSIS
:cheesy:

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Re: Disposal of Sodium Thiosulfate?

Post by Labbie » 12 Aug 2019, 15:02

Oh well done Bigmack, a typo from the DoE, I did paste & Copy
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Re: Sodium thiosulfate

Post by Merilyn1 » 12 Aug 2019, 15:31

astagni wrote:
12 Aug 2019, 13:04
I'm confused!! !
Needed to label some more Sodium thiosulfate containers. Prevously to subscribing to Riskassess, I've used Chemwatch. Riskassess says "not classified as hazardous", blue dot etc However Chemwatch lists it with "warning' and ' toxic to aquatic life'. Interested in any comments
Go with the Riskassess guidelines. Chemwatch gets it wrong so many times. I have trays of 1M HCl with old Chemwatch labels (I'm gradually replacing them) with some saying non-hazardous, some corrosive and some Warning or Dangerous.

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Re: Disposal of Sodium Thiosulfate?

Post by Labbie » 17 Aug 2019, 14:01

If you are a private school, see your Head teacher, and get a classified answer on Riskasses or chemwatch, not both. And stick to it. If you are a DoE school you have no choice, its CSIS chemical safety in school, and that is it.
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Re: Disposal of Sodium Thiosulfate?

Post by Kathryn » 19 Aug 2019, 12:40

I think part of the trouble with Chemwatch is they are writing SDS for large quantities as in manufacturing or industry. Using hundreds of kg's is quite different from the amounts that we use in schools.
Kathryn

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Re: Disposal of Sodium Thiosulfate?

Post by Labbie » 19 Aug 2019, 13:18

This is so very true, before I retired we asked that question to chemwatch, and they said in the future they may have a part for DoE schools. But I would not hold my breath.
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