Summary for hcl pickling replacement Discussion
Effective replacement of HCl is the main question here, but the thread suggests there is no simple drop-in substitute for a 10-minute hydrochloric acid pickle. The poster says they use HCl at titration 18 when new and discard it at 8, and wants a safer option because of environmental concerns. The named answerer says 10 minutes sounds extraordinarily long for a plating shop and questions the need for such aggressive pickling. They note that hydrochloric acid itself was historically the replacement for hot sulfuric acid, and that hot sulphuric acid is one possible alternative. They also suggest trying acetic acid in the lab if HCl must be eliminated, but caution that it would be surprising if acetic acid could match a 10-minute HCl pickle. The answerer further argues that properly neutralized HCl waste should leave only salt water and precipitated metals, so the environmental hazard may be less than assumed.
Q. HI,
I AM USING HCL ACID WITH TITRATION OF 18 WHEN NEWLY MADE AND DISPOSE WHEN TITRATION COMES TO 8. DIP TIME – 10 MINS
AS HCL IS VERY HAZARDOUS FOR THE ENVIRONMENT. I WANT TO KNOW IF THERE IS ANY PRACTICAL REPLACEMENT OF HCL AVAILABLE. IF YES, PLEASE PROVIDE ME WITH DETAILS.
THANK YOU FOR SUPPORTING.
SHUBHAM
– ODISHA, India
August 17, 2024
This is a meeting place for camaraderie & sharing, not a free consultancy. So some readers don’t engage with anonymous posters.
A. Hi.
10 minutes sounds like an extraordinarily long pickle time for a plating shop. I don’t understand the need for such extreme pickling.
Actually, HCl is the replacement for hot H2SO4 which was still quite popular when I started in the industry way back when, but which I haven’t seen in use for decades now. So hot sulphuric acid is one possibility. I would suggest trying acetic acid in the lab if you must get rid of hydrochloric acid, although it would surprise me if it could replace 10 minutes in HCl 🙂
I don’t think I agree that, if handled properly, HCl is hazardous for the environment. In theory the waste would be neutralized, the metal precipitated out, and only salt water would remain, which covers 2/3 of the earth.
Luck & Regards,
Ted Mooney, P.E. RET
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