Ferric Chloride

[wireless_john]

For many years I have been making my own PCBs with a Dalo etch resist pen and then etching with ferric chloride.

My father was a pharmacist and in the 1980's used to bring me bottles of ferric chloride as in the pictures. The plastic bottle is unopened, and I have quite a few glass ones! The ferric chloride in the plastic bottle is four times stronger than in the glass bottles.

When I'd finished etching I used to pour the liquid back in the bottle and this would settle and leave a sludge in the bottom. I assume the sludge is the copper in some form that's been removed by the etching process.

So my question is, what's left in the bottle? Is it still the same ferric chloride sitting on top of the sludge or is it less potent in some way?

I have reused it in the past and it still seems to work but I wonder for how long.

[ThePillenwerfer]

This is from school-boy Chemistry that I don't claim to have fully understood even at the time but it'll be interesting to see if I'm right.

I'd guess that the ferric chloride becomes copper chloride. The iron has to go somewhere so I bet that's what's at the bottom of the bottle.

[kalee20]

Not quite.

Copper is less reactive than iron, so no way would it displace iron from ferric chloride (the reverse is more likely to happen). What does happen is the ferric chloride is reduced to ferrous chloride (which is also soluble in water) and chlorides of copper are created (which aren't).

2FeCl3 + Cu → 2FeCl2 + CuCl2

and

CuCl2 + Cu → 2CuCl

So you end up with some CuCl2 (in solution) and some CuCl (which is only slightly soluble in water, so is a good candidate for the sludge).

Unless anyone has any better suggestions!

[wireless_john]

Thanks for your replies. I wish I'd asked my Dad whilst he was still alive!

I also don't know what to do with it. Very reluctant to pour it down a drain.

John

[The Philpott]

It would be worth looking at your local council website. There's a ridiculous amount of regional variation but sometimes you get a nice surprise- like when i got a bag of asbestos taken away from the house FOC. They are generally increasingly aware that if they don't co-operate certain people are prone to just dump things belligerently.

If only the *Copper Chloride could be reliably separated from the Ferric Chloride, you'd have * insecticide, fungicide, herbicide..

Dave

[Philips210]

Hi.

In more recent times when I've needed to dispose of spent ferric chloride, I've always taken it to our main recycling centre, where they have a facility for accepting a range of different chemicals. It's obviously important to correctly label the item before handing it over to them. Fortunately, there's no charge for the service and long may that continue.

Regards,
Symon

[David G4EBT]

There’s a natural assumption that putting chemicals down the drain can only be harmful, but in fact the main industrial use of ferric chloride is in waste water treatment. It therefore seems that emptying a small quantity of ferric chloride down the drain will do nothing more than add a minuscule amount to that with which waste water will be treated in due course.

https://chlorine.americanchemistry.c...-Out-of-Water/

[Hartley118]

Back in the day, one or two of our businesses had pretty substantial electroplating plants. The disposal policy then was extreme dilution of the chemicals prior to pouring down the drain - i.e. lots of water. I suspect that policy has long since been superseded, but it’s an approach that I still use at home if I have small quantities of reasonably harmless chemicals for disposal.

Martin

[joebog1]

Originally Posted by David G4EBT

There’s a natural assumption that putting chemicals down the drain can only be harmful, but in fact the main industrial use of ferric chloride is in waste water treatment. It therefore seems that emptying a small quantity of ferric chloride down the drain will do nothing more than add a minuscule amount to that with which waste water will be treated in due course.

Assuming of course that you have plastic plumbing. Its quite common in aus to find copper waste pipes in older houses.

Joe

[Bazz4CQJ]

Originally Posted by Hartley118

Back in the day, one or two of our businesses had pretty substantial electroplating plants. The disposal policy then was extreme dilution of the chemicals prior to pouring down the drain - i.e. lots of water. I suspect that policy has long since been superseded, but it’s an approach that I still use at home if I have small quantities of reasonably harmless chemicals for disposal.

"Back in the day" (in the 1960's) I recall the River Aire and the canal in Leeds were pretty much devoid of any type of living thing, and I strongly suspect the same was true throughout the UK. Things have improved since then.

I think that the OP's concern lies with the soluble copper salts which are present in the solution. Even if the quantity is small, I think he is to be commended for seeking a benign way of disposing of it.

As for the use of ferric chloride to purify water, is there a record of such usage in the UK, or is that just true of the 'land of chlorinated chicken'?

B

[Craig Sawyers]

Same with the Tyne. Everything went into it - sewage, industrial waste, and the coal dust washings from the pits. It used to be called the Coaly Tyne because of the coal waste, but I remember the foul smelling sludge revealed at low tide - basically raw sewage.

Remember the coal waste conveyor at the coast in Get Carter? Well that was typical of the day.

Now (at least last time I was back) it is really clean again. The use as a waste disposal system are long gone, just like the pits and heavy industry.

Craig

[Terry_VK5TM]

Mix it with lime.

Add just enough to turn it into a solid and it can be disposed of in normal household waste.

[David G4EBT]

Originally Posted by Bazz4CQJ

I think that the OP's concern lies with the soluble copper salts which are present in the solution. Even if the quantity is small, I think he is to be commended for seeking a benign way of disposing of it.

As for the use of ferric chloride to purify water, is there a record of such usage in the UK, or is that just true of the 'land of chlorinated chicken'?

B

As to safe disposal, this is advice given by a UK company who supply ferric chloride for waste water treatment and drinking water purification:

Quote:

What neutralises ferric chloride?

The solution must not be put down the drain because of residual copper ions left in it. To make it safe for disposal, you can add sodium carbonate (washing soda) or sodium hydroxide to it to neutralise it, until the pH value goes up to between 7.0 and 8.0, testing it with indicator paper.

End quote.

As to 'is there a record of its use in the UK?' Yes - its use seems to be pretty standard.

Quote:

Why is ferric chloride used in water treatment?

Ferric chloride is the coagulant of choice for many industrial and sanitary wastewater treatment applications, due to its high efficiency, effectiveness in clarification, and utility as a sludge dewatering agent. The chemical leaves a slight residual colour and offers very good turbidity removal.

Ferric Chloride is effective primary coagulants based on trivalent iron (Fe3+), excellent for drinking water production, wastewater treatment applications such as phosphorus removal, struvite control and sludge conditioning. The products also control the formation of hydrogen sulphide and prevent the formation of odour and corrosion.

End quote.

Source:

http://gpcclearsolutions.co.uk/ferric-chloride/

http://gpcclearsolutions.co.uk/about-us/

Also:

Quote:

Clean and waste water treatment in the UK is a highly regulated sector covering all companies that provide water and sewerage services – these regulations have been in place since the industry was privatised in 1989 to ensure that consumers receive high standards of service at a fair price. In addition to this many private companies are required to treat water – either for use in their own processes or before discharging as waste.

Ferric Chloride has a wide range of applications across a variety of industries – examples below:

• Water treatment
• Removal of suspended solids & phosphorous
• Flocculation agent
• Metal treatment – used for etching
• Biogas – used for bonding of Hydrogen Sulphide
• Standard strength is typically 40% as FeCl3
• Dilutions may be possible on request
• Product available to meet BS EN 888:2004 – Treatment of Water for Human Consumption

End quote.

Source: ICL, who manufacture ferric chloride at their site in Runcorn, Cheshire:

http://www.icgl.co.uk/sector/water-treatment/

http://www.icgl.co.uk/about-us/

I gave up using ferric chloride long ago - it's horrid stuff.

I use sodium persulphate which is a white crystalline power which looks rather like sugar.

It makes a colourless liquid, which turns pale blue in use and leaves no residue. The etchant can be stored for re-use - the batch that I'm still using was made in March 2018 and has etched maybe 30 small PCBs. I discovered that when in solution, it has to be stored in a warm place. I used to store it in my unheated garage and when cold, large crystals like ice cubes formed, although they're not ice, and don't then dissolve.

The downside is that it has to be at 40 - 45 degrees C to be effective. (I heat it with two 75 Watt aquarium heaters with the thermostats overridden). It could be made with hot water at that temperature, but couldn't be stored for re-use unless re-heated.

It's supplied by a specialist chemical company, delivered in heavy gauge PVC 'bottles' in a heavy duty card tube:

https://www.ebay.co.uk/itm/1kg-Sodiu...3D220721707800

Hope that's of interest.

[David G4EBT]

Originally Posted by joebog1

Assuming of course that you have plastic plumbing. Its quite common in aus to find copper waste pipes in older houses.

I meant down the outside drain - not the sink in the house. If I did that, I'd get found out.

My wife's ability to discover what mischief I've been getting up to when she's out shopping exceeds that of a forensic scientist!

What I wrote above is not good practice for disposal, as I discovered on looking into it further. (See post #13 - 'neutralise with washing soda').

[David G4EBT]

Originally Posted by Craig Sawyers

Same with the Tyne. Everything went into it - sewage, industrial waste, and the coal dust washings from the pits. It used to be called the Coaly Tyne because of the coal waste, but I remember the foul smelling sludge revealed at low tide - basically raw sewage.

Remember the coal waste conveyor at the coast in Get Carter? Well that was typical of the day.

Now (at least last time I was back) it is really clean again. The use as a waste disposal system are long gone, just like the pits and heavy industry.

Craig

A bit off topic from ferric chloride, but in terms if river pollution, recent report stated that there are no rivers in England that are safe in which to swim.

Apparently, what's known as 'wild swimming' has become hugely popular.

Hundreds of wild-swimming clubs have formed across the country in the past two years, according to the Outdoor Swimming Society, whose membership has climbed to more than 70,000 from only a couple of hundred a decade ago. Those who swim in infected waters face danger from bacteria, including E. coli, salmonella and listeria. Diseases such as leptospirosis, septicaemia and hepatitis A are also linked to sewage pollution and can be fatal.

The Times newspaper and others recently reported thaqt evidence of raw sewage being dumped in rivers, including close to spots used by swimmers and anglers, via emergency outflows that should be used only in exceptional storm conditions. One such outlet released raw sewage into a vulnerable trout river in Yorkshire after a rainfall of only 1mm.

Parents of young children who were playing in the River Wharfe in the spa town of Ilkley, West Yorkshire, during hot weather last month were unaware of how sewage outflows upstream were likely to have poured raw waste into the water after thunderstorms.

The sources of pollution in England’s rivers include industry, agricultural run-off and legacy contamination from mines. However, the agency says that more than a third of rivers are failing to meet ecological standards because of sewage. There are 16,000 sites across the country where water companies are legally permitted to spill untreated waste into rivers.

More about it here:

https://www.thetimes.co.uk/article/p...ming-q8thdx678

There are over 18,000 sewer overflows across England and Wales – and about 90% of them discharge raw sewage (mixed with rainwater) directly into rivers. Overflows are supposed to happen only during extreme rainfall, to prevent sewage backing up into homes. But 8-14% of overflows are spilling sewage into rivers at least once a week, and between a third and a half at least once a month.

Source:

https://www.wwf.org.uk/updates/40-ri...olluted-sewage

According to a report by Greenpeace, in terms of pollution from plastic, the River Mersey is the most polluted in the UK:

https://www.bbc.co.uk/news/uk-englan...yside-48690163

[lesmw0sec]

Originally Posted by joebog1

Assuming of course that you have plastic plumbing. Its quite common in aus to find copper waste pipes in older houses.

You have plumbing? When I lived near Beaudesert, the outlet from the bath was a hole in the floor over an old tank under the house, with the dunny down the garden - happy days!

[wireless_john]

Thanks for your replies. I'll stop pouring it back in the bottle now I think! The local recycling centre don't want it and didn't have any ideas about what to do with it so I'll email the County Council and see what they say.

I have a small amount of paraffin in a 5 gallon plastic container from the days when we had a paraffin heater and they didn't want that either. In fact, and I kid you not, they told me to pour it down a drain!!!!

I won't be doing that!

John

[The Philpott]

John,some plastics do embrittle after holding paraffin or meths for a long time- i can't guarantee PE is immune from that- and you only find out when you come to move the container! Personally i would decant into newer,smaller containers and hang onto it, but that's partly because when degreasing or unseizing things i can't use diesel.

Dave

[CambridgeWorks]

Be careful giving authorities too much information. They might start sticking their nose in. Around 1990, I was asked by the environment agency what I would use for hygiene control growing mushrooms in polytunnels. I gave them the name of a common mushroom house disinfectant. I was then informed that as a disinfectant it was a class 1 hazardous substance and all waste water (including rain near tunnels and car park) would need to be collected, held and disposed of by a licensed waste contractor as it could possibly be contaminated! This was at a massive cost and unviable.
Rob

[wireless_john]

Originally Posted by The Philpott

John,some plastics do embrittle after holding paraffin or meths for a long time- i can't guarantee PE is immune from that- and you only find out when you come to move the container! Personally i would decant into newer,smaller containers and hang onto it, but that's partly because when degreasing or unseizing things i can't use diesel.

Dave

Thanks for that. I have decanted some into a glass jar. The plastic container originally held some sort of alcohol/spirit, I forget what now, that my Dad used where he worked. We had quite a few of the containers and I and some of my Naval friends at the time in HMS Collingwood used them to ferment wine and brew beer! I've looked at it and it seems OK.

John