Learn how to dispose of ferric chloride in your DIY circuit board manufacturing process so that the material doesn’t become a contaminant.
Ferric chloride is a valuable chemical in the acidic etching of PCBs and water treatment.
But the chemical is caustic, and poor disposal can lead to environmental pollution.
So how do you dispose of it, and what are some of the material’s alternatives?
Find out all that from our detailed guide below.
Why is ferric chloride so commonly used?
It’s a chemical that is essential in the coagulation of dirt particles during water treatment. Other uses include the following:
- Treatment of sewage
- It’s also an effective etching agent in the manufacture of circuit boards via the wet etching technique.
- Lastly, ferric chloride is a raw material in manufacturing other chemicals.
One of the properties of ferric chloride is that it is non-combustible and slightly soluble in water.
So what makes it the best choice for water treatment applications? First, the chemical is cheaply available and has a wide range of operations.
Pros and Cons of Ferric Chloride
Pros of Ferric Chloride
- It is an effective reducing agent, thus ideal for removing various metals from water.
- The chemical can operate over a wide pH range. This means you don’t need to be highly considerate of your pH, as it will remain stable under all conditions.
Cons of Ferric Chloride
- The raw materials of ferric chloride (hydrochloric acid and spent iron liquor) are often subject to price fluctuations. This means that ferric chloride’s price can increase anytime.
- Also, it is a highly corrosive chemical primarily because of its acidic properties. It, therefore, requires special handling equipment. Otherwise, if you don’t take caution when handling it, the chemical can cause leakages and accidents.
Health and Environmental Risks of Ferric Chloride
Ferric chloride in a flask.
- Ferric chloride can ‘eat’ metals due to its corrosive properties. Also, it is potentially harmful to humans as it can cause skin burns and eye damage if it comes into contact with these parts.
- Also, you cannot dispose of Ferric chloride safely in water as it is highly toxic to aquatic life.
- Handling the chemical requires extreme caution as it will likely cause spills and damage to equipment. In mild cases of exposure, it can lead to equipment staining.
- You’ll likely find heavy metals and others such as chromium, zinc, and manganese in ferric chloride. Primarily, this is because these materials are evolved in the ferric chloride manufacturing process. Therefore, it is hard to come by pure ferric chloride, meaning you cannot predict its reaction due to the contamination.
How to Dispose of Ferric Chloride
Here are the steps for the proper disposal of Ferric Chloride.
Wear Appropriate Gear
The primary safety precaution is always wearing safety equipment and gear when dealing with this toxic chemical.
Chemical Worker’s Goggles
A worker wearing a respirator.
You must, by all means, prevent ferric chloride from coming into contact with your eyes as it is quite harmful in the following ways:
- Slight contact with the eyes will cause burns around the eye area and extreme pain.
- If a splurge of the chemical contacts your eyes, you may even suffer permanent blindness as it is highly corrosive.
The solution is to wear a pair of chemical workers’ goggles as they are essential in keeping any liquid or powder from the chemical away from your eyes.
As an added precaution, always use a face shield when dealing with ferric chloride, as this gear is highly effective in keeping chemical splashes away from you.
Chemical Protective Clothes
Wearing protective clothes.
In addition to the worker’s goggles, it would also help to wear clothes that the chemical is unlikely to corrode.
For instance, you can wear heavy trousers, a rubber apron, a long sleeve shirt, and gumboots.
To prevent skin burns, no part of your body should be exposed when dealing with ferric chloride.
In addition, consider using clothes that you’re ready to dispose of if stained, as ferric chloride is renowned for its highly staining properties.
Dust Mask and Pair of Gloves
You also need to keep the chemical particles away from your respiratory system, and a dust mask is critical to this process.
It will shield the delicate parts such as your nose, mouth, and eyes from the chemical’s fine particles.
As an added precaution, consider using a respirator instead of a dust mask when dealing with a large volume of the chemical.
A respirator is more effective than a dust mask and guarantees more protection.
Lastly, don’t touch ferric chloride without a pair of surgical gloves or any other available rubber gloves.
Control the Solution’s pH before Disposal.
An Acid-Base Reaction.
You must neutralize the acuity of ferric chloride before disposing of it by mixing the chemical solution with a base.
Some of the commonly available bases you can use include the following:
- Sodium hydroxide (caustic soda)
- Sodium carbonate (sodium bicarbonate)
Ideally, you must test with a pH meter before mixing the ferric chloride with a base to determine if it has achieved neutrality.
We recommend sodium bicarbonate as it’s easily available. The correct pH should be between 7 and 8.
Anything above or below this means it’s either acidic or basic and thus can be corrosive upon disposal.
Separate the Solid from the Solution
Separate the solute from the solvent via the decanting process.
Remember, we’re dealing with a ferric chloride solution used to etch a copper board in making a circuit board.
Therefore, your ferric chloride solution will comprise two main parts:
- Ferric chloride solution
- Copper sludge
You need to separate the two before disposal via the following steps.
- First, you need to decant the solution into another container while taking caution that no solute (copper sludge) enters the second container.
- This process is critical as it allows you to easily dispose of the liquid without the risk of spillage, which can be harmful as it is still highly toxic.
- Next, dilute the solution with water before pouring it down the drain into a septic tank.
- The dilution will significantly help neutralize the ferric chloride solution, reducing its toxicity to the drain pipes. Once it is fully neutralized, you can pour it into the drain.
- Test using a pH meter or do a litmus test to ascertain neutrality.
- Put the copper sludge containing iron particles in a safe package. We recommend the HAZMAT safety disposal receptacle primarily because the containers are airtight, ensuring that no fumes of the chemicals escape.
- Lastly, take the solute in the bag to a disposal facility to remove the substances and recycle the package.
What are some substitutes for ferric chloride?
Ammonium Persulfate chemical composition.
Copper sulfate. The following are some of the materials you can use in place of ferric chloride in water treatment:
However, these alternatives may not work for etching like Ammonium Persulfate.
This is the best alternative to ferric chloride thanks to the following features:
- Its solution is transparent, which ensures you can witness the entire etching process.
- Unlike ferric chloride, it doesn’t form stains on clothes.
- Moreover, you can use it in all types of tin PCBs as it has tin etch-resist features.
Diluted hydrogen peroxide and copper salts like cupric chloride also work well in etching hence a handful alternative to ferric chloride.
You must be careful when disposing of ferric chloride solution as it is toxic and corrosive because it is acidic.
In the article, we have highlighted the preparation process of ferric chloride before disposing of it.
The rule of thumb is to uphold safety protocol, such as having safety gear on to ensure safety during this process.
Thanks for your time. We ask you to always do the correct disposal of your etching solution.