Chemical Rust Removal from Tools etc

[old man emu]

There are several ways to remove rust from tools, or to release frozen fasteners in smaller components. You can employ electrolysis or chemical methods. I want to show you a cheap chemical method using a solution made from chemicals available from your local supermarket.

 

The formation of rust can be described symbolically as  Fe²⁺ + 2 H₂O ⇌ Fe(OH)₂ + 2 H. Fe³⁺ + 3 H₂O ⇌ Fe(OH)₃ + 3 H. Chemical rust removal involves the use of an acid solution to remove iron oxide, Fe(OH)3 . While it is possible to apply an acid directly to the rusted metal, damage to the surface of the metal can be caused through spillage. A better method is to use chelating agents, which are chemicals capable of forming stable, water-soluble complexes with metal ions, particularly iron ions found in rust. 

 

A well-known commercial rust removal product employing chelation is Evapo Rust. You can buy it from motor accessory shops for a tad under $70.00 for 5 litres. However, if you don't need that much, or if you need a whole lot, I have found a DIY recipe that is cheap and just as effective, and the components can be bought at your local supermarket. The beauty of this solution (and Evapo Rust as well) is that it can be poured back into its container after use and reused, provided you filter it through a cloth to remove any solids when returning it to the container. 

 

This citric acid cost me $5.00 at Woolworths. I had bicarbonate of Soda in the pantry.

 

Just to show you how effective this DIY solution is, I threw a pair of secateurs and a strip of metal wall tie into some and left them for about 24 hours.

 

This is what I started with: and this is the result: 

The things came out of the solution with a black coating which I removed with a wire brush under running water. The effort in brushing was no more than that you'd make brushing your teeth.

 

So, what's the recipe?

Ingredients:

1. 1 litre warm to hot water
2. 100 gms citric acid
3. 63 gms sodium bicarbonate*
4. 1 teaspoon dishwashing liquid.

* In place of the sodium bicarbonate, you could use 40 gms sodium carbonate, or 30 gms sodium hydroxide

Mixing:

1. Pour the water into a plastic 9 litre bucket.
2. Add the dishwashing to the water, but don't make froth.
3. Add the citric and sodium bicarbonate alternately in small amounts. The mixing of the two will fizz like an Alka-Seltzer, which is why you do it in a 9 litre bucket
4. Let the solution sit until the froth breaks down, then pour the solution into a container that can be sealed.

 

I didn't come up with this recipe. Here is the YouTube video.

 

 

 

 

 

 

 

[onetrack]

It's a pretty stupid idea to add sodium bicarbonate and citric acid together - because one is a strong base and one is a strong acid, and they react strongly and neutralise each other, to produce water and carbon dioxide.

 

I've been using citric acid for rust removal for over 40 years and it works just fine by itself. You just take the item out of the solution and pressure wash it, and if it's still not fully cleaned, you return it to the bath for more acid action.

The important thing with citric acid is keeping the acid bath covered, so no sunlight can access it. Sunlight breaks down the citric acid fairly rapidly, and it then loses its rust removal effectiveness.

 

If you really want to improve the cleaning, you use an amine such as EDTA. This amine is called a chelating agent, and it's very effective at rust removal and improves the performance of citric acid.

You don't need much of it, because it works so well, and this is a good thing, because it's bloody expensive! The commercial rust removers such as Evaporust use amines, and they just charge huge amounts for a small amount of EDTA.

 

https://allchemical.com.au/shop/edta-disodium-salt/

 

https://brainly.com/question/30252282

 

Edited September 13 by onetrack

[old man emu]

10 hours ago, onetrack said:

It's a pretty stupid idea to add sodium bicarbonate and citric acid together

That threw me, too. Of course the two will neutralise the solution of the other. However, there is a chemical called sodium citrate. Sodium citrate may be used in the synthesis of magnetic Fe3O4 (magnetite) which is water soluble. Citrate forms a variety of molecules with ferric ions. Ferric citrate or iron(III) citrate describes any of several complexes formed upon binding any of the several conjugate bases derived from citric acid with ferric ions.

 

Most of these complexes are orange or red-brown. That is probably the reason that the clear solution you start with goes yellowish after it has reacted with the rust.

 

 So I guess that adding the bicarb and citric acid is simply a way to create sodium citrate.

[willedoo]

Sounds like it would be a lot quicker than a molasses bath.

[old man emu]

17 minutes ago, willedoo said:

Sounds like it would be a lot quicker than a molasses bath.

Where are you going to find mole asses to bath?

[nomadpete]

Don't you wash your moles, OME?

I am shocked.

[pmccarthy]

No, its moll asses. Much more attractive.

[Marty_d]

36 minutes ago, pmccarthy said:

No, its moll asses. Much more attractive.

Only when washed.

[old man emu]

Take a quick Avogadro at this: One mole contains exactly 6.02214076×10²³ elementary entities (approximately 602 sextillion or 602 billion times a trillion), the amount of substance that corresponds to the number of atoms in 12 grams of Carbon.

 

Avogadro' number, that 602 sextillion thingy, is named in honour of Amedeo Avogadro  (9 August 1776 – 9 July 1856) was an Italian scientist, most noted for his contribution to molecular theory, known as Avogadro's law.

 

[pmccarthy]

Wouldn’t want to meet him in a dark alley.

[nomadpete]

6 hours ago, old man emu said:

Avogadro at this: One mole

I was wondering how long it would take OME to start pontificating about Avogadro's famous moles

[Litespeed]

Avogadro's mole is fundamental to all the advances in chemistry, physics, biochemistry  and medicine in our modern world. 

 

It is one of the greatest discoveries of human history by creating molecular sciences. Without his mole, we would still be living in the steam age, disease and starvation would be our miserable lot, before a old age death at 35.

 

It made "Science" possible rather than a hotspotch of naturalists and philosophical societies. 

 

He deserves to stand on the shoulders of Newton and Einstein who would happily admit his mole created modern life. 

 

 

 

 

[facthunter]

Everyone should be familiar with Avogadro's Hypothesis.. People who know no science are a menace to us all.. Nev

[willedoo]

I know avocados.

[old man emu]

Is Ava Cardo related to Ricky Ricardo?