How to make a lead dioxide electrode for perchlorate synthesis

Here is a way I use to make my lead dioxide electrode

Lead dioxide forms on pure lead in dilute sulfuric acid. It use the same electrolysis procedure as to make ammonium perchlorate, however parameters change.

To make it, plug a lead electrode (a tube or a plate can do the job) to the + of the generator at about +1.5 V. Use any of those materials as cathode (- of the generator): copper, stainless steel or any other materials able to conduct electricity.
The electrodes are immersed in dilute (30%) and flowing sulfuric acid. To make it flow, you can use a fitted with a little blade like a mixer. The speed should be like a little swirl touching the electrodes. This avoid pitting the electrodes.

The electro deposition is carried out with a constant current at about 100 A/m2 for about 30 minutes.

Once you have made your electrode, you should manipulate carefully because it is a bit brittle.

Preparing the electrolyte for the process

Preparing fresh electrolyte

First, prepare a saturated solution of sodium chloride. Take about 40 grams for every 100 ml of solution and bring the solution to a boil. Then allow to cool to room temperature again. Some sodium chloride will crystallize as the solution cools. The solution is then filtered to obtain a clear saturated solution.

Optionally, 2 to 4 g/l of potassium dichromate, potassium chromate, sodium chromate or sodium dichromate may be added to improve efficiency. These compounds are suspected carcinogens, so if you choose to add any, know the hazards involved and act accordingly. If lead dioxide anodes are used, do not add potassium dichromate as it will only reduce efficiency. Instead, 2 to 4 g/l of sodium or potassium fluoride may be used. Although not carcinogenic, the fluorides are nasty compounds as well and should be handled properly.

Finally, the pH of the solution can be adjusted. A pH of around 6 is optimal, but anything between 5.5 and 6.5 is reasonable. The pH can be increased by addition of sodium hydroxide solution and it can be decreased by adding hydrochloric acid. Do not use too concentrated solutions for adjusting the pH. A concentration of 2% (w/v) for both solutions is convenient to work with.

Recycling old electrolyte

When electrolyte from a previous batch of perchlorate is available the following steps can be used to recycle the electrolyte.

If the electrolyte is not clear but has solid particles in it, filter to remove these and dissolve any impure chlorate from the purification and extraction steps.
After, re-saturate the solution with sodium chloride. The procedure mentioned above in step 1 of 'preparing a fresh electrolyte' may be used.
The chromate, dichromate or fluoride if added is still present so does not need to be replenished. The pH should be readjusted, like in step 3 for preparing a fresh solution above.

Or you can prepare a saturated solution of sodium chlorate  if you have access to it. Take about 60 grams of sodium chlorate for every 100 ml of solution and bring the solution to a boil. Then allow to cool to room temperature again. Sodium chlorate will crystallize as the solution cools. The solution is then filtered to obtain a clear saturated solution.

The electrode for making perchlorate

The range of suitable electrode materials is very limited. Especially the anode material is critical. The positive charge on the anode promotes oxidation and the evolving oxygen attacks many anode materials. Several anode materials have been considered over the years. Today's main options are listed below along with a short description.

Anode materials (plugged on the +)

Platinum: The obvious disadvantage of platinum is its high price. However, platinum anodes corrode only at a very slow rate and are suitable for perchlorate production. They therefore provide an almost ideal anode material. High efficiency can be reached with platinum and processing of the electrolyte is greatly simplified.

Lead dioxide: Lead dioxide provides an economical alternative to platinum. Lead dioxide anodes can be made at home. This takes some work and effort, but the anodes are cheap, fairly resistant to corrosion even at higher temperatures and are suitable for perchlorate production.

Cathode materials (plugged on the -)

Both stainless and mild steel find widespread use as cathode materials. Brass and copper may also be used. Each of these metals is protected to a certain extent by the negative charge present on the cathode as long as they are submerged and the current per surface area is high enough. Unsubmerged parts of the cathode corrode at a high rate however due to the action of evolving gasses and droplets of cell electrolyte

How to make ammonium perchlorate : electrolysis

As I told you earlier, ammonium perchlorate (AP) is not available in all countries.
Here is a way to make it.

First, AP is made by electrolysis of a solution of sodium chloride (table salt or NaCl).
Electrolysis is made by plunging 2 electrodes (an anode and a cathode) in an electrically conductive solution called electrolyte and plugging these electrodes to a power supply.

The electrolysis of NaCl results in the production of chlorine (Cl) and soda (NaOH). After a number of complex chemical and electrochemical reactions occurs as the chlorine dissolve in the solution.

This will yield sodium chlorate (NaClO3) if you have choose to use sodium chloride in your electrolyte, you can use potassium chloride (KCl) and you will have potassium chlorate (KClO3).
But KClO3 solubility is very low compared to NaClO3 so that it will precipitate out of the solution.
Not good for making perchlorate as the chlorate needs to be in solution in order to be electrolyzed in perchlorate.

NEVER USE AMMONIUM CHLORIDE (NH4Cl) in the electrolyte because the resulting salt ammonium chlorate is very instable though very dangerous.

Now that the sodium chlorate is made, let run the electrolysis. The chlorate will be electrolyzed to the corresponding perchlorate.

Once the electrolysis done, there is sodium perchlorate in the electrolyte. To obtain ammonium or potassium perchlorate, we will use what is called a double decomposition.
Introduce, either ammonium or potassium chloride in the solution and the corresponding salt will precipitate out as their solubility is very low compared to sodium perchlorate. To finish, extract the perchlorate and let it dry in the sun.

This post was the process of making the perchlorate, further post will cover the details like the electrode's materials (very important) and recycling the solution.

How to make nitrocellulose

Nitrocellulose, also known as gun-cotton, is like black powder but more powerful and smokeless.
It is a bit more delicate to make than the other propellant I wrote about but can still be made at home.

You will need concentrated sulfuric acid (preferably 95%), nitric acid (70%), cotton and sodium hydrogenocarbonate (baking soda).
Here is how to proceed :

Chill the acids below 0°C.
In a fume hood, mix equal parts nitric and sulfuric acid in a beaker.
Drop cotton balls into the acid. You can tamp them down using a glass stirring rod. Don't use metal.
Allow the nitration reaction to proceed for about 15 minutes (Schönbein's time was 2 minutes), then run cold tap water into the beaker to dilute the acid. Allow the water to run for a while.
Turn off the water and add a bit of sodium bicarbonate (baking soda) to the beaker. The sodium bicarbonate will bubble as it neutralizes the acid.
Using a glass rod or gloved finger, swirl around the cotton and add more sodium bicarbonate. You can rinse with more water. Continue adding sodium bicarbonate and washing the nitrated cotton until bubbling is no longer observed. Careful removal of the acid will greatly enhance the stability of the nitrocellulose.
Rinse the nitrated cellulose with tap water and allow it to dry in a cool location.

You can dissolve it in acetone to make nitrocellulose lacquer, extrude it (the shape of your engine for example) and let the acetone evaporate (preferably outside) and you will have nitrocellulose in the required shape.

But beware nitrocellulose is easily ignited, it will burst into flame if exposed to the heat of a burner or a match.

How to make Ammonpulver

Now another high power propellant the Ammonpulver.

The chemicals are Ammonium Nitrate and Charcoal, all of those in a very fine powder as always.

Charcoal is very easy to find and Ammonium Nitrate is a fertilizer but in some countries it will not be so easy to find it because of its nature.

However it can be made by gently pouring nitric acid on ammonia (common household chemicals), this reaction is exothermic so be careful to not auto-ignite the mixture.
I recommend using water ammonia and diluted nitric acid as water will absorbed the heat of the reaction.

You will have a solution of ammonium nitrate you can gently evaporate on a hot plate but do not heat over 150°C because AN thermal decomposition is explosive.

Now that you have all the chemicals, mix them at a proportion of 85% AN and 15% Charcoal.

Bind it if you want and you're ready to go.

However this propellant suffer some issues, "AN/C" is harder to ignite than APCP. My advice is that you use some Rocket Candy (described last week) for the ignition.

And it is also hygroscopic (it absorbs moisture from the air), so you will have to store it in a dry container.

How to make APCP

APCP is the propellant of the Space Shuttle's solid booster and it stands for Ammonium Perchlorate Composite Propellant.

It is very a good propellant with high performance : high specific impulse (300s average against 160s for rocket candy), high thrust and is not very expensive.

The chemicals needed are, of course, ammonium perchlorate (AP) but  it is not available in many countries. You can make it at home through electrolysis of a solution of sodium chloride but requires a special electrode to have a good yield. I'll describe the process in another post on how to make your own AP at home.

The second chemicals is aluminium powder, a very fine powder (under 250 mesh) more exactly.
You can buy it on the Internet, find it in a pottery shop as a pigment or make it by putting some aluminium sheets in a ball mill for several days.

Mix well (it's very important) the two components and add a resin like HTPB. It is in a liquid form you will have to cure it. The curing agent for it is usually a polyisocyanate compound like Isonate-143-L.

The resin and the curative are the most expensive products but a little bottle can last several use.

This is the most used formula for this propellant but you can still use another binder like dextrin or Parlon.

How to make Rocket Candy

Now, here's my favorite cheap and easy-to-make propellant : the Rocket Candy.

It's my favorite because it is very easy to make, it doesn't require a binder and it has pretty good performance.

The chemicals are just potassium nitrate (saltpeter) and sugar, the same sugar you use to make a cake, in a proportion of 65% KNO3/35% sugar.

The procedure is as follow :

• Put the chemicals in water in a pan.
• Heat and bring to a boil the water.
• Heat until there's no water remaining, you should have a white slurry, here's the propellant.
• Take this slurry and put it in your rocket engine.
• You can also put 3% weight of iron oxide (Fe2O3) or manganese dioxide (MnO2) as they acts as catalysts.
• BEWARE ! Do not heat for too long or the sugar will caramelize and it is very fire sensitive. Just a spark can ignite it.

The Rocket Candy can also be used as a smoke generator but you can't dyed it.
As always if you want to make it, the chemicals are available in the right side.

How to Make Zinc Sulfur Propellant or ZnS

This propellant is composed of, like it's name means, zinc and sulfur.

As always the chemicals needs to be finely powdered. All you have to do, in order to make it, is to mix them up and use whatever binder you want.

It's not a propellant I will recommend because it has a poor impulse and incredibly fast burn rate.

However this propellant leaves a spectacular large orange fireball and smoke trail behind the rocket.

How to make blackpowder

Black powder was invented by the Chinese 2 millenia ago and used in their own fireworks and rockets to celebrate their feasts. It's the oldest propellant of History and now you understand why I had to begin with.

Making black powder is very simple but you must follow some rules if you want it to work properly.

A black powder-powered rocket. Note that it makes
a lot of smoke.

You'll require 3 different chemicals : potassium nitrate (also known as saltpeter, you can find it easily in any garden store, it's a stump remover), charcoal and sulfur. You can find them in the link I provide to the right.

Now that you have all the chemicals, crush them SEPARATELY (never crush, grind, etc the chemicals together, some composition are very sensitive and can be ignited easily) to a fine powder. This is the most important rule, the chemicals have to be the finest possible if you want a usable powder.
If the grains are coarse, the black powder will not burn correctly. To do the job you can use a ball mill or a mortar and a pestle.

Once you have the finest powders possible, mix them well with the following proportion : 75% potassium nitrate (KNO3), 15% charcoal and 10% sulfur by weight.

You can now use it as it is (for pyrotechnic purpose for example) but it needs to be binded in order to stay in the rocket engine. I never tried it but I'm pretty sure that a binder like red gum can do the job.

I don't have the habit to use black powder in my engines because I use a more powerful and easier to shape alternative to black powder. I will describe it later in the week.

Have fun with your own homemade black powder.