Guide to Distill Sulphuric Acid from Drain Cleaner

This post is just going to be posted for future use case so if I am doing a chemical procedure that requires azeotropic sulphuric acid then others can follow along without having to acquire sulphuric acid from a chemical supply vendor (which can be considerably more expensive).

Required Material

1. Sulphuric acid based drain cleaner

Recommended Materials

1. Round bottom boiling flask
2. A condenser
3. Bunsen burner or heating mantle

Process

1. To start you want to get a sulphuric acid based drain cleaner. It will say on the bottle.
2. Using a generic distillation setup as shown below (from wikipedia) add your drain cleaner solution to the round bottom flask and apply heat. Run cool water through the condenser.

3) Collect the first roughly 15% to 20% of the drain cleaner distillate then replace the collection vessel. Following this, test the distillate by adding a few drops to some form of paper like paper towel. It should create a very visible reaction. If it doesn't, keep collecting until it does. A second test is to look through the distillate and see if light can pass through it without being distorted. 4) Once it is running clear and it can react with paper, keep collecting the distillate until only around 20% of the original drain cleaner remains in the boiling flask. The distillate collected should be the azeotropic sulphuric acid (~98%). You can test this by checking the density of the distillate (get the mass of your product and the volume and divide them). The closer the density is to 1.84g/ml the more pure it is.

Warning

Concentrated sulphuric acid is dangerous. If you get it on your skin then clean off with ethanol solution or submerge afflicted areas in an ice (cold) water bath. Wiping off with small amounts of water will result in the water boiling and causing further damage. It is far safer for you to take the extra time and get enough water to submerge the area then to try and wash it off. Often movies show acids as being able to dissolve flesh in seconds, sulphuric acid may burn you but it won't cause permanent damage from only a few extra seconds. You may also use a mild soapy solution but be cautious.

Videos

Sources

1. Distillation Apparatus, no modifications. CC3.0 by Theresa Knott
2. Sulphric Acid Density
3. NurdRage purifying sulphuric acid
4. UofM First Aid for Chemical Burn