Wednesday, 30 November 2011

Its been quite a while since my last post, but don't get worried things are still happening!

I am still working on a peroxide concentrator, but I have decided not to publish any more particulars of my work because of a few reasons:

1. Its really really dangerous:
I didn't really realize when i set out just how dangerous HTP can be if you don't know what you are doing.  I have done a bunch of research and the more I do the more I realize just how dangerous peroxide is! It can be done safely with the correct precautions but I don't want to encourage anyone to attempt it if they haven't researched it for themselves.

2. Its really dangerous!

That said I am looking at using a air mover with steam to vacuum evaporate (not distill) a peroxide solution. Using an air mover was a brilliant idea that my friend Dianne Boddy (a retired engineer) came up with. For those not familiar with an air mover, it works on the same principle as an aspirator (also known as venturi pump) and is designed to propell things along tubes (one application is food in an assembly line).

One of the problems with vacuum evoperation is pulling the vacuum required, but a aspirator should help as it can operate continuously and you can pull quite a good vacuum with one, and its cheap! Usually an air mover moves product along packaging lines, so compressed air is used (to not burn the product), but they typically require quite allot of compressed air to operate so I am planing on using steam.

I had been originally been looking at sparging using a compressor and dry air using a regenerative desicant dryer and a spray syphon (like a paint spray gun) in the mixture to increase mixing of the air and solution (also Dianne's idea). Regular compressors produce air with quite a bit of oil in them, and since organic impurities can cause big problems with peroxide I don't really feel comfortable using one even with a really good filtration system. Instead I would go with a oil free compressor. The sparing system turned out to be quite expensive so I am opting for a vacuum method with a cheap air mover powered by steam.

Another way to use a vacuum would be to suck air through the solution, eliminating the contamination problem.

We have been looking at several workshops in the 100m^2 size to setup a shop. We have decided on a nice little place and are signing the lease this saturday. Here are a few pictures of the place.

I haven't been doing as much rocketry as I would like as I have been working 5 days a week for the last two weeks (to pay for the first months rent and other costs), but I will be cutting it back to 4 and 3 days over the next few weeks. I have mainly been spending my time researching and designing the peroxide concentrator.

I Imagine we will be busy for the next week moving in but after that the two things I will be working on are: getting the nitrous engine ready for another test and the peroxide concentrator.

Monday, 7 November 2011

Some Peroxide experiments

Today I was horrendously bored studying so I did a few experiments on the food grade peroxide.

1. Density: I measured the density with my new hydrometer (set of), and found it to be 1.19, which puts the concentration at about 40-45 percent. I didn't correct for temperature, and it was quite hot in the workshop so it may be higher.

2. Filtering with carbon: I tested pellets of activated carbon from a pet store, used to purify aquarium water. Short story they catalyze the peroxide. I noticed that they didn't start catalyzing imediatelly but only after a few seconds (probably when the peroxide soaked into the carbon). I found out that some activated carbon filters contain a small amount of silver to kill bacteria. That could explain its activity. I have ordered some activated carbon I know doesn't have any silver in it.

3. Filtering with ion-exchange resin: I first tested a very small amount of resin with 25 degree c peroxide to see what would hapen. After a while I couldn't see any bubbles/fire. I put a small amount of resin in a funnel with a strainer at the bottom, and ran through about 100mL of peroxide chilled to about 5 degrees twice. The TDS meter read 0.3g/L before filtering, 0.1 g/l after the first pass and 0.03 after the second pass.  The peroxide was only in contact with the resin for a few seconds each pass so the resin worked extremely effectively at removing dissolved solids. I am not sure what ions the resin have in them, but my guess would be H+ and OH-.

I was going to do a small test sparge with an aquarium air pump I bought. Thinking I might need a bigger pump in the future I ordered a 250L/Min pump. I made a simple sparging rig which was just a bucket with some silicone pipe (with holes in it) to distribute the air. The pump was wawwww overkill for only a few letires of liquid and I couldn't get the setup to not splash water everywhere so I decided that it was probably not a good idea try it with peroxide. I am going to plumb in a ball valve so I can change the flow rate of air.