Monday, 2 January 2012

After a bit of a rocky start the sparing setup is going relatively well. Last night starting at about midnight and going to about 5am we concentrated 10L from about 45 ish percent to 54 percent safely. It seems that the setup can concentrate around 10% in 5 hours (obviously this will decrease as the peroxide increases in concentration). Up until now my concentration has been on getting the setup working safely, but for the next sparge I intend to take readings of liquid level and peroxide concentration regulary. Eventually I would like to be able to calculate how long a given volume of peroxide will take to concentrate.

I have settled on a completely modular setup using 19L beer kegs. The kegs have two quick connect fittings and one large hole used for cleaning. The brilliant thing about kegs is that they have a stainless syphon going to the bottom which can be used both for bubbling air through and for getting the concentrated peroxide out for use.  To get liquid out you simply need to pressurise the keg gently through the kegs gas fitting. Its good not to have to worry about contamination from adding a sparge line and other bits to the vessel and when the sparge is complete all that needs to be done is close the keg up and put it in the fridge. The kegs also make excellent storage containers.

Initially I had intended to keep the large hole in the top of the keg closed and pipe the has out of the keg through the gas fitting. This enabled the gas to be easily piped outside and also allows for the condensate to be collected,  from which the rough rate of sparing can be calculated and also the rate of loss of peroxide. Because of the pressure drop through the dry and wet gas lines, the keg is under quite a bit of pressure and not realising this I unplugged the gas in line which caused peroxide to spray all over me. I was wearing full protective equipment it wasn't an issue but it does go to show how easily mistakes can happen. Because of that we decided to let the wet gas come out the large opening in the top of the keg so that it is not under any pressure. Bellow is a picture of me wearing my has mat suit with the setup inside. The keg and heater is inside the drum, which acts as a containment vessel in the event of a leak. Our safety protocol calls for wearing suits for bulk handling and pvc raincoats/waders with long gloves and face shields for collecting samples. We had one other incident when filling the contender where the cap wasn't porpelly on the peroxide container and some spilt on my suit. 

One thing I did not anticipate was how to deal with the vapour which comes off. I was under the impression that peroxide, like water didn't have any smell and that as long as we had good ventilation we would be fine. Well after about an hour of sparing in the workshop we all felt quite ill and had bad headaches so we had to move the setup to the doorway and have a fan to blow out the fumes. I think the strong smell comes mainly from the stabilisers


  1. If you are using a catalyst pack this is not going to work.
    You need to remove the stabilizers as well as concentrate.

    I also don't like sparging in a pressure vessel in an occupied building.
    My sparging column has a safe pressure relief vent.

    Also what are you doing to dry the sparging air?
    You wil reach equilibrium with the moisture content in the air quickly if you are not first really drying the air.

  2. Sir, I would encourage you to read more on sparging peroxide as the set up your using could be dangerous. If you were to get contaminates into the sparger bad things can happen. It is also dangerous as there is no control of where the off gasses go. Further more, you did not seem to have a containment area in case of a runaway reaction nor emergency equipment in case someone got splashed. Peroxide can be handled safely with out a lot of fuss but you must go about it the right way.

    A much safer system is the vacuum sparger. Dry clean air is drawn into the sparger through a set of dehumidifiers, filters, and low temp heaters. The air is pulled through the liquid and leaves the top via a hose that is then run through some water filters and chemical filters to scrub the last bit of peroxide out. Air leaving the system is clean, breathable, and safe. Because air going into the system is filtered there is little chance of contamination. This type of peroxide must be run through an ION EXCHANGE filer to reduce the amount of stabilizer in the now concentrated solution.