Starting up some CuBenz now:
Got my CuSO4 in today (awesome fast shipping via US pigments), 500ml H2O with 36 grams per 100ml with heat on the solution to saturate it. Still on the hotplate stirring so I'll check my saturation in a bit.
Looking at about 500ml H2O with 25 grams Kbenz per 100ml to start and will increase saturation rate with no heat.
After that I'm looking to crash both in an ice bath at 0 C. I've got plenty of both chems now and I'll work the methods so I can post up the best results with pictures.
Update: Went with two different methods with this batch, dissolving the K2SO4 out in a water filter and dissolving the CuBenz out in a EtOH filter. The alcohol route seems to be faster and uses less volume opposed to the H2O but is it cost effective? Probably not since I'm ending up with waste EtOH with trace amounts of CuBenz. Putting the EtOH mix on the stirrer (before filter but after first settling)to better dissolve the CuBenz. Perhaps heating and cooling to crystalize out the CuBenz would be a better idea... but I'll mess with it a bit more this weekend.
#2: Checked with a post with rec.pyro and for the most part I followed it.
To get pure copper benzoate, I recommend two things. After
mixing copper sulphate with either sodium banzoate or potassium
benzoate, cool the solution to 0 degrees C -- copper benzoate
is barely soluable in water at 0 C, so you will get the best yield
this way. Then wash the copper benzoate precipitate in alcohol
to remove the traces of sulphate. Copper benzoate is completely
insoluble in alcohol, and sodium sulphate and potassium sulphate
are both soluable.
So that brings up an interesting point, CuBenz, being insoluble in EtOH is left while the K2SO4 is diluted out- what IS CuBenz soluble in? K2SO4 washes out easy enough via a seperator (I have a 2 gallon glass bowl that water flows through and has a filter on one side to catch sediment). The two methods I tried yielded different color materials. One, using water only, is a fluffy light blue and holds a lot of water. The second, with EtOH, is a deeper pastel blue- but not fluffy at all.
Both are drying over night at 120 degrees currently and I'll grab some pictures in the morning.
Edited by Dr Boom, 17 July 2010 - 01:22 AM.