Sciencemadness Discussion Board

Calcium Nitrate (15.5-0-0) Filtering results - very dirty solution..

RogueRose - 4-11-2015 at 03:56

Wanted to find how much of the 15.5-0-0 is water and other contaminates so dissolved at about 2:1 (fert:water) ratio (works MUCH better is hot water is used - close to boiling..) and did a gravity filter using a 2L bottle. Starting at about 170-190 degrees and ending ~90-100 after dissolving (endothemic reaction effect).

calnit7.jpg - 112kB

After about 30-60 mins of settling:
calnit5.jpg - 152kB


Cotton pads were staggered about 1 cm to the right from the one below it and stacked about 9-12 pads thick, then rolled pads into a tight cylinder-ish form and squeezed it into the mouth of the bottle. It is a pretty tight fit. Poured calnit solution in and let sit above receiving jug. No solution worked through filter so submerged mouth of funnel filter in water for ~30 secs to allow filter to get soaked. This allowed full saturation of cotton and after replacing on receiver jug it was left alone for gravity (or capillary action?? or both??) to do its thing.

Filter speed started at about 1 drop / sec and gradually slowed. IDK if the cotton filter was too tight but I suspect it would have been faster had fewer pads been used. Filtration may have been faster had a pre-filtering been done but it seemed the large majority of the "gunk" was floating near the surface so IDK if the filter ever had to deal with the large amount of "gunk" as it seems to have remained on the sides as the level dropped.

calnit4.jpg - 101kB

This is pic with coffee filter which was tried as pre filter, but it clogged quickly and didn't seem necessary.

calnit2.jpg - 109kB



This is the final outcome of about 18-24 hours for just under 2L of liquid. Filtrate is about as clear as the spring water that came in the bottle! (although I'm sure small particles exist).

calnit1.jpg - 264kB


Solution mass/volume = 100g/70ml or 1.429g/ml

Not sure how to go about recrystalizing as don't know if degradation of compound will happen with boiling. As stands now the plan is to boil down until thick slush is left and then move to oven on warm (~150-170) until water is driven off. No vacuum aparatus or distillation setup is available (very minimal lab setup - stove, pans & jars, lol...) Any suggestions on how to do this, anything to be aware of or tips for success? What should the final product look like?

As far as producing a pure product, I considered doing something like dissolving in alcohol, filter, then evaporate?

RogueRose - 4-11-2015 at 04:48

As far as the scum on top of the filtering "funnel", is any of this stuff actually beneficial to the plants when the product is used as a fertilizer? I read that there is often alumina and iron oxides in the prills and I am guessing that is partially what floated to the top.?


The evap went pretty well I guess. Probably would have gotten better results had I evap'd slower. When H2O was almost gone, pan removed from heat and continued stirring & water continued to evap. Spooned mix onto glass plate - looks & feels like icing sugar.

calnit8.jpg - 80kB

After cooling, substance is very hard.
calnit9.jpg - 101kB


Total weight is 60.2g
70ml solution @ 100g = 60.2g recrystalized + (39.8g H2O)
39.8g = 39.8ml or cc
70ml solution - 39.8ml H2O evap'd = 30.2ml or cc of CalNit

30.2cc = 60.2g
1cc = 1.993g

Does this sound about correct? So what does it mean that I'm about .1g (or about 5%) heavier than the tetrahydrate?

Here is the density as per Wiki:
2.504 g/cm3 (anhydrous)
1.896 g/cm3 (tetrahydrate)

hissingnoise - 4-11-2015 at 05:57

Quote:
As far as the scum on top of the filtering "funnel", is any of this stuff actually beneficial to the plants when the product is used as a fertilizer?

It's simply a prill-coating designed to counter the high hygroscopicity of calcium nitrate!


Upsilon - 4-11-2015 at 18:15

Wow, mine doesn't contain nearly that much crap even though it is also fertilizer grade. All the impurity I have found is a very small amount of foam that floats to the top of the solution.

hyfalcon - 6-11-2015 at 05:40

Well there's greenhouse grade and field grade. Greenhouse grade is meant to be dissolved and watered in, field grade is meant to be broadcast and tilled under. Big difference in QC between the two.