Chemistry Forums for Students > Inorganic Chemistry Forum
making/extracting Phosphoric acid from miricle gro
NickBlack:
I'm broke, but I have a crummy lab in my basement, and some chemicals. I want to make a sodium Ion battery for funsies.
so I've decided I need some sodium iron phosphate, which I'll be making from sodium phosphate.. which means I need phosphoric acid.
I don't have phosphoric acid. I do have a few dozens of liters of urine stored up for extracting white phosphorous.. but I gotta wait till my GF id out of the house for a while before I work on that...
then I stumbled on an old box of miracle gro powder.. that contains phosphorous.. can I get at it? the box says it uses P2O5.. that's P4O10.. which should just turn straight into phosphoric acid when in water! to bad it comes with a lot of other junk.. and badly labled junk at that, so here's my work on figuring out what is (likely) in the box:
-----------------------------------------
as labeled on the container:
Guaranteed minimum analysis:
Total Nitrogen [N]------------------24%
Available Phosphate[P2O5]----------8%
Soluble Potash[K2O]----------------16%
Sulphur[S ]-------------------------4.0%
Boron[B ][Actual]-------------------0.02%
Copper[Cu][Actual]-----------------0.07%
Iron[Fe][Chelated][Actual]----------0.15%
Manganese[Mn][Chelated][Actual]---0.05%
Molybdenum[Mo][Actual]------------0.0005%
Zinc[Zn][Actual]--------------------0.06%
EDTA[Chelating Agent]--------------1.2%
personal note: EDTA (Ethylenediaminetetraacetic acid) primarily Chelates Iron & calcium
so that's probably how the Iron is Chelated
there is Ethylenediaminetetraacetic acid manganese disodium salt hydrate, which may be the way
the Manganese is Chelated..
-------------------------------------------------------------------
What the MSDS sheet says:
https://health.ho-chunk.com/sdsdocs/100336.pdf
Components-----------------------------CAS-No---------Weight %
di-Sodium-EDTA-------------------------139-33-3 <0.1
Potassium Phosphate--------------------7778-77-0 10-30
Boric acid, H3BO3-----------------------10043-35-3 0.1-1.0
Sodium molybdate, Na2MoO4+2H2O -----7631-95-0 <0.1
Iron EDTA ------------------------------15708-41-5 1.0-5.0
Manganese EDTA------------------------15375-84-5 0.1-1.0
Potassium chloride, KCl-------------------7447-40-7 10-30
Copper sulphate, CuSO4------------------7758-98-7 0.1-1.0
Zinc Sulfate-----------------------------7733-02-0 0.1-1.0
Ammoniumsulphate, (NH4)2SO4-----------7783-20-2 10-30
Urea -----------------------------------57-13-6 30-60
------------------------------------------------------------------------------------------------
off the walmart website (similar product):
https://www.walmart.com/ip/Miracle-Gro-Water-Soluble-All-Purpose-Plant-Food-1-5-lbs-Safe-for-All-Plants/16828998
Guaranteed Analysis:
Total Nitrogen (N) (24%),
Ammoniacal Nitrogen (3.5%), Urea Nitrogen (20.5%),
Available Phosphate (P2O5) (8%),
Soluble Potash (K2O) (16%),
Boron (B) (0.02%),
Copper (Cu) (0.07%),
Water Soluble Copper (Cu) (0.07%),
Iron (Fe) (0.15%),
Chelated Iron (Fe) (0.15%),
Manganese (Mn) (0.05%),
Chelated Manganese (Mn) (0.05%),
Molybdenum (Mo) (0.0005%),
Zinc (Zn) (0.06%),
Water Soluble Zinc (Zn) (0.06%).
Derived from Ammonium Sulfate,
Potassium Phosphate,
Potassium Chloride,
Urea,
Urea Phosphate,
Boric Acid,
Copper Sulfate,
Iron EDTA,
Manganese EDTA,
Sodium Molybdate,
Zinc Sulfate.
-----------------------------------------------------------------------------------
using that info, I'm guessing it has an ingredients list that looks closer to:
Ammoniacal Nitrogen[NH3-N]--------------(3.5%)
Urea Nitrogen[CO(NH2)2-N*]--------------(20.5%)
Potassium Phosphate [H2KO4P]------------(10%+) (note to self, has some cool electrical properties)
this contains ([P2O5] ~50%+ & [K2O] ~35%+)
Potassium Chloride[KCl]-------------------?%
Urea Phosphate[CH7N2O5P]---------------?%**
Ammonium Sulfate(NH4)2SO4-------------10%+ ***
Copper sulphate[CuSO4]------------------0.1%+
Zinc Sulfate[ZnSO4]----------------------0.1%+
Boric acid[H3BO3]------------------------0.1%+
Copper Sulfate[CuSO4]-------------------0.1%+
Iron EDTA-------------------------------1%+
Manganese EDTA------------------------0.1%+
Sodium molybdate, [Na2MoO4+2H2O]-----0.1%-
Zinc Sulfate [ZnSO4]------------------- 0.1%+
*I'm guessing this is just plain old Urea, not sure why they call it Urea Nitrogen here, since that term seems to be specifically used in urea in the blood)
** dissisociates into Phosphoric acid & Urea in water.
*** this also contains quite a bit of nitrogen.. but isn't listed under 'N' because of a contradiction between the MSDS and the labels..
---------------------------------------------------------------------------
Possible procedure:
unfortunately distillation seems to be out (if anyone thinks different, please let me know, I'm by no means an expert)
so I'm thinking precipitation + electrolysis:
for some reason I can't seem to find if Potassium Phosphate actually dissasociates into P2O5 & K2O or not..
assuming it does.. P2O5 (P4O10) should turn into phosphoric acid (H3PO4) when exposed to water
(P4O10 + 6 H2O → 4 H3PO4 (–177 kJ))
assuming that is all the case, the procedure should be reasonably simple:
dissolve as much miracle gro as you can into 100ml of (20'c) water.
add sodium hydroxide.
since NaHO & PO4- are both MUCH more soluble in water than things like Tri/sodium phosphate
a few different sodium phosphate salts should precipitate out.
- keep adding NaHO until nothing else precipitates out.
filter off the solids. ('hopefully this should primarily be sodium phosphate salts, but will likely have some sodium carbonate and such as well.. good enough for me anyway... hopefully)
dissolve those solids back into distilled water.
do an electrolysis in a membrane separated cell to form the Tri/sodium phosphate back into NaOH & Phosphoric acid.
can anyone see any flaws? have any suggestions? Cheers!
Hunter2:
You are on the wrong path. The label shows a mixture for a Phosphate fertilizer. Its not P2O5. Its only for calculation written, like the other compounds like K2O as well.
NickBlack:
--- Quote from: Hunter2 on February 24, 2023, 05:44:30 PM ---You are on the wrong path. The label shows a mixture for a Phosphate fertilizer. Its not P2O5. Its only for calculation written, like the other compounds like K2O as well.
--- End quote ---
if I understood you correctly, yes, there isn't any P2O5 in it's plain form in the box (despite the label saying it does) it's in a matrix with the K2O called "Potassium Phosphate" (more specifically Monopotassium phosphate, usually just called MKP)
I found it difficult to find straight answers, hence why I'm posting here rather than a vague "Fertilizer-grade MKP powder contains the equivalent of 52% P2O5 and 34% K2O" that other websites offer.
but since the liquid version of the same brand fertilizer is labeled as containing phosphoric acid, I found the idea that it does disassociate in water to form phosphoric acid to be a reasonable guesstimate.
What path would you suggest I look down?
Hunter2:
Correct, its at least a pottasiumphosphate.. In water you get pottasium ions and phosphate ions, but no phosphoric acid and pottasium hydroxide. Its the same like sodium chloride in water will not form hydrochloric acid and sodiumhydroxide.
NickBlack:
--- Quote from: Hunter2 on February 24, 2023, 06:52:07 PM ---Correct, its at least a pottasiumphosphate.. In water you get pottasium ions and phosphate ions, but no phosphoric acid and pottasium hydroxide. Its the same like sodium chloride in water will not form hydrochloric acid and sodiumhydroxide.
--- End quote ---
i mean, yes, that's how salts dissolve. I guess it's inappropriate to call a solution with H+ protons and phosphate- ions if those aren't the only ions, and it's no longer acidic, phosphoric acid? (I'm self taught, so that's a genuine question)
since sodium ions are very greedy (reactive), adding sodium hydroxide, (Na+ protons and OH- ions) it should still produce sodium phosphate salts shouldn't it? (since once they form, they should drop out of solution, no longer being dissolved) shouldn't it?
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