## Tuesday, August 27, 2013

### Nitrates from commercial compost 3

I bought more equipment. This is a weakness. I must resist. I have two scales and a nitrate/nitrite test kit. I am continuing the previous experiment while moving on with this one.

### Considerations

• Leaching may extract more (or less) nitrate over time.
Check at 1 and 24 hours.
• According to the literature, the evaporite is going to be a mix of [Na,K,Ca,Mg][CO3,NO2] with either the Ca or the CO3 at zero. Fe and Cl may be present as well.
We will presume it is the CO3 species that is absent.
• Potassium carbonate has the highest molecular weight of the various components of potash: 138g/mol.
• Calcium Nitrate has the highest molecular weight of the various potential components of raw saltpeter: 236g/mol.
• Suppose we have N grams of a CaCO3 precipitate. To calculate the amount of potash required to provide that much carbonate, divide by the molar mass of CaCO3 (100g) and multiply by the molar mass of potassium carbonate (138g) for a net mass multiplier of 1.38.
1.38 times the Mass(CaCO3) is the max Mass(potash) to be used.
• Suppose we have N grams of a Ca(NO3)2.4H2O evaporite. The mass divided by 236g is the number of moles of calcium nitrate. Calcium nitrate mixed 1:1 molar with potash results in 1 mole of calcium carbonate and 2 moles of alkaline nitrate. 138/236 =  0.58, thus:
0.58 times the Mass(Ca(NO3)2) is the max Mass(potash) to be used.

### Part 1, 1 hour

1. Place 1kg of compost in a stainless pot
2. Add 2 liters of distilled water
Checked: Total mass: 3kg
3. Let stand for 1 hour
4. Filter (seive and paper towels, as above)
5. Measure 1 liter of fluid
6. Get mass of solution to estimate dissolved salts, and verify by checking weight of remainder of fluid and soil
Liter:
1003g (about 3g, estimate 6g in 1kg of compost)
Remainder: 1997g
7. Perform Nitrate test
Nitrates: < 5mg/L (Well THAT sucks. Maybe it's wrong?)
8. Return the fluid to the mass

### Part 2, 24 hours

9. Let stand for 23 hours
10. Repeat mass measurements
Liter:

Remainder:
11. Test for nitrate
Nitrates:
12. Was it worth waiting the 23 hours
?

### Part 3, Analysis

13. Extract all the solution
14. Filter the solution
15. Evaporate with minimal heat
16. Weigh evaporite
Evaporite
17. Calculate the maximum potash required:
0.58 * mass(evaporite):
18. Gather the potash
19. Dissolve the evaporite in a minimum of distilled water
20. Divide the solution into two halves (S1 and S2)
21. Divide the potash into two halves (P1 and P2)
22. Add one tenth of P1 to S1
23. Observe a precipitate (hopefully)
24. Add more of P1 to S1 very slowly until no more precipitate is formed
25. Weigh the dry remainder of P1
Remainder:
26. Dry and weigh the precipitate from S1
S1 Precipitate:
27. Recalculate the maximum potash required:
1.38 * mass(precipitate)
28. If this new "maximum potash" value is lower than the mass of P2, reduce the mass of P2 to the lower maximum.
29. Add  the (possibly reduced amount of) P2 to S2
Hopefully this achieves a zero value for both calcium and carbonate, leaving only nitrates in the wake
30. Dry and weigh the precipitate from S2
S2 Precipitate
31. Compare the masses of the precipitates. They should be equal.

P.S.
The pictures here are very low res because my regular digital camera has been lost, and I am taking stills with a videocamera instead. :P