I have performed multiple runs of a new path to nitrate based on microwave treatment of an aqueous mixture of HOCl (preparation discussed below),
8.25% chlorine bleach (NaClO) and CaCl2, that was infused with N2O gas (source is an 8 gram of N2O pressurized gas cartridge designed for use in a
cream whipper which was employed here) and oxygen enriched air. A small amount of chlorate is also formed which can subsequently be greatly increased
via photolysis using the reported photocatalytic properties of the created nitrate. Actual portions employed in a particular run are detailed below
along with precautions and photos.
First, some theoretical background to provide understanding, promote safety and good yield.
One interesting paper is "Treatment of N2O impulsed microwave torch discharge " by M.Jasinski, et. al., April 2004 . To quote: "Results of using a
moderate–power (several hundred Watts) pulsed microwave torch plasma (MTP) to the conversion of atmospheric-pressure nitrous oxide (N2O) into
nitrogen oxides( NO, NO2 and N2O4) are presented." with a claimed efficiency between 70% to 90% depending on the power of the microwave. Link: https://www.google.com/url?sa=t&source=web&rct=j&...
This possible conversion of N2O is also cited in this source, "Focus on Hazardous Materials Research", edited by Leonora G. Mason, to quote : "In our
previous study using microwave discharge, N2O could be efficiently decomposed into N2 and O2 at atomospheric pressure [8]. However, when N2O is
diluted in N2/O2 mixtures was decomposed by microwave discharge, a large amount of NO was emitted due to fast reactions as N(2D,2P) + O2 --> NO +
O link: http://books.google.com/books?id=8MXX01Qw_G0C&pg=PA144&a...
So, for the purpose of constructing a net reaction for the gas phase in the radiolysis of N2O diluted in N2 and a O2 enriched mixture in a microwave,
I will assume, as an undoubted simplification, a reaction sequence that has one of the larger associated oxygen (which is supplied pre-run) and
nitrogen demands:
1/2 N2 + pulse radiation ---> N(2D,2P)
N(2D,2P) + O2 --> NO + O
O + N2O ---> 2 NO
Simplied net reaction ignoring possible benefical formation of any NO2 and several other intermediate nitrogen and oxygen species:
1/2 N2 + O2 + N2O --pulse radiation--> 3 NO
With shaking of the pulsed radiated vessel, a reaction with Hypochlorous acid:
2 NO + 3 HOCl + H2O --> 3 HCl + 2 HNO3
where the scrubbing of the NO is best accomplished between a pH of 4 to 7, and not more alkaline (see "Oxidation of Nitric Oxide in Two Stage
Chemical Scrubbers Using DC Corona Discharge" available at https://www.google.com/url?sa=t&source=web&rct=j&...
.......
Next, apparently N2O in an aqueous setting has somewhat different chemistry on irradiation. Per this source, "Chemistry of Ozone in Water and
Wastewater Treatment: From Basic Principles to Applications", on page 229, the author Clemens Sonntag cites the following reaction involving a
solvated electron (actually, rescaled by 4, link: http://books.google.com/books?id=Om_TKidEjToC&pg=PA229&a... ):
4 e-(aq) + 4 N2O + 4 H2O ---> 4 ·OH + 4 N2 + 4 OH-
where there is no nitrate formation......
With shaking, the hydrolysis of the NO2:
4 NO2 + 2 H2O --> 2 HNO2 + 2 HNO3
and, with further addition of HOCl:
2 HOCl + 2 HNO2 --> 2 HCl + 2 HNO3
Also:
4 NaOH + 4 HNO3 = 4 NaNO3 + 4 H2O
.......
Future research, microwave a mixture of CO2 and N2O, in the presence of water and a substance providing an electric discharge, in a fashion similar to
US Patent 5,266,175, link http://www.google.com/patents/US5266175, where a mix of CH4 and CO2 in a microwave has been patented by Exxon as a path to syngas (CO + H2), see
also discussion at http://www.wvcoal.com/research-development/spain-co2-ch4-hyd... . I have previously reported on SM sparking in the microwave reaction between N2O
and NaOH (see , http://www.sciencemadness.org/talk/viewthread.php?tid=32334 ) and more recently, to a limited extent, I witnessed it between aqueous NaHCO3 and
N2O. Now, as the action of uv light on CO2 has been reported to produce Singlet oxygen (to quote a source "We present a first principles study of the
carbon dioxide (CO2) photo dissociation process in the 150-to 210-nm wavelength range, with emphasis on photolysis below the carbon monoxide + O(1D)
singlet channel threshold at∼167nm.", link: https://www.google.com/url?sa=t&source=web&rct=j&... ), I suspect it may be one of the caustive agent in the patented microwave
synthesis. In the current context, the reaction of Singlet oxygen and N2O is known to form NO especially on cooling (see http://scitation.aip.org/content/aip/journal/jcp/78/2/10.106... ).
----------------------------
Sample Run Procedure (picture below of results from half of reaction, with the other half in a photolysis run):
1. Combine 154 ml of 5% vinegar and 11 g (around 5 ml) of NaHCO3 to form CO2 gas in a 3 liter vessel. Drain fluid leaving just CO2 gas.
2. Combine 209 ml of 8.25% NaOCl with 13.1 g (around 6.2 ml) of CaCl2 in a new vessel. Stir.
3. Add (2) to (1) and shake forming a bright white suspension of CaCO3. Cool to allow CaCO3 to settle, and pour out just the clear HOCl.
4. Infused the HOCl in (3) with an 8 g cartridge of N2O in a cream whipper. Shake to aid in the N2O infusion, which is limited in water.
5. In a 3 liter vessel (I used a 3 liter Poland Spring clear plastic water bottle that can standup in a microwave oven) react 28.7 ml of 3% H2O2 with
20.3 ml of 8.25% NaOCl. Drain all of the liquid leaving air enriched with O2 gas. Compress the vessel by 1/3 to allow for thermal expansion.
6. Place about HALF the contents of the infused HOCl from Step (4) into the enriched oxygen vessel of Step (5).
7. Radiate the vessel in a microwave for between 4 to 7 seconds only until the vessel is fully inflated. Remove the vessel, shake and cool by
inserting into an ice water bath as needed to implode the vessel. Caution: Do not attempt to microwave the fully expanded vessel since if the N2O
undergoes a thermal decomposition (sounds like a loud knock and the vessel acts if it was struck), the sudden rapid increase in volume from 2 N2O
---> 2 N2 + O2, coud cause a pressure eruption of the vessel.
8. Repeat Step (7) ten times or until shaking the vessel after a microwave treatment produces little compression.... |