Method Ai created method of NaNO2 purification from curing salt

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I asked Gemini on how to extract sodium nitrite from curing salt, it said to utilize the solubility difference between table salt and NaNO2.
Does it seem legit? I think about at home purification because I just can't seem to figure out how to buy readymade sn.

Full doc link:
https://docs.google.com/document/d/1ydYjH8qHtrQ06DmjbUYEEFTVlMd6toPL0lWdbuUgDVc/edit?usp=drivesdk

Document snippet.
Purification of Sodium Nitrite from Curing Salt: A Technical Report on Laboratory-Scale Fractional Crystallization

Step-by-Step Procedure

1. Preparation and Safety Setup:

• Work Area: Ensure the work area is meticulously prepared and well-ventilated, ideally within a certified chemical fume hood. Verify that emergency eyewash and shower facilities are immediately accessible and functional.
• Personal Protection: Don all mandatory Personal Protective Equipment (PPE) before commencing any work: a laboratory coat, chemical-resistant gloves (e.g., Nitrile or Neoprene), and safety goggles or a full face shield.
• Cooling Preparation: Prepare a large ice bath in a suitable basin or bucket. This will be used for controlled cooling in later crystallization steps.

1. Initial Dissolution (Hot):

• Weighing: Accurately weigh out 800 grams of Prague Powder #1 using an analytical balance.
• Transfer: Carefully transfer the weighed curing salt into a large, clean beaker (e.g., 2L or 3L capacity).
• Water Addition: Add approximately 1800 mL of distilled or deionized water to the beaker. The precise volume of water is critical for subsequent steps. This volume is chosen to ensure complete dissolution of both sodium nitrite and sodium chloride upon heating, while also allowing the solution to become saturated with NaCl as water is later evaporated. For reference, the solubility of NaCl at 100°C is approximately 38.4 g/100 mL. Since 800g of Prague Powder #1 contains 93.75% NaCl (equivalent to 750g NaCl), theoretically, approximately 1953 mL of water would be needed to fully dissolve this amount of NaCl at 100°C. Starting with a slightly lower volume, such as 1800 mL, provides flexibility for controlled concentration.
• Heating and Stirring: Place the beaker on a heating plate equipped with a magnetic stirrer. Begin heating the mixture gently while stirring continuously. Gradually increase the temperature to near boiling, typically 90-95°C. Continue heating and stirring until both sodium nitrite and sodium chloride are completely dissolved, resulting in a clear, homogeneous solution.
• Safety Note: Avoid vigorous boiling, as sodium nitrite can begin to decompose at temperatures above 271°C , with significant decomposition occurring above 320°C. Violent decomposition and explosion hazards are present at temperatures exceeding 530°C. Ensure the fume hood is operating effectively to manage steam and any potential gaseous decomposition products.

1. First Fractional Crystallization (NaCl Removal):

• Concentration: While maintaining the solution at a high temperature (e.g., 90-95°C), slowly evaporate water by continuing gentle heating and stirring. As water is removed, the concentration of both dissolved salts will increase.
• Selective Precipitation: Due to its comparatively lower solubility and minimal temperature dependence , sodium chloride will begin to crystallize out first as the solution becomes supersaturated with respect to NaCl. This process exploits the distinct solubility curves to selectively remove the primary impurity.
• Observation: Continue the evaporation process until a significant amount of white NaCl crystals are visibly precipitated from the solution. The pink dye from the curing salt may remain predominantly in the solution or show some adherence to the crystals.
• Safety Note: Maintain vigilance for any signs of vigorous decomposition or unexpected reactions, which could indicate a loss of control over the process.

1. Hot Filtration of NaCl:

• Apparatus Setup: Immediately set up a hot filtration apparatus. This typically comprises a pre-heated Buchner funnel (preferably ceramic or jacketed glass, circulated with hot water to maintain temperature) connected to a heavy-walled vacuum flask and a vacuum pump. Pre-heating the funnel is crucial to prevent premature crystallization of the more soluble sodium nitrite within the funnel during filtration. Use fluted filter paper or filter paper specifically designed for hot filtration.
• Filtration: Carefully and quickly pour the hot slurry (the mixture of solution and precipitated NaCl crystals) into the pre-heated filter funnel. The solid residue collected on the filter paper should consist predominantly of sodium chloride.
• Collection: Collect the hot filtrate in a clean, pre-heated beaker or flask. This filtrate is now significantly enriched in sodium nitrite and contains a substantially reduced concentration of sodium chloride.
• Safety Note: Hot solutions pose a severe burn risk. Handle all glassware with extreme care, using appropriate heat-resistant gloves. The filtered NaCl solid, while primarily salt, is still contaminated with sodium nitrite and the dye, and thus must be handled as hazardous chemical waste.

1. Second Fractional Crystallization (NaNO2 Crystallization):

• Cooling: Transfer the hot filtrate from the previous step to a clean crystallization dish or a suitable beaker. Allow the solution to cool slowly to room temperature, then transfer it to the prepared ice bath (maintaining a temperature of 0-5°C) to induce controlled crystallization of sodium nitrite. As the temperature of the solution decreases, the solubility of NaNO2 drops sharply , leading to its precipitation as crystals.
• Crystal Growth: Gentle stirring during the cooling process can promote the formation of smaller, purer crystals and minimize the entrapment of impurities within the crystal lattice.
• Crystallization Time: Allow sufficient time for complete crystallization, typically several hours or ideally overnight in a refrigerator or cold room to maximize yield.

1. Cold Filtration of NaNO2 Crystals:

• Filtration: Once crystallization is complete, set up a standard Buchner funnel with vacuum filtration. Filter the cold mixture to separate the solid NaNO2 crystals from the mother liquor.
• Collection: Collect the solid sodium nitrite crystals on the filter paper. The mother liquor will contain residual impurities (e.g., remaining NaCl, dye, and some dissolved NaNO2).
• Safety Note: The mother liquor is still a hazardous chemical waste and must be handled carefully.

1. Washing the NaNO2 Crystals:

• Initial Wash: To further purify the collected NaNO2 crystals, wash them on the filter paper with a small amount of ice-cold distilled water. This step helps remove surface impurities, including any residual NaCl and adhering pink dye.
• Optional Final Wash: For enhanced purity, a very small quantity of ice-cold ethanol can be used as a final wash. Sodium chloride is notably insoluble in ethanol, even in the presence of water. However, sodium nitrite is soluble in ethanol , so this wash must be performed quickly and with minimal solvent volume to minimize product loss. This step addresses the challenge of dye removal; while the primary separation targets NaCl, the dye is an additional impurity. If the dye is water-soluble, it would largely remain in solution during hot filtration of NaCl. If it co-precipitates with NaNO2, this wash helps remove it, contributing to a visually purer product.

1. Drying the Purified Sodium Nitrite:

• Transfer: Carefully transfer the washed NaNO2 crystals to a clean, pre-weighed watch glass or drying dish.
• Drying: Dry the crystals in a desiccator under vacuum or in a low-temperature oven (e.g., 40-50°C) to remove all residual moisture. It is crucial to avoid high temperatures, as sodium nitrite begins to decompose at 271°C.
• Yield Measurement: Once thoroughly dry, weigh the purified product to determine the yield.

1. Repeat Recrystallization for Higher Purity:

• To achieve the target of 90%+ purity, it is highly probable that one or more additional recrystallization steps will be necessary. For instance, achieving 99.9% purity of NaNO2 has been reported to require three recrystallizations from aqueous solution.
• Iteration: Redissolve the obtained NaNO2 crystals in the minimum amount of hot distilled water, then repeat steps 5 through 8 (cooling, cold filtration, washing, and drying). Each subsequent recrystallization cycle should yield a purer product, although with some inevitable cumulative loss of material. This iterative process is essential for reaching stringent purity requirements.

Sodium Nitrite Purification from Salt

Purification of Sodium Nitrite from Curing Salt: A Technical Report on Laboratory-Scale Fractional Crystallization 1. Executive Summary: The Critical Imperative of Safety in Sodium Nitrite Purification This report details the methodology for purifying sodium nitrite (NaNO2) from commercial curing...

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