Cleaning method for fixed nitrogen flask

Cleaning method for fixed nitrogen flask
The nitrogen fixing flask plays an important role in nitrogen fixing experiments. When cleaning, it is necessary to ensure that it is clean and does not affect subsequent experiments. Based on the relevant cleaning information of the nitrogen fixing instrument and the general laboratory flask cleaning logic, the following cleaning methods can be used for reference:

Preliminary flushing
After the experiment is completed, the remaining solution in the nitrogen flask should be immediately poured out, and then rinsed with tap water to remove most of the residual substances. This can prevent residual substances from drying up and making it difficult to clean, while also reducing the difficulty of subsequent cleaning.

Targeted processing
Organic interference situation
During the distillation process, certain organic compounds are likely to be distilled out simultaneously with ammonia, which can interfere with the measurement. Some substances, such as formaldehyde, can be removed by boiling under acidic conditions (pH<1). An appropriate amount of acidic solution (such as dilute hydrochloric acid) can be added to the nitrogen flask, and then boiled to remove possible organic interference. But attention should be paid to controlling the boiling time and temperature to avoid damage to the flask.

Stubborn dirt treatment
If there is stubborn dirt in the nitrogen flask, you can refer to the cleaning method of the steam bottle cap of the nitrogen analyzer and use 20% glacial acetic acid for treatment. Inject an appropriate amount of 20% glacial acetic acid into a nitrogen flask, soak or heat it for an appropriate period of time (the specific time can be adjusted according to the severity of the dirt), and then pour out the glacial acetic acid. This method utilizes the chemical properties of glacial acetic acid to dissolve and remove stubborn dirt.

Conventional cleaning steps
Add liquid for cleaning
Add 350mL of water to the distillation flask and several glass beads to prevent the liquid from boiling. After installing the instrument, perform distillation operation and collect at least 100mL of water. Glass beads can make the liquid boil uniformly during the heating process, avoiding violent jumping of the liquid and splashing out of the flask, ensuring the safety and stability of the distillation process.

Repeat cleaning
Discard the distillate and residual liquid inside the flask, which can remove impurities and residual substances from the flask. If the cleaning effect is not satisfactory, the above steps of adding liquid for cleaning can be repeated until the flask is cleaned thoroughly. Multiple cleaning can ensure that impurities inside the flask are completely removed, ensuring the accuracy of subsequent experiments
Final cleaning and drying
Rinse with clean water
Rinse the nitrogen flask multiple times with clean water, usually 2-3 times, to thoroughly remove residual cleaning agents and impurities. During each rinse, ensure that clear water can fully contact all parts of the flask, including the mouth, walls, and bottom. During the rinsing process, gently shake the flask to allow the water to better clean the interior.

drying process
Invert the cleaned nitrogen flask and let it air dry naturally. Hot air drying can also be used, but the temperature of the hot air should be controlled between 40 ℃ and 50 ℃ to avoid hot air above 60 ℃ and prevent damage to the flask due to high temperature. The dried nitrogen flask should be stored in a dry and ventilated place for future use.