Inorganic Bases
by : Rahul Sharma
Inorganic Bases:
Inorganic bases are Sodium hydroxide (NaOH), Sodium carbonate (Na2CO3), Ammonium hydroxide (NH4OH) etc.
NaOH
Sodium hydroxide (NaOH) is also called caustic soda. It is available in solution at different concentrations or in solid form. Commercial NaOH often contains a little sodium carbonate (Na2CO3) as a by-product of the manufacturing process. This small amount of Na2CO3 will usually not influence its use in textile wet processes.
Owing to its strong alkalinity, NaOH can react with CO2 in air easily. It can also absorb water very quickly.
Na2CO3
Sodium carbonate (Na2CO3) is also called soda ash. In textile wet processes, it is often available in anhydrous form. Its purity can be > 99% Na2CO3 (58% Na2O).
If the concentration of a Na2CO3 solution needs to be determined, a titrimetric method identical to the ones listed for NaOH in this section can be used. If the existence of bicarbonate is a concern (very rarely in textile wet processes) the following method can be used to determine the content of bicarbonate in sodium carbonate.
NH4OH
Ammonium hydroxide (NH4OH) is a water solution of ammonia gas (NH3). It can also be called aqua ammonia or ammonia water. The concentration determination can be done using either a hydrometer or an acid–base titration. Since ammonia is volatile, the concentration determination should be done with care to avoid any loss of strength. If a hydrometer is used, the sample and the hydrometer should be cooled to 5–10 ºC. Table 4.75 lists the relationship between the concentration (% w/w) and ºBé of NH4OH at 10 ºC. Acid–base titration can also be used to determine the concentration of NH4OH.
