Question asked by Filo student

process is called cold lime-soda method and if in hot water the process is called the hot lime-soda method.

1. 4.6.2 Permutit Process (or Zeolite Process)
2. :This is modern process used for removing both temporary and permanent hardness of water. Permutit is a synthetic resin while zeolite is a naturally occuring mineral which are complex silicates of several metallic and non-metallic oxides. They have approximate composition ${\mathrm{Na}}_2{\mathrm{Al}}_2{\mathrm{Si}}_2{\mathrm{O}}_8,6{\mathrm{H}}_2\mathrm{O}$ which is a mixed oxide $\left[{\mathrm{Na}}_2\mathrm{O},{\mathrm{Al}}_2{\mathrm{O}}_3,2{\mathrm{SiO}}_2,6{\mathrm{H}}_2\mathrm{O}\right]$. These silicates hold sodium ions lossly, hence these are called as sodium permutit $\left({\mathrm{Na}}_2\mathrm{P}\right)$ or sodium zeolite $\left({\mathrm{Na}}_2\mathrm{Z}\right)$.
3. The remarkable property of sodium permutit $\left({\mathrm{Na}}_2\mathrm{P}\right)$ is that when it comes in contact with hard water, it exchanges its ${\mathrm{Na}}^{+}$ions with ${\mathrm{Ca}}^{++}$ and ${\mathrm{Mg}}^{++}$ions to form insoluble calcium permutit (CaP) or magnesium permutit (MgP).
4. Sodium permutit is placed in a suitable container and hard water is allowed to pass through it (Fig. 4.2). The calcium and magnesium salts react with it forming insoluble calcium and magnesium permutits. These salts are ratained on the filter bed and water after reaction is therefore free from ${\mathrm{Ca}}^{++}$and ${\mathrm{Mg}}^{++}$ions. Only the harmless sodium salts are left in water. The following reactons takes place in the process.

Views: 5,258 students

Updated on: Apr 19, 2023