The exhausted permutit can be regenerated by percolating a

Options

A. 10% HCI solution
B. 10% `H_(2)SO_(4)` solution
C. 10% NaOH solution
D. 10% NaCl solution.

Answer

To solve the question regarding the regeneration of exhausted permutit, we can break down the process step by step.

### Step-by-Step Solution:

1. **Understanding Permutit**:
- Permutit, also known as sodium zeolite, is a chemical compound with the formula Na2Al2Si2O8·xH2O. It is used in water softening processes to remove hardness from water.

**Hint**: Remember that permutit is a sodium-based zeolite used for ion exchange.

2. **Formation of Exhausted Permutit**:
- When hard water, which contains calcium (Ca²⁺) and magnesium (Mg²⁺) ions, passes through permutit, these ions are exchanged with sodium ions (Na⁺) from the permutit.
- This process leads to the formation of exhausted permutit, which can be represented as Ca2Al2Si2O8·xH2O or Mg2Al2Si2O8·xH2O.

**Hint**: The ion exchange process is key to understanding how permutit becomes exhausted.

3. **Regeneration Process**:
- To regenerate exhausted permutit, a concentrated solution of brine (which is a solution of sodium chloride, NaCl) is used.
- The brine solution allows sodium ions to replace the calcium and magnesium ions that were absorbed by the permutit.

**Hint**: Focus on the role of brine in replacing the absorbed ions.

4. **Chemical Reaction**:
- The reaction during regeneration can be summarized as:
\[ \text{CaZ or MgZ} + 2 \text{NaCl} \rightarrow \text{Na2Z} + \text{CaCl2 or MgCl2} \]
- This shows that the exhausted permutit (CaZ or MgZ) reacts with sodium chloride to regenerate the permutit (Na2Z) and produces calcium chloride or magnesium chloride as by-products.

**Hint**: Keep in mind the stoichiometry of the reaction when considering the ions involved.

5. **Final Conclusion**:
- Therefore, the exhausted permutit can be regenerated by percolating a 10% NaCl solution (brine solution).

**Hint**: The answer to the question is directly linked to the regeneration method using NaCl.

### Final Answer:
The exhausted permutit can be regenerated by percolating a **10% NaCl solution**.