Hardness Of Water Flashcards
What is desalination?
It is a process in which removal of dissolved salts occurs.
What is desalination of Brackish water called?
Reverse osmosis.
How the hardness of water in reverse osmosis is removed?
The hardness of water in reverse osmosis is removed with the help of RO CELL.
METHOD:An external pressure of 280 to 800 psi is applied to the piston of the RO CELL in which brackish water is present .The dissolved salts or minerals from brackish water,i.e.,the hardness of water is removed when it flows from high concentration to low concentration and passes through the semipermeable membrane made of polymeric material (Eg-polyamides, aromides,etc)and hence gets converted to potable water or drinking water which passes through the outlet and collected.
Explain the zeolite process used for softening of hard water.
When Ca^2+ and Mg^2+ ions containing hard water passes through a bed of NA2Ze , the Na^+ ions are replaced by Ca^2+ and Mg^2+ ions .When all the Na^+ ions are replaced by Ca ^2+ and Mg^2+ ions , the zeolite becomes inactive. Then the zeolite needs to be regenerated. Brine solution are passing through the bed of reactivated zeolite.The following r*n takes place and form Na2Ze:
CaZe +2NaCl→Na2Ze+CaCl2
MgZe + 2NaCl→Na2Ze+MgCl2
The softening of water by this process is used for laundry purpose and cannot be used for boiler purpose. B/c this water softening contains NaHCO3 in the water. When this water is heated,it produces CO2 which is corrosive for boiler plates.
Na2Ze + Mg(HCO3)2→2NaHCO3+MgZe
State the advantages of zeolite process.
1.It is quite clean.
2.It requires less time for softening.
3.It requires less skill for maintenance as well as operation.
4.The equipment used is compact, occupying a small space.
What do you mean by Zeolite?
Zeolite is a microporous mineral which is used as a catalyst in many industrial purposes such as water purification and air purification .
It is a mineral (of green sand colour).
The chemical structure of sodium zeolite may be represented as:
[Na2O.Al2O.xSiO2.yH2O]
x=2-10
y=2-6
Distinguish between temporary and permanent hardness.
Temporary Hardness: Hardness due to the presence of bicarbonates of calcium and magnesium is called temporary hardness or carbonate hardness.This is also known as alkaline hardness.This hardness can be removed by mere boiling of water, which converts the bicarbonates into insoluble carbonates of hydroxides. The insoluble carbonates or hydroxides can be removed by filtration.
MgCO3 +H20→Mg(OH)2↓+CO2
Ca(HCO3)2→CaCO3↓+H20+CO2
Permanent Hardness: Hardness due to the presence of sulphonates and chloride of calcium and magnesium.This is also known as non carbonate hardness. Permanent hardness cannot be removed by boiling.Special method is used for removal of permanent hardness.
We can remove this hardness by treating the water with washing soda.Insoluble carbonates are formed when washing soda reacts with the sulphide chloride salts of magnesium and calcium and thus hard water is converted to soft water.
Short note on boiler troubles.
Refer your notes
What is hardness of water?
The term was applied to the waters which makes cleansing action of soap difficult.
State the cause of hardness.
Notes!!
What are ion exchange resins.
How will you purify water using resins?
Explain proximate analysis.
What is biogas?
Discuss the mechanism of biogasification.
