To study the factors affecting rate of filtration

Описание: To study the factors affecting rate of filtration

Apparatus: funnels, suction flask, rubber cork, beaker, measuring cylinder, mortar, pestle, spatula, glass rod, filter paper etc.
Chemicals: Calcium carbonate, glycerine, water etc.
Theory:
Filtration: It is the process of separation of solid from slurry by passing through porous medium that retain solids, but allows the liquid to pass through.
Terminology frequently used in filtration process:
Slurry: A suspension to be filter is called slurry.
Filter medium: a Medium use to separate solid from slurry.
Filtrate:The fluid that passes through a medium is called the filtrate.
Filter cake: A solid that retain on filter medium due to filtration.

Process of filtration:
When slurry is placed over the filter medium liquid flow through medium due to pressure difference across the medium and gradually solid retain on filter medium which in turn increases filter cake height. This increasing height of filter cake offers resistant to flow of liquid so that to continue filtration need higher pressure to be applied above filter medium called positive pressure or by applying suction below filter medium called negative pressure.
Rate of filtration:
It is expressed as volume of filtrate (V) per unit time (dv/dt).
Factor affecting rate of filtration:
Driving forces for filtration:
1. Surface area (A): surface area of filter medium is directly proportional to rate of filtration
2. Pressure difference (ΔP):Pressure difference is directly proportional to rate of filtration.
3. Permeability constant of cake (K): Higher is the permeability of filter cake higher is the rate of filtration.
Resistance for filtration:
1. Viscosity of slurry solvent (η): It is inversely proportional to rate of filtration, ie. Increase in viscosity decreases rate of filtration.
2. Height of filter cake ( l):It is inversely proportional to rate of filtration,ie. Increase in height of filter cake decreases rate of filtration.
Result:
1. Rate of filtration increases with increase in surface area of filter medium.
2.Rate of filtration decreases with increase in height of filter cake ( l).
3.Rate of filtration decreases with increase in viscosity of disperse medium of slurry.