February 22, 2024

# Factors affecting Rate of Filtration and Evaporation (Surface area, Concentration and Thickness/ viscosity)

## To study the effect of various factors on the rate of filtration.

### Apparatus:

Beaker
Filter paper
Measuring cylinder

### Principle:

Filtration is a process of where by solid particles present in a suspension are separated from the liquid or gas employing a porous medium. Which retains the solid but allows the fluid to pass through the volume of the filtrate obtained through the filter paper per unit time is called “rate of filtration” can be given by mathematical equation.
dv/dt = K.A . ⌂P/µL – darcy’s law

where,
A = area of filter
⌂P = pressure drop across the filter medium and cake
µ = viscosity of filtrate L = thickness of cake
V = volume of the filtrate T = time taken for filtration
K = constant for the filter medium and filter cake or resistance

### Procedure:

a) Effect of thickness of cake:

Prepare two solutions of calcium carbonate using water as the solvent the concentration of the solutions are 5% and 10% respectively. Filter them and note the time taken for filtration to calculate the rate of filtration and compare them.

b) Effect of viscosity:

Effect of viscosity causing two solutions one with water and other with mixture of glycerine and water (20:80) ratio respectively. Prepare two different solutions of 5% calcium carbonate (CaCo3) using above prepared water and glycerine mixture. Filter them and note the time for filtration to calculate the rate of filtration and compare them.

c) Effect of area:

This can be determined by using funnel of large (big) and small area for the same concentration of the solutions (5% CaCo3) time taken for filtrations are noted. Calculate the rate of filtration and compare them.

d) Effect of pressure:

Prepare two solutions of calcium carbonate (5% CaCo3) using water as a solvent filter one of the solutions through Buchner funnel. Which is connected to a suction pump and the other one is filtered through without suction pump and note the time taken for filtrate. Calculate the rate of filtration and compare them

### Calculation:

Effect of thickness of cake:

Sample: 50 ml of 5% CaCo3

50 ml of 10% CaCo3

Effect of viscosity:

Sample: 50 ml of 5% CaCo3
50 ml of 10% CaCo3 (Glycerine and water mixture 20:80)

Effect of an area of the funnel:

Sample: 50 ml of 5% CaCo3

Effect of pressure:

Sample: 50 ml of 5% CaCo3 (glycerine water mixture 20:80)

### Report:

Rate of filtration in thickness

5% caco3 =
10% caco3 =

Rate of filtration in viscosity

5% caco3 =
5% caco3 with glycerine = Water mixture

Rate of filtration in area

5% caco3 in small funnel = 5% caco3 in big funnel =

Rate of filtration in pressure

5% caco3 with pressure = 5% caco3 without pressure =

AIM:

## To study the effect of various factors on the rate of evaporation.

### Principle:

Evaporationis the process by which liquid water goes directly to the vapour phase due to an increase in temperature. The main objective of evaporation is to get a concentrated product by vaporizing volatile liquid.Evaporation is conducted by non-volatile solute and volatile solvent to produce thick liquor. Rate of evaporation is controlled by rate of heat transfer.
Objectives of evaporation:

Evaporation is done by following,

 To get a concentrated product
 To remove water from an aqueous solution
 To evaporate sea water for developing drinking water
 To get solid from water which is used in boiler for chemical process

### Factors influencing evaporation:

1. Temperature
The evaporation rate is directly related to the temperature. As the temperature increases, the rate of evaporation also increases because the temperature is rising the water molecules begin to move faster.
2. Surface area
The rate of evaporation is directly proportional to the surface area of the vessel exposed to evaporation.
3. Agitation
Agitation is necessary for evaporation.
4. Vapour pressure
Liquids with a low boiling point evaporate quickly due to high vapour pressure.
5. Types of products required
The selection of the method and apparatus to be used for evaporation depends upon the type of product required for example open pan produce liquid or dry concentrate while a film evaporator yield liquid concentrates.
6. Density
As the density increases, the rate of evaporation decreases.
7. Time of evaporation
Exposure to a relatively high temperature for a short time may be less destructive to the active ingredients than a lower temperature with exposure for a longer period.
8. Economic factors
When selecting the method and apparatus the economic factors are important. Evaporators are designed to give maximum heat transfer to liquid.
9. Moisture content
Some drug constituents decompose more rapidly in the presence of moisture, especially at raised temperatures.

## Effect of surface area on the rate of evaporation:

### Requirements:

 Three Petri dishes of diameter 2.50 cm, 5 cm, 7.5 cm with cover, 10 ml of the pipette and stopwatch

### Procedure:

 Clean and dry all Petri plates and mark them as A, B, and C.
 Pipette out of 10 ml diethyl ether in each of the Petri dishes A, B, and C and cover them immediately.
 All the Petri dish heated in water at constant temperature for 10 minutes

 Note the remaining volume after 10 minutes
 From the rate of evaporation is calculated Effect of viscosity on the rate of evaporation: Requirements:
 Glycerine, distilled water, beaker, measuring cylinder.

### Procedure:

 Different concentrations of glycerine and water are prepared in different beakers.
Note the weight of the beaker containing glycerine- water mixture.
 All the beakers are heated in water at a constant temperature for 10 minutes.
 Again note the weight of the beakers after heating.
 The difference between the weights is measured. The difference indicated the amount of water evaporated for 10 minutes.
 The rate of evaporation is calculated

## Effect of concentration on the rate of evaporation:

### Procedure:

 Clean all the glassware
 Prepare different concentration (2%, 4%, 6%, 8%) solution of sodium chloride in 50 ml water in different beakers
 Weigh of the beaker containing sodium chloride solution
 All the beakers are heated in water at constant temperature for 10 minutes
 Again weigh the beakers after heating
 The difference between weights is measured. The difference indicated the amount of water evaporated during 10 minutes
 From this rate of evaporation is calculated.

Effect of Surface area

Effect of Viscosity

Effect of Concentration

Pharm Engg Chapterwise MCQ: UNIT-I MCQ * Flow of fluids * Size reduction * Size separation UNIT-II MCQ *Heat transfer *Distillation *Evaporation UNIT-III MCQ *Drying * Mixing UNIT-IV MCQ * Filtration * Centrifugation * UNIT-V MCQ Materials of construction * Corrosion