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

Pharmaceutical Engineering Practical Lab Manual PDF Download

## 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

Sample | Time Taken For Filtration | Volume of Filtrate | Rate of Filtration |

5% CaCo3 | 5 minutes (300 seconds) | 34 ml | 34/300 = 0.1134 ml/sec |

10% CaCo3 | 7 minutes (420 seconds) | 40 ml | 40/420 = 0.0952 ml/sec |

**Effect of viscosity:**

Sample: 50 ml of 5% CaCo3

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

Sample | Time Taken For Filtration | Volume of Filtrate | Rate of Filtration |

5% CaCo3 | 8 minutes (480 seconds) | 35 ml | 35/480 = 0.0729 ml/sec |

5% CaCo3 with glycerin and water mixture | 6 minutes (360 seconds) | 44 ml | 44/360= 0.1222 ml/sec |

**Effect of an area of the** **funnel:**

Sample: 50 ml of 5% CaCo3

Sample | Time Taken For Filtration | Volume of Filtrate | Rate of Filtration |

5% CaCo3 filter in small funnel | 7 minutes | 42 ml | 0.1 ml/sec |

10% CaCo3 filter in big funnel | 7 minutes | 40 ml | 0.09 ml/ sec |

**Effect of pressure:**

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

Sample | Time Taken For Filtration | Volume of Filtrate | Rate of Filtration |

5% CaCo3 filter with pressure | 36 seconds | 46 ml | 1.27 ml/sec |

10% CaCo3 filter without pressure | 6 minutes | 42 ml | 0.116 ml/ sec |

### 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:

- 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. - Surface area

The rate of evaporation is directly proportional to the surface area of the vessel exposed to evaporation. - Agitation

Agitation is necessary for evaporation. - Vapour pressure

Liquids with a low boiling point evaporate quickly due to high vapour pressure. - 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. - Density

As the density increases, the rate of evaporation decreases. - 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. - Economic factors

When selecting the method and apparatus the economic factors are important. Evaporators are designed to give maximum heat transfer to liquid. - 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**

Petridish Marked | Diameter of Petridish | Volume Taken | Remaining Volume | The Volume of Liquid Evaporated | Rate of Evaporation (ml/sec) |

A | 2.5 | 10 ml | |||

B | 5 | 10 ml | |||

C | 7.5 | 10 ml |

**Effect of Viscosity**

Glycerin (ml) | Water (ml) | Concentration % V/V | Initial Weight of Solution (g) | Final Weight (g) | Weight of Water Evaporated | Rate of Evaporation g/sec |

2 | 5 | 2% | ||||

4 | 10 | 4% | ||||

6 | 15 | 6% | ||||

8 | 20 | 8% | ||||

10 | 25 | 10% |

**Effect of Concentration**

Concentration % W/V | Initial Weight of Solution (g) | Final Weight of Solution (g) | Weight of Water Evaporated | Time of Heating | Rate of Evaporation (g/sec) |

2% | 20 | ||||

4% | 20 | ||||

6% | 20 | ||||

8% | 20 |

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

Pharmaceutical Engineering Practical Lab Manual PDF Download

I. Determination of radiation constant of brass, iron, unpainted and painted glass.

II. Steam distillation – To calculate the efficiency of steam distillation.

III. To determine the overall heat transfer coefficient by the heat exchanger.

IV. Construction of drying curves (for calcium carbonate and starch).

V. Determination of moisture content and loss on drying.

VI. Determination of humidity of the air – i) From wet and dry bulb temperatures –use of Dew point method.

VII. Description of Construction working and application of Pharmaceutical Machinery such as rotary tablet machine, fluidized bed coater, fluid energy mill, dehumidifier.

VIII. Size analysis by sieving – To evaluate size distribution of tablet granulations – Construction of various size frequency curves including arithmetic and logarithmic probability plots.

IX. Size reduction: To verify the laws of size reduction using a ball mill and determining Kicks, Rittinger’s, Bond’s coefficients, power requirement and critical speed of Ball Mill.

X. Demonstration of colloid mill, planetary mixer, fluidized bed dryer, freeze dryer and such other major equipment.

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

XII. To study the effect of time on the Rate of Crystallization.

XIII. To calculate the uniformity Index for a given sample by using Double Cone Blender.

**Second Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise**

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