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 nonvolatile 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: UNITI MCQ * Flow of fluids * Size reduction * Size separation UNITII MCQ *Heat transfer *Distillation *Evaporation UNITIII MCQ *Drying * Mixing UNITIV MCQ * Filtration * Centrifugation * UNITV 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.
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