## Construction of drying curves (for calcium carbonate and starch)

### AIM:

To determine the construction of the drying curve for calcium carbonate.

### REQUIREMENTS:

- Petri dish
- hot air oven
- calcium carbonate
- weighing balance
- spatula

### PRINCIPLE:

To behaviour of drying of solid is explained by the drying curve. The time required for drying a batch of the weight of martial in dry air can be estimated with the help of the drying curve.

Drying is a mass transfer process consisting of the removal of water or another solvent by evaporations from a solid, semisolid or liquid. This process is obtained and used as the final production step before, packing products.

### PROCEDURE:

- Take a clean Petri dish without a Lid and consider its weight as W1gm
- Note the area of the Petri dish
- Take 10gm calcium carbonate in a clean Petri dish and consider its weight as W2 gm
- Prepare slurry by adding water consider its weight as W3 gm
- Heat Petri dish in a hot air oven at a temperature of 70°C
- Note down the weight of the sample after every 15 minutes.
- Continue drying until there is no change in weight of the sample is obtained
- Determine percentage moisture content and drying rate by using the following formula

Percentage moisture = W3-W2/W3-W1 × 100

Drying content =W3-W2/area of Petri dish ×100

### REPORT:

- The construction of drying curves of calcium carbonate was determined
- The percentage moisture content is =

### Calculation:

- Weight of empty Petri dish (w1) gm =
- Weight of empty Petri dish + sample (w2) gm =
- Weight of empty petridish + sample + water (w3) gm = Weight of empty petridish + sample + water + (w4) gm = (After drying at different time interval)
- MC1 (moisture content at 0 time) =
- MC2 (moisture content at 15 minutes time) =
- Average moisture content =
- Rate of drying =

**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.