LAB EXPERIMENT 05

REMOVAL OF NATURAL AND ADDED IMPURTIES (SCOURIN) BY EXHAUST METHOD

PERFORMANCE ABJECTIVE

Upon the successful completion of this experiment student will be able to(i) Understand the mechanism of scouring and cotton of auxiliaries used(ii) Understand the exhaust method of scouring

MACHINES/MATERIAL REQUIRED

Desized fabric HT dyeing or Oscillating Dyeing machines

CHEMICAL REQUIRED

Caustic soda Wetting agent Sequesting agent

DISCUSSION

Natural cellulosic fiber like cotton and flax contain natural impurities like pectin’s, lignin, waxes and fats along with some added impurities such as oil stains, dirt and dust particle etc. Amount of these impurities present in different varieties of cotton and flax are given in the table below

Scouring is the process in which impurities present in the cellulosic fibers are removed by treating it with alkali. In the process fats, waxes, proteins, oils, pectin’s, ash miscellaneous

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Student Name: ___________________________________ ID No. ____________________

Signature of the lab tutor________________________ Date: _____________________

substance such as pigments amid cellulose and reducing sugure etc are removed from the fabric. The typical process consists of boiling the fabric with 3 to 6 % solution of sodium hydroxide (NaOH). Fats and waxes are insoluble in water, when alkali (NaOH) reats with them, soap is formed .This process is called saponification.

TRIGLYCERIDES:

This soap is not only water soluble but also has detergent properties. This will need to removal of the dirt impurities.During scouring of the natural cellulosic fiber, 5 to 10n % of the weight are lost as a result of removal of impurities. This weight loose is because of the degradation and the solution of the impurities like fats, waxes, proteins, pectin’s and lignin etc. however wettability and absorbency of the substrate is increased.

TYPICALL RECIPE

CHEMICAL QUANTITY

Liquir ratio 1:2

Caustic soda 1.0 – 2.0 %

SANDOPAN dtc (PASTE) 0.25- 0.5 G/L

Sirrix AK (liquid) 0.5 – 2.0 g/l

PROCEDURE

1. Prepare the bath according to the recipe 2. Start the process at 40 C 3. Treat the fabric at 100 C for 30 – 60 min 4. Finely hot rinse the fabric at 80 – 90 for 10 – 15 min 5. Cold rinse

CALCULATION

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S.NO MATERIAL QUANTITY

1 Fabric weight

2 Total liquir

3 Caustic soda

4 Sirrix AK

5 Sandopan DTC

Solomatic bleaching serves to remove almost all of the impurities including fats, waxes, proteins, pectin, ash, chlorophylls and xanthophyll’s and also seed fragments. Thus it is an economical process saving both the time and the money. However, if full if full white fabric with high degree of whiteness is intended then, it is better to perform both the process separately to achieved best results.

Typical Recipe

Chemical Quantities

Liquor 1:20

Caustic Soda 1.0%

Hydrogen per oxide .20 – 3.0 %

Stabilizer Y2K .025 – 0.5 %

Sandoclean PC-LF (paste) 0.5 – 1.0 %

Sirrix 2UD 1.0 %

REVIEW QUESTIONS

1. Describe soap formation while scouring of cotton fabric?

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2. Explain the roll of emulsifier in scouring?

3. How a NaOH solubilizes fats and waxes?

FINAL CHECK LIST

1. Clean your machinery equipment/materials and workbench before you leave.

2. Ensure the replacement of all equipment’s to their specified storage area.

3. Submit your answers to questions together with your data, calculation and result before the next laboratory/ equipment.

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