OBA Removal:
A simple OBA stripping technique given below can be adopted in jiggers very efficiently and you can strip off almost 98% of OBA.
Recipe and method of process flow given below may be used as new hint..
a) Wetting the fabric:
Soap - 1 gm/liter, Soda ash 1 gm/liter - treat the fabric at 70°C for 30 minutes.
b) Oxidative Bleaching:
Potassium Permanganate (KMnO4) - 0.5% wof at cold for 30 minutes - to the same bath add Hydrochloric acid (35% conc.), 3 times the quantity of KMnO4 continue run for another 30 minutes. Then raise the temperature to 50°C and run for 30 minutes.
Drain the bath - cold wash - 30 minutes.
c) Reductive Bleaching:
Run 10 minutes with Caustic soda 5 gms/liter and then add 5 gms/liter of Hydros (Sodium Hydro Sulphite) at room temperature and run for 10 minutes. Then slowly raise the temperature to 60°C. During this process the brown coloration you have got would be converted to light beige like shade. Now do one thorough cold wash.
4) Oxalic Acid Treatment:
Treat with 2 gms/liter of Oxalic acid at room temperature for 30 minutes or 2 ends followed by a cold wash.
5) Soda ash Neutralization:
Treat with 2 gms/liter of soda ash at room temperature for 30 minutes and again do a cold wash.
6) Acetic acid Neutralization:
Treat the fabric with 1 gm/liter of acetic acid for 10 minutes at cold. Check the pH and let it be 6.
Now you will wonder to see thorough removal of OBA.
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