2.4.2. Dye application to materials
One gram of the dye powder was dissolved in 100 ml of
warmwater in order to prepare a 1%stock solution of the dye.
Each of the materials, sawdust and groundnut shells, 100 g
was added to 4 l of the diluted solution (material to liquor ratio
1:40) containing 50 ml of the stock solution of the dye liquor.
The dyeing reaction was started at 40 ◦C and the temperature
was slowly raised to 85 ◦C. After about 10 min, 65 g/l
of sodium sulphate deca hydrate was added in two lots in
10 min for improving the dye exhaustion onto the material.
After another 20 min, for covalent fixation of the dye onto
the material, 15 g/l of sodium carbonate was added to the
same bath and the treatment continued at 85 ◦C for further
30 min. In the end, the material was filtered, washed thoroughly
with hot water and then with cold water. The material
was then dried in an oven at 50 ◦C overnight and used as
adsorbent.