Removal of Colored Wastewater Generated From Hand-Made Textile
The hand-made textile weaving industry in Thailand produces only a small volume of colored wastewater. These small industries, however, are scattered throughout the country, crating widespread water resources contamination. For local villagers, conventional treatment technologies are too costly to bear and too complicated to handle. Consequently, villagers simply pay no attention to the treatment of their wastewater products.
A study of the decolorization of cotton direct dyestuffs (Blue 201, Red 23 and Violet 9) by wood charcoal (WC) and activated wood charcoal (AWC) is presented. Studies of the effects of pH, contact time, salt concentration and temperature on the absorption were conducted. Equilibrium absorption capacity was studied using Langmuir and Freundlich isotherms.
The absorption of direct dyestuffs on both WC and AWC was found to conform to the two isotherms. The absorption of Red 23 and Violet 9 on AWC is pH independent over a pH range of 4.5 to 11.0, but the absorption of Blue 201 is slightly increased at a lower pH. The concentration of NaCl up to 10,000 ppm has no effect on the absorption of all dyes. Temperature has very little effect on the absorption of Blue 201, but the binding of Red 23 and Violet 9 is higher at a higher temperature, which indicated the endothermic absorption reaction. The absorption capacity of Blue 201, Red 23 and Violet 9 by AWC is about 2.3, 1.2 and 1.2 times higher than by WC.
WC, even though it is less effective than AWC, is an effective and inexpensive absorbent for the absorption of direct dyestuffs. The treatment method (absorption) is easy to handle and requires no special skills for a person to operate and to maintain. The cheap WC makes regeneration not necessary and it could be burnt.
Winai Somboon is associated with Department of Chemistry, Faculty of Science, King Mongkuts University of Technology Thonburi, Bangkok,Thailand.