REMOVAL OF ORGANIC-DYE (DIRECT BLUE) FROM SYNTHETIC WASTE-WATER BY ADSORPTIVE BUBBLE SEPARATION TECHNIQUES

C.I. Direct Blue 1, an anionic dye, was removed from synthetic wastewater by ion flotation of Direct Blue-hexadecyltrimethylammonium complex. Over 98% of Direct Blue was removed from the solution in 5 min. A stoichiometric amount of surfactant was found to be most effective for Direct Blue removal. The separation efficiency increased with increasing rate of air flow and decreased with increasing concentration of NaNO3. The efficiency of separation of Direct Blue by solvent sublation is similar to that by ion flotation. Direct Blue was also removed by adsorbing colloid flotation with Fe(OH)3 floc. Sodium lauryl sulfate was used as the collector and frother, and 99.8% of Direct Blue was removed in 3 min. The separation efficiency decreased with increasing ionic strength of the solution. Use of Al(III) ion as activator compensates somewhat for the deleterious effect of neutral salt on the adsorbing colloid flotation of Direct Blue. Both ion flotation and adsorbing colloid flotation may find application in the removal of organic dye from wastewater.