REMOVAL OF DIRECT-RED FROM AQUEOUS-SOLUTION BY FOAM SEPARATION TECHNIQUES OF ION AND ADSORBING COLLOID FLOTATION

Experimental investigations on the removal of Direct Red from an aqueo us solution were carried out through two foam separation techniques: i on flotation and adsorbing colloid flotation with Fe(III). The residua l concentration of Direct Red can be lowered to below 0.5 ppm in 3 min utes by ion flotation and below 0.1 ppm in 2 minutes by adsorbing coll oid flotation. The optimum pH for the removal of Direct Red was found to be 4 for ion flotation and 3-5 for adsorbing colloid flotation. The effects of surfactant, foreign ions, and Al(III) addition on the remo val of Direct Red are discussed.