REMOVAL OF METHYL ORANGE AND METHYLENE BLUE DYE FROM WATER USING COLLOIDAL GAS APHRON—EFFECT OF PROCESSES PARAMETERS

Abstract

Colloidal gas aphron (CGA) was used in a flotation column to remove methyl orange and methylene blue dye from water. The effect of process parameters, i.e., surfactant type and concentration, CGA flow rate, CGA diameter and gas holdup, pH, residence time, and salt concentration, were studied through measurements of percent dye removal. The overall percent removal of methyl orange and methylene blue was 95–98% for the range of experimental parameters studied. When the surfactant and dye had a similar charge, 40% removal of dye from the water was achieved. This result was unexpected because dye removal by CGA was thought to be an ion-flotation process. However, the oppositely charged dye and surfactant resulted in 98% removal of dye. Based on these observations, the mechanism for dye removal from water using CGA was elucidated. The removal of methyl orange was higher in alkaline conditions when CGA was generated from the cationic surfactant, hexadecyltrimethyl ammonium bromide. The removal of methyl orange is higher in alkaline condition when generated from the anionic surfactant, sodium dodecylbenzene sulfonate. The percent removal of methyl orange and methylene blue increased with increased flow rate, decreased CGA diameter, and increased gas holdup. The percent removal of dyes increased with increased residence time of CGA in the flotation column. No effects of surfactant concentration above the cmc or salt concentration on the percent removal of dye were observed within the range of experimental parameters.