Foam separation for effective removal of disperse and reactive dyes from aqueous solutions

In this study, the effectiveness of the foam separation process for removal of color and total organic carbon (TOC) from the dye solution was assessed. The optimum experimental conditions for the selected parameters such as pH, air flowrate, concentration of surfactant etc. were determined for RR 241 and DB 60, and the performance difference of the foam separation process for water-soluble and insoluble dyes has been demonstrated. The optimum conditions were determined as pH 5 and pH 3 with surfactant concentration of 100 mg-L-1 and at air flowrate of 0.5 and 0.2 L-min(-1) for the treatment of 500 mL of 100 mg-L-1 RR 241 and DB 60 solutions, respectively. At these optimum conditions, 99.6 - 92.4% color and 92.5 - 85.6% TOC removals were reached for RR 241 and DB 60, respectively. In the case of nitrogen gas bubbled into the column instead of air under the same optimum conditions, color and TOC abatements were 99.1 - 99.4% and 91.1 - 84.8% for RR 241 and DB 60, respectively. In the nitrogen gas assays, the experiments were performed under the same conditions with air as pH 5 and pH 3 with surfactant concentration of 100 mg-L-1 and at gas flowrate of 0.5 and 0.2 L-min(-1) for the treatment of 500 mL of 100 mg-L-1 RR 241 and DB 60 solutions, respectively. According to the results, the treatment performance of foam separation process depends strongly on the structure of pollutant and type of the carrier gas used in the column.