Efficient Dye Removal from Aqueous Solutions Using Rhamnolipid Biosurfactants by Foam Flotation

Abstract

<em>Methylene blue was efficiently removed from aqueous solution by foam flotation </em><em>using a rhamnolipid biosurfactant as a dye collector. The effects of four parameters, namely, pH (1.5–11.5),</em><em> frother concentration (5–65 ppm), aeration rate (2–6 L/min) and rhamnolipid to methylene blue weight ratio (0.5–6.5), on dye removal were studied and optimized using response surface methodology. Results showed that dye removal increases by increasing of all parameters; however, </em><em>the nonlinear trend was observed for the effects of frother concentration and rhamnolipid to methylene blue ratio. Optimum removal conditions, resulting in about 93% dye removal, was achieved</em><em>at pH value of 11.5, methyl isobutyl carbinol (MIBC) concentration of 35 ppm, airflow rate of 4 L/min, and rhamnolipid to methylene blue ratio of 3.5, after only 10 min flotation. Investigations also showed</em><em> that the presence of electrolyte can significantly decrease the removal efficiency. Kinetics study revealed that the process follows the first-order model with a rate constant of about 0.288 sec^-</em><em>This study demonstrates that rhamnolipid could be considered as a potentially efficient and environment-friendly collector for the treatment of dye contaminated wastewater.</em>