Biosorption of methylene blue from aqueous solutions by microalgae Scenedesmus in the presence of sodium dodecyl sulfate

Synthetic dyes such as methylene blue (MB) are used in the variousfields such as dyeing textile industries. Effluents of these industries contain high amounts of dyes and surfactants, and their discharge into the water resources inhibits the photosynthetic action. Recently, researchers have focused the biosorption process as an effective and cheap method for the removal of synthetic dyes from wastewater. In this study, the capability of microalgae Scenedesmus in the removal of MB was examined at 30oC and pH values of 5, 7 and 9 in the absence and presence of a surfactant namely sodium dodecyl sulfate (SDS). In this regard, aqueous solutions of MB was prepared with different concentrations of MB and SDS. The pH of solutions was adjusted by NaOH and HCl solutions using a pH meter. Then, 0.02 g Scenedesmus was added to 20 cc solutions. The samples were agitated at 120 rpm and 30oC by a shaking incubator for five hours. Finally, the concentrations of MB were measured by using a spectrophotometer at 665 nm. Results showed that MB uptake increased with increasing pH. In addition, the presence of 0.25 g/lit SDS in the solutions resulted in 100% MB removal. While the MB sorption decreased significantly, where the concentration of SDS deviated from 0.25 g/lit.