Di-Octyl Amine Mediated Transport of Lignosulfonate using Bulk Liquid Membrane Technique

Abstract

Although there are several techniques in vogue to separate organic/inorganic components from contaminated waste water emanating from many sources, liquid membrane techniques have been gaining much attention and acceptability in the research arena owing to their simplicity in operability, high removal efficiency and superior selectivity during the transport process. It is also important to highlight the fact that selecting a carrier suitable for specific applications using liquid membranes is a tedious proposition and it requires a calibrated approach to figure out the suitable one. We proposed a simple bulk liquid membrane (BLM) technique to separate lignosulfonate from its model contaminant. The source phase was an aqueous solution sodium lignosulfonate and the strip phase was NaOH solution. 1, 2-dichloroethane was selected as solvent in the liquid membrane phase. Di-octyl amine was chosen as the carrier for this study primarily due to its amine functionality. A comprehensive 2-phase equilibrium study was followed by 3-phase kinetic study to ascertain and establish various parameters for this unit operation. Effect of manifold parameters like carrier volume %, pH of feed phase, strip and feed phase concentration were studied to find out optimum working conditions. In this BLM ensemble, an extraction lignosulfonate of ca. 98% was achieved from source phase to membrane phase whereas the recovery from membrane phase to strip phase was ca. 75%. The optimum strip phase concentration was found to be 0.5 N and the optimum carrier concentration was 3 vol%. Acidic condition was found to be favouring the transport process where the optimum pH of the feed phase was found to be 2. Finally, the transport mechanism was seen to highly influenced by the stirring conditions and the best results were obtained when all the three phases were stirred simulateously. Membrane reusability study also categorically showed consistent performance during multi-fold use.