Partition study of textile dye Remazol Yellow Gold RNL in aqueous two-phase systems

• Sustainable methods for the removal of Remazol Yellow Gold RNL are in demand.
• Partition studies in aqueous two-phase systems were carried out.
• Biphasic systems employing salts with polymers or ionic liquids were evaluated.
• The optimized system gave satisfactory dye partition coefficients (KYR).
• Removal of Remazol Yellow Gold RNL from real wastewater was achieved.

The removal of organic dye pollutants from wastewater produced by the textile industry is a complex problem that presents potential health risks to the general public. Remazol Yellow Gold RNL (YR) dye is readily used to dye cellulose base materials and the methods developed for its removal from aqueous systems are either inefficient or too expensive to be adopted by smaller textile manufactures. Our approach is based on aqueous two-phase system (ATPS) using salts and either polymers or ionic liquids to extract Remazol Yellow Gold RNL from wastewater. Parameters such as the nature of the electrolyte, molecular mass of polymer and tie line length (TLL) on the dye partition coefficient (KYR) were all evaluated. A phase diagram for the polyethylene glycol (PEG 4000 g mol−1) and magnesiumsulfate system at 298.15 K was obtained and used to study the partitioning of YR. The KYR values demonstrate the potential of both systems for the removal of dyes from industrial effluents. The partition mechanism was discussed based on the Haynes model and using the of Gibbs standard energy change (ΔtrG°). The driving force (enthalpy and/or entropy) that governs the partitioning of the dye depends on the nature of the ATPS. The optimized conditions that gave the best system was successfully applied to the removal of YR from wastewater obtained from a local textile manufacturer. The high KYR values in the presence of the effluent demonstrate the potential and robustness of the ATPS for the treatment of effluents from textile industries.