Oriented Membrane Processes for Selective Separation and Recovery of Direct Red 80 and Methylene Blue Dyes from Textile Wastewater

The objective of the present study was to develop an original polymer inclusion membrane with an extractive agent. For the elaborated membrane, FTIR spectra indicated the inclusion of the extractive agent, while SEM micrographs allowed characterizing the morphology and the porosity. After grafting Direct Red 80 dye molecules on the membrane surface, tests under our conditions indicated that the membrane became impermeable for the grafted dye. Such treated membrane was used to carry oriented processes for the treatment of aqueous discharges loaded with methylene blue (MB) and Direct Red 80 (DR 80) dyes, in order to recover these two dyes widely used in dyeing operations. Oriented processes for methylene blue substrate extraction from mixtures were carried out. The results showed the possibility to quantify processes by determining several parameters, permeability (P) and initial flux (J₀) relative to the membrane performance, apparent diffusion coefficient (D*) and association constant (K_ass), relative to the interaction of the substrate (S) with the extractive agent (T) forming entities (ST) during the diffusion of the substrate through the membrane phase. Several studies on the influence of initial concentration, acidity and temperature factors, on the evolution of J₀, P, K_ass, and D* parameters were carried out and the activation parameters (E_a, ΔH^≠ and ΔS^≠) have been determined. The results indicated that temperature strongly influenced the evolution for almost all the parameters as well as the membrane performance. Further, the results showed that the original membrane pretreatment allowed total and selective separation of dye mixtures (MB/DR 80).