Adsorptive Removal of Methylene Blue from Simulated Dyeing Wastewater with Melamine-Formaldehyde-Urea Resin

A melamine-formaldehyde-urea (MFU) resin was used as adsorbent to clean wastewater containing a basic dye (methylene blue) used to simulate leather and textile processing dyes. Dye removal was followed by measuring the initial and final dye concentration in solution by UV-Vis spectroscopy using the analytical wavelength of lambda = 665 nm and the molar absorptivity of epsilon = (8.43 +/- 0.05) x 10(4) L mol(-1) cm(-1). The concentration range of methylene blue in solution for adsorption experiments was between 10(-7) and 10(-5) M so as to avoid dye polymerization reactions in solution that would give rise to apparent deviations from Beer's law. Batch and column methods were used for investigating adsorptive removal of dye. Parameters such as pH and contact time were optimized. The capacity of the sorbent for the dye was found by classical adsorption modeling (15.0 mg g(-1)) with the aid of a Langmuir isotherm. The optimal pH for adsorption was 7-8. Adsorption is thought to proceed mainly through cation exchange of methylene blue (MB+) with the R-COO (-) exchange groups of the sorbent. Adsorption was fast, and reached an equilibrium within 30 min. Color removal of simulated leather dyeing wastewater was shown to be feasible under optimal conditions. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 3442-3448, 2009