Methylene blue-grafted polyurethane foam using as a chelating resin for preconcentration and separation of cadmium(II), mercury(II), and silver(I) from waste water

Methylene blue (Me.B), 3,7-Bisdimethylamino-phenothiazine-5-chloride, is called basic dye, one of the basic dyestuff that has found considerable application in the extraction of anions and anionic complexes. The synthesis of methylene blue grafted foam is performed by coupling between polyether (polyols), methylene blue (Me.B), and toluene diisocyanate (TDI). Ion association complexes are formed between Me. B-grafted foam and cadmium(II), silver(I), and mercury(II) thiocyanate complexes. Me.B-grafted foam is used for preconcentration of Cd(II), Hg(II), and Ag(I) from waste water. Various conditions (pH, shaking time, maximum capacities, and chromatographic behavior) are studied. Cd(II) is separated at pH 1-4, while Hg(II) and Ag(I) at pH 1-2. Generally equilibrium extraction is obtained within a period from 15 to 20 min.