Microspheres of chitosan/poly(vinylalcohol) incorporating tetrasulphonated copper (II) phthalocyanine: preparation and characterization

Abstract

Tetrasulphonated copper (II) phthalocyanine (TCP), in the salt form, was incorporated into a blend of chitosan (CTS)/poly(vinylalcohol) (PVA) and microspheres were produced using the method of salt coacervation with (~20%w/v) sodium sulphate. Spectroscopic analysis, DSC and TGA were carried out to characterize the form in which the macro-complex was immobilized in the blend. Alkaline treatment of the coagulating medium produces species which are more stable, but with a different morphology observed by scanning electronic microscopy (SEM). Microspheres coagulated in sodium sulphate and also in an alkaline salt medium (0.5 and 2.0M NaOH) were exposed to a solution of the dye, methylene blue, at an initial concentration of 7mg/l and maintained in contact for 14h at 26 1oC. The kinetic data revealed a decrease in the capacity of sorption of the microspheres that had received the alkaline treatment. It is proposed that the new morphology attributed to these species blocks some sites for complex formation, making them inaccessible to the dye.