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

Tetrasulphonated copper (II) phthalocyanine (TCP), in the salt form, was in corporated into a blend of chitosan (CTS)/poly(vinylalcohol) (PVA) and micr ospheres were produced using the method of salt coacervation with (similar to 20% w/v) sodium sulphate. Spectroscopic analysis, DSC and TGA were carri ed 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 scannin g electronic microscopy (SEM). Microspheres coagulated in sodium sulphate a nd also in an alkaline salt medium (0.5 and 2.0 M NaOH) were exposed to a s olution of the dye, methylene blue, at an initial concentration of 7 mg/l a nd maintained in contact for 14 h at 26 +/- 1 degrees C. The kinetic data r evealed a decrease in the capacity of sorption of the microspheres that had received the alkaline treatment. It is proposed that the new morphology at tributed to these species blocks some sites for complex formation, mailing them inaccessible to the dye.