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Re ceived: Oc to ber 15, 1996; Au gust 2, 1996 Mostramos neste trabalho alguns detalhes sobre a imobilização de complexos ferrocianeto e ferricianeto sobre a superfície do biopolímero quitosana. Os complexos imobilizados foram caracterizados por eletroquimica, espectrocopia de infravermelho e Mössbauer. Foi observado mudanças nos espectros de infravermelho e Mössbauer, e no voltamogramas cíclicos do ma terial preparado com ferricianeto após exposição a luz do sol. Estas alterações indicam que o ferricianeto sofreu um processo de redução fotoinduzida na superfícies do biopolímero.We re port some de tails of the ferro cyanide and ferri cyanide com plexes im mo bi lized in chitosan. These im mo bi lized com plexes are char ac ter ized by elec tro chem is try, and in fra red and Mössbauer spec tros copy. Al ter ations are ob served in the in fra red and Mössbauer spec tra and in the cy clic voltammograms of the ma te rial pre pared with ferri cyanide when this ma te ria l is ir ra di ated with sun light. These al ter ations in di cate that the ferri cyanide ion un der g oes a photoinductive re duc tion on the biopolymeric sur face. Key words: chitosan, cy clic voltammograms, photoinductive re duc tion In tro duc tionIn re cent years in creased at ten tion has been given to sun light-induced pho to chem i cal ef fects. The photoreactivity of both or ganic and in or ganic iron complexes has been rec og nized for a long time, and many reports on the ef fects of light on the chem is try of iron have been pub lished over the last 100 years 1 . In this study the prep a ra tion and char ac ter iza tion of ferro cyanide and ferricyanide com plexes im mo bi lized in chitosan is de scribed. Chitosan is a polysaccharide usu ally pre pared by the N-desacetylation of chitin, through a ba sic hy dro ly sis re action, and largely con sists of glucosamine units and a smaller per cent age of N-acetyl-glucosamine res i dues ( Fig. 1) 2 . Chitosan has a sim i lar struc ture to that of cel lu lose, but shows many prop er ties that dif fer from the lat ter, for ex ample, chitosan is con sid ered more chem i cally ver sa tile than cel lu lose, due to the pres ence of an amino group. This group gives chitosan sol u bil ity in or ganic ac ids (ace tic acid, for mic acid) and di luted in or ganic ac ids (chloridric acid). This poly mer has been the ob ject of con tin ued study for sev eral de cades. In par tic u lar, its metal-binding property has led to the use of chitosan as a low-cost ma te rial in, waste wa ter treat ment plants and streams con tam i nated by the ac cu mu la tion of toxic met als re leased by in dus trial activ i ties [3][4][5] .In a re cent re port chitosan was used in the im mo bi li zation and char ac ter iza tion of ni trite, per manga nate, io dide Ar ti cle

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