ISSN print edition: 0366-6352
ISSN electronic edition: 1336-9075
Registr. No.: MK SR 9/7
Interactions in iron gall inks
V. Jančovičová, M. Čeppan, B. Havlínová, M. Reháková, and Z. Jakubíková
Department of Graphic Arts Technology and Applied Photochemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-812 37 Bratislava, Slovak Republic
Received: 30 January 2007 Revised: 12 April 2007 Accepted: 16 April 2007
Abstract: Simple iron gall inks composed of gallic acid, ferrous sulfate, and gum arabic and in some cases also of copper(II) sulfate were prepared. The process of iron ion complex formation with gallic acid was investigated using UV-VIS spectroscopy, pH measurements, and by monitoring the concentration changes of Fe(II) ions. The admixture of Fe(II) ions to gallic acid induced a bathochromic shift of absorption bands at 215 nm and 265 nm in the UV-VIS spectra. Formation of a new absorbance band in the visible area was also observed and used to calculate the initial rate of complex formation. Concurrently, the pH values and the concentration of Fe(II) ions in the solution decreased. Gum arabic significantly enhanced the complex formation and its stability. On the contrary, the addition of Cu(II) ions to the solution decelerated the complex formation considerably.
Keywords: gall ink - ferrous sulfate - copper(II) sulfate - complex formation - spectral properties
Full paper is available at www.springerlink.com.
Chemical Papers 61 (5) 391–397 (2007)