ATT AVLÄGSNA ROST FRÅN PAPPER - Ett jämförande av två kelatbildare i kombination med natriumdisulfit

Abstract

Sodium metabisulfite has been reported as a less dangerous for the practitioner alternative than other reducing agents used for removing iron corrosion from paper. Since it has mainly been studied with EDTA as a chelating agent this paper sets out to compare the effect of EDTA and triammonium citrate in combination with sodium metabisulfite on iron corrosion on paper via visual assessment and spectrophotometry, in 5% (w/v) and 2.5% solutions. The risks the two substances pose for the practitioner and the paper being treated is discussed. Triammonium citrate is found to be less effective as a chelating agent but produces results with less variation. A difference cannot be seen with only visual assessment between papers treated with the two chelating agents. Solutions with sodium metabisulfite and triammonium citrate are too acidic to use on paper without first raising the pH. As it is corrosive and poisonous EDTA poses a larger danger than triammonium citrate, which is an irritant. Both chelating agents risk lowering the calcium levels in paper.