Exposure of Deacidified and Untreated Paper to Ambient Levels of Sulfur Dioxide and Nitrogen Dioxide: Nature and Yields of Reaction Products

This project was aimed at investigating the nature and yields of the reaction products resulting from exposure of deacidified and untreated paper to ambient levels of sulfur dioxide and nitrogen dioxide, separately and as a mixture. Two types of paper, newsprint and white wove, were used. Both SO2 and NO2 were absorbed throughout the 13- to 29-week exposures and were removed at the same rate whether present alone or as a mixture. The paper had a larger capacity for uptake of SO2 than for uptake of NO2. Sulfate was the only sulfur-containing product observed irrespective of paper type, deacidified or not, and accounted for 65 ± 30% of the absorbed SO2. Newsprint contained more sulfate than did white wove, and untreated paper had the lowest sulfate yields. Sulfite, bisulfite, and other oxidizable sulfur-containing products were absent. Nitrite and nitrate, the two nitrogen-containing products observed, together accounted for all of the absorbed NO2. Deacidified paper yielded both nitrite and nitrate; untreated paper yielded only nitrate. The ratio of nitrate + nitrite to sulfate was lower in deacidified paper (0.2–0.5%) than in untreated paper (0.6–2.0%). Nitrite accounted for 41% of the total (nitrate + nitrite) upon exposure to NO2 alone but for only 9% upon exposure to NO2 in the presence of SO2.