Evaluation of Elimination of Sodium Borohydride from Paper by Acid Washing

• Main Authors: LEE, CHIA-CHI, 李家綺
• Other Authors: TSAI, FEI-WEN
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/90746565263609025822

碩士 === 國立臺南藝術大學 === 博物館學與古物維護研究所 === 104 === In paper conservation treatments, after bleaching with sodium borohydride, washing by water alone is the most common way to eliminate residual agents from paper. But does it remove well? Or should we get other chemicals involved in this process? It remains to be verified. Bleaches removal by dilute acid solution is based on the characteristic of sodium borohydride which decomposes rapidly when pH is lowered. In this study, acid washing was compared with washing in pure water or an aqueous solution contained calcium compound. And through analyzing empirical results, the feasibility and effectiveness of acid washing would be confirmed. Whatman qualitative filter paper was chosen for the experiment and prepared under different conditions. The bleached samples were analyzed directly after the bleaching treatment by atomic absorption spectroscopy to determine the sodium ion content, which might indicate roughly the amount of sodium borohydride or borax. Besides, cold extraction method, CIE color systems, and Cannon-Fenske capillary viscometer method also be used to detect the optical and chemical properties of samples before-and-after moist heat aging treatment. The result shows that acid washing could reduce the sodium ion content efficiently, and even less than original or water-washed one. The pH of acid-washed sample keeps neutral during aging process. However, its color stability and cellulose degree of polymerization are slightly worse, especially the latter, than the sample washed by water or calcium-containing solutions. To sum up, water washing remains more stability for cellulose than acid washing, and the effect of washing by calcium-containing solution is between those two methods.