The Screening Of Deacidification Agents And Their Deacidification Effect With Help Of Ultrasound For Old Newspaper

Ancient books are a precious cultural heritage, and also the treasure of the world. As time went by, these ancient books, especially for the old newspapers have appeared all kinds of "face changing" phenomenon.The acidification of paper is one of the main reasons which cause this phenomenon.Firstly, choosing a suitable paper deacidification agent is very important for the deacidification of ancient books. Four kinds(calcium salt, magnesium salts, sodium borohydride salts and boric acid salts) of high quality, inexpensive, environmentally friendly deacidification reagents(calcium hydroxide, calcium propionate, magnesium acetate, magnesium ethoxide, sodium borohydride magnesium, potassium borohydride, lithium borate, sodium borate and potassium tetraborate) were chose to compare with each other in their own category. According to the whiteness, pH and mechanical performance parameters of deacidification and deacidification aging before and after, four deacidification reagents were obtained, which could keep the pH of the paper in a good range of7.0-8.5and improve the mechanical properties of paper. Among the four agents, the growth of tensile strength and tear strength of paper deacidified by lithium borate was the highest, the stretch of calcium propionate after deacidification was the best and the folding endurance of magnesium ethoxide was better than other three. In the color aspect, magnesium ethoxide was better than other agents. Considering the above, the optimum deacidification agent was lithium borate. At the same time, the above conclusions could also provide strong reference in the later mass deacidification.In order to improve the efficiency of paper deacidification, the ultrasound was used to assist lithium borate, potassium tetraborate and potassium borohydride for the paper deacidification.The amount of paper was soaked in the solution of lithium borate, potassium tetraborate and potassium borohydride in their own optimum concentration under the condition of23℃and RH50%. Optimization condition was ultrasonic power100W, frequency40kHz and time12min. On the basis of the changes of pH, whiteness and mechanical performance parameters of the paper properties and the analysis of SEM, FTIR before or after using ultrasound, the results were as follows: Ultrasound could obviously reduce the deacidification time of paper, improve the mechanical properties of paper and have no negative effect on the paper fibers.The drying speed of paper after deacidification is also a major factor affecting the paper deacidification efficiency. In the experiment ethanol was adopted to accelerate paper drying. The paper was treated with two kinds of drying methods (one using ethanol in the drying process and the other not using). On the basis of the changes of pH, whiteness and mechanical performance parameters of the paper properties before or after drying, the results were as follows:Ethanol could accelerate paper drying, and the drying method had no effect on the paper.