Quaternary Alloy Quantum Dots as Fluorescence Probes for Total Acidity Detection of Paper-Based Relics

Abstract

Traditionally, the acidity of paper-based relics was determined by an extraction method and using a pH meter. This method could not obtain the total acidity of the paper-based relics because it only detected the concentration of free protons in the aqueous soaking solution. To overcome this defect, a new method for determining the total acidity of paper-based relics has been established by using quaternary alloy quantum dots. The quantum dots, CdZnSeS, modified by p-Aminothiophenol (pATP) were prepared, and their composition and structure were characterized. The fluorescence behavior of prepared quantum dots with acidity was investigated. The following results were obtained. The fluorescence of CdZnSeS-pATP quantum dots could decrease with increases in acidity because pATP dissociated from the surfaces of the quantum dots due to protons or undissociated weak acids. Based on this feature, a method for determining the acidity of paper-based relics was constructed, and this method was used to evaluate the acidity of actual paper-based relics. Obviously, for a given paper sample, since both free protons and bound protons can be determined by this method, the acidity measured by this method is more reasonable than that by pH meter.

A Review of Applications of Nanocellulose to Preserve and Protect Cultural Heritage Wood, Paintings, and Historical Papers

“…The degradation of historical papers in museums, libraries, and archives is due to different factors such as humidity, light, air, pollution, and bacteria attacks; moreover, this type of artworks is often subject to mechanical damage in terms of cracks, cuts, and deformations, especially in the borders, and is more exposed to atmospheric agents that induce the lowering of mechanical properties of paper. However, regarding the other cellulose-based artworks discussed before, in this case, the main degradation process is also acidic hydrolysis, which produces a considerable decrease in the mechanical strength of cellulose fibers [16,[89][90][91]. To provide a structural reinforcement of paper, many strategies have recently been developed using both synthetic and natural materials [92].…”