Research On The New Generation Mechanism Of Active Oxygen In Blue-black Ink And Its Correlation With Archival Corrosion

Paper fiber degradation is a severe challenge to paper archives preservation.Due to the complex composition of paper,storage environment is difficult to control,leading to a number of fiber degradation factors,factors affecting its durability can be divided into internal factors and external factors.The degradation factors of paper fiber are numerous for the complex composition,and unmanageable storage environment.Its durability can be divided into internal factors and external factors.Internal factors include the materials used in papermaking process and the manufacturing technique,external factors refer to the interference from external environment such as temperature,humidity,acid,alkali,light,mold and insect moth,etc.,which also include the materials used for the handwriting of paper archives.In the process of discussing the writing materials used,it is found that the iron gall ink has the most serious damage to the paper fiber.Traditionally,the degradation of paper fiber caused by ink mainly includes acid hydrolysis degradation and iron or copper ion oxidation catalyzed cellulose macromolecules.According to the literature,gallic acid can produce hydrogen peroxide in the air.In terms of the fact that iron gall ink is composed of iron ions and gallic acid,in this paper,it is proposed that gallic acid in ink can oxidize spontaneously with air to generate hydrogen peroxide under certain conditions,which can interact with the bivalent iron to form Fenton reaction to produce hydroxyl radicals.And hydroxyl radical with strong oxidation is thought to be the fundamental cause of paper corroded by iron gall ink.This speculation provides a new insight into the mechanism of the degradation of paper fiber caused by iron gall ink.In addition,the study found that the handwriting written with iron gall ink still has a high content of ferric iron ions exposed to air for a long time.Nonetheless,the literature did not give the reason why ferric iron,the readily oxidized,can still exist in the ink.This thesis mainly focuses on the above two aspects and the research content and corresponding conclusions are as follows:1.In order to prove that the reaction of gallic acid with air can produce hydrogen peroxide,a solution with certain concentration of gallic acid was prepared and stirred in different atmosphere.The related systems were tested by oxygen absorption in gallic acid solution,chemiluminescence based on luminol to detect hydrogen peroxide,and fluorescence probe based on hydroxyl radical to oxidize phthalic acid.The results showed that(1)under sufficient oxygen atmosphere,the gallic acid solution can sustainable absorb oxygen;(2)Luminol and gallic acid solution have obvious chemiluminescence phenomenon within a certain range of concentration;(3)Hydroxyl radicals can be generated in gallic acid-Fe2+ system.The following conclusions can be drawn from the above experimental results that alkaline gallic acid solution can be oxidized by oxygen to prodece hydrogen peroxide.This consequence provides an important reference for subsequent experiments to reveal the mechanism of iron gall ink eroding paper.2.With cellulose nanofiber,gallic acid and ferrous sulfate as the main material,different cellulose dispersion were prepared with iron gall ink and tis simulated solution including gallic acid,ferrous sulfate and gallic acid+ferrous sulfate solutions.To reveal the relationship between gallic acid and iron ions on the properties of cellulose nanofibers.The morphology and structure of the cellolose nanofiber above mentioned were characterized by technologies of SEM,FT-IR and XRD.The results showed that(1)nanocellulose aqueous solution is easy to form and transact into linked aggregates at a high concentration.And the filamentous fiber can be obtained with aggregation degree reducing by decreasing the concetration.This change was related to the strong hydrogen bonding between nanocellulose.(2)Cellulose nanofiber is prone to agglomeration in acidic medium,while the aggregation of inter-cellulose will be decreased with the acidity reducing washed by water.This was related to the fact that the hydrogen bond between cellulose was easily strengthened under acidic conditions.(3)Iron gall ink has a serious corrosion effect on cellulose nanofiber and presents a phenomenon of fragmentation.The stronger corrosion effect of iron gall ink on cellulose is closely related to the coexistence of iron ions and gallic acid.The effect is related to the weakening of hydrogen bond and the decrease of crystallinity.3.Using filter paper and two main components(gallic acid,ferrous sulfate)of iron gall ink as the material to prepare GA,FS and FG solutions to impregnate paper,and then subjected to artificial aging treatment at different times.Several technologies including SEM,XRD,FT-IR,TG,UTM,pH meter and EPR were applied to characterize the composition,structure and mechanicle properties of paper above mentioned.The results showed that(1)the degradation of the latter two kinds of paper fibers were more serious though the pH of GA,FS and FG paper were similar.Moreover,FG solution still had strong corrosion on paper under the situation of FG paper acidity was higher than FS.This conclusion indicated that gallic acid and iron ions had synergistic effects on the degradation of paper fibers.(2)There is still ferric iron in handwriting written with iron gall ink exposure in the air,which is related to the reducing component gallic acid in the ink.(3)There are a variety of free radicals with oxidation effect in aging paper.Highly oxidizing hydroxyl radicals will be produced when gallic acid and ferric iron coexist,which is related to the Fenton reaction between the hydrogen peroxide generated by gallic acid in the air and the ferric iron in ink.For the file witten with iron gall ink exposure in the air,the spontaneous generation of hydroxyl radicals in ink writing is the main cause of the strong corrosion on paper caused by iron gall ink.In this thesis,the theory that gallic acid can produce hydrogen peroxide through autooxidation was proved,and the mechanism of paper fiber degradation when gallic acid and ferrous sulfate exist simultaneously was proposed and verified.It is revealed that iron gall ink handwriting has a possible mechanism of maintaining ferric iron in the air.This conclusion deepens the understanding of the mechanism of iron gall ink corroding paper,provides new insights for the research on the protection of iron gall ink paper archives,and has positive theoretical significance and application value for the preservation and restoration of archives.