Electrochemical removal of stains from paper cultural relics based on the electrode system of conductive composite hydrogel and PbO2

Characterisation and restoration of a severely damaged paper archive from the Qing Dynasty

In this study, a severely damaged official document produced in the Qing Dynasty (1911 A.D.), was characterized using a range of techniques and subsequently restored using the traditional Chinese conservation methods. The pH and crystalline index of the paper were measured using a pH meter, attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and X-ray Diffraction (XRD) spectroscopy. The results indicate that the paper archive is acidic and degraded, which is also supported by the broken fibres as observed using scanning electron microscopy (SEM). Then, the properties and durability of the conservation materials, including the conservation paper made of Wikstroemia fibre and wheat starch paste, were explored by determination of colour difference, whiteness, pH, tensile strength, and observation of cross-sectional features before and after dry- and moist-heat degradation. The results demonstrate the conservation materials presented good durability and were then used to perform subsequent conservation treatments, including the assembly of paper pieces and the application of backing paper, to provide additional mechanical support for the preservation of the historical paper archive.

Multi-Functional Repair and Long-Term Preservation of Paper Relics by Nano-MgO with Aminosilaned Bacterial Cellulose

Paper relics, as carrieres of historical civilization's records and inheritance, could be severely acidic and brittle over time. In this study, the multi-functional dispersion of nanometer magnesium oxide (MgO) carried by 3-aminopropyl triethoxysilane-modified bacterial cellulose (KH550-BC) was applied in the impregnation process to repair aged paper, aiming at solving the key problems of anti-acid and strength recovery in the protection of ancient books. The KH550-BC/MgO treatment demonstrated enhanced functional efficacy in repairing aged paper, attributed to the homogeneous and stable distribution of MgO within the nanofibers of BC networks, with minimal impact on the paper's wettability and color. Furthermore, the treatment facilitated the formation of adequate alkali reserves and hydrogen bonding, resulting in superior anti-aging properties in the treated paper during prolonged preservation. Even after 30 days of hygrothermal aging tests, the paper repaired by KH550-BC/MgO was still in a gently alkaline environment (pH was about 7.56), alongside a 32.18% elevation compared to the untreated paper regarding the tear index. The results of this work indicate that KH550-BC/MgO is an effective reinforcement material for improving the long-term restoration of ancient books.

Mineral Clays for Cleaning Tidelines on Paper-Based Artworks

Clay minerals possess several properties such as ion exchange capability, alkaline pH, adsorptive, swelling, and plastic behaviour, most of which are governed by their interactions with water. They have the capacity to interact with soluble molecules, which is particularly interesting for art conservation treatments. For all these reasons clays deserve to be considered for green and sustainable paper conservation interventions. In this work two phyllosilicates with different properties, namely montmorillonite and sepiolite, were investigated for the removal of tidelines on artificially aged paper samples. Water exchange, cleaning efficiency, and pH were evaluated comparing the clays to gellan gum, a benchmark cleaning hydrogel. A pouch made with regenerated cellulose was used to avoid direct contact of the minerals with the paper. The water sorption capacity of the clays combined with the specific permeability of the cellulosic membrane allowed for a homogeneous and easy to control cleaning. The formation of new tidelines, an inherent risk to any local conservation treatment of paper, was avoided. As an example, sepiolite was used for the local cleaning of a paper-based artwork’s multiple tidelines.

Effects of Cu2+/Zn2+ on the electrochemical performance of polyacrylamide hydrogels as advanced flexible electrode materials

Previously, solid-state electrode materials have been utilized for the fabrication of energy storage devices; however, their application is impeded by their brittle nature and ion mobility problems. To address issues faced in such a modern era where energy saving and utility is of prior importance, a novel approach has been applied for the preparation of electrode materials based on polyacrylamide hydrogels embedded with reduced graphene oxide and transition metals, namely, Cu²⁺ and Zn²⁺. The fabricated hydrogel exhibits high electrical properties and flexibility that make it a favorable candidate to be used in energy storage devices, where both elastic and electrical properties are desired. For the first time, a multi-cross-linked polyacrylamide hydrogel was constructed and compared in the presence of other electro-active materials such as reduced graphene oxide and transition metals. Polyacrylamide hydrogels embedded with reduced graphene oxide demonstrate excellent electrical properties such as specific capacitance, least impedance, low phase angle shift and AC conductivity of 22.92 F g^-1, 2115 Ω, 2.88° and 0.67 μδ m^-1 respectively as compared to Cu²⁺- and Zn²⁺-loaded hydrogels, which block all available active sites causing an increase in impedance with a parallel decrease in capacitance. The capacitance retention and coulombic efficiency calculated were 88.22% and 77.23% respectively, indicating high stability up to 150 cycles at 0.1 A g^-1. Storage moduli obtained were 10.52 kPa, which infers the more elastic nature of the hydrogel loaded with graphene oxide than that of other synthesized hydrogels.

Gellan Gum Hydrogel as an Aqueous Treatment Method for Xuan Paper

Aqueous cleaning of works of art on paper is one of the most important and delicate steps in a conservation process. It allows the removal of inorganic (metals) and organic substances, such as degradation products and other contaminants. These substances are responsible for yellowing, weakening, and loss of mechanical properties of paper. In this article, the cleaning effect of gellan gum was assessed on xuan paper, a traditional Chinese paper different in composition and papermaking technology compared to many Western papers. To assess the effect of gellan gum on xuan paper, its characteristics were studied before and after cleaning utilizing non-invasive and micro-invasive techniques. Results were compared to those obtained when treating Western papers and indicated that gellan gum can be applied effectively for aqueous cleaning of xuan paper.