Cyclopentasiloxane (D5) as a Non-Polar Masking Agent for Water-Sensitive Substrates During Polar Solvent Treatment

D5 (decamethylcyclopentasiloxane), a non-polar solvent that evaporates slowly, was tested for its suitability as a temporary masking agent for water-sensitive media on paper objects undergoing aqueous treatment. Three different treatment-related settings were tested on five different paper types, some prepared with water-soluble inks. In 10-min water immersion treatments, D5 proved largely ineffectual in protecting the water-soluble inks. In conjunction with melt-applications of cyclododecane, the addition of D5 enhanced its barrier function only in one case. To test the ability of D5 to prevent tideline formation, the test samples received applications of water, acetone, and a water-ethanol-mixture, creating an interface with freshly D5-impregnated areas. The papers were evaluated visually (VIS, UVA), some after artificial aging. D5 diminished the formation of visible tidelines in the two internally sized papers with low water absorbency in contact with acetone and the ethanol-water mixture, but did not prevent tidelines in contact with water. It also did not protect water-absorbent paper. The results indicate that D5, which is miscible with ethanol and acetone, may disperse tidelines caused by these solvents, but it proved largely insufficient for protecting media during water immersion.

Potential for the valorisation of brewer’s spent grains: A case study for the sequential extraction of saccharides and lignin

This study highlights the possibility of using brewers’ grains (BSGs) for the successive extraction of the main lignocellulosic biopolymers, namely, cellulose, hemicelluloses and lignin. An exhaustive chemical characterisation revealed a variability of composition in distinct batches of BSGs, depending on their origin and the brewing process used. In particular, the protein content can vary from 13wt% to 23wt%, which is accompanied by a change in the hemicelluloses content from 9% to 23% (in the samples of our study). By applying a two-step aqueous treatment, involving an acid (1.25% v/v aq. H2SO4) and a base (3% w/v aq. NaOH) at a temperature of 120°C and fixed reaction time of a few tens of minutes (15–90 minutes), more than 80% of hemicelluloses could be recovered. Cellulose could be isolated at more than 68%, while a high purity lignin could be recovered from a lignin-rich fraction (70wt%). Our work also suggests that the variability of the chemical composition of these BSGs is a hindrance to achieving process standardisation and large-scale exploitation. The pooling of various materials is therefore not a recommended option, and the preliminary chemical analysis of the composition is therefore a prerequisite for an efficient extraction process.

Surface Modification To Alleviate PVDF Membrane Fouling During Milk Protein Microfiltration

The interest in using polyvinylidene fluoride (PVDF) membrane in order to separate casein and serum proteins has been raised due to its significant stability. However, the high hydrophobicity of PVDF membrane causes severe fouling during filtration processes. Ozonation, a surface modification process in which polar groups would be formed on the membrane surface, is widely known for its high efficiency. In the present study, the main objective was to optimize the ozonation parameters to reach the minimum fouling while the maximum mechanical strength could be retained. The contact angle of a water droplet on the membrane surface decreased from 73.5° to 50.4° after the treatment of the membrane at the optimal gaseous phase ozonation. This indicates an increase in the hydrophilicity of the treated membrane. Also, filtration performance demonstrated a lower fouling occurrence on the treated membrane as compared to the untreated one. Although gaseous ozonation yielded a slightly better performance in comparison to the aqueous treatment, the membrane treated with aqueous phase ozonation was benefited from conserving its mechanical strength. Activated carbon helped decreasing the contact angle and fouling as compared to the non-catalytic aqueous treatment while the tensile strength was not affected

Surface Modification To Alleviate PVDF Membrane Fouling During Milk Protein Microfiltration

The interest in using polyvinylidene fluoride (PVDF) membrane in order to separate casein and serum proteins has been raised due to its significant stability. However, the high hydrophobicity of PVDF membrane causes severe fouling during filtration processes. Ozonation, a surface modification process in which polar groups would be formed on the membrane surface, is widely known for its high efficiency. In the present study, the main objective was to optimize the ozonation parameters to reach the minimum fouling while the maximum mechanical strength could be retained. The contact angle of a water droplet on the membrane surface decreased from 73.5° to 50.4° after the treatment of the membrane at the optimal gaseous phase ozonation. This indicates an increase in the hydrophilicity of the treated membrane. Also, filtration performance demonstrated a lower fouling occurrence on the treated membrane as compared to the untreated one. Although gaseous ozonation yielded a slightly better performance in comparison to the aqueous treatment, the membrane treated with aqueous phase ozonation was benefited from conserving its mechanical strength. Activated carbon helped decreasing the contact angle and fouling as compared to the non-catalytic aqueous treatment while the tensile strength was not affected

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.

Resizing: A Brief Review of Restoration and Conservation Literature from the 17th to the 21st Century

From the first half of the seventeenth century until the beginning of the twentieth century resizing was common practice after each aqueous treatment to replace the loss of original sizing, but it is used much less frequently today. As already described in early sources, resizing in modern conservation practice still serves three main purposes: increasing mechanical stability, modifying the surface texture of abraded papers by decreasing their surface roughness and consolidating loosened fibres and preparing the paper substrate for inpainting. Today’s practice, however, differentiates more carefully between an improvement in mechanical stability and increased resistance to physical and chemical degradation processes. While previously almost exclusively protein glues were used for resizing, today gelatine and cellulose ethers are among the most commonly used sizing agents. The solution concentrations used for resizing have significantly decreased: gelatine is used in 0.5 % (w/v) to 1 % (w/v) solutions today, while historic literature recommends 1.6 % (w/v) to 3.5 % (w/v) protein glues. Concerning application techniques, mainly immersion, closely related to tub sizing used during paper manufacture and local or overall brush applications were used for historic sizing. Spraying, which was introduced at the beginning of the second half of the twentieth century, is recommended for resizing drawings to prevent friable media from being smudged.