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To expand the application field of the pulping industry, this study conducted a series of sample preparations for processing cellulose nanocrystals (CNCs) from a dry hardwood pulp to achieve optimal sulfuric acid hydrolysis. The properties of laboratory-prepared pulp CNCs (P-CNCs) were investigated with different preparation conditions including sulfuric acid concentrations, hydrolysis temperatures, and hydrolysis durations. Results showed a gradient of color changes observed with the increase of hydrolysis duration and temperature. Under certain conditions, the derived P-CNCs exhibited nanoscale dimensions, detected by transmission electron microscopy, and a crystallinity index similar to commercial products. In addition, the surface sulfate groups were assumed to be contributed by sulfuric acid hydrolysis. However, a high acid concentration and long hydrolysis processing duration introduced more sulfate groups on the derived P-CNCs, which may have acted as flame retardants and, thus, increased the amount of char residue.

A Japanese painting paper is sized with an aqueous solution of alum and animal glue followed by brushing with a mixture of pigments of various colours and aqueous animal glue solution. Subsequently, to mount the Japanese painting to a hanging scroll, the backside of the painting is lined with a first lining paper using wheat starch paste for mechanical support. To evaluate the permanence of the painting paper as a composite material in the hanging scroll, the deterioration behaviour of the unlined painting paper and the lined painting paper was compared considering the material dynamics. After moist heat accelerated ageing (80°C, 65% RH), in the sample immersed in a CuSO4・5H2O solution, cellulose was oxidised by Cu2+ to generate organic acids in the painting paper, and Cu2+ and organic acids migrated to the lining paper. Consequently, the discolouration and oxidation of the painting paper in the lined complex were relatively low compared with those of the unlined painting paper. The pH decrease in the painting paper was also small in the lined complex. Moreover, if the animal glue solution was coated on the painting paper, a buffer effect was shown to operate against the organic acids derived from the oxidation of Cu2+, thereby inhibiting the migration of Cu2+ into the lining paper. In conclusion, the presence of the lining paper inhibited the decrease in the physical strength and degree of polymerisation of the cellulose in the painting paper, thus contributing to its permanence in the lined hanging scroll. [ABSTRACT FROM AUTHOR]

A simple one-step microwave-assisted synthesis approach for preparing fluorescent carbon dots (CDs) with an average diameter of 7.86 nm from 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated-oxidized cellulose nanofiber (TEMPO-CNF) and 4,7,10-Trioxa-1,13-tridecanediamine is reported in this study. The synthesized TEMPO-CDs exhibited excitation-dependent emission, with optimal excitation and emission wavelengths of 390 nm and 449 nm (bright blue ray), respectively. The fluorescence properties of the synthesized TEMPO-CDs were successfully and selectively quenched by Fe3+ within seconds and by Mn2+ after 10 min. Thus, this phenomenon is further applicable to the development of a fluorescence-sensing system for the quantitative detection of Fe3+ and Mn2+ using the same CD probe; this is the first time such findings have been reported in the CD-related literature. [ABSTRACT FROM AUTHOR]

With the aim of developing a new easy-to-use method for rescuing flood-damaged paper, the effect of saltwater on the inhibition of fungal growth on paper was investigated. This procedure could be used instead of, or assisted by freeze drying. Cellulose-digesting Trichoderma reesei, three types of fungi representative of fungi growing on paper (T. reesei, Aspergillus terreus, and Aureobasidium pullulans) and various naturally airborne fungi were cultured on cellulosic materials in liquid media containing artificial seawater with different salt concentrations. The addition of salts successfully inhibited the growth of T reesei on microcrystalline cellulose at the concentration of 3.2% (m/m) or higher. The critical salt concentration, 3.2%, is within the general range of salt content in seawater. Other solutions of salts similar to sodium chloride also inhibited fungal growth. Although the observed growth-inhibiting effect was attributed to the high osmotic pressure of the salt solution, physiological effects depending on ion species used were also considered to be possible. The growth of all three types of fungi on copy paper was inhibited effectively when the salt concentration was increased. The growth of various fungi on pure cellulose, with enough oxygen supplied to pores, was completely inhibited (as assessed by visual examination) for 24 days at salt concentrations of 3.5% (m/m) or greater. The fact that the effect of saltwater on cellulosic materials was observed even under optimum medium conditions implies that fungi would be considerably inhibited on flood-damaged paper immersed in saltwater. This method is a promising first aid measure when circumstances do not allow for flood-damaged paper to be dried immediately. [ABSTRACT FROM AUTHOR]

The saltwater immersion method was developed to inhibit mould growth on flood- or tsunami-damaged paper. Commercially available fine paper used for printing and writing showed decreased tensile indices after saltwater immersion. The salt remaining in the paper tended to increase the moisture content because of the salt deliquescence and moisture in the air. The tensile index was restored by removing salt from the paper. Crystallization and distribution of salt in interfibre pores were also considered to influence interfibre rebonding. The difference in the fibre responses to saltwater depended on the relationship between nano-scaled pores in the fibre walls, osmotic pressure, and the degree of sizing, which resulted in low water retention values. More of the starch applied as a surface sizing agent was dissolved or dispersed during distilled water immersion than saltwater immersion. This loosened the fibre network, which was a factor that decreased the sizing degree of the paper. [ABSTRACT FROM AUTHOR]

• The membrane was made of biodegradable cellulose alone. • A facile method fabricated the membrane with unique surface chemistry. • The underwater oleophobicity of two types of cellulose nanofiber was reported for the first time. • A high flux rate and separation efficiency was achieved by gravitational force alone. A cellulose sponge was fabricated through xanthation to dissolve cellulose, and heating to regenerate the cellulose solution. The obtained cellulose sponge showed good physical strength with resilient ratio and unrecoverable proportion at 60% compression stress of 42.6% and 25.7%, respectively. Bamboo-based counter collision cellulose nanofiber (MECH-CNF) prepared by the aqueous counter collision method and wood-free fiber-based 2,2,6,6-tetramethylpiperidine-1-oxyl oxidized cellulose nanofiber (TEMPO-CNF) were used to increase the hydrophilicity and underwater oleophobicity of the cellulose sponge. Oil contact angles in air and underwater were investigated to evaluate oleophobicity. The TEMPO-CNF-deposited cellulose sponge (TCNF-membrane) demonstrated higher oleophobicity underwater than MECH-CNF-deposited cellulose sponge (MCNF-membrane). Oil-water separation was tested to evaluate the possibility of water treatment applications. The flowrate of the MCNF-membrane was 3.73 × 103 L m−2 h−1 and much higher than that of the TCNF-membrane at 166 L m−2 h−1, both at separation efficiency levels higher than 99% by gravitational force alone. [ABSTRACT FROM AUTHOR]