Superstrong, Lightweight, and Exceptional Environmentally Stable SiO2@GO/Bamboo Composites

Processing natural bamboo into white bamboo through photocatalyzed lignin oxidation

Scalable and highly efficient bamboo whitening remains a great challenge. Herein, an effective bamboo whitening strategy is proposed based on photocatalyzed oxidation, which involves H2O2 infiltration and UV illumination. The as-prepared white bamboo well maintains the nature structure of natural bamboo and demonstrates high whiteness and superior mechanical properties. The absorbance value is significantly decreased to 3.5 and the transmittance is increased to 0.04 % in UV-visible wavelength range due to the removal of light-absorbing chromospheres of lignin, resulting in a high whiteness when the UV illumination time is 8 h. In addition, the white bamboo displays a high tensile strength of 30 MPa and a high flexural strength of 36 MPa due to the well-preserved lignin units (lignin preservation is about 89 %). XRD patterns and analysis show that photocatalyzed oxidation has no effect on the crystal parameters of cellulose. Compared with the traditional bamboo whitening technology, our photocatalyzed oxidation strategy demonstrates significant advantage including chemical and time conservation, high efficiency, environment friendliness, and mechanical robustness. This highly efficient and environmentally friendly photocatalyzed oxidation strategy for the fabrication of white bamboo may pave the way of bamboo-based energy-efficient structural materials for engineering application.

Multifunctional actuators integrated with the function of self-powered temperature sensing made with Ti3C2Tx-bamboo nanofiber composites

In recent years, multifunctional actuators have received increasing attention and development. In particular, researchers have conducted extensive research on intelligent actuators with integrated sensing functions. Temperature is an important parameter for the deformation of bilayer thermal actuators. By obtaining the temperature information of a bilayer thermal actuator, the deformation amplitude and its state can be judged. Thus, there is an urgent need to develop a type of intelligent actuator with a self-powered temperature sensing function. Herein, Ti3C2Tx-based composites modified with bamboo nanofibers have been proposed and applied to intelligent actuators integrated with a self-powered temperature sensing function. By utilizing the coefficients of thermal expansion between Ti3C2Tx-bamboo nanofiber composites and a polyimide film, a bilayer photo/electro-driven thermal actuator is designed which shows a bending curvature as large as 1.9 cm-1. In addition, Ti3C2Tx-bamboo nanofiber composites have a Seebeck coefficient of -9.15 μV K-1, and are N-type thermoelectric materials and can be used as the component of self-powered temperature sensors. Finally, a series of practical applications were designed, including a light-driven floating actuator (with a moving speed of 5 mm s-1), biomimetic sunflowers, bionic tentacles, and a multifunctional gripper integrated with a self-powered temperature sensing function. In particular, the multifunctional grippers can output voltage signals carrying their temperature information without external complex power sources, demonstrating their potential for remote monitoring. The above results demonstrate that Ti3C2Tx-bamboo nanofiber composites have extensive practical applications in fields such as self-powered sensors, flexible thermoelectric generators, and soft actuators.

Surface Phenomena with the Participation of Sulfite Lignin under Pressure Leaching of Sulfide Materials

Searching for surfactants which can eliminate the occluding effect of molten elemental sulfur formed in the process of leaching sulfide ores under pressure (autoclave leaching) is relevant. However, the choice and use of surfactants are complicated by the harsh conditions of the autoclave process, as well as the insufficient knowledge of surface phenomena in their presence. This paper presents a comprehensive study of interfacial phenomena (adsorption, wetting, and dispersion) involving surfactants (using lignosulfonates as an example) and zinc sulfide/concentrate/elemental sulfur under conditions simulating sulfuric acid leaching of ores under pressure. The influence of concentration (C_LS 0.1-1.28 g/dm³), features of the molecular weight (M̅_w, 9.250-46.300 Da) composition of lignosulfates, temperature (10-80 °C), addition of sulfuric acid (CH₂SO₄ 0.2-10.0 g/dm³), and properties of solid-phase objects (surface charge, specific surface area, presence and diameter of pores) on surface phenomena at the liquid-gas and liquid-solid interfaces was revealed. It was found that with an increase in molecular weight and a decrease in the degree of sulfonation, the surface activity of lignosulfonates at the liquid-gas interface, as well as their wetting and dispersing activity with respect to zinc sulfide/concentrate increases. It has been found that an increase in temperature contributes to the compaction of the macromolecule of lignosulfonates, as a result of which their adsorption at the liquid-gas and liquid-solid interface in neutral media rises. It has been shown that the introduction of sulfuric acid into aqueous solutions increases the wetting, adsorption, and dispersing activity of lignosulfonates with respect to zinc sulfide. The latter is accompanied by a decrease in the contact angle θ (by 10 and 40°) and an increase in both the specific number of zinc sulfide particles (not less than 1.3-1.8 times) and the content of fractions with a size of -3.5 μm. It has been established that the functional effect of lignosulfonates under conditions simulating sulfuric acid autoclave leaching of ores is implemented through the adsorption-wedging mechanism.

Surface Functionalization of Bamboo with Silver-Reduced Graphene Oxide Nanosheets to Improve Hydrophobicity and Mold Resistance

A natural polyphenolic compound was used to assemble nanocomposites. Owing to its stable bioactive properties, bamboo has earned significant attention in material science. Its high nutrient content and hydrophilicity makes bamboo more vulnerable to mold attacks and shortened shelf lives. To produce efficient, multipurpose, long-life bamboo products, a novel technique involving an immersion dry hydrothermal process was applied to impregnate the bamboo with polyphenol-assisted silver-reduced graphene oxide nanosheets. Curcumin (Cur), a natural polyphenol found in the rhizome of Curcuma longa, was used in the preparation of curcumin-enhanced silver-reduced graphene oxide nanosheets (Cur-AgrGONSs). The nanocomposites and nanocomposite-impregnated bamboo materials were examined by field emission scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. At the same time, a phytopathogen was isolated from infected bamboo products and identified by internal transcribed spacer (ITS) sequences. The nanocomposites effectively inhibited the growth of the isolated fungus. The mold resistance and moisture content of both the treated and untreated bamboo timbers were also examined to determine the efficiency of the prepared nanocomposite. The antifungal activity and hydrophobicity of the bamboo materials were significantly enhanced after the incorporation of curcumin-enriched silver-loaded reduced graphene oxide nanosheets (B@Cur-AgrGONSs). This research outcome confirms that the nanocomposite is a well-organized antimicrobial material for different advanced domains.

Changes in Chemical and Thermal Properties of Bamboo after Delignification Treatment

Bamboo delignification is a common method for studying its functional value-added applications. In this study, bamboo samples were delignified by treatment with sodium chlorite. The effects of this treatment on the bamboo’s microstructure, surface chemical composition, and pyrolysis behaviour were evaluated. Field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were conducted to evaluate these parameters. The FTIR results demonstrated that the lignin peak decreased or disappeared, and some hemicellulose peaks decreased, indicating that sodium chlorite treatment effectively removed lignin and partly decomposed hemicellulose, although cellulose was less affected. The XPS results showed that, after treatment, the oxygen-to-carbon atomic ratio of delignified bamboo increased from 0.34 to 0.45, indicating a lack of lignin. XRD revealed increased crystallinity in delignified bamboo. Further pyrolysis analysis of treated and untreated bamboo showed that, although the pyrolysis stage of the delignified bamboo did not change, the maximum thermal degradation rate (R_max) and its corresponding temperature (from 353.78 to 315.62 °C) decreased significantly, indicating that the pyrolysis intensity of the bamboo was weakened after delignification. Overall, this study showed that delignified bamboo develops loose surfaces, increased pores, and noticeable fibres, indicating that alkali-treated bamboo has promising application potential due to its novel and specific functionalities.