Nanofibrillated celluloses (NFCs) have recently drawn much attention because of their exceptional physicochemical properties. However, the existing preparation procedures either produce low yields or severely degrade the cellulose and, moreover, are not energy efficient. The purpose of this study was to develop a novel process using ultrasonic homogenization to isolate fibrils from bamboo fiber (BF) with the assistance of negatively charged entities. The obtained samples were characterized by the degree of substitution (DS) of carboxymethyl, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis, and transmission electron microscopy (TEM). The results showed that an NFC yield could be obtained above 70% through this route. The enzyme hydrolysis could enhance the surface charge of the fiber, and mechanical activation facilitates an increase in the DS. The disintegrating efficiency of the cellulose fibrils significantly depended on the input power of ultrasonication and the DS. FT-IR spectra confirmed the occurrence of the carboxymethylation reaction based on the appearance of the characteristic signal for the carboxyl group. From XRD analysis, it was observed that the presence of the carboxyl groups makes the isolation more efficient attributed to the ionic repulsion between the carboxylate groups of the cellulose chains.
The freshness and safety of fruits and vegetables is important in our daily life. Paper products are often used for shipping, wrapping, and decoration in the retail for fruits and vegetables. When these paper products are modified with active substances, they can offer additional functions other than just packaging. Thus, introducing 1-methylcyclopropene (1-MCP) into paper products can impart a preservation function for fruits and vegetables. 1-MCP is an excellent and eco-friendly inhibitor of ethylene that can effectively retard the ripening of fruits and vegetables. This article reviews the ripening process induced by ethylene, the inhibition mechanism of 1-MCP, and the existing technologies and products for 1-MCP utilization. Novel active paper packaging products via the use of encapsulated 1-MCP complexes may have a great potential for commercialization. Such packaging containing 1-MCP active paper could be effective in prolonging the shelf-life and improving the quality of the product during the storage, shipping process, and retail market, and can be attractive economically, socially, and environmentally.
Graphitic carbon nitride (g‐C3N4) is traditionally obtained by thermal polycondensation of nitrogen‐rich organic nonionic precursors. Herein, we provide a new and simple strategy for the synthesis of g‐C3N4 through direct thermal condensation of single protic guanidine salts with various anions. The thermal condensation process, and the structure and photophysical properties (optical properties, thermal stabilities, morphology and porosity, and photocatalytic activity) of the obtained g‐C3N4 materials are investigated intensively through thermogravimetric analysis, powder X‐ray diffraction, X‐ray photoelectron spectroscopy, UV/Vis diffuse reflectance spectroscopy, nitrogen adsorption isotherms, and photodegradation of Rhodamine B. The results reveal that during thermal condensation, the nitrogen‐rich basic core in the guanidine salts serves as a carbon and nitrogen source to form the skeleton of g‐C3N4, and the counter anions mediate the thermal condensation in situ and modify slightly the structure and properties of g‐C3N4, even though they are not incorporated into the final structure. Among all g‐C3N4 materials, including the pristine g‐C3N4 from melamine, the g‐C3N4 derived from guanidine thiocyanate exhibits a high activity toward the photocatalytic degradation of Rhodamine B dye because of its relatively high surface area, enhanced absorption, small bandgap, and low photoluminescence intensity.
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