In this work, hydrogels composed of cellulose nanofibril (CNF) and sodium alginate (SA) were prepared as a pH-responsive release system by controlling the amount of CNF and SA. Scanning electron microscopy, thermogravimetric analysis, and swelling rate methods were used to characterize. The results showed that when the mass ratio of CNF to SA was 2:1, CNF/SA hydrogels with better morphology were obtained. Due to the deprotonation or protonation of calcium alginate, as the pH changing from 1.5 to 11.0, the swelling ratio increased from 7 times to 19 times compared with its dry weight. The

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The purpose of this study is to prepare lemon essential oil (LEO) microcapsules by ionic gelation method using chitosan (CS) and cellulose nanocrystals (CNC) as the wall material. The influence of the concentration of CS and CNC and the pH of CS solution on the encapsulation efficiency (EE) of microcapsules was studied. Taking the EE as an indicator, and according to the single‐factor test results, a three‐factor three‐level response surface methodology was designed. The best process conditions of CS/CNC‐LEO microcapsules to get the maximum EE of 89.98% were as follows: pH of CS was 3.44, and the concentration of CS, CNC were 2, 3.52 g/L. The microcapsules prepared under these conditions were smooth and rounded spherical. The diameters of unembedded and embedded LEO microcapsules ranged from 541.2–732.9 to 1014.5–1528.7 nm, respectively. Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis were used to analyze the characteristics of the microcapsules. There were two periods in vitro release studies of CS/CNC‐LEO microcapsules: sudden release and slow release of essential oils.

Metal nanoparticles play an essential role in catalyzing the degradation of dyes in industrial wastewater. In order to improve the catalytic reduction and discoloration performance of silver nanoparticles (Ag NPs) to cationic dyes and facilitate recovery, we report an improved method to prepare cellulose nanofibrils/polyvinyl alcohol (CNF/PVA) porous composite hydrogel and use it to support metal nanoparticles. Silver ions were reduced to Ag NPs by the in situ reduction method after being adsorbed on the surface of the hydrogel by electrostatic adsorption, and the maximum adsorption capacity was about 136.4 mg/g. The obtained CNF/PVA/Ag NPs (CPA) composite hydrogel was characterized by scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and energy dispersive spectroscopy. Furthermore, we demonstrate the efficient utilization of composite hydrogel as a container in the discoloration of methylene blue (cationic dye) and methyl orange (cationic dye) in the presence of NaBH 4 . The hydrogel was quickly recovered and reused without a decrease in activity for five cycles. It showed fantastic potential in water resources protection and catalytic application.