Characterization of Porous Structures of Cellulose Nanofibrils Loaded with Salicylic Acid

Abstract

Bleached and unbleached pulp fibers were treated with 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) mediated oxidation to obtain cellulose nanofibrils (CNFs). The resulting bleached and unbleached CNFs were mixed with salicylic acid (0, 5, 10, 20 wt%) before casting and freeze-drying or 3D-printing. A series of methods were tested and implemented to characterize the CNF materials and the porous structures loaded with salicylic acid. The CNFs were characterized with atomic force microscopy and laser profilometry, and release of salicylic acid was quantified with UV-visible absorbance spectroscopy, conductivity measurements, and inductive coupled plasma mass spectrometry (ICP-MS). Fourier-transform infrared spectroscopy (FTIR) complemented the analyses. Herein, we show that aerogels of bleached CNFs yield a greater release of salicylic acid, compared to CNF obtained from unbleached pulp. The results suggest that biodegradable constructs of CNFs can be loaded with a plant hormone that is released slowly over time, which may find uses in small scale agricultural applications and for the private home market.

The Effects of Unbleached and Bleached Nanocellulose on the Thermal and Flammability of Polypropylene-Reinforced Kenaf Core Hybrid Polymer Bionanocomposites

“…The early thermal degradation stage in this study occurred at 100–111.2 °C, which contributed to 5% of the total weight loss. This phenomenon corresponded to the evaporation of water molecules [ 13 , 28 , 29 , 30 ]. It includes three types of water in fiber, namely free water, loosely-bonded water and chemically-bonded water, which were lost due to the overlapping of three different processes, as recorded by the thermogravimetric curve, as shown in Figure 3 a [ 57 ].…”

“…Apart from the success of natural fibers to enhance the mechanical properties of the composites, the production of new natural fiber-based materials has opened up a strong opportunity, especially in the industrial sector. Nanocellulose is one of the products extracted from natural fibers, which possesses high performance with tailored mechanical and physical properties, making it the most attractive renewable material for advanced applications [ 29 ]. Nanocellulose is generally referring to cellulosic extracts with a diameter of <100 nm [ 30 , 31 , 32 , 33 ].…”

Separation and Characterization of Cellulose Fibers from Cannabis Bast Using Foamed Nickel by Cathodic Electro-Fenton Oxidation Strategy

“…A significant absorption difference of 2850 cm −1 (-CH 2 symmetric stretching vibration) is evident, and the absorption peak of the treated fiber almost completely disappeared compared with the untreated fiber that used different degumming treatment methods. The range of 3000 cm −1 to 3600 cm −1 corresponds to -OH tensile vibration, which is mainly attributed to the structure of cellulose and lignin [ 30 ]. According to different degumming methods, the relative strength decreases at 3000–3600 cm −1 , which indicates that the hydroxyl groups are significantly reduced and removed.…”

Nanocellulose by Ammonium Persulfate Oxidation: An Alternative to TEMPO-Mediated Oxidation

“…Chemical processes for oxidizing cellulose, such as a TEMPO-mediated one, to nanofibers require a lignin-free biomass to prevent increased consumption of reactants. 42,43 The insoluble lignin content of unbleached pulps consumes hypochlorite in TEMPO-mediated oxidation reactions. 44 A multistep process is required to remove the lignin.…”

“…The formation of peroxide under acidic conditions, eq , leads to oxidation of lignin, which may be improved through the possible formation of peroxymonosulfate in secondary reactions with sulfate radicals. , Evaluation of the ammonium persulfate must consider the effect of lignin on the response to treatment. Chemical processes for oxidizing cellulose, such as a TEMPO-mediated one, to nanofibers require a lignin-free biomass to prevent increased consumption of reactants. , The insoluble lignin content of unbleached pulps consumes hypochlorite in TEMPO-mediated oxidation reactions . A multistep process is required to remove the lignin.…”