Developing fluorine-free superhydrophobic and biodegradable materials for oil/water separation has already become an irresistible trend. In this paper, we designed two biopolymer oil/water separation routes based on cellulose stearoyl ester (CSE), which was obtained via the acylation reaction between dissolving pulp and stearoyl chloride homogeneously. The CSE showed a superhydrophobic property, which could selectively adsorb oil from the oil/water mixture. Additionally, the CSE was emulsified with an oxidized starch (OS) solution, and the resulting latex was used to impregnate commercial, filter base paper, finally obtaining a hydrophobic and oleophilic membrane. The SEM revealed the membrane had hierarchical micro/nanostructures, while the water contact angle indicated the low surface energy of the membrane, all of which were attributed to the CSE. The membrane had high strength and long durability due to the addition of OS/CSE, and the separation efficiency was more than 99% even after ten repeated uses.
Due to great advantages, such as simple operation, high porosity, and good fiber continuity, the working principle and research progress of electrospinning technology was studied and polyvinyl alcohol (PVOH) nanofibers were prepared via this process. Air filter paper was used as the receiving substrate to prepare electrospun nano air filter paper (NAFP). The PVOH concentration, static voltage, and receiving distance, were tested to explore the influence of spinning parameters on the filtration performance. Further, the microfiber morphology of the electrospun NAFP was observed. The performance of filter paper, including air permeability, pore size, initial resistance, filtration efficiency, and dust retention, were tested. The results showed that the electrospun NAFP had better filtration performance compared to the air filter paper, and simultaneously they had lower initial resistance and higher precision filtration efficiency. The nanofiber influenced the surface of the air filter paper, as it sharply reduced the pore size. When the spinning condition was 10%, 21 kV, and 15 cm, the pore size decreased approximately 0.6 times of the original, which meant the electrospun NAFP could capture particles ≥ 0.2 μm in size. Finally, after three repeated uses, the good filtration performance was maintained.
In this paper, a simple method for hydrophobic modification of polyvinyl alcohol (PVA) was found. Using N-methylpyrrolidone as solvent, PVA was esterified with stearyl chloride without catalyst. The modified hydrophobic polyvinyl alcohol (MPVA) was well verified by FT-IR and XRD. Using air filter paper as receiving substrate and MPVA as spinning solution, MPVA air filter paper with water resistance and high filtration performance was prepared, and hydrophilic PVA air filter paper was prepared as controlled sample. SEM was used to observe the fiber morphology on the surface of the two composite filter papers. The contact angle of hydrophobic MPVA air filter paper (25:3) was 121.9°, and the filtration efficiency was increased to 99.9955 % and the filter initial resistance increased to 90 Pa.
Countries are duly focusing more on biomass resources because of the increasing oil crisis. Owing to their excellent properties, such as natural characteristics, good mechanical performance, and outstanding chemical properties, cellulose-based materials are highly valued as promising bioderived nanomaterials, especially bacterial cellulose (BC). The main advantage lies in eliminating the problem of removing lignin and hemicellulose from woody cellulose. Moreover, the use of BC reduces the consumption of wood, the excessive use of which aggravates global warming.Herein, we summarize the applications of BC composites in filter, medical, and conductive materials, and other fields. This review contributes to further expand the applications of this renewable polymer.
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