Behavior of toluene adsorption on activated carbon nanofibers prepared by electrospinning of a polyacrylonitrile-cellulose acetate blending solution

Facile Coaxial Electrospinning Synthesis of Polyacrylonitrile/Cellulose Acetate Nanofiber Membrane for Oil-Water Separations

Oil-contaminated water and industrial oily wastewater discharges have adversely affected aquatic ecosystems and human safety. Membrane separation technology offers a promising solution for effective oil-water separation. Thus, a membrane with high surface area, hydrophilic-oleophobic properties, and stability is a promising candidate. Electrospinning, a straightforward and efficient process, produces highly porous polymer-based membranes with a vast surface area and stability. The main objective of this study is to produce hydrophilic-oleophobic polyacrylonitrile (PAN) and cellulose acetate (CA) nanofibers using core-shell electrospinning. Incorporating CA into the shell of the nanofibers enhances the wettability. The core PAN polymer improves the electrospinning process and contributes to the hydrophilicity-oleophobicity of the produced nanofibers. The PAN/CA nanofibers were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, and surface-wetting behavior. The resulting PAN/cellulose nanofibers exhibited significantly improved surface-wetting properties, demonstrating super-hydrophilicity and underwater superoleophobicity, making them a promising choice for oil-water separation. Various oils, including gasoline, diesel, toluene, xylene, and benzene, were employed in the preparation of oil-water mixture solutions. The utilization of PAN/CA nanofibers as a substrate proved to be highly efficient, confirming exceptional separation efficiency, remarkable stability, and prolonged durability. The current work introduces an innovative single-step fabrication method of composite nanofibers, specially designed for efficient oil-water separation. This technology exhibits significant promise for deployment in challenging situations, offering excellent reusability and a remarkable separation efficiency of nearly 99.9%.

Cellulose for the Production of Air-Filtering Systems: A Critical Review

The control of airborne contaminants is of great interest in improving air quality, which has deteriorated more and more in recent years due to strong industrial growth. In the last decades, cellulose has been largely proposed as suitable feedstock to build up eco-friendly materials for a wide range of applications. Herein, the issue regarding the use of cellulose to develop air-filtering systems is addressed. The review covers different cellulose-based solutions, ranging from aerogels and foams to membranes and films, and to composites, considering either particulate filtration (PM₁₀, PM_2.5, and PM_0.3) or gas and water permeation. The proposed solutions were evaluated on the bases of their quality factor (QF), whose high value (at least of 0.01 Pa^-1 referred to commercial HEPA (high-efficiency particulate air) filters) guarantees the best compromise between high filtration efficiency (>99%) and low pressure drop (<1 kPa/g). To face this aspect, we first analyzed the different morphological aspects which can improve the final filtration performance, outlining the importance on using nanofibers not only to increase surface area and to modulate porosity in final solutions, but also as reinforcement of filters made of different materials. Besides the description of technological approaches to improve the mechanical filtration, selected examples show the importance of the chemical interaction, promoted by the introduction of active functional groups on cellulose (nano)fibers backbone, to improve filtration efficiency without reducing filter porosity.

Synthesis and applications of carbon nanofibers: a review

Carbon nanofibers (CNFs) have shown great potential in multiple applications. Their versatility is derived from the possibility of tuning their physical and chemical properties. CNFs can be synthesized using two main methods: the catalytic decomposition of carbon precursors or the electrospinning and carbonization of polymers. The most appropriate method relies on the desired characteristics of the CNFs. Some of their applications include the synthesis of catalysts and catalytic supports, as electrodes for fuel cell devices, in hydrogen storage systems, and in functional nanocomposites. In this review, recent advances in the synthesis and potential applications of CNFs are examined.

Alkali promoted the adsorption of toluene by adjusting the surface properties of lignin-derived carbon fibers

The lignin-based carbon fibers were prepared by electrospinning followed by stabilization, carbonization, and activation (i.e., steam activation, one-step KOH activation, and metal activation). The effect of carbonization temperature on prepared carbon fibers (CFs) was investigated. As a result, 800 °C is the most suitable carbonization temperature because the prepared carbon fibers possess greater specific surface area and pore volume. With the help of various characterization methods, the structural characteristics of the activated carbon fibers (ACFs) prepared by the three activation methods and the adsorption performance of toluene were compared. It was observed that the activated carbon fibers prepared by KOH one-step activation method (ACFK) exhibited higher specific surface area (1147.16 m²/g) and greater toluene adsorption (463 mg/g). Particularly, abundant microporous structures and surface functional groups play a vital role in the adsorption process. Further, the adsorption performance of toluene onto ACFK was further investigated in a gas-phase dynamic adsorption system and the results showed that ACFK has great potential application in adsorption of volatile organic compounds.

A Hybrid Reactor System Comprised of Non-Thermal Plasma and Mn/Natural Zeolite for the Removal of Acetaldehyde from Food Waste

The degradation of low concentrations of acetaldehyde while using a non-thermal plasma (NTP)/catalyst hybrid reactor system was investigated while using humidified air at ambient temperature. A series of highly active manganese-impregnated natural zeolite (Mn/NZ) catalysts were synthesized by the incipient wetness method using sonication. The Mn/NZ catalysts were analyzed by Brunauer-Emmett-Teller surface area measurements and X-ray photoelectron spectroscopy. The Mn/NZ catalyst located at the downstream of a dc corona was used for the decomposition of ozone and acetaldehyde. The decomposition efficiency of ozone and acetaldehyde was increased significantly using the Mn/NZ catalyst with NTP. Among the various types of Mn/NZ catalysts with different Mn contents, the 10 wt.% Mn/NZ catalyst under the NTP resulted the highest ozone and acetaldehyde removal efficiency, almost 100% within 5 min. Moreover, this high efficiency was maintained for 15 h. The main reason for the high catalytic activity and stability was attributed to the high dispersion of Mn on the NZ made by the appropriate impregnation method using sonication. This system is expected to be efficient to decompose a wide range of volatile organic compounds with low concentrations.