Search Results (37)

With a growing demand for renewable resources in high-performance materials, sustainable methods are preferred for their lower environmental impact and alignment with circular economy principles. Among these, enzymatic hydrolysis remains relatively underexplored yet shows strong potential for cellulose fibrillation, offering a promising route that may lower energy requirements by minimizing the need for extensive refining compared to conventional mechanical or chemical approaches. In this study, enzyme cocktails rich in cellulase and xylanase were applied to three industrial pulps, sulphite, bleached Kraft eucalyptus and thermomechanical pine, to produce high-performance cellulose pulps. Treatments were carried out using varying enzyme loads (5–40 filter paper units per gram of dry pulp, FPU/gdp) and reaction times (1–16 h). The resulting chemical composition, structural morphology, and physical–mechanical properties were systematically evaluated. The findings revealed that pulp composition strongly influenced enzymatic treatment, affecting surface fibrillation, fibre aggregation, swelling, and fibre shortening. Under optimized conditions, enzymatic pretreatment significantly enhanced paper performance, with improvements in tensile strength, air permeability, hydrophobicity, and internal bonding. Overall, enzymatic hydrolysis represents a sustainable solution and a strategy which could reduce energy expenditures to high-performance cellulose pulps, suitable as reinforcing fibres in packaging applications. Full article

Cellulose-based paper products derived from agro-industrial waste have attracted considerable interest due to their potential in sustainable material development. In this study, bacterial cellulose (BC) residue from the food and beverage industry was employed as a reinforcing agent to fabricate high-performance paper composites by blending with eucalyptus pulp (EP) at various ratios and basis weights. These papers were coated with a cationic modified starch solution (MS) using a rod coater, followed by hot pressing. Mechanical strengths (TAPPI Standard), water resistance (Cobb test and water contact angle), and air permeability (ASTM D737) were evaluated to assess material performance. The results showed that incorporating 50 wt% BC produced paper with outstanding mechanical performance, characterized by a high tensile index and excellent tear resistance. The application of the MS coating significantly boosted water resistance and air barrier performance, underscoring the effectiveness of this approach in creating high-performance paper materials. The resulting coated composites demonstrated excellent mechanical strength and barrier properties, positioning them as promising candidates for filtration applications such as personal protective face mask membranes. Full article

Oil-contaminated wastewater represents a major source of industrial pollution, posing significant risks to both the environment and human health. Traditional oil–water separation methods, including gravity separation, centrifugal separation, and air flotation, are limited by their processing efficiency and scope of applicability. In recent years, innovative oil–water separation technologies have gained considerable attention, particularly those utilizing adsorption, filtration, and membrane separation, owing to their high efficiency and environmental sustainability. Separation materials derived from biomass substrates—such as cellulose, chitosan, and lignin—along with metal-based membranes and polymeric filters, have shown remarkable performance. This is especially true for superhydrophobic/superoleophilic and stimuli-responsive materials, which excel in separating complex emulsified oil systems. This paper provides a comprehensive overview of the strengths and limitations of current separation technologies and explores the potential applications of multifunctional materials in treating oil-contaminated wastewater, offering both theoretical insights and practical guidance for advancing green, efficient oil–water separation solutions. Full article

As a renewable and degradable biomass material, cellulose diacetate (CDA) has significant development potential and has gained widespread interest from researchers. However, its poor thermal stability at high temperatures limits its practical use in the extrusion process and restricts its applications in other fields, such as high-heat airflow filters, battery separators and special textile materials. To enhance the thermal stability of CDA, three heat-resistance additives, i.e., polyphenylene sulfide (PPS), polycarbonate (PC) and polyimide (PI), were introduced to synthesize PPS/CDA, PC/CDA and PI/CDA composite materials through melt extrusion. The incorporation of three heat-resistant additives increased the glass transition temperature (T_g), initial melting temperature (T_mⁱ) and final melting temperature (T_m^f) of the composites, and it reduced the heat loss at 195 °C. After conducting the isothermal thermogravimetry test for 3 h at 215 °C in an air atmosphere, the weight loss of PPS/CDA, PC/CDA and PI/CDA composites was 4.6%, 4.1% and 3.7%, respectively, which was 5.1% lower than that of pure CDA. Morphology characterization tests using a 3D digital microscope and a field emission scanning electron microscope (FESEM) revealed the compatibility order with CDA as the following: PC > PPS > PI. Additionally, Fourier transform infrared spectroscopy (FT–IR) disclosed that hydrogen bonds were formed between heat-resistant additives and CDA molecules, and the carbonyl groups in CDA showed conjugation and hyperconjugation effects with the benzene rings in the additives. Therefore, the enhanced thermal stability of CDA composites can be attributed to the molecular entanglement and crosslinking between additives and CDA molecules. Full article

Air filters are crucial components of building ventilation systems. Compared to conventional air filter media like glass fibers and melt-blown fibers, electrospinning membranes are more efficient for capturing various pollutants due to the smaller pores present on the structure. In this paper, activated carbon filters were prepared with eco-friendly polylactic acid (PLA) and microcrystalline cellulose (MCC) using electrospinning to obtain a high-quality factor (QF) fibrous mat for aerosol particle matter (PM) filtration and volatile organic compounds (VOCs) adsorption. Several configurations of the final membranes were investigated and tested for fiber morphology and air filtration performance. Filtering efficiency and adsorption properties were evaluated in a real-scale room by measuring the particle penetration of the newly synthesized and commercial filters against neutralized aerosol particles (3% NaCl aqueous solution) and VOCs (methyl ethyl ketone). The calculated depolluting efficiencies were up to 98% in terms of PM and 55% for VOCs abatement, respectively. Our results indicate that the proposed hybrid membranes represent promising materials for highly efficient and sustainable air filters for home application systems. Full article

Zeolitic imidazolate framework-8 (ZIF-8) is a highly promising material for carbon dioxide (CO₂) capture, thanks to its large surface area, high porosity, and selective adsorption properties, making it a strong alternative to conventional systems like monoethanolamine (MEA). The novelty of this work lies in the development of a ZIF-8-based cellulose air filter (ZCAF), produced using a rapid synthesis method combined with kraft pulping, enabling efficient integration of ZIF-8 nanoparticles into a cellulose matrix. This approach leverages the hydrophobic nature and large surface area of ZIF-8, along with the properties of softwood kraft pulp, to enhance CO₂ adsorption. Characterization through scanning electron microscopy (SEM) confirmed the rhombic dodecahedron morphology of ZIF-8, while energy-dispersive X-ray analysis verified its elemental composition. CO₂ adsorption tests using a Gasboard-3000P analyzer showed a 41% increase in CO₂ loading for ZIF-8 and a 22% increase for ZCAF compared with MEA. These results highlight the ZCAF’s potential to advance air filtration and gas separation technologies, offering sustainable solutions to global CO₂ capture challenges. Full article

Electrostatic fields are crucial for achieving the highly efficient filtration of airborne pollutants. However, the dissipation of static charges over time, especially under humid conditions, limits their practical application. In this study, we present a self-charging air filter (SAF) powered by a triboelectric nanogenerator (TENG). This SAF is integrated into a commercial mask, termed SAFM, which can effectively capture and degrade airborne pollutants without requiring an external power source. By leveraging the triboelectric effect during breathing, the TENG within the SAFM continuously replenishes static charges, maintaining the triboelectric field. The system employs a cellulose aerogel/Ti₃C₂T_x composite as the electron donor and an esterified cellulose-based electrospun nanofiber as the electron acceptor. Remarkably, the triboelectric field significantly enhances filtration performance, with the SAF achieving up to 95.7% filtration efficiency for particulate matter as small as 0.3 μm. This work underscores the potential of TENG-powered triboelectric fields in the development of multifunctional, human-machine interactive facemasks. Full article

The purpose of this study was to empirically evaluate the performance of fibrous materials that meet the criteria for inlet air filtration in internal combustion engines. The characteristics of filtration efficiency and accuracy, as well as the characteristics of flow resistance, were determined based on the mass of dust accumulated in the filter bed during the filtration process. Single-layer filter materials tested included cellulose, polyester, and glass microfiber. Multilayer filter media such as cellulose–polyester–nanofibers and cellulose–polyester were also examined. A new composite filter bed—consisting of polyester, glass microfiber, and cellulose—and its filtration characteristics were evaluated. Utilizing specific air filtration quality factors, it was demonstrated that the composite is characterized by high pre-filtration efficiency (99.98%), a short pre-filtration period (q_s = 4.21%), high accuracy (d_pmax = 1.5–3 µm) for the entire lifespan of the filter, and a 60–250% higher dust absorption coefficient compared to the other tested materials. A filtration composite bed constructed from a group of materials with different filtration parameters can be, due to its high filtration efficiency, accuracy, and dust absorption, an excellent filter material for engine intake air. The composite’s filtration parameters will depend on the type of filter layers and their order relative to the aerosol flow. This paper presents a methodology for the selection and testing of various filter materials. Full article

Considering the high demand for air quality, the development of biomass-based air filtration membranes with high air filtration efficiency and good stability is an urgent task. In this work, polyvinyl alcohol (PVA), gelatin (GA), and cellulose nanocrystals (CNC) were mixed and prepared into a membrane through an electrospinning method for air filtration. After a hydrophobic modification, the modified PVA/GA/CNC composite membrane showed excellent filtration efficiency for PM2.5 (97.65%) through the internal three-dimensional structure barrier and the electrostatic capture effect of the CNC with a negative charge, as well as a low-pressure drop (only 50 Pa). In addition, the modified PVA/GA/CNC composite membrane had good mechanical properties (maximum tensile fracture rate of 78.3%) and high stability (air filtration efficiency of above 90% after five wash-filter cycles and a high-temperature treatment at 200 °C). It is worth noting that the whole preparation process is completed without organic solvents, putting forward a new strategy for the construction of green air filtration membranes. Full article

A cellulose-based triboelectric nanogenerator (TENG) with fiber–wave–arch structure was prepared through a multi-fluid electrospinning process for air filtration and wind sensing. The TENG is composed of a cellulose nanocrystals (CNC)/zein membrane and a cyanoethyl cellulose (CEC)/polyvinylidene fluoride (PVDF) membrane. The results show that the addition of CEC improves the output performance and filterability of TENG. At the same time, the reduced diameter and high roughness of CEC/PVDF nanofibers improve the output performance of the TENG. The TENG with a 6 wt% CEC/PVDF solution concentration has the highest output performance with a short-circuit current of 3.30 μA and an open-circuit voltage of 10.01 V. The particle filtration of 12 wt% CEC/PVDF TENG is the best, showing an efficiency of 98.84% and a pressure drop of 50 Pa. The TENG also has a good formaldehyde filtration capability with an efficiency of 92% at 0.25 mg/m³. The TENG shows great potential in self-powered sensor applications. Full article

As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size. Full article

Since the late 2010-s and early 2020s, people around the world have not only encountered the pandemic crisis, but also in some places, they have had to deal with serious levels of air pollution. Personal protective equipment is essential to protect from microorganisms or fine particulate matter. Consequently, this study aimed to develop a silk face covering that could meet the international requirements with the addition of having an antibacterial property. The developed silk face covering consisted of three layers; the outer layer was water-repellent mulberry silk, the inner layer was oil-repellent eri silk, while the middle layer was cotton fabric coated with biosynthesized silver nanoparticles from mangosteen peels mixed with Andrographis paniculata extract. A biodegradable bacterial cellulose filter made of nata de coco waste was also prepared to improve filtration efficiency. It was found that the silver nanoparticles extracted from mangosteen peel and Andrographis paniculata inhibited S. aureus and E. coli by more than 99.9%, even after 20 washing cycles. The performance properties of the silk barrier face covering met Level I of the ASTM F3502-2021 standard, as well as being comfortable for public use. Full article

A thin, lightweight and flexible electromagnetic interference (EMI) shielding paper composite is an urgent need for modern military confrontations. Herein, a sandwich-structured EMI shielding paper composite with an easy pavement consisting of a filter paper layer, middle AgNWs/MXene layer, and polyvinyl butyral (PVB) layer was constructed by vacuum-assisted filtration, spraying and air-drying. The middle AgNWs/MXene compound endowed the filter paper with excellent electrical conductivity (166 S cm⁻¹) and the fabricated filter paper–AgNWs/MXene–PVB composite exhibits superior EMI shielding (30 dB) with a 141 μm thickness. Remarkably, the specific EMI shielding effectiveness (SSE/t) of the filter paper–AgNWs/MXene–PVB composite reached 13,000 dB cm² g⁻¹ within the X-band frequency range. This value represents one of the highest reported for cellulose-based EMI shielding materials. Therefore, our sandwich-structured filter paper composite with superior EMI shielding performance can be used in the medical and military fields. Full article

Outdoor and indoor atmospheric pollution is one of the major problems that humanity continues to face. As a mitigation pathway, numerous technologies have been developed for air purification, including the use of fibrous filters. In this study, the particle capture efficiencies and pressure drops of air filters manufactured with cellulose pulp extracted from banana pseudostems were studied across three particle size ranges (PM10, PM2.5, and PM1). Two pretreatments were applied, alkaline with soda-antraquinone (alkali-treated pulp) and a subsequent bleaching process (bleached pulp), and four manufacturing processes were tested: crushing, freeze-drying, vacuum filtration, and pressing. In addition, a study varying filter grammage (70, 100, and 160 g·m⁻²) and pressing pressures (2, 4, 6, and 8 t) was also performed. After conducting these particle tests, the filter manufactured with bleached pulp, having a grammage of 160 g·m⁻² and pressed at 4 t, was deemed the optimal individual solution. It demonstrated high particle retention efficiencies across all particle size ranges (with values exceeding 80%), a moderate pressure drop below 1000 Pa, and high thermal stability (degradation above 220 °C). However, combining freeze-drying and two-ton pressing processes yielded improved results (83% for the smallest particles and 89% for others) with approximately half the pressure drop. Based on these results, this study stands as a noteworthy contribution to waste valorization and the advancement of environmentally friendly materials for particle air filters. This is achieved through the adoption of simple and cost-effective technology, coupled with the utilization of 100% natural agricultural waste as the primary manufacturing material. Full article

Addressing urban air pollution is a pressing challenge, prompting the exploration of mitigation strategies such as urban greening. However, certain innovative greening approaches, while promising, may inadvertently incorporate unsustainable elements that undermine their eco-friendly philosophy. In this context, our research focuses on addressing the replacement of a petroleum-based filter substrate in an existing ‘green’ outdoor air purification system that utilizes ‘moss filters’, known as a ‘moss wall’. This initiative is driven by concerns about microplastic leakage from the substrate and the need to optimize the moss wall system in terms of circularity. This preliminary study presents a crucial first step, aiming to assess the feasibility of developing a circular, bio-based plate as a replacement for the existing microfiber filter substrate. The focus is on the potential of this plate to recycle moss from the system itself as raw material, ensuring structural integrity and the ability to support its own weight. To achieve this goal, a series of controlled experiments were conducted in a laboratory setting using cellulose, corn starch, and metakaolin binders. Our findings indicated that cellulose was crucial for the structural integrity, starch significantly enhanced the sample strength, and metakaolin improved the water resistance. These insights culminated in the creation of a laboratory-scale moss-based composite prototype, with moss constituting more than half of the total mass. This prototype demonstrated promising results as a starting point for a more environmentally friendly and bio-based moss wall substrate. Subsequent research efforts will concentrate on optimizing the binder and fiber composition, evaluating and improving the bioreceptivity and filter properties, conducting outdoor testing, and scaling up the prototype for practical implementation. Full article