Hydrophilic Fibers Research Articles

Tailoring crack width control of LC3-based engineered cementitious composites (ECC) via fiber hybridization: From micromechanics design to macro investigation

As a class of strain-hardening cement-based material, Engineered Cementitious Composites (ECC) feature high tensile ductility and multiple cracking. However, ECCs reinforced with hydrophobic fibers attain high ductility but also exhibit larger crack widths caused by the weak bonding of the fiber/matrix interface, attenuating the durability potential of resulting infrastructures. This research aims at tailoring the crack width control ability of ECC through hybridizing hydrophilic PVA and hydrophobic PP fiber. A systematic design procedure was proposed based on the micromechanical analysis with a multi-scale investigation. Experimental results verified the hypothesized composite ductility enhancement by PP fiber and strength enhancement and crack width reduction by PVA fiber. Tight crack width of 50 μm at 2 % tensile strain can be achieved by a fiber hybridization ratio of 1:1 to ensure extreme durability. Changes in the microstructure of the matrix, associated with fresh property alteration due to fiber hybridization, were captured by micro CT scanning. Finally, the trade-off between mechanical performance, durability, and material sustainability was investigated for optimal material design. This research demonstrates that hybridizing PVA fiber with PP fiber holds promise to enhance material sustainability while maintaining the advantageous characteristics of ductile ECC and tight crack width for extreme durability.

Improved Thermal and Mechanical Properties of Kenaf Fiber/ABS Polymer Composites via Resin Coating Treatment

In developing natural fiber composites (biocomposites), compatibility between natural cellulosic fibers and polymers has always created serious challenges, reducing performance. This study focused on applying a novel approach using epoxy resin as a coating medium to enhance the properties of the fibers and the interface between the hydrophobic polymer and the hydrophilic natural fiber. 10 wt% of uncoated kenaf fibers (KF) and coated kenaf (CKF) fibers were compounded with acrylonitrile butadiene styrene (ABS) thermoplastic polymer in a twin-screw extruder at an optimized temperature of 220°C under the same processing conditions. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) examined the coated and uncoated fibers' physicochemical compositions and surface properties. The developed composites' thermal, mechanical, and microstructural characteristics were also examined, and the results revealed that the CKF/ABS composites had better interfacial bonding and mechanical characteristics than the uncoated KF/ABS composite. Coating natural fibers with epoxy resin is a novel technique for improving interfaces and developing environmentally friendly composites from natural sources.

Green biodegradable dielectric material made from PLA and electron beam irradiated luffa cylindrica fiber: devices for a sustainable future.

The growing prevalence of polymer-based plastics in the environment is an imminent risk to the natural world. As an immediate consequence of this, extensive research has been launched over the course of the past few decades in an effort to reduce the damage that manmade plastics cause to the natural environment. The current study attempts to explore the biodegradability of polylactic acid (PLA), a bio-compatible plastic, by incorporating small amount of electron beam irradiated natural fibers (2 to 10%) derived from luffa cylindrica (LC) at varying irradiation doses (0.5 Gy, 1 Gy, and 2 Gy). Natural fiber surface treatment using electron beam irradiation is effective and environmentally friendly. The biodegradation of composites was studied for 90 days in sand, soil, compost, brackish water, fresh water, salt water, and bacterial and fungal conditions. Maximum decomposition was observed in the composite sample (PLA/10% wt of LC fiber at 2.0 Gy) at 15.42% and 4.73% in bacterial and soil environments. X-ray diffraction (XRD) and Raman spectroscopy validated the fiber and PLAs crystallinity and molecular interaction. The derivative thermo-gravimetric curve (DTGA) showed that electron beam irradiation removed moisture, hemicelluloses, and lignin from hydrophilic fibers. The incorporation of LC fibers into the bio-composites resulted in an increase in the glass transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc). Additionally, after LC fiber reinforcement, the composites' dielectric properties were enhanced.

Multi-Walled CNTs/BiVO4 Heterostructures for Solar-Driven Evaporation System and Efficient Photocatalytic Activity against Oxytetracycline.

Developing a sustainable environment requires addressing primitive water scarcity and water contamination. Antibiotics such as oxytetracycline (OTC) may accumulate in the environment and in the human body, increasing the risks to the ecosystem. The treatment of polluted water and the production of potable water can be achieved in a variety of ways, including photodegradation, solar distillation, and filtration. Freshwater supplies can be increased by implementing energy-efficient technologies for the production of clean water. Solar water evaporation combined with photocatalytic degradation and sterilization offers a promising avenue for integration into the clean water and energy production fields. The present study reports the synthesis of a 3D solar steam generator comprised of BiVO4 and carbon nanotubes (CNT) nanocomposite decorated over a cigarette filter as the light-to-heat conversion layer for solar steam generation. The BiVO4@CNT-based 3D solar evaporator over the hydrophilic cellulosic fibers of the cigarette filter endowed excellent evaporation rates (2.36 kg m-2 h-1) under 1 kW m-2 solar irradiation, owing to its superior hydrophilicity and broadband solar absorption (96%) equipped with localized heating at microscale thermal confinement optimized by the minimum thermal conductivity of the overall system. Furthermore, the BiVO4@CNT composite exhibited a heightened photo activity up to 83% of the photodegradation of oxytetracycline (OTC) antibiotic due to the inhibition of charge recombination from the industrial effluents. This approach transforms the water-energy nexus into a synergistic bond that offers opportunities to meet expected demand, rather than being competitive.

A hydrophilic Lignin-Based carbon fiber sizing agent assembled with CNTs towards strengthening epoxy resin

The sizing agent has attracted growing attention to improve the interfacial compatibility of carbon fiber reinforced epoxy resin composites (CF/EP), but suffered from poor interfacial adhesion and environmental problems. Here, a hydrophilic lignin-based sizing agent (OLBEDKC) with remarkable storage stability and sizing effect on CF was obtained by the modifying oxidized lignin rich in hydrophilic groups and compounding with carbon nanotubes (CNTs). After treatment with 2.5% OLBEDKC, the hairiness of the CF fabric was reduced by 73.5%, and the surface energy was increased by 43.7%. Moreover, the use of OLBEDKC in CF/EP composites can lead to an increase in their interlaminar shear strength (ILSS), interface shear strength (IFSS), flexural strength, and flexural modulus by 58.4%, 64.8%, 87.9%, and 24.6%, respectively, compared to those without sizing treatment. This increase is attributed to the π-π conjugation and hydrogen bonding among the OLBEDKC, CF, and EP. Furthermore, the mechanical interlocking between the sized CF and EP effectively enhances their interfacial strength. In summary, this study presents a promising and eco-friendly hydrophilic sizing agent based on lignin that possesses high storage stability and exhibits an excellent sizing effect for CF reinforced EP composites.

Photodegradation of MC-LR using a novel Au-decorated Ni metal-organic framework (Au/Ni-MOF)

Microcystins (MCs) are toxins produced by cyanobacteria commonly found in harmful algal blooms (HAB) occurring in many surface waters. Conventional methods for removing MC-LR such as membrane filtration and activated carbon are only phase change removal methods and are often expensive in operation and maintenance. It is urgent to develop a rapid, easy-to-use, and cost-effective method for the degradation of MC-LR. In this study, a novel Au-decorated Ni-metal-organic framework (Au/Ni-MOF) was newly developed on a hydrophilic carbon fiber paper (2 cm × 2 cm) using an air spraying method. The Au/Ni-MOF was then applied for the photodegradation of MC-LR in water under UV–Vis. The addition of Au onto the surface of the Ni-MOF resulted in a nearly fivefold enhancement in the reaction rate coefficient (k), reaching a value of 0.0599 min−1 for the photodegradation of MC-LR (initial concentration of 20 ppb). It was found that 94.2% of MC-LR removal was attributed to photodegradation, with the remaining 5.8% from adsorption. The rate coefficient of 20 ppb of MC-LR in the surface water sample (pH 6.0) was 0.06 min−1 likely due to the presence of other contaminates including scavenger agents within the sample which inhibits the degradation reaction of the MC-LR. Overall, this study demonstrated the potential for the novel Au/Ni-MOF to effectively reduce the concentration of the MC-LR toxin in the contaminated water.

Photodegradation modifies microplastic effects on soil properties and plant performance

Abstract Microplastics (MPs) in soil affect plant–soil systems depending on their shape and polymer type. However, previous research has not yet considered the effects of degraded plastics, which are the plastic materials actually present in the environment. We selected eight MPs representing different shapes (fibres, films and foams) and polymer types, and exposed them to UV‐C degradation. Each MP was mixed with soil at a concentration of 0.4% (w/w). The phytometer Daucus carota grew in each pot. At harvest, soil properties and plant biomass were measured. Photodegradation altered MP physical and chemical properties, impacting plant–soil systems. MP degradation effects on plant and soil were observed with fibres and foams, but there were negligible effects with films. The latter could be explained by the polymer structure of films and manufacturer's additives, potentially delaying their degradation. Degraded fibres increased soil respiration more than their non‐degraded counterparts, as photodegradation increased the positive effects of fibres on soil water retention. The emergence of oxygenated groups during degradation may have increased the hydrophilicity of fibres, enhancing their ability to retain water. Degraded foams increased soil respiration, which could be related to the possible leaching of organic substances with lower partition coefficients, which may promote soil microbial activity. In contrast, degraded foams decreased soil aggregation, likely as degradation produced larger holes increasing their permeability. Also, the increase in hydrophilic molecules could have decreased soil particle cohesiveness. Degraded fibres and foams increased shoot and root mass as a result of MP effects on soil properties. Photodegraded MPs affected root traits, which could be linked to MP effects on soil water status and plant coping strategies. Synthesis and applications. Photodegradation can intensify the effects that microplastics (MPs) have on plant–soil systems, which would have frequently been underestimated had we only worked with pristine MPs. Plastic companies, agricultural practitioners and researchers should consider that plastics are being degraded as they enter the soil. Policies should promote practices to minimize MP accumulation in soils and ensure their proper disposal.

ANALYSIS OF THE FLOW OF A FIBROUS SUSPENSION IN A GRINDING PLANT IN THE PRODUCTION OF FINE CELLULOSE

Of the various methods for obtaining microcrystalline cellulose (mechanical, chemical, thermomechanical, planting cellulose in powder form from its solutions), the most common is acid hydrolysis of cellulose. The difficulty of obtaining MCC from vegetable raw materials is that, in addition to cellulose, it contains in its composition such compounds as lignin, hemicelluloses, various extractive substances and an insignificant percentage of minerals. When grinding plant fibers in an aqueous medium, both a purely mechanical process of changing the size and shape of fibers and a colloidal chemical process called fiber hydration occurs. Mechanical phenomena are expressed in the shortening of fibers, their longitudinal splitting into fibrils, an increase in the outer surface and the number of free hydroxyl groups on their surface. The term hydration refers to colloidal chemical phenomena that begin with the swelling of hydrophilic plant fibers.
 The paper considers methods for obtaining microcrystalline cellulose and factors influencing the development of a fibrous suspension isolated from coniferous wood species in a grinding plant with inertial bodies. Multiphysical models of the flow of fibrous suspension in the installation are constructed. A study of the effect of grinding a fibrous suspension on the process of obtaining fine cellulose was carried out. The indicators of the finished product are given. The change in the degree of polymerization of cellulose that has previously passed the grinding stage, with different degrees of grinding according to the Shopper-Rigler, is analyzed. Data on cost reduction and resource savings (acid concentration, temperature and processing time) in the process of obtaining fine cellulose are presented.

Thermal stability of natural fiber reinforced biodegradable composites

Polymer composites reinforced with natural fibers are being increasingly developed by researcher and scientist in the recent field of material science due to their various applications in aerospace, marine and industries. The hydrophilic natural fibers are incompatible with the hydrophobic polymer matrices this leads to less interfacial bonding between fibers and matrix. In this paper, fibers were collected from desert plant prosopis juliflora and NaOH treatment was done to increase interfacial bonding of fiber-Matrix. Prosopis Juliflora fiber reinforced phenol formaldehyde composites were prepared with different fiber loading up to 20wt% and then characterized by thermo gravimetric analysis. This paper describes thermal properties composites materials by Thermo gravimetric analysis TGA and Differential scanning calorimetric DSC analysis of composite materials with different heating rates and hence establishes a connection between temperature and physical properties of substances. This study highlights the potential of alkali treatment in improving the thermal stability of the composites. This paper concludes that by, increasing the fiber weight percentage (fiber loading) in PF resin does increase the thermal stability of the resulting composite. The mass residue of untreated fiber reinforced PF composites with fiber loading 15% wt. UTFRPFC 15was 35%, while treated fiber reinforced PF composites with fiber loading 15% wt. ATFRPFC 15 had a mass residue of 75% at a temperature of 400°C. This clearly shows that alkali treatment significantly enhances the thermal stability of the composites. Alkali pre-treatment activates the fibers’ surface and helps increase the fiber’s mechanical strength.

Estimation of the hygro-elastic behavior of polymeric composites during moisture aging considering hygromechanical coupling

This study aims to combine, using a numerical tool, different phenomena of hygromechanical coupling in a unidirectional carbon/epoxy composite and to compare the results obtained with the cases where these couplings are considered separately. The first case of coupling considers the effect produced by the mechanical state on the diffusive behavior of the material. This was accomplished using the free volume theory, which links the trace of the matrix strain tensor to the moisture absorption capacity and the diffusion coefficient. The second case takes into account plasticization, that is, the effect of humidity on the mechanical properties of composites, without modifying the diffusion parameters. Finally, these two mechanisms are combined in a third configuration, which represents the original contribution of this present work. The results include the water content profiles, the diffusion coefficient, the transverse Young's modulus, the transverse hygroscopic expansion coefficient, as well as the induced local mechanical states. The interest of the work carried out is to pave the way for the extension to more complex materials, such as plant fiber biocomposites, in which the water absorption by the hydrophilic fibers should not be neglected anymore.

Comparative Study of Mechanical and Physical Properties of Rice Husk Filled Polyethylene Waste Composites

Polyethylene (PE), a type of plastic, is utilized extensively in many different applications and has become a significant part of our daily life. However, numerous plastic product manufactures have a significant environmental impact. As a result, several approaches have been investigated in order to reduce waste disposal issues. Rice husk (RH), on the other hand, is a form of agricultural waste that contains lignocellulosic fiber that can be used as a filler in polymer composites. As a result, combining both PE waste and RH fiber could be a viable option for saving our world. The objective of this study was to ascertain the impact of different RH fiber loadings, including 5, 10, 15, 20, and 25 %, on the mechanical and physical characteristics of composites manufactured from used HDPE and LDPE materials. Due to inadequate bonding between the hydrophilic fiber and the hydrophobic polymer matrix, it was discovered that increasing the filler loading lowered the tensile strength, elongation at break, and impact strength of the composites. In comparison to RH/HDPE, the tensile strength of RH/LDPE composites showed a greater decline at 45 % at the highest loading of 25 % RH fiber. Both composites showed a 98–99 % decrease in elongation at break as a result of constrained chain elongation and mobility. Additionally, the impact strength value of RH/HDPE waste composites decreased by 43 % compared to 31 % for RH/LDPE waste composites. In contrast, the inclusion of fillers improved the modulus and density of the composites substantially. While the trends for RH/HDPE and RH/LDPE composites are similar, RH/HDPE waste composites demonstrated superior mechanical characteristics than RH/LDPE waste composites.

Radiation assisted hydrophobization of jute fiber

AbstractHydrophobization of hydrophilic jute fiber, is of great importance as it can expand the applications of jute fiber in many fields. This work reports the hydrophobization of jute fiber by high‐energy radiation treatment which is an easy, single‐step, economical, and environment friendly method. Surface wettability of hydrophilic jute fiber is tuned by attaching long chain hydrocarbon molecules, namely butyl methacrylate, octyl acrylate and lauryl methacrylate, using gamma radiation. Lauryl methacrylate is found to be the most suitable agent among the molecules used for generating desired extent of hydrophobicity. Important reaction parameters, namely total dose, dose rate, monomer concentration, and solvent composition are optimized to achieve the desired degree of modification, for imparting hydrophobicity. Mechanical and thermal analysis reveals that there is no considerable damage to the base structure of fibers during modification. Scanning electron microscopy (SEM) is supporting evidence of the intactness of fiber after modification. The successful grafting of jute fiber has also been evidenced by SEM. This lauryl methacrylate modified jute can separate oily toxic liquids from aqueous media. The modified jute fiber may get enhanced applications in various fields.

Reclaimed lignosulfonate-modified bamboo fibers prepared via layer-by-layer self-assembly to reinforce poly(3-hydroxybutyrate) biocomposite

Fiber-reinforced poly(3-hydroxybutyrate) (PHB) biocomposites have been increasingly applied in various fields, such as building structures, interior decorations, and product packaging, due to their high strength to weight ratios, low thermal conductivities, low carbon footprints, and biodegradabilities. However, poor compatibility between the hydrophilic natural fibers and the thermoplastic biocomposites limits their mechanical strengths. This work proposes a method based on layer-by-layer self-assembly (LbL) to improve the interfacial compatibility between the PHB and bamboo fibers (BFs). Sodium lignosulfonate (SL) derived from pulp and paper industry waste was used as the raw material. Then, long carbon chains were introduced into the SL via the Mannich reaction. A hydrophobic self-assembled multilayer structure (SMS) was constructed on the surfaces of the BFs. The preparation process was environmentally friendly, controllable and simple. The mechanical properties were improved by the modifications, including the tensile strength (44%), flexural strength (13%), and impact strength (41%). The thermal properties of the fiber-reinforced biocomposites were also enhanced. This study presents a novel strategy for high-value utilization of industrial byproducts and the enhancement of biocomposite interfacial compatibility.

Flexible Hydrophilic Carbon Nanotube Fibers As Microelectrodes for Neuroscience

Implantable micro electrodes are generally employed to record and stimulate electrical activity of neurons in the nervous system. Most of the electrodes available today are made of metals and silicon that lack required flexibility resulting on a mechanical mismatch between soft tissues and rigid metals which induces faster biofouling and inconsistent performance for long-term applications. Biofouling triggered by inflammatory responses dramatically affect the performance of neural electrodes, resulting in decreased signal sensitivity and consistency over time. Thus, long-term clinical applications require electrically conducting flexible electrode materials with reduced dimensions and antibiofouling properties. These characteristics reduce the degree of inflammatory reactions and increase lifetime of neural electrodes. Carbon nanotubes (CNTs) are well known for their flexibility, electrical conductivity and chemical inertness. This talk will report the use of CNT fibers for neural stimulation and recording, and subsequent covalent functionalization of CNT fibers and films surfaces with hydrophilic, antibiofouling phosphorylcholine (PC) molecules. The electrochemical and spectroscopic characteristics, impedance properties, hydrophilicity, and in vitro antifouling nature of the functionalized CNT surfaces will be presented. The hydrophilicity of the functionalized CNT films was demonstrated by a decrease in the static contact angle from 134.4° ± 3.9° before to 15.7° ± 1.5° after one, and fully wetting after three functionalization cycles respectively. In addition, the extent of protein absorption on the functionalized CNT films were significantly lower than that on the non-functionalized CNT film. Surprisingly, the faradic charge-transfer properties and impedance of the CNT assemblies were preserved after functionalization with PC molecules. These functionalized CNT assemblies are promising for the development of low-impedance neural electrodes with higher hydrophilicity and protein-fouling resistance to inhibit inflammatory responses.

Functional Management of Waste Wood Flour as an Example of a 'Greener' Approach towards the Synthesis of Bio-Based Epoxy Resins.

Nowadays, in the era of growing ecological awareness, composites based on synthetic or bio-based polymers and fillers of natural origin find various potential applications. Plant-based materials are obtained using plant-derived materials, such as e.g., vegetable oil or wood fillers. Such synthesis of polymer composites allows for the selection of the reactants in terms of the potential requirements of the application. In the presented research polymer composites were obtained using bio-based high molecular-weight epoxy resins of hydroxylated soybean oil (SMEG) and a low-molecular-weight epoxy resin (EPR 0162) filled with the oak wood flour waste from the production of parquet flooring. To increase the poor compatibility between the highly hydrophilic wood fibers and the hydrophobic polymer matrix, waste wood flour (WF) was subjected to chemical modifications (mercerization, acetylation, and diisocyanate modification). Based on performed FT-IR and SEM analysis of wood flour, it was found that, among all performed modifications, the acetylation allows for the hydroxyl groups removal to the greatest extent. As a result of sequence synthesis including (1) the synthesis of SMEG_EPR polyaddition product, (2) the introduction of WF followed by its (3) curing with diisocyanate, obtained wood/polymer composites contain about 40% of raw materials of natural origin. As a consequence of the carried out modification of the wood waste flour, the compatibility of the filler and the bio-based polymer matrix was improved, resulting in an improvement in compressive strength by 3.51 MPa (SMEG_EPR_2% WF-10% NaOH) and 2.19 MPa (SMEG_EPR_2% A-WF) compared to samples containing unmodified wood flour. Additionally, concerning the results registered for pure SMEG_EPR composition, the introduction of 2 wt.% of wood filler resulted in a three/fourfold increase in the elongation at the break of the composition containing unmodified and chemically modified wood flour (10.99%-SMEG_EPR_2%WF; SMEG_EPR_2%WF-5%NaOH-10.36%; SMEG_EPR_2%WF-10%NaOH-9.54%, and 12.15%-SMEG_EPR_2%A-WF). Moreover, the incorporation of wood filler increased the value of the compression set of samples (2.40%-SMEG_EPR_2%WF, 2.39%-SMEG_EPR_2%WF-5%NaOH, and 2.34% for SMEG_EPR_2%WF-10%NaOH compared with 2.32%-SMEG_EPR).

High Surface Area Assemblies of Gold Nanoparticles on Hydrophilic Carbon Fiber Paper with Ionomer Overlayers for Aqueous CO2 Reduction Electrocatalysis to Clean Syngas

We report a universal approach for the utilization of nanoparticles on inexpensive, high surface area carbon substrates in aqueous applications. We immobilized gold nanoparticles from aqueous colloid on hydrophilic carbon fiber paper and assessed this electrode assembly in aqueous carbon dioxide reduction electrocatalysis. Uniform distributions of gold nanoparticles on carbon fibers and stable electrocatalytic current generation indicated that immobilization of gold nanoparticles on hydrophilic carbon fiber paper was successful. Surface analysis before and after electroreduction revealed that the detachment of citrate capping ligands enhanced the amount of exposed surface gold and concomitantly increased the CO-to-H2 ratio in subsequent CO2 reduction electrocatalysis. Systematic variations of ionomer overlayers controlled the ratio of produced CO and H2 towards useful syngas compositions and revealed mechanistic insights into catalyst microenvironments, to enhance CO selectivity. Our results demonstrate that hydrophilic carbon fiber paper is an excellent high surface area electrode substrate for the utilization of nanoparticulate electrocatalysts in aqueous electrolyte.

Special fog harvesting mode on bioinspired hydrophilic dual-thread spider silk fiber

Normal bioinspired spider silk fibers (BSSFs) show effective fog collection abilities but are weak in the rapid transport of captured droplets, which could potentially hinder the further improvement of fog harvesting efficiency. Factually, previous works have shown that the main axis of natural spider silk consists of two separate, parallel threads, similar to the microchannel structure of Sarracenia trichome. This structural feature may be an important factor contributing to the highly efficient fog harvesting ability of spider silks. However, to the best of our knowledge, previous studies on BSSFs have ignored this feature. In this work, inspired by spider silk and Sarracenia trichome, a novel bioinspired hydrophilic dual-thread spider silk fiber (HDSSF) is obtained via a simple dipping coating method to introduce capillary force. On the HDSSF, compared to previous works, a totally different fog harvesting mode was observed, i.e., captured droplets could be rapidly transported to spindle knots under the effect of capillary force and internal Laplace pressure difference via the connectivity of liquid film and no obvious droplets could be observed on the threads. The experimental observations and underlying mechanism analyses have verified that this special fog harvesting mode allows rapid transport and directional collection of droplets to accelerate the surface reconstruction rate, coupled with the high droplet capture ability of fiber, resulting in a significant improvement of fog harvesting efficiency (9.03 g cm−2·h−1, a 590% increase compared with normal BSSF). Such HDSSF is potentially applicable in high-efficiency fog harvesting systems, droplet transport devices and other engineering applications related to fog harvesting.

Easily scaled-up and portable 3D polysulfone hollow fiber membrane tree for high-efficient solar-driven clean water production

Solar-driven water evaporation based on photothermal conversion materials, such as woods, sponges, and membranes, have been proved to be promising in the field of fresh water generation. It's urgent to develop portable, versatile, and efficient photothermal materials for affordable freshwater supply. Here, a hydrophilic polysulfone hollow fiber membrane (PSF HFM) with gradient porous structure and diameter of 50 μm was prepared through one-step phase inversion method. Inspired by nature, a highly efficient 3D solar-driven steam evaporator was fabricated via chemical vapor deposition polymerization (CVDP) of hydrophobic polypyrrole (PPy) on PSF HFMs. With rational 3D structure, capillary-driven water transportation property, optical absorption as high as 95%, heat localization, photothermal conversion, a solar-driven water evaporation rate of 2.6 kg m−2·h−1, and the conversion efficiency of 173.2% could be achieved. Furthermore, the HFM tree with affluent light-harvesting, efficient thermal management, and excellent stability showed a purified water collection efficiency of 14.18 L/(m2·day) in practical application, providing a latent way to boost water purification, regeneration, and desalination.

Robust omniphobic ceramic hollow fibre membrane with leaf-like copper oxide hierarchical structure by membrane distillation

Omniphobic membranes have recently shown promising performance in water desalination using MD due to their ability to repel all liquid drop types and keep the membrane surface dry. This study successfully modified the surface of robust hydrophilic mullite-stainless steel hollow fibre membranes (M-SS HFMs) to omniphobic properties. The omniphobic layer was achieved through surface grafting with copper oxide (CuO) rough layer by a hydrothermal technique at different hydrothermal reaction times of 1, 2, 3, 4 and 5 h, followed by fluorination step using 1H,1H,2H,2H-perfluorode-cyltriethoxysilane (C8, 97 %). Next, the omniphobic membranes were characterized in terms of membrane morphology, roughness, mechanical strength, pore size/distribution, liquid entry pressure, contact angle and fouling accumulation. The prepared omniphobic M-SS HFMs were also tested through the DCMD system at 80 °C using a feed solution containing 35 g/L of NaCl and 10 mg/L of humic acid as a foulant agent. The results indicated that M-SS HFMs subjected to a 4 h hydrothermal reaction time, resulting in a leaf-like surface structure, exhibited superior characteristics compared to other omniphobic HFMs reported in the literature that used titania (SiO2), zinc oxide (ZnO), and cobalt (Co3O4) as roughing material. These superior features included higher roughness of 0.798 μm, liquid entry pressure of 5.40 bar, and enhanced liquid repellence and contact angles towards DI water of 167°, olive oil of 152°, and ethanol of 145°. Additionally, the M-SS HFMs at 4 h hydrothermal demonstrated remarkable performance in terms of rejection performance (99.99 %) and vapour flux stability of about 29 kg/m2.h in DCMD operations, surpassing the performance of omniphobic HFMs fabricated using mullite-ball clay, mullite-kaolinite, and alumina (Al2O3). Notably, no fouling/wetting on the membrane surface and elements leaching was observed throughout the MD operation. These findings highlight the potential of this omniphobic HFM for seawater desalination using DCMD systems, even in the presence of organic contaminants.

Improving the interface compatibility and mechanical performances of the cementitious composites by low-cost alkyl ketene dimer modified fibers

Natural fibers-reinforced cement composites have recently attracted more interest due to the trend in the development of sustainable construction materials. However, the poor fiber–matrix interface compatibility, which is caused by the swelling-shrinking behavior of hydrophilic natural fiber, negatively affects the mechanical properties of the composites thereby hindering their practical application. In order to promote interfacial compatibility, a new fiber surface treatment is needed. A low-cost alkyl ketene dimer (AKD) is adopted in this work, aiming at replacing the relatively expensive silane agents. This study focuses on fiber surface treatment and the resulting effects on the interface compatibility and mechanical performances of the composites. The effect of the fiber modification was characterized by FTIR and water absorption test; The interfacial compatibility of the composites was evaluated by the compatibility index calculation and SEM observation; A series of strength properties of the composites were carried out considering the influence of interface compatibility on mechanical performance. Results show a clear improvement in both interface compatibility and mechanical properties of the composites when AKD-modified fibers are used as reinforcement. The compressive and flexural strength are effectively increased up to 53 MPa and 8 MPa, respectively. Moreover, the approach of the low-cost AKD modification could further be applied to any natural fibers in cementitious composites, allowing cost-effectiveness in practical applications.