NaOH Solution Treatment Research Articles

Utilizing rice husk-derived Si/C composites to enhance energy capacity and cycle sustainability of lithium-ion batteries

Traditional graphite anodes have a specific capacity of approximately 372 mAh/g, whereas silicon presents a promising alternative with theoretical capacities reaching up to 4200 mAh/g. However, substantial volumetric changes in silicon during lithiation lead to rapid degradation of capacitance. This study explores the utilization of rice husk, an abundant agricultural waste, as a raw material for Si/C composites. Rice husk inherently contains significant amounts of silicon and carbon, rendering it a sustainable and economical source. The activated carbon was derived from rice husk by carbonization and thermochemically activation with activation temperature of 850 °C and KOH agent. The silicon dioxide was derived from rice husk by subjecting to annealing in a muffle furnace at 650 °C for 4 h following NaOH and HCl solution treatment. The silicon was derived from silicon dioxide by thermomagnesium treatment in a tube furnace at 700 °C for 120 min. SEM, elemental analysis, XRD, Raman, and FT-IR were used to characterize the materials to evaluate their morphological and structural composition. Electrochemical performance evaluation demonstrated improved energy capacity and stability, highlighting rice husk-derived Si/C composites as a viable solution for advancing lithium-ion battery performance. This innovative approach not only lowers production costs but also supports sustainable development by effectively utilizing agricultural waste.

Enhancing flame retardancy and antibacterial properties of wood veneer by promoting crosslinking in metal-organic framework structures

Decorative veneer, rotary cut from wood, serving as the outermost layer of decorative plates and is exposed to potential risks of fire hazards and bacterial growth. In this study, following the principle of eco-friendly and cost-effective, the polyamino polyether methylene phosphonate (PAPEMP) and magnesium chloride (MgCl2) were sequentially impregnated into the veneer, and then the alkaline environment was employed to facilitate the complexation, leading to the formation of cross-linked chains within the porous wood structure. Consequently, the modified wood veneer, endowed with exceptional flame retardancy, smoke suppression, antibacterial properties, and good wettability was successfully achieved. Through optimization in an alkaline environment, the modified decorative veneer exhibits a remarkable increase in limiting oxygen index from 19.7% in the pure veneer to 36.9%, coupled with a significant reduction of 19.38% in total heat release and 65.22% in total smoke release compared to the pure veneer. Additionally, the peak mass loss rate (PLMR) of the modified veneer was 66.41% lower than that of the pure veneer, and the char residue increased to 46.1%, representing a 149.19% improvement over the pure veneer. Compared with pure veneer, the wettability of modified veneer increased by 37.93%. Additionally, the tensile strength parallel to the grain of the modified veneer was enhanced by 22.09% compared to the veneer without NaOH solution treatment, and exhibits strong inhibitory effects on colony reproduction. The developed flame-retardant and antibacterial treatment processes for decorative veneers offer a novel and environmentally friendly method for utilizing precious tree veneers, suitable for a variety of precious woods, and successfully applied to decorative wooden doors and wooden fire-resistant doors.

Potential Use of Water Hyacinth (<i>Eichhornia crassipes</i>) as Growth Media: The Comparison of Acid and Base Treatment

This study aims to investigate the feasibility of using water hyacinth (WH) as growth media. It was carried out using different treatments, acid, and base, characterized by microscope optic, swelling index, soil water retention, and observing the growth of mung bean seeds for seven days. The results showed that the highest swelling index was NaOH solution treatment in WH with a 2.5 – 2 cm diameter at 560%. It was also shown that soil samples using WH with NaOH treatment can retain water, enhancing mung bean seeds’ rapid growth. Therefore, this preliminary study shows the potential use of WH as growth media.

Intensifying Electrochemical Activity of Ti3C2Tx MXene via Customized Interlayer Structure and Surface Chemistry.

MXene, a new intercalation pseudocapacitive electrode material, possesses a high theoretical capacitance for supercapacitor application. However, limited accessible interlayer space and active sites are major challenges to achieve this high capacitance in practical application. In order to stimulate the electrochemical activity of MXene to a greater extent, herein, a method of hydrothermal treatment in NaOH solution with reducing reagent-citric acid is first proposed. After this treatment, the gravimetric capacitance of MXene exhibits a significant enhancement, about 250% of the original value, reaching 543 F g-1 at 2 mV s-1. This improved electrochemical performance is attributed to the tailoring of an interlayer structure and surface chemistry state. An expanded and homogenized interlayer space is created, which provides enough space for electrolyte ions storage. The -F terminations are replaced with O-containing groups, which enhances the hydrophilicity, facilitating the electrolyte's accessibility to MXene's surface, and makes MXene show stronger adsorption for electrolyte ion-H+, providing sufficient electrochemical active sites. The change in terminations further leads to the increase in Ti valence, which becomes more prone to reduction. This work establishes full knowledge of the rational MXene design for electrochemical energy storage applications.

Study on Ultrasonic Far-Infrared Radiation Drying and Quality Characteristics of Wolfberry (Lycium barbarum L.) under Different Pretreatments

In order to explore the effects of different pretreatment methods on the ultrasonic far-infrared synergistic drying characteristics and quality of wolfberry, the bioactive components (polysaccharide, total phenol, total flavonoids, and antioxidants), the quality characteristics (rehydration ratio, color, vitamin C content, and betaine content), and the microstructure of the dried products were used as evaluation indices to test wolfberry treated by five different pretreatments (hot blanching; candied pretreatment; NaOH solution treatment; NaCl solution treatment; and Na2CO3 solution treatment). The results showed that hot blanching pretreatment improved the drying rate and shortened the drying time, and that the vitamin C content of dried products pretreated by hot blanching (92.56 mg/100 g) was higher than that of dried products pretreated by other methods. All five pretreatment methods increased the contents of the total phenols, vitamin C, and betaine of wolfberry. Wolfberry treated by candied pretreatment had lower color differences and higher contents of polysaccharide (0.83 g/g), total phenol (9.26 mg/g), and total flavonoids (2.61 mg/g) than wolfberry treated by the other pretreatment methods. Wolfberry pretreated by NaCl solution had the strongest antioxidant capacity (65.01%). Wolfberry pretreated by Na2CO3 solution had the highest betaine content (3.24%). The observation of the microstructure of the dried products revealed that hot blanching caused the most damage to wolfberry, while the candied pretreatment was less destructive to the tissue cells of wolfberry. On the whole, the dried wolfberry products obtained by the candied pretreatment were of a better quality than products obtained by the other pretreatment methods.

Trace amount of RuO2 loaded on TiO2 nanowires for efficient electrocatalytic degradation of ammonia nitrogen in wastewater

It is imperative to develop efficient and environmentally friendly technologies to remove ammonia nitrogen from the wastewater. Herein, RuO2 nanoparticles decorated TiO2 nanowires (RuO2/TiO2 NWs) were fabricated for efficient electrocatalytic degradation of ammonia nitrogen. TiO2 NWs were prepared on Ti mesh by hydrothermal treatment in NaOH solution, with diameter of 80–100 nm and length of ∼3 µm. Then RuO2 nanoparticles were decorated on TiO2 NWs by electrodeposition and annealing in air at 450 ℃. The effects of current, pH, initial ammonia concentration and chloride ion concentration on ammonia nitrogen degradation were investigated, and the possible degradation mechanism was discussed. After three hours of degradation in ammonia nitrogen waste liquid with NH4+-N concentration of 200 mg•L−1 and Cl- concentration of 2000 mg•L−1, the ammonia nitrogen removal rate of RuO2/TiO2 NWs reaches 99.876%. The mass loading of Ru is only 16.2 μg•cm−2, suggesting an extremely high ammonia nitrogen degradation efficiency. Electrochemical test shows that the conductivity of RuO2/TiO2 NWs is significantly enhanced as compared with that of TiO2 NWs. RuO2/TiO2 NWs also show good stability after 100 h of constant current test at 20 mA•cm−2 in ammonia nitrogen degradation. The prepared material can be used as an effective catalyst for the degradation of ammonia nitrogen in wastewater.

Uni-Directionally Oriented Fibro-Porous PLLA/Fibrin Bio-Hybrid Scaffold: Mechano-Morphological and Cell Studies.

In this study, we report a biohybrid oriented fibrous scaffold based on nanofibers of poly(l-lactic acid) (PLLA)/fibrin produced by electrospinning and subsequent post-treatment. Induced hydrolytic degradation of the fibers in 0.25 M NaOH solution for various time periods followed by the immobilization of fibrin on the hydrolyzed fiber surfaces was shown to significantly affect the mechanical properties, with the tensile strength (40.6 MPa ± 1.3) and strain at failure (38% ± 4.5) attaining a value within the range of human ligaments and ligament-replacement grafts. Unidirectional electrospinning with a mandrel rotational velocity of 26.4 m/s produced highly aligned fibers with an average diameter of 760 ± 96 nm. After a 20-min hydrolysis treatment in NaOH solution, this was further reduced to an average of 457 ± 89 nm, which is within the range of collagen bundles found in ligament tissue. Based on the results presented herein, the authors hypothesize that a combination of fiber orientation/alignment and immobilization of fibrin can result in the mechanical and morphological modification of PLLA tissue scaffolds for ligament-replacement grafts. Further, it was found that treatment with NaOH enhanced the osteogenic differentiation of hMSCs and the additional inclusion of fibrin further enhanced osteogenic differentiation, as demonstrated by decreased proliferative rates and increased ALP activity.

Role of SiOx in rice-husk-derived anodes for Li-ion batteries

The present study investigated the role of SiOx in a rice-husk-derived C/SiOx anode on the rate and cycling performance of a Li-ion battery. C/SiOx active materials with different SiOx contents (45, 24, and 5 mass%) were prepared from rice husk by heat treatment and immersion in NaOH solution. The C and SiOx specific capacities were 375 and 475 mAh g−1, respectively. A stable anodic operation was achieved by pre-lithiating the C/SiOx anode. Full-cells consisting of this anode and a Li(Ni0.5Co0.2Mn0.3)O2 cathode displayed high initial Coulombic efficiency (~ 85%) and high discharge specific capacity, indicating the maximum performance of the cathode (~ 150 mAh g−1). At increased current density, the higher the SiOx content, the higher the specific capacity retention, suggesting that the time response of the reversible reaction of SiOx with Li ions is faster than that of the C component. The full-cell with the highest SiOx content exhibited the largest decrease in cell specific capacity during the cycle test. The structural decay caused by the volume expansion of SiOx during Li-ion uptake and release degraded the cycling performance. Based on its high production yield and electrochemical benefits, degree of cycling performance degradation, and disadvantages of its removal, SiOx is preferably retained for Li-ion battery anode applications.

In situ crystallization of CHA / FAU zeolites on volcanic stone in the absence of organic agents

Japan has over 100 active volcanoes, which accounts for approximately 10% in the world. This paper discloses a novel way of utilizing volcanic stone. Microporous zeolites were crystallized on the macroporous volcanic stone by in situ crystallization method which is one-step soft hydrothermal treatment in NaOH solution with no additives. The volcanic stone has two roles in this method. One role is sources of SiO 2 , Al 2 O 3 , and alkali cations for crystallizing zeolites, and another role is a macroporous support of the zeolites. Each type of zeolite, CHA (0.38 nm pore) and FAU (0.74 nm pore), was mainly crystallized on the whole surface of the volcanic stone, which was controlled by adjusting concentration of NaOH solution. All the composite samples showed higher specific surface area than the raw volcanic stone. The highest value achieved in FAU zeolite sample was 439 m 2 /g which is as high as a commercial powdery zeolite. The adsorption abilities of the composite samples for ammonium ion measured by batch experiments were higher than the commercial powdery zeolite. • Zeolite-stone composites were prepared by in situ crystallization of volcanic stone. • Zeolites were precipitated without collapsing macroporous structure of the stone. • CHA-type zeolite was successfully crystallized in the absence of organic agents. • The highest surface area was 439 m 2 /g, as high as a commercial zeolite powder. • The samples showed higher adsorption abilities for NH 4 + than the commercial zeolite.

Silver - calcium titanate – titania decorated Ti6Al4V powders: An antimicrobial and biocompatible filler in composite scaffold for bone tissue engineering application

The present work describes a technique to develop silver nanoparticles decorated calcium titanate–titania (AgNPs-CT-TiO2) nanostructured layer over Ti6Al4V alloy powder by simple chemical and heat treatment approach. The NaOH solution and heat treatment form a uniform porous nano-network morphology of sodium titanate and subsequent calcium nitrate treatment transforms it into calcium titanate along with rutile TiO2. However, simultaneous treatment with calcium and silver nitrate solution allows the incorporation of both calcium and silver ions over the nano-network morphology leading to the formation of AgNPs decorated calcium titanate along with anatase TiO2 (AgNPs-CT-TiO2@Ti6Al4V) that collectively induces biocompatibility towards MG 63 osteoblast-like cells as well as antimicrobial activity against Staphylococcus aureus. Thus modified AgNPs-CT-TiO2@Ti6Al4V alloy powders were subsequently blended with polymethyl methacrylate to develop a composite scaffold using NaCl as a porogen. This composite could be used as a scaffold or bone cement in various bone tissue engineering applications.

Evaluation of the purification process of phosvitin extracted from chicken egg yolk using liquid chromatography

Phosvitin from chicken egg yolk, known as a phosphoglycoprotein, owns a very strong metal chelating property due to its polyanionic character. This study aimed to evaluate the factors affecting the purification process and suitable conditions to increase phosvitin’s purity. Phosvitin was separated from yolk granules by using 10% of NaCl solution in 0.05 M NaOH solution and heat treatment which removes lipoprotein from the extracted solution. The highest phosphorus content (58.14 mg) and phosphorus recovery rate (32.4%) were obtained at thermal treatment of 30℃ for 30 minutes. In addition, phosvitin was purified using anion-exchange chromatography (AEC) and gel-filtration chromatography (GFC). The fraction 1 (F1) obtained from AEC using UNO-Sphere Q at pH 8 had the recovery rate of phosvitin approximately 72.73%. Furthermore, fraction F1 was separated on GFC to obtain two main sub-fractions (F1 and F2). Sub-fraction F1 from gel filtration was composed mostly of β-phosvitin with a high recovery rate (81.93%) while F2 was dominant with α-phosvitin in a lower phosvitin recovery rate (16.89%). These findings will provide useful information for further researches on other properties of phosvitin so that it can be applied widely in human needs.

Effective and Simple NaOH-Modification Method to Remove Methyl Violet Dye via Ipomoea aquatica Roots

In this study, a simple chemical modification was applied to a sustainable and abundantly available resource, kangkong root (KR), to remove methyl violet 2B (MV) dye. The chemically modified adsorbent (NaOH-KR) was obtained using NaOH solution treatment. Batch adsorption experiments were carried out to investigate the effects of pH, ionic strength, contact time, adsorbent dosage, and initial dye concentration. A regeneration experiment was also carried out to assess the potential of reusability. The adsorption process was modelled using various kinetics and isotherm models, whereby the best-fitting models were evaluated by using the coefficient of determination ([Formula: see text]) and error functions. The Sips ([Formula: see text], χ 2 =0.16) and pseudo-second-order ([Formula: see text], [Formula: see text]) models were identified to best represent the adsorption process. The Sips model predicted a maximum adsorption capacity at 551.5 mg g-1 for NaOH-KR, which is 55% improvement in performance when compared to nonmodified KR. Lastly, the regeneration experiment showed that NaOH-KR was able to maintain reasonable dye removal even after five consecutive cycles of regenerating and reusing.

Improved Corrosion Resistance of Magnesium Alloy in Simulated Concrete Pore Solution by Hydrothermal Treatment.

Magnesium alloys are considered for building materials in this study due to their natural immunity to corrosion in alkaline concrete pore solution. But, chloride ions attack often hinders the application of most metals. Therefore, it is necessary to conduct a preliminary corrosion evaluation and attempt to find an effective way to resist the attack of chloride ions in concrete pore solution. In our study, hydrothermal treatment is carried out to modify Mg-9.3 wt. % Al alloy. After the treatment in NaOH solution for 10 h, scanning electron microscopy (SEM) reveals that a layer of dense coating with a thickness of about 5 μm is formed on Mg alloy. Energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD) are combined to analyze the coating, and it is thereby confirmed that the coating is mainly composed of Mg(OH)2. As expected, both immersion test and electrochemical corrosion test show that the coated magnesium alloy has a better corrosion resistance than the uncoated one in simulated concrete pore solution with and without chloride ions. In summary, it indicates that hydrothermal treatment is a feasible method to improve the corrosion resistance of Mg alloys used for building engineering from the perspective of corrosion science.

Effect of pre-treatment of flax tows on mechanical properties and microstructure of natural fiber reinforced geopolymer composites

In this work we studied the effect of pre-treatment of low-grade flax product (flax tows, FTs) by cleaning it mechanically from shives and weeds, followed by mercerization with a 5% aqueous NaOH solution and ultrasonic (US) treatment (22 kHz, 500 W) in alkaline medium, on the mechanical properties and microstructure of fly ash-based geopolymer (GP) composites. A series of three-point bending flexural tests was conducted on several types of GP/FTs composites while ATR-FTIR spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy were applied to evaluate morphological and chemical characteristics of FTs and their interface strength with GP matrix. It is shown that combined treatment with alkali and high-intensity ultrasound is an effective way to process and modify the surface of FTs fibers for reinforcing “green” geopolymer composites, providing the best technical and economic effects.

Efficient arsenic(III) removal from aqueous solution by a novel nanostructured iron-copper-manganese trimetal oxide

The removal of arsenite [As(III)] has attracted increasing attentions because it is higher toxic and more difficult to be removed from water than arsenate [As(V)]. For efficient As(III) uptake, a nanostructured iron-copper-manganese trimetal oxide (ICM) was therefore synthesized using a simultaneous oxidation and co-precipitation approach at room temperature. The as-prepared ICM exhibits multifunctional properties, which can not only oxidize effectively As(III) but also sorb the produced As(V). The maximal sorption capacity of As(III) reaches up to 131 mg/g under neutral conditions, which outperforms the majority of adsorbents reported in the literature. The As(III) sorption drops gradually as solution pH increases. However, it is not significantly influenced by ionic strength and present anions except for PO 4 3− , implying a relatively high selectivity. The active sorption sites of spent ICM can be easily restored through NaOH solution treatment. The removal of As(III) is a complicated process involving in both oxidation and adsorption, in which inner-sphere surface complexes are formed. The oxidation of As(III) to As(V) is mainly ascribed to the Mn oxide content in composite, whereas the adsorption of formed As(V) is predominately attributed to the Fe oxide and Cu oxide. The ICM might act as a promising alternative to remove arsenic from groundwater and wastewater, due to its good performance, low cost, facile synthesis and high reusability. • A novel nanostructured Fe-Cu-Mn trimetal oxide sorbent was fabricated. • The sorbent has a high sorption capacity for As(V) and As(III). • The sorbent is highly effective for As(III) removal at trace concentration. • As(III) uptake is mainly achieved by adsorption coupled with oxidation. • The spent sorbent can be easily regenerated and repeatedly used.

Improving Impact Strength and Water Absorption Properties of Enset Fiber Reinforced Polyester Composite

This study investigated the utilization of natural Enset fiber which is extracted from a perennial herbaceous plant cultivated in southwestern Ethiopia as reinforcement in Polyester resin matrix for non-load bearing structural elements. The composite samples have been developed by manual hand layup followed by a compression technique. The fiber was treated with a 5wt% NaOH solution (Alkali treatment) for better fiber-matrix adhesion. The fiber percentages (10wt%, 20wt% and 30 wt% by weight) were used for the preparation of the composite. Impact strength and water absorption properties of both raw and alkali-treated fiber-based composite were studied. The result obtained shows that NaOH solution treatment has a positive effect on the impact strength and water absorption properties of the composite. For raw fiber-based composite optimum impact strength was recorded at 20wt% fiber content. However, for treated fiber-based composite highest value was obtained at 30wt% fiber content. For both raw and treated fiber-based composite water absorption is directly proportional to fiber content and it is high for raw fiber-based composite

Fabrication of TiO2 nanofiber assembly from nanosheets (TiO2-NFs-NSs) by electrospinning-hydrothermal method for improved photoreactivity

Hierarchically structured nanomaterials have attracted much attention owing to their unique properties. In this study, TiO2 nanofibers assembled from nanosheets (TiO2-NFs-NSs) were fabricated through electrospinning technique, which was followed by hydrothermal treatment in NaOH solution. The effect of hydrothermal reaction time (0–3 h) on the structure and properties of TiO2 nanofibers (TiO2-NFs) was systematically studied, and TiO2-NFs was evaluated in terms of the photocatalytic activity toward photocatalytic oxidation of acetone and the photoelectric conversion efficiency of dye-sensitized solar cells. It was found that (1) hydrothermal treatment of TiO2-NFs in NaOH solution followed by acid washing and calcination results in the formation of TiO2-NFs-NSs; (2) upon extending the hydrothermal reaction time from 0 h to 3 h, the BET surface area of TiO2-NFs-NSs (T3.0 sample) increases 3.8 times (from 28 to 106 m2 g−1), while the pore volume increases 6.0 times (from 0.09 to 0.54 cm3 g−1); (3) when compared with those of pristine TiO2-NFs (T0 sample), the photoreactivity of the optimized TiO2-NFs-NSs toward acetone oxidation increases 3.1 times and the photoelectric conversion efficiency increases 2.3 times. The enhanced photoreactivity of TiO2-NFs-NSs is attributed to the enlarged BET surface area and increased pore volume, which facilitate the adsorption of substrate and penetration of gas, and the unique hollow structure of TiO2-NFs-NSs, which facilitates light harvesting through multiple optical reflections between the TiO2 nanosheets.

Water Absorption and Flexural Property of Unidirectional Polypropylene/Sumberejo Kenaf Fiber Composites

Kenaf fiber can be used as an alternative to synthetic fiber reinforcement in composites. This research was conducted in order to determine the flexural and diffusion properties of the composite by varying the fiber fractions. Before being used as a reinforcement, kenaf fiber was firstly treated with alkali treatment in NaOH solution for 24 hours. Polypropylene and kenaf fibers were fabricated with a hot press machine. The fiber fractions were 30 wt%, 40 wt%, 50 wt%, and pure polypropylene samples were also fabricated as a comparison. The highest flexural strength, the minimum water absorption and water content were found in the polypropylene/30 wt% kenaf fibre composites with the value of (4.77 ± 0.799) MPa, (3.61 ± 0.823)% and (0.192 ± 0.154)% respectively.

Facile Preparation of an Ether-Free Anion Exchange Membrane with Pendant Cyclic Quaternary Ammonium Groups

Ether-bond-free polyfluorene (PBF) anion exchange membranes (AEMs) containing flexible alkyl pendent chains terminated with piperidinium cations were prepared via one-pot, superacid-catalyzed polycondensation and a subsequent quaternization reaction. Hydrophilic and hydrophobic microphase segregation was observed in all AEMs. The hydroxide conductivity of PBF2-Br reaches up to 86 mS cm–1 at 80 °C, and 1H NMR showed no measurable degradation after alkaline treatment in aqueous NaOH (1 M) solution for 1200 h at 80 °C. Besides, a peak power density of 410 mW cm–2 was achieved at 60 °C for an alkaline fuel cell using the selected PBF1-OH (OH– form) as AEM.

MXene/Co3O4 composite material: Stable synthesis and its enhanced broadband microwave absorption

Abstract Microwave absorbers serve the purpose to ensure the transmission efficiency and accuracy in 5G telecommunications. Two-dimensional MXene has great potential in absorbing microwave. In this study, MXene(Ti3C2Tx)/Co3O4 composites are successfully fabricated by a facile and stable hydrothermal treatment in concentrated strong base and Argon environment, followed by a one-step annealing process. Phase composition, chemical state of elements, morphology and structure of the new composite materials are studied by systematical characterization. It is revealed that adsorbed Na+ ions and terminations, which are generated at the interface during hydrothermal treatment in concentrated NaOH solution, can protect the Ti3C2Tx from being decomposed. The synthesis mechanism is also proposed for stable fabrication of other MXene-based composite materials. The MXene/Co3O4 composite is able to perform single-band absorption, multiband absorption and even broadband absorption in 2–18 GHz band by tuning its composition and thickness. Particularly, better than 90% absorption in a wide range of 10.8–17 GHz can be achieved with a thickness of just 2 mm. Enhanced wideband absorption originates from the multilayer structure, the surface defects, the conductivity of Ti3C2Tx and the capacitance structure of Co3O4. Ultrathin and broadband high absorption features make the material a promising candidate for future application.