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Delamination is one of the most typical failure modes of fiber-reinforced polymer composite laminates. Thus, investigating and improving the delamination behavior of these laminates are of vital importance. The present research discovers and investigates the role of the alkaline treatment of twill-woven flax fabric on the delamination resistance of flax fiber-reinforced epoxy composite laminates. Initially, flax fibers were treated with different sodium hydroxide solution concentrations (2–5–10%) for 2 h. The influence of alkaline treatment on fiber characteristics was evaluated by performing a single-yarn tensile test, scanning electron microscopy, and Fourier transform infrared spectroscopy analysis for treated and untreated flax fibers. The appropriate treatment condition was selected based on the properties obtained from the tests conducted on the fiber level. Subsequently, to discover the role of alkaline treatment on delamination resistance, flax fabric was treated with the selected treatment condition for further composite fabrication. The treated and untreated flax fiber-reinforced epoxy composites were fabricated using a hand lay-up technique followed by hot compression. Interlaminar shear strength, double cantilever beam, and end-notch flexural tests were carried out for treated and untreated composites to determine the effect of alkaline treatment on the delamination resistance. The results proved that the alkaline treatment of flax fabric significantly improved the delamination resistance of treated composite laminates compared to untreated ones. The interlaminar shear strength, the mode I interlaminar fracture toughness (propagation), and mode II interlaminar fracture toughness were improved by 27.3%, 14%, and 24.9%, respectively, for treated composite laminates compared to untreated ones. [ABSTRACT FROM AUTHOR]

Purpose: This study examines how different stacking sequences of bamboo and flax fibers, treated with 5% aqueous sodium hydroxide (NaOH) and filled with 6wt% titanium oxide (TiO2), affect the physical, mechanical and dry sliding wear resistance properties of a hybrid composite. Design/methodology/approach: Composites with different fiber stacking arrangements were developed and tested per American Society for Testing and Materials (ASTM) standards to evaluate physical, mechanical and wear resistance properties, focusing on the impact of flax fiber mats at intermediate and outer layers. Findings: The hybrid composite significantly outperformed composites reinforced solely with bamboo fibers, showing a 65.95% increase in tensile strength, a 53.29% boost in flexural strength and a 91.01% improvement in impact strength. The configuration with multiple layers of flax fiber mat at intermediate and outer levels also demonstrated superior wear resistance. Originality/value: This study highlights the critical role of stacking order in optimizing the mechanical properties and wear resistance of hybrid composites. The findings provide valuable insights for the design and application of advanced composite materials, particularly in industries requiring high performance and durability. [ABSTRACT FROM AUTHOR]

Carrageenans are valuable marine polysaccharides derived from specific species of red seaweed (Rhodophyta) widely used as thickening and stabilizing agents across various industries. Kappaphycus alvarezii, predominantly cultivated in tropical countries, is the primary source of kappa-carrageenan. Traditional industrial extraction methods involve alkaline treatment for up to three hours followed by heating, which is inefficient and generates substantial waste. Thus, developing improved extraction techniques would be helpful for enhancing efficiency and reducing environmental impacts, solvent costs, energy consumption, and the required processing time. In this study, we explored innovative extraction methods, such as ultrasound-assisted extraction (UAE) and supercritical water extraction (SFE), together with other extraction methods to produce kappa-carrageenan from a new strain of K. alvarezii from the Philippines. FTIR-ATR spectroscopy was employed to characterize the structure of the different carrageenan fractions. We also examined the physicochemical properties of isolated phycocolloids, including viscosity, and the content of fatty acids, proteins, and carbohydrates. For refined carrageenan (RC), both the traditional extraction method and the UAE method used 1 M NaOH. Additionally, UAE (8% KOH) was employed to produce semi-refined carrageenan (SRC). UAE (8% KOH) produced a high yield of carrageenan, in half the extraction time (extraction yield: 76.70 ± 1.44), and improved carrageenan viscosity (658.7 cP), making this technique highly promising for industrial scaling up. On the other hand, SFE also yielded a significant amount of carrageenan, but the resulting product had the lowest viscosity and an acidic pH, posing safety concerns as classified by the EFSA's re-evaluation of carrageenan as a food additive. [ABSTRACT FROM AUTHOR]

The isolation of cellulose nanofibers from areca nut shell has been successfully carried out using a simple alkaline treatment, acid hydrolysis, and followed by a morphological modification using low‐energy sonication method. The alkaline treatment consists of dewaxing and bleaching process to remove lignin, while acid hydrolysis process was carried out to remove hemicellulose. Mechanical fibrillation was carried out via ultrasonication and low‐power homogenization with 100 W cleaner and 3 W homogenizer to obtain fine fibers. Following the scanning electron microscope (SEM) result, the ultrasonicated treatment sample showed better lignin and hemicellulose removal processes and increased dispersity, as well as reduce diameter of cellulose fibers from 710.4 to 451.6 nm. The particle size analyzer (PSA) showed that the colloidal cellulose after sonication provide a frequent diameter of 56 nm. Fourier transform infrared (FTIR) spectroscopy result showed that sonication is an effective removal process of noncellulosic components. X‐ray diffraction (XRD) analysis showed that the crystallinity of nanocellulose decrease following the sonication process. Hence, low‐energy ultrasonication is a viable approach to enhance the morphology and mechanical strength of cellulose nanofiber. [ABSTRACT FROM AUTHOR]

The development and characterization of bioactive surfaces based on chitosan-polyethylene glycol coatings modified with hydroxyapatite on Ti6Al4V alloy were conducted to enhance bioactivity. Characterization techniques such as scanning electron microscopy, X-ray diffraction, infrared spectroscopy, atomic absorption spectroscopy, and electrochemical impedance spectroscopy were used to evaluate coating properties, apatite formation after immersion in simulated body fluid, and electrochemical stability. Results demonstrated apatite deposition due to the bioactivity of the polymer-ceramic composite, with calcium accumulation observed on the substrate surface after 5 days of immersion. Electrochemical impedance spectroscopy revealed a highly capacitive layer in the 50:50 chitosanpolyethylene glycol coating with 0.05% w/v hydroxyapatite, indicating increased interaction with the biological medium while preserving the protective resistive properties of the Ti6Al4V alloy. These findings suggest that this coating composition is a promising material for bone tissue regeneration applications. [ABSTRACT FROM AUTHOR]

Red algae, abundant along the Moroccan coast, have fostered an agar-agar industry. However, industrial processing of red algae produces significant fibrous waste, posing environmental challenges. A new challenge is to find sustainable methods for repurposing this fibrous waste. Valorizing red-algae fibers in building materials promotes sustainable development and eco-construction. This study aims to valorize these red-algae residues as fiber reinforcements in compressed earth bricks (CEB). Various mass ratios of red-algae fibers (0.5%–3%) were incorporated into CEB. The addition of raw red-algae fibers to mixtures slightly increased the Atterberg limit values of the earth mixture. A slight adjustment in manufacturing water content was also observed with fiber addition. The incorporation of red-algae fibers did not improve the mechanical strengths of the CEB. Nevertheless, at a 1.5% addition ratio, CEB exhibited compressive and flexural strengths of 4.07 and 0.77 MPa respectively. To enhance mechanical properties, fibers were pre-saturated and subjected to alkaline and double coating treatments. Untreated and treated fibers were added to CEB at an optimal mass addition rate of 1.5%. Pre-saturated fibers showed a slight improvement of 5% in mechanical strength. However, alkali-treated and double-coated fibers offer a significant improvement of 20% in the mechanical strengths of CEB, demonstrating the efficacy of treatments. [ABSTRACT FROM AUTHOR]

The main drawback of recycled fibers is the deterioration of fiber bonding dependent papermaking properties (like tensile, tear and burst indexes) due to the hornification effect, as a results of drying during papermaking. In order to improve the papermaking properties through increasing fiber bonding, an alkaline treatment of Old Corrugated Cardboard (OCC) followed by fractionation were carried out in this investigation. Alkaline treatment dissolved 6.6 % organics (carbohydrates and lignin) and fibers became wider as a results of fiber swelling. The alkali treatment decreased fines from 39.9 % to 28.5 %, consequently, decreased drainage resistance from 26 °SR to 21 °SR. The papermaking properties of OCC pulp increased on alkaline treatment. Fiber fractionation of alkaline treated OCC further increased papermaking properties. At 40 °SR value, the tensile index, burst index and tear index of alkaline treated longer fiber fraction was 49 N m/g, 3.2 kPa m2/g, 7.2 mN m2/g, respectively while it was 40.4 N m/g, 2.1 kPa m2/g and 6.1 kPa m2/g, for non-treated longer fiber fraction, respectively. [ABSTRACT FROM AUTHOR]

In this research, a novel cellulosic fiber from the Cannonball tree was extracted and alkalized. The alkalisation was done for 45 min using a 5% NaOH solution. The cellulose percentage of the alkalized fiber was elevated to 69.23% from 54.96%. The increase in the crystallinity index (72.73% from 65.29%) of alkalized fiber was recognized via XRD analysis. Thermogravimetric analysis established that after alkalization maximal deterioration peak of (362.94 °C from 357.21 °C) and kinetic activation energy (67.5 kJ/mol from 60.33 kJ/mol) are enhanced. Lignin, wax, and impurity-free exterior layers are seen in the FE-SEM images of alkalized fiber. The absence of impurity elements in the EDX spectrum of alkalized CBFs indicated the abolishment of contaminants on the fibre's exterior. After the NaOH treatment, CBF tensile strength (71.5 ± 25 Mpa from 42.2 ± 10.5), and tensile modulus (4.15 ± 1.572 GPa from 2.1 ± 789) were increased. All the above findings concluded that CBFs are potential materials for reinforcement in fiber-reinforced plastics. [ABSTRACT FROM AUTHOR]

In this research work, efforts to develop a sustainable natural fiber-reinforced strain-hardening cementitious composite (NFSHCC) mixture are attempted. The key objective of the present study is to develop and characterize the NFSHCC mixture prepared using plant-based fibers such as pineapple, flax, kenaf, and hemp. First, the raw natural fibers were pretreated using an alkaline NaOH solution to remove the biodegradable properties such as wax, lignin, and so on. Using the treated natural fibers, an NFSHCC mixture was produced for a detailed mechanical and morphological characterization. Results reveal that flax fiber-based SHCC could develop the characteristics of artificial fiber-based SHCC, such as high tensile strength and large ultimate strain limits. Specifically, the flax SHCC specimens showed a large tensile strength and ultimate strain values of 10.3 MPa (1.49 ksi) and 2.5%, respectively. Moreover, the microstructural characterization using fieldemission scanning electron microscope analysis (FESEM) revealed excellent matrix-fiber bonding, which eventually led all NFSHCC samples to exhibit better mechanical properties on par with the commercial fibers. [ABSTRACT FROM AUTHOR]

The effect of acid treatment on TS-1 zeolite prior to alkaline treatment with TPAOH solution is investigated. 1H MAS NMR, UV–Vis, XPS, XRF, N2-sorption and TEM are applied to characterize the acid and/or alkaline treated TS-1 samples. It is found that acid treatment destructs the Si–O-Ti bonds of the framework, and promotes the conversion of 4-coordinated Ti into 6-coordinated Ti. Then in the subsequent alkaline treatment, part of framework Si–O-Si bonds are hydrolyzed and mesopores are formed. Meanwhile, the dissolved Si and Ti species could be incorporated back into the framework directed by TPAOH. Compared with TS-1-A, which is synthesized without acid treatment, TS-1-HA remains more active center and enhanced accessibility. Therefore, it shows high catalytic performance in cyclohexanone ammoximation reaction. [ABSTRACT FROM AUTHOR]

This study investigates the physical, mechanical, and structural characteristics of handmade paper samples derived from cellulose extracted from grass clippings using two distinct methods as follows: (1) alkali treatment and (2) alkali treatment followed by bleaching, coupled with the incorporation of barium sulfate as a mineral filler. Our investigation revealed that the handmade paper samples' densities, moisture contents, and thicknesses varied within the ranges of 0.436 to 0.549 g/cm3, 5.60 to 2.51%, and 0.41 to 0.50 mm, respectively. The tensile strength and folding endurance of the papers produced through alkali treatment with barium sulfate were notably superior to those produced from bleached pulp and barium sulfate. Our analysis indicates that several critical factors, including paper density, thickness, the crystallinity index, and the microfibrillar structure of cellulose, intricately influence the mechanical and strength properties of the samples. Using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques, we identified characteristic cellulose bonds and examined cellulose's crystalline and amorphous phases. Additionally, the crystallinity index of the samples was determined using both the Segal and peak deconvolution methods. Scanning electron microscopy (SEM) micrographs revealed interconnected networks of cellulose fibers with varying thicknesses and lengths, along with incorporated mineral filler within the cellulose fiber structure. Variations in mineral particle retention were attributed to the presence or absence of cellulose microfibrils. These findings contribute to our understanding of the observed strength characteristics of the paper samples and underscore the potential applications of cellulose derived from grass clippings, especially when combined with barium sulfate as a mineral filler in paper production. [ABSTRACT FROM AUTHOR]

Concentrating organic matter in sludge and converting it into methane through anaerobic bioconversion can improve resource recovery from domestic wastewater. Enhanced membrane coagulation (EMC) is highly efficient at concentrating organic matter, but residual coagulants (aluminum salts) can obstruct bioconversion by blocking microbial access. Limited research exists on evaluating EMC sludge bioconversion performance and addressing coagulant inhibition. This study proposes alkaline pre-fermentation to break down HO-Al-P backbones in coagulated sludge flocs, thereby improving hydrolysis and organic acid production for anaerobic digestion. Among the tested alkaline conditions (pH 9, pH 10, pH 11), pre-fermentation at pH 11 released the most organic matter (4710.0 mg/L SCOD), 20.4 times higher than without alkaline treatment. At pH 11, phosphate (61 mg/L PO43−–P) and organic acid production (2728.1 mg COD/L, with nearly 50% acetic acid) peaked, resulting in superior volatile solids removal (65.2%) and methane production (185.8 mL/g VS) during anaerobic digestion. Alkaline pre-fermentation favored alkali-tolerant bacteria such as Firmicutes and Actinobacteria, especially at pH 11, while neutrophilic Proteobacteria were suppressed. Trichococcus and Bifidobacterium, known acid producers, dominated under all conditions, with their abundance increasing at higher pH levels. Anaerobic digestion enriched fermentative bacteria like Chloroflexi and Synergistota (e.g., Thermovirga), especially in high pH reactors. Methanothrix, an acetoclastic methanogen, became the dominant methanogenic archaeon, indicating that methane production from EMC sludge primarily followed the acetoclastic methanogenesis pathway. Our findings demonstrate that alkaline pre-fermentation at pH 11 significantly enhances the hydrolysis efficiency of EMC sludge for methane recovery. [ABSTRACT FROM AUTHOR]

The flexural and impact response of completely biodegradable natural composites, specifically bamboo and pineapple leaf fiber (PALF) reinforced composites, is investigated using a combination of experimental and simulation techniques. The flexural strength and bending modulus are determined through 3-point bending tests while varying the weight fraction of the selected natural fibers from 5 to 15%. The impact of alkaline treatment at different percentages of 2 to 10% on the same properties such as flexural strength and bending modulus is also investigated. Subsequently, simulation techniques are employed to determine the behavior of the natural composite materials under bending loads. Finite element models are utilized to analyze the normal, and shear stresses in the composite structures. The research findings unveiled that incorporating a 10% weight fraction of bamboo fiber along with an 8% NaOH treatment led to the most significant enhancement in flexural strength, showcasing a notable advancement of 111.02%. Within the PALF fiber reinforced composite, employing 2% NaOH treated PALF fiber at a 15% weight fraction yielded an impressive improvement of 125.6%. [ABSTRACT FROM AUTHOR]

Investigations on the influence of carboxyl functionalized MWCNTs on epoxy composites solely reinforced by jute fiber are very scarce. Therefore, an attempt has been made to analyze the long-term moisture absorption behavior and thermal stability at the high-temperature range (30 °C-1200 °C) in jute FRC filled with varying amounts of functionalized MWCNTs (wt. %). Jute fibers derived from needle-punched jute mats were chemically pre-treated and were studied using Fourier Transform Infrared Spectroscopy (FT-IR). The MWCNTs were ultrasonicated to ensure uniform dispersion in the epoxy matrix. Scanning Electron Microscopy (SEM) was performed to observe the fiber, matrix, and filler interactions. As the composites were fabricated using the hand layup technique, air bubbles got entrapped into the specimens for which the void content was also reported. At a substantial saturation state (weight change

The development and characterization of bioactive surfaces based on chitosan-polyethylene glycol coatings modified with hydroxyapatite on Ti6Al4V alloy were conducted to enhance bioactivity. Characterization techniques such as scanning electron microscopy, X-ray diffraction, infrared spectroscopy, atomic absorption spectroscopy, and electrochemical impedance spectroscopy were used to evaluate coating properties, apatite formation after immersion in simulated body fluid, and electrochemical stability. Results demonstrated apatite deposition due to the bioactivity of the polymer-ceramic composite, with calcium accumulation observed on the substrate surface after 5 days of immersion. Electrochemical impedance spectroscopy revealed a highly capacitive layer in the 50:50 chitosan-polyethylene glycol coating with 0.05% w/v hydroxyapatite, indicating increased interaction with the biological medium while preserving the protective resistive properties of the Ti6Al4V alloy. These findings suggest that this coating composition is a promising material for bone tissue regeneration applications.

Abstract This study explores the utilization of eight readily available agricultural waste varieties in Nigeria—sugarcane bagasse, corn husk, corn cob, wheat husk, melina, acacia, mahogany, and ironwood sawdust—as potential sources of cellulose. Gravimetric analysis was employed to assess the cellulose content of these wastes, following which two selected wastes were combined based on their cellulose content and abundance to serve as the raw material for the extraction process. Response Surface Methodology, including Box-Behnken design, was applied to enhance control over variables, establish an optimal starting point, and determine the most favorable reaction conditions. The cellulose extracted under various conditions was comprehensively examined for content, structure, extent of crystallinity, and morphological properties. Characterization techniques such as X-ray Diffraction, Scanning Electron Microscopy, and Fourier Transform Infrared Spectroscopy were employed for detailed analysis. Compositional analysis revealed sugarcane bagasse and corn cob to possess the highest cellulose content, at 41 ± 0.41% and 40 ± 0.32% respectively, with FTIR analysis confirming relatively low C=C bond intensity in these samples. RSM optimization indicated a potential 46% isolated yield from a hybrid composition of sugarcane bagasse and corn cob at NaOH concentration of 2%, temperature of 45 °C, and 10 ml of 38% H2O2. However, FTIR analyses revealed the persistence of non-cellulosic materials in this sample. Further analysis demonstrated that cellulose isolated at NaOH concentration of 10%, temperature of 70 °C, and 20 ml of 38% H2O2 was of high purity, with a yield of 42%. Numerical optimization within this extraction condition range predicted a yield of 45.6% at NaOH concentration of 5%, temperature of 45 °C, and 20 ml of 38% H2O2. Model validation confirmed an actual yield of 43.9% at this condition, aligning closely with the predicted value. These findings underscore the significant potential of combinning and utilizing agricultural wastes as a valuable source of cellulose, paving the way for sustainable and resource-efficient practices in various industrial applications.

In this research, we were interested in studying whether vetiver fibers (VFs) treated with different concentrations of sodium hydroxide (NaOH) affect the mechanical properties of VF and epoxy resin (ER) composite material in a better way. As part of the experiment, VFs were treated with NaOH in various concentrations ranging from 0.5, 1, 1.5, 2, 2.5, and 3 mol/L. All of them were molded into composite material in the ratio of 10 wt% with ER. After that, they were tested for mechanical properties such as the tensile strength, impact strength, bending strength, and compressive strength to find the best mechanical properties. In addition, the surface was investigated with scanning electron microscopy (SEM) for adhesion of the VFs with ER. The results of the experiment were not as expected. We found that, increasing the concentration of vetiver treated with sodium hydroxide resulted in a decrease in the mechanical properties of the composite. The best values for impact, tensile, bending, and compressive strengths were 256.42 kJ/m2, 38.45 MPa, 43.70 MPa, and 110.27 MPa, respectively, and 0.5 mol/L is the best concentration of NaOH for mechanical strengths of the composites. Moreover, from SEM technique, it was found that the mechanical properties decreased at higher concentrations. This may be caused by damage to the VFs due to excessive NaOH corrosion and this point should be taken for further study.

This study focused on manufacturing efficient automobile sound-absorbing materials through alkaline treatment and dimple processing of recycled polyethylene terephthalate (rPET) nonwoven fabric. The rPET nonwoven fabric was produced with a sound-absorbing material through compression molding. It was improved through the development of porous sound-absorbing materials through alkaline treatment and resonant sound-absorbing materials through dimple processing. As a result of morphological analysis, alkaline treatment showed that pore size and air permeability increased according to temperature and concentration increase conditions. On the other hand, dimple processing caused a decrease in air permeability and a decrease in pores due to yarn fusion, and as the dimple diameter increased, the sound-absorbing coefficient increased in the 5000 Hz band. Finally, it was judged that effective sound absorption performance would be improved through a simple process through alkaline treatment and dimple processing, and thus there would be applicability in various industrial fields.

This study focused on manufacturing efficient automobile sound-absorbing materials through alkaline treatment and dimple processing of recycled polyethylene terephthalate (rPET) nonwoven fabric. The rPET nonwoven fabric was produced with a sound-absorbing material through compression molding. It was improved through the development of porous sound-absorbing materials through alkaline treatment and resonant sound-absorbing materials through dimple processing. As a result of morphological analysis, alkaline treatment showed that pore size and air permeability increased according to temperature and concentration increase conditions. On the other hand, dimple processing caused a decrease in air permeability and a decrease in pores due to yarn fusion, and as the dimple diameter increased, the sound-absorbing coefficient increased in the 5000 Hz band. Finally, it was judged that effective sound absorption performance would be improved through a simple process through alkaline treatment and dimple processing, and thus there would be applicability in various industrial fields. [ABSTRACT FROM AUTHOR]

This study aims to develop sustainable composite materials using recycled polypropylene and abaca natural fibres following the compression molding technique. The chopped abaca fibres have been treated with different alkaline (NaOH) concentrations (4, 8 & 12 wt %) to eliminate the lignin, hemicellulose, wax and pectin components and then subjected to FTIR analysis to verify the presence of their functional elements in the structure. Likewise, XRD analysis is performed to verify the crystalline phase transition in recycled polypropylene and abaca fibres. The SEM study reveals that the treated abaca fibres have a rougher surface than the untreated ones. TGA analysis confirms the good thermal stability of recycled polypropylene and abaca fibres. The mechanical parameters of the developed composite, including its tensile strength, flexural strength, and impact strength, are studied. It is found that the composites with greater abaca fibres loading and 12% NaOH treatment exhibit good mechanical strength. Also, the composite with 30% abaca fibre loading has the lowest water absorption levels as compared to other composites. This study also analyzes the failure mode of composites during mechanical testing. The developed composite can be used in interior car components. [ABSTRACT FROM AUTHOR]

Rice husk being the major agro-waste could serve as the renewable source of silica. This silica could be a replacement for industrial and pharmaceutical applications. Industrial grade silica require purity ranging from 80 to 100% necessitating the elimination of organic and metallic impurities from biomass. This study compares the ability of pre-treatment process in improving the purity of silica. Silica with difference in purity is extracted by employing simple (conventional alkaline treatment—CAT) and rigorous (soaking/acid/alkaline—SAA) pretreatment on husk. The alkali earth metal removal percentage are 41.71%, 81.69%, and 40.37% for Na, K, and Mg respectively by adopting SAA method. In addition, the significance of impurity elimination is reflected in the textural properties where the SAA silica exhibited an 80% increase in BET surface area compared to CAT silica. SAA silica was purely amorphous whereas CAT silica showed crystalline phase in XRD analysis. Ultrasonication effect on size reduction was more pronounced. The binding nature of elements from XPS analysis indicated the presence of silica as silicon oxide and silicon dioxide. The elemental composition of SAA silica revealed drastic decrease in the contents of Fe2O3, K2O, and Al2O3 compared to CAT silica. The difference in silica arises from the soaking process imparting hydrophilic nature to the husk increasing the hydroxyl group on its surface. The interaction between the hydroxyl group and the acid during pre-treatment aided in impurity elimination. This suggests the SAA pretreatment as suitable process for efficient extraction of silica through impurity elimination. [ABSTRACT FROM AUTHOR]

Cellulose is one of the most abundant biopolymers on Earth and is of most significant interest due to its properties and uses. Cellulose can be obtained from agro-industrial residues, such as rice husk, whose cellulose content is approximately 30%. In this study, cellulose microfibers were extracted from rice husks. Fibers were obtained by submitting the biomass to alkali (NaOH) and bleaching treatments. These treatments have already been reported in the literature; however, variables such as the concentration of reagents, the time, and the temperature of the chemical treatment have yet to be optimized. A factorial design of experiments with 3 factors and 2 levels for each factor was proposed to optimize the chemical processes. It was determined through the analysis of variance (ANOVA) that the factors evaluated significantly influenced the elimination of non-cellulosic compounds, and that the chemical treatment was more efficient when the factors took high level values. Ultraviolet-visible spectroscopy (UV-Vis) analysis showed the successful removal of undesired components during the alkaline treatment. The effect of the treatments on the morphology upon removing hemicelluloses, lignin, and inorganic material was evaluated through Scanning Electron Microscopy (SEM). The increase in the thermal stability in the alkali-treated rice husk and in cellulose microfibers, compared to the raw rice husk, was established by thermogravimetric analysis (TGA). X-ray diffraction (XRD) indicated that the treatments increased the percentage of crystallinity. [ABSTRACT FROM AUTHOR]

Composite materials increasingly use biofibres because of their lightweight, remarkable strength, stiffness, and biodegradability. Nanofillers are becoming more common in bio-nanocomposite (BNC) applications in industries like aeronautics and marine engineering. Research is underway to determine the effects of nanofiller alumina (Al2O3) and magnesia (MgO) on BNC tensile, bending, and impact properties when coupled with reinforcing surface-treated jute fibres. Vacuum-bagged composite laminates were made by adding Al2O3 and MgO nanofiller (50 nm in diameter) to the epoxy range from 1 to 4% by weight. One set of fibres was treated with a 5% NaOH solution to see the effect of surface treatment and nanofillers on the mechanical properties of the composite. Surface-treated jute-reinforced composite outperformed untreated in tensile, bending, and impact properties. While on the additive inclusion of 3% of nanofiller, the highest properties were achieved, the treated jute-reinforced MgO-filled laminates increased the tensile strength by 60%, flexural strength by 67%, and impact strength by 42% as compared to laminates without nanofillers. SEM images show an array of imperfections, including interfacial performance, fibre breakage, fibre withdrawal, agglomeration, cracks, and voids. Surface treatment and nanofillers were shown to enhance the BNC's mechanical properties. [ABSTRACT FROM AUTHOR]

Porous bioceramics are commonly used as support structures for bone growth and repair. However, their mechanical properties have been limited by high macroporosity and microporosity. Alumina ceramics (Al2O3) are preferred for bone implants due to their mechanical reliability, chemical stability, and biological compatibility. However, the bioinert nature of aluminum oxide makes it challenging for bone ingrowth and implant anchorage. To address this, ceramic scaffold samples with concentrated porosity have been developed. This study aimed to create porous Al2O3 and explore surface modifications using UV exposure, amino acid treatment (L-lysine), and alkaline treatment (NaOH) for applications in orthopedics and dentistry. The porous alumina samples underwent sintering at 1400°C and drying at 100°C. They were then analyzed for mechanical, morphological, and structural characteristics through various tests and microscopy techniques. The results revealed increased surface roughness after 16 hours of alkaline treatment and one hour of UV treatment, and decreased roughness with amino acid treatment for samples pre-treated with NaOH for 16 hours. Our results showed an increase in porosity with Alkaline and UV treatment and decrease with amino acid treatment, also results shows decrease in mechanical properties for alkali and UV treatments (Hardness and Compressive Strength) as it is in the range of cancellous bone strength. According to the current work, the contact angle between the untreated and treated samples with UV, amino acid, and NaOH was zero, which indicates that these surfaces are hyper hydrophilic. High porosity and surface roughness may be the cause of this behavior. Biological test evaluated by XRD and FESEM exhibited formation of Hydroxyapatite film when immersed in SBF for 7 days. [ABSTRACT FROM AUTHOR]

In this experimental study, it was aimed to research the possibilities of improving the dyeing properties of 100% polyester fabrics. For this purpose, the polyester fabrics were pretreated with sodium hydroxide and chitosan. The hydrophility tests, SEM-EDX, and FTIR-ATR analyses of the pretreated fabrics were done, and they were then dyed with acid dye at 90 °C. After dyeing processes, the CIEL*a*b* color values, color strength, fastness properties (to washing, water, perspiration, and rubbing) of dyed samples were investigated, and the bursting strength of the undyed and dyed samples was also tested. The results showed that it is possible to improve the dyeing properties of 100% polyester fabrics via chitosan application and that the polyester fabrics can be dyed with acid dyes at low temperatures after being cationized with chitosan following the sodium hydroxide application. [ABSTRACT FROM AUTHOR]

Magnesium alloys have been extensively studied as degradable biomaterials for clinical applications due to their biocompatibility and mechanical properties. However, their poor corrosion resistance can lead to issues such as osteolysis and the release of gaseous hydrogen. This study investigated the influence of the activation time of magnesium surfaces in a sodium hydroxide (NaOH) solution on the concentration of active hydroxyl groups and corrosion resistance. The results indicated that immersion time significantly influences the formation of a corrosion-resistant film and the distribution of surface hydroxyl groups. Specifically, specimens treated for 7.5 h exhibited the highest concentration of hydroxyl groups and the most uniform oxide film distribution. Electrochemical tests demonstrated capacitive behavior and passive surface formation for all evaluated times, with the 7.5-h immersion in NaOH yielding superior corrosion resistance, lower current density, and a more efficient and thicker protective film. SEM and EDS analyses confirmed increased formation of Mg(OH)₂ for samples treated for 5 and 7.5 h, while a 10-h treatment resulted in a brittle, porous layer prone to degradation. Statistical analysis using ANOVA and Fisher's LSD test corroborated these findings. The optimal 7.5-h alkali treatment enhanced magnesium's corrosion resistance and surface properties, making it a promising candidate for orthopedic implants. However, further studies are necessary to assess biocompatibility and physiological responses before clinical implementation.

There is a high demand for bio composites due to its eco-friendliness, lightweight, availability, low cost and life-cycle superior. This bio composite was prepared by reinforcing the cementitious matrix with alkali treated abaca fiber. However, one of the major concerns about this material is its durability in the cementitious matrix. This study gives an insight into the comparison of alkali treated fiber reinforced mortar (MFTHS) vs reference mortar with no fiber (MSF) through flexural, compressive, shrinkage and tensile test at 28 days, it also compared two processes of wet/dry cycles subjecting samples to the same mechanical properties. MFTHS increased its mechanical properties for an average of 25% compared to MSF. The same pattern occurs after applying WD-1 and WD-2, MFTHS showed better bonding between the matrix and the treated abaca fiber.

A surface response design was employed to develop a sodium hydroxide (NaOH) pretreatment method for Quercus variabilis Blume using low NaOH concentration at low temperature. Nevertheless, the persistent issues associated with alkaline pretreatment of lignocellulose, namely high-water consumption and wastewater generation, remain prevalent in this pretreatment process. To address these challenges, this study aimed to conduct enzymatic hydrolysis of NaOH-treated Q. variabilis Blume without the intermediary washing steps. The results revealed that, following pretreatment and solid-liquid separation, NaOH-treated Q. variabilis Blume could be directly subjected to cellulase-mediated hydrolysis with pH adjustment, eliminating the need for washing steps. The maximum enzymatic hydrolysis efficiency reached 95.9% under specific conditions (1.2% NaOH, 8.9 °C, 32.1 h). This approach offers a promising avenue to enhance the enzyme hydrolysis rate of NaOH-treated lignocellulose. Notably, the low-temperature and low-concentration NaOH treatment effectively removed a substantial portion of lignin and hemicelluloses, resulting in a higher crystallinity index of the cellulose-rich residue compared to substrates treated solely with steam explosion. The integration of direct pretreatment and alkaline treatment emerges as an environmentally friendly and economically viable method for producing glucose and high-purity lignin. The obtained lignin can be further transformed into high-value products within the biorefinery framework.

Carrageenans are valuable marine polysaccharides derived from specific species of red seaweed (Rhodophyta) widely used as thickening and stabilizing agents across various industries. Kappaphycus alvarezii, predominantly cultivated in tropical countries, is the primary source of kappa-carrageenan. Traditional industrial extraction methods involve alkaline treatment for up to three hours followed by heating, which is inefficient and generates substantial waste. Thus, developing improved extraction techniques would be helpful for enhancing efficiency and reducing environmental impacts, solvent costs, energy consumption, and the required processing time. In this study, we explored innovative extraction methods, such as ultrasound-assisted extraction (UAE) and supercritical water extraction (SFE), together with other extraction methods to produce kappa-carrageenan from a new strain of K. alvarezii from the Philippines. FTIR-ATR spectroscopy was employed to characterize the structure of the different carrageenan fractions. We also examined the physicochemical properties of isolated phycocolloids, including viscosity, and the content of fatty acids, proteins, and carbohydrates. For refined carrageenan (RC), both the traditional extraction method and the UAE method used 1 M NaOH. Additionally, UAE (8% KOH) was employed to produce semi-refined carrageenan (SRC). UAE (8% KOH) produced a high yield of carrageenan, in half the extraction time (extraction yield: 76.70 ± 1.44), and improved carrageenan viscosity (658.7 cP), making this technique highly promising for industrial scaling up. On the other hand, SFE also yielded a significant amount of carrageenan, but the resulting product had the lowest viscosity and an acidic pH, posing safety concerns as classified by the EFSA’s re-evaluation of carrageenan as a food additive.

• Directions for future research of sustainable use of biosolids as a N source. • Global biosolids regulations and common biosolids treatment methods are discussed. • Higher total N content in HDB and reduced N availability from CB are reported. • Key factors in biosolids treatment affecting biosolids properties are identified. • Existing models of soil N dynamics after biosolids application are summarized. Application of biosolids to agricultural land has gained increasing attention due to their rich nutrient content. There are a variety of treatment processes for converting sewage sludge to biosolids. Different treatment processes can change the physicochemical properties of the raw sewage sludge and affect the dynamics of nutrient release in biosolids-amended soils. This paper reviews heat drying, alkaline treatment, and composting as biosolids treatment processes and discusses the effects of these treatments on biosolid nitrogen (N) content and availability. Most N in the biosolids remain in organic forms, regardless of biosolids treatment type but considerable variation exists in the mean values of total N and mineralizable N across different types of biosolids. The highest mean total N content was recorded in heat-dried biosolids (HDB) (4.92%), followed by composted biosolids (CB) (2.25%) and alkaline-treated biosolids (ATB) (2.14%). The mean mineralizable N value was similar between HDB and ATB, with a broader range of mineralizable N in ATB. The lowest N availability was observed in CB. Although many models have been extensively studied for predicting potential N mineralization in soils amended with organic amendments, limited research has attempted to model soil N mineralization following biosolids application. With biosolids being a popular, economical, and eco-friendly alternative to chemical N-fertilizers, understanding biosolids treatment effects on biosolids properties is important for developing a sound biosolids management system. Moreover, modeling N mineralization in biosolids-amended soils is essential for the adoption of sustainable farming practices that maximize the agronomic value of all types of biosolids. [ABSTRACT FROM AUTHOR]

Using alkali pretreatment can effectively remove residual variable-valence metals from non-metallic powder (WPCBP) in waste printed circuit boards. However, substantial amounts of waste lye are generated, which causes secondary pollution. On this basis, this study innovatively utilized waste alkali lye to prepare nano-magnesium hydroxide. When the dispersant polyethylene glycol 6000 was used at a dosage of 3 wt.% of the theoretical yield of magnesium hydroxide, the synthesized nano-magnesium hydroxide exhibited well-defined crystallinity, good thermal stability and uniform particle size distribution, with a median diameter of 197 nm. Furthermore, the in situ method was selected to prepare WPCBP/Mg(OH)2 hybrid filler (MW) and the combustion behavior, thermal and mechanical properties of PP blends filled with MW were evaluated. The combustion behavior of the PP/MW blends increased with the increasing hybrid ratio of Mg(OH)2, and the MW hybrid filler reinforced PP blends showed better thermal and mechanical properties compared to the PP/WPCBP blends. Furthermore, the dynamic mechanical properties of the PP/MW blends were also increased due to the improved interfacial adhesion between the MW fillers and PP matrix. This method demonstrated high economic and environmental value, providing a new direction for the high value-added utilization of WPCBP. [ABSTRACT FROM AUTHOR]

Fermented fish bone residue (FFBR) is an underused by-product of the industrial-scale production of fermented fish sauce. Subjecting FFBR to proper alkaline treatment can transform FFBR into biocalcium, which can be added to fish emulsion sausage (FES) to increase its calcium content. This study comprised two experiments. First, we aimed to find the most suitable alkaline treatment conditions for preparing biocalcium from FFBR. Alkaline treatments combining three sodium hydroxide (NaOH) concentrations (0%, 3%, and 6%) and three soaking times (0, 1, and 2 h) were tested. Quality parameters of alkaline-treated biocalcium (crude protein, crude fat, ash content, calcium, phosphorus, crude fiber, salt content, CIE color values, morphology of biocalcium particles, and the intensity of the fermented fish smell) were assessed. Second, we fortified FES with the properly treated biocalcium (0, 12, 24, or 36 g) and evaluated the sausage's calcium, phosphorus, crude fiber, salt content, pH, CIE color values, texture profile analysis (TPA), emulsion stability, and sensory criteria. It was found that treatment with 3% or 6% NaOH produced better crude protein, ash content, calcium, and CIE color value results than no alkaline treatment. These two NaOH concentrations effectively lowered the salt content and the intensity of the fermented fish smell. However, 3% and 6% NaOH produced similar results. A soaking time of 1 h or 2 h produced better results than no soaking in terms of crude protein, crude fat, ash content, calcium, phosphorus, CIE color values, and the intensity of fermented fish smell. However, 1 h and 2 h produced similar results. It is concluded that 3% NaOH and soaking for 1 h would be the most suitable alkaline treatment to prepare biocalcium from FFBR. Fortifying FES with biocalcium from FFBR increased the calcium and phosphorus contents but slightly reduced TPA. The other FES quality parameters were unaffected by biocalcium fortification. [ABSTRACT FROM AUTHOR]

Natural fibers are environmentally friendly materials incorporated into polymer matrices as reinforcement agents. Several fibers are available in nature, such as cotton, jute, sisal, bamboo, hemp, banana, coir, and flax. However, in some cases, poor compatibility between fiber/polymer is observed, limiting their utilization. To overcome this disadvantage, chemical treatments can be applied to the fibers to alter their chemical composition, surface morphology, and mechanical properties. In comparison with other methods, mercerization is a popular methodology largely used to modify the properties of fibers once is inexpensive and does not require toxic chemicals. The main modifications caused by mercerization regarding chemical composition are the removal of wax, oils, and impurities of the surface of the fibers, besides a decrease in lignin and hemicellulose contents, and an increase in cellulose content. Fiber surface morphology becomes cleaner, and mechanical parameters, such as tensile strength and rigidity, are generally improved. Although these are some common modifications, mercerization process parameters must be well-adjusted to obtain optimized results. Unlike other published articles, this review covers the mercerization parameters adopted for several types of natural fibers to establish a correlation between the main effects of the process on the physical–chemical, morphological, and mechanical properties of the fibers. [ABSTRACT FROM AUTHOR]

Natural fibre–polymer composites are widely used because they are economical and ecologically beneficial in a variety of applications. In order to improve its performance, this study focuses on examining the mechanical characteristics of an epoxy composite material that has been reinforced with banana fibre mats that have undergone NaOH treatment. Additionally, using various configurations both with and without eggshell powder (ESP), the compression moulding method was used to fabricate and investigate the impact of ESP on these mechanical qualities. The results showed that the composite with 25 weight percent banana fibre and 2.5 weight percent ESP had the maximum tensile strength (31.21 MPa), bending strength (33.69 MPa), and impact strength (2.84 kJ/m2). Strong interfacial adhesion between the banana and eggshell components was discovered via the microscopic examination of shattered surfaces. Notably, compared to untreated banana composites, the alkaline-treated banana materials showed fewer occurrences of pull-outs and fractures, leading to noticeably better mechanical performance. [ABSTRACT FROM AUTHOR]