NaOH Treatment Research Articles

Impact of different NaOH treatments on biocellulose properties from coconut water fermented by Lentilactobacillus parafarraginis

Background: Biocellulose is a natural polymer produced by bacteria with distinct physicochemical properties, although it has a chemical composition identical to plant cellulose. Before use, biocellulose was purified by chemical treatment to increase its properties. Objective: The study aimed to evaluate biocellulose properties using NaOH solution as a purification agent. Method: After harvesting, all samples were purified using NaOH of 0.25 M (BC0.25), 0.5 M (BC0.5), and 1 M (BC1) and determined for their properties, such as mechanical strength, swelling degree, water vapour transmission, and moisture content. Analysis of scanning electron microscope (SEM) images and Fourier Transform Infrared Spectroscopy (FTIR) spectra were also performed for characterisation. Result: BC0.5 exhibited the highest tensile strength of 15.38±0.45 MPa and elongation at a break of 38.40±0.58%. BC1 had the highest swelling degree of 131.24±0.70%, water vapour transmission of 400.00±0.36 g/m2, and moisture content of 6.44±0.14%. Nevertheless, there were slight alterations in morphological structure and spectral peaks because of the high concentration of NaOH. Conclusion: The use of NaOH treatment of 0.5 M in biocellulose purification removed more contaminants and resulted in better properties than other concentrations.

Changes in crystallinity of sago palm (Metroxylon sago spp.) waste during cellulose extraction

Changes in crystallinity of sago palm (Metroxylon sago spp.) waste during cellulose extraction

Influence of sodium hydroxide, silane, and siloxane treatments on the moisture sensitivity and mechanical properties of flax fiber composites

AbstractNatural fibers are a sustainable alternative to synthetic fibers due to their high weight‐specific Young's moduli and strengths. However, the mechanical properties of natural fibers are very sensitive to their moisture content. Therefore, chemical treatments are often applied to natural fibers to lower their water absorption and enhance fiber‐matrix interaction. The aim is to study the effects of fiber modifications with sodium hydroxide, silane, and siloxane on the water uptake and tensile properties of flax fiber composites produced via prepreg technology. In addition, the effect of moisture on the composites' tensile properties was investigated by conditioning one part of the tensile specimens according to DIN EN 2823 (at 70°C and 85% relative humidity). The NaOH treatment was the only modification that had positive effects on the Young's modulus and tensile strength in the unconditioned and conditioned state. The increase of the tensile modulus and strength are most likely due to changes in flax fiber composition, crystallinity of the cellulose and the rougher fiber surface of NaOH modified fibers. This shows that chemical treatment of natural fibers may improve the performance level of natural fiber composites and prevent a loss in their mechanical properties in humid environments.Highlights Flax fiber modifications with sodium hydroxide, silane, and siloxane. Flax fiber composite production via prepreg technology. Water uptake after conditioning at 70°C and 85% relative humidity. Tensile tests before and after conditioning. SEM images of modified flax fibers.

Impact of NaOH Treatment on the Chemical, Structural, Physico-mechanical, and Thermal Characteristics of Jute Species

Impact of NaOH Treatment on the Chemical, Structural, Physico-mechanical, and Thermal Characteristics of Jute Species

Influence of Alkali Treatment on Bamboo/Coconut Husk Hybrid Fibre Polyester Composite

This research addresses the importance of hybrid composites in material science, specifically, demonstrating the effective reinforcement of unsaturated polyester with bamboo and coconut husk fibre through alkali treatment. The primary problem this work aims to solve is the improvement of the mechanical properties of unsaturated polyester by combining it with bamboo and coconut husk fibres which contain both lignocellulosic and cellulose fibres. Alkali treatment, particularly, sodium hydroxide (NaOH) solution, was used in this study due to its cost-effective nature and its ability to enhance the strength of both individual fibres and resulting composite. The effect of NaOH treatment with concentrations ranging from 2 – 10 wt.% on dried hybrid fibres was investigated. Chemically treated fibre composites were discovered to have improved mechanical characteristics as both tensile tests and thermogravimetric analysis (TGA) showed higher strength and thermal stability after being treated. Notably, findings identified an optimal content of 8 wt.% NaOH solution for surface modification, showcasing the potential for using NaOH-treated waste fibres to reinforce polyester resin. The implications of this study extend to a promising avenue for enhancing the performance and application of natural fibre-reinforced composites. The insights provided here offer a foundation for advancing the utilization of hybrid composites.

An Experimental Study on the Hardness, Inter Laminar Shear Strength, and Water Absorption Behavior of Habeshian Banana Fiber Reinforced Composites

ABSTRACT The current study examines the effect of NaOH treatment on the hardness, inter-laminar shear strength (ILSS) and water absorption behavior of epoxy composites reinforced with banana pseudostem fibers. Using the hand-lay-up method, six distinct samples are created that are composed of layers of woven and short banana fibers in both a plain and hybrid form. Plain- treated woven composites reveal the highest hardness and ILLS properties followed by the hybrid and short fiber composites. The random orientation of the fiber structure in short fiber composites results in the largest moisture absorption; this behavior is further supported by elucidating the kinetic parameters and diffusion coefficient parameters. SEM analysis confirms the improved surface of the NaOH-treated composite material.

Paediatric pulmonary disease-are we diagnosing it right?

It has been reported that differential diagnosis of bacterial or viral pneumonia and tuberculosis (TB) in infants and young children is complex. This could be due to the difficulty in microbiological confirmation in this age group. In this study, we aimed to assess the utility of a real-time multiplex PCR for diagnosis of respiratory pathogens in children with pulmonary TB. A total of 185 respiratory samples [bronchoalveolar lavage (15), gastric aspirates (98), induced sputum (21), and sputum (51)] from children aged 3-12 years, attending tertiary care hospitals, Chennai, India, were included in the study. The samples were processed by N acetyl L cysteine (NALC) NAOH treatment and subjected to microbiological investigations for Mycobacterium tuberculosis (MTB) diagnosis that involved smear microscopy, Xpert® MTB/RIF testing, and liquid culture. In addition, DNA extraction from the processed sputum was carried out and was subjected to a multiplex real-time PCR comprising a panel of bacterial and fungal pathogens. Out of the 185 samples tested, a total of 20 samples were positive for MTB by either one or more identification methods (smear, culture, and GeneXpert). Out of these 20 MTB-positive samples, 15 were positive for one or more bacterial or fungal pathogens, with different cycle threshold values. Among patients with negative MTB test results (n = 165), 145 (87%) tested positive for one or more than one bacterial or fungal pathogens. The results suggest that tuberculosis could coexist with other respiratory pathogens causing pneumonia. However, a large-scale prospective study from different geographical settings that uses such simultaneous detection methods for diagnosis of childhood tuberculosis and pneumonia will help in assessing the utility of these tests in rapid diagnosis of respiratory infections.

Assessment of mechanical and physicochemical properties of palm fiber composites: Effect of alkaline treatment and volume alterations

This study assesses the impact of alkaline treatments and volume fractions on biocomposites composed of a high-density polyethylene (HDPE) matrix reinforced with date palm tree fibers (FPDS). Tensile tests were conducted on both untreated and NaOH-treated biocomposites. Additionally, fiber analysis was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results reveal higher strength and stiffness compared to HDPE, albeit with limited plasticity making the material brittle. The NaOH treatment enhances certain mechanical properties. Further assessments encompassed hardness, density, melt index, and Izod impact tests. Two volume fractions, 20% and 25%, of FPDS were tested. The study establishes a correlation between empirical predictions and artificial neural network (ANN) models. Notably, an ANN architecture consisting of two input factors, 10 hidden nodes, and one output provides the analysis of mechanical properties. This investigation highlights the potential of FPDS-reinforced HDPE biocomposites, emphasizing their mechanical performance under various treatments and fiber levels.

Optimized machine learning with hyperparameter tuning and response surface methodology for predicting tribological performance in bio‐composite materials

AbstractThis study investigates the influence of NaOH treatment on tribological behavior in hybrid fiber‐reinforced composites, specifically employing Banana fiber with Al2O3 filler in an epoxy matrix. Through design of experiments (DOE), disc speed, wear duration, and NaOH treatment are analyzed for specific wear rate (SWR) and coefficient of friction (COF). To advance the understanding of wear characteristics, the study leverages advanced machine learning, using Python‐powered artificial neural networks (ANN), is integrated with innovative ANN hyperparameter optimization. Optimized parameters (1050 rpm, 60 s, 5% treatment) significantly minimize SWR (12.38 × 10−5 mm3/Nm) and COF (0.2). Scanning electron microscopy (SEM) analysis reveals improved interfacial adhesion and identifies micro‐cracks as the primary wear mechanism. This work contributes to a profound understanding of wear in hybrid composites, offering a fine‐tuned predictive model for optimizing tribological behavior and advancing material science and engineering.Highlights Reduced SWR, COF in composites via NaOH optimization. DOE: Explored disc speed, duration, NaOH impact. Advanced machine learning techniques enhanced wear prediction. Innovative: ANN hyperparameter optimization. Optimal Parameters: 1050 rpm, 60 s, 5% treatment.

Effect of NaOH and Thermal Treatment on Purifying Iron-Rich Hematite Ore

Effect of NaOH and Thermal Treatment on Purifying Iron-Rich Hematite Ore

Assessing the impact of alkali pretreatment of rice husk on its composition and product portfolio: Tradeoff between biogas and valuable materials recovery for sustainability

The burning of agricultural crop residues has evolved into a significant global issue with far-reaching implications for public health and environmental integrity. Utilizing biochemical methodologies to valorize these residues presents a dual advantage, mitigating disposal challenges while concurrently fostering wealth generation through bioenergy production and the creation of value-added materials. Nevertheless, the biodegradation of residues faces impediments due to the presence of recalcitrant silica and lignin. To assess the efficacy and elucidate the performance of biochemical approaches, this study investigates the impact of NaOH treatment (2%, 4%, 6%, 8%, and 10% w/v) on rice husk (RH) at 90 °C for 2 h initially followed by anaerobic digestion (AD) for biogas generation. This recovers silica, yielding residual pulp devoid of lignin, a raw material for biogas generation. Analytical investigation through FE-SEM reveals mild fissures and surface ruptures in 4% NaOH-treated RH, while XRD shows a crystallinity index increase from 43.3% (untreated RH) to 69.4% (NaOH-treated RH). The optimal NaOH concentration, yielding 0.16 g/g of silica and 0.206 L/g VSadded of biogas is 4%. These results highlight tailored NaOH's potential for enhancing silica recovery and biogas production from RH. Spearman's correlation analysis reveals a strong correlation (0.9–1.0) among the reduction in volatile solids (VS %), total solids (TS %), methane yield (mL/g VSadded), and biogas yield (mL/g VSadded). P values for artificial neural network (ANN) and fuzzy models consistently range from 10−4 to 10−19. Achieving sustainability necessitates balancing the trade-off between maximizing biogas production and optimizing silica recovery for an environmentally sound and efficient system.

Utilizing Alkali Pre- Treated Banana Waste in Sustainable Particleboard Manufacturing

Banana (Musa acuminata) cultivation and trade are widespread across various regions and countries globally. Nonetheless, substantial quantities of waste, primarily comprising leaves and stems of the banana plant, are annually disposed of into the environment post-harvest. This study aims to highlight this issue and propose an alternative solution in response to the escalating demand for raw materials. To this end, alkaline pretreatment was administered to particles derived from banana waste leaves and stems using NaOH solutions at concentrations of 1%, 3%, and 5%, followed by board production. Results indicate that water absorption (WA) and thickness swelling (TS) values of the produced boards increased with alkaline treatment. However, the mechanical properties stipulated in the TS-EN 312 (2012) standard were satisfactorily achieved with 1% NaOH treatment, while higher concentrations adversely affected internal bond strength (IB), modulus of elasticity (MOE), and modulus of rupture (MOR). In the surface properties tests of the boards, increasing the alkali concentration decreased values of the surface roughness and the contact angle. Overall, the findings suggest the viability of utilizing banana waste as an alternative resource.

Ultrasonication‐assisted alkali treatment of hemp fibers to improve the fiber/matrix interface of hemp/epoxy composites: The influence of sodium dodecyl sulfate surfactant

AbstractAlkali pretreatment of fibers is an efficient technique to enhance fiber/matrix bonding in natural fiber composites. This study investigates if the addition of sodium dodecyl sulfate (SDS) surfactant increases the efficacy of alkali treatment of hemp fibers. SDS concentrations ranging between 2 and 10% wt/wt were used with a constant (10% wt/wt) NaOH concentration. Fiber surfaces were observed with scanning electron microscopy (SEM). Fiber surfaces were cleaner when SDS was used compared with alkali treatment with no SDS added indicating the elimination of substances such as lignin, waxes, hemicelluloses, and pectin. Fourier‐transform infrared spectroscopy and TGA studies also confirmed the removal of these substituents. Mechanical performance of the composites was evaluated via static and dynamic tests. The tensile strength and modulus improved 24.9% and 13.6% respectively with the addition of 10 wt% SDS. The flexural strength and modulus also showed an improvement of 22.4% and 26.3% respectively when 10 wt% SDS was added to alkali solution. Dynamic mechanical tests showed that the storage and loss modulus of the composites increase with SDS/alkali treatment. Results indicated that the use of SDS in alkali treatment notably improves the composite performance which is attributable to more efficient elimination of noncellulosic constituents from fiber structure.Highlights Sodium dodecyl sulfate (SDS) improves the efficacy of NaOH treatment of hemp. Removal of noncellulosic substances from fibers was facilitated by SDS. Ultrasound/SDS assisted alkalization of fibers improved composite properties.

Study on NaOH improving the surface morphology of three-dimensional printed poly- L- lactic acid mesh scaffolds

To explore the effect of NaOH on the surface morphology of three-dimensional (3D) printed poly- L-lactic acid (PLLA) mesh scaffolds. The 3D printed PLLA mesh scaffolds were prepared by fused deposition molding technology, then the scaffold surfaces were etched with the NaOH solution. The concentrations of NaOH solution were 0.01, 0.1, 0.5, 1.0, and 3.0 mol/L, and the treatment time was 1, 3, 6, 9, and 12 hours, respectively. There were a total of 25 concentration and time combinations. After treatment, the microstructure, energy spectrum, roughness, hydrophilicity, compressive strength, as well as cell adhesion and proliferation of the scaffolds were observed. The untreated scaffolds were used as a normal control. 3D printed PLLA mesh scaffolds were successfully prepared by using fused deposition molding technology. After NaOH etching treatment, a rough or micro porous structure was constructed on the surface of the scaffold, and with the increase of NaOH concentration and treatment time, the size and density of the pores increased. The characterization of the scaffolds by energy dispersive spectroscopy showed that the crystal contains two elements, Na and O. The surface roughness of NaOH treated scaffolds significantly increased ( P<0.05) and the contact angle significantly decreased ( P<0.05) compared to untreated scaffolds. There was no significant difference in compressive strength between the untreated scaffolds and treated scaffolds under conditions of 0.1 mol/L/12 h and 1.0 mol/L/3 h ( P>0.05), while the compression strength of the other treated scaffolds were significantly lower than that of the untreated scaffolds ( P<0.05). After co-culturing the cells with the scaffold, NaOH treatment resulted in an increase in the number of cells on the surface of the scaffold and the spreading area of individual cells, and more synapses extending from adherent cells. NaOH treatment is beneficial for increasing the surface hydrophilicity and cell adhesion of 3D printed PLLA mesh scaffolds.

Drying Shrinkage and Mechanical Strength of Cementitious Composites with Alkali-Treated Makino Bamboo Fibers

ABSTRACT Alkali-treated bamboo fibers (AFs) treated with different NaOH concentrations (5 and 10%) and treatment times (1, 12, and 24 h) were used as fillers to fabricate cementitious composites with AFs (CAFs) in the present study. The results demonstrated that alkali treatment caused the partial decomposition of hemicellulose and lignin and an increase in the surface roughness of bamboo fibers. Additionally, the amounts of calcium hydroxide in alkali-treated CAFs were higher than in untreated CAFs, and they increased with increasing NaOH concentration and treatment time. For drying shrinkage (DS) under 75% relative humidity (RH), the DS values of the CAFs significantly decreased after adding AFs compared to the DS values of untreated CAFs. Compared to untreated CAFs, the density of the 5% and 10% NaOH-treated CAFs with longer treatment times decreased by 2.9% and 5.1%, respectively. Furthermore, the tensile strength of all alkali-treated CAFs exhibited no significant differences when compared with that of untreated CAFs, while the modulus of rupture and compressive strength were significantly decreased by NaOH treatment. These results indicated that the AFs significantly improved the drying shrinkage of the CAFs and hydration retardation effect of cement pastes, while the density and mechanical strength of the CAFs decreased.

Briquetting as a source pretreatment strategy to improve energy recovery from the anaerobic digestion of agricultural straw: Experimental and economic evaluation

The sustainability of biogas production from straws is limited by the collection, transportation, storage, and pretreatment of feedstocks. To address these constraints, this study investigated briquetting as a pretreatment strategy for rice straw (RS) to increase bioenergy generation. The results indicated that briquetted RS yielded 205.4 mL/g VS of methane, which was 11.7% higher compared to that produced by the untreated RS. The economic analysis revealed that the briquetting process had positive effects with a payback time of 3.4 y and an internal rate of return of 23.4%. It also reduced feedstock transportation and storage costs by 42.6%. Adding a NaOH treatment to the briquetting process increased methane production by 26.4% compared to untreated RS. However, the integration of briquetting with NaOH treatment might be an unprofitable method for processing RS. This became apparent when examining the production cost, which stood at 1.13 $/kg biomethane with an internal rate of return of 16.2%, representing an 8.7% increase and a 7.2% decrease, respectively, compared to the mono briquetting method. These results revealed that briquetting as a source pretreatment strategy can improve the productivity of straw biogas plants, thereby advancing the industry towards cleaner production.

Low-temperature and low-concentration sodium hydroxide pretreatment for enhanced enzyme hydrolysis rate from Quercus variabilis Blume

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.

Viability Study of Serra da Estrela Dog Wool to Produce Green Composites.

The environmental emergency has alerted consumers and industries to choose products derived from renewable sources over petroleum derivatives. Natural fibers of plant origin for reinforcing composite materials dominate the field of research aiming to replace synthetic fibers. The field of application of green dog wool composite materials needs to be reinforced and proven, as the industry is looking for more sustainable solutions and on the other hand this type of raw material (pet grooming waste) tends to grow. Hence, in the present work, the feasibility of applying natural fibers of dog origin (mainly composed by keratin) in green composites was studied. The green composites were developed using chemically treated dog wool of the breed Serra da Estrela (with NaOH and PVA) as reinforcement and a green epoxy resin as a matrix. The chemical treatments aimed to improve adhesion between fibers and matrix. The fibers' composition was determined using X-ray Diffraction (X-RD). Their morphology was determined using a scanning electron microscope (SEM). The wettability of the fiber was also evaluated qualitatively by analyzing drops of resin placed on the fibers treated with the different treatments. The mechanical properties of the composites were also studied through mechanical tensile, flexural, and relaxation tests. Overall, the best results were obtained for the dog wool fibers without treatment. The tensile and flexural strength of this biocomposite were 11 MPa and 26.8 MPa, respectively, while the tensile and flexural elastic modulus were 555 MPa and 1100 MPa, respectively. It was also possible to verify that the PVA treatment caused degradation of the fiber, resulting in a decrease in mechanical tensile strength of approximately 42.7%, 59.7% in flexural strength and approximately 59% of the stress after 120 min of relaxation when compared to fiber made from untreated dog wool. On the other hand, the NaOH treatment worked as a fiber wash process, removing waxes and fats naturally present on the fiber surface.

Investigation of viscoelastic behavior of Abaca-reinforced epoxy composites

Natural fiber-based composites demonstrate excellent and comparable static and dynamic mechanical properties to conventional materials, such as steel and aluminum. They also extend their applications to aeronautical, sports equipment, and marine fields. This experimental study aims to find the effect of untreated and treated Abaca-reinforced epoxy composites on the viscoelastic behavior and the optimum combinations of fiber and resin to produce better bonding efficiency. The different specimens used for this study were pure epoxy, untreated, and chemically treated composite specimens. The four weight percentages of Abaca fibers are 10%, 20%, 30%, and 40% used to prepare composite specimens. Similarly, four different sodium hydroxide (NaOH) concentrations, 4, 6, 8, and 10 wt. %/vol. %, have been used for the chemical treatment of fibers. The storage modulus of Abaca-reinforced epoxy composite specimen has been investigated with respect to temperature and fiber content. The result shows that the 30% weight fraction of fibers with chemically (8 wt. %/vol. %) treated fiber-reinforced epoxy specimen produces 41.67% higher storage modulus than the 10% weight fraction of fibers content of composite specimens. Fourier-Transform Infrared Spectroscopy (FTIR) broad transmittance has been used to distinguish the raw and chemically treated fibers. FTIR results reveal the removal of functional groups after NaOH treatment.

The Influence of Treatment Methods on Bending Mechanical Properties of Bamboo Strips

This study aimed to obtain a comprehensive understanding on bamboo as a curve-member manufacturing material by comparative analysis of how different treatment methods on bending properties improve the effect on bamboo strips. In order to achieve this purpose, bamboo strips were subjected to water boiling, 15% NaOH, and 25% NH3 impregnation; the impact of physical, mechanical and chemical properties were explored. The results revealed that: (1) Water boiling significantly affected crystallinity, cellulose, and lignin content, with a treatment duration of 10 h showing the most favorable results for flexibility and plasticity, greatly improving bending performance. (2) An amount of 15% NaOH treatment significantly increased bending MOE and plastic displacement by 73% and 122.7%. However, it led to a noticeable decrease in bending strength (MOR). A treatment above 8 h could cause irreversible damage to bamboo strips. (3) The improvement of 25% NH3 on bamboo bending ability was lower than water boiling. The effects of chemical composition were obvious in the initial five days and changed little after five days. Generally, water boiling for over 10 h is suitable for applications with significant bending requirements. While for maintaining bamboo color, original strength, and bending performance, 25% NH3 for five days was recommended, and 15% NaOH was not advised for improving bamboo bending performance and its applications.