Sodium Hydroxide Treatment Research Articles

Investigation of the biological removal of nickel and copper ions from aqueous solutions using mixed microalgae

AbstractThe use of mixed microalgae offers an effective solution for the management of contamination risks in cultivation while enhancing economic viability. In this study, mixed microalgae were used for the first time for the removal of copper (Cu) and nickel (Ni) from aqueous solutions. The characteristics of the adsorbents were examined thoroughly, and the adsorption process was assessed using isotherms, kinetics, and thermodynamics. Particle size, concentration, contact time, temperature, and pH were among the variables assessed. The findings demonstrated that, at an initial concentration of 100 mg L–1 and a pH of 6, the maximum adsorption of Cu with a particle size of 1 mm (90.20%) took place in 60 min. The highest adsorption rate (78.25%) was found for Ni. Microalgae performed best over 180 min at room temperature and at pH values that promoted metal dissolution. The removal percentages of wet and dried microalgae were comparable, and the wet adsorbent was more economical. It was feasible to remove both metals at the same time. Up to three cycles of adsorbent reuse were possible, with sodium hydroxide treatment offering superior removal to hydrochloric acid. Thermodynamic analysis demonstrated that this process, which results in a disordered state, is exothermic and spontaneous.

Thermal Performance Of Termite Mold Bricks Reinforced With Empty Fruit Bunch Spikelet And Coconut Fibers

The use of natural fibers to enhance the thermal properties of earth bricks has become increasingly popular. This study investigates the thermal performance of termite mold soil (TMS) reinforced with two types of fibers: coconut fibers (CF) and empty fruit bunch spikelet fibers (EFBSF). Various fiber compositions (0%, 0.5%, 1%, 1.5%, 2%, and 2.5%) were combined with sodium hydroxide (NaOH) treatments at concentrations of 1%, 2%, 3%, and 4%. Laboratory results reveal that TMS exhibits promising physical properties, including a moisture content of 23.64%, a maximum dry density of 1.63 g/cm³, and a plasticity index of 20%, indicating its structural stability and suitability for earth block production. The study also analyzes the chemical properties of EFBSF and CF fibers, noting that CF has a higher holocellulose content (88.0%) compared to EFBSF (33.5%), which impacts moisture retention and structural integrity. Thermal analysis demonstrates that incorporating these natural fibers significantly enhances the thermal performance of TMS. With a 2.5% fiber content, CF reduces thermal effusivity from 1771.43 J/m²Ks^1/2 to 1079.39 J/m²Ks^1/2 and thermal conductivity from 0.86 W/mK to 0.38 W/mK, making it particularly effective in improving insulation in hot conditions. EFBSF also lowers thermal effusivity and conductivity, but to a lesser extent than CF. Additionally, the presence of these fibers reduces volumetric calorific capacity, with CF showing a more pronounced effect. Overall, TMS reinforced with coconut fibers, especially at 1% NaOH and 2.5% fiber content, offers the best thermal performance, suggesting its potential for sustainable construction. This research promotes the use of locally sourced, natural fibers in earth block manufacturing, contributing to the development of more energy-efficient and environmentally friendly building materials.

Investigation on Erosion Resistance in Polyester-Jute Composites with Red Mud Particulate: Impact of Fibre Treatment and Particulate Addition.

This research investigates the manufacturing and characterisation of polyester-based composites reinforced with jute fibres and red mud particulates. The motivation stems from the need for sustainable, high-performance materials for applications in industries, like aerospace and automotive, where resistance to erosion is critical. Jute, a renewable fibre, combined with red mud, an industrial byproduct, offers an eco-friendly alternative to conventional composites. The composites were fabricated using compression moulding with varying red mud contents (10, 20, and 30 wt.%) and a fixed 40 wt.% of jute fibre. Fibre treatments included sodium hydroxide (NaOH) and silane treatments to improve bonding and performance. Erosion tests were performed using an air-jet erosion tester, examining the effects of the red mud content, fibre treatment, and impact angles. Scanning Electron Microscope (SEM) analysis provided insights into the erosion mechanisms. A distinctive reduction in erosion rates at higher impact angles (30°-60°) was observed, attributed to the semi-ductile nature of the composites. The addition of red mud enhanced erosion resistance, although an excess of 30 wt.% reduced resistance due to poor surface bonding. Silane-treated composites showed the lowest erosion rates. This study provides new insights into the interplay among material composition, fibre treatment, and erosion dynamics, contributing to the development of optimised, eco-friendly composite materials.

Tensile Properties of Open Hole and Unhole Sugar Palm ‘Ijuk’ (SPI) Fibre Composite Treated with Sodium Hydroxide (NaOH)

This study evaluates the effects of sodium hydroxide (NaOH) treatment on tensile properties of sugar palm 'ijuk' (SPI) fibre-reinforced polymer (FRP) composites, with and without an open hole that acts as a stress concentrator. The NaOH treatment is aimed to improve the interfacial adhesion between SPI fibres and polymer matrix. Composite specimens were prepared using the hand lay-up method, incorporating SPI fibres in various orientations, and featuring a 6 mm diameter hole. Tensile tests were conducted to evaluate the mechanical performance of SPI FRP composite, including ultimate tensile strength, Young's modulus, and elongation at break. The research also compared the properties of SPI to those of synthetic glass fibre in fibre-reinforced polymer composites. The results showed that NaOH treatment significantly improves the fibre-matrix adhesion with 26% increase in tensile strength, leading to enhanced tensile properties in both samples, regardless of hole presence. The 0° orientation provides the highest strength and stiffness when the load is applied in the direction of the fibres. While for the 90° orientation, strength reduces by 14%. The impact of the hole on stress concentration and the subsequent mechanical behaviour of the open-hole specimens is substantial. The findings of this study offer insightful perspectives on the potential use ofNaOH-treated SPI fibre in structural and other applications, demonstrating its ability to withstand tensile stresses, even with geometric discontinuities like holes.

Research on the Cell Wall Breaking and Subcritical Extraction of Astaxanthin from Phaffia rhodozyma.

This study focused on developing an effective cell wall-breaking method for Phaffia rhodozyma, followed by utilizing subcritical fluid extraction to isolate, extract, and concentrate astaxanthin from the complex fermentation products of P. rhodozyma. A comprehensive comparison of seven distinct methods for disrupting cell walls, including dimethyl sulfoxide treatment, lactic acid treatment, sodium hydroxide treatment, β-glucanase enzymatic digestion, β-mannanase enzymatic digestion, and a combined enzymatic treatment involving both β-mannanase and β-glucanase was conducted. The results identified the lactic acid method as the most effective in disrupting the cell walls of P. rhodozyma. The software, Design Expert, was used in the process of extracting astaxanthin from cell lysates using a subcritical extraction method. Through fitting analysis and response surface optimization analysis by Design Expert, the optimal extraction conditions were determined as follows: an extraction temperature of 41 °C, extraction frequency of two times, and extraction time of 46 min. These parameters facilitated the efficient extraction, concentration, and enrichment of astaxanthin from P. rhodozyma, resulting in an astaxanthin concentration of 540.00 mg/L. This result can establish the foundation for its high-value applications.

Selective conversion of spent cracking catalyst to faujasite-structured zeolites

Current recycling strategies for spent catalyst in Fluid Catalytic Cracking (FCC) focus on valuable rare-earth elements (REE) and sometimes include a reuse of spent materials by down-cycling, which hinders a circular economy. Herein, a new procedure for the selective conversion of spent FCC catalysts to FAU-type zeolite without secondary crystalline phases such as sodalite, zeolite P or zeolite A is reported. The steps include a leaching process of REE, followed by thermal activation with sodium hydroxide and acid treatment to get an aluminum-rich feed. The synthesis of FAU-type zeolites with varying Si/Al ratios uses the aluminum-rich catalyst feed and commercial water glass. The experiments show that incorporation of silicate from water glass into the zeolite structure is limited to zeolite products with Si/Al ratio ≤ 2.0. It indicates a flocculation of silicates in higher concentration in competition to the crystallization process of FAU-type zeolites. This is reinforced by the resulting crystals, covered and surrounded with small particles with morphology of silica. Moreover, a clear differentiation between zeolite Y and zeolite X is possible from materials properties with the definite evidence of a mixed phase. The kinetics of feed dissolution and incorporation of impurities, alumina and silica are controlled by the pre-treatment temperature, duration and silicon source. This enables flexible adjustment of the aluminum re-use from spent FCC catalyst, the amount of foreign elements (Fe, Ni, V), phase purity, Si/Al ratio, specific surface area and thermal stability of the final zeolite product. Structural and textural data of the resulting zeolites reveals high crystallinity > 80 %, Si/Al ratios of 1.6–2.0, and specific surface areas up to 780 m2/g.

Exploring the potential of agricultural waste enset fibers reinforced poly lactic acid biocomposites

This study explores the environmental sustainability of composite materials by reinforcing agricultural residue enset fiber as a potential reinforcement. Initially, enset fibers underwent a 5 wt% sodium hydroxide treatment to eliminate impurities and enhance fiber-matrix adhesion in the subsequent biocomposite fabrication process. Various enset fiber-to-polylactic acid ratios were blended and opened to enset/PLA fibers mat using a fiber carding machine, and the resulting biocomposite material was prepared through the hot press. A comprehensive assessment covering mechanical, thermal, dynamic mechanical, water absorption, and morphological properties was conducted on the enset/PLA biocomposites. The results showed increased mechanical (tensile strength of 24.12 MPa, bending stress of 33.02 MPa, flexural modulus of 2.01 GPa, the impact resistance of 12 kJ/m2) and thermomechanical properties with increased enset fiber loading, with optimum value at a 30 % weight percentage. The Differential scanning calorimetry results showed the addition of enset fiber increases the glass transition temperatures and degree of crystallinity. SEM images confirmed robust adhesion between enset fibers and PLA. This study highlights the potential applications of enset/PLA composites in automotive, furniture, packaging, and diverse industries, emphasizing their promising role in sustainable material development.

Agrocybe cylindracea Dietary Fiber Modification: Sodium Hydroxide Treatment Outperforms High-Temperature, Cellulase, and Lactobacillus Fermentation.

Agrocybe cylindracea dietary fiber (ADF) contains 95% water-insoluble dietary fiber, resulting in poor application performance. To address this issue, ADF was modified by four methods (cellulase, sodium hydroxide, high-temperature, and Lactobacillus fermentation) in this paper. By comparing the physicochemical properties, microstructures, monosaccharide compositions, and functional characteristics (antioxidant and α-glucosidase inhibitory activities in vitro) of all modified ADF samples, the optimal modification method was selected. Results showed that sodium hydroxide treatment was deemed the most effective modification method for ADF, as alkali-treated ADF (ADF-A) revealed a higher oil-holding capacity (2.02 g/g), swelling capacity (8.38 mL/g), cholesterol adsorption (6.79 mg/g), and α-glucosidase inhibitory activity (more than 70% at 0.4-0.6 mg/mL) than the other modified samples. The looser microstructure in ADF-A might be attributed to molecular rearrangement and spatial structure disruption, which resulted in smaller molecular sizes and decreased viscosity, hence improving ADF's physicochemical and functional qualities. All these findings indicate the greater application potential of modified ADF products in food and weight-loss industries, providing a comprehensive reference for the industrial application of ADF.

Advancements in chemical modifications using NaOH to explore the chemical, mechanical and thermal properties of natural fiber polymer composites (NFPC)

Abstract Increasing environmental awareness and concerns about global warming have resulted in a significant demand for sustainable and eco-friendly resources, such as naturally available fibers, that can be suitable alternatives to petroleum/synthetic materials such as glass, carbon and Kevlar in reinforced composites. The exploration of natural fibers as reinforcements in composites is increasing in popularity, particularly in the development of transport and household components. However, natural fibers also have a few limitations that should be addressed appropriately, including lack of compatibility between fiber-matrix, fiber swelling, excess absorption of moisture, resistance to chemicals and fire. Consequently, various processes have been used to improve the fiber surface, to obtain a better fiber–matrix interface. The primary objective of this work is to review the impact that a 5 % NaOH (sodium hydroxide) treatment has on the chemical, mechanical, and thermal properties of natural fiber-reinforced composites (NFRC).

Development of Green Composite Utilizing Sisal Strands and Sustainable 3-D Printed PLA Layers

PLA/Sisal hybrid composites have been used in cars and technical textile applications. When utilized in composites, 3-D-printed PLA layers can improve performance and homogeneity. The primary goal of this research was to use sisal and 3-D-printed polylactic acid (PLA) layers to develop a sustainable bio-composite. To enhance the bonding of sisal fibres with the PLA matrix, sisal fibres were given a sodium hydroxide treatment. This would improve the mechanical and thermal properties of composites. Sisal fibre (between 4 wt% and 8 wt%), epoxy concentration (between 85 wt% and 90 wt%), and PLA 3-D printing infilling percentage (between 90 wt% and 100 wt%) were the independent parameters. The Taguchi L8 orthogonal array design was used to make the composite samples. The changes in the amounts of PLA infill, epoxy matrix concentration, and sisal fibre content were considered for test sample development. The optimal settings for improving their tensile, flexural, and impact capabilities were determined by analyzing their signal-to-noise ratio (S/N). The PLA/sisal fibre composite showed a remarkable level of mechanical properties in Sample 8, surpassing those of the other samples. To improve mechanical and thermal properties, the appropriate values for sisal fibre composition, PLA infilling percentage, and epoxy concentration percentage were 8 per cent, 95 per cent, and 85 per cent, respectively. After testing, the tensile (293–295.4 Megapascal) (Mpa), impact (2.73–4.84 Mpa), and flexural strength (188.5–270.4 Mpa) results show that the new composite has better mechanical behaviour properties. Additionally, FTIR, SEM, and DSC experiments were run to examine the composite's structural characteristics. Using less volatile epoxy resin, a sustainable 3-D-printed PLA layer and Sisal fibre bio-composite were developed.

Characterization and isolation method of Gigantochloa scortechinii (Buluh Semantan) cellulose nanocrystals

This study explored the impact of sodium hydroxide and benzoylation treatment on the production of cellulose nanocrystals from Semantan bamboo (Gigantochloa scortechinii). Bamboo cellulose nanocrystals (BCNs) were obtained via acid hydrolysis, with the effectiveness of an isolation method and chemical treatments demonstrated in removing non-cellulosic constituents. X-ray diffraction analysis revealed a crystalline cellulose II structure for benzoylated BCN (B) and a crystalline cellulose I structure for NaOH-treated BCN (S), with BCN (S) exhibiting a higher crystallinity index (80.55 %) compared to BCN (B) (67.87 %). The yield of BCN (B) (23.68 ± 1.10 %) was higher than BCN (S) (20.65 ± 2.21 %). Transmission electron microscopy images showed a mean diameter of 7.95 ± 2.79 nm for BCN (S) and 9.22 ± 3.38 nm for BCN (B). Thermogravimetric analysis indicated lower thermal stability for BCN (B) compared to BCN (S), with charcoal residues at 600 °C of 31.06 % and 22 %, respectively. Zeta potential values were −41.60 ± 1.97 mV for BCN (S) and −21.80 ± 2.54 mV for BCN (B). Gigantochloa scortechinii holds significant potential for sustainable and eco-friendly applications in the construction, furniture, and renewable energy industries. These findings highlight the versatility and potential of BCNs derived from Gigantochloa scortechinii for various applications.

Enhancing tribological performance of hybrid fiber-reinforced composites through machine learning and response surface methodology

This study delves into the significant effects of sodium hydroxide (NaOH) treatment on the tribological properties of hybrid fiber-reinforced composites, specifically focusing on the combination of paddy straw (PS) and pineapple leaf (PALF) in a polyester matrix. By leveraging Artificial Neural Networks (ANNs) to predict the Specific Wear Rate (SWR) and Coefficient of Friction (COF), the research employs a grid search approach for hyperparameter optimization. This optimization process results in an optimal ANN architecture with impressive accuracy, showcasing low mean absolute error and high R-squared values of 0.991 and 0.986 for SWR and COF predictions, respectively. Utilizing the Design of Experiments (DOE), the study systematically analyzes the intricate interplay of disc speed, wear duration, and NaOH treatment percentage, with a specific focus on SWR and COF as pivotal tribological metrics. The Analysis of Variance (ANOVA) results underscore the substantial impact of duration and treatment percentage on wear characteristics. Additionally, quadratic regression models reveal nuanced correlations, highlighting the sensitivity of SWR to NaOH percentage and the influence of disc speed, duration, and treatment percentage on COF. This outcome emphasizes the efficacy of these parameters in achieving superior tribological performance in hybrid composites. Beyond contributing to a profound understanding of wear characteristics, this work introduces an innovative dimension through optimized ANN modeling, ensuring a more accurate and fine-tuned predictive model.

Effect of alkaline treatment on hard vegetable shells on the properties of biobased abrasive wheels

One of challenges in composites research is to improve the quality of the interface fillers-matrix. The aim of this study was to evaluate the effect of sodium hydroxide (NaOH) treatment of coconut shells and palm kernel shells on the properties of wheels made. Shells were treated at concentrations of 1 %, 5 % and 10 % for 90 min before being used as abrasive grains to reinforce an epoxy matrix. The thermal degradation of shells was analyzed and the morphological study shows that the treatment modifies the surface of grains. The treatment led to a reduction in the water absorption rate of more than 10 % and the porosity of the grinding wheels of around 15 %. Statistical analysis showed that the treatment improved the material removal rate and wear resistance. The wheels treated with a concentration of 1 % gave better results with removal rates of 160 mg/s and wear rates of 3.86E-05 cm3/N.m.

Production of Porous Biochar from Cowdung and its Application

Porous activated carbon (PAC) powder is prepared from solid bio-waste - cow dung samples (CD). UV- Spectroscopy confirms the absorption rate of activated porous biochar at different concentration solutions(in ppm).The activation process is carried out by phosphoric acid and sodium hydroxide treatment followed by calcination at different temperature condition. XRD pattern confirms the amorphous phase formation with graphitic nature for different precursor utilization. SEM analysis shows the uniform and hierarchical porous network formation and aggregated particle with tiny. X- ray analysis confirms the formation of graphitic carbon and porous morphology for sample activated at increased calcination temperature. The elemental composition of as prepared carbon samples is determined by SEM and confirms the formation major carbon content existence. The obtained product is observed for the dye removal process wherein the specific amount of PAC is added to the Methylene Blue(MB) dye solutions and the absorption rate is observed through uv-spectroscopy.

Effect of sodium hydroxide treatment on the fracture toughness of luffa natural fiber reinforced epoxy epikote 828

AbstractMicro‐sized luffa natural fibers (MLNFs) were derived from raw luffa natural fibers from Vietnam by undergoing treatment with sodium hydroxide. This study examined the impact of sodium hydroxide concentration, temperature, and treatment duration on the fracture toughness of epoxy resin 828 reinforced with MLNFs. The results showed that the fracture toughness of the composite, as measured by the critical‐stress‐intensity factor (KIC) and Izod impact strength, was improved after the treatment of the MLNFs with sodium hydroxide. Specifically, with the optimal sodium hydroxide treatment parameters of 6% NaOH at 70 °C for 6 h, the critical‐stress‐intensity factor increased by 93% (from 2.0 to 3.86 MPa m1/2) and the Izod impact strength rose by 44.6% (from 3.81 to 5.51 kJ/m2). The thermal properties and surface structure of MLNFs treated with NaOH were analyzed using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) images.

The hemp-reinforced polypropylene composite: Effect of the alkaline and coupling agents treatment

The hemp-reinforced polypropylene composite was produced by the twin-screw extrusion in the presence of polypropylene-graft-maleic anhydride (PP-g-MA) and silane as coupling agents and subsequence by the compression molding. The hemp fiber was obtained by sodium hydroxide treatment prior to the twin-screw extruder. The PP/Hemp composite was analyzed using a universal testing machine, scanning electron microscope, differential scanning calorimetry, X-ray diffraction, and Fourier transform infrared spectroscopy. The mechanical properties of the PP/MA/Hemp demonstrated a better result than that of PP/Si/Hemp in most hemp contents. The SEM images of the PP/MA/Hemp exhibited excellent interfacial bonding in PP/MA/Hemp30 without fiber pullouts. However, the fiber breakage and some fiber pullout with gaps around the fiber of PP/Si/Hemp indicate the poor bonding of the PP matrix. The functional group of the PP/Hemp composite showed the –OH cellulose result peak of the reaction between hemp fibers and polypropylene.

Influences of sodium hydroxide and oxalic acid treatments on physical, mechanical, thermal properties, and morphology of ramie fibers

The environmentally friendly properties of natural fibers cause their use as reinforcement in polymer matrices to continue to grow. However, its hydrophilic properties can significantly reduce interfacial interactions. Chemical treatment is one method used to reduce the hydrophilic nature of ramie fibers. This study aimed to investigate the effects on ramie fiber of three chemical treatments: oxalic acid at a concentration of 5 (wt.%), sodium hydroxide at 3, 5, and 7 (wt.%), and a combination of both treatments. Physical properties, moisture content, tensile strength, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), thermal properties, contact angle, and morphology of ramie fibers before and after treatment were observed in this investigation. FT-IR test results showed a partial loss of amorphous content and more intense cellulose peaks in treated ramie fibers. The combination treatment of alkali and oxalic acid gave the best results, which initiated the dissolution of some of the lignin, hemicellulose, and extractive content. XRD results indicated the surface treatment also led to a 20.35% rise in the crystalline index. In addition, there was a significant increase in tensile strength of 136.10 % in fibers soaked with chemicals. The morphology of the fibers with treatment showed defibrillation and loss of contaminants on the fiber surface, which was the cause of the smaller fiber diameter. Therefore, this optimum treatment is expected to improve the interfacial properties of natural fibers and polymer matrices so that they can enhance the properties of composites when applied in industries.

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.

Modified differential lysis for sexual assault samples using a combined enzymatic and alkaline approach.

Traditional sexual assault sample processing methods are time-consuming and inefficient.This modified differential lysis method produces lysates with sufficient DNA yield and quality.A combined technique using enzymatic and alkaline lysis can accomplish fractional separation.Lysis with prepGEM and NaOH absent purification is compatible with downstream processes.

Influence of Chemical Treatment on the Physical and Mechanical Properties of Bamboo Fibers as Potential Reinforcement for Polymer Composites

ABSTRACT The growing concern for environmentally friendly biomaterials has spurred interest in natural fibers as a viable alternative to synthetic fibers in various industrial applications. Chemical treatment of natural fibers is necessary in cases where it is desired to enhance their properties and make them more suitable for various industrial applications. These treatments can remove impurities, increase fiber roughness for better adhesion, and modify surface chemistry, ultimately improving characteristics like tensile strength, thermal stability, and compatibility with matrix materials in composites. In this study, chemical treatments, including Sodium Hydroxide, Ammonium Hydroxide, and Potassium Permanganate, were applied to the Bamboo fibers to modify the fiber structure. The tensile strength, morphological characteristics, and degree of crystallinity of the treated fibers were examined. Results revealed that 5% Sodium Hydroxide treatment for 2 hours significantly improved tensile strength and crystallinity compared to other treatments. Chemical composition analysis, XRD, and FTIR analyses confirmed the removal of impurities and amorphous substances. Density measurements indicated a reduction in volume due to the elimination of low molecular weight impurities, leading to increased fiber density. This research provides valuable insights for the development of sustainable biomaterials in the construction and automotive industries such as wall panels, dashboards and door panels.