Influence Of Sodium Hydroxide Research Articles

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.

Influence of sodium hydroxide on phase transformation of gamma alumina to alpha alumina

AbstractCorundum and transition alumina powders are commonly produced through the Bayer process—that is, by digestion of bauxite in a sodium hydroxide solution, followed by gibbsite precipitation, which contains significant amounts of Na+ ions. During the de‐hydroxylation of gibbsite, Na+ is associated with retardation of the structural phase transformations between transition alumina and corundum (α‐Al2O3) phases, although the exact role of Na is unclear. The influence of Na+ ions on the phase transformation of γ‐Al2O3 to α‐alumina was investigated by varying the concentration of NaOH in aqueous γ‐Al2O3 suspensions. The phase transformation behavior of γ‐Al2O3 was monitored through thermal analysis, X‐ray diffraction, scanning electron microscope, X‐ray photoelectron spectrometer (XPS), and transmission electron microscope. As the Na concentration in γ‐alumina suspensions increased, the amount of α‐Al2O3 decreased in samples that were heat treated at 1200°C for 2 h. XPS analysis indicated that washing transition alumina powders with NH4OH solutions had decreased the surface concentration of Na+ and facilitated the phase transformation to α‐Al2O3.

Cationic etherification modification of corn starch and its sizing property

In order to solve the difficulty of starch being insoluble under medium and low temperature, a cationic starch slurry modified with etherification was developed. Raw starch was hydrolyzed by sodium hydroxide to improve the dispersion performance, and then the hydrolyzed starch was endowed with cationic groups by N-2,3-epoxy-propyl trimethyl ammonium chloride to improve the dispersion stability. Through various characterization methods, it was found that the quaternary ammonium cationic starch obtained was dissolved in water at medium and low temperature, and the starch structure was changed under the influence of sodium hydroxide and N-2,3-epoxy-propyl trimethyl ammonium chloride. Furthermore, the mechanical properties and abrasion resistance of cotton yarn treated with cationic starch could be significantly improved. Compared with the original yarn, the breaking strength of the yarn treated with cationic starch was increased by 70.05%, the hairiness index of the yarn was reduced by 87.5%, the abrasion resistance was increased by 500.00%, and the stiffness decreased by 276.47%. In addition, the Zeta potential of modified starch was positive, and the degree of etherification substitution of starch ranged from 0.02 to 0.26. The preparation method of etherified starch obtained has the advantages of environmental protection, low cost, and a simple process, which provides a novel way to construct textile size.

Influence of sodium hydroxide (NaOH) molarity on fresh properties of self-compacting slag-based geopolymer concrete containing recycled aggregate

The present study is an attempt to examine the feasibility of developing a sustainable self-compacting concrete (SCC) made with geoploymer binder and recycled aggregate. The study explores the effects of four sodium hydroxide (SH) molarities (8 M, 10 M, 12 M and 14 M) on the fresh properties of self-compacting slag-based geopolymer concrete. Eight slag-based geopolymer concrete mixtures were examined. These mixes are divided into two groups: GPN group in which the mixtures are made with natural aggregate (NA) and GPR group in which the mixtures are made with recycled aggregate (RA). Each group includes four mixes made with the four mentioned SH molarities. The mixtures were examined for its flowability, passing ability, viscosity and segregation resistance and the results were tested against the EFNARC recommendations for SCC. It was concluded that recycled aggregate and the molarity of sodium hydroxide affects the fresh properties of SCC. But, developing self-compacting slag-based geopolymer concrete that meets the limits of EFNARC is feasible.

Studies on the Influence of Sodium Hydroxide Concentration on the Stress Corrosion Cracking Behavior of Modified 9Cr-1Mo (P91) Steel Weldment

Influence of sodium hydroxide (NaOH) concentration on the behavior of modified 9Cr-1Mo (P91) steel weldment with respect to stress corrosion cracking (SCC) resistance was studied in this work. Weldment of this steel was prepared using a shielded metal arc welding process using modified 9Cr-1Mo electrode followed by weld heat treatment at 1,033 K/1 h. Stress corrosion cracking experiments were performed at 473 K at a strain rate of 1 × 10−6 s−1 in millipore water (MP) (inert medium) as well as in 1 M, 2 M, 3 M, and 4 M NaOH medium. Ultimate tensile strength (UTS), yield strength (YS), and % total elongation (%TE) determined from stress-strain plots were found to decrease with increasing concentration of NaOH. The SCC susceptibility index (Iscc) evaluated using UTS and %TE was highest for the specimen tested in 4 M NaOH. The number density of cracks determined by optical microscopy increased with the concentration of NaOH. Also, it was higher in number in the base metal than in the weld metal. However, at highest concentration of 4 M NaOH, cracks were observed in the heat affected zone of the weld metal. Fractographic studies by scanning electron microscopic showed mixed mode from intergranular to transgranular cracking and vice versa at all concentrations of NaOH. Failure in the base metal was attributed to coarse precipitates, facilitating easy pitting at the precipitate/matrix interface. From the studies it was inferred that weld metal showed better resistance than base metal to SCC in 1 M to 4 M NaOH concentrations.

Extraction of natural dye from the mesocarp and exocarp of Cocos nucifera, textile dyeing, and colour fastness properties

Dyes derived from coconut (Cocos nucifera) husk have materialised as an important substitute to synthetic dyes. However, better extraction techniques are needed to leach out the natural colourants from this plant. The influence of sodium hydroxide (NaOH) concentration (0.2 to 0.8 M) and time of extraction (2 to 10 min) on the maximum extraction yield of natural dye from the mesocarp and exocarp of C. nucifera have been studied. The results indicate a significant (p < 0.05) increase in dye yield for both mesocarp and exocarp extracts when using 0.8 M NaOH for 4 min. This study had also investigated the effect of different concentrations of tannic acid as a mordant on dyeing properties and wash fastness of cotton fabrics dyed with the mesocarp and exocarp C. nucifera dyes. The dyeing process of the natural dye was performed by varying the concentrations of tannic acid (2.5%, 5.0%, and 7.5%) at 40 °C for 60 min. Pre-mordanted dyed cotton fabrics showed a deeper colour than unmordanted dyed cotton fabrics. As the concentration of tannic acid increases, the L* value decreases in all pre-mordanted fabrics. Tannic acid as a mordant exhibited better result at 7.5% concentration than the 2.5% and 5.0% concentration. The darkness and shade of the dye from the mesocarp exhibited a better outcome than the exocarp of C. nucifera and confirms that the mordant enhanced the dye hue on cotton fabric. Wash fastness properties of mesocarp dyed cotton fabrics ranged from poor (2) to good (3) depended on the tannic acid concentration used. This work suggests that mesocarp C. nucifera dye can complement synthetic dyes in the dye industries.

Influence of Sodium Hydroxide (NaOH) Treatment on Mechanical Properties and Morphological Behaviour of Phoenix sp. Fiber/Epoxy Composites

The purpose of this present research work is to assess the static and dynamic mechanical properties of an eco-friendly natural cellulosic fiber (Phoenix sp.) reinforced epoxy composites. The cellulosic fiber was isolated from Phoenix sp. plant petioles, and it was treated with various concentrations of sodium hydroxide (5, 10, 15 and 20%) solution. The impact of treatments on tensile, flexural, impact and dynamic mechanical properties of the fabricated composite was explored and optimized. Moreover, the mechanically tested samples were subjected to morphological analysis to predict the failure mechanisms. The outcomes revealed that the treated fibers had good interfacial bonding with epoxy matrix (confirmed through morphological and single fiber pull-out studies), reduced the failure mechanisms (fiber pull-outs and fiber debonding) and exhibited good static and dynamic mechanical properties of composite materials than untreated fiber composites. It is concluded that composites fabricated using 15% of sodium hydroxide treated fiber could be used to manufacture automotive panels and other lightweight industrial products.

Low-Temperature Preparation of β-C2S from Sand/Lime Mixture: Influence of Sodium Hydroxide

The low-temperature preparation of belite (β-C₂S) from a mixture of lime and white sand (Ca/Si=2) in presence of 0.5-5 M NaOH solution was investigated by hydrothermal treatment in a stainless steel

Green ethanol production from cotton stalk

This study was initiated to produce green ethanol from cotton stalk lignocelluloses using separate hydrolysis and fermentation (SHF) process. The influence of sodium hydroxide (2%) pretreatment at different residence times was also investigated. The effect of incubation period, enzyme concentration, pH and substrate concentration during enzymatic saccharification on sugar yield and ultimately on the ethanol production was studied. The results show that pretreatment with 2% NaOH for 90 min at 121°C was most effective and gave the highest percentage of cellulose (78.2±1.64%) along with highest delignification rate (63.9%). During the enzymatic saccharification, under the optimized conditions, maximum concentration of reducing sugars of the hydrolyzate was 67.83 ± 0.35 g/L with the maximum saccharification efficiency of 78.06%. The total sugars were 77.48 ± 2.37 g/L and total phenols were found to be 1.6 mm. Fermentation was carried out by using the enzymatically saccharified hydrolyzate and monoculture of Saccharomyces cerevisiae. Highest ethanol concentration of 22.93 ± 1.74 g/L with 0.36 g/g ethanol yield was achieved after 48 h of incubation at 30°C, pH 5 and 3% inoculum size.

Characterization of the Influence of NaOH Chemical Solution with Different Concentration on the Properties of Nano-Composite Materials

In this work, composites based on unsaturated polyester resin reinforced with nano-silica (0.5%, 0.7% and 1%) Sio2 were studied to determine the influence of sodium hydroxide (NaOH) chemical solution with different concentration ( 1% , 2% , 4% ,6% and 8%) wt. for a period of 24 hours under room temperature conditions on the mechanical properties of polymer matrix composite material. For this purpose, tensile and hardness taste were carried out, Since Polyester is one of most commonly used polymar matrix with reinforcing for advanced composites applications due to its low cost, easy handling, corrosion resistant, and flame retardant.

Characterization of the Influence of NaOH Chemical Solution with Different Concentration on the Properties of Nano-Composite Materials

In this work, composites based on unsaturated polyester resin reinforced with nano-silica (0.5%, 0.7% and 1%) Sio2 were studied to determine the influence of sodium hydroxide (NaOH) chemical solution with different concentration ( 1% , 2% , 4% ,6% and 8%) wt. for a period of 24 hours under room temperature conditions on the mechanical properties of polymer matrix composite material. For this purpose, tensile and hardness taste were carried out, Since Polyester is one of most commonly used polymar matrix with reinforcing for advanced composites applications due to its low cost, easy handling, corrosion resistant, and flame retardant.

Influence of sodium hydroxide on the performance and hydration of lime-based low carbon cementitious materials

To increase the recycling of industrial solid waste in cement-based materials, lime-based low carbon cementitious materials (LCM) as green binder materials have shown bright prospects. To further improve the properties of LCM, different dosages of sodium hydroxide as alkali activators were mixed with LCM in the test, and this study focused on the influence of sodium hydroxide on the performance and hydration of LCM. The strength, workability, hydration and microstructure of LCM in the presence of sodium hydroxide were investigated in detail and compared to those of the original LCM. The test results indicated that the minor amounts of sodium hydroxide remarkably improved the mechanical properties of LCM at early ages (3 and 7 days). Additionally, the further hydration of mineral admixtures was affected by the presence of sodium hydroxide, which resulted in a slight improvement of the mechanical properties of LCM at the later stage. The formation of ettringite in the hydrates of LCM was suppressed by the addition of sodium hydroxide. Moreover, the Ca/Si ratio of the C-(A)-S-H gel formed in the sodium hydroxide activated LCM was lower than that in the plain LCM, and a minor amount of C-(N)-A-S-H gel formed in the hydrated paste due to the Na uptake in the C-A-S-H gel. Therefore, sodium hydroxide modified the composition of hydrates in the LCM to a certain extent during the hydration process.

Influence of sodium hydroxide in enhancing the surface plasmon resonance of silver nanoparticles

Herein, we report green synthesis of silver nanoparticles, by confluence graph described previously using acetate as the stabilizer as well as a reducing agent. The process involves use of ‘green’ chemicals and benign synthesis conditions. The synthesized nanoparticles were tuned for their surface plasmon resonance by sodium hydroxide addition and scanned between 400 to 800 nm to study the hyperchromic effect. As the concentration of sodium hydroxide increased, the surface plasmon resonance of the silver nanoparticles at 420 nm increased (hyperchromic effect). The synthesized silver nanoparticles were further characterized by TEM, for morphology analysis and laser scattering for the electromagnetic properties of nanoparticles. Our method may provide a gateway for intensive exploration of innovative approaches in synthesizing silver nanoparticles and tuning (hyperchromic effect) their localized surface plasmon resonance by using sodium hydroxide, which has tremendous utility in diverse application sectors.

Effect of Sodium Hydroxide Concentrations on Properties of &lt;i&gt;Panicum repens&lt;/i&gt; for Pulp and Paper

Panicum repens is a species of grass known by many common names, including torpedo grass, creeping panic, panic rampant, couch panicum, wainaku grass, quack grass, dog-tooth grass, and bullet grass. The paper has been made from non-wood materials for long times. This research was used Panicum repens for made grass pulp as non-wood fiber. The influence of sodium hydroxide (NaOH) concentrations on properties of pulp from Panicum repens was investigated under room temperature. NaOH concentration levels were varied at 0%, 5%, 10%, 15%, and 20%, respectively. Moreover, Paper pulp from Panicum repens was observed by scanning electron microscope (SEM). This research has controlled the length of fiber approximately 0.5-2.5 cm before soaked with NaOH concentration at 1 hour and soak with water for controlled pH value at 7-8. Paper pulp was formed on a sieve. The result showed that color of paper pulp made from Panicum repens was light brown and green. SEM showed that NaOH concentration affects the physical properties of paper pulp. Moreover, true density of paper pulp was also investigated in this research.

Hydration and Properties of Slag Cement Activated by Alkali and Sulfate

AbstractIn this paper, the results of a study on the influence of sodium hydroxide, calcium hydroxide, aluminum hydroxide, sodium sulfate, calcium sulfate, and calcium sulfate dihydrate as activato...

The study of inhibiting structural material corrosion in water recycling systems by sodium hydroxide

Influence of sodium hydroxide on the rate and nature of corrosion of St3 carbon steel and SCh 18–36 grey cast iron in highly mineralized recycling water was studied. The nature of the corrosion damage was determined and the weight index of corrosion of these alloys was calculated. By means of polarization measurements, the electrochemical indices of anodic processes on steel and cast iron were determined. The effect of the circulating water pH on behavior of steel and cast iron under anodic polarization has been studied by cyclic voltammetry. It has been shown that the effective impact of pH on characteristics of the anode processes occured at pH≥11.4. At these pH values, the metal steady-state potential shifted to a region of positive values which was an indication of inhibition of the anodic process itself. At pH≥11.4, the pitting potential significantly shifted to the positive side: the process of healing pits was faster than their formation. It has been established that steel and especially cast iron tend to pass into a passive state at pH>10. The corrosion rate values did not exceed this index for the studied alloys in distilled water and were in the range of acceptable values. Thus, it is possible to effectively inhibit the rate of steel and cast iron corrosion, especially in the waterline zone by shifting the pH of the circulating water to the alkaline region. As a result of the conducted studies, optimal working conditions for iron alloys as the most technically important structural materials for designing closed cycles of circulating water supply systems have been established.

Influence of Sodium Hydroxide on the Austenitic 330Cb Alloy Oxidation at High Temperature

Sodium hydroxide is found on metallic conveyor belts as residue of the degreasing process of metallic screws put inside heat treatment furnaces at 900 °C. The 330Cb (Fe-34Ni-23Cr-1Nb-1.55Si) alloy is used to build these conveyor belts. With time, the amount of sodium hydroxide increases on the 330Cb steel surface. The aim of this work is to show the influence of the NaOH amount on the 330Cb oxidation during 48 h, at 900 °C. Results show that, on this austenitic steel, a protective silica scale formation is promoted by low oxygen containing gaseous environments and the high alloy silicon content. With low NaOH deposits the oxide layer is adherent and a SiO 2 cristobalite subscale is formed. It is also demonstrated that sodium combines with niobium to form NaNbO 3. When the NaOH amount exceeds 0.265 mg.cm-2 on the alloy surface, severe oxidation is observed leading to a fast growing FeCr 2 O 4 oxide scale.

The Effect of Sodium Hydroxide Molarity and Other Parameters on Water Absorption of Geopolymer Mortars

Objective: Durability one of the critical role effect in geopolymer serviceability. The capability of water to penetrate the mortar microstructure is mainly used to measure the durability, which also called permeability. Methods/Statistical Analysis: The influence of sodium hydroxide (NaOH) molarity, alkali Solution to Binder ratio (S:B), binder to aggregate ratio (B:A) and sodium silicate to sodium hydroxide ratio (NS:NH) on water absorption of Geopolymer Mortar (GPMs) are investigated in this article. Geopolymer mortar specimens of different NaOH molarity, S:B, B:A, and NS:NH were prepared and cured at different temperatures, 27°C and 60°C. Granulated blast furnace slag, fly ash, waste ceramic and waste glass bottle were used as a binder and mixed with river sand as fine aggregate. Findings: The results of experimental indicated that water absorption significantly affected of curing temperatures. The lower water absorption results were observed of the samples cured at ambient temperature (27°C) compared to samples cured at oven temperature (60°C). Applications/Improvements: The geopolymer specimens’ water absorption observed positively enhanced with increase concentration of alkaline solution.

Kinetic description of the hydrogenation of nitrobenzene and nitrosobenzene on skeletal nickel in aqueous solutions of propan-2-ol of different compositions

The kinetics of the hydrogenation of nitrosobenzene and nitrobenzene is simulated taking into account accompanying processes and specific features of the conversion of reactive groups. The constants of the hypothetical reaction steps are calculated. The influence of sodium hydroxide and acetic acid on the kinetic parameters of the reactions is discussed.

Influence of Sodium Hydroxide on the Properties of FGD Gypsum-Slag Composite Materials

By examining the compressive and flexural strength of composite and using scanning electron microscopy (SEM), we analyzed the influence of sodium hydroxide on the properties of FGD gypsum and slag composite materials and discussed the influence of sodium hydroxide on the setting time and mechanical strength of the composite materials and presented the action mechanism of sodium hydroxide as a stimulator. The results show that when the content of sodium hydroxide was percent of 0.25, the maximal strength of FGD gypsum-slag composite materials was reached.