Different Concentrations Of Alkali Research Articles

Bioactive surface modification of Ti–Nb alloy by alkaline treatment in potassium hydroxide solution

Abstract The aim of this work is to compare the responsive behaviour of titanium, niobium and titanium–niobium alloy during alkaline treatment in forming alkaline titanate layer and their resultant bioactive properties. Titanium and niobium powder mixture with composition in the beta region was pressed at 550 MPa and sintered at 1,200 °C for 2 h. The alloy was soaked in potassium hydroxide aqueous solution at 60 °C for 24 h with different concentrations of 0.5 M and 5 M. The effect of post sintering-heat treatment was investigated by annealing the treated alloy at 600 °C for 2 h. X-ray diffraction analysis and Fourier transform infrared spectroscopy analysis were used to evaluate the chemical composition and the functional group of material on the treated alloy surface respectively. Immersion in Hanks solution for 1 day resulted in traces of calcium and phosphate on alloy surfaces treated in different concentrations of alkali as well as post-heat treatment. The cell viability evaluation using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay on the new beta-Ti alloy with potassium-based titanate layer demonstrated potassium hydroxide treatment with a 5 M concentration after post-heat treatment significantly improved cell proliferation, which is a prerequisite for bone mineral apatite deposition.

Alkaline hydrogen peroxide pretreatment of bamboo residues and its influence on physiochemical properties and enzymatic digestibility for bioethanol production

Bamboo is a perennial rapid-growing plant that is given preference for renewable biosources for biofuels and bio-based chemical conversion. Bamboos are rich in cellulose and have highly recalcitrant biomass due to high lignin. Bamboo is abundantly available in Northeastern India and can be utilized as a feedstock biofuels. Here, we evaluated the pretreatment of bamboo residues Dendrocalamus strictus with different concentrations of alkali, hydrogen peroxide, and alkaline hydrogen peroxide and its influence on biomass digestibility for enhancement of sugar recovery with Celic C cellulase enzyme blend. Enzymatic hydrolysis data indicated untreated raw biomass showed a digestibility of 40% after 48 h of incubation. The biomass pretreated with alkali showed a maximum digestibility of 61% obtained from 10% loaded with 0.5% w/v NaOH. Pretreatment of the bamboo with H2O2 shows a maximum digestibility of 75% from biomass loaded with 1% w/v of H2O2. Combinational pretreatment of alkaline hydrogen peroxide showed a maximum efficiency of biomass digestibility of 83% attained from biomass loaded with 1% w/v NaOH-H2O2. Crystallinity index (CrI) analysis showed that CrI increased from 64% to 70.75% in pretreated biomass. FTIR and SEM analysis show changes in functional groups, morphology, and surface of biomass in pretreated biomass. Compositional analysis shows that 68% of lignin removal is obtained from alkaline hydrogen peroxide pretreatment. Cellulose content increased from 52% to 65%, and hemicellulose decreased from 18.6% to 8.6%. Results indicated that the potential possibility of bamboo waste biomass as feedstock for biorefinery products and alkaline hydrogen peroxide pretreatment methods is an efficient strategy for sugar recovery for bioethanol production.

Effects of microplastics on seed germination and seedling physiological characteristics of Spinacia oleracea under alkali stress.

Microplastics, a type of new environmental pollutant, have received much attention for their negative effects on organisms and environment. We examined the effects of microplastics on seed germination and seedling physiological characteristics of spinach (Spinacia oleracea) under alkali stress, taking polystyrene microspheres with a diameter of 100 nm (200, 400, 800, 1600 mg·L-1) as the microplastic treatment, and mixed NaHCO3 and Na2CO3 as alkaline salt solution (5, 10, 20, 40 mmol·L-1) according to the molar ratio of 1:1. The results showed that the presence of MPs (≥400 mg·L-1) inhibited seed germination, and that the length of roots and shoots increased at low while decreased at high concentration of MPs. Different concentrations of alkali alone could inhibit seed germination, root and bud elongation. With the increases of MPs concentration, SOD activity of spinach seedlings gradually decreased, while POD activity firstly increased and then decreased, and chlorophyll content increased at low concentration (200 mg·L-1) and decreased significantly at medium and high concentration (≥400 mg·L-1). Different alkali stresses reduced chlorophyll content of spinach seedlings, and the effects on SOD and POD were 'promotion at low concentration and inhibition at high'. In the treatments of microplastics (200, 800 mg·L-1) and alkali (5, 20 mmol·L-1) combined exposure, germination of spinach seeds was inhibited, and chlorophyll content decreased. The activities of SOD and POD in spinach seedlings were reduced under the combined exposure except the treatment of 200 mg·L-1 MPs and 5 mmol·L-1 alkali. Compared to the alkali stress, the combination of low concentration of MPs (200 mg·L-1) and alkali could improve germination rate, germination index, germination vigor and vigor index of seeds, and significantly promoted the elongation of roots and shoots, while the addition of high concentration of MPs (800 mg·L-1) reduced the germination rate, germination index, germination vigor and vigor index of seeds and inhibited the growth of roots and buds. The different concentrations of combined exposure inhibited the activities of SOD and POD and decreased the content of chlorophyll in spinach seedlings.

The effect of mercerization on water conductivity in cotton fabrics and its regulation

AbstractMercerization had been widely used in the textile industry because of its simplicity and ability to improve the luster, strength, and dyeing properties of cotton fabrics. However, the water transfer behavior of mercerized cotton fabrics had not been systematically investigated. In this work, cotton fabrics were treated with different concentrations of alkali (130 and 260 g/L) for structural characterization (scanning electron microscopy [SEM], Fourier transform infrared [FTIR]), water absorption (vertical wicking height), moisture absorption (moisture return rate), water retention, and so forth, and were compared with industrial mercerized cotton. It meant that water absorbency and water holding capacity of mercerized cotton textiles were improved by reducing surface impurity, increasing amorphous region, and increasing the number of free hydroxyl groups. It was easier for water molecules to move through the fabric as the vertical wicking height increased. Research showed that the water absorption and water transfer properties of cotton fabrics were related to the alkali concentration in the mercerized treatment, and a comparison with industrial mercerized cotton also proved this point. It also showed that the amount of tension had an effect on water transfer in the fabric, which provided further precision in regulating the mercerization process, improving the thermal comfort of mercerized fabrics, and achieving the aim of regulating the mercerization process according to market demand and environmental influences.

A technique for high-density wood softening in the micro-sectioning process for wood anatomy studies

Summary Wood identification for commercial applications is important and has a significant demand worldwide. Microscopic wood identification involves many processes such as softening, sectioning, and data analysis. Softening of wood is a crucial method for obtaining good sections for microscopic analysis but softening high-density wood is difficult. An alternate method of softening high-density wood for wood identification is presented. Different concentrations of alkali, NaOH, were tried, and optimized for different treatment times to obtain adequate softening of high-density wood. 20% NaOH treatment for 5 days at 30°C was used to soften high-density wood of variable density between 1 and 1.118 g/cm3. The species studied were Calophyllum spp., Shorea robusta, and Handroanthus spp., in which softening was satisfactory.

Tailor-made starch-based adhesives chemically modified with NaOH:urea and their applications on a cellulosic substrate

Adhesives formulated with native starches have high viscosity, low solids content, poor bond strength and stability due to the starch retrogradation. To overcome this problem, a strategy is the starch treatment with NaOH solution combined with urea, capable of intercalating in the polymeric chains of starch. The aims of this work were to develop adhesives based on chemically modified cassava starch with different NaOH:urea ratios and to study in depth the effect induced by the addition of different concentrations of alkali and urea in the adhesive capacity of formulations that determine their subsequent application in paper-based packaging.Firmness and consistency of the adhesive increased for the 1:1 ratio while it decreased for the NaOH:urea 2:1 ratio, suggesting that the hydrolysis of polymer chains occurred. Additionally, adhesives prepared with 15 % starch maintaining NaOH:urea ratios of 0.5:1: and 1:1 exhibited the highest stress values. ATR-FTIR studies supported the results obtained.It was possible to obtain formulations with different adhesive properties with applications in paper-based packaging. From the analysis of the studied parameters, the combination of 15 % w/w cassava starch with a ratio of NaOH:urea 1:1 allows obtaining adhesives with adequate consistency and adhesive capacity which remain stable during the adhesive storage.

Changes in the structure of polysaccharides under different extraction methods

Changes in the structure of polysaccharides under different extraction methods

Extraction of cellulose from paulownia plants and its simple ester carboxymethyl cellulose (na-kms) technology

In this experiment, Paulownia fiber plant is ground to 0.5-1 cm. In order to determine the optimum alkali solution concentration to extract cellulose from the raw material, the optimum degree of polymerization was determined by boiling in 25, 35, 50, 55 g/l solution. It can be seen from the table that certain properties of cellulose produced under the influence of different concentrations of alkali have different indicators. At alkaline concentration of 50 g/l, the cellulose yield was 49.6%, α-cellulose 89.5%, and the degree of polymerization was known in 1100 experiments. Ash content was a positive indicator of 1.78%. The scientific essence is that the cellulose is first soaked in isopropyl alcohol and mercerized in caustic alkali (NaOH) solution. Then, the alkylation process is carried out by adding a certain amount of monochloroacetic acid to the alkaline cellulose. Then, the alkylation process is carried out by adding a certain amount of monochloroacetic acid to the alkaline cellulose. The resulting carboxymethylcellulose is sent for purification. Na-CMC with 38-40% moisture content is washed in 53% ethyl alcohol and dried.

Triaxial test and microstructure analysis of soil from alkali contaminated sites

The protection of site cultural relics is facing great challenges of site soil instability and contamination. Targeting at the special geological environment of Kaifeng region, the affecting laws of different concentrations of alkali on mechanical properties of site soil in this region are studied in this paper. The triaxial test is conducted to study the mechanical properties of site soil, including its failure pattern, stress-strain relationship, stress path and strength index, etc. The X-ray diffraction test and scanning electron microscope test are used to analyze the composition, particle state, and pore characteristics of the soil before and after contamination, and to evaluate the stability of the site soil. At the site combining with microstructure changes and macro mechanical properties. The results show that, from the macroscopic surface, with the increase of alkali concentration, the failure shear plane usually appears along the 45° direction. From the perspective of mechanical properties, the stress-strain relationship of the site soil is caused by the strengthening of soil deformation, and the alkali concentration increases, and the curve gradually develops from hardening type to softening type. The stress path is the line connecting the points in the sequence of the stress change process, which is different, and the corresponding soil deformation and strength characteristics will also appear very different. The stress path of soil with different alkali concentration is different. Under the same σ3 condition, the stress σ1 is different. The stress change is expressed in macroscopic terms as different forms of soil damage. Under 0 % concentration, the strength index of soil is 82.14 kPa, 21.67°, and the alkali concentration is 4–16 %, the internal friction Angle is gradually increased, and the cohesion is slightly reduced. From the micro perspective, the main components of the contaminated site soil are SiO2, Al2O3, CaO and Fe2O3. In the process of alkali-soil reaction, alkali reacts with oxides in soil to form Na2AlO2, which has a certain cementation effect. SiO2 reacts with NaOH solution to generate Na2SiO3, which has strong cohesiveness and strength. The newly generated cementing material in the soil increases, and the bonding force between particles increases. In addition, some cements fill the inner pores and improve the shear strength of soil. Under the same pressure, the stress-strain curve of soil gradually developed from hardening type to softening type with the increase of alkali concentration. In the stress-strain curve of soil, with the increase of alkali concentration, the soil reaches the strength at failure under small deformation. The increase of alkali concentration reduces the plasticity and increases the brittleness of soil. At this time, if the stress is localized, shear bands will appear and the stability of soil will decrease. The study of soil properties changes caused by different alkali pollution concentrations can provide a scientific basis for the reinforcement and protection of soil sites or ancient cultural foundations in Kaifeng area.

Morphological characteristics of starch sol-gel and its influences on flocculation of fine particles

Pasting starch into sol-gels by alkali is one of the most common methods for its use as flocculants in flotation. Any variation in its gelatinization process, however, could lead to different starch solutions with certain charges, sizes, and configurations of the segments, influencing their flocculating properties onto mineral surfaces. The purpose of this study is to identify the morphological characteristics of the starch sol–gel digested with different concentrations of alkali and their flocculation mechanisms on hematite through a series of tests, such as viscosity, turbidity, adsorption, pasting titration, settling, zeta potential All results pointed out that the gel-sol transition of starch was possibly governed by alkali concentrations or starch to alkali weight ratios. As the sodium hydroxide concentration increases, an increase in viscosity but a decrease in turbidity of the starch solution was obtained, inducing an upwards trend in the settling rates of the particle flocs. A suitable sol–gel by 1.25% sodium hydroxide (a 1.6 wt ratio of starch to NaOH) at turbidity of near 2 NTU and a viscosity of 258 mL/g harvested a maximum adsorption density of 11.5 mg/g hematite at a settling rate of 7.1 × 10−5 m/s. A certain amount of acidic contents on the segment chains resulting from alkali gelatinization play an important role in determining the morphological characteristics of the starch sol–gel at different pH values affecting adsorption density on iron oxides. It is worthy to be noted that the starch remnants at very small sizes produced by high concentrations of NaOH by over 1.50% or at a starch to alkali weight ratio of less than 1.3 were hard to achieve high efficiency on flocculating the particles but occasionally dispersing them instead. It could attribute to the less possibility of “bridging interactions” between the particles and these small segments with negative charges, which may limit the size and compactness of the particle flocs, and, consequently, reduce their settling rates.

Laboratory Study of High-Resistance Laterite-Based Geopolymer Bricks

A high amount of energy is required to produce different types of clay and sand-lime bricks, and a huge amount of carbon dioxide is released into the atmosphere. Also, brick waste from the destruction of dilapidated buildings pollutes the environment. Application of pozzolanic sources containing aluminosilicate and alkaline activators can be beneficial in production of geopolymer bricks, which do not need to be baked in a furnace and can be recycled. A laterite-based geopolymer brick mix design was introduced in this study as an environmental-friendly material. This type of brick is produced using available and cheap raw materials without the need for high furnace heat. The raw materials included laterite soil as aluminosilicate, laterite aggregate filler passed through sieve No. 8 and an alkaline activating solution with different concentrations. The effect of laterite aggregate size on the compressive strength of these brick samples was investigated. The results showed that the compressive strength of the prepared bricks here was much higher than the recommended standards for construction bricks and was similar to those of high-resistance bricks. The size of laterite aggregate had a significant effect on the compressive strength of geopolymer brick samples. The percentage of water absorption of the bricks with different concentrations of alkali activating solution was also within the recommended range for construction bricks.

Preparation of Halloysite/Ag2O Nanomaterials and Their Performance for Iodide Adsorption

Halloysite/Ag2O (Hal/Ag2O) nanomaterials were prepared by growing Ag2O nanoparticles on the surface of nanotubular halloysite using silver nitrate solution under alkaline conditions. The nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption. Good dispersion of Ag2O nanoparticles with average sizes of 6.07 ± 2.5 nm and 8.04 ± 3.8 nm was achieved in the nanomaterials when using different concentrations of alkali. The nanomaterial with 6.36% Ag2O (Hal/Ag2O-2) exhibited rapid adsorption to iodide (I−); adsorption equilibrium can be reached within 100 min. The adsorption capacity of I− on Hal/Ag2O-2 is 57.5 mg/g, which is more than 143 times higher than that of halloysite. The nanomaterial also showed a better adsorption capacity per unit mass of Ag2O due to the better dispersion and less coaggregation of Ag2O in the nanomaterial than in the pure Ag2O nanoparticles. Importantly, Hal/Ag2O-2 exhibited high selectivity for I−, and its I− removal efficiency was hardly affected by the coexistence of Cl−, Br−, or SO42−, as well as the initial pH of the solution. With an excellent adsorption performance, the prepared Hal/Ag2O nanomaterial could be a new and efficient adsorbent capable of the adsorption of radioactive I− from aqueous solution.

Multistep Structural and Chemical Evaluation of Sugarcane Baggase, Pretreated With Alkali for Enhancing the Enzymatic Saccharification by Cellulase and Xylanase of the Pseudomonas sp. CVB-10 (MK443365) and Bacillus paramycoides T4 (MN370035) Mix-Culture System

The enzymatic saccharification of sugarcane bagasse was significantly increased by alkali pretreatment under mild conditions. The effectiveness of different concentrations of alkali and acid pretreatment of sugarcane bagasse for improving the enzymatic saccharification of lignocellulose has been evaluated. The sugarcane bagasse was characterized to contain 39.52% celluloses, 25.63% hemicelluloses, and 30.36% lignin. After that, sugarcane bagasse was pretreated with 5 and 10% of H2SO4 and NaOH at 121°C for 60 min. FTIR, XRD, and SEM analyses also showed significant molecular and surface structure changes of the sugarcane bagasse with 10% NaOH. Maximum saccharification was 489.5 mg/g from 10% NaOH pretreatment followed by 322.75, 301.25, and 276.6 mg/g from 10% H2SO4, 5% NaOH, and 5% H2SO4, respectively, which were 55.1, 32.0, 27.1, and 20.6 times higher than the that of the control. Cellulase and xylanase produced by Pseudomonas sp. CVB-10 (MK443365) and Bacillus paramycoides T4 (MN370035) were used to hydrolyze the pretreated bagasse, and the optimal condition was determined to be 30 h of the enzymatic reaction with the 3:1 ratio of enzymes under the temperature of 55°C, pH 5.0, and substrate concentration of 3%, leading to celluloses and hemicelluloses conversion in the enzymatic hydrolysis/saccharification that is more proficient.

Laboratory Study of High-Resistance Laterite-Based Geopolymer Bricks

A high amount of energy is required to produce different types of clay and sand-lime bricks, and a huge amount of carbon dioxide is released into the atmosphere. Also, brick waste from the destruction of dilapidated buildings pollutes the environment. The application of pozzolanic sources containing aluminosilicate and alkaline activators can be beneficial in the production of Geopolymer bricks, which do not need to be baked in a furnace and can be recycled for industrial and port facilities. A laterite-based Geopolymer brick mix design was introduced in this study as an environmental-friendly material. This type of brick is produced using available and cheap raw materials without the need for high furnace heat. The raw materials included laterite soil as aluminosilicate, laterite aggregate filler passed through sieve no. 8, and an alkaline activating solution with different concentrations. The effect of sieve size for laterite soil screening on the compressive strength of these brick samples was investigated. The results showed that the compressive strength of the prepared bricks here was much higher than the recommended standards for construction bricks and was similar to those of high- resistance bricks. The size of laterite soil sieves had a significant effect on the compressive strength of Geopolymer brick samples. The percentage of water absorption of the bricks with different concentrations of alkali activating solution was also within the recommended range for construction bricks

Biodegradable green composite film developed from Moringa Oleifera (Sahajana) seed filler and PVA: Surface functionalization, characterization and barrier properties

The present work focuses on surface functionalization, characterization, biodegradability and barrier properties of MOSF as a practicable reinforcement in PVA matrix. Film-forming dispersions at different concentrations of alkali and acid treatments were casted at room temperature. The effect of surface modifications on the developed film’s compositional, physical, mechanical, biodegradability and barrier properties were analyzed. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) were used to describe the functional composition, formation and surface morphology of the film. The 5% acid treated film significantly increases the tensile strength (33.69 MPa) and flexural strength (56.612 MPa), which was close to the frequently used LDPE and HDPE package films. Composite films were moisture absorptive but simultaneously capable to maintain uniformity and composition upon modifications. Lower water vapor permeability (1.42 × 10−10gs−1 m−1 Pa−1), eminent biodegradability proved the suitability of composite film for various packaging applications.

Analysis of Water Absorption of Different Natural Fibers

The demand for natural fibers has always been high due to their unique characteristics like strength, lightweight, availability, bio-degradability, etc. In every phase of life, from clothing to technical textiles, natural fibers are used. Water absorption of fibers is considered really important in many aspects, e.g., Sportech, Medtech, Geotech, etc. This work analyses water absorption of raw and alkali-treated cotton, arecas, pineapple leaves, and banana fibers. Fibers were scoured with different concentrations of alkali (2, 4, 6 gm/L NaOH), washed and neutralized with the dilute acetic acid solution, then dried. Later on, the fiber samples were immersed into distilled water, and water absorption percentages of the fibers were determined every 10 minutes within 1 hour in total. It appeared that at untreated conditions, the areca fiber has the highest water absorption capacity compared to the other fibers. Alkali-treated cotton shows the highest water absorption, and areca fibers show approximately 60% water absorption of cotton.

Synthesis of hierarchical GaZSM-5 zeolites by a post-treatment method and their catalytic conversion of methanol to olefins

Abstract A number of hierarchical GaZSM-5 zeolite molecular sieves with diverse amounts of mesoporosity and acidity were prepared by post-synthetic desilication with different concentrations of alkali. The zeolite structure and acidity have an important effect on the catalyst lifetime and the product distribution of the methanol to olefins (MTO) reaction, which have been investigated. The changes in pores and acidity by post-treatment were characterized by XRD, SEM, TEM, NH3-TPD, FTIR, Py-IR, etc. An alkali treatment of an appropriate concentration can increase the mesoporosity and reduce the strong acid density, which improves catalytic stability by suppressing coke formation. However, excessive alkali concentrations cause low crystallinity and excessive acidity despite a high mesoporosity, which is conducive to the formation of aromatic products and coking. The desilication significantly changes acidity of GaZSM-5 zeolites and affects the product selectivity; the selectivities of C2 and C3 olefin are consistent with the change of Lewis acid amount.

Compendious Characterization of Chemically Treated Natural Fiber from Pineapple Leaves for Reinforcement in Polymer Composites

ABSTRACT Nowadays, the research is more focused on natural fibers because of their comparable properties of biodegradability, environment friendly, ease of access, lightweight, and low cost. In this research paper, the effect of chemical treatment on morphological, physical, chemical, mechanical, and thermal properties of pineapple leaf fibers has been studied. Because of the highest amount of cellulosic content, this fiber is having great potential for mechanical and thermal strength. Initially, fibers were extracted using retting and scrapping method and thereafter treatment with different concentrations of alkali was performed. Characterization has been done to analyze its properties and found that the alkaline treatment leads to better mechanical and thermal properties but only up to 7% alkali concentration. After increasing the concentration above 7%, the properties start degrading because of the onset of fiber degradation at higher alkali application. Mercerization helps in making fiber more compatible with hydrophobic matrix resin and hence can be easily reinforced with polymeric matrix for specific composite applications.

Experimental study of alkaline-surfactant-polymer compositions for ASP-flooding of cores from highly viscous oil reservoirs

The paper presents experiments on using alkali–surfactant–polymer compositions (for ASP flooding) in tests on cores saturated with highly viscous oil. The phase behavior was evaluated for solutions with different concentrations of alkali (NaOH) and surfactant (SDS) after mixing with highly viscous oil samples; this defined the optimal agent com-positions for producing Winsor type III emulsions. Experiments on core saturated with highly viscous oil demonstrated the pumping of ASP agent in the form of aquatic solutions surfactant/alkali and polymer after regular water flooding give the gain in the oil displacement in the range from 19 to 37 %.

Water Absorption Characteristics of Successive Alkali Treated Jute/Polylactic Acid Composites

Hydrolytic degradation of polylactic acid composites incorporated with untreated (UTJ/PLA) and successive alkali treated short jute fiber at different concentrations of alkali (5STJ/PLA, 10STJ/PLA and 15STJ/PLA) with varying fiber weight fractions due to water absorptions were investigated at 23°C. The results revealed that the steadiness of UTJ/PLA and STJ/PLA composites in water depend less on jute fiber content and it is significantly influenced by fiber treatment. The water uptake of plain PLA after 30days was 0.97%, evidencing the hydrophobicity of neat PLA. From the results, it is depicted that the water uptake quantity rised in all types of composites with increase in the jute fiber fraction. The maximum water uptake of 10.82% was seen after 30days for composite with 25% of raw jute fiber. Further, the percentage of water absorption reduces in the composite with increasing NaOH percentage for treating the jute fibers. The amount of water absorption is 6.59, 5.73, and 4.60% for composites with 25% of treated fiber with 5%, 10%, and 15% of sodium hydroxide concentration followed by bleaching with H2O2, respectively. The Fickian behavior is observed in plain PLA and its composite with untreated and alkali treated jute fiber at 5 and 10% concentrations of NaOH in the treatment. But in case of PLA composite with successive alkali treated fiber at 15% NaOH concentration, there is a deviation in the Fickian behavior because higher concentrations of alkali in the treatment may lead oxidative damage to the fiber.