Addition Of NaOH Research Articles

Hydrothermally assisted Cr@Zn bimetal sulfide nanoparticles with varying calcination temperature as battery grade material for supercapattery

A newly introduced hybrid device, supercapattery has captured the attention of researchers worldwide for its potential to achieve high energy and power density. The performance of this supercapattery depends highly on the materials of the electrodes. Recent research processes: using single transition metal sulfides as electrode materials for their specific capacity and rapid charge transfer processes; however, it suffers from poor electrical conductivity. Therefore, in this work, a novel bimetal Chromium Zinc Sulfide (Cr@ZnS) was synthesized to improve the conductivity via creation of synergistic effect between Cr and Zn ions. During the preparation method, different reducing agents (KOH and NaOH) were used to study the effect of the reducing agents on the electrochemical performance of Cr@ZnS. It was perceived that addition of KOH exhibits better charge storage capacity compared to addition of NaOH as they influence the production of S2- ions during the Cr@ZnS formation. The produced Cr@ZnS was then subjected under different calcination temperatures (100 °C, 200 °C and 300 °C) to investigate its effect on Cr@ZnS performance. From this work, it was revealed that calcination deteriorates the electrochemical performance of Cr@ZnS due to occurrence of morphological evolution in Cr@ZnS. The maximum specific capacitance achieved by Cr@ZnS electrode is 1338.85F g−1 at 3Ag−1. When the optimized Cr@ZnS electrode was coupled with AC, the device exhibited excellent energy and power density value of 29.15 Wh kg−1 and 18.85 kW kg−1, respectively with a decent capacity retention of 82 % over 10,000 cycles.

Numerical simulation study of the mechanism of hydrogen explosion inhibition by fine water mist containing NaOH

The effect of NaOH-containing fine water mist on hydrogen explosion flames is investigated utilizing numerical simulations using a multi-step model of the chemical reaction mechanism. The suppression effect of hydrogen explosion fine water mist in different pipes is studied. The chemical agent NaOH is introduced into the water mist, and the inhibition mechanism is studied from a microscopic perspective. The results show that the addition of fine water mist can effectively reduce the flame temperature and that the fine water mist completely evaporates and absorbs heat in the preheating zone. The addition of NaOH can improve the inhibition effect of ultra-fine water mist on hydrogen explosion, which is the result of the joint action of physical inhibition and chemical inhibition. The mole fraction curve shows that NaOH delays the reaction process of hydrogen explosion by trapping high-energy free radicals.

Ammonia stripping and scrubbing followed by nitrification and denitrification saves costs for manure treatment based on a calibrated model approach

Resource-efficient nitrogen management is of high environmental and economic interest, and manure represents the major nutrient flow in livestock-intensive regions. Ammonia stripping/scrubbing (SS) is an appealing nitrogen recovery route from manure, yet its real-life implementation has been limited thus far. In nutrient surplus regions like Flanders, treatment of the liquid fraction (LF) of (co–)digested manure typically consists of nitrification/denitrification (NDN) removing most N as nitrogen gas. Integrating SS before NDN in existing plants would expand treatment capacity and recover N while maintaining low N effluent values, yet cost estimations of this novel approach after process optimisation are not yet available. A programming model was developed and calibrated to minimise the treatment costs of this approach and find the balance between N recovery versus N removal. Four crucial operational parameters (CO2 stripping time, NH3 stripping time, temperature and NaOH addition) were optimised for 18 scenarios which were different in terms of technical set-up, influent characteristics and scrubber acid. The model shows that SS before NDN can decrease the costs by 1 to 56% under optimal conditions compared to treatment with NDN only, with 1 to 8% reduction for the LF of manure (22–29% recovered of N treated), and 11 to 56% reduction for the LF of co-digested manure (42–67% recovered of N treated), primarily dependent on resource pricing. This study shows the power of modelling for minimum-cost design and operation of manure treatment yielding savings while producing useful N recovery products with SS followed by NDN.

Enhancing biogas production from cheese whey using Zero-Valent Iron: A comparative analysis of batch and semi-continuous operation modes

Cheese whey (CW) is the primary by-product of dairy industries, and its anaerobic treatment presents several challenges. Among these is the production of high levels of volatile fatty acids (VFAs) due to rapid biodegradation, which leads to a drop in pH and adversely impacts methanogenesis. This study aims to evaluate the impact of Zero-Valent Iron (ZVI) on the anaerobic digestion of CW under both semi-continuous and batch conditions. Since ZVI generates H2 and increases pH under soluble CO2 conditions, the study also focuses on the effects of ZVI on solubilization/hydrolysis, acidification, and microbial response. Three anaerobic bioreactors (R25-PZVI with 25 g/L powder ZVI, R50-SZVI with 50 g/L scrap ZVI, and R-Control without ZVI), at semi-continuous mode, treated cheese whey at varying organic loading rates. After 118 days, R25-PZVI showed the highest CH4 yield and best COD removal, followed by R50-SZVI. Despite NaOH additions, it maintained a lower VFA/ALK ratio than the control. Under semi-continuous mode, CH4 composition in R25-PZVI was 59%, rising to over 95% under batch conditions due to the higher pressure and subsequent solubilization of H2 and CO2. The ZVI mainly impacted methanogenesis and acidogenesis and not solubilization/hydrolysis. 25-PZVI's superior performance was due to its increased H2 generation and alkalinity over 50 g/L SZVI, as was found in the abiotic test. Under semi-continuous conditions, Methanobacterium (a hydrogenotrophic methanogen) and Methanosarcina were the dominant genera in the R25-PZVI reactor. Under batch conditions, Methanothrix displayed a higher abundance, which explained the increased acetic acid utilization.

Process intensification in the ketalization of glycerol with acetone catalyzed by NaHSO4-NaOH catalytic system

Glycerol is one cheap byproduct in production of biodiesel, and the ketalization of glycerol is one of the most important and effective way to increase its value and improve the sustainability of biodiesel. The ketalization of glycerol with acetone is always catalyzed by acid catalyst. In this work, NaOH was added into the reaction system during the ketalization process catalyzed by NaHSO4, and it was found for the first time that this process could be intensified by NaOH significantly. The acidity of acidic catalysts would affect their catalytic performance. Increasing reaction temperature and time, molar ratio of acetone to glycerol, the dosage of NaHSO4 and molar ratio of NaOH to NaHSO4 could favor for the ketalization, but the excessive formation of water and the evaporation of acetone would retard the reaction. The addition of NaOH could destroy the intermolecular hydrogen bond network of glycerol molecules, making the hydroxyl groups bared in free state, and increase the amount of electrophilic transition state of acetone, which help to promote the transformation of glycerol to solketal significantly. With the assistance of NaOH, the conversion rate of glycerol could even reach 97.58 % without extracting water continuously from the reaction system.

Dual-mode transfer response based on electrochemical and fluorescence signals for the detection of amyloid-beta oligomers (AβO).

An aptamer sensor has been developedutilizing a dual-mode and stimuli-responsive strategy for quantitative detection of AβO (amyloid-beta oligomers) through simultaneous electrochemical and fluorescence detection. To achieve this, we employed UIO-66-NH2 as a carrier container to load MB (Methylene Blue), and Fe3O4 MNPs (iron oxide magnetic nanoparticles) with aptamer (ssDNA-Fe3O4 MNPs) fixed on their surface for biological gating. The ssDNA-Fe3O4 MNPs were immobilized onto the surface of UIO-66-NH2 through hydrogen bonding between the aptamer and the -NH2 group on the surface of UIO-66-NH2, thereby encapsulating MB and forming ssDNA-Fe3O4@MB@UIO-66-NH2. During the detection of AβO, the aptamer selectively reacted with AβO to form the AβO-ssDNA-Fe3O4 complex, leading to its detachment from the surface of UIO-66-NH2. This detachment facilitated the release of MB, enabling its electrochemical detection. Simultaneously, the AβO-ssDNA-Fe3O4 complex was efficiently collected and separated using a magnet after leaving the container's surface. Furthermore, the addition of NaOH facilitated the disconnection of biotin modifications at the 3' end of the aptamer from the avidin modifications on the Fe3O4 MNPs. Consequently, the aptamer detached from the surface of Fe3O4 MNPs, resulting in the restoration of fluorescence intensity of FAM (fluorescein-5'-carboxamidite) modified at its 5' end for fluorescence detection. The dual-mode sensor exhibited significantly enhanced differential pulse voltammetry signals and fluorescence intensity compared to those in the absence of AβO. The sensor demonstrated a wide detection range of 10 fM to 10 μM, with a detection limit of 3.4 fM. It displayed excellent performance in detecting actual samples and holds promising prospects for early diagnosis of Alzheimer's disease.

Structure of 2-nitro-2’-hydroxy-5’-methylazobenzene: Theoretical and spectroscopic study

Objectives. 2-Hydroxy-nitroazobenzenes comprise reagents for the synthesis of heteroaromatic compounds, in the molecules of which the benzene and azole cycles are annulated. These reagents are widely used in the production of chemical products for various industries. In particular, 2-2’-hydroxy-5’-methylphenylbenzotriazole is used as an effective photo stabilizer for polystyrene and polyethylene. A promising method for its preparation is the liquid-phase catalytic hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene (2NAB). The aim of the present study was to establish the structure of 2NAB in solutions of different composition.Methods. Theoretical calculations were carried out within the framework of the density functional theory at a temperature of 298.15 K for the gas phase at B3LYP/6-311++G(d, p) and M06-2X/6-311++G(d, p) levels; for hexane, 2-propanol, toluene at B3LYP/6-311++G(d, p) level using the conductor-like polarizable continuum model. An experimental study to determine the probable isomeric structure of 2NAB in various solvents, including sodium hydroxide (NaOH) and acetic acid (CH3COOH) additives, was carried out using infrared (IR) and ultraviolet (UV) spectroscopy.Results. The most probable structure of 2NAB isomers for the gas phase and a number of solvents was determined. Experimental and theoretical IR and UV spectra were obtained. The thermodynamic characteristics of the reaction of intramolecular proton transfer from –OH to –N=N– group in the gas phase were calculated.Conclusions. A comparison of the experimental and calculated results supports the conclusion that the cis-isomer should be considered most probable for the gas phase. For the studied solutions, a trans-isomer of 2NAB with hydrogen bonds formed between the hydroxyl group hydrogen and the β-nitrogen atom of the azo group of dye molecule should be considered as the most likely structure. In the studied individual and binary solvents, prototropic equilibrium is shifted towards the azo form of the dye, while intramolecular proton transfer is possible only in aqueous diethylamine and dimethylformamide solutions with additions of NaOH.

Preparation of adsorptive TiO2/SiO2 core-shell nanospheres by ultrasonic-coupled alkali leaching process: Synergy of adsorption and photocatalysis towards 2,4-dinitrophenol removal

Spent selective catalytic reduction (SCR) catalysts comprise of abundant valuable TiO2. Therefore, recovery of TiO2 from spent SCR catalysts has highly economic benefits. In this study, an ultrasonic-coupled alkali leaching process was developed for environment-friendly preparation of adsorptive TiO2/SiO2 core-shell nanospheres from spent SCR catalysts. The results show that the synergy of ultrasonic and alkali leaching significantly enhances the separation of other ingredients from TiO2/SiO2, and the addition of NaOH, when compared with the traditional roasting-leaching process, decreases by 70%. The as-prepared adsorptive TiO2/SiO2 core-shell nanospheres exhibit superior adsorptive and photocatalytic performance for 2,4-dinitrophenol removal, and 99.9% of degradation rate was achieved within 120 min under the cooperation between adsorption and photocatalytic oxidation. This study provides a potential method for recycling of valuable adsorptive TiO2/SiO2 core-shell nanospheres from spent SCR catalysts.

Structure of 2-nitro-2’-hydroxy-5’-methylazobenzene: Theoretical and spectroscopic study

Objectives. 2-Hydroxy-nitroazobenzenes comprise reagents for the synthesis of heteroaromatic compounds, in the molecules of which the benzene and azole cycles are annulated. These reagents are widely used in the production of chemical products for various industries. In particular, 2-2’-hydroxy-5’-methylphenylbenzotriazole is used as an effective photo stabilizer for polystyrene and polyethylene. A promising method for its preparation is the liquid-phase catalytic hydrogenation of 2-nitro-2'-hydroxy-5'-methylazobenzene (2NAB). The aim of the present study was to establish the structure of 2NAB in solutions of different composition.Methods. Theoretical calculations were carried out within the framework of the density functional theory at a temperature of 298.15 K for the gas phase at B3LYP/6-311++G(d, p) and M06-2X/6-311++G(d, p) levels; for hexane, 2-propanol, toluene at B3LYP/6-311++G(d, p) level using the conductor-like polarizable continuum model. An experimental study to determine the probable isomeric structure of 2NAB in various solvents, including sodium hydroxide (NaOH) and acetic acid (CH3COOH) additives, was carried out using infrared (IR) and ultraviolet (UV) spectroscopy.Results. The most probable structure of 2NAB isomers for the gas phase and a number of solvents was determined. Experimental and theoretical IR and UV spectra were obtained. The thermodynamic characteristics of the reaction of intramolecular proton transfer from –OH to –N=N– group in the gas phase were calculated.Conclusions. A comparison of the experimental and calculated results supports the conclusion that the cis-isomer should be considered most probable for the gas phase. For the studied solutions, a trans-isomer of 2NAB with hydrogen bonds formed between the hydroxyl group hydrogen and the β-nitrogen atom of the azo group of dye molecule should be considered as the most likely structure. In the studied individual and binary solvents, prototropic equilibrium is shifted towards the azo form of the dye, while intramolecular proton transfer is possible only in aqueous diethylamine and dimethylformamide solutions with additions of NaOH.

Mechanistic investigation of using low salinity alkaline surfactant solutions in carbonate reservoirs based on polarity of crude oil

The chemical enhanced oil recovery (CEOR) process is introduced as one of the most effective methods for reducing the residual oil saturation through oil reservoirs. Because the chemical phase has a great potential for altering the reservoir rock and fluids properties. The main purpose of this study is a combination of low saline water (LSW) with surfactant and alkaline-surfactant to achieve maximum oil recovery by the combination of different mechanisms. In this work, the fluid–fluid and rock-fluid interactions were investigated by conducting several experimental techniques for two varied crude oil samples. Due to the high polarity of resin and asphaltene molecules, these two crude oil samples were divided into low-polar and high-polar samples. The optimum diluted seawater was used as LSW for both crude oil samples at 3000 ppm total dissolved solids. Based on obtained results from the interfacial tension (IFT) measurement tests and dynamic contact angle, using NaOH with LSW and AOS at critical micelle concentration (CMC) has a greater influence on reducing the IFT and altering the carbonate rock wettability from oil-wet to water-wet condition compared to Na2CO3. Adding only 100 ppm NaOH to the LSW-AOS(CMC) solution, the IFT values between an alkali-surfactant solution with low-polar and high polar crude samples were decreased from 0.43 and 1.33 mN/m to 0.21 and 0.55 mN/m, respectively. Moreover, the pH of LSW-AOS solution rises with the addition of NaOH to the solution and the surface charge moves toward a more negative charge based on the zeta potential results. This phenomenon increases the repulsion between surface charge and negatively charged polar components and, consequently desorption of polar components from the rock surface get improved. Furthermore, some in-situ surfactant (soap) generates by a reaction between NaOH and carboxylic acids and the creation of an ion pair between surfactants (AOS and Soap) and adsorbed polar groups which lead to the creation of a hybrid mechanism between LSW, AOS, and NaOH for changing the wettability from oil-wetness toward water-wetness. Therefore, the maximum oil recovery was achieved by flooding with LSW- AOS(1000 ppm)-NaOH (100 ppm) solution for both crude oil samples, high polar and low polar cured oil samples, that obtain 42.24 % and 71.67% recovery factors, respectively. Moreover, coreflooding results confirmed the micromodel results in the presence of initial water saturation at high temperature condition.

Identification of natural dyes with halochromic properties and their potential use as food spoilage indicators

Purpose The purpose of this research is to identify and investigate some natural dyes with halochromic properties for potential use as food spoilage indicators to reduce waste and curve the negative effects of food borne diseases. Design/methodology/approach Exactly 10 potential dye-yielding plants were selected based on their colour (mostly purple, red, maroon and pink). Solvent extraction was used to extract the dyes and pH differential method was used to determine the concentrations of anthocyanin in the extracted dyes. Different concentrations of hydrochloric acid and sodium hydroxide (0.1 M, 1 M and 2 M) in drops and in excess as acidic and basic solution, respectively, were used to test the halochromicity of the extracted dyes. Methyl red (a synthetic dye) was used as a reference standard/control. The pH of the dyes was recorded before and after addition of both NaOH and HCl solutions. Findings Five out of the 10 dyes extracted (labelled as dye A–E for Ti plant (green Cordyline fruticosa), coleus (Coleus blumei), paper flower (Bougainvillea glabra), painted nettle (Palisandra coleus) and purple heart (Setcresea purpurea), respectively, were found to be halochromic (even at low doses) by changing its colour when exposed to both acidic and basic solutions. While other dyes labelled F–J for red acalypha (Acalypha wilkesiana), golden shower (Cassia fistula), golden dew drop (Duranta repens), wild sage (Lantana camara var Aculeata) and pink oleander (Apocynaceae Nerium oleander), respectively, were either completely insensitive to the solutions in drops, slightly sensitive at high doses or the colour change is insignificant. Although some dyes were found to be more sensitive than others but in most cases, the colour changes in halochromic dyes were more stable in acidic conditions than in basic making it more sensitive to the basic than the acidic solution with the exception of dye A and E (to some extent) which was sensitive to both acidic and basic solution. The anthocyanin contents of dye A–J were found to be between the range of 2.28–10.35 mg/l with dye E having the lowest and dye J with the highest anthocyanin concentration, respectively. The initial pH of all the dyes falls within the range of 4.8–7.3 with most found within the acidic range. Originality/value Halochromic dye research studies are still at the infancy stage in developing world despite the vast available and abundant potential natural halochromic dye-yielding plants. The study explored this area of research and gives an opportunity for the development of smart packaging for pH-sensitive foods using natural dyes as an alternative to conventional synthetic dyes to reduce cost and also curve the negative effect of synthetic dyes as well as food borne diseases.

Development of bio-mechanical rice straw pulp by high consistency kneader with thermal and Alkaline

The purpose of this study was to develop a bio-mechanical pulp from rice straw with thermal and low chemical dosage. The process is carried out by thermal alkali kneading pretreatment (0–5% NaOH) with a high concentration kneader, enzyme pretreatment (0.2–4%) and Hollander beater. The results showed that the addition of NaOH was the main factor affecting the properties of pulp and paper, and the best properties of straw pulp could be obtained when NaOH and enzyme dosage were 5% and 0.2%, respectively. Although the optimum rice straw pulp is inferior to straw soda pulp in terms of tensile, burst and ring crush index, it is superior to old corrugated cardboard pulp and partially meets the CNS standards of corrugated medium paper and linerboard without the addition of chemicals. Therefore, the bio-mechanical rice straw pulp in this study has the potential to be produced as industrial paper.

Fresh and hardened state properties, reaction kinetics and microstructure of sodium sulfate/sodium hydroxide – Activated slag mixtures

This study investigated the impact of incorporating sodium hydroxide (NaOH) on the properties of ground granulated blast furnace slag (GGBFS) activated by sodium sulfate (Na2SO4). Specifically, the rheological properties, setting behavior, reaction kinetics, mechanical performance, and microstructure of the mixtures were examined. Results indicated that using only Na2SO4 as the activator resulted in mixtures with long setting times and no compressive strength at early ages. However, the addition of NaOH to the Na2SO4 activator significantly improved the reaction kinetics of the GGBFS. By optimizing ratio between NaOH and Na2SO4, mixtures with improved workability, faster structuration, reasonable setting times, and desirable mechanical properties were achieved. The superior mechanical properties were attributed to a well-packed microstructure consisting of C-(A)-S-H, ettringite, and hydrotalcite in the binary NaOH-Na2SO4 activator systems.

Effect of Sodium Hydroxide and Magnesium Chloride on Magnesium Silicate Cement–Based Glass Waste

The individual effect of sodium hydroxide (NaOH) and magnesium chloride (MgCl2) on the performance of magnesia-based cement is the main focus of this study. Different magnesium oxide–glass waste (MgO–GW) mixtures of MgO-to-SiO2 molar ratios (MgO/SiO2) of 1, 2, and 3 were prepared and characterized. The results revealed that the mixture having MgO/SiO2=2 showed the best performance at all curing ages. The addition of 3% by weight NaOH significantly enhanced the mechanical properties of the MgO–GW mixture at MgO/SiO2=2. Further addition of NaOH (5% and 7% by weight) caused a notable reduction in the compressive strength values, suggesting the negative effect of high NaOH content on the binding capacity of the produced binder. Increasing the MgCl2 content up to 5% by weight improved the performance of the fabricated cement; meanwhile, the addition of 7% by weight MgCl2 showed the lowest effect. Furthermore, pH is regarded as the key point that affects the performance of magnesia-based cement materials. Two hydration mechanisms were identified, depending on the type of chemical admixture. NaOH increased the pH of the cementitious system, accompanied by speeding up the formation rate of magnesium silicate hydrate (M-S-H) through the improvement of the dissolution of the silicate network within the GW material. Another mechanism was detected in the MgCl2–MgO–GW composite, in which an extra magnesium oxychloride phase (Phase 5: 5 Mg (OH)2·MgCl2·8H2O) was formed besides M–S–H, yielding hardened samples with the highest mechanical properties. Hence, the results herein show that desirable NaOH and MgCl2 contents enhance the feasibility of utilizing GW to produce a high-performance, eco-friendly binder.

Pemanfaatan Limbah Sabut dan Tempurung Kelapa Sawit sebagai Silica Gel

The increase in the area of oil palm in Indonesia also causes an increase in the amount of palm oil waste. Waste in the form of coir and palm shells is thrown away. While the content of silica (SiO2) in both materials is feasible to be utilized. Silica gel is a form of utilization of oil palm coir and shells. The results of X-Ray Fluorescence (XRF) analysis showed that the silica (SiO2) content in palm coir ash was 27.5%, while 36.10% was in palm shell ash. Silica gel is an adsorbent produced by the sol-gel method, namely the formation of a gel derived from precursor compounds. The precursor compound in the formation of silica gel is sodium silicate solution (Na2SiO3) which is produced from the extraction process of coir ash and palm shells using sodium hydroxide (NaOH) solvent. The concentration of NaOH used varied, namely 1, 3, 5, 7, and 9 M. The aging times used for the formation of silica gel also varied, namely 4, 8, 12, 16, and 20 hours. Dry silica gel with the highest quantity of 5.4115 grams was obtained by adding NaOH with a concentration of 9 M and a aging time of 20 hours. While the silica gel which has the most suitable water content and Fourier Transform Infra Red (FTIR) graphic pattern with Kiesel Gel 60 G is silica gel resulting from the addition of 3M NaOH with a aging time of 8 hours. However, the results of the Structural Equation Modeling (SEM) analysis of silica gel showed results that were not in accordance with silica gel in general.

Influence of free ammonia extraction in methane production from human urine

ABSTRACT Human urine has a high chemical oxygen demand (COD) content which makes anaerobic treatments potentially appropriate for the management of yellow waters, allowing for energy recovery. However, its high N content makes this treatment challenging. The present work studied the viability of performing an anaerobic digestion process for COD valorization on a real (not synthetic) urine stream at laboratory scale. To deal with nitrogen inhibition, two different ammonia extraction systems were proposed and tested. With them, a proper evolution of acidogenesis and methanogenesis was observed. Nitrogen was recovered in the form of ammonium sulphate, which could be used for agriculture, in two different ways: ammonia extraction from the urine stream before feeding the reactor and in situ extraction in the reactor. The first method, which proved to be a better strategy consisted in a desorption process (NaOH addition, air bubbling and acid (H2SO4) absorption column, HCl for final pH adjustment) whereas the in situ extraction in the reactor consisted of an acid (H2SO4) absorption column installed in the biogas recycling line of both reactors. Stable methane production over 220 mL/g COD was achieved and methane content in the biogas was stable around 71%.

Alternative dental impression fillers made of nanorod glutinous rice flour particles through precipitation

In this work, nanorod particles were synthesized from a locally available source, glutinous rice flour, using sodium hydroxide (NaOH) through a simple precipitation process. The synthesized nanofillers were then presented as an alternative organic filler for dental impression application to support the making of a diagnostic and working model. Dynamic Light Scattering, Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy, x-ray Diffraction, Energy Dispersive Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Colorimeter were used to characterize the fillers. The particle size measurement, morphology interaction, and composition of glutinous rice flour nanorod particles were also investigated. The cell viability using 3T3L1 cells was assessed to determine the safety of nanorod particles using the MTT assay and trypan blue solution. All treated samples exhibit a change in particle morphology from polyhedral to rod. Additionally, a decrease in crystallinity, dehydration, and gelatinization temperature was observed. The functional group interacting with sodium hydroxide also changes slightly after size reduction. The samples treated with 3000 centrifugation speed without surfactant addition showed changes from the control sample’s 3931.71 nm to the smallest average width particle size of 73.26 nm with an average length of 865.15 nm. All of the treated samples with NaOH and NaOH-surfactant additions met the non-cytotoxicity acceptance criteria in the range of 73.54%–99.58%, according to the cell viability results. The incorporation of 15 wt% of the synthesized nanorod fillers resulted in a 20 μm continuous line as the impression materials specimen, yielding a satisfactory detail reproduction test result. In conclusion, nanorod particles with biocompatible properties have been successfully manufactured and can potentially be used in the future as an alternative dental impression filler materials.

Minimising Leachate Wastewater Generated from NaOH-Catalysed Biodiesel Synthesis from Methanol

Currently, energy generation based on fossil fuels is producing negative environmental impacts; two of the main symptoms of these impacts are water pollution and climate change. Consequently, the search for new technologies to satisfy the energy demand must have the goal to minimise possible impacts to the environment. There are alternatives with biofuels and, among them, biodiesel. The cheapest reaction pathway for biodiesel production is the transesterification of triglycerides by methanol in the presence of sodium hydroxide; however, this option can contaminate large volumes of water used in the final leach of the biodiesel product. Therefore, a feasible way of producing this biofuel while simultaneously minimising leaching water will be environmentally friendly and will improve economical savings. The present study developed an experimental design in order to minimise the addition of NaOH during biodiesel production by the basic homogeneous pathway. The best operating conditions were 46 °C, methanol in situ 7.5% v/v and NaOH 0.035 M. These conditions allowed to reduce the leaching water amount by 25% compared to techniques reported in the literature; however, the yield to biodiesel decreased from 98 wt.% to 87 wt.% when a model waste oil was used instead of virgin oil.

Concentrated effect of drying agents on mechanical performance of clay soil

In modern construction, more and more attention is paid to the roadbed quality. At the same time, in most regions of the Russian Federation there is a shortage of natural building materials of the required quality. In this regard, methods of stabilizing natural clay soils should be developed to satisfy the regulatory documentation.Purpose: The chemical additive effect on mechanical properties of clay soil.Methodology: The proposed method of concentrated effect of drying agents (lime, active fly ash) can potentially improve the mechanical performance of clay soils, i.e., strengthen the soil. Compressive strength testing of clay soil (light powdery loam) includes its treatment in hydrated lime in the amount of 2, 4 and 6 wt.%, hydrated high-calcium fly ash in the amount of 4, 8 and 12 wt.%, and a combination of slaked lime and chemical additives-accelerators (CaCl2, FeSO4, NaOH) in the amount of 0.5 and 1.0 % of the dry soil mass.Research findings: Even small amounts of lime improve the clay soil strength, which exceeds the effect from the fly ash introduction by 194 %. CaCl2 and NaOH additives significantly accelerate the strength gain. The introduction of FeSO4 improves the strength gain kinetics at the first stage (up to 7 days) and further causes a complete destruction of the material structure. The compaction also shows a significant decrease in the tensile strength during the time between the dry agent introduction and compaction.

Green synthesis of Ag/Ag2O nanoparticles on cellulose paper and cotton fabric using Eucalyptus globulus leaf extracts: Toward the clarification of formation mechanism

The present study reports on phenolic compounds profile of Eucalyptus globulus leaf extracts and exhibiting their role in obtaining silver nanoparticles (AgNP) by a green method on paper and fabric supports with or without addition of NaOH. To know the mechanism involved in the formation of AgNP, FTIR, UV–Visible spectrophotometry and UHPLC-QTOF-MS analyzes were carried out of E. globulus extracts before and after the synthesis of AgNP. The FTIR, UV–Visible spectrophotometry analyzes identified phenolic compounds, and to a lesser extent reducing sugars mainly participate as reducing agents in the formation of AgNP, while phenolic compounds would participate as stabilizing agents. UHPLC-QTOF-MS analyzes identified derived from gallic acid play an important role in AgNP formation. AgNPs were characterized in their morphology and structure by SEM-EDS, TEM-SAED, XRD, UV–Vis diffuse reflectance and TGA. The results indicate the formation of Ag and/or Ag2O nanoparticles depending on the influence of NaOH in the reaction system. Furthermore, the support used (paper or fabric), it would influence the concentration of AgNPs formed, the consumption of phenolic compounds, the antibacterial activity and band-gap of AgNPs synthesized. This study provides evidence of a simple process to support AgNP on cellulose and providing key information towards the definitive clarification of the mechanism of formation of AgNP by green synthesis.