Higher Concentrations Of Sodium Hydroxide Research Articles

Evaluating a Novel Fly Ash Resin-Reinforced Cement's Interactions under Acidic, Basic, High-Salinity, and High-Temperature Conditions.

The ability of cement to withstand harsh conditions is one of its most vital properties, especially in hydrocarbon wells, due to their association with high temperatures, high pressures, acidic components, and erosion. Conventional cement is prone to failure under extreme conditions and is also a costly component in oil and gas wells. This research evaluated the ability of a newly developed cement composed of fly ash reinforced with epoxy resin to withstand the harsh conditions of oil and gas wells. The novel cement was tested for its ability to resist high concentrations of hydrochloric acid (HCl) and sodium hydroxide (NaOH), high salinity, high temperatures, high pressures, gaseous and supercritical carbon dioxide (CO2), and crude oil. Results showed that the novel cement had an overall excellent ability to perform under extreme conditions. The performance of the cement was a strong function of the fly ash concentration, with an increase in the fly ash concentration resulting in improvement in the cement. For all tests, the highest degradation for the novel cement that occurred was 0.62% after 7 continuous days of exposure, which is considered an extremely low value. This shows that the novel cement has a strong ability to maintain its integrity under extreme conditions.

Assessing the impact of sanitization methods for regenerated cellulose ultrafiltration/diafiltration membrane on membrane integrity and protein quality.

Ultrafiltration/diafiltration (UF/DF) is typically the final step in downstream processing of recombinant monoclonal antibody (mAb) products, which serves for protein concentration and buffer exchange. For UF/DF membranes composed of regenerated cellulose (RC), sanitization with 0.1 M sodium hydroxide is generally recommended by the supplier, but it may not be sufficient for reducing bioburden during large scale manufacturing. Therefore, more stringent sanitization methods for RC membranes are required. However, chemicals used in such sanitization step may disrupt membrane integrity, while the corresponding residuals may reduce product quality. Previous work has shown that high concentration of sodium hydroxide or addition of peracetic acid (PAA) can effectively reduce bioburden, but their effects on the RC membranes remain unknown. In this work, we assessed the impact of two sanitization methods, 0.5 M sodium hydroxide and 30 mM PAA in combination with 0.5 M sodium hydroxide, on membrane integrity and protein quality of Millipore and pall corporation (PALL) membranes. Both methods showed a similar impact as the control after performing 15 cycles. However, the addition of PAA may cause residual chemical concerns, therefore, 0.5 M sodium hydroxide was recommended as an effective and safe sanitization method for RC UF/DF membranes.

Colorimetric Sensing of Gram-Negative and Gram-Positive Bacteria Using 4-Mercaptophenylboronic Acid-Functionalized Gold Nanoparticles in the Presence of Polyethylene Glycol.

Gold nanoparticles (GNPs) have been used as detection probes for rapid and sensitive detection of various analytes, including bacteria. Here, we demonstrate a simple strategy for bacterial detection using GNPs functionalized with 4-mercaptophenylboronic acid (4-MPBA). 4-MPBA can interact with peptidoglycan or lipopolysaccharides present in bacterial organelles. After the addition of a high concentration of sodium hydroxide (NaOH), the functionalization of the surface of 50 nm GNPs with 4-MPBA (4-MPBA@GNPs) in the presence of polyethylene glycol results in a color change because of the aggregation of 4-MPBA@GNPs. This color change is dependent on the amount of bacteria present in the tested samples. Escherichia coli (E. coli) K-12 and Staphylococcus aureus (S. aureus) are used as Gram-negative and Gram-positive bacterial models, respectively. The color change can be detected within an hour by the naked eye. A linear relationship is observed between bacterial concentrations and the absorbance intensity at 533 nm; R 2 values of 0.9152 and 0.8185 are obtained for E. coli K-12 and S. aureus, respectively. The limit of detection of E. coli K-12 is ∼2.38 × 102 CFU mL-1 and that of S. aureus is ∼4.77 × 103 CFU mL-1. This study provides a promising approach for the rapid detection of target Gram-negative and Gram-positive bacteria.

PERFORMANCE OF POLYMER GROUTS MADE FROM WASTES FOR PERMEABLE RIGID PAVEMENT CONNECTIONS

This research developed polymer grouts made from wastes such as fly ash, palm oil fuel ash, and silica fume. The selected polymer grouts served as an interlocking key between the StormPav covers and as a grout to seal the gaps between the interlocking keys and StormPav covers. Based on compressive strength and workability of the polymer grouts, mix ratio of resin to fly ash = 1:1.00 was chosen as the grout, while mix ratio of resin to fly ash = 1:1.50 was used to form an interlocking key. Mix ratios of resin to fly ash = 1:1.00 and resin to fly ash = 1:1.50 had a compressive strength of 98.90 MPa and 81.70 MPa, respectively, and flexural strength of 53.00 MPa and 61.90 MPa. Moreover, increasing the fly ash content in polymer grout decreased the water absorption and volume of permeable voids. In terms of shear strength, the mix ratio of resin to fly ash = 1:1.00 performed well as grout, with a determined shear strength of 3.98 MPa. Even after 25 days of exposure to the high concentration of sodium hydroxide, sulphuric acid, sodium chloride, and magnesium sulphate, the determined shear strength met the minimum shear strength requirement of 1.38 MPa as stated by the Iowa Department of Transportation. Therefore, it can be concluded that both selected mix ratios were suitable for use as grout and interlocking key due to their good physical and mechanical properties.

Managing CO2 levels through precipitation-based capture from seawater and electrochemical conversion

With the rise in global greenhouse gas emissions, many studies have sought methods to reduce the accumulation of carbon dioxide (CO2) in the atmosphere. Existing methodologies are primarily based on amine solvents such as monoethanolamine (MEA) and 2-amino-2-methylpropanol (AMP) due to their high carbon absorption capacity and good recyclability. As such, they are used for the capture of CO2 from sequestration sites and its subsequent electrochemical transformation. However, because amines have large enthalpies of reaction, this leads to expensive and energy-intensive processes that limit their capacity for large-scale application. Thus, this study seeks to develop an electrochemical device that can sustain efficient CO2 capture and conversion through precipitation. The dissolved inorganic divalent cation calcium (Ca,2+) reacts with carbon to form carbonate (CO32-) compounds that flow through a thin membrane, facilitating the filtration of the precipitate. We hypothesized that higher alkalinity will produce a greater quantity of CO2 capture, as measured by the change in seawater pH and the mass of precipitate formed. The CO32- compound is, in turn, converted to the industrial fuel formic acid (HCOOH). Through our experimentation, we found a statistically significant difference between the measured pH of seawater before and after CO2 capture (p < 0.001), thus suggesting this setup as a proof of concept for the effective reduction of ocean acidification. Additionally, we observed an upwards trend as higher concentrations of sodium hydroxide (NaOH) were generally associated with greater changes in pH.

Modifying the resin type of hybrid anion exchange nanotechnology (HAIX-Nano) to improve its regeneration and phosphate recovery efficiency

In order to avoid eutrophication of freshwater systems, regulations all around the world have become increasingly stringent toward the maximum phosphate concentration allowed in wastewater discharges. Traditional phosphate removal methods such as chemical precipitation and enhanced biological phosphorus removal struggle to lower phosphate levels to the new requirements. Hybrid anion exchange nanotechnology (HAIX-Nano) is composed of a selective adsorption material able to remove phosphate down to levels close to zero. Moreover, HAIX-Nano is not affected by intermittent flow and does not produce sludge making it an interesting alternative. The regeneration process of HAIX-Nano typically requires a chemical solution with a high concentration of sodium hydroxide (NaOH) and sodium chloride (NaCl) (2–5% w/w of each). To lower the environmental impact and the operational cost of the technology, this study aims to enhance the HAIX-Nano regeneration efficiency. Therefore, the backbone of HAIX-Nano, which is normally a strong base anionic (SBA) resin, was changed for a weak base anionic (WBA) resin. The resulting material (WBA-2) exhibited a higher adsorption capacity than the traditional version of HAIX-Nano (SBA-1) under the tested conditions, while also showing a much higher regeneration efficiency. For a desorption solution of only 0.4% NaOH and no NaCl, WBA-2 showed an average regeneration efficiency of 78 ± 1% compared to SBA-1 with 24 ± 1%.

Chemical Inactivation of Prions Is Altered by Binding to the Soil Mineral Montmorillonite.

Environmental routes of transmission contribute to the spread of the prion diseases chronic wasting disease of deer and elk and scrapie of sheep and goats. Prions can persist in soils and other environmental matrices and remain infectious for years. Prions bind avidly to the common soil mineral montmorillonite, and such binding can dramatically increase oral disease transmission. Decontamination of soil in captive facilities and natural habitats requires inactivation agents that are effective when prions are bound to soil microparticles. Here, we investigate the inactivation of free and montmorillonite-bound prions with sodium hydroxide, acidic pH, Environ LpH, and sodium hypochlorite. Immunoblotting and bioassays confirm that sodium hydroxide and sodium hypochlorite are effective for prion deactivation, although montmorillonite appears to reduce the efficacy of hypochlorite. Acidic conditions slightly reduce prion infectivity, and the acidic phenolic disinfectant Environ LpH produces slight reductions in infectivity and immunoreactivity. The extent to which the association with montmorillonite protects prions from chemical inactivation appears influenced by the effect of chemical agents on the clay structure and surface pH. When clay morphology remains relatively unaltered, as when exposed to hypochlorite, montmorillonite-bound prions appear to be protected from inactivation. In contrast, when the clay structure is substantially transformed, as when exposed to high concentrations of sodium hydroxide, the attachment to montmorillonite does not slow degradation. A reduction in surface pH appears to cause slight disruptions in clay structure, which enhances degradation under these conditions. We expect our findings will aid the development of remediation approaches for successful decontamination of prion-contaminated sites.

Lactic Acid Production from High Concentration of Invert Sugar in Semi-Batch Reactor

The objective in this study is the production of high yield of lactic acid production from invert sugar in alkaline degradation at mild reaction condition. The invert sugar was immediately and continuously added into an alkaline solution in a batch and semi-batch reactor, respectively. The effect of batch and semi-batch, initial concentration of sodium hydroxide and initial of concentrated raw materials were studied. Semi-batch provided better yield than batch reactor. High sodium hydroxide concentration with low invert sugar in semi-batch operation was found to have high lactic acid. The feed concentration of invert sugar at 30, 45 and 70% provided lactic acid yield around 65-68% for excess sodium hydroxide base at 50°C and 10 hr.

Removal of heat stable salts from N-methyldiethanolamine wastewater by anion exchange resin coupled three-compartment electrodialysis

Heat stable salts (HSS) are well-known degradation products of gas desulfurization using N-methyldiethanolamine (MDEA) solvents. Excessive HSS content causes a decrease in desulfurization efficiency, a decrease in the active ingredients of MDEA, and the corrosion of pipelines. In this paper, a self-designed two-compartment electrodialysis (ED) stack, a three-compartment electrodialysis (TED) stack, and an anion exchange resin coupled three-compartment electrodialysis (RTED) stack were assembled to remove the HSS from spent MDEA wastewater. The HSS desalination mechanisms of the three electrodialyzers were investigated, and their HSS removal efficiencies and losses of MDEA were investigated and compared. According to the results, approximately 93.84% of HSS were removed from the spent MDEA wastewater in the RTED, 7.88% higher than those in the TED and 28.57% higher than those in the ED. The loss of MDEA for the RTED was 3.78%, which is 1.78% lower than that for the TED and 17.29% lower than that for the ED. A relatively high sodium hydroxide (NaOH) concentration in the NaOH compartment, but no more than 3%, is beneficial for both improving the HSS removal efficiency and decreasing the loss of MDEA in TED and RTED. Much less fouling of the anion exchange membranes occurs in the RTED process than in the ED process because of the effect of the filled resin and the NaOH compartment. The cost of RTED is estimated to be US $0.88/kg HSS, which is far lower than that of both ED and TED.

Geopolymer bricks made from less active waste materials

The current study aims at investigating the production feasibility of the geopolymer bricks using the waste materials emanated from the washing process of sand and gravel in aggregate industries. Geopolymer is a material originated by inorganic polycondensation as a result of the alkali activation of aluminosilicate materials. Geopolymer bricks seem to be advantageous due to the low demand for energy and the significant incorporation of wastes. The production of geopolymers from pozzolanic or aluminosilicate rich materials is very common. However, few studies have been carried out on the less-active materials such as waste materials of aggregate industries as raw materials for producing geopolymers. For this purpose, the influence of three parameters, sodium hydroxide concentration (4, 8 and 12 M), calcium hydroxide content (5%,10%, and 15%), and curing temperature (70 °C and 105 °C), on the physical and mechanical properties of geopolymer bricks was investigated using compressive strength, SEM micrographs, XRD analysis, water absorption, and bulk density. The results indicate that higher sodium hydroxide concentration caused forming a less porous and a more amorphous microstructure, and yielded higher strengths and lower water absorption. The mixtures with higher calcium hydroxide content had higher compressive strengths (up to 75 MPa and 36 MPa at dry and wet conditions, respectively) and a more stable microstructure, however, incorporation of calcium hydroxide at levels higher than 20% results in lower compressive strengths, lower densities, and higher water absorption contents. Increasing curing temperature from 70 °C to 105 °C increased significantly the compressive strength.

Durability of chemically modified sisal fibre in cement-based composites

The degradation of sisal fibre in a cement-based matrix due to the highly alkaline environment reduces the strength of the composite. In this research, to avert this degradation, alkaline treatment and acetylation were respectively performed with sodium hydroxide (NaOH) and Acetic Acid or Acetic Anhydride to improve the resistance of the fibre to alkaline attack. In addition, single fibre pull-out (SFP) tests were performed to evaluate the influence of chemical treatment on fibre strength, fibre-matrix interaction and also determine the critical fibre length. Specimens were tested in indirect tension (flexure) at 28 days to determine the strength of the composite. Additional ageing tests by extended curing in water at 24 °C, lime saturated hot water at 70 °C, and alternate cycles of wetting and drying were done. Aged samples were further tested at 90 days to evaluate the durability of the fibre. It was found that a combination of alkali treatment and acetylation was the most effective treatment condition, followed by that of alkali treatment at low concentrations of sodium hydroxide. At higher concentrations of sodium hydroxide, a significant reduction in strength was observed. Chemical treatment improves the durability of sisal fibres in concrete, albeit slight degradation still occurs.

A practicable method to prepare nitrated proteins with peroxynitrite and low concentration of sodium hydroxide.

Peroxynitrite is an ion acting as a powerful oxidant and nucleophile, which plays a key role in the inflammation and aging process by nitrating tyrosine or tryptophan residues of the proteins. Nitration of a target protein is considered to be a proper method to study the behavioral change of the proteins being nitrated. The commonly used methods for peroxynitrite preparation in vitro usually contain high concentration of sodium hydroxide, which easily induces hydrolysis of target proteins. Accordingly, the method for peroxynitrite preparation was optimized in vitro by changing the sequence of hydrochloric acid and sodium hydroxide added. After different amount of hydrochloric acid added to the system following sodium nitrite, peroxynitrite can be yielded in a concentration up to 60mM with sodium hydroxide as low as 17mM. More importantly, biological activity of the target protein was well maintained after protein nitration since low sodium hydroxide was used.

A Review Study on the Characterization of Geopolymer Concrete

Ordinary Portland cement (OPC) is the essential binding material to produce the OPC concrete. Production of OPC is recently attaining a rate of 2.6 billion ton per year worldwide and growing 5% annually. OPC contributes at rate of 5 – 8% of human-worldwide CO2 emissions which are the greenhouse gases pollute the atmosphere. Geopolymer concrete (GPC) is a creative, sustainable, economical and eco-friendly material for construction industry, which is a suitable alternative to the OPC concrete, able to extensively curb the CO2 emissions. To prepare this kind of concrete, a combination of pozzolanic material such as fly ash (FA), and/or ground granulated blast furnace slag (GGBS) rich with silica and alumina can react with alkaline activator solution producing aluminosilicate gel, acting as a superb binding material for fine and coarse aggregates under special conditions of curing. This study highlights the recent explorations on geopolymer mortars and concrete. Effect of chemicals such as sulphuric acid, effect of fly ash partial replacement with different binding materials, effect of concentration of alkaline activator solutions and the effect of temperature and time of curing variation have been discussed on durability and mechanical properties of geopolymer concrete. Results have shown superb resistance of geopolymer concrete to the detrimental effects of sulphuric acid on weight and compressive strength. Furthermore, fly ash partial replacement with silica fume, OPC or GGBS, or nanosilica inclusion in GPC has a positive effect on the GPC properties. Finally, using high concentration of sodium hydroxide has a detrimental effect on GPC properties.

Preparation and Reaction Mechanism Characterization of Alkali-activated Coal Gangue-Slag Materials.

In this paper, slag is used as a calcium source to make alkali-activated coal gangue–slag (AACGS) based material. The reaction mechanism of AACGS materials was discussed in depth by means of XRD, FT-IR, 29Si MAS-NMR (nuclear magnetic resonance) and SEM-EDS (energy dispersive spectrometer). The experimental results show that coal gangue can be used as a raw material for preparing alkali-activated materials. The liquid–solid ratio is the most influential factor on AACGS paste fluidity and strength, followed by slag content. As the modulus of sodium hydroxide increases, the depolymerization process of the reactant precursor is accelerated, but the high sodium hydroxide concentration inhibits the occurrence of the early coal gangue–slag polycondensation reaction, and exerts little effect on the 28 d compressive strength. Ca2+ in the slag promotes exchange with Na+, and the product is converted from N-A-S-H gel to C-(A)-S-H gel, and C-(A)-S-H is formed with higher Ca/Si ratio with the increase of slag content. The slight replacement of coal gangue by slag can greatly improve the reaction process and the strength of AACGS materials.

Characterization of MWCNT-PEDOT: PSS Nanocomposite Flexible Thin Film for Piezoresistive Strain Sensing Application

Multiwalled carbon nanotubes (MWCNTs) were synthesized by the reduction of ethyl alcohol with sodium borohydride (NaBH4) under a strong basic solvent with the high concentration of sodium hydroxide (NaOH). Nanocomposites of different concentration of MWCNT dispersed in poly(3,4-ethylene dioxythiophene) polymerized with poly(4-styrene sulfonate) (PEDOT:PSS) were prepared and deposited on a flexible polyethylene terephthalate (PET) polymer substrates by the spin coating method. The thin films were characterized for their nanostructure and subsequently evaluated for their piezoresistive response. The films were subjected to an incremental strain from 0 to 6% at speed of 0.2 mm/min. The nanocomposite thin film with 0.1 wt% of MWCNT exhibits the highest gauge factor of 22.8 at 6% strain as well as the highest conductivity of 13.5 S/m. Hence, the fabricated thin film was found to be suitable for piezoresistive flexible strain sensing applications.

Response to Alirocumab in Homozygous Familial Hypercholesterolemia: a Case Report

Pure-silica IZM-2 was synthesized for the first time, and the concentration of sodium hydroxide used during synthesis affected the phase purity and size of crystals. Most of the micropores in calcined pure-silica IZM-2 that was synthesized in the presence of high concentrations of sodium hydroxide were inaccessible to N2 adsorption; however, the micropores could be rendered accessible by applying either of two different post-synthetic treatments. Pure-silica IZM-2 could also be synthesized without sodium ions using the hydroxide version of the template. In this case, the micropores were accessible to N2 directly after calcination. The size of pure-silica IZM-2 crystals obtained increased with the concentration of sodium hydroxide, with the highest concentrations giving spherical and micrometer-sized aggregates of pure-silica IZM-2 that consisted of intergrown particles (60–500 nm). The nature of the defects in pure-silica IZM-2 was studied with a combination of 1H, and 29Si solid-state NMR spectroscopy. As expected, direct-polarization 29Si NMR spectroscopy showed that the number of non-condensed silica groups decreased upon calcination. Calcined samples also showed broader 29Si NMR bands for the fully condensed silica moieties, which indicated a broader distribution of bond angles and/or bond lengths. The siloxy and silanol groups in calcined pure-silica IZM-2 were accessible to protonation as determined by 1H NMR spectroscopy. We could not determine the structure of pure-silica IZM-2 in its aggregated form; however, further studies of the synthetic conditions could yield larger, non-aggregated crystals that would facilitate structural determination.

The effects of sodium hydroxide and potassium permanganate treatment on roughness of coconut fiber surface

The purpose of this study was to determine the grade of roughness of coconut fiber surface as result of sodium hydroxide and potassium permanganate treatment. Research stages are soaking for 3 hours, testing, and data processing. Coconut fiber is soaked in 5%, 10%, 15%, 20% sodium hydroxide solution. Then soaked in 0.25%, 0.5%, 0.75% and 1% potassium permanganate solution. After that, the coconut fiber is dried in the oven at 90 °C for 5 hours. Thereafter, measurement of surface roughness. The measurement of surface roughness was did in two methods namely SEM, and surface roughness gauge. Based on the results of the tests, it was concluded that the higher concentrations of sodium hydroxide and potassium permanganate solutions gave higher grades of surface roughness compared with untreated fibers.

Microporous pure-silica IZM-2

Pure-silica IZM-2 was synthesized for the first time, and the concentration of sodium hydroxide used during synthesis affected the phase purity and size of crystals. Most of the micropores in calcined pure-silica IZM-2 that was synthesized in the presence of high concentrations of sodium hydroxide were inaccessible to N2 adsorption; however, the micropores could be rendered accessible by applying either of two different post-synthetic treatments. Pure-silica IZM-2 could also be synthesized without sodium ions using the hydroxide version of the template. In this case, the micropores were accessible to N2 directly after calcination. The size of pure-silica IZM-2 crystals obtained increased with the concentration of sodium hydroxide, with the highest concentrations giving spherical and micrometer-sized aggregates of pure-silica IZM-2 that consisted of intergrown particles (60–500 nm). The nature of the defects in pure-silica IZM-2 was studied with a combination of 1H, and 29Si solid-state NMR spectroscopy. As expected, direct-polarization 29Si NMR spectroscopy showed that the number of non-condensed silica groups decreased upon calcination. Calcined samples also showed broader 29Si NMR bands for the fully condensed silica moieties, which indicated a broader distribution of bond angles and/or bond lengths. The siloxy and silanol groups in calcined pure-silica IZM-2 were accessible to protonation as determined by 1H NMR spectroscopy. We could not determine the structure of pure-silica IZM-2 in its aggregated form; however, further studies of the synthetic conditions could yield larger, non-aggregated crystals that would facilitate structural determination.

Temperature rise and initial shrinkage of alkali-activated fly ash cement pastes

This paper reports on core temperature development and initial shrinkage of fly ash cement pastes activated with sodium hydroxide solution at different concentrations during elevated-temperature curing at 60°C. The results indicate that a high sodium hydroxide concentration might result in a substantial rise in the core temperature of samples, dependent on the mould size and ratio of paste to oven volume. An increase in alkali concentration was also found to increase the initial shrinkage of the pastes during elevated-temperature curing. Excessive initial shrinkage and temperature increase might lead to the appearance of internal stresses in the pastes, which can affect the material performance.

Removal of Oxidation Fragments from Multi-walled Carbon Nanotubes Oxide Using High and Low Concentrations of Sodium Hydroxide

Modification of multi-walled carbon nanotubes surface (MWCNT) using the mixture of $${{{\rm HNO}}_{3}/{{\rm H}}_{2}{{\rm SO}}_{4}}$$ is widely employed for MWCNT surface oxidation, but it also leads to shortening and thinning of the CNT layers causing fragmentation. The carbonaceous fragments had adsorbed on the surface is not removed from the sample in conventional treatments; however, the addition of NaOH successfully cleans the oxidized material. In this article, MWCNT was functionalized using $${{{\rm HNO}}_{3}/{{\rm H}}_{2}{{\rm SO}}_{4}}$$ as oxidizing agent and evaluate the impact of using high and low concentrations of NaOH to purify CNT oxide. The presence of oxidized groups as hydroxyl and carboxyl has been demonstrated by FTIR. The thermal stability of MWCNT and MWCNT-O after and before purification was studied by TGA, and the degree of its crystallinity was examined by XRD. The defect degree occurs during the oxidation process was confirmed by Raman spectroscopy. TEM images showed the presence and the absence of wrinkles and the adsorbed carbonaceous fragments.