Alkali Hydroxide Research Articles

Novel Amino Acid Derivatives of Quinolines as Potential Antibacterial and Fluorophore Agents

A new series of amino acid derivatives of quinolines was synthesized through the hydrolysis of amino acid methyl esters of quinoline carboxamides with alkali hydroxide. The compounds were purified on silica gel by column chromatography and further characterized by TLC, NMR and ESI-TOF mass spectrometry. All compounds were screened for in vitro antimicrobial activity against different bacterial strains using the microdilution method. Most of the synthesized amino acid-quinolines show more potent or equipotent inhibitory action against the tested bacteria than their correspond esters. In addition, many of them exhibit fluorescent properties and could possibly be utilized as fluorophores. Molecular docking and simulation studies of the compounds at putative bacterial target enzymes suggest that the antimicrobial potency of these synthesized analogues could be due to enzyme inhibition via their favorable binding at the fluoroquinolone binding site at the GyrA subunit of DNA gyrase and/or the ParC subunit of topoisomerase-IV.

Key activity descriptors of nickel-iron oxygen evolution electrocatalysts in the presence of alkali metal cations

Efficient oxygen evolution reaction (OER) electrocatalysts are pivotal for sustainable fuel production, where the Ni-Fe oxyhydroxide (OOH) is among the most active catalysts for alkaline OER. Electrolyte alkali metal cations have been shown to modify the activity and reaction intermediates, however, the exact mechanism is at question due to unexplained deviations from the cation size trend. Our X-ray absorption spectroelectrochemical results show that bigger cations shift the Ni2+/(3+δ)+ redox peak and OER activity to lower potentials (however, with typical discrepancies), following the order CsOH > NaOH ≈ KOH > RbOH > LiOH. Here, we find that the OER activity follows the variations in electrolyte pH rather than a specific cation, which accounts for differences both in basicity of the alkali hydroxides and other contributing anomalies. Our density functional theory-derived reactivity descriptors confirm that cations impose negligible effect on the Lewis acidity of Ni, Fe, and O lattice sites, thus strengthening the conclusions of an indirect pH effect.

Development of expansive soil geopolymer binders for use in waste containment facility

Waste containment facilities require liners and covers for safe waste disposal, which can be efficiently achieved using robust green technologies. In the present study, a systematic approach was adopted towards the development of reliable expansive soil geopolymers suitable for waste containment application. Various factors that influence geopolymerisation were considered including the precursor type (PT), precursor content, liquid alkali hydroxide type (LT), activator-to-precursor ratio (A/P) and method of preparation. Multiresponse optimisation for permeability, volumetric shrinkage and unconfined compressive strength was executed to achieve soil geopolymers that satisfy the regulatory requirement as hydraulic barrier materials. This was done using a robust experimental design and the utility concept to prescribe a framework for achieving reliable soil geopolymers. The results obtained show that significant interactions between the factors (PT × LT) and (PT × A/P) affected the response characteristics and consequently the soil geopolymer performance. The aptness of the multiresponse optimisation was confirmed at 95% confidence interval, which revealed that the developed soil geopolymers can be used in waste containment facility under certain conditions. Evidence of the geopolymerisation process was clarified using microstructural analyses. Scanning electron microscopy and energy-dispersive spectroscopy supported the formation of N–A–S–H and K–A–S–H gels. Moreover, diffraction patterns for new minerals such as muscovite and crystobalite were formed, with the disappearance of clay minerals. The presence of aluminosilicate gel binding systems was revealed by Fourier transform infrared spectroscopy. The participation of clay minerals in the geopolymerisation distinguishes the developed expansive soil geopolymer from the conventional geopolymers developed for concrete applications.

Various Effects of Alkali Metal Ions on H2O2 Reduction Reactions at Pt Electrodes

The hydrogen peroxide reduction reaction (HPRR) has attracted much attention because it is involved in the oxygen reduction reaction which is an important cathode reaction in several fuel cell systems. Pt has an excellent electrocatalytic activity toward the HPRR. Thus, the HPRR at Pt electrodes has been widely studied including effects of electrolyte components and additives on it.Katsounaros and Mayrhofer have reported that alkali metal cations such as Li+, Na+, and K+ inhibit the HPRR in basic media [1]. The hydrated alkali metal cations and chemisorbed OH species on Pt, denoted as M+(H2O) x and OHads respectively, non-covalently stabilize each other, leading to the formation of quasi-specifically adsorbed hydrated metal ion clusters that blocks electrochemical reactions. The inhibition becomes stronger as the strength of the non-covalent interaction increases (K+ < Na+ < Li+), and consequently the rest potential decreases in this order, as reproduced in Figure 1a.We have recently found that the HPRR in strongly acidic media is also affected by the alkali metal ions. As shown in Figure 1b, the HPRR is inhibited at U < 0.7 V in the presence of the ions. This indicates that the alkali metal ions inhibit the transport of electroactive species, namely, H+ and H2O2, toward the electrode surface. The HPRR current becomes smaller (in absolute value) in the following order: Li+ < Na+ < K+, that is, the inhibition becomes stronger in the reverse order of the strength of the non-covalent interaction. In this work, to explain this inhibition, we study the HPRR by electrochemical impedance method.Interestingly, the metal ions induce a significance increase in the local pH at the electrode surface (pHs) during the HPRR when the concentration of H2O2 is relatively high, that is, when the HPRR consumes a large amount of H+ [2]. For instance, the pHs becomes strongly basic when 0.01 M H2SO4 + 0.05 M H2O2 + 0.05 M M2SO4 (where M stands for Li, Na, and K) is used as the electrolyte solution. We thus think that the non-covalent interaction can be induced during the HPRR even in the acidic media. Note that the pHs remains acidic in the case of Figure 1b because of the lower concentration of H2O2. In this work, we summarize the above-mentioned effects of the alkali metal ions on the HPRR. REFERENCES [1] I. Katsounaros and K. J. J. Mayrhofer, Chem. Commun., 48, 6660-6662 (2012).[2] Y. Mukouyama, H. Kawasaki, D. Hara, Y. Yamada, S. Nakanishi, J. Electrochem. Soc., 164 (2017) H675. FIGURE CAPTION Figure 1. The current (I) – potential (E) curves for a Pt-plate electrode in basic and acidic solutions measured under potential controlled conditions at a scan rate of 0.01 Vs-1. The basic solutions are 0.05 M alkali hydroxide (denoted as MOH) + 0.01 M H2O2, and the acidic ones are 0.05 M H2SO4 + 0.01 M H2O2 with or without 0.05 M alkali sulfate (denoted as M2SO4). Figure 1

Analisis Pengaruh Konsentrasi Natrium Hidroksida terhadap Sifat Mekanik Biokomposit Berpenguat Serat Sisal

The mechanical properties of natural fibers are continuous development as the alternatively synthetic fibers because of the natural fibers are non-corrosive, lightweight, and environmental advantages. However, these fibers have poor interfacial adhesion properties as the fibers if used as bio-composite material. This problem can be solved by the surface modification method by the sodium hydroxide treatment used to improve the mechanical properties. A sodium hydroxide concentration which it used at 0 wt%, 5 wt%, 10 wt%, and 15 wt% and the sisal fibers were soaked in that a concentration for 2 hours. Furthermore, the bio-composite fabrication is conducted by hand lay-up technique which is using both sisals as the fibers and epoxy resin as the matrix. The tensile test RTG-1250 results show that the maximum mechanical properties, such as strains, Young's modulus, and elongation, was obtained at sodium hydroxide 5 wt% than others where the values of these mechanical properties were 25.334 MPa, 16.111 GPa, and 1.572%, respectively. The morphological evaluation carried out using a scanning electron microscope showed that the alkali sodium hydroxide treatment was improved interfacial adhesion between fiber and matrix. Finally, sodium hydroxide alkali treatment of more than 5% can be able to sisal fiber cracks so that the mechanical properties of bio-composite can decrease continuously.

Effect of Chemical Activators on the Compressive Strength of Cement-Slag Mortar

The reaction of ground granulated blast furnace slag (GGBFS) with water is slower compared to the hydration of ordinary Portland cement. This led researchers to concentrate on increasing the hydration rate of the GGBFS. Previous studies were done by (SCA) showed that GGBFS can be used with activators or a certain amount of Portland cement. Also, they found that alkali hydroxides and GGBFS can be reacted alone without any calcium hydroxide obtained from Portland cement hydration to obtain a strong cement paste in applications. This experimental study conducted by the TS EN 196-1 standard, with the ratio (79:21)% slag to cement and 0%, 1%, 2%, 3% and 4% levels of activators (CaCO3, Ca (OH) 2, Na2SO4, K2SO4 and CaSO4.2H2O); results indicates that with above ratio slag can be used with activator of (Na2SO4, K2SO4 and CaSO4.2H2O), greater compressive strength of 5-6 MPa was obtained at 2 and 7-day curing ages when K2SO4 was used as an activator at the dosages of 3% and 4%, while the activator (CaSO4.2H2O) can improve all ages, and there was not a clear difference among control mixture without activator and slag-mortars activated by CaCO3 and Ca (OH).

KEMAMPUAN PERTUMBUHAN BERAT BADAN TERNAK DOMBA DENGAN 125 – 132 PEMBERIAN PAKAN JERAMI PADI DENGAN PERLAKUAN NATRIUM HIDROK-SIDA (NAOII) SEBAGAI PENGGANTI HIJAUAN

This research was aim to discover weight growth ability of fat tailed sheep livestock which feeds ice straw that was treated by hydroxide alkali ( NaOH). This research was using 10 sheep under 1 year aged which was divided into two groups, per group consist of 5 sheep with average weight was 14 kg for first group and 13.97 kg for second group. Feed treatment for first group was chopped dry rice straw plus NaOH with ratio 2 grams NaOH for 100 grams dry rice straw. Previously, NaOH was dissolved into 600 ml of water then sprayed to the straw till homogenous. Second group was for control, fed with verdant big grass (Pennisentum purpureum). Both of those groups fed with suplement -food called bekatul (rice bran). It quantity was 400 grams per sheep per day. Research was done during 90 days. Data which was taken covering weight increasing and amount of food consumption per sheep per day. The research result showed average of weight increasing for first group was 32.8 grams and the second group was 45.5 grams per sheep per day. Amount of dry water feed consumption per sheep per day (rice bran grasses) for first group was 0.428 kg and for second group was 0.693 grams. Amount of digestible protein consumption and digestible energy per sheep per day for each group was 24.31 grams and 1.299 mcal for first group then 35.32 grams and 2.014 mcal for second group. Therefore weight increasing, amount of consumption (dry matter digestible protein, digestible energy) of second group was better than first group (P < 0,05). Keyword : Rice straw hydroxide alkali (NaOH), Live stock feeds, sheep

Transport and Interfacial Properties of Mixed Molten Carbonate/Hydroxide Electrolytes by Molecular Dynamics Simulations

We use molecular dynamics simulations based on a recently developed force field to obtain the viscosity, ionic conductivity, and liquid–vapor surface tension of molten alkali-metal carbonate–hydroxide mixtures over a range of cation and hydroxide compositions. Recent experimental and simulation studies have suggested that molten carbonates contain non-negligible amounts of hydroxide ions in the presence of water at low partial pressures of CO2. However, due to the high temperatures (≃600 °C or higher) required to melt pure alkali carbonates and their mixtures, there is a lack of experimental thermodynamic and transport data for these molten phases. Here, we deploy a recently parametrized force field for molten alkali carbonates and hydroxides [ J. Chem. Theory Comput. 2020, 16, 5736−5746, DOI: 10.1021/acs.jctc.0c00285] to simulate some physical properties using atomistic molecular dynamics. Our predictions show a consistent decrease in viscosity and an increase in ionic conductivity with increasing hydroxide fractions, whereas a higher Li+ mole fraction leads to an increase in both viscosity and ionic conductivity. The computed surface tension values exhibit an upward trend with higher asymmetry in cation and anion sizes. Structural analysis suggests that in the carbonate–hydroxide melts the smaller/harder ions, OH– and Li+, are more favored at the interface than the larger/softer ions, CO32– and K+/Na+. The current approach provides a systematic route to obtaining physicochemical properties of molten alkali carbonate and hydroxide mixtures over a large domain of chemical compositions and thus can steer future experimental research for molten carbonates and their applications.

NaOH(KOH)-catalyzed vinylation of cellulose with acetylene gas in water

Diverse mercerized celluloses (powder cellulose and kraft pulp) have been successfully vinylated with acetylene in an aqueous solution of alkali metal hydroxides (KOH or NaOH) at 125–140 °C. Depending on the reaction conditions, degree of substitution (DS) of the hydroxyl groups by highly reactive polymerazable vinyloxy groups ranges 0.08–0.73, the yields of vinyl celluloses being 24–75%. The process is accompanied by alkaline degradation of the cellulose macromolecule.

Utilization of waste coir fibre architecture to synthesize porous graphene oxide and their derivatives: An efficient energy storage material

Now-a-day’s lot of researcher interest is directed towards the conversion of bioresources (waste) to carbon-based materials for meeting the demand of sustainable energy. In the present study, we have utilized waste coir fibres for the synthesis of graphene oxide and its derivatives. Microscopic investigation of coir fibre indicates that silica microspheres assembled in a regular pattern inside the cellulose matrix of coir fibre. Here, we have attempted to make water-soluble silica-based compound via reaction of coir with alkali metal hydroxide. Further, heating of water-soluble silicates-cellulose mixture leads to the formation of porous graphene oxide having high specific surface area (1114 m2/g). Doping of sulphur and nitrogen has been done via the chemical route, which leads to enhancement in electronic conductivity. The electrochemical study of bare and doped graphene oxide have been carried out using electrochemical work station. The electrochemical study confirms that nitrogen-doped graphene oxide has highest specific capacitance (278.6 F/g) as compared to bare graphene oxide (166.1 F/g) and sulphur doped graphene oxide (199.2 F/g) at 1 A/g discharge current because of high charge carrier density in nitrogen-doped graphene oxide (9.7 × 1014 cm−3). The galvanic charge-discharge (GCD) stability shows ∼82% capacitance retention after 2000 GCD cycle at 3 A/g of nitrogen-doped graphene. The above approach for conversion of low-value coir fibre to high-value energy storage material (graphene oxide) would certainly be interest of the researchers working in the field of energy storage, environmental pollution control, waste management, materials science, sustainable chemistry and engineering for achieving the goal of cleaner production technologies for better environmental sustainability.

CELLULOSE DERIVATIVES BY ETHERS

ABSTRACT Powdered cellulose etherified to primary, secondary, tertiary, and combination of primary and tertiary carbons contains halide or an epoxide compound obtains Methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methylcellulose (OH group replaced to OR) in presence of an alkali metal hydroxide in high pressure and thermal conditions, also produced to different grades where you played a viscosity parameter. Key Words: cellulose, alkali cellulose, etherfication.

Long-Term Behavior and Durability of Alkali-Activated Clay Mortars.

The need to increase the durability of clay-based materials, due to their inherent low strength and vulnerability in contact with water, led researchers to examine different options. In this paper, clay mortars were produced using four different activating solutions. Alkali hydroxides, alkali carbonates, and alkali silicates activating solutions were used. Interest is given to long term properties while their behavior to wetting–drying and freeze–thaw cycles is recorded. In total, the results of the experiments indicated the positive effect of the potassium metasilicate on mechanical characteristics presenting, however, low performance at wetting–drying. The combination of sodium metasilicate with sodium hydroxide solution has also presented a positive effect on both mechanical and physical properties. In contrast, sodium carbonate acted better in enhancing physical properties and granting water-resistant abilities. Moreover, the performance of the specimens mixed with water–glass addition presented excellent volume stability and low mass loss in durability tests.

SYNTHESIS OF CROSPOVIDONE DIFFERENT PROCESS

ABSTRACT Crospovidone is a super-disintegrant and is a thermal polymer; crospovidone is a homopolymer of N-Vinyl-2- pyrrolidone; it is a random polymer of N-Vinyl-2-pyrrolidone cross-linked with (Z)-3-ethylidene-1- vinylpyrrolidone-2-one. In this article, the overview is how to synthesise crospovidone by different processes like the main theme, is direct heating of N-Vinyl-2-pyrrolidone with alkali metal hydroxides in the presence of water. Key Words: Crospovidone, Thermal Polyme

The effect of temperature, time of curing and Na2O/SiO2 molar ratio on mechanical and chemical properties of geopolymer cement

The geopolymer cement is a suitable alternative material for Portland cement due to their environmental compatibility, low curing temperature, and high strength. In this research, Kaolin was used as a raw material for the construction of a geopolymer cement, while sodium hydroxide was an alkali hydroxide. Kaolin is calcined at 750 °C to obtain meta-kaolin. Geopolymer samples were prepared at various curing temperatures (25, 50, and 75 °C), different curing times (3, 7, 21, 28, and 60 days) and with different activator ratios (0.6-0.9). The thermal analysis of kaolin was done via DTA/TGA. Investigation on the geopolymer cement structure and phases were performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and magic angle spinning nuclear magnetic resonance (MAS-NMR). Also, the effects of temperature and time of curing and Na2O/SiO2 molar ratio were studied. The results showed that the maximum compressive strength was 115MPa, which obtained at a molar ratio of Na2O/SiO2=0.9, a curing time of 60 days, and a curing temperature of 75°C. The microstructure of cement was studied using scanning electron microscopy (SEM).

Alkali-cation-incorporated and functionalized iron oxide nanoparticles for methyl blue removal/decomposition

Enhancing the rate of decomposition or removal of organic dye by designing novel nanostructures is a subject of intensive research aimed at improving waste-water treatment in the textile and pharmaceutical industries. Despite radical progress in this challenging area using iron-based nanostructures, enhancing stability and dye adsorption performance is highly desirable. In the present manuscript alkali cations are incorporated into iron oxide nanoparticles (IONPs) to tailor their structural and magnetic properties and to magnify methyl blue (MB) removal/decomposition capability. The process automatically functionalizes the IONPs without any additional steps. The plausible mechanisms proposed for IONPs incubated in alkali chloride and hydroxide solutions are based on structural investigation and correlated with the removal/adsorption capabilities. The MB adsorption kinetics of the incubated IONPs is elucidated by the pseudo second-order reaction model. Not only are the functional groups of –OH and –Cl attached to the surface of the NPs, the present investigation also reveals that the presence of alkali cations significantly influences the MB adsorption kinetics and correlates with the cation content and atomic polarizability.

Alkali-metal-ions promoted Zr-Al-Beta zeolite with high selectivity and resistance to coking in the conversion of furfural toward furfural alcohol

Zirconium-substituted zeolites prepared by post-synthetic procedure have demonstrated excellent performance in the upgrading process of biomass platform compounds owing to the unique Lewis acid character. However, many pressing questions still surround these materials, especially relating to specific conversion, catalyst stability and substrate scalability. In the present study, a simple alkaline treatment to the Zr-Al-Beta zeolite in alcoholic solution of alkali metal hydroxide was conducted. The modification of alkali-metal ions on both Lewis acid sites and Brønsted acid sites in Zr-Al-Beta was evidenced by XPS and FT-IR spectroscopy (CO and pyridine). The untreated materials displayed poor product selectivity and high coke deposit in the Meerwein-Ponndorf-Verley reduction of furfural and isopropanol; however, the treatment of alkali-metal ions promoted their catalytic performance with improved recalcitrance to deactivation and coking significantly. Both the type of alkali-metal ions and the concentration of alkaline solution influenced the catalytic performance, which were found to correlate to the acidity and textual properties. The optimum reaction result (97.3% yield of furfuryl alcohol at 99.6% conversion of furfural) can be obtained on 0.025 M-Na+-Zr-Al-Beta with high tolerance to the furfural concentration.

Design &amp; Implementation of an Automated Protective Film Applying Machine for the Aluminum Fabrication

- Aluminum is the third most abundant element in the nature and extrusion is valuable due to commercial fenestration and manufacturing products. Aluminum profiles are causing severe damage during the fabrication and installation process. Sawing, drilling, and tapping are the most common mechanical damages cause in aluminum profiles when subjected to the organic coating. Aluminum is interacting with the Alkali Hydroxides (Ca(OH)2, NaOH, KOH, RbOH, and CsOH) during the cement-based installation process [1]. There are several companies that involving to the manufacturing of aluminum profiles in Sri Lanka. In Sri Lanka, the film applying process of aluminum profiles is carried out by human hand. Due to this problem, companies are looking for solutions to minimize time consumption and cost. The aim of this study is to find a possible solution and design a machine to protect the surface of the aluminum profiles. The objective is to minimize the time consuming and cost-effective method for the film application process. The system was tested with different profile shapes and results were analyzed with the existing manual method. We observed that the designed machine was 87.04% more efficient than the manual existing method in Sri Lanka.

Effect of Alkali Hydroxide on the Properties of PTFE Graphite Bonded Aluminium Titanium Composite Sheet

This study focused on the effect of some alkali hydroxide on the properties of a composite sheet prepared by power spray coating of clean aluminium-titanium sheets with PTFE/graphite emulsion. The blank sheets were washed with hot water and dried at 80 °C for 5-6 minutes before power spraying of colorless polytetrafluoroethylene PTFE/graphite emulsion in perfluoro kerosene followed by hot-rolling under a pressure of 150-200 KPa at the temperature 50 °C higher than the melting temperature of the PTFE polymer (Du Pont). The obtained sandwich was sintered at 550 °C for a few minutes. Alkali hydroxide was added to the polymer emulsion before spraying. Results showed that temperature and time enhanced the extent of adhesion of the two metals to form a homogeneous composite metal sheet. Alkali hydroxide inclusion deteriorates the stability of the prepared sheet. The alkali effect was because PTFE is inactive material, Incompatible with molten alkali metals and alkali hydroxide. The disability of the alkali hydroxide to be incompatible with the polymer material experienced changes in its intrinsic properties. Alkali halides have insignificant effect. Alkali halides just displayed a filling in material.

The Alkali Metal Salts of Methyl Xanthic Acid

Methyl xanthates of the type M(SSC‐OMe) (M = Li–Cs) are readily formed when carbon disulfide is reacted with the corresponding alkali metal hydroxides in methanol exposed to air, or with the alkali metal methoxides in dry methanol or THF under exclusion of air. The reactions are easily monitored by 13C NMR spectroscopy. The Na, K, Rb, and Cs salt could be isolated in high yields, while the Li salt decomposed upon attempted isolation. All compounds are readily complexed by crown ethers and form isolable 1:1 adducts, including the elusive Li salt. All products were studied by NMR (1H, 13C, and alkali metal nuclei) and IR spectroscopy, and most of them where structurally characterized by single‐crystal X‐ray diffraction. Li(SSC‐OMe)(12c4) (12c4 = [12]crown‐4) and Cs(SSC‐OMe)(18c6) (18c6 = [18]crown‐6) represent the first structurally characterized lithium and caesium xanthate complexes, respectively.

Promoting effect of alkali metal cations on the catalytic performance of Pd/H-ZSM-5 in the combustion of lean methane

A series of alkali metal hydroxides (MeOH, Me = Li, Na, K and Cs) were used as the precipitant to prepare the Pd/H-ZSM-5-Me catalysts by deposition-precipitation; the effect of alkali metal cations on the catalytic performance of Pd/H-ZSM-5 in the combustion of lean methane was then investigated. The results indicate that in comparison with ammonia, alkali metal hydroxides as the precipitant can greatly enhance the catalytic performance of Pd/H-ZSM-5 in lean methane combustion and the extent of promoting effect follows the order of CsOH > KOH > NaOH > LiOH >> NH4OH. The alkali metal cations can enhance the dispersion of Pd on the H-ZSM-5 support and effectively reduce the size of Pd particles; in addition, the alkali metal cations may serve as an electron-donating component and endow the Pd species with a unique electronic characteristic, which can promote the activation of C–H bond of methane molecules.