Amount Of K2CO3 Research Articles

Mathematical Modelling and Optimization for Facile Synthesis of Structured Activated Carbon (ACs) from Adansonia kilima (Baobab) Wood Chips Integrating Microwave-Assisted Pyrolysis for the Elimination of Lead (II) Cations from Wastewater Effluents.

In this research, activated carbon (AC) was synthesized from ligno-cellulosic residues of Adansonia kilima (Baobab) wood chips (AKTW) using two-step semi-carbonization and subsequent pyrolysis using microwave-induced heating (MWP) in the presence of a mild activating agent of K2CO3. The influence of process input variables of microwave power (x1), residence time (y1), and amount of K2CO3 (z1) were analysed to yield superior quality carbon having maximum removal efficiencies (R1) for lead (II) cations from waste effluents, fixed carbon percentages (R2), and carbon yield percentages (R3). Analysis of variance (ANOVA) was used to develop relevant mathematical models, with an appropriate statistical assessment of errors. Level factorial response surface methodology (RSM) relying on the Box-Behnken design (BBD) was implemented for the experimental design. The surface area and porous texture of the samples were determined using Brunauer, Emmett, and Teller (BET) adsorption/desorption curves based on the N2 isotherm. Surface morphological structure was observed using field emission scanning electron microscopic (FESEM) analysis. Thermogravimetric analysis (TGA) was carried out to observe the thermal stability of the sample. Change in the carbon content of the samples was determined using ultimate analysis. X-ray diffraction (XRD) analysis was performed to observe the crystalline and amorphous texture of the samples. The retention of a higher proportion of fixed carbon (80.01%) ensures that the synthesized adsorbent (AKTWAC) will have a greater adsorption capacity while avoiding unwanted catalytic activity for our synthesized final sample.

Synthesis, characterization and antioxidant activity of 2-(4-Phenyl-6-p-Tolylpyrimidin-2-ylthio)-N-(4-substituted Phenyl)acetamides

A series of 2-(4-phenyl-6-p-tolylpyrimidin-2-ylthio)-N- (4-substituted phenyl)acetamide(4a-o) has been synthesized. Compounds have been characterized and tested for their antioxidant activity. The titled compounds (4a-o) have been synthesized by the reaction between 4-phenyl-6-p-tolylpyrimidine-2-thiol (2) with 2-chloro-N-substituted phenylacetamide (3ao) refluxed in acetone using catalytic amount of K2CO3. Compound (2) has been synthesized from (E)-1-phenyl- 3-p-tolylprop-2-en-1-one (1) with equimolar amount thiourea refluxed in alcoholic KOH to get compound (2). Starting compound chalcone was synthesized by Claisen-Schmidt condensation. All synthesized compounds have been characterized using spectroscopic techniques such as FT-IR, 1H NMR, 13C NMR, Mass Spectrometry and elemental analysis. Antioxidant assay has been performed by using DPPH radical scavenging method. Compounds 4-h and 4-o have shown good antioxidant activity.

Solid Electrolyte Interphase and Nitrogen Doping Effect on Potassium Storage Mechanism in Graphite

The inferior cycling stability critically impedes the development of potassium-ion batteries (KIBs). The solid electrolyte interface (SEI) for nitrogen doped graphite foam (NGF) was studied in both KPF6 and KN(SO2F)2 (KFSI)-based organic electrolytes, aiming to unravel the SEI effect on K+ ion storage mechanism. Electrochemical characterizations disclose that the KN(SO2F)2-based cells deliver improved electrochemical performance in terms of reversibility and cycling stability, compared to KPF6 based cells. Experimental results including depth-profiling XPS and FTIR spectra, together with the theoretical calculations, reveal that (CH2OCO2K)2, C2H5OCO2K, KF and K2CO3 are the dominant components of SEI layers in both electrolytes. Particularly, the amount of K2CO3 in KPF6-based electrolyte is much more than that in KFSI-based electrolyte, resulting in inferior stability. Moreover, the depth-profile XPS results indicate that the SEI formed in KFSI based electrolyte is much more stable, compact and thinner than that in KPF6 based electrolyte. All these features, together, ensure good stability and high reversibility in KFSI-based electrolyte. The nitrogen doping effect on K+ ion storage was also explored. Enhanced electrochemical performance was identified upon increasing the nitrogen content, due to i) the enrichment of active sites for K+ ion storage and ii) the improved electronic conductivity. Moreover, the electrochemical performance is strongly dependent on N-doping types. Specifically, the pyridinic nitrogen dominates the reversible capacity, as identified by the presence of critical point at 4.29 at. %. In which, the atomic ratio of pyridinic N in NGF is 2.53 at. %, which is higher than that of 7.03 at. %, with only 2.16 at. % pyridinic N. The result is consistent with the theoretical study, which verifies that the charge transferred from K ions to NGF increases with the pyridinic nitrogen doping. Our results promote better understanding of K+ ion storage mechanism in graphite and provide invaluable guidance for optimized carbon-based electrode design for high-performance KIBs.

Electrochemical stability and cell response of nanostructures elaborated on zirconium

The paper studies the electrochemical stability in physiological serum and cell response of nanostrucures obtained on Zr by anodizing in electrolytes containing fluorinated ethylene glycol and various amounts of K2CO3. SEM analysis revealed that the porous nanostructure formation is greatly influenced by the various K2CO3 concentrations in the electrolyte by tipping the balance between oxide formation and dissolution during the anodizing process. The porosities of the samples were evaluated from polarization resistances recorded in physiological serum. Chronoamperometric measurements were employed to establish a range of compactness for the samples. It was found that the amount of K2CO3 from the electrolyte is directly responsible in obtaining oxide strata more resistant to corrosion. All tests performed on the samples such as corrosion, hydrophylicity and cell viability with MC3T3‐E1 pre‐osteoblasts cells from mouse bones revealed that the best coating for future research regarding nanostructured Zr implants was the one obtained from the electrolyte containing the highest amount of K2CO3.

Factors for the synthesis of 18F-MyoZone and myocardial tomography in normal swine

Objective To study the factors affecting the synthesis of 18F-MyoZone, and to evaluate its potential as a myocardial perfusion imaging (MPI) agent in normal Chinese mini-swine. Methods 18F-MyoZone was prepared by substituting the leaving group toluenesulfonyloxy (OTs) from the precursor compound with 18F-fluoride (18F-F-). The conditions affecting the labeling yield were studied by varying the amount of K2CO3 and precursor compound, 18F-fluorination reaction time and temperature. PET was performed at 5, 30, 60 and 120 min post-injection on normal Chinese mini-swine. Results The doses of K2CO3 and precursor, the reaction time and the reaction temperature could affect the labeling yield of 18F-MyoZone, especially K2CO3. The optimized synthetic condition was 1.0 mg K2CO3,2.0 mg mpp2-OTs, 20 min reaction time at 90 ℃. The total radio-synthesis time in this condition was 60 min. The uncorrected radiochemical yield was (24.0±5.1)%. The radiochemical purity was >98%. PET imaging showed that 18F-MyoZone had high initial uptake (SUV=8.17±1.83 at 5 min post-injection) and good retention (SUV=5.78±0.99 at 120 min post-injection) in the heart. The clearance of 18F-MyoZone from liver was very fast. The heart/liver ratios were 3.32, 5.31, 6.09 and 5.76 at 5, 30, 60 and 120 min post-injection, respectively. From 5 to 120 min post-injection, the outline of heart was clear and intact. There was almost no interference from the adjacent organs. The quality of PET images was highly satisfactory. Conclusions 18F-MyoZone has the potential to be a good myocardial perfusion agent. The amount of K2CO3 used could significantly affect the labeling yield of 18F-MyoZone. Key words: MyoZone; Fluorine radioisotopes; Isotope labeling; Myocardial perfusion imaging; Positron-emission tomography; Tomography, X-ray computed; Swine

One-pot efficient pseudo-five-components synthesis of 4,4′-(arylmethylene)bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) at room temperature assisted by K2CO3

ABSTRACTA convenient approach for the synthesis of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ols) by an efficient one-pot reaction of aromatic aldehydes, phenylhydrazine, and ethyl acetoacetate by using substoichiometric amount of K2CO3 in acetonitrile solvent at room temperature is described. This protocol of one-pot synthesis produced a library of bis-pyrazolylmethane derivatives, a potential bioactive compound in very good to excellent yields.

Carbon Dioxide Absorption Behavior and Carbonate Ion Transport of Lithium Orthosilicate / Potassium Carbonate Coexistence System Prepared By Ball Milling

Lithium Orthosilicate (Li4SiO4), a type of ceramic CO2 absorbent has a large absorptive capacity (36.7 wt. %) and also has heat resistance. This material has some useful application as a separator in Molten Carbonate Fuel Cell and as a direct CO2 absorbent in large-scale emission sources, for example, thermal power stations; because the following equilibrium reaction at the temperature around 993 K; Li4SiO4 + CO2 ⇄ Li2CO3 + Li2SiO3. In this study, we focused on the absorption behaviors of CO2 at lower temperature into Li4SiO4 in combination of these two methods and evaluated the physiochemical dependence of surface properties of CO2 absorption reaction. Li4SiO4 was prepared from solid state reaction. SiO2 powder and Li2CO3 powder were mixed at the molar ratio Li/Si = 4.0. The mixture was calcined at 973 K for 20 h in air. The resulting powder (Li4SiO4) kept in an Argon atmosphere glove box and in order to confirm the effect of carbonate, was mixed with a given amount of K2CO3. Each mixture (2.5 g) was put in the grinding bowl with the grinding balls, it sealed up under the Ar atmosphere, and the grinding processing was done for 0-300 minutes in revolution speed 250 rpm using planetary ball mill. Also, the grinding process was done under the condition of one cycle for 15 minutes of the grinding processing and two minutes of rest time to prevent the samples temperature from rising. Samples were characterized with X-ray diffraction (XRD), N2-isotherm, SEM, SEM-EDX, TG-DTA and Electro spin resonance (ESR). It was found that samples whose surface was modified with ball milling method under Ar gas flow showed a tendency to increase the surface area estimated by BET method measured by N2-isotherm and increase of Si dangling bond measured by ESR. Also, it was found that there are two different absorption processes, one is a chemisorption at the surface (T<773 K) the other is a bulk diffusion (T>773 K) by the result of TG-DTA. As seen in isothermal analysis (Fig. 1), the CO2 absorb reaction rate improved by the coexistence of K2CO3 infiltrated in Li4SiO4 being promoted by not only the surface area was increased and activated by the ball milling but also absorbing CO2 of coexisting K2CO3. Furthermore, it was found that ΔG‡ decreased from the result of the isothermal analysis at 873 K. We would like to consider controlling transportation of carbonate ion electrochemically according to the CO2 absorption reaction as a separator in Molten Carbonate Fuel Cell. Figure 1

Suzuki–Miyaura cross-coupling reaction between aryl halides and phenylboronic acids over gold nano-particles supported on MgO (or CaO) and other metal oxides

Gold nano-particles-supported alkaline earth metal oxides, particularly MgO or CaO, show high catalytic activity in the Suzuki–Miyaura cross-coupling reaction in the presence of K2CO3 and DMF (as a solvent). The catalytic activity is strongly influenced by the nature or type of metal oxide support (viz. alkaline earth oxide, Group IIIA metal oxide, transition metal oxide, or rare earth oxide actinide oxide). It is also strongly influenced by the nature of aryl halide (aryl iodide, bromide, chloride, or fluoride), amount of K2CO3 in the reaction mixture and catalyst calcination temperature. Influence of reaction parameters viz. temperature and time and different substituents in aryl halides and/or phenylboronic acids on the biphenyl product yield in the reaction over Au/MgO catalyst has also been investigated. The catalyst showed excellent reusability in the reaction. Moreover, it is ligand-free and also has much lower cost than the commonly used homogeneous and heterogeneous Pd catalysts.

Synthesis of Biodiesel by Phase Transfer Catalysis

Biodiesel was synthesized starting soybean oil and methanol using K2CO3 and phase-transfer catalysis TBAB. It was studied that the yield of biodiesel can be changed with reaction factors such as the kind and the amount of phase-transfer catalysis, the amount of K2CO3, reaction time, molar ratio between methanol and soybean oil, reaction temperature. The results show that the reaction conditions are as following: mass ratio of TBAB to soybean oil weight 0.6%, mass ratio of K2CO3 to soybean oil weight 1.5%, molar ratio between methanol and soybean oil 6∶1, reaction time 20 min, reaction temperature 40 °C. The yield of biodiesel reached 95% under the optimum reaction conditions.

Regioselective Direct Carboxylation of 2-Naphthol with Supercritical CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; in the Presence of K&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;CO&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;

A direct regioselective preparation of 2-hydroxynaphthalene-6-carboxylic acid, a useful industrial intermediate of aro-matic polyester from 2-naphthol was conducted by use of excess amount of K2CO3 (10-fold molar to 2-naphthol) under supercritical CO2 at 10 MPa and 473 K. The obtained yield under this condition was ca. 20 mol% to 2-naphthol. The further investigations may provide an alternative process to the conventional Kolbe-Schmitt reaction, because of no use of strong alkali and recoverability of K2CO3. Theoretical explanation about the regioselectivity was achieved by means of DFT calculations.

Mineralizer Mediated Self-Assembly of PbTiO&lt;sub&gt;3&lt;/sub&gt; Crystals

PbTiO3 crystals with different morphologies, such as flower-like and spherical shape, which was constructed by oriented nanoparticles have been obtained by a simple surfactant-free hydrothermal process assisted by K2CO3 as a mineralizer. Powder X-ray diffraction (XRD) analysis was applied to examine the purity and crystallinity of the as-prepared samples. The morphologies have been characterized by scanning electron microscopy (SEM). The results indicated that the self-assembly structures of PbTiO3 crystals were dependent on the addition amount of K2CO3 and the formation mechanism of the products was briefly discussed.

MORPHOLOGICALLY CONTROLLED SYNTHESIS OF Au NANOCRYSTALS

In this work, a convenient and efficient procedure to control the morphologies of Au nanocrystals has been reported. The Au nanospheres are generated in polyvinyl-pyrrolidone/ethanol glycol system through a thermal chemical method. However, by adding a small amount of K2CO3 which influences the growth rate of various facets during the crystal growth, Au nanoplates with broad surface plasmon resonance band in 500–800 nm can be obtained.

Base-Catalyzed Conjugate Addition of Thiols to Indolyl Acrylic Acids and in situ Decarboxylation: An Expedient Synthesis of Functionalized 3-(1-Thio)ethyl-1H-indoles

A one-pot, two-step method for the synthesis of 3-(1- thio)ethyl-1H-indoles is described herein. This simple procedure in- volves the Michael addition of thiols to 3-indoleacrylic acids fol- lowed by in situ decarboxylation of the Michael adduct in the presence of a catalytic amount of K2CO3 in DMF at 100 °C. The method was found to be fairly general with various thiols and dif- ferent 3-indoleacrylic acids.

Rapid determination of bisphenol A in drinking water using dispersive liquid‐phase microextraction with in situ derivatization prior to GC‐MS

This paper described a novel approach for the determination of bisphenol A by dispersive liquid-phase microextraction with in situ acetylation prior to GC-MS. In this derivatization/extraction method, 500 microL acetone (disperser solvent) containing 30.0 microL chlorobenzene (extraction solvent) and 30.0 microL acetic anhydride (derivatization reagent) was rapidly injected into 5.00 mL aqueous sample containing bisphenol A and K2CO3 (0.5% w/v). Within a few seconds the analyte was derivatized and extracted at the same time. After centrifugation, 1.0 microL of sedimented phase containing enriched analyte was determined by GC-MS. Some important parameters, such as type and volume of extraction and disperser solvent, volume of acetic anhydride, derivatization and extraction time, amount of K2CO3, and salt addition were studied and optimized. Under the optimum conditions, the LOD and the LOQ were 0.01, 0.1 microg/L, respectively. The experimental results indicated that there was linearity over the range 0.1-50 microg/L with coefficient of correlation 0.9997, and good reproducibility with RSD 3.8% (n = 5). The proposed method has been applied for the analysis of drinking water samples, and satisfactory results were achieved.

Applying an Aza-Wittig Reaction for the Synthesis of Novel Thieno[3′,2′:5,6] Pyrido[4,3-d]pyrimidinone Derivatives

A series of new 2-substituted tetrahydrobenzo[4′,5′]thieno[3′,2′:5,6]pyrido[4,3-d] pyrimidin-4(3H)-ones 5 has been designed and synthesized via an aza-Wittig reaction. Iminophosphorane 3a or iminophosphorane 3b reacted with 4-Cl-phenyl(or 4-F-phenyl) isocyanate to give carbodiimide 4a or carbodiimide 4b , which were further treated with phenols to cyclize to give compounds 5 in presence of a catalytic amount of K2CO3. The structures of compound 5 have been confirmed by 1H NMR, EI-MS, IR spectroscopy, and elemental analyses.

Effect of Catalyst on Yield of Liquid Products from Biomass via Pyrolysis

The pyrolysis of biomass is a thermal treatment that results in the production of charcoal, liquid, and gaseous products. Among the liquid products, methanol is one of the most valuable products. Methanol can be used as one possible gasoline replacement for conventional gasoline and diesel fuel. Methanol can be produced by pyrolysis of biomass. Methanol mainly arises from methoxyl groups of uronic acid and from the breakdown of methyl esters and/or ethers from decomposition of pectin-like plant materials. The maximum methanol yields (12.19% at 825 K) for hazelnut shell was obtained from a Na2CO3 (30% of dried sample) catalytic flash pyrolysis run. The yields of liquid products from the samples increased with an increasing of the amount of Na2CO3 from 10% to 30%. The maximum liquid yield from yellow pine was 51.2% at 875 K. The yields of liquid products from the samples depended on the amount of K2CO3 and the temperature. The maximum liquid yield from yellow pine was 49.5% from a 30% K2CO3 catalytic run at 875 K. The catalytic effect of Na2CO3 was slightly higher than that of K2CO3 for hazelnut shell, tea waste, and yellow pine samples.

Effect of Catalyst on Yield of Liquid Products from Biomass via Pyrolysis

The pyrolysis of biomass is a thermal treatment that results in the production of charcoal, liquid, and gaseous products. Among the liquid products, methanol is one of the most valuable products. Methanol can be used as one possible gasoline replacement for conventional gasoline and diesel fuel. Methanol can be produced by pyrolysis of biomass. Methanol mainly arises from methoxyl groups of uronic acid and from the breakdown of methyl esters and/or ethers from decomposition of pectin-like plant materials. The maximum methanol yields (12.19% at 825 K) for hazelnut shell was obtained from a Na2CO3 (30% of dried sample) catalytic flash pyrolysis run. The yields of liquid products from the samples increased with an increasing of the amount of Na2CO3 from 10% to 30%. The maximum liquid yield from yellow pine was 51.2% at 875 K. The yields of liquid products from the samples depended on the amount of K2CO3 and the temperature. The maximum liquid yield from yellow pine was 49.5% from a 30% K2CO3 catalytic run at 875 K. The catalytic effect of Na2CO3 was slightly higher than that of K2CO3 for hazelnut shell, tea waste, and yellow pine samples.

Evaluation of CSC Charcoal for Production of Dry Combustion Plasma

Evaluation of CSC charcoal by standard thermoanalytical techniques shows that the dry material contains ⪞ 99% carbon having calorific value of about 16.32 mJ/kg; its hydrogen and ash contents are insignificant. On admixture with small amount of K2CO3 (seed for generation of combustion plasma) its combustion characteristics remain more or less unaltered though the combustion rates are greatly enhanced.

クロムメッキ液中のSiF&lt;sub&gt;6&lt;/sub&gt;の自動制御

The self-regulation of fluorosilicate concentration by the addition of K+ to a chromium plating bath saturated with K2SiF6 was studied. The following results were obtained: (1) Since K2SiF6 is a strong acid salt, the solubility of K2SiF6 in low pH solution such as a chromium plating bath was not much higher than that in its aqueous solution. (2) The decrease in the solubility of K2SiF6 conforming to “common-ion effect” did not agree to the following dissociation. K2-SiF6→2K++SiF62-. (3) The reason was explained by the following hydrolysis of K2SiF6: K2SiF6+H2O→2K++SiF5(OH)2-+HF. The dissociation of a fluorosilicate having higher solubility such as Na2Si F6 was as follows: Na2SiF6→2Na++SiF62-. Whereas, the dissociation of a fluorosilicate having lower solubility such as BaSiF6 was as follows: BaSiF6+2H2O→Ba2++SiF4(OH)22-+2HF. The results of experiments well agreed with the basis of these dissociations. (4) For example, the solubility of K2SiF6 was 10g/l in chromium plating bath containing 250g/l of CrO3 at 55°C. Therefore, the plating bath for selfregulating SiF6 was prepared by the addition of a small amount of K2CO3 to the bath. The solubility of K2SiF6 was 7g/l in low concentration chromium plating bath containing 50g/l of CrO3 at 55°C. Since the optimum concentration of K2SiF6 in this bath is 0.6g/l, 27.5g/l of K2CO3 shall be added to get the self-regulating bath. However, this composition was not adequate for the chromium plating bath owing to the increase of pH value.