Aqueous Sodium Carbonate Solution Research Articles

Alginic acids in Lessonia vadosa: Partial hydrolysis and elicitor properties of the polymannuronic acid fraction

Extraction of Lessonia vadosa(Laminariales, Phaeophyta) collectedin three different localities near PuntaArenas in the south of Chile, with 3%aqueous sodium carbonate solutions gave asodium alginate yield in the range3.0–17.7% dry weight. There were markeddifferences in the mannuronic acid toguluronic acid ratio (M/G) (0.21–1.69) inthe alginic acids, samples collected inPuerto del Hambre in winter were composedmainly of mannuronic acid residues. Thealginate samples were characterized bypartial hydrolysis and FT-IR spectroscopy.No relationship was found between tissuetype and polyguluronic acid content. Theelicitor activity of the polymannuronicacid enriched fraction from alginic acid ofblades from Puerto del Hambre was assayedin wheat plants. The polymannuronic acidenriched fraction induced substancialelicitation of phenylalanine ammonia-lyase(PAL) and peroxidase (POD) activities.

Preparation and characterization of polyacrylonitrile ultrafiltration membranes

Asymmetric polyacrylonitrile (PAN) ultrafiltration (UF) membranes are prepared from three kinds of coagulant: water, aqueous solution of sodium chloride (NaCl) and aqueous solution of sodium carbonate (Na 2CO 3), using dimethylacetamide (DMAC) as solvent and calcium chloride (CaCl 2) as additive by phase inversion method. The membranes are characterized in terms of the pure water flux, molecular weight cut-off (MWCO) profile and direct field emission scanning electron microscopy (FESEM) observations. The addition of CaCl 2 to the casting solution, up to 3 wt.%, increases the resulting membrane permeability while maintaining their retentive properties. A decrease of the permeability and retention properties is observed when the coagulation bath is aqueous solution of NaCl. Na 2CO 3 in the coagulation bath reacts with CaCl 2 in the casting solution and produces precipitate of CaCO 3. The effect of Na 2CO 3 concentration on the PAN membrane permeability and retention properties is examined. It is found that the pure water fluxes of the PAN membranes increase drastically when the concentration of Na 2CO 3 is high enough.

Process Intensification: Precipitation of Calcium Carbonate Using Narrow Channel Reactors

Precipitation processes are widely used in industry for the production of particulate solids. Efficient mixing of the reagents influences the development of supersaturation in the reaction environment and therefore the particle characteristics. Intensified modules can provide a new route for obtaining improved mixing and this paper illustrates an experimental investigation using narrow channel reactors for the precipitation of calcium carbonate by reacting aqueous solutions of calcium nitrate and sodium carbonate. Two channels of square cross sectional area, having a diagonal line of 1 x 10–3 and 2 x 10–3m, respectively, were used and experiments were carried out by varying flow rates and reagent concentration. A flow visualization technique has been used to understand the flow behaviour in the reactor channels, which were also characterized by calculating the specific power input transmitted to the reagents. The calcium carbonate slurry was analysed for particle size and dispersity with a Malvern Mastersizer 2000. Images of the particles were obtained by using an optical microscope connected to a digital camera and a scanning electron microscope (SEM). Selected samples were also analysed by X-ray diffraction. Limited batch experiments were conducted for benchmarking the performance of the narrow channel reactors.

Solubilities and vapour pressures of saturated aqueous solutions of sodium tetraborate, sodium carbonate, and magnesium sulfate and freezing-temperature lowerings of sodium tetraborate and sodium carbonate solutions

Solubilities and vapour pressures of water over saturated solutions of sodium tetraborate, sodium carbonate, and magnesium sulfate and freezing-temperature lowerings of sodium tetraborate and sodium carbonate solutions were determined and compared with the literature data. These results permitted the evaluation of osmotic and activity coefficients and molar enthalpies of vaporization.

有機めっき処理金属とゴムとの直接架橋接着に関する研究（第４報）有機めっき処理スチールと過酸化物架橋系ＥＰＤＭとの直接架橋接着

It was found recently that ethylene-propylene diene rubber (EPDM) compounded with peroxide could be adhered directly to steel during vulcanization after a polymer plating of steel in 6-diallylamino-1, 3, 5-triazine-2, 4-dithiol monosodium (DAN)/sodium carbonate aqueous solution. The rubber adhesion of the polymer plated steel is studied here with emphasis on the effect of the polymer film thickness and the contents of the compounding ingredients, such as HAF carbon black, process oil and peroxide. In order to evaluate the effect of the compounding ingredients, a three variable central composite designed experiment based on a Box-Wilson response surface methodology is employed. The results show that the thickness of the polymer plating film should be controlled in an optimum range from about 20nm to 200nm in order to obtain enough peel strength of adherend. On the other hand, the peel strength is affected by carbon black, process oil and peroxide contents, and high interactions among these factors are observed. These factors show their respective optimum contents, which is explained as a result of the balance of reactions between peroxide/rubber and peroxide/polymer plating film occurred at the adhesion interface during vulcanization. The adherends under the optimum compounding show excellent heat aging resistance, moisture aging resistance, and water aging resistance.

Oxidative total chlorine free photochemical bleaching of cellulosic fabrics

Water-insoluble natural colored compounds adsorbed or chemically bound on cellulosic fabrics were bleached effectively by a selective photolysis of the colored compounds using various excimer lasers (KrF, XeCl, XeF), a low-pressure mercury lamp, and a black-light fluorescent lamp in the presence of sodium peroxocarbonate or mixtures of sodium carbonate and hydrogen peroxide aqueous solutions at room temperature. The efficiency of the photochemical bleaching was found to be comparable to that of the commercial thermal bleaching processes when a XeF excimer laser or a black-light fluorescent lamp were used as light sources.

Are metastable, precrystallisation, density-fluctuations a universal phenomena?

In-situ observations of crystallisation in minerals and organic polymers have been made by simultaneous, time-resolved small angle X-ray scattering (SAXS) and wide angle X-ray scattering (WAXS) techniques. In isotactic polypropylene slow quiescent crystallisation shows the onset of large scale ordering prior to crystal growth. Rapid crystallisations studied by melt extrusion indicate the development of well resolved oriented SAXS patterns associated with long range order before the development of crystalline peaks in the WAXS region. Block copolymers self-assemble into mesophases in polymer melts above a critical chain length (or above a critical temperature) and this self-assembly process is shown to be susceptible to an incipient crystallisation. Mesophase formation is observed at anomalously high temperatures in ethylene-oxide containing block copolymers below the normal melting point of the polyoxy ethylene chains. Formation of calcium carbonate from aqueous solutions of sodium carbonate and calcium nitrate is observed to be a two-stage process and precipitation proceeds by the production of an amorphous metastable phase. This phase grows until it is volume filling and leads to the formation of the two polymorphs Calcite and Vaterite. These three sets of results suggest pre-nucleation density fluctuations, leading to a metastable phase, play an integral role in all three classes of crystallisation. In due course, this phase undergoes transformation to "normal" crystals.

Heat Capacities of Concentrated Aqueous Solutions of Sodium Sulfate, Sodium Carbonate, and Sodium Hydroxide at 25 °C

Heat capacities of aqueous solutions of Na2SO4 and Na2CO3 up to near saturation (1.9 and 2.5 mol·kg-1, respectively) and of NaOH (to 7 mol·kg-1) have been measured at 25 °C with a Picker flow calorimeter. The calorimeter performance was checked using concentrated NaCl(aq) solutions. On the basis of these measurements, an experimental protocol suitable for the reliable determination of the heat capacities of concentrated electrolyte solutions by Picker calorimetry was established. The heat capacities for Na2SO4(aq), Na2CO3(aq), and NaOH(aq) and literature data for the apparent molar volumes of NaOH(aq) at 25 °C were correlated using the Pitzer formalism. A number of inadequacies in previous models at high concentrations and for extrapolation to infinite dilution are discussed. In particular, it has been confirmed that the heat capacity data for Na2CO3(aq) at low concentrations must be corrected for the hydrolysis of the carbonate ion. Standard partial molar heat capacities for the three salts and the stand...

Removal of H2S to ultra-low concentrations using an asymmetric hollow fibre membrane module

Removal of H2S to ultra-low concentrations using an asymmetric hollow fibre membrane module was studied from gas streams containing 17.9–1159 ppm H2S. The absorption medium used was 2 M sodium carbonate (NaCO3) aqueous solution. A porous polyvinylidene fluoride (PVDF) asymmetric hollow fibre membrane was used as the barrier between the liquid and gas phases. The effect of various operating conditions on H2S outlet concentration and mass transfer coefficient was examined. The operating conditions examined included the feed gas concentration, the gas velocity (resident time), the liquid velocity, and the gas pressure. The PVDF hollow fibre membrane module was found to be very efficient in purification of gas streams containing soluble toxic gases. With the feed concentrations of 17.9–1159 ppm H2S, complete removal of H2S can be reached at very short resistance time (<0.1 s) and low liquid/gas flow ratio. The mass transfer coefficient strongly depends on the gas phase pressure and gas flow rate.

Capillary and Crystalization Strength of Glass Batch Components

The attraction of glass particles simulating quartz sand grains for capillary rings of aqueous solutions of sodium sulfate and carbonate of various concentrations is experimentally investigated. It is shown that the attraction of particles at the first moment of contact with the bridging liquid is determined by the capillary effect. As water evaporates and the solution becomes saturated, additional cohesion of solid particles is registered, which is caused by the formation of crystallization contacts.

Radiolysis of Bicarbonate and Carbonate Aqueous Solutions: Product Analysis and Simulation of Radiolytic Processes

An understanding of the radiation-induced effects in groundwater is essential to evaluate the safe geological disposal of spent fuel. In groundwater, the bicarbonate ion is the predominant and common anion; this work investigated radiation-induced chemical reactions of (bi)carbonate aqueous solutions with steady-state irradiation and pulse radiolysis methods. Aqueous solutions of sodium (bi)carbonate as high as 50 mmol·dm-3 were used. The formation of formate, oxalate, and H2O2 were measured under different conditions. A complete set of reaction steps and reliable kinetic data for the radiolysis of (bi)carbonate aqueous solutions at ionic strength close to the groundwater were proposed. Kinetic calculations were completed based on the proposed reaction steps and the kinetic data obtained in the present work. The results from the calculation are in good agreement with the experimental results. With these proposed reaction steps and kinetic data, computer simulation can be performed to predict the yield of radiolytic products of (bi)carbonate aqueous solutions as a function of irradiation time and used to evaluate the safety of geological disposal options of spent fuel.

Solubility of oxygen in aqueous sodium carbonate solution at pressures up to 10 MPa

The solubilities of oxygen in 0.2, 0.5, 0.7 and 1.0 M Na 2CO 3 solution have been measured at 300.15 K and under pressures up to 10 MPa using a magnetically stirred autoclave and a direct sampling technique. The accuracy of apparatus was verified by duplicating the solubility of oxygen in pure water in literature. The experimental data of the solubility of oxygen in aqueous sodium carbonate solution were shown that the solubility of oxygen increases with increasing pressure and decreases with increasing salt concentration due to salting-out effect. The experimentally measured data were satisfactorily compared with the predicted values by our model based on non-primitive mean spherical approximation (MSA) and perturbation theory.

Electrochemical behaviour of copper–silver alloys in sodium carbonate aqueous solution

The electrochemical behaviour of Cu–20 wt-%Ag and Cu–80 wt-%Ag alloys was studied in aerated Na2 CO3 solutions using cyclic voltammetry, potentiodynamic anodic polarisation, and current transient techniques. The microstructure of the compounds formed on the surface of the alloy during the anodic potential sweep was obtained using XRD analysis. The dissolution behaviour of either of the two constituents from the alloys resembles that of the pure state. The galvanic coupling effect enhances the dissolution of the less noble metal, copper, on alloying with silver. The anodic sweep potential exhibited seven anodic peaks A1 , A2 , A3 , A4 , A5 , A6 , and A7 prior to the oxygen evolution reaction. These peaks are assigned to the formation of Cu2O, Cu(OH)2 , CuO, Ag2O, Ag2 CO3 , and Ag2O2 respectively. Potentiostatic current/time transients showed that the formation of Cu2O, CuO, Ag2O, and Ag2 CO3 layers involves a nucleation and growth mechanism under diffusion control.

Chemical Desulfurization Kinetics of Mengen Lignite in Aqueous Sodium Carbonate

In the present study the effects of sodium carbonate as a leachant in desulfurization of Mengen lignite were investigated. A kinetic study was also carried out, and the shrinking core model was proposed to describe the kinetic data of pyritic sulfur removal. The highest sulfur removal percentages were observed for total and sulfate sulfur as 36.2% and 97.1%, respectively, with the use of a coal alkali solution volume ratio of 1/70 at 120 degrees C. Desulfurization of Mengen lignite with 100 mL of 0.2 M aqueous sodium carbonate solution at 140 degrees C for 3 hours caused 96% removal of pyritic sulfur. It was also observed that the rate of leaching increased significantly with temperature and alkali solution concentration.

On triazoles. XL [1]. Non catalytic dehalogenation of some 5‐chloro‐1,2,4‐triazolo[1,5‐a]pyrimidine derivatives

AbstractA non catalytic dehalogenation method of type 4 5‐chloro‐1,2,4‐triazolo[1,5‐a]pyrimidine derivatives based on the hydrolysis of the corresponding type 5 p‐toluenesulphonyl hydrazones with diluted aqueous sodium carbonate solution was elaborated. The method provides the required 5‐unsubstituted derivatives 6 also in those cases when the simple hydrogenation is not possible. Using deuterium oxide as the solvent of the hydrolysis, deuterium atoms also could be inserted into position 5 of derivatives 6. Different by‐products of the reactions were also isolated, and a possible explanation was given for their formation.

Dielectric relaxation of aqueous Na2CO3 solutions

The complex dielectric permittivity of aqueous sodium carbonate solutions (0.05⩽c/mol L-1⩽2.5) has been determined in the frequency range 0.2⩽ν/GHz⩽20 at 25.0°C with a commercial dielectric measurement system based on a vector network analyser. A superposition of three Debye relaxation processes was necessary to fit the complex permittivity spectra. The slow and intermediate dispersion steps are assigned to double solvent separated (2SIP) and solvent-shared (SSIP) NaCO3-(aq) ion-pairs respectively. The absence of contact ion-pairs was confirmed by Raman spectroscopy. The fast process is assigned to the collective relaxation of the solvent. Equilibrium constants for the formation of NaCO3-(aq) were determined from the ion-pair dispersion amplitudes. The effect of Na2CO3 concentration on the water dispersion amplitude allowed effective solvation numbers to be deduced.

Densities of aqueous solutions of sodium carbonate and sodium bicarbonate at temperatures from (298 to 623) K and pressures to 28 MPa

Densities of aqueous solutions of Na2CO3and NaHCO3with molalities from 0.1 mol·kg−1to 1.0 mol·kg−1have been measured from the temperatures 298 K to 623 K and pressures up to 28 MPa using a vibrating-tube flow densimeter. The volumetric results for Na2CO3(aq) and NaHCO3(aq) are in good agreement with the literature data at low temperatures. At high temperatures, the treatment of results must include the hydrolysis of Na2CO3(aq), disproportionation of NaHCO3(aq), and association of carbonate and bicarbonate ions with sodium ion.

Partially carboxymethylated novolaks for photoresist systems: New photoresists for development under mildly alkaline conditions

The dissolution behaviour of cresolic novolaks in alkaline developers has been modulated by a modification reaction with chloroacetic acid (‘carboxymethylation’). This reaction effected a partial etherification of the phenolic OH-groups. The desired solubility has been adjusted by the degree of conversion in combination with the choice of an appropriate parent novolak. The influence of the carboxymethylation on the dissolution rates of the resins turned out to be strongly dependent on type and concentration of the developer. Moreover, different dissolution kinetics have been observed in TMAH and sodium carbonate solution. The lithographic properties of selected carboxymethylated novolaks have been investigated. Photoresists have been optimised with respect to environmental and safety aspects (‘safer solvents’, development in aqueous sodium carbonate solution). The formulation of negative resists has been complicated by an unexpected incompatibility of the resin and the photoactive compound. However, first results of positive resist formulations were promising. Resolutions down to 1 μm 1&s have been achieved.

Zeolite materials with enhanced ion exchange capacity

In accordance with the present invention, there are now provided zeolite materials with enhanced ion exchange capacity, which are obtained by treating ZSM-5, Y and X zeolites with aqueous solutions of sodium carbonate and sodium hydroxide. With such a treatment, some silicon species are selectively removed from the zeolite frameworks, thus increasing the density of the tetrahedral Al sites. The invention concerns also the use of the thus obtained zeolites for the removal of Ca and Mg ions from hard waters.

稲わらの直接液化

The liquefaction of powdered rice straw, suspended in an aqueous solution of sodium carbonate or potassium carbonate as a catalyst, was examined at temperatures ranging from 250 to 376°C, and with reaction times 0, 30 and 60 min. by using a convenient small-sized tubing-bomb as a reactor. Separation procedure of the reaction mixtures is demonstrated in Fig. 1.The effect of reaction temperature on the yield of products, using sodium carbonate, is shown with different reaction times in Fig. 2. The oleaginous substance O-1 and O-2 are the major parts of the liquefaction products. The whole oily products, the sum of O-1, O-2, O-3 and O-4, increase with the rise in temperature until 350°C, ranging from 6% (250°C, 0min.) to 27% (350°C, 60min.) of the original weight of rice straw, while the case at 376°C, a super-critical temperature of water, is exceptional.Similarly, the temperature-dependence of the yield of products, using potassium carbonate, is shown in Fig. 3, with different reaction times. The yield of main oily product O -1 increases with the rise in reaction temperature. Potassium carbonate is slightly better than sodium carbonate as a catalyst.(Fig. 4)The effect of addition of organic solvent, e. g. acetone, on the yield of main oily product O-1 is shown in Fig. 5.The yields, elementary compositions and heating values of oily products O-1 and O -2, which obtained under various reaction conditions, are listed in Table 1.