Adding Sodium Carbonate Research Articles

Pellet reactor pretreatment: A feasible method to reduce scaling in bipolar membrane electrodialysis

This study aims to evaluate the feasibility of a pellet reactor in reducing the scaling potential in electrodialysis with bipolar membranes for water containing a high concentration of calcium by adding sodium carbonate to precipitate carbonate as calcium carbonate on granular seed material. The optimized operating condition obtained at pH 11.1, and a ratio of [CO32-]:[Ca2+]=1.2:1 enabled to obtain 90% efficiency of calcium removal from real water. The efficiency of scaling potential removal was validated by comparing the scaling level on the membrane surface of two electrodialysis batches of a washing water, with and without pretreatment. For the latter, scalants were found at both sides of the cation exchange membrane (FKB), diluate and base sides, identified as calcium and magnesium precipitates. Furthermore, there was also a severe scaling effect at the base side of the bipolar membrane (FBM). However, a different observation was found for the pretreated water. SEM and elemental analysis for both FKB and FBM membranes demonstrated less scaling on both membrane surfaces.

Investigations on a Novel Process to Recycle Valuable Metals from Spent Al<sub>2</sub>O<sub>3</sub>-Based Catalyst

Based on X-ray phase analysis and exploratory experiments, a novel process was proposed to recycle multiple valuable metals like Al, V, Mo, Ni and Co from spent Al2O3-based catalyst. The spent catalyst was roasted by adding sodium carbonate with certain mol ratio, after water leaching, Al, V and Mo could be extracted into leach liquor, whereas Ni and Co were enriched in the leaching residue. V and Mo were precipitated in step from leach liquor by adding CaO and BaAl2O4, respectively. After removal of V and Mo, Al(OH)3 was prepared from sodium aluminate solution with carbonation decomposition process, and the purity of Al2O3 is 99.98%. With sodium bicarbonate leaching-purification-precipitation-calcination process, V2O5 could be prepared from V-bearing residue. Ni and Co were leached from water leaching residue with sulfuric acid. Recoveries of Al, V, Mo, Ni and Co from spent catalyst are 87.0%, 88.7%, 92.1%, 97.8% and 98.6%, respectively.

Research Progress in Formation Mechanism of TiO<sub>2</sub> Nanotubes and Nanopores in Porous Anodic Oxide

Self-ordered porous anodic TiO2 nanotubes and other porous anodic oxides (PAO) have received considerable attention because of their potential for high technological application in a number of fields. The anodization of valve metals has been widely investigated over the last eight decades. The formation mechanisms of hexagonal cells and nanotubes, however, have remained unclear until now. Simply reviewing the mechanisms of PAO formation was not the aim of this research and we were more interested in reviewing the forming processes of compact anodic oxides (CAO) and investigating the relationship between the PAO and CAO, to better understand the pore generating mechanisms. The present work introduces the differences between PAO and CAO films, as well as reviewing the traditional theories of PAO films and their deficiencies. Recent progress in the formation mechanism of PAO, including the viscous flow, breakdown, equifield strength, and oxygen bubbles models has been reviewed in detail. The perspective on future developments for the PAO forming mechanism has been tentatively discussed. Based on sufficient analysis of the latest findings, it has been proposed that several approaches may be employed for investigating the pore forming and self-ordering mechanisms. These new approaches include ultrasound-assisted anodizing, anodizing under vacuum or high pressure and adding sodium carbonate or a reducing agent to the PAO-forming electrolytes. An investigation of changes in the current and anodizing efficiencies would also be an effective approach for better understanding the physical nature of field-assisted dissolution (FAD).

Catalyzing Carbothermic Reduction of Siderite Ore with High Content of Phosphorus by Adding Sodium Carbonate

The characteristics of Huimin siderite ore with high content of phosphorus and the reduction of this ore bearing pulverized coal and sodium carbonate were investigated. The study focuses on the influence of Na2CO3 dosage on the carbothermic reduction process. Iron particle size in reduced ore is tiny and the fayalite is abundant without Na2CO3 additive. With ratio of Na2CO3 to ore at 1:20 or 1:10, iron particle size in reduced ore is coarse and the diffraction intensity of metallic iron increases obviously in the XRD pattern. The reduction of siderite can be catalyzed by adding an appropriate amount of Na2CO3. The catalyzing activity may be caused by the increase of the reducing reaction activity of FeO and the acceleration of the carbon gasification reaction rate. The phosphorus compounds were not reduced in the low temperature reduction process and remained as fluorapatite in the gangue phases. Ultrafine grinding-magnetic separating of magnetic minerals is an efficient way to obtain qualified iron concentrate.

Characteristics of sodium compounds on NO reduction at high temperature in NO x control technologies

Characteristics of sodium compounds additives on NO reduction at high temperature were investigated in a tube stove and a drop tube furnace. Sodium carbonate, sodium hydroxide and sodium acetate were chosen as Na additives to research the effect on NO reduction. It was found that sodium compounds could reduce NO emission and promoted NO reduction efficiency during pulverized coal combustion, coal reburning and urea-SNCR process. Adding sodium carbonate into crude coal gained 3.2%–34.8% of NO reduction efficiency on different combustion conditions during the coal combustion process. NO reduction efficiency was affected by sodium content and coal rank. Na additive performed NO reduction effect in whole Shenhua coal combustion process and in char rear combustion of Gelingping coal. Adding sodium hydroxide into the reburning coal increased NO reduction efficiency of the reburning technology. NO reduction efficiency was increased to 82.7% from 50.0% when the weight ratio sodium to the reburning coal was 3% and the ratio of the supplied air to the theoretical air of reburning fuel was 0.6. Sodium carbonate, sodium hydroxide and sodium acetate performed the promotion of NO reduction efficiency in urea-SNCR. Sodium acetate promoted NO reduction efficiency best while sodium hydroxide promoted worst at 800 °C. Sodium additives as SNCR promoter performed much better at lower temperature than at higher temperature, and they promoted NO reduction weakly in urea-SNCR when the temperature was greater than 900 °C.

Study on the influence of additives in an industrial calcium fluoride and waterworks sludge co-melting system

This work explores the effect of additives on the pouring temperature in a waterworks and industrial calcium fluoride sludge co-melting system. Two kinds of sludge were mixed in various ratios to find a mixing ratio at which the operating temperature for subsequent additive tests was relatively low. Various proportions of either sodium carbonate (Na 2CO 3) or potassium carbonate (K 2CO 3) reagent were added to the mixed-sludge samples to elucidate the consequent changes in pouring temperature. The experimental results revealed that the pouring temperature was lowest when calcium fluoride was mixed with waterworks sludge in a ratio of 4:6 (w/w). Adding sodium carbonate or potassium carbonate reagent to the mixed-sludge samples further reduced the pouring temperature. Increasing the amount of sodium carbonate did not significantly reduce the pouring temperature beyond that observed when 2% was added, suggesting that 2% was the optimal additional percentage of sodium carbonate. In contrast, the pouring temperature was increased when over 2% potassium carbonate was added to the mixed-sludge samples, revealing that the optimal additional percentage of potassium carbonate was also 2%. These findings indicate that both sodium carbonate and potassium carbonate can be used as additives to increase the energy efficiency of the melting process, but sodium carbonate is more operationally convenient.

Catalytic growth of carbon nanotubes with large inner diameters

Carbon nanotubes (2.4 g/g catalyst), with large inner diameters were successfully synthesized through pyrolysis of methane on a Ni-Cu-Al catalyst by adding sodium carbonate into the carbon nanotubes growth system. The inner diameter of the carbon nanotubes prepared by this method is about 20-60 nm, while their outer diameter is about 40-80 nm. Transmission electron microscopy and X-ray diffraction were employed to investigate the morphology and microstructures of the carbon nanotubes. The analyses showed that these carbon nanotubes have large inner diameters and good graphitization. The addition of sodium carbonate into the reaction system brings about a slight decrease in the methane conversion and the yield of carbon. The experimental results showed that sodium carbonate is a mildly toxic material which influenced the catalytic activity of the Ni-Cu-Al catalyst and resulted in the formation of carbon nanotubes with large inner diameters. The growth mechanism of the carbon nanotubes with large inner diameters is discussed in this paper.

Delamination and restacking of a layered double hydroxide with nitrate as counter anion

A layered double hydroxide (LDH) with nitrate as the counter anion (LDH–NO3 with Mg/Al = 3) was, for the first time, successfully delaminated in formamide under ultrasonic treatment. Atomic force microscopy (AFM) images showed that a large part of the LDH was delaminated into single and double brucite layers (0.7–1.4 nm in thickness). The nano-sheets had disk-like shapes with a diameter of ca. 20–40 nm. Findings from AFM were in good agreement with the average hydrodynamic diameter determined using dynamic light scattering. Powder X-ray diffraction pattern of LDH dispersed in formamide also confirmed that LDH–NO3 was exfoliated. The dispersions of LDH in formamide were stable and transparent up to a concentration of 40 g L−1. However, formation of transparent gels was observed at concentrations higher than 5 g L−1. Delaminated LDH could be restacked by adding sodium carbonate or ethanol.

Using carbonate fluxes to remove oxygen and sulfur from blister copper

A new method for simultaneously removing oxygen and sulfur from blister copper by adding sodium carbonate is described in this article. The main factors influencing the thermodynamics of the reaction, such as temperature, composition of the blister copper, and carbonate/sulfate salt ratio are presented with the help of phase diagrams. The results of preliminary experiments are very encouraging as copper containing 2–145 ppm sulfur and 1,100–3,700 ppm oxygen was produced without the use of a conventional hydrocarbon-reduction stage.

HYDROLYSIS OF ETHYL-2-BROMOISOBUTYRATE ESTER IN AN ALKALINE SOLUTION

The hydrolysis of ethyl-2-bromoisobutyrate in an alkaline solution/organic solvent two-phase medium as well as the effect of quaternary ammonium salt (e.g., tetrabutylammonium bromide) on the hydrolysis of ethyl-2-bromoisobutyrate were investigated in this work. The proposed mechanism for the hydrolysis of ethyl-2-bromoisobutyrate was verified based on experimental analysis. Both the bromo-alkyl (Br-C bond) and ester (-COOR) functional groups of ethyl-2-bromo-isobutyrate hydrolyze into alcohol and acid. Several reaction steps for the hydrolysis of these bromo-alkyl and ester functional groups were developed and discussed. A kinetic model of each reaction step was developed in which the rate expression was derived. The intrinsic rate constants of the reactions were determined from the experimental hydrolyzing data of ethyl-2-bromoisobutyrate using curving fitting. The effects of the reaction conditions on the conversion of reactants were investigated in detail. The results indicated that the conversion of reactants is highly dependent on the concentration of alkaline compound in the aqueous solution. An optimum value of alkaline concentration to produce a maximum conversion of reactant was obtained. Moreover, the conditions for reducing the hydrolysis of halo ester by adding sodium carbonate are recommended.

Carbon nanotubes with large cores produced by adding sodium carbonate to the catalyst

Carbon nanotubes with large cores produced by adding sodium carbonate to the catalyst

Separation and Enzymatic Saccharification of Cellulose from Wakame (Undaria pinnatifida)

Cellobiose and glucose were produced using an enzyme (cellulase from Trichoderma viride) reaction from the crude fiber unit (CFU) separated from Wakame seaweed (Undaria pinnatifida). The method for separation involved adding sodium carbonate (Na2CO3) to desalted stalks of wet Wakame. The wet CFU was pulverized using a centrifugal grinder after lyophilization. The enzyme reaction used the CFU powder as a substrate. The maximum concentration of cellobiose and glucose reached 56±2.0 and 130±0.2 mg/g, respectively. The total cellulose included in this CFU was determined to be about 70%. The sugar recovery from cellulose in the CFU was 20%. Although glucose was detected when micro-crystalline cellulose was used as a substrate, cellobiose and glucose were detected when CFU powder was used as a substrate.

L-649,923 — The selection of an appropriate salt form and preparation of a stable oral formulation

L-649,923 is an orally active leukotriene D 4 antagonist and the salt of a γ-hydroxy acid. It was formulated as a physically and chemically stable compressed tablet dosage form. Because the free acid was inherently unstable, the physical and chemical properties of the sodium, calcium, ethylenediamine and benzathine salts were evaluated and the calcium salt selected as the most pharmaceutically acceptable form of the drug for formulation development. The principal route of degradation was through an intramolecular esterification to yield the γ-lactone. Degradation could be monitored by following the appearance of the γ-lactone with an HPLC assay. A mechanism of degradation was proposed resembling acid-catalyzed solution esterificatiom occuring in the sorbed moisture. This postulate was used as a predictive model. Formation of γ-lactone was minimized in a direct compression tablet formulation by reducing the amount of free acid in the drug substance, avoiding an aqueous granulating process, using excipients with low water content and adding sodium carbonate as an alkalizing agent.

Cellulose dyeing parameters of 18 isomeric phenylazo‐H‐acid dyes containing two different reactive groups

Eighteen isomeric dyes, each based on phenylazo‐H‐acid and containing two reactive groups, namely a monochlorotriazine group and a sulphuric acid ester of ß‐hydroxyethylsulphone, were applied to cotton fabric by an exhaustion process at 60d̀C. The following properties were studied: spectra, uptake curves of the dyes before and after adding sodium carbonate, affinity, diffusion rate, and rates of hydrolysis and of reaction with cellulose, as evidenced by fixation and colour yield. Some significant correlations were found, but some missing or poor correlations indicated that there are further parameters or relationships between parameters that remain to be elucidated.

33-Day laceration stay

The rate of hydrolysis of the formyl moiety of cefamandole nafate was determined as a function of pH, temperature, and concentration of added sodium carbonate or tromethamine. The reaction rate was sensitive to hydroxide ion in the pH 5.5–8.0 range with half‐life values of hours to minutes. Hydrolysis was rapid upon the addition of sodium carbonate or tromethamine. Chirality in the 7‐D‐mandelamido side chain was unaffected by hydrolysis.

The corrosion of nuclear fuel (UO 2) in oxygenated solutions

The corrosion mechanism of UO 2 (nuclear fuel) has been studied in 0.1 mol l −1 sodium perchlorate (pH = 9.5), with and without added sodium carbonate. The corrosion potential was followed for various exposure times. Subsequently, the electrode was either subjected to a cathodic stripping scan from the corrosion potential to −2.0 V to determine the presence and measure the thickness of surface films formed; or removed and examined by X-ray photo-electron spectroscopy to determine the composition of the electrode surface. In both perchlorate and perchlorate plus carbonate solutions two films were formed on the UO 2 prior to the establishment of steady-state dissolution conditions. A layer of UO 2.33 was formed over the first 10 h of exposure. The outer layers of this film slowly converted to hydrated UO 3 (or uranyl carbonate) over the next ∼90 h. This conversion appeared to be concentrated at the grain boundaries. Corrosion rates were measured by extrapolating from the Tafel region for steady-state anodic dissolution to the corrosion potential. The corrosion process appears to be controlled by the kinetics of the anodic dissolution step.

Improved Media for Sporulation and Enterotoxin Production by Clostridium perfringens

Sporulation of 24 strains of Clostridium perfringens isolated from stools of food poisoning patients and normal controls was improved by adding sodium carbonate to Duncan-Strong (DS) sporulation medium and replacing starch with raffinose in Taniguti's AEA medium. Viable counts of heat-tolerant spores (75°C for 20 min) were 2 to 186 times greater in modified AEA medium and 2 to 169 times greater in modified DS than in DS medium. Reversed passive latex agglutination assays revealed a corresponding increase in enterotoxin titers in supernatant fluids of the 12 enterotoxigenic strains grown in modified AEA medium and in modified DS medium.

An investigation of the interactions between electrolytes and a zwitterionic surfactant using 23Na and 2H NMR measurements

NMR quadrupole splittings (Δ- 23Na) have been measured for sodium ions in the hexagonal phase formed by dodecyl/tetradecyl( 60 40 )dimethyl amine oxide (C 12–14AO) water( 2H 2O) mixtures, as a function of added sodium carbonate (“salting-out” electrolyte), sodium chloride (indifferent electrolyte), and sodium thiocyanate (“salting-in” electrolyte). Water quadrupole splittings (Δ- 2H) were also measured to give information on changes in the concentration and ordering of bound water. Further measurements were made on samples containing mixed electrolytes (NaCl/Na 2CO 3, NaSCN/NaCl, Na 2CO 3 NaSCN ). The salting-out electrolyte (Na 2CO 3) causes Δ- 23Na to become more negative, while the salting-in electrolyte (NaSCN) gives more positive Δ- 23Na values with NaCl giving intermediate results. The magnitude of Δ- 2H is increased with added sodium carbonate and decreased by addition of sodium thiocyanate, but higher electrolyte concentrations are required to cause alterations in Δ- 2H than are required to change Δ- 23Na. High levels of NaSCN causes both Δ- 2H and Δ- 23Na to change sign. At added electrolyte levels less than ca. 0.05 m values of Δ- 23Na and Δ- 2H are invariant. Increasing surfactant concentration (40–60%) generally gives larger Δ values. The NMR quadrupole splittings of both sodium and water are consistent with the idea that positive adsorption of anions at the micelle surface occurs when salting-in electrolytes are present, while negative adsorption of anions takes place with salting-out electrolytes.

Coal liquids distillation tower corrosion: correlation of on-stream monitoring with process variables at the Wilsonville, Alabama, SRC-1 pilot plant

Corrosion incidents in the fractionation area of direct coal liquefaction pilot plants have been severe. The Wilsonville, Alabama Solvent Refined Coal (SRC)-1 pilot plant operators quickly identified chloride, a minor component of the feed coal, as a contributing factor to this corrosion. They also learned that adding sodium carbonate to the coal feed was an effective way to provide a short-term measure to reduce corrosion; however, processing conditions would not permit the addition of alkali salts in a commercial plant. The extent of the corrosion at the atmospheric distillation tower of the Wilsonville plant has been continuously monitored for over a year. The results are reported here. The corrosion behavior is correlated with operational and feedstock parameters. The information reported here provides a basis for related investigations dealing with the analysis of process samples and laboratory corrosion experiments.

Stability of pectins during storage

SummaryLow methoxyl pectins (LMP) prepared by HCl, NaOH and NH3 deesterification procedures were stored with or without adding Na2CO3 as buffer at room temperature (25–30°C) or exposed to different relative humidities (r.h.) at 37°C. Losses of methoxyl, molecular weight and gelling power were observed in all the pectin samples. During storage, NaOH and NH3 deesterified LMP were more stable than HCl deesterified LMP with respect to gelling power. The monolayer values (Vm) of 0.5 to 0.7 g per 100 g of LMP showed that even when stored at 11% r.h., the moisture in LMP was present in the multilayer region which was conducive to methoxyl loss.NH3 deesterified LMP precipitated at pH 0.5 and 1.5 after saponification, formed good gels similar to the LMP precipitated at pH 0.5, dried and mixed with buffer. NH3 deesterified LMP precipitated at pH 3.0 and 4.5, on the contrary, formed only coagulated gels.The loss of gelling power of LMP during storage was due to depolymerization besides gradual transformation of increasing portions of pectinic acid molecules into pectic acid molecules. High methoxyl pectins with or without added sodium carbonate or citrate as buffer stored at 62 and 75% r.h. showed methoxyl loss. Between r.h. of < 0.1 and 49%, methoxyl loss was more in the buffered samples than in the control.