Addition Of Na2CO3 Research Articles

Extraction of lipase from Rhizopus microsporus fermentation culture by aqueous two-phase partitioning

The purification of a desired protein from the complex mixture of biomolecules in a fermentation broth is one of the main challenges in industrial-scale biotechnological processes. For partial purification of industrial enzymes, one possible approach is to use aqueous two-phase extraction (APTE) as a primary downstream processing step. In the present study, the feasibility of utilizing ATPE for the purification of lipase from Rhizopus microsporus fermentation culture was investigated. The effects of the phase composition and salt type, molecular weight of the polyethylene glycol (PEG), pH of the system, sample loading and addition of neutral salts on lipase partitioning were investigated at 24 °C. In most of the examined aqueous two-phase systems (ATPSs), lipase showed affinity to the top phase. Optimum conditions for lipase purification were obtained in 20% PEG 2000/12% (NH4)2SO4, with 5% Na2CO3 addition at pH = 8 for 30% crude load. For the optimized ATPS, the recovery yield and purification factor in the top phase were determined to be 92.3% and 19.8, respectively.

Lead extraction from cathode ray tube funnel glass melted under different oxidizing conditions

Lead was extracted into hydrochloric acid from cathode ray tube funnel glass melted under reducing atmosphere, oxidizing atmosphere, or a sequential combination of both to mechanistically investigate effects of the melting atmosphere on lead extraction. Melting funnel glass in a reductive atmosphere led to the generation of metallic lead particles that were readily soluble in the acid, increasing the quantity of lead extracted into the acid. Meanwhile, the glass product obtained after melting funnel glass in an oxidative atmosphere exhibited higher corrosion resistance in the acid, and the quantity of lead extracted from the treated glass decreased. However, Na2CO3 addition to the glass during melting hindered the enhancement of corrosion resistance and the immobilization of lead in the acid. X-ray photoelectron spectroscopic analysis of the treated glass samples showed that the positions of the peak or the profiles of the spectra attributed to Pb 4f, Si 2p, and O 1s signals were modified by oxidative melting, an indication that oxidative melting results in structural changes in the SiO2 framework of the glass.

A comparative study of inorganic alkaline/polymer flooding and organic alkaline/polymer flooding for enhanced heavy oil recovery

In this paper, interfacial tension measurements, emulsification tests, viscosity measurements, sandpack flooding tests and micromodel flooding tests were conducted for the comparative study of inorganic alkaline/polymer flooding and organic alkaline/polymer flooding for enhanced heavy oil recovery. The IFT measurement results show that NaOH, ethylenediamine and Na2CO3 all can reduce oil–water IFT to lower than 10−1 mN/m. The addition of 0.1 wt% HPAM exerts favorable effect on the reduction of IFT between oil and alkaline solutions. Emulsification tests show that when alkaline concentration is 1.0 wt%, ethylenediamine can emulsify the heavy oil into stable O/W emulsion while 1.0 wt% NaOH emulsify the heavy oil into W/O emulsion (with a formation water containing 0.5 wt% NaCl). Viscosity measurements show that the addition of ethylenediamine can slightly increase the viscosity of polymer while the addition of NaOH and Na2CO3 can significantly reduce the viscosity of the polymer. Sandpack flooding tests show that the incremental oil recovery by ethylenediamine–HPAM flooding is higher than those by NaOH–HPAM flooding and Na2CO3–HPAM flooding. Accordingly, ethylenediamine–HPAM flooding has some advantages over inorganic alkaline/polymer flooding for enhanced heavy oil recovery.

Recovery of metallic iron from high phosphorus oolitic hematite by carbothermic reduction and magnetic separation

This study aims to provide theoretical and technical basis for economical and rational use of high phosphorus oolitic hematite. Following physical, chemical and microscopic characterisation of high phosphorus oolitic hematite ore the feasibility of separation of phosphorus and metallic iron by reduction roasting and magnetic separation process were investigated. The results indicate that such a process is a feasible and efficient method for iron and phosphorus separation of high phosphorus oolitic hematite. The recovery of metallic iron and dephosphorisation rate is relatively low without additives but is significantly improved by appropriate CaO and Na2CO3 addition. With 8%CaO and 3%Na2CO3 the recovery of metallic iron and dephosphorisation rate reach 95.1 and 94.0% respectively.

Effect of sodium compounds on the sintering propensity of coal-associated minerals

This study focused on the chemistry involved in sintering of coal-associated minerals during combustion and inert conditions. Changes in mechanical strength were recorded with compressive strength measurements. This method was used to investigate the influence of sodium addition (as NaCl and Na2CO3) on the sintering strength of a prepared mineral mixture at temperatures ranging from 500°C to 1000°C. Supporting data were collected with thermogravimetry (TG), differential thermal analysis (DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the addition of both NaCl and Na2CO3 increased the sintering of the mixture by between 20% and 80% at temperatures ranging from 500°C to 800°C in air. The increase in sintering was most likely due to the enhanced sulphation of limestone to anhydrite, resulting in a more extensive sintered network. Anhydrite decomposes at temperatures higher than 900°C. At 900°C and 1000°C the sintering observed for the mixture with additives was comparable to the sintering observed for the baseline mixture. The decomposition of anhydrite therefore weakened the sintered network to the same level as the baseline mixture. In an inert atmosphere (N2) the same strength development as in the mixture heat-treated in air was not observed in mixtures with sodium additives. Anhydrite was not formed in N2 due to the lack of O2 and SOx. A decrease in the sintering propensity upon heat-treating the samples from 700°C to 1000°C in N2 for the experiments containing NaCl as additive was noted. This was most likely due to the volatilization of NaCl that weakened the structure. The addition of Na2CO3 increased the sintering propensity of the mixture heat-treated in N2 from 500°C to 800°C. The mechanism for this increase is currently unknown and should be further investigated.

Development of the Al2O3-supported NaNO3-Na2Mg(CO3)2 sorbent for CO2 capture with facilitated sorption kinetics at intermediate temperatures

For the development of a dry solid sorbent having quite fast CO2 sorption kinetics in an intermediate temperature range of 245–300 °C to be applicable to a riser-type fluidized bed carbonator, samples of Al2O3-supported MgCO3 (1.2 mmol/g) promoted with different molar amounts of Na2CO3 (1.2, 1.8 mmol/g) and/or NaNO3 (0.6 mmol/g) were prepared by incipient wetness pore volume impregnation. For a reference, an unsupported bulk phase sorbent of NaNO3-Na2Mg(CO3)2 was also prepared. From the sorption reaction using a gas mixture containing CO2 by 2.5–10% at 1 bar for the sorbents after their activation to MgO, Al2O3-supported sorbents were featured by their rapid carbonation kinetics in contrast to the unsupported sorbent showing a quite slow carbonation behavior. The addition of Na2CO3 to the MgCO3/Al2O3 sorbent made MgO species more reactive for the carbonation, bringing about a markedly enhanced kinetic rate and conversion, as compared with the unpromoted MgCO3/Al2O3 sorbent having a small negligible reactivity. The addition of NaNO3 to MgCO3/Al2O3 or to Na2CO3-MgCO3/Al2O3 induced the same promotional effects, but to a lesser magnitude, as observed for the Na2CO3 addition. It was also characteristic for all these MgCO3-based sorbents that initial carbonation conversions with time appeared as sigmoid curves. For the Al2O3-supported sorbent comprised of NaNO3, Na2CO3, and MgCO3 by 0.6, 1.8, and 1.2 mmols, respectively, per gram sorbent, showing the best kinetic performance, a kinetic equation capable of reflecting such sigmoid conversion behavior was established, and its applicability to a riser carbonator was examined throughout a simple model calculation based on the kinetics obtained.

Effect of Na2CO3 additive on the activation of coal gangue for alumina extraction

The effect of Na2CO3 additive on the activation of coal gangue for alumina extraction was investigated. The discussion on the action mechanisms was performed by the means of TG-DSC, XRD and XRF. The results showed that the calcined coal gangue with the addition of Na2CO3 improved the alumina extraction significantly. At the calcination temperatures of 800–900°C with Na2CO3 to coal gangue weight ratios of 0.8–1, the alumina extractions of >90% were obtained. There were reactions between Na2CO3 and coal gangue during the calcination to form nepheline, which improved the dissolution of Al2O3 in acid and enriched SiO2 concentration in the residue during the acid leaching process. Na2CO3 could attack AlO6 and SiO4 network in coal gangue owing to the compensation charge effect, and therefore facilitate the decomposition of coal gangue.

The effect of additives on the properties of lightweight aggregates produced from clay

In an attempt to improve the properties, lightweight aggregates were produced from clay with the addition of Na2CO3, SiO2, Fe2O3, and Fe in quantities between 2 and 10 wt% and examined with respect to strength, density and expansion behavior. The additives were mixed into dry clay powder, water was added and pellets were formed by hand and fired at 1120°C in a chamber furnace. Particle densities of the products ranged from 0.31 to 0.57g/cm3, porosities from 78% to 89% and the solid strength from 0.54 to 1.58MPa. The addition of Na2CO3 proved to decrease the viscosity of the glass phase at the surface of the pellets but resulted in a reduced expansion, irregular shape and pellets sticking together. SiO2 addition did not give any major change in properties. The addition of Fe2O3 increased the pore size in the center of the pellets, however with insignificant change in strength and density. Adding 5 wt% metallic iron powder led to LWA pellets with increased porosity, reduced density, larger pores and low mechanical strength and could be a useful additive in applications where low density is more important than strength.

Experimental and Modeling Study on de-NOx Characteristics of Selective Non-catalytic Reduction in O2/CO2 Atmosphere

An experimental study of thermal de-NOx using NH3 as reductant in O2/CO2 atmosphere with the effect of SO2 and different additives was performed in a drop tube furnace. Results show that the optimum temperature window is 841–1184°C, and the optimum reaction temperature is about 900°C with a de-NOx efficiency of 95.4%. A certain amount of SO2 has an inhibiting effect on NO reduction. The effect of additives, including Na2CO3, C2H5OH and FeCl3, on NO reduction by NH3 is also explored. The addition of Na2CO3 and FeCl3 is useful to widen the temperature window and shift the reaction to lower temperature for the efficiency is increased from 30.5% to 74.0% and 67.4% respectively at 800°C. Qualitatively, the modeling results using a detailed kinetic modeling mechanism represent well most of the process features. The effect of Na2CO3, C2H5OH and FeCl3 addition can be reproduced well by the Na2CO3, C2H5OH and Fe(CO)5 sub-mechanism respectively. The reaction mechanism analysis shows that the effects of these additives on NO reduction are achieved mainly by promoting the production of OH radicals at lower temperature.

Efficient mobilization and fractionation of rare-earth elements by aqueous fluids upon slab dehydration

The characteristic REE fractionation pattern in arc magmas compared to MOR-basalts results from the selective mobilization of light rare-earth elements (LREE) by slab-derived mobile components. However, the nature and composition of the slab flux, and the actual mechanisms responsible for the transfer of rare-earth elements (REE) from the slab to the mantle wedge remain unclear. We present experimental data on the solubility of selected REE in ligand-bearing aqueous fluids and a hydrous haplogranitic melt at 2.6 GPa and 600–800 °C, spanning the conditions relevant to slab dehydration and melting. The solubilities of REE in aqueous fluids increase more than an order of magnitude with temperature increasing from 600 to 800 °C. Addition of ligands such as Cl−, F−, CO32−, SO42− in relatively small concentrations (0.3–1.5 m [mol/kg H2O]) has a pronounced effect further enhancing REE solubilities. Each ligand yields a characteristic REE pattern by preferential dissolution of either the light or the heavy REE. For example, the addition of NaCl to the aqueous fluids yields highly elevated LREE/HREE ratios (La/Yb=17.4±4.3), whereas the addition of fluoride and sulfate ligands significantly increases the solubility of all REE with moderate LREE/HREE fractionation (La/Yb∼4). The addition of Na2CO3 results in preferential increase of HREE solubilities, and yields La/Yb ratio of 1.6±0.5 by flattening the moderately fractionated REE pattern seen in pure aqueous fluids. The solubilities in hydrous haplogranite melt are moderate in comparison to those observed in aqueous fluids and do not lead to pronounced REE fractionation. Therefore, REE can be effectively mobilized and fractionated by aqueous fluids, compared to felsic hydrous melts. Furthermore, the aqueous fluid chemistry has a major role in determining REE mobilities and fractionation upon slab dehydration in addition to the significant control exerted by temperature. Our results show that chloride-bearing slab-derived aqueous fluids have a significant contribution to the formation of REE-signatures in arc-magmas, especially at lower slab surface temperatures.

A facile fabrication of NiO nanoparticles from spent Ni–Cd batteries

In line with recycling and valuating the spend materials, we developed,in this work, a facile and innovative synthetic route to prepare NiO nanoparticles from spent Ni–Cd batteries, the nickel of which was obtained by H2SO4 leaching. Then, using Na2CO3 addition into the purified Ni-aqueous solution, the NiO nano-particles׳ precursor was obtained. Eventually, the NiO nanoparticles were synthesized by thermal decomposition of the precursor at 450°C. In turn, the synthesized materials were characterized by means of XRD, TEM, thermogravimetric analysis–differential scanning calorimeter (TGA–DSC) and infrared spectrum (IR) techniques.

Carbonation of municipal solid waste incineration electrostatic precipitator fly ashes in solution

Carbonation was applied to a Pb- and Zn-contaminated fraction of municipal solid waste incineration electrofilter fly ashes in order to reduce heavy metal leaching. Carbonation tests were performed in solution, by Na2CO3 addition or CO2 bubbling, and were compared with washing (with water only). The injection of CO2 during the washing did not modify the mineralogy, but the addition of Na2CO3 induced the reaction with anhydrite, forming calcite. Microprobe analyses showed that Pb and Zn contamination was rather diffuse and that the various treatments had no effect on Pb and Zn speciation in the residues. The leaching tests indicated that carbonation using Na2CO3 was successful because it gave a residue that could be considered as non-hazardous material. With CO2 bubbling, Pb and Zn leaching was strongly decreased compared with material washed with water alone, but the amount of chromium extracted became higher than the non-hazardous waste limits for landfilling.

Management of thiosalts in mill effluents by chemical oxidation or buffering in the lime neutralization process

Laboratory studies were conducted to investigate the removal or management of thiosalts within the lime-neutralization process, to prevent or minimize the adverse effects of thiosalts that cause delayed acidity to downstream environment. The oxidizing reagent hydrogen peroxide (H2O2) and the pH stabilizing (buffering) reagents carbon dioxide (CO2), sodium bicarbonate (NaHCO3) and sodium carbonate (Na2CO3) were examined for removal and management of thiosalts, respectively. Chemical oxygen demand (COD) was determined to be a proxy for thiosalts and was employed for their rapid assessment. The Target Level of thiosalts harmless to aquatic life was found to be 30mg/L or less. The optimized lime-neutralization process required a pH level of 9.5–10 and aeration. Over-liming to pH levels >11 did not provide excess alkalinity, hardness, or a decrease in thiosalt levels.Addition of H2O2 to either the acid or lime-neutralized water at a molar H2O2:S2O3 ratio of 1–1.5 removed thiosalts to safe levels. About 10–15min. at room temperature was ample time low temperatures slowed down the process but the dosages were not affected. Removal of thiosalts from 170 to 30mg/L caused a decrease in pH from 9.6 to 6.5. Among the buffering reagents studied, both NaHCO3 and Na2CO3 provided adequate buffering and a stable pH of 7 to the lime-neutralized water; whereas CO2 resulted in poor buffering and an unstable pH that remained below 6. In cold temperatures, NaHCO3 and Na2CO3 also outperformed CO2 with higher alkalinity and hardness. Na2CO3 addition to lime neutralized water at pH 9.5 was found to be the most cost-effective option. Other methods could have niche applications, depending on seasonal variations and temperature.

Novel Process for Alumina Extraction via the Coupling Treatment of Coal Gangue and Bauxite Red Mud

A novel process for the coupling treatment of coal gangue and red mud is reported. Red mud containing 23.4% Al2O3, 19.1% SiO2, and 9.4% Na2O by weight was used as the blended ingredients of coal gangue for alumina extraction. Calcination of coal gangue with the addition of Na2CO3 at 850 °C could obtain more than 90% of Al2O3 extraction. Nevertheless, the high consumption of Na2CO3 is equivalent to the same weight amount of coal gangue. Both nepheline and sodium aluminum silicate formed during the process have the molecular structure of NaAlSiO4. The 1:1:1 of the theory molar ratio of Na, Al, and Si suggested that the minimum consumption of Na2CO3 might be obtained at the optimal Al/Si molar ratio of 1:1. Red mud with an Al/Si molar ratio of 1.44 mixed with coal gangue with a ratio of 0.64 was used to extract alumina. The results showed that red mud could adjust the Al/Si molar ratio of coal gangue to an appropriate value and Na2O in red mud was also used to partly substitute for Na2CO3 required for coal gangue activation, which consequently decreased the consumption of Na2CO3 from 100% to 12.1–20.5%.

Thermodynamic performance assessment and comparison of IGCC with solid cycling process for CO2 capture at high and medium temperatures

Solid sorbents can be used to capture CO2 from pre-combustion sources at various temperatures. MgO and CaO are typical medium- and high-temperature CO2 sorbents. However, pure MgO is not active toward CO2. The addition of Na2CO3 increases the operating temperature and significantly increases the reactivity of sorbents to capture CO2. Na2CO3-promoted MgO is a promising medium-temperature CO2 sorbent. In this study, the thermodynamic performance of integrated gasification combined cycle (IGCC) systems with Na2CO3–MgO-based warm gas decarbonation (WGDC) and CaO-based hot gas decarbonation (HGDC) is evaluated and compared with that of an IGCC system with methyldiethanolamine (MDEA)-based cold gas decarbonation (CGDC). Assuming that the average CO2 capture capacities of solid sorbents are one-third of their theoretical maxima, we reveal that the IGCC system undergoes approximately 2.8% and 3.6% improvement on net efficiency when switching from CGDC to WGDC and to HGDC, respectively. The net efficiency of the system is increased by improving the CO2 capture capacity of the sorbent. The IGCC with Na2CO3–MgO experiences more significant increase in efficiency than that with CaO along with the improvement of sorbent average CO2 capture capacity. The efficiency of the IGCC systems reaches the same value when the average CO2 capture capacities of both sorbents are 53% of their theoretical levels. The effects of gas turbine combustor fuel gas inlet temperature on IGCC system performance are analyzed. Results show that the efficiency of the IGCC systems with HGDC and WGDC increases by 0.74% and 0.53% respectively as the fuel gas inlet temperature increases from 250 °C to 650 °C.

The Crystal Structure, Conductivity Character and Ionic Migration of Samarium Doped-Ceria (SDC) and its Composite with Sodium Carbonate

This paper discusses the crystal structure, the conductivity character and ionic migration inside Sm0.2Ce0.8O1.9 (SDC) crystal and it’s composite with sodium carbonate salt, Na2CO3 (NSDC). XRD measurement equipped with Le Bail refinement shows that SDC crystallized in single phase of cubic with space group of Fm3m. The addition of Na2CO3 does not change the crystal structure of SDC however it increases the cell parameters. NSDC has a lower ionic conductivity than the SDC at the same temperature. However at 600 °C, SDC provides electronic conductivity which indicates the diffusion of electrons between the electrolyte and electrode caused by the reduction of Ce(IV) to Ce(III). It may cause a short circuit and the fuel cell performance if it is used as electrolyte. Meanwhile, NSDC still produces pure ionic conductivity at 600 °C which indicates a better chemical stability. Based on its capacitance values, it is known that the ionic conductivity of SDC is generated by migration of ions inside grain, while the conductivity of NSDC is generated by the migration of ions between grains or it is named as grain boundaries conductivity.

Preparation and characterization of novel hydroxyapatite/copper assemblies with well-defined morphologies

Micrometer-sized powders with small crystallite sizes, high dispersion, and high copper contents, like Cu and/or Cu2O assembled on core particles would find potential applications in fields of catalysts, transparent conducting films and plasmonic-based technologies. Novel hydroxyapatite (HA)/copper assemblies were synthesized via a facile glucose reduction route. During hydrothermal treatment, copper ions were firstly released after dissolution of copper-modified HA, then reduced by glucose and finally assembled as shell on HA aggregates. After 12 h, cuprous oxide grew with truncated-octahedron morphology. When the reduction time was prolonged to 24 and 36 h, Cu phase was formed in situ via glucose reduction of Cu2O. Interestingly, HA/copper assemblies with well-defined morphologies were prepared under different reaction conditions. With presence of more Na2CO3, the reduction of copper ion occurred at a fast rate, which resulted in formation of spherical assemblies. Contrastingly, reduction reaction hardly occurred without Na2CO3 addition and assemblies with irregular morphology were prepared. Additionally, copper fibers with length of millimeters were prepared without Na3Cit addition. The UV–Vis absorbance peak of assemblies showed a blue or red shift due to the effect of crystalline size and/or hollowing process.

Desulphurisation mechanism of direct reduction and melting in carbon bearing pellets

The iron nugget process which utilises carbon bearing pellets is a flexible, economical and environmentally friendly iron making process. Iron nuggets which have physicochemical properties similar to those of pig iron can be obtained in a short time through high temperature smelting reduction. Sulphur content has an important influence on the quality of the iron nuggets produced. The behaviour of sulphur in the carbon bearing pellets was studied during heating at 1450°C using chemicals of analytical reagent grade as raw materials. The effect of reduction conditions, such as reduction temperature, C/O mole ratio, reducing agent species, basicity and additive agent, on the sulphur content in iron nuggets and slag after separation was investigated. Sulphur disperses in pellets in the initial stage of reduction as a result of reagent mixing. As reduction and melting proceed, sulphur is accumulated at several points in iron and slag. Slag demonstrates a strong desulphurisation ability. Very high temperatures are not conducive for reducing the sulphur content in iron nuggets. Sulphur content in iron nuggets decreases with increasing C/O ratio, basicity and the addition of Na2CO3 as a desulphurisation agent. Iron and slag can be well separated to yield high quality iron nuggets by controlling the process parameters.

High-throughput nitritation of reject water with a novel ammonium control loop: Stable effluent generation for anammox or heterotrophic denitritation

This work presents a new control system for the nitritation of high-strength ammonium wastewater as reject water from sludge dewatering. It is based on three independent feedback control loops: (i) DO control by manipulating the aeration flow-rate, (ii) pH control with the addition of solid Na2CO3 and (iii) control of NH4+–N concentration in the reactor using the influent flow-rate as the manipulated variable. Its application in an activated sludge configuration with one reactor and a settler, demonstrated: (i) capability to achieve stable effluent composition with proper NO2-–N/NH4+–N ratio for anammox treatment and ii) possibility to obtain an effluent with full nitritation suitable for heterotrophic denitrification only modifying the ammonium setpoint. A nitrogen loading rate (NLR) up to 5.0±1.0gNL−1d−1 was stably treated using real reject water (T=30°C, pH=7.5) with a NO2-–N/(NO2-–N+NO3-–N) ratio of 99%. NLR reached up to 9.3±0.5gNL−1d−1 with synthetic wastewater.

A facile method to synthesis of CdO nanoparticles from spent Ni–Cd batteries

As an innovative route, in this research, to synthesize CdO nanoparticles, firstly the anode materials of the spent Ni–Cd batteries was leached by H2SO4, secondly the CdO nano-particles’ precursor (Otavite (CdCO3) powder) obtained from the leaching solution by Na2CO3 addition, and finally the CdO nanoparticles synthesized by thermal decomposition of the precursor at 500°C. To characterize the synthesized materials, XRD, SEM, thermogravimetric analysis-differential scanning calorimeter (TGA–DSC) and infrared spectrum (IR) techniques were used. According to the results, spherical, pure CdO nanoparticles (about 40nm in size) were successfully prepared without using organic solvent, expensive raw materials, and complicated equipment.