Addition Of MgCO3 Research Articles

Hexanoic acid production and microbial community in anaerobic fermentation: Effects of inorganic carbon addition

Carbon dioxide (CO2) plays a crucial role in carbon chain elongation with ethanol serving as an electron donor. In this study, the impacts of various carbonates on CO2 concentration, hexanoic acid production, and microbial communities during ethanol-butyric acid fermentation were explored. The results showed that the addition of MgCO3 provided sustained inorganic carbon and facilitated interspecific electron transfer, thereby increasing hexanoic acid yield by 58%. MgCO3 and NH4HCO3 inhibited the excessive ethanol oxidation and decreased the yield of acetic acid by 51% and 42%, respectively. The yields of hexanoic acid and acetic acid in the CaCO3 group increased by 19% and 15%, respectively. The NaHCO3 group exhibited high headspace CO2 concentration, promoting acetogenic bacteria enrichment while reducing the abundance of Clostridium_sensu_stricto_12. The batch addition of NaHCO3 accelerated the synthesis of hexanoic acid and increased its production by 26%. The relative abundance of Clostridium_sensus_stricto_12 was positively correlated with hexanoic acid production.

Enhancing the mechanical properties of Mg-Zn-Al-Cu-Mn alloy via MgCO3 inoculation treatment: Experimental studies and first-principles calculations

In this work, the low-cost Mg-10Zn-1Al-0.5Cu-0.3Mn without or with the addition of MgCO3 (labeled as S1 and S2 alloys) was successfully fabricated by a rapid-setting water-cooling method. The average grain size of the as-cast alloy decreased from 38.5 to 22.5 µm with the addition of MgCO3. S2 alloy possessed excellent ultimate tensile strength and elongation of 275.6 MPa and 17.5 % in the solid solution state, which were approximately 21.6 and 82.3 % higher than those of the S1 alloy. The transmission electron microscopy results showed that the MnAl2O4 phase with a high melting point was formed in the melt of S1 alloy by adding 1 wt% MgCO3, which had a phase relationship of (101)Mg||(311)MnAl2O4. Additionally, the results of edge-to-edge matching model showed that the MnAl2O4 phase tended to grow on the Mg matrix phase. The results of the first-principles calculations exhibited that the (101)Mg||(311)MnAl2O4 interface with MnO terminations was a strong interface. The MnAl2O4 phase could be regarded as heterogeneous nucleation points to improve the nucleation rate and thus to refine the grain and enhance the strength. This study can vigorously provide a certain guide for the grain refinement of Mg-Zn based alloys containing Mn.

Analysis of corrosion of corundum refractory castables in relation to increased MgO content in dendromass ashes

Biomass ash has a significantly lower proportion of Al2O3 and higher proportions of K2O, CaO and SiO2 than coal ash. Biomass combustion in power plants increases demands on refractory linings and metal fittings in boilers. Grates and linings of combustion chambers in furnaces and boilers are more susceptible to clogging and are degraded by bio-ash slag. The results of this study suggest that the addition of approximately 2% of powder magnesite waste to the wood-chip fuel can significantly mitigate ash slagging and also corrosion of the corundum refractory material. With regard to the resulting increased MgO content in the dendromass ash, the corrosion of corundum refractory material was studied. The MgO content in the ash was increased by adding powder magnesite waste to ash samples. The results of corrosion tests (1450 °C/7 h) showed that ash slag with MgCO3 addition corroded the corundum material less. Analyses of the post-mortem slag and corrosion interface confirmed: (i) higher K2O concentration in the ash caused increased corundum material corrosion by both vapours (g-s) and melt (l-s); (ii) K2O reacted with Al2O3 at the corrosion interface and also penetrated intensively into the fine-grain matrix by surface diffusion; (iii) MgO remained in the slag; (iv) increased Al2O3 content in the molten slag initiated a liquation of MA-spinel. These results (especially MA spinel liquation from the slag and K2O diffusion through the matrix followed by micro-grain dissolution) indicate that replacing the mullite binder phase in the matrix with MgO and/or spinel could lead to improved resistance of the refractory material to biomass ash slag.

Removal of Arsenate from Contaminated Water via Combined Addition of Magnesium-Based and Calcium-Based Adsorbents

The effects of the combined addition of Mg- and Ca-based adsorbents (MgO, Mg(OH)2, MgCO3, CaO, Ca(OH)2, and CaCO3) were systematically tested for improving arsenic-removal performance and inhibiting the leaching of base material components from the adsorbent. Arsenic-removal tests were conducted with each single type or combination of two types of adsorbents. Results obtained after the combined-addition tests were compared with those obtained from the single-addition test with each adsorbent. The arsenic-removal performance improved in most combined additions but decreased in certain combined additions of MgO or Mg(OH)2 with Ca-based adsorbents. The arsenic-removal performance of the combined addition of MgCO3 and Ca(OH)2 was the highest. The combination of Mg-based adsorbents with CaO or Ca(OH)2 inhibited Mg-leaching, whereas that of CaO or Ca(OH)2 with MgCO3 inhibited Ca-leaching. Improvement in arsenic-removal performance for the combination of MgCO3 with CaO or Ca(OH)2 was caused by the incorporation and co-precipitation with arsenic when Mg(OH)2 and CaCO3 were produced. MgCO3-Ca(OH)2 and MgCO3-CaO are recommended for both arsenic removal and environmental adsorbent stability that can be effectively applied over a wide range of arsenic concentrations.

Well Knowledge of the Physiology of Actinobacillus succinogenes to Improve Succinic Acid Production

The anaerobic fermentation of glucose and fructose was performed by Actinobacillus succinogenes 130Z in batch mode using three different volume of bioreactors (0.25, 1 and 3 L). The strategy used was the addition of MgCO3 and fumaric acid (FA) as mineral carbon and the precursor of succinic acid, respectively, in the culture media. Kinetics and yields of succinic acid (SA) production in the presence of sugars in a relevant synthetic medium were investigated. Work on the bench scale (3 L) showed the best results when compared to the small anaerobic reactor’s succinic acid yield and productivity after 96 h of fermentation. For an equal mixture of glucose and fructose used as substrate at 0.4 mol L−1 with the addition of FA as enhancer and under proven optimal conditions (pH 6.8, T = 37 °C, anaerobic condition and 1% v/v of biomass), about 0.5 mol L−1 of SA was obtained, while the theoretical production of succinic acid was 0.74 mol L−1. This concentration corresponded to an experimental yield of 0.88 (mol-C SA/mol-C sugars consumed anaerobically) and a volumetric productivity of 0.48 g-SA L−1 h−1. The succinic acid yield and concentration obtained were significant and in the order of those reported in the literature.

In situ construction of fiber‐supported micro‐porous char structure to enhance anti‐ablative performance of silicone rubber composites

AbstractAblation‐resistant polymeric composites play a crucial role in the thermal protection system for the entire aerospace industry. Constructing a stable char layer especially with low thermal conductivity is essential to enhance the ablation resistant properties of polymer‐based ablatives. In this article, basic magnesium carbonate (MgCO3) and carbon fibers (CFs) were introduced to silicone rubber with an aim of building fiber‐supported micro‐porous char structure in situ, thereby improving ablation resistance properties. Thermogravimetric analyses revealed that the addition of MgCO3significantly increased the char residue of the composites. Oxyacetylene torch tests indicated that the addition of MgCO3/CFs greatly improved the thermal insulation of the composites, and the linear ablation rates of the composites were reduced by 30.76% compared to the virgin silicone rubber. Shore A hardness and thermal conductivity tests revealed that composites with 10 phr MgCO3exhibited a char structure with proper strength and low thermal conductivity. SiC, Mg2SiO4, and MgSiO3were produced in the MgCO3/CFs‐modified composites, as characterized by X‐ray diffraction. Combined with macro lens and scanning electron misroscopy, it was proven that a fiber‐supported micro‐porous and thermally insulated char structure was conducive to the improvement of the ablation properties, which can be applied to aerospace systems for thermal shielding applications.

Effects of CaO-MgCO3 on the combustion behavior and emission properties of SO2 and NOx during semi-coke combustion

The effect of CaO-MgCO3 additives on the combustion property of semi-coke (SC) was investigated using thermogravimetric analysis. Based on the experimental results, the addition of CaO (Ca/S = 2) on SC could reduce the ignition temperature (about 1.3 °C) and burnout temperature (about 0.99 °C). Besides, the additive of CaO on SC had significantly decreased the emissions of SO2 and NOx. However, the addition of 1 wt% MgCO3 on SC-CaO could promote the burning process and remarkably reduce the ignition temperature (about 10 °C) and burnout temperature (about 8.64 °C). Moreover, the smallest activation energy was available for the combustion of SC-CaO-1 wt% MgCO3. On the other hand, the addition of MgCO3 with different content (0.5 wt%, 1 wt%, 2 wt%, 4 wt%) on SC-CaO could enhance the pore size of CaO, promote the sulfur fixation performance. Comparing with other SC-CaO-MgCO3 samples, the addition of appropriate amount of MgCO3 (1 wt%) could effectively promote the catalytic desulfuration and denitrification of CaO. Therefore, CaO-1 wt% MgCO3 could effectively inhibit SO2 and NOx emission, which had great potential to be an efficient and clean method for the large-scale utilization of semi-coke.

Effects of amendments on the alleviation of aluminum toxicity and cadmium and zinc uptake by Sedum plumbizincicola in acid soils

To explore the effects of some chemical amendments on the plant growth and phytoextraction efficiencies of cadmium (Cd)/zinc (Zn) hyper accumulator Sedum plumbizincicola in acid soils with high aluminum (Al) toxicity, a greenhouse pot experiment was conducted. Different kinds and dosages of amendments including calciummagnesium-phosphorus fertilizer (CMP), magnesium carbonate (MgCO₃), potassium dihydrogen phosphate (KH₂POPO₄ ) were added. The results showed that CMP and MgCO₃ increased soil pH and decreased soil exchangeable Al concentration to some extent, while KH₂PO₄ reduced soil exchangeable Al concentration but had little effect on increasing soil pH. Proper application (9.39 mg/kg) of CMP could improve the biomass and Cd and Zn phytoextraction efficiencies by S. plumbizincicola but it would inhibit plant growth and phytoextraction performance when exceeding 9.39 mg/kg. MgCO₃ addition enhanced plant metal uptake while KH₂PO₄ presented an opposite effect. It suggests that using CMP and MgCO₃ could alleviate Al toxicity to S. plumbizincicola in acid soils and maintain relatively high metal extraction efficiency.

Difference in pore evolution of calcium aluminate cement-bonded alumina bubble-based castables with micro-sized MgCO3 and Al(OH)3

Micro-sized MgCO3 and Al(OH)3 were used as inorganic porogenic agents for increasing porosity in alumina bubble lightweight castables. The influence of 0–4 wt% micro-sized MgCO3 and 0–8 wt% micro-sized Al(OH)3 additions on the porosity, thermal conductivity and strength of castables after firing was investigated. The results indicate that porosities in castables containing micro-sized Al(OH)3 or MgCO3 after heat-treatment were raised by augmenting micro-sized Al(OH)3 or MgCO3 contents. It is found that MgCO3 favors the porosity formation more than Al(OH)3 in castables because of the different formation behavior of calcium aluminates and MgAl2O4 spinel. The dependence of properties of castables on the micro-sized Al(OH) or MgCO3 addition was discussed with respect to the pore evolution.

Effect of micro-sized MgCO3 addition on properties of MgAl2O4 spinel containing castables

Abstract Micro-sized MgCO 3 was used in castables as the MgO-precursor for generating sub-micro sized MgO and for producing subsequent in-situ magnesium aluminate (MgAl 2 O 4 , MA) spinel. The influence of 0–2.0 wt% micro-sized MgCO 3 addition on the volumetric stability and thermo-mechanical properties of castables after firing at 1000 °C and 1550 °C was investigated. The in-situ spinel formation and its influence on the microstructure evolution in castable matrices with different micro-sized MgCO 3 contents after heat-treatment were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The dependence of the volume stability and thermo-mechanical properties of castables on the micro-sized MgCO 3 addition was discussed with respect to the in-situ spinel formation.

Fixings Agent Effect to β-carotene Stabilityof Crude Extract from Dunaliella salina Microalga at Different Temperature Condition

Abstract<br />Dunaliella salina is a microalga rich pigment carotenoids that can be used asnatural dyes. The problem<br />faced for temporative β-carotene stability which is unstable and easily degraded is unstable and easily<br />degraded. The purpose ofthis researchwas to determine content and stability of β-carotene pigment in<br />D.salina with fixings addition of MgCO3 and NaHCO3 with temperature treatment as factor that influence<br />β-carotene pigment degradation during storage condition. The research method used β-carotene pigment<br />which was obtainedbymaceration and adding fixing agent (NaHCO3 0,5% and without fixings addition),<br />and was heated at temperature of (50°, 70° and 90°C), be measured the content of β-carotene pigment<br />during storage (observation hour 0, 24, 48, 72, 96, 120 and 144). Data analyzed by ANOVA and Honestly<br />Significant Different (HSD). The result showed that content of β-carotene pigment at 50°C temperature<br />showed that stability and pH value performed slowest degradation after144 hours. While stability and pH<br />value at 90°C temperature performed fastest degradation after 96 hours. Based on this study the addition of<br />NaHCO3 gave more effective in retaining β-carotene degradation compared to that of MgCO3 which showed<br />by high stability in sample NaHCO3 0,5%, temperature 50°C in 144 hours storage length.<br /><br />

Fixings Agent Effect to β-caroteneStabilityof Crude Extract from Dunaliella salinaMicroalgaat Different Temperature Condition

faced for temporative β-carotene stability which is unstable and easily degraded is unstable and easily<br />degraded. The purpose ofthis researchwas to determine content and stability of β-carotene pigment in<br />D.salina with fixings addition of MgCO3 and NaHCO3 with temperature treatment as factor that influence<br />β-carotene pigment degradation during storage condition. The research method used β-carotene pigment<br />which was obtainedbymaceration and adding fixing agent (NaHCO3 0,5% and without fixings addition),<br />and was heated at temperature of (50°, 70° and 90°C), be measured the content of β-carotene pigment<br />during storage (observation hour 0, 24, 48, 72, 96, 120 and 144). Data were analyzed by analysis of variance<br />(ANOVA) and Honestly Significant Different (HSD). The result showed that content of β-carotene pigment<br />at 50°C temperature showed that stability and pH value performed slowest degradation after144 hours.<br />While stability and pH value at 90°C temperature performed fastest degradation after 96 hours. Based on<br />this study the addition of NaHCO3 gave more effective in retaining β-carotene degradation compared to that<br />of MgCO3 which showed by high stability in sample NaHCO3 0,5%, temperature 50°C in 144 hours storage<br />length.<br /><br />

Design of Controlled Release PLGA Microspheres for Hydrophobic Fenretinide.

Fenretinide, a chemotherapeutic agent for cancer, is water-insoluble and has a very low oral bioavailability. Hence, the objective was to deliver it as an injectable depot and improve the drug solubility and release behavior from poly(lactide-co-glycolide) (PLGA) microspheres by incorporating nonionic surfactants with fenretinide. Enhancement of drug solubilization was observed with Brij 35 or 98, Tween 20, and Pluronic F127, but not Pluronic F68. Co-incorporation of Brij 98 with fenretinide significantly changed the microsphere morphology and improved the fenretinide release profile. The most optimal microsphere formulation, with 20% Brij 98 as excipient, showed an initial in vitro burst around 20% and a sustained release over 28 days in a solubilizing release medium at 37 °C. The effect of addition of MgCO3, drug loading, and polymer blending on the release of fenretinide from PLGA microspheres was also investigated and observed to enhance the drug release. Two sustained release formulations, one incorporating 20% Brij 98 and the other incorporating 3% MgCO3 in the oil phase, were selected for dosing in Sprague-Dawley rats and compared to a single injection of an equivalent dose of fenretinide drug suspension. These two formulations were chosen due to their high encapsulation efficiency, high cumulative release, and desirable in vitro release profile. The drug suspension resulted in a higher initial release in rats compared to the polymeric formulations, however, sustained release was also observed beyond 2 weeks, which may be attributed to the physiological disposition of the drug in vivo. The two PLGA based test formulations provided the desired low initial burst of fenretinide followed by 4 weeks of in vivo sustained release.

Is the photometric method using acetone extracts to determine chlorophyll concentrations applicable to Mg‐deficient plants?

AbstractA conventional photometric method to determine chlorophyll concentrations in maize leaves was evaluated. It was tested whether in Mg‐deficient plant tissue the addition of MgCO3 during pigment extraction converts protoporphyrin IX into chlorophyll, falsifying concentration measurements. The non‐destructive N‐tester was used as a reference for the destructive chlorophyll determination. It is shown that both methods are valid for the determination of chlorophyll concentration in Mg‐deficient leaves.

Mild hydrothermal synthesis and structures of mixed‐valence iron phosphates: SrFe3(PO4)3 and the interesting Mg2+‐doped AFe3 (PO4)3 (A = Ba, Pb) in Fe2+ site

AbstractSeries of mixed valence monophosphates AFe3‐xMgx(PO4)3 [A = Sr(x = 0), Ba(x = 0.6), Pb(x = 0.6)] were synthesized by mild hydrothermal treatment at 210 °C. Refinements of single crystal X‐ray diffraction datas show all these compounds are isostructural. The attempts to make AFe3(PO4)3 (A = Ba, Pb) hydrothermally in the experiment were unsuccessful. However, the Mg‐doped homologues AFe2.4Mg0.6(PO4)3 (A = Ba, Pb) were synthesized with the addition of MgCO3 in the reactants as mineralizer. EDS and single crystal X‐ray data refinement indicated that the Mg2+ cations were doped in the Fe2+ sites of AFe2.4Mg0.6(PO4)3 (A = Ba, Pb). The influence of the Mg‐doping on the structure and the reason why the Mg doped in the Fe(II) site instead of A site was discussed from the point of view of the bond valence model.

Magnesium-silicate-hydrate cements for encapsulating problematic aluminium containing wastes

Low pH cement systems for encapsulating legacy nuclear industry wastes containing aluminium metal are being developed using blends of MgO and silica fume (SF). The rheology of the binary system is significantly improved by addition of sodium hexa-metaphosphate (Na-HMP) which reduces the required w/s ratio. The addition of MgCO3 further controls the initial pH of the cement system and sand filler reduces shrinkage cracking. The physical, chemical and mechanical properties of the optimised MgO/SF cement system in terms of pH, setting time, microstructure, compressive strength, flexural strength and heat of hydration are reported and compared to the PC/BFS blended system currently used for waste encapsulation. The optimised MgO/SF cement and PC/BFS cement are also compared by monitoring the volume of H2 generated from binder samples containing Al metal strips. Al metal was firmly bound into MgO/SF samples and H2 gas was not detected, indicating that any corrosion reactions were very limited. It is concluded that the MgO/SF cement system has significant potential for encapsulating certain types of problematic wastes containing Al metal and may have uses in a range of other applications.

Significance of CO2 donor on the production of succinic acid by Actinobacillus succinogenes ATCC 55618

BackgroundSuccinic acid is a building-block chemical which could be used as the precursor of many industrial products. The dissolved CO2 concentration in the fermentation broth could strongly regulate the metabolic flux of carbon and the activity of phosphoenolpyruvate (PEP) carboxykinase, which are the important committed steps for the biosynthesis of succinic acid by Actinobacillus succinogenes. Previous reports showed that succinic acid production could be promoted by regulating the supply of CO2 donor in the fermentation broth. Therefore, the effects of dissolved CO2 concentration and MgCO3 on the fermentation process should be investigated. In this article, we studied the impacts of gaseous CO2 partial pressure, dissolved CO2 concentration, and the addition amount of MgCO3 on succinic acid production by Actinobacillus succinogenes ATCC 55618. We also demonstrated that gaseous CO2 could be removed when MgCO3 was fully supplied.ResultsAn effective CO2 quantitative mathematical model was developed to calculate the dissolved CO2 concentration in the fermentation broth. The highest succinic acid production of 61.92 g/L was obtained at 159.22 mM dissolved CO2 concentration, which was supplied by 40 g/L MgCO3 at the CO2 partial pressure of 101.33 kPa. When MgCO3 was used as the only CO2 donor, a maximal succinic acid production of 56.1 g/L was obtained, which was just decreased by 7.03% compared with that obtained under the supply of gaseous CO2 and MgCO3.ConclusionsBesides the high dissolved CO2 concentration, the excessive addition of MgCO3 was beneficial to promote the succinic acid synthesis. This was the first report investigating the replaceable of gaseous CO2 in the fermentation of succinic acid. The results obtained in this study may be useful for reducing the cost of succinic acid fermentation process.

Preparation and characterization of porous ceramics prepared by kaolinite gangue and Al(OH)3 with double addition of MgCO3 and CaCO3

Porous ceramics were prepared from kaolinite gangue and Al(OH)3 with double addition of MgCO3 and CaCO3 by the pore-forming in-situ technique. The characterizations of porous ceramics were investigated by X-ray diffractometry, scanning electron microscopy, and mercury porosimetry measurements, etc. It is found that although the decomposition of MgCO3 and CaCO3 has little contribution to the porosity, the double addition of MgCO3 and CaCO3 strongly affects the formation of liquid phase, and then changes the phase compositions, pore characterization, and strength. The appropriate mode is the sample containing 1.17wt% MgCO3 and 1.17wt% CaCO3, which has high apparent porosity (41.0%), high crushing strength (53.5 MPa), high mullite content (76wt%), and small average pore size (3.24 μm).

The research on the effect of MgCO3 on the grain refinement in AZ31 magnesium alloy

AbstractThe effect of MgCO3 addition on the as‐cast microstructure of AZ31 magnesium alloy has been widely investigated. The results show that the average grain size of the α‐Mg grain in AZ31 magnesium alloy decreases from about 570 μm to 100 μm by the addition of 0.6 wt.% MgCO3 as gain refiner at 760°C. Based on the analysis of EDS, theoretical calculation of Ebind and Gibbs free energy, we esteem that grain refiner mechanism is mainly attributed to the generation of Al4C3, which can be serviced as nucleation site and restrain grain boundary from growing and transferring.

Soil Amendments Affecting Nickel and Cobalt Uptake by Berkheya coddii: Potential Use for Phytomining and Phytoremediation

Plants with inordinately high concentrations of heavy metals (‘hyperaccumulators’) can be used for phytoremediation (removal of contaminants from soils) or phytomining (growing a crop of plants to harvest the metals). Pot trials were used to investigate the effects of MgCO3, CaCO3, sulphur, chelating agents (NTA, DTPA, EDTA) and acid mine tailings on nickel and cobalt uptake by the South African nickel hyperaccumulator Berkheya coddii. Plants were grown in a nickel-rich ultramafic (‘serpentine’) soil diluted with pumice. Both MgCO3and CaCO3caused significant decreases in the uptake of both metals, as well as decreasing their solubility in the soil. After the addition of MgCO3,there was a significant increase in soil pH, so the reduction in plant-metal uptake could not be solely attributed to the action of magnesium alone. Since CaCO3had no significant effect on soil pH, this indicated that calcium inhibits the uptake of both cobalt and nickel. All three chelating agents caused a significant reduction in plant uptake of nickel, despite increasing the solubility (plant availability) of these elements in the soil. Cobalt uptake was unaffected. Sulphur, and the addition of acid mine tailings, caused a highly significant increase in nickel and cobalt uptake, relative to the controls. Sulphur could be used as a low-cost soil amendment to enhance the metal uptake of crops grown on ultramafic soils. Thus, land management procedures would enhance phytoremediation and phytomining operations for nickel and cobalt.