Higher NaHCO3 Concentration Research Articles

U(VI) sorption by CTAB/Bent–MOF-74 from various carbonate solutions

CTAB/Bent-MOF-74 was synthesized via hydrothermal method to investigate its U(VI) sorption in carbonate solutions. Generally, CTAB/Bent-MOF-74 (∼87.6 mg·g−1) showed better sorption capacity than CTAB/Bent-MOF-71 (∼64.2 mg·g−1) and CTAB/Bent-CS-35 (∼81.4 mg·g−1) in U(VI)-Cl coexist carbonate solutions when pH = 8.0, [NaHCO3] =2 mmol·L−1, [NaCl] =0.1 mol·L−1 and [U(VI)] =50 mg L−1. The competitive sorption between HCO3−/CO32−, OH−, halide ions and U(VI) complexes ions as well as the weakened electrostatic attraction decreased the composite's uranium sorption efficiency and capacity at high pHinitial, NaHCO3, phosphate, Ca/Mg and halide ions concentrations. The pseudo-second-order kinetics and Langmuir models indicated a monolayer homogeneous chemisorption process. Besides, 0.1mol·L−1 HCl shows the highest desorption efficiency among the selected desorbents, and the sorption rate is still high even after four times of desorption. In particular, the decreasing inhibitory capacity of the halide ions was on the order of I−, F−, Br−, Cl−. Characterization analyzes confirmed the good structural stability and Br anion exchange as well as the -OH/-COOH coordination and electrostatic attraction, which could be the predominant sorption mechanisms of U(VI) by CTAB/Bent-MOF-74. The results provided theoretical references for understanding the uranium sorption in natural uranium-containing water and designing potential uranium-extracting materials.

Pyruvate orthophosphate dikinase is required for the acclimation to high bicarbonate concentrations in Phaeodactylum tricornutum

The model marine diatom P. tricornutum possesses efficient CO2-concentrating mechanisms (CCMs) involving the bicarbonate transport and the rapid inter-conversion of HCO3− and CO2, and it has a complete set of enzymes essential for biochemical CCM C4 pathway. However, the role of potential C4 pathway in the diatom is still controversial. Based on the analysis of previously published proteome and transcriptome data in P. tricornutum, the expression of pyruvate orthophosphate dikinase (PPDK), a key enzyme generating the primary acceptor for bicarbonate fixation in C4 pathway, was upregulated in long-term high CO2-selected populations. In our study, P. tricornutum PPDK (PtPPDK) transcript abundance was higher with short-term treatment of high NaHCO3 concentrations and overexpression of PtPPDK resulted in a cell density increase of 5–16 % from day 2 to 8. Knockdown (KD) or knockout of PtPPDK inhibited the growth and the maximal photosystem II electron transport rate, and the inhibited growth became more and more evident with the increasing NaHCO3 concentration from 1 to 8 mM in PtPPDK KD lines. Furthermore, elevating NaHCO3 from 1 to 16 mM dramatically decreased the cell density both in wild-type and PtPPDK mutants, suggesting that 1 mM NaHCO3 is enough for the photosynthesis carbon assimilation. PtPPDK was localized in the plastid stroma by eGFP fusion protein analysis at 2 mM NaHCO3, while PtPPDK-eGFP fluorescence was observed both in the stroma and periplasmic space at higher NaHCO3. It is suggested that PPDK is necessary for consuming excessive inorganic carbon (Ci) both from the plastid and extracellular environment to maintain pH homeostasis, indicating a potential function of adapting to high Ci concentrations.

Sustained-Release and pH-Adjusted Alginate Microspheres-Encapsulated Doxorubicin Inhibit the Viabilities in Hepatocellular Carcinoma-Derived Cells.

The objective of this study aimed to develop biodegradable calcium alginate microspheres carrying doxorubicin (Dox) at the micrometer-scale for sustained release and the capacity of pH regulatory for transarterial chemoembolization. Ultrasonic atomization and CaCl2 cross-linking technologies were used to prepare the microspheres. A 4-by-5 experiment was first designed to identify imperative parameters. The concentration of CaCl2 and the flow rate of the pump were found to be critical to generate microspheres with a constant volume median diameter (~39 μm) across five groups with different alginate: NaHCO3 ratios using each corresponding flow rate. In each group, the encapsulation efficiency was positively correlated to the Dox-loading %. Fourier-transform infrared spectroscopy showed that NaHCO3 and Dox were step-by-step incorporated into the calcium alginate microspheres successfully. Microspheres containing alginate: NaHCO3 = 1 exhibited rough and porous surfaces, high Young’s modulus, and hardness. In each group with the same alginate: NaHCO3 ratio, the swelling rates of microspheres were higher in PBS containing 10% FBS compared to those in PBS alone. Microspheres with relatively high NaHCO3 concentrations in PBS containing 10% FBS maintained better physiological pH and higher accumulated Dox release ratios. In two distinct hepatocellular carcinoma-derived cell lines, treatments with microspheres carrying Dox demonstrated that the cell viabilities decreased in groups with relatively high NaHCO3 ratios in time- and dose-dependent manners. Our results suggested that biodegradable alginate microspheres containing relatively high NaHCO3 concentrations improved the cytotoxicity effects in vitro.

NaHCO3/Na2CO3 as an inhibitor of chloride-induced mild steel corrosion in cooling water: Electrochemical evaluation

This study systematically investigated the inhibition mechanism of NaHCO3 for mild steel corrosion in a 0.02M naturally aerated NaCl solution at 40°C (simulating cooling water) and the critical bicarbonate/chloride molar ratio (RC) using visual observations, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. The corrosion mechanism of an anodic passive film formed with 0.20–0.40M NaHCO3 (RC=10) was controlled by a combination of passivation, diffusion, and charge transfer processes. Electrochemical impedance spectroscopy results showed that, compared to 0.20–0.24M NaHCO3, a higher NaHCO3 concentration may affect the stability of the passive film. A higher chloride concentration of 0.08M achieved by a higher concentration cycle in the cooling water system resulted in a lower RC value of 7.5 for NaHCO3. Both NaHCO3 and Na2CO3 showed an identical corrosion mechanism; moreover, the inhibitory effect of Na2CO3 was not dependent on its alkaline pH. Taken together, these findings show the remarkable potential of NaHCO3/Na2CO3 as a commercially available, comparatively cheap, and environmentally acceptable (i.e., no organic pollution, toxicity, or eutrophication risks after discharge) corrosion inhibitor for mild steel in cooling water systems.

Assessing the Influence of Saline and Alkaline Environments in the Preservation of Pampean Diatoms: An Experimental Approach

Diatom dissolution is controlled by environmental conditions prevailing during fossilization. In Pampean shallow lakes, diatom dissolution showed important correlations with gradients of salinity, pH, carbonate, and bicarbonate, being these the most probable causes of the observed shifts in Holocene assemblages preservation. In the present contribution, a series of experiments were conducted in order to demonstrate the effect that physical-chemical lake characteristics exert on Pampean diatom assemblages preservation. Three experimental assemblages were subjected to the effect of three concentrations of two salts, NaCl (0.6, 1.2 and 3M) and NaHCo3 (0.6, 0.9, and 1.2M), and two pH values (7 and 10). Aliquots of the experimental solutions were removed once each five days for 20 days, and analyzed for changes in dissolved silica concentration (SiDi), relative and absolute abundances of diatoms, and dissolution indices (DDI) based on the target taxon Cyclotella meneghiniana. All the experimental solutions increased the SiDi significantly, particularly since day 10. These increased SiDi values were accompanied by significant changes in the DDI, which reached maximum values at pH 10, and by evidence of dissolution observed in SEM images, whereas no significant changes in relative or absolute abundances of diatoms were registered. These experimental results demonstrated the impact that water chemistry can exert on diatom dissolution in Pampean shallow lakes, even during short-term exposures. Given the naturally high pH, NaCl and NaHCo3 concentrations characteristic of many of these lakes, these experimental findings can be confidently extrapolated to the interpretation of the dissolution trends found in modern and fossil sedimentary assemblages.

The Influence of Processing Parameters on the Mitigation of Deoxynivalenol during Industrial Baking.

Deoxynivalenol (DON), a frequent contaminant of flour, can be partially degraded by baking. It is not clear: (i) How the choice of processing parameter (i.e., ingredients, leavening, and baking conditions) affects DON degradation and thus (ii) how much DON can be degraded during the large-scale industrial production of bakery products. Crackers, biscuits, and bread were produced from naturally contaminated flour using different processing conditions. DON degradation during baking was quantified with the most accurate analytical methodology available for this Fusarium toxin, which is based on liquid chromatography tandem mass spectrometry. Depending on the processing conditions, 0–21%, 4–16%, and 2–5% DON were degraded during the production of crackers, biscuits, and bread, respectively. A higher NaHCO3 concentration, baking time, and baking temperature caused higher DON degradation. NH4HCO3, yeast, vinegar, and sucrose concentration as well as leavening time did not enhance DON degradation. In vitro cell viability assays confirmed that the major degradation product isoDON is considerably less toxic than DON. This proves for the first time that large-scale industrial baking results in partial detoxification of DON, which can be enhanced by process management.

Effect of Carbonate on the Migration Behavior of Strontium in Compacted Bentonite

ABSTRACTThe apparent diffusion coefficients of strontium in compacted bentonites were investigated at various concentrations of NaHCO3. Purified sodium bentonite Kunipia-F® was compacted with a jig into cylindrical pellets 10 mm in diameter and 10 mm high with dry densities of 1.0 to 1.6 Mg/m3. Each bentonite pellet was inserted into an acrylic resin column and saturated with carbonated water containing 0.1 to 1.0 M NaHCO3 for more than 1 month. The face of the bentonite specimen was spiked with 5 μL of 1.0 M SrCl2 tracer solution. After a few weeks, the strontium diffusion profiles were measured by inductively coupled plasma-mass spectrometry. The apparent diffusion coefficients of strontium decreased slightly with increasing dry density. NaHCO3 concentrations of 0.5 M decreased the apparent diffusion coefficients of strontium by half at a dry density of 1.0 Mg/m3 and quarter at 1.6 Mg/m3. At a higher NaHCO3 concentration of 1.0 M, no strontium diffusion profile was observed, whereas white precipitate was observed on the face of the bentonite specimen where it was spiked with strontium. This white precipitate could be strontianite, which is strontium carbonate. Diffusion experiments using cesium were carried out for comparison, and the presence of carbonate had no effect on the apparent diffusion coefficient.

Fabrication of carbonate apatite blocks from octacalcium phosphate blocks through different phase conversion mode depending on carbonate concentration

Carbonate apatite (CO3Ap) is an inorganic component of mature bone and is used as bone substitute instead of autografts. Recently, 100% pure CO3Ap granules formed from calcium carbonate via a dissolution-precipitation reaction have been used as a clinical precursor for bone. In this study, the feasibility of fabricating blocks of CO3Ap from blocks of octacalcium phosphate (OCP), which is an analog of the bone composition and serves as a precursor for bone, was investigated by immersion in NaHCO3. The macroscopic structure of the OCP block was retained upon conversion to CO3Ap. In addition, as the NaHCO3 concentration increased from 0.0 to 2.0 mol/L, the carbonate content increased in the resulting CO3Ap, reaching ≈ 14 wt% at maximum NaHCO3 concentration. Moreover, the morphology of the CO3Ap crystals varied as the NaHCO3 concentration increased up to 0.5 mol/L: they were pseudomorphic plate-like when the NaHCO3 concentration was low but formed particles ranging ~ 10 nm in size at high NaHCO3 concentrations. The different phase transformation modes depended on NaHCO3 concentrations closely related to CO3Ap crystal morphology and were associated with a decrease in the mechanical strength of the block.

Electrochemical CO2 reduction to formate at indium electrodes with high efficiency and selectivity in pH neutral electrolytes

Electrochemical reduction of CO2 is promising for a bio-based economy as it combines utilization of CO2 as feedstock and provides a pathway for the utilization and (temporary) storage of electric energy. Among different products formate (HCOO-) can be produced with high rates and selectivity using indium as electrocatalyst. This can be achieved at mild biocompatible reaction conditions, e.g. ambient temperature, ambient pressure and neutral pH. Formate can serve as a source of carbon and energy for the biosynthesis of energy carriers or chemicals. However, the in situ interfacing of electrochemical CO2 reduction and biosynthesis creates challenges for electrochemical engineering. It is demonstrated that the electrode potential is the main steering parameter affecting the columbic efficiency, selectivity and rate of formate production in NaHCO3 electrolyte solution at biocompatible conditions. Coulombic efficiencies and formate production rates of 94.5 ± 2% and 0.136 ± 0.016 mmol h-1 cm-2 (at -2.2 vs. Ag/AgCl and ĸ = 10 mS cm-1), respectively, were achieved. Further, increasing the conductivity using inert electrolytes can enhance formate space-time yields up to 0.254 ± 0.031 mmol h-1 cm-2. Surprisingly, high NaHCO3 concentrations do not further increase formate production which supports that HCO3- is not electrochemically converted but only acting as CO2/H+ reservoir. Based on kinetic modeling insight on the inter-conversion of the carbonaceous species by CO2 sparging of the electrolyte solution is provided. Importantly, the influence of O2 on the electrochemical CO2 reduction was revealed to be marginal. This study, providing principles on the engineering of electrochemical CO2 reduction to formate for future interfacing to biosynthesis, demonstrates its feasibility to become technologically relevant.

Enhanced gelation of chitosan/β-sodium glycerophosphate thermosensitive hydrogel with sodium bicarbonate and biocompatibility evaluated

The application of chitosan/β-sodium glycerophosphate (β-GP) thermosensitive hydrogel has been limited by the relatively slow gelation, weak mechanical resistance and poor cytocompatibility. In this study, sodium hydrogen carbonate (NaHCO3) was applied with β-GP as gel agents to produce high-strength hydrogel. The hydrogels prepared with high NaHCO3 concentration or more gel agents showed shorter gelation time, better thermostability, drastically enhanced resistance in compression. Meanwhile, the hydrogels presented obvious porous structures and excellent biocompatibility to HUVEC and NIH 3T3 cultured in vitro with higher NaHCO3 concentration and moderate concentration of β-GP. Overall, appropriate concentration of β-GP combined with NaHCO3 can be a good gel regent to improve properties of chitosan thermosensitive hydrogels.

Discovery of two novel highly tolerant NaHCO3 Trebouxiophytes: Identification and characterization of microalgae from extreme saline–alkali soil

Through identifying and characterizing microalgae from extreme saline–alkaline soils (pH>10, Songnen Plain, China), which are rich in carbonate (NaHCO3 and Na2CO3), we aimed to explore the microalgae carbonate stress mechanism and acquire possible extreme saline–alkali microalgae as genetic resources for crop improvement and cultivation. We identified the microalgae based on optical microscopy (OM), scanning electron microscopy (SEM), and 18S rRNA sequence analysis. We determined strains' salt-tolerance abilities with a range of NaCl and NaHCO3 concentrations. The intracellular ultrastructure was observed with transmission electron microscopy (TEM) after NaCl and NaHCO3 treatments. We observed strain growth response by detecting dry weight and chlorophyll-a (chl-a) content at different NaHCO3 concentrations. We identified 20 novel strains of microalgae as 13 genera based on morphological and sequence analyses, and classified them into six groups by class level, including Chlorophyceae, Trebouxiophyceae, Ulvophyceae, Bacillariophyceae, Xanthophyceae, and Bangiophyceae; Chlorophyta occupied the most dominant algal groups. Most isolates possessed saline tolerance, especially two strains in the class Trebouxiophyceae, which could grow on solid media with high NaHCO3 concentrations. The TEM results showed cell walls of the two Trebouxiophyte strains (JB6 and 17) with more integrity than reference Chlorella, and a larger number of starch grains were accumulated under 300mM NaCl and NaHCO3. Further analysis showed that the dry weights and chl-a contents of two Trebouxiophyte strains were much better than the reference Chlorella in liquid media with different concentrations of NaHCO3. The two Trebouxiophyte strains had optimal growth at 100 and 400mM NaHCO3 concentrations, and both survived at 1000mM NaHCO3. The results revealed that the two Trebouxiophyte strains showed extreme tolerance to high concentrations of NaHCO3.

Methyl Orange Degradation on TiO<sub>2</sub> and Mixture of TiO<sub>2</sub> and HZSM-5 in NaHCO<sub>3</sub> Solution

Methyl orange decoloration was conducted in the solution containing NaHCO3. TiO2 and the mixture of TiO2 and HZSM-5 were used as the photocatalysts. The addition of TiO2 greatly changed adsorption of methyl orange in solutions containing different concentration of NaHCO3. The existence of NaHCO3 can improve photocatalytic degradation of the dye under UV irradiation in the solution containing TiO2. As high as 55% decoloration of the dye occurred in the solution containing 1.0 mol/l NaHCO3. When NaHCO3 concentration was lower than 0.08 mol/l, adsorption of the dye was fairly weak on the mixture. At the same time, decoloration of the dye deceased with increasing NaHCO3 concentration. When NaHCO3 concentration was high, adsorption and decoloration of the dye were better at higher NaHCO3 concentration.

Denitrification with methanol in the presence of high salt concentrations and at high pH levels

In the combined ion exchange/biological denitrification process for nitrate removal from ground water, in which nitrate is removed by ion exchange, the resins are regenerated in a closed circuit by a biological denitrification reactor. This denitrification reactor eliminates nitrate from the regenerant. Methanol is used as electron donor for biological denitrification. To obtain sufficient regeneration of the resins within a reasonable time, high NaCl or NaHCO3 concentrations (10–30 g/l) in the regenerant are necessary. High NaHCO3 concentrations affected the biological denitrification in three ways: a) a slight decrease in denitrification capacity (30%) was observed; b) the yield coefficient and CH3OH/NO3-−N ratio decreased. When high NaHCO3 concentrations (above 10g NaHCO3/l) were used, the yield coefficient was 0.10–0.13 g VSS/g NO3-−N and the CH3OH/NO3-−N ratio was 2.00–2.03 g/g; c) high NaHCO3 concentrations influenced nitrite production. Nitrite is an intermediate product of biological denitrification and with rising NaHCO3 concentrations nitrite accumulation was suppressed. This was explained by the effect of high NaHCO3 concentrations on the pH in the microenvironment of the denitrifying organisms. High NaCl concentrations also resulted in a slight decrease in denitrification capacity, but the second and third effects were not observed in the presence of high NaCl concentrations.