Effect Of HCO3 Research Articles

Corrosion behavior on carbon steel in a simulated soil solution under the interaction effect of chloride and bicarbonate ions

The effect of HCO3− and Cl− on the corrosion behavior of Q345 carbon steel in soil simulated solutions was investigated through electrochemical and surface characterizations. The results show that the sample behaves with active dissolution state in low concentration of Cl− solution while pseudo passivation of sample is observed in high concentration of Cl− solution. However, in solutions containing low concentration of HCO3−, the addition of high concentration Cl− does not result in the pseudo passivation of sample due to the formation of discontinuous film, which increases the corrosion rate. In addition, in solution containing high concentration of HCO3−, the addition of high concentration Cl− leads to much higher increase of corrosion rate. The deep corrosion pit is observed on the matrix due to the rapid rupture of FeCO3 film and the sufficient development of pitting.

Inactivation of fungal spores in water with peracetic acid: Efficiency and mechanism

In recent years, peracetic acid (PAA) has been widely used in sewage disinfection due to its strongly sterilizing capacity and less toxic by-products production. However, there was no studies on the inactivation kinetics and mechanism of fungal spores in water by PAA as well as their regrowth. The inactivation efficiency and mechanism of Aspergillus niger and Aspergillus flavus by PAA was illustrated in this study. The results showed that the inactivation of fungal spores fitted to the delayed Chick–Watson model well. The inactivation rate constants were 0.038 and 0.033 L mg−1 min−1, respectively. The effects of pH value and humic acid concentration on the inactivation efficiency were negative and the effect of temperature was positive, while the effect of HCO3− and Cl− on the disinfection of fungal spores could be negligible. The results of flow cytometric measurements, morphological observation and the leakage of intracellular substances indicated that the inactivation of fungi by PAA was attributed to the penetration of cell membranes rather than the damage of cell membranes. PAA was found to be effective for the inactivation of fungal spores, but was less effective than several traditional disinfectants (Cl2, ClO2) under the same condition. Furthermore, the regrowth of fungal spores after disinfection with PAA was also evaluated. The regrowth of fungal spores that after 1–3 log inactivated in the R2A medium within 5 days was observed, but the regrowth of completely inactivated fungal spores in R2A and in trace element solution was negligible. This study provides the valuable information for the application of PAA in the control of fungal pollution.

Reasons Analysis on Corrosion Perforation of L245 Pipeline from Interior Wall

The leakage accident of corrosion perforation occurred in the L245 oil pipeline. After pipe replacement,the defects were analyzed by means of macro analysis, corrosion product analysis, medium composition analysis, chemical composition analysis, mechanical property test and SEM. The results showed that the corrosion perforation was caused by local corrosion, and the synergistic effect of HCO3- and Cl- in transportation medium was the main cause of local corrosion.

The photocatalytic reduction of NO3− to N2 with ilmenite (FeTiO3): Effects of groundwater matrix

This work analyzes the role of natural groundwater, as well as the effect of HCO3−, Ca2+, Mg2+, K+, SO42- and Cl− concentrations, upon the photocatalytic nitrate reduction using ilmenite as catalyst and oxalic acid as hole scavenger. The nitrate removal and the selectivity towards N2 are significantly limited compared to previous experiments using ultrapure water matrix. Calcium (Ca2+), bicarbonate (HCO3−) as well as pH are claimed as the major controlling factors related to the process yield. Thus, Ca2+ promotes the formation of insoluble oxalate microcrystals, reducing the amount of hole scavenger available. The presence of HCO3− leads to a steeply increase in the pH value, favoring the adsorption onto the ilmenite surface of ions OH−instead of NO3−, NO2− and C2O42. The aforementioned issues are overcome by working with C2O42−/NO3− ratio well above the stoichiometric one, that also maintains the pH value in an acid range. A completed depletion of the starting NO3−, the no detection of either NO2− or NH4+ in the aqueous phase, and a selectivity towards N2 above 95% were achieved using two times the stoichiometric dose.

Effect of HCO3- on Stress Corrosion Cracking Behavior of X90 Pipeline Steel

Effect of HCO3- on Stress Corrosion Cracking Behavior of X90 Pipeline Steel

Kinetic and thermodynamic study of oxidative degradation of acid yellow 17 dye by Fenton-like process: Effect of HCO3−, CO32−, Cl− and SO42− on dye degradation

We report here the degradation of AY-17 dye using Fenton-like process (H 2 O 2 /Fe 3+ ). The maximum degradation (83%) of AY17 dye is achieved at pH 3 in 60 min, with optimum concentrations of AY 17 (0.06 mM), H 2 O 2 (0.9 mM), and Fe 2+ (0.06 mM). The scavenging effects of HCO 3 − , CO 3 2− , Cl − and SO 4 2− on dye degradation are also examined. The activation energy ( E a ), activation enthalpy (rH * ), and activation entropy (rS * ) are calculated for the dye degradation using pseudo-first-order kinetics at various temperature. KEY WORDS : Acid Yellow 17, H 2 O 2 /Fe 3+ , Fenton-like process, Oxidative degradation, Scavenging effects Bull. Chem. Soc. Ethiop. 2019 , 33(2), 243-254. DOI: https://dx.doi.org/10.4314/bcse.v33i2.5

An electrochemical study on the effect of bicarbonate ion on the corrosion behaviour of carbon steel in CO2 saturated NaCl solutions

The electrochemical study on the effect of HCO3− on the corrosion behaviour of carbon steel in CO2 saturated NaCl solutions was investigated through mathematical calculation of impedance plots and potentiodynamic polarization. Results reveal that a competitive adsorption between HCO3−/Cl− exists, and HCO3− is able to reduce and/or replace the adsorption of Cl− on carbon steel surfaces with the elevation of HCO3− concentration. In addition, at the certain condition (CO2-saturated solution containing 0.1 M Cl−), carbon steel tends to passivate when HCO3− concentration reaches 0.5 M. However, pitting can be triggered in 0.2 M HCO3− concentration. The findings of this work spot light on the understanding of many parameters related to this process, which is of great significance to prevent the underlying corrosion failure and prolong the lifespan of carbon steel pipelines in the service environment.

Effect of HCO3− concentration in groundwater on TiO2 photocatalytic water purification

Evaluation of the effects of major components of groundwater systems on photocatalytic activity is essential for the development of commercial photocatalytic water purification systems. In this work, we have probed the effects of bicarbonate ion (HCO3−) on the photocatalytic activity of a TiO2 ceramic photocatalyst. Two brands of mineral water, Evian and Contrex, which contain high concentrations of alkaline earth metal ions Mg2+ and Ca2+, were used as models for groundwater. The degradation rate of formic acid was used as an index of photocatalytic activity. The rate of HCO3− degradation and changes in the type and concentration of the HCO3− counterion with the progress of photocatalytic reaction were also observed. After the completion of 15 cycles of 8 h of photocatalytic reaction (total run time 120 h), the surface of the photocatalyst and precipitates formed on it were analyzed by means of X-ray diffraction analysis, Raman spectrometry, scanning electron microscopy, and energy dispersive X-ray spectrometry. We found that the photocatalytic activity was reduced with increasing HCO3− concentration, irrespective of the type of counterion present. In addition, photocatalytic activity remained unchanged despite an increase in accumulation of the precipitate, which we identified as CaCO3, on the photocatalyst surface with the progress of experimental cycles. We also observed that the concentration of formic acid and HCO3− were decreased with photocatalysis when Ca2+ was a counterion, however, no effect in presence of other metal ions, Na+, K+ or Mg2+, was observed. These results show that bicarbonate ion was involved in the photocatalytic reaction when Ca2+ was the counterion, and as a result, the photocatalytic degradation rate of formic acid was decreased and CaCO3 precipitate was formed.

Bicarbonate Inhibits Bacterial Growth and Biofilm Formation of Prevalent Cystic Fibrosis Pathogens.

We investigated the effects of bicarbonate on the growth of several different bacteria as well as its effects on biofilm formation and intracellular cAMP concentration in Pseudomonas aeruginosa. Biofilm formation was examined in 96-well plates, with or without bicarbonate. The cAMP production of bacteria was measured by a commercial assay kit. We found that NaHCO3 (100 mmol l-1) significantly inhibited, whereas NaCl (100 mmol l-1) did not influence the growth of planktonic bacteria. MIC and MBC measurements indicated that the effect of is bacteriostatic rather than bactericidal. Moreover, NaHCO3 prevented biofilm formation as a function of concentration. Bicarbonate and alkalinization of external pH induced a significant increase in intracellular cAMP levels. In conclusion, impedes the planktonic growth of different bacteria and impedes biofilm formation by P. aeruginosa that is associated with increased intracellular cAMP production. These findings suggest that aerosol inhalation therapy with solutions may help improve respiratory hygiene in patients with cystic fibrosis and possibly other chronically infected lung diseases.

Effect of HCO3− on electrochemical kinetics of carbon steel corrosion in CO2-saturated brines

The effect of HCO3−(aq) on CO2 corrosion of carbon steel was investigated in deaerated 3.5 wt% NaCl solutions at 30 °C from pH 3.96 to 7.15. In the CO2-saturated solutions, the pH was adjusted with different HCO3−(aq) concentrations, c[HCO3−(aq)]. The corrosion rate decreased by a factor of 2 as the pH and c[HCO3−(aq)] increased. The cathodic current density during polarization increased at higher pH with higher c[HCO3−(aq)], indicating that HCO3−(aq) acted as an additional hydrogen source for the hydrogen evolution reaction. As the pH increased, the active dissolution regions displayed similar anodic Tafel slopes and suggested a modified Bockris mechanism for the Fe oxidation reaction. The exchange current densities for the half reactions were calculated to study kinetics of the anodic and cathodic half reactions independently. The anodic exchange current density (j0,a) increased by one order of magnitude in the presence of CO2, indicating the involvement of CO2(aq) in the Fe oxidation reaction. As the pH and c[HCO3−(aq)] increased, the cathodic exchange current density (j0,c) decreased by a factor of 50 because the increase in j0,c[HCO3−(aq)] was not high enough to compensate the decline from the other hydrogen sources, especially j0,c[H+(aq)]; and j0,a decreased by a factor of 2.4 because HCO3−(aq) may have competed with CO2(aq) for the surface coverage and the increase in j0,a[HCO3−(aq)] could not compensate the decrease in j0,a[CO2(aq)]. It suggests that the reaction rate constant of HCO3−(aq) was smaller than CO2(aq) for the anodic half reaction and was smaller than H+(aq) for the cathodic half reaction. The XPS results verified that the corrosion products transitioned from iron carbonate to hydroxide as the pH increased while iron carbonate remained the major product. As the pH increased with HCO3−(aq), a second time constant was observed at lower frequencies of the electrochemical impedance spectroscopy (EIS) results.

Effect of HCO3- level on the accuracy of NoSAS screening for obstructive sleep apnea hypopnea syndrome

Objective: To evaluate the effect of arterial blood HCO3- level on the accuracy of NoSAS questionnaire screening for obstructive sleep apnea hypopnea syndrome (OSAHS). Methods: The hospitalized patients with suspected OSAHS were recruited from March 2016 to December 2017 in the First Affiliated Hospital of Guangzhou Medical University. NoSAS scores, blood gas analysis and polysomnography (PSG) were performed in these patients. Patients were divided into non OSAHS group and mild, moderate and severe OSAHS group according to the PSG results. According to the NoSAS questionnaire score, the patients were divided into OSAHS high-risk group and low risk group. The correlation between arterial blood HCO3- level and apnea hypopnea index (AHI) was analyzed. The receiver operating characteristic (ROC) curve was plotted to analyze the accuracy of HCO3- prediction OSAHS. Predictive parameters(sensitivity, specificity, positive and negative predictive values)for NoSAS scores and HCO3- level were calculated. Results: A total of 243 patients with suspected OSAHS were included, including 186 males (76.5%), 57 females (23.5%), age (49±13) years, body mass index (BMI) (26.9±4.4) kg/m2, and neck circumference (38.6±4.5) cm. The HCO3- level was positively correlated with AHI (r=0.206, P=0.001). The proportion of patients with HCO3- level ≥26 mmol/L in non-OSAHS group was lower than that in OSAHS group (13.0% vs 34.5%, P=0.004); the proportion of patients with HCO3- level ≥26 mmol/L in severe OSAHS group was higher than that in mild OSAHS group (37.7% vs 15.0%, P=0.008), and there was no difference in the ratio of patients with severe OSAHS and moderate OSAHS (37.7% vs 35.3%, P=0.767). The specificity of OSAHS predicted by HCO3- level 25 and 26 mmol/L was 69.6% and 87.0%, respectively. With the NoSAS score of 8 or 7 as cutoffs for analysis, the sensitivity for OSAHS was 61.9% and 79.2%, the specificity for OSAHS was 57.4% and 40.4%, respectively. With the addition of HCO3- level ≥ 26 mmol/L to the NoSAS score ≥ 7, the specificity for OSAHS improved to 93.6%, while the sensitivity decreased to 27.4%. Conclusion: Combined with the arterial blood HCO3- level, the specificity of the NoSAS questionnaire increases and the sensitivity decreases.

Reduction of Gibbs free energy and enhancement of Methanosaeta by bicarbonate to promote anaerobic syntrophic butyrate oxidation

Bicarbonate (HCO3−) has been extensively researched as a buffer in anaerobic digestion. The effect of HCO3− concentration on syntrophic butyrate oxidation process was evaluated by batch culturing of anaerobic activated sludge, and the mechanism was further revealed by the changes of Gibbs free energy (ΔG) and the interspecies transfers of electron and proton. The results showed that butyrate degradation rate was enhanced by 32.07% when the supplement of HCO3− increased from 0 to 0.20 mol/L. However, methane production and acetate degradation were strongly inhibited by HCO3− more than 0.10 mol/L. More function of HCO3− was found as 1) decreasing the ΔG of syntrophic methanogenesis of butyrate while increasing the ΔG of methanogenesis of acetate, 2) enriching M. harundinacea and M. concilii, 3) increasing the diffusion rate of protons between the syntrophic consortia. This work would increase the anaerobic digestion efficiency by enhancing the interaction of the syntrophic consortia.

Effect of HCO3− Concentration on the Corrosion Behaviour of X80 Pipeline Steel in Simulated Soil Solution

Effect of HCO3− Concentration on the Corrosion Behaviour of X80 Pipeline Steel in Simulated Soil Solution

Degradation of humic acid using hydrogen peroxide activated by CuO-Co3O4@AC under microwave irradiation

To investigate the degradation of humic acid (HA) in a CuO-Co3O4@AC/H2O2 system under microwave irradiation, a catalyst (CuO-Co3O4@AC) was prepared and characterized. The effects of several reaction parameters, such as the microwave temperature, initial pH, H2O2 concentration, catalyst dosage and inorganic anions (HCO3- and Cl-) were investigated, and the synergetic effect of hydrogen peroxide among MW, AC and metal oxides was explored. The results indicated that cobalt and copper were supported on activated carbon and existed as Co3O4 and CuO. The removal efficiency of HA and TOC reached 88% and 71%, respectively, with 100 mg/L HA, 80°C, 9.8mM H2O2 and 0.5g/L catalyst under 60min of microwave irradiation. The existence of HCO3- and Cl- had an inhibitory effect on the degradation of HA, and the effect of HCO3- was more evident. Quenching experiments and EPR tests confirmed that OH and O2− were the main free radical species, and XPS analysis showed that the species present on AC were Co (II), Co (III) and Cu(II), which can activate H2O2 to produce OH and O2−.

Corrosion mechanisms of Zn(Mg,Al) coated steel: The effect of HCO3− and NH4+ ions on the intrinsic reactivity of the coating

The effect of NH4+ and/or HCO3− ions on the reactivity of hot dip galvanized steel and Zn - 3.7wt. % Mg–3wt. % Al coated steel in aqueous solutions containing Cl− was studied by direct measurement of the elemental dissolution rates of Zn, Mg and Al by atomic emission spectroelectrochemistry at open circuit potential and under alternating anodic (0.95V vs SCE) and cathodic (-1.15V vs SCE) potentiostatic pulses. The anodic reactivity of ZnMgAl coating was higher compared to a standard hot dip galvanized coating in all electrolytes. Mg rich phases were selectively dissolved. NH4+ increased the anodic reactivity of Zn in both coatings, suppressed the accumulation of zinc corrosion products, and inhibited Al dissolution at open circuit. HCO3− increased the accumulation of insoluble zinc corrosion products as well as the anodic reactivity. The cathodic current on the fresh surface of ZnMgAl in 0.1M NaCl and in the mixture of 0.1M NH4Cl and 0.1M NaHCO3 was the same but cathodic dissolution of Al was higher in the mixed electrolyte. A series of alternating anodic and cathodic potentiostatic pulses demonstrated that the preliminary anodic polarization modified the following response of ZnMgAl on the cathodic pulse: the cathodic Al dissolution was significantly delayed and the cathodic current increased in mixed electrolyte. The cathodic current in NaCl was not affected by the preliminary anodic polarization. The effect was interpreted using a hypothesis of the formation of low soluble Mg carbonates during anodic polarization. Layered double hydroxides were not detected on ZnMgAl coatings after short experiments in mixed electrolyte. In contrast, Mg(OH)2, which is thermodynamically less stable at slightly alkaline pH, was detected. This indicates the importance of kinetic factors for the formation of corrosion products during the first stages of corrosion.

Stress corrosion cracking of X80 pipeline steel exposed to high pH solutions with different concentrations of bicarbonate

Susceptibilities to stress corrosion cracking (SCC) of X80 pipeline steel in high pH solutions with various concentrations of HCO 3 − at a passive potential of −0.2 V vs. SCE were investigated by slow strain rate tensile (SSRT) test. The SCC mechanism and the effect of HCO 3 − were discussed with the aid of electrochemical techniques. It is indicated that X80 steel shows enhanced susceptibility to SCC with the concentration of HCO 3 − increasing from 0.15 to 1.00 mol/L, and the susceptibility can be evaluated in terms of current density at −0.2 V vs. SCE. The SCC behavior is controlled by the dissolution-based mechanism in these circumstances. Increasing the concentration of HCO 3 − not only increases the risk of rupture of passive films but also promotes the anodic dissolution of crack tips. Besides, little susceptibility to SCC is found in dilute solution containing 0.05 mol/L HCO 3 − for X80 steel. This can be attributed to the inhibited repassivation of passive films, manifesting as a more intensive dissolution in the non-crack tip areas than at the crack tips.

Normal mouse intestinal mucus release requires cystic fibrosis transmembrane regulator–dependent bicarbonate secretion

The mechanisms underlying mucus-associated pathologies in cystic fibrosis (CF) remain obscure. However, recent studies indicate that CF transmembrane conductance regulator (CFTR) is required for bicarbonate (HCO3-) transport and that HCO3- is critical for normal mucus formation. We therefore investigated the role of HCO3- in mucus secretion using mouse small intestine segments ex vivo. Basal rates of mucus release in the presence or absence of HCO3- were similar. However, in the absence of HCO3-, mucus release stimulated by either PGE2 or 5-hydroxytryptamine (5-HT) was approximately half that stimulated by these molecules in the presence of HCO3-. Inhibition of HCO3- and fluid transport markedly reduced stimulated mucus release. However, neither absence of HCO3- nor inhibition of HCO3- transport affected fluid secretion rates, indicating that the effect of HCO3- removal on mucus release was not due to decreased fluid secretion. In a mouse model of CF (mice homozygous for the most common human CFTR mutation), intestinal mucus release was minimal when stimulated with either PGE2 or 5-HT in the presence or absence of HCO3-. These data suggest that normal mucus release requires concurrent HCO3- secretion and that the characteristically aggregated mucus observed in mucin-secreting organs in individuals with CF may be a consequence of defective HCO3- transport.

Quantitative Separation of the Bicarbonate from the Counter-cation Effect in Bean Plants

The effect of Rb+ and Na+ as counter-cations of HCO3 − was evaluated on bean (Phaseolus vulgaris L. cv. Poncho) plants using mixture experiment statistical methodology in a series of experiments set up in a controlled environment chamber. Mixture experiments using three components (Rb+, K+, and Na+) or two components (K+ and Na+) were conducted to delineate the toxicity of HCO3 − versus the counter-cation effect. The quantitative separation of the toxic effects was possible only when the individual stress had an additive effect when combined with the other stress. Potassium mixtures were used as reference for comparison with other mixtures because plants did not respond to K+, probably because it was included at a minimum concentration of 2.5 mm K+ or because it was supplied in the preestablishing solution. Rubidium caused a decrease in shoot dry weight (SDW), but SDW accumulation was even lower when HCO3 − was added to the Rb+ solutions. However, Rb+ was not included in follow-up experiments because the response of plants to Rb+ was very similar to that of Na+. The toxic effect of Na+ caused SDW to decrease at a rate of 3.7% per millimolar increase of Na+. However, the effect of HCO3 − was dependent on its concentration, because at 2.5 mm HCO3 −, the decrease in SDW was 12.7% per millimolar HCO3 −, whereas at 3.75, 5, and 5.65 mm, the decrease was 11.0%, 7.8%, and 10.7% per millimolar HCO3 −, respectively. At 7.5 mm HCO3 −, the decrease in SDW was 4.2% to 8.2% per millimolar increase in HCO3 −, respectively. The decreasing HCO3 − rate may be explained by the nonadditive effect between HCO3 − and Na+ at high alkalinity levels.

The effect of HCO3‐ on fatigue, pHi and K+ efflux in rat skeletal muscles

The effect of HCO3‐ on fatigue, pHi and K+ efflux in rat skeletal muscles

Ozonation of Spent Reactive Dye-Baths: Effect of HCO3-/CO32- Alkalinity

The effect of carbonate and bicarbonate alkalinity (soda ash buffer as 5,180 mg/L HCO3- alkalinity at pH 7 and as 5,100 mg/L CO32- alkalinity at pH 12) on the ozonation of reactive vinylsulphone dyestuffs in a simulated spent dye-bath has been studied at varying pHs. Adsorbable organic halogen (AOX) formation due to the high chloride content of the effluent and detoxification, which was evaluated in terms of the relative toxicity index Itox determined from the ED50 values for the marine photobacteria Vibrio fischeri, were also evaluated. Highest total organic carbon (56%), chemical oxygen demand (44%), and UV254 (77%) removals were achieved at pH 7 in the presence of HCO3- alkalinity. The fastest decolorization was observed for the case pH 2, the first order decolorization rate constant found as k620=0.16min-1, closely followed by the pH 12 case with soda ash (k620=0.12min-1) case. No positive correlation was evident between AOX, whose maximum value (=1.3 mg/L) appeared after 40 min ozonation at pH 7 and decreased to 0.54 mg/L after 120 min treatment, and Itox, which decreased to 0.16 at t=50min and increased rapidly thereafter. The Itox values were more related to color abatement kinetics. The maximum relative toxicity index of Itox=0.83 occurred after 120 min. It was also established that the presence of alkalinity in the spent reactive dye-bath had no negative impact on the oxidation rates. In contrast, its absence seriously inhibited treatment efficiency. It is speculated that, with added soda ash, the carbonate radicals HCO3⋅ and CO3⋅-, which are more stable and selective than OH⋅, were produced and promoted the oxidation process.