Potassium Bicarbonate Solution Research Articles

Modifying Copper Local Environment with Electrolyte Additives to Alter CO2 Electroreduction vs Hydrogen Evolution

CO2 electroreduction (CO2ER) by using renewable energy resources is a promising method to mitigate the CO2 level in the atmosphere as well as produce valuable chemicals. Local environment at the electrode–electrolyte interface plays a key role in CO2ER activity and selectivity along with its competing hydrogen evolution reaction (HER). In addition to the catalyst and reactor design, electrolyte also has a significant impact on the interface. Herein, electrolyte additives were used to modify the local environment around the Cu catalyst during CO2ER. For this purpose, 10 mM ionic additives with bis(trifluoromethylsulfonyl)imide ([NTF2]−) and dicyanamide ([DCA]−) as anions and 1-butyl-3-methylimidazolium ([BMIM]+), potassium (K+), or sodium (Na+) as cations have been added to an aqueous potassium bicarbonate solution (0.1 M KHCO3). COMSOL Multiphysics was also used to calculate the local pH and CO2 concentration at the electrode–electrolyte interface in different electrolytes. Results showed that the local environment modifications by the electrolyte additives altered the activity and selectivity of Cu in CO2ER. It was found that the CO2ER activity at −0.92 V was enhanced when using anions with high CO2 affinity and high hydrophobicity, such as [NTF2]−. Among [NTF2]−-based additives, [BMIM][NTF2] had a higher faradaic efficiency (FE) for formate (38.7%) compared to K[NTF2] (23.2%) and Na[NTF2] (18.5%) at −0.92 V likely due to the presence of imidazolium cations that can further stabilize the intermediates on the surface and enhance CO2ER. Electrolytes containing [DCA]−-based additives with high hydrophilicity and low CO2 affinity had a very high HER selectivity (>90% FEH2) and low CO2ER selectivity regardless of the cation nature. This observation is attributed to the presence of hydrophilic [BMIM][DCA] in the vicinity of the catalyst, which impacts the microenvironment around the catalyst. We observed that [DCA]− anions have a high affinity to adsorb on Cu catalysts as soon as the catalyst is submerged in the electrolyte. Although FTIR showed that [DCA]− anions desorb from the surface at negative potentials, it is likely that [DCA]− anions still remain in the proximity of the electrode, next to the adsorbed cations, impacting the transport of H2O and CO2, and altering the product selectivity. COMSOL calculations showed that the local pH is directly proportional to the H2 evolution activity. Also, hydrophilic salts such as those with the [DCA]− anion had a more alkaline local pH, which led to a lower CO2 concentration in the vicinity of the catalyst.

Imaging electrochemically synthesized Cu2O cubes and their morphological evolution under conditions relevant to CO2 electroreduction

Copper is a widely studied catalyst material for the electrochemical conversion of carbon dioxide to valuable hydrocarbons. In particular, copper-based nanostructures expressing predominantly {100} facets have shown high selectivity toward ethylene formation, a desired reaction product. However, the stability of such tailored nanostructures under reaction conditions remains poorly understood. Here, using liquid cell transmission electron microscopy, we show the formation of cubic copper oxide particles from copper sulfate solutions during direct electrochemical synthesis and their subsequent morphological evolution in a carbon dioxide-saturated 0.1 M potassium bicarbonate solution under a reductive potential. Shape-selected synthesis of copper oxide cubes was achieved through: (1) the addition of chloride ions and (2) alternating the potentials within a narrow window where the deposited non-cubic particles dissolve, but cubic ones do not. Our results indicate that copper oxide cubes change their morphology rapidly under carbon dioxide electroreduction-relevant conditions, leading to an extensive re-structuring of the working electrode surface.

Evaluation of Inhibitory Effect of Some Bicarbonate Salts and Fungicides Against Hazelnut Powdery Mildew

Hazelnut (Corylus avellana L.) which is intensively grown in the Black Sea region is the most important agricultural product of Turkey. Hazelnut production and quality are negatively affected by several diseases and pests. Powdery mildew is nowadays one of the most common diseases in almost whole hazelnut producing areas. The disease is caused by two different species, Phyllactinia guttata (Wallr. et Lev.) Fr. and Erysiphe corylacearum U. Braun & S. Takam. For the last 4 years, E. corylacearum, a newly invasive fungus in Turkey, has been caused significant economic losses. In the present study, the efficacy of ammonium, potassium and sodium bicarbonates, and two fungicides were evaluated in field trials against powdery mildew on hazelnuts in Samsun in 2016. The application rates of compounds used in the experiment were as follows: ammonium, potassium and sodium bicarbonates (Sigma-Aldrich, Seelze, Germany) at 1.5, 3, 4.5 and 6% (w/v); Collis® SC (100 g/l Kresoxim methyl +200 g/l Boscalid, BASF, Spain) at 30 ml/100 l and Sulflow® 80 WG (Sulphur 800 g/l, Agrofarm, Turkey) at 400 g/100 l. Of the compounds tested, except for fungicides, sodium was found to be the most effective in controlling the powdery mildew on hazelnuts, followed by potassium and ammonium, respectively. Among those three, ammonium bicarbonate was ineffective against fruit infections of the disease. There was also no significant difference between inhibitory effects of 6% sodium bicarbonate, Collis and Sulflow against the disease (P < 0.05). In addition, bicarbonate salts was phytotoxic to hazelnut leaves at concentrations greater than 1.5%. The results indicate that sodium or potassium bicarbonate solutions seems to be a useful biocompatible fungicide for controlling the powdery mildew on hazelnuts.

Recycling of Electric Vehicle Lithium Ion Batteries: Development of a Novel Method to Recover Lithium from Leached Cathodes Based on Donnan Dialysis

Lithium ion batteries (LIBs) are the battery of choice for electric vehicles (EVs) at present and for the foreseeable future. Adoption of EVs at a rate as high as possible is highly desirable since EVs have no direct emissions of green-house gases, smog causing chemicals, or particulate matter. The IEA has developed a roadmap to achieve 50% electrification of passenger vehicles by 2050. Unfortunately the literature shows that by the mid 2020’s lithium producers will not be able to keep up with the demand forecasted by the roadmap without recycling of EV LIBs [1]. To avoid a bottleneck, we calculated that depleated EV LIBs should be recycled and the lithium contained therein be used to make new LIBs at a rate of 28% and 75% in 2025 and 2040 (if the batteries last 5 years) or 40% and 96% in 2025 and 2035 respectively (if the batteries last 10 years). Currently, LIB cathodes are recycled by leaching the cathodes in acid, recovering transition metals one at a time by solvent extraction, and recovering lithium as lithium carbonate by precipitation with sodium carbonate. Leaching efficiencies of ~100% have been reported, but precipitation efficiencies for lithium have stagnated at 80% for the last 17 years [2], [3]. Additionally the highest purity lithium carbonate purity reported is 99.18% [3]. The purity required for EV LIBs is 99.9 to 99.99%. We are developing a novel process to recover lithium from leachate (see the figure below) based on Donnan dialysis with cation exchange membranes (CEM). Lithium ions are extracted first with a monovalent CEM ({1} in the figure) then ions of the other cathode metals (Co, Mn, and Ni) with a polyvalent CEM ({2} in the figure). Lithium is recovered by: neutralizing the acidic Li solution obtained from the first monovalent CEM ({1} in the figure); exchanging Li ions with K ions from a potassium bicarbonate solution pressurized with CO2 with another monovalent CEM ({3} in the figure); depressurizing the Li enriched KHCO3 solution, which results in the precipitation of lithium carbonate (the desired product); adding KHCO3 to make up the K ions exchanged; re-pressurising; and recycling the entire solution past the monovalent cation exchange membrane ({3} in the figure). The transition metal salts recovered in step {2} may be separated by solvent extraction or crystalized and used mixed in making new cathodes with the same chemistry as the leached cathodes. The work we have performed so far is equilibrium calculations on each of the stages and preliminary experiments to determine the mass transfer coefficients across the membranes. For steps {1} and {2} we assumed three counter-current equilibrium stages and stripping acid [H+] =0.90 M. We assumed a leach solution concentration of [Li+] = 0.285 M, [Co++] = [Ni++] = [Mn++] = 0.095 M for step {1} and [Co++] = [Ni++] = [Mn++] = 0.095 M for step {2}. We obtained a theoretical lithium recovery of 97.6% in step {1}, and a Co, Ni, and Mn theoretical recoveries of 99.1% in step {2}. For step {3} we assumed an incoming [Li+] = 0.278 M, a stripping solution of [KHCO3] =2 M and [Li+] =0.0935 M (this is the solubility limit of LiHCO3 prior to re-pressurization with CO2). The theoretical lithium recovery using three counter-current equilibrium stages was calculated to be 95.3%. Thus the theoretical overall maximum lithium recovery rate given by the process is 93.0%, which is superior to values presented in literature and is achievable in a process free of sodium, where leaching solution is recyclable, and where there is no heating. Our preliminary experiments reveal that using a Neosepta CMS monovalent cation exchange membrane the transmembrane mass transfer coefficients of Mn++, Co++, Ni++, when these ions are present at concentrations between 0.005 and 0.095 M and when the stripping acid [H+] is between 0.10 and 0.90 M, are less than 1% of the coefficient of lithium. Thus, the Neosepta CMS monovalent CEM provides an excellent separation of lithium from cobalt, nickel, and manganese. [1] H. Vikström, S. Davidsson, and M. Höök, “Lithium availability and future production outlooks,” Appl. Energy, vol. 110, pp. 252–266, Oct. 2013. [2] P. Zhang, T. Yokoyama, O. Itabashi, Y. Wakui, T. M. Suzuki, and K. Inoue, “Hydrometallurgical process for recovery of metal values from spent lithium-ion secondary batteries,” Hydrometallurgy, vol. 47, no. 2–3, pp. 259–271, 1998. [3] X. Chen, Y. Chen, T. Zhou, D. Liu, H. Hu, and S. Fan, “Hydrometallurgical recovery of metal values from sulfuric acid leaching liquor of spent lithium-ion batteries,” Waste Manag., vol. 38, pp. 349–356, 2015. Figure 1

Enzymatic Process for N-Substituted (3S)- and (3R)-3-Hydroxypyrrolidin-2-ones

Lipase PS 30 (immobilized on polypropylene) from Pseudomonas cepacia was used for enantioselective esterification of (RS)-1-(2-fluoro-4-iodophenyl)-3-hydroxypyrrolidin-2-one by using succinic anhydride and 2-methyltetrahydrofuran at 4 °C. The isolation of desired alcohol avoided use of column chromatography, a simple solvent extraction of undesired (R)-4-((1-(2-fluoro-4-iodophenyl)-2-oxopyrrolidin-3-yl)oxy)-4-oxobutanoic acid into 5% potassium bicarbonate solution separated pure desired (S)-1-(2-fluoro-4-iodophenyl)-3-hydroxypyrrolidin-2-one into the 2-methyltetrahydrofuran solution. The reaction conditions were optimized, and (S)-1-(2-fluoro-4-iodophenyl)-3-hydroxypyrrolidin-2-one was prepared in high enantiomeric excess >99% and yield ∼40% (theoretically possible yield 50%). Novozym 435 (Candida antarctica lipase B) was found to be a suitable biocatalyst for the resolution of (RS)-1-(6-bromo-2-methylpyridin-3-yl)-2-oxopyrrolidin-3-yl acetate to form the undesired S-acetate and the desired R-alcohol. The...

A flow injection analyser conductometric coupled system for the field analysis of free dissolved CO2 and total dissolved inorganic carbon in natural waters

A flow injection analyser coupled with a gas diffusion membrane and a conductometric microdetector was adapted for the field analysis of natural concentrations of free dissolved CO2 and dissolved inorganic carbon in natural waters and used in a number of field campaigns for marine water monitoring. The dissolved gaseous CO2 presents naturally, or that generated by acidification of the sample, is separated by diffusion using a hydrophobic semipermeable gas porous membrane, and the permeating gas is incorporated into a stream of deionised water and measured by means of an electrical conductometric microdetector. In order to make the system suitable and easy to use for in-field measurements aboard oceanographic ships, the single components of the analyser were compacted into a robust and easy to use system. The calibration of the system is carried out by using standard solutions of potassium bicarbonate at two concentration ranges. Calibration and sample measurements are carried out inside a temperature-constant chamber at 25 °C and in an inert atmosphere (N2). The detection and quantification limits of the method, evaluated as 3 and 10 times the standard deviation of a series of measurements of the matrix solution were 2.9 and 9.6 μmol/kg of CO2, respectively. Data quality for dissolved inorganic carbon was checked with replicate measurements of a certified reference material (A. Dickson, Scripps Institution of Oceanography, University of California, San Diego), both accuracy and repeatability were -3.3% and 10%, respectively. Optimization, performance qualification of the system and its application in various natural water samples are reported and discussed. In the future, the calibration step will be operated automatically in order to improve the analytical performance and the applicability will be increased in the course of experimental surveys carried out both in marine and freshwater ecosystems. Considering the present stage of development of the method, it can only be applied for studying of the carbon cycle in oxic environments.

Contribution of Transmembrane Tumor Necrosis Factor to Host Defense against Mycobacterium bovis Bacillus Calmette-Guerin and Mycobacterium tuberculosis Infections

To study the specific role of transmembrane tumor necrosis factor (TmTNF) in host defense mechanisms against bacillus Calmette-Guerin (BCG) and Mycobacterium tuberculosis infections, we compared the immune responses of TNF/lymphotoxin (LT)-alpha(-/-) mice expressing a noncleavable transgenic TmTNF (TmTNF tg) to those of TNF/LT-alpha(-/-) and wild-type mice. Susceptibility of TNF/LT-alpha(-/-) mice to BCG infection was associated with impaired induction of systemic RANTES but not of monocyte chemoattractant protein 1 (MCP-1), the development of excessive local and systemic Th1-type immune responses, and a substantially reduced inducible nitric oxide synthase (iNOS) activity. Resistance of TmTNF tg mice to BCG infection was associated with efficient activation of iNOS in granulomas and with the regulated release of local and systemic chemokines and Th1-type cytokines. However, M. tuberculosis infection of TmTNF tg mice resulted in longer survival and enhanced resistance compared to TNF/LT-alpha(-/-) mice but higher sensitivity than wild-type mice. TmTNF tg mice exhibited reduced pulmonary iNOS expression and showed an exacerbated cellular infiltration in the lungs despite a modest bacillary content. Our data thus indicate a role for TmTNF in host defense against mycobacteria by contributing to induction and regulation of Th1-type cytokine and chemokine expression leading to development of bactericidal granulomas expressing iNOS, which critically determines susceptibility versus resistance of the host to mycobacterial infections.

Thermodynamics of proton dissociation from aqueous bicarbonate: apparent molar volumes and apparent molar heat capacities of potassium carbonate and potassium bicarbonate at T=(278.15 to 393.15) K and at the pressure 0.35 MPa

We have determined the apparent molar volumes V φ and apparent molar heat capacities C p, φ of aqueous potassium carbonate and potassium bicarbonate solutions in the ranges (0.014⩽ m/(mol · kg −1)⩽0.51) and (278.15⩽ T/K⩽393.15) at the pressure p=0.35 MPa. Corrections for speciation due to hydrolysis and disproportionation in solution were applied using Young's rule, and semi-empirical equations representing ( V φ , m, T) and ( C p, φ , m, T) for the species {2K +, CO 3 2−(aq)} and {K +, HCO 3 −(aq)} were fitted to the experimental results. We have used these equations to estimate the change in volume Δ r V m, change in heat capacity Δ r C p,m, enthalpy change Δ r H m, entropy change Δ r S m, and equilibrium molality quotient pQ for the second proton dissociation reaction from aqueous carbonic acid.

Photoelectrocatalytic production of hydrogen from natural seawater under sunlight

It is shown, for the first time, that hydrogen can be produced photoelectrocatalytically from natural seawater under sunlight at ambient temperature without the assistance of externally applied bias potential by the use of a materially optimized thin film transparent titania photocatalyst. A SUPEC (single unit photoelectrocatalysis) cell, combining the thin film photocatalyst and an electrocatalyst into one sheet, is constructed to produce hydrogen at a rate of 0.4 liter h −1 given a 1 m 2 cross-sectional area of sunlight irradiation on the photocatalyst. The photocatalyst remains stable and active in natural seawater. Also, quantum efficiency for photon-to-current conversion, measured in natural seawater under a constant photon irradiation and without bias potential, reached 54% as the wavelength was varied systematically. Both the hydrogen production rate and the quantum efficiency are at the same level as in the case with a typical electrolyte such as potassium bicarbonate solution. Seawater is a natural electrolyte solution which can be used without modification for photocatalytic water decomposition.

Bicarbonate solutions control powdery mildew (Leveillula taurica) on sweet red pepper and reduce the development of postharvest fruit rotting

Disease severity of powdery mildew (causal agentLeveillula taurica (Lev.) Arn.) on pepper (Capsicum annuum), defoliation and fruit sunscald rating were significantly reduced (P=0.05) by foliar applications of sodium or potassium bicarbonate solutions, compared with water or penconazole (Ophir). Preharvest application of bicarbonate solutions significantly reduced (P=0.05) postharvest decay development on sweet red pepper fruits.

An Improved Solid Phase Extraction Procedure for the Determination of Antidepressants in Serum by Column Liquid Chromatography

Abstract A convenient and economical procedure for the isolation of antidepressant drugs from serum is described. A 0.7 mL aliquot of the sample after the addition of trimipramine or protriptyline as the internal standard is vortex mixed with 0.7 mL of acetonitrile and centrifuged. The supernatant is applied to 1-mL BondElut C-18 silica extraction column which has been conditioned by subsequent washing with 1 M HCI, methanol, water, and 1% potassium bicarbonate solution. After passing the sample at a slow rate, the column is washed twice with water and once with acetonitrile. The desired compounds are then eluted with a 0.25 mL aliquot of a mixture of 35% perchloric acid and methanol (1:20). A 50-μ L aliquot of the eluate is injected onto a 15 cm × 4.6 mm (i.d.) column packed with 5-μ m C-8 silica particles, which is eluted at ambient temperature with a mobile phase containing tetramethylammoniun perchlorate and acetonitrile. The peaks are detected with an absorbance detector at 215 nm or 226 nm for fluox...

SCREENING FOR ALKALINITY TOLERANCE IN PRUNUS WITH A HIGH CARBONATE SOLUTION

Peach trees when grown in calcareous soils frequently exhibit lime-induced iron chlorosis. There have been numerous reports of rootstock tolerant to soil alkalinity but given the wide range of field conditions under which the comparison were made, it is difficult to quantify the relative tolerance of the different rootstock. A greenhouse screening procedure using a 0.5g/liter potassium bicarbonate solution (pH 8.0-8.3) was employed to compare the tolerance levels of 50 peach, almond and hybrid lines. Most peach lines tested were very susceptible (Nemaguard) to susceptible (Nemared, Lovell). A few exhibited a low level of tolerance (Montclar, Rutger Red Leaf, Rancho Resistant). High levels of tolerance were found with in almond and almond-peach hybrid families.

Measurement of binary and ternary mutual diffusion coefficients of aqueous sodium and potassium bicarbonate solutions at 25.degree.C

Measurement of binary and ternary mutual diffusion coefficients of aqueous sodium and potassium bicarbonate solutions at 25.degree.C

Purification and characterization of commercial NADH and accompanying dehydrogenase inhibitors

The anion-exchange chromatography of commercial NADH using a potassium bicarbonate solution as eluent yields highly pure NADH with good stability. Twelve compounds are also separated which act as dehydrogenase inhibitors. The main impurities are further characterized. The compound mainly responsible for residual optical density in commercial NADH preparations is probably a stereoisomer of NADH which is in reversible equilibrium with NADH at pH values in the range 5–7. A method of thin-layer chromatography, to check commercial NADH preparations for impurities, is described.

Azole Series. III. Reactions of 2-Acylamino-2-cyanoacetamides leading to 5-Aminooxazole-4-carboxamides and to Oxazolo [5, 4-d] pyrimidines

Reaction for preparation of a new series of 5-acylaminooxazole-4-carboxamides has been found. 5-Acetamidooxazole-4-carboxamides were obtained by heating 2-acylamino-2-cyanoacetamides with acetic anhydride in the presence of perchloric acid. Analogous 5-form-amido derivatives were also obtained by heating the same substrates with a mixture of formic acid and acetic anhydride in the presence of hydrochloric acid. Trials for synthesis of oxazolo [5, 4-d] pyrimidine-7-ol from the 5-acylaminooxazole-4-carboxamide obtained were also successful in some cases by means of heating with potassium bicarbonate solution.

The Dissolution and Anion Exchange Behavior of Rare Earth and Other Metallic Elements in Potassium Bicarbonate, Potassium Carbonate and Ammonium Carbonate Solutions

Abstract The amounts of rare earth ions dissolved in a potassium bicarbonate solution, as well as those of other metallic ions dissolved in potassium bicarbonate, potassium carbonate and ammonium carbonate solutions, have been measured. Moreover, the minimum concentrations of potassium bicarbonate, potassium carbonate and ammonium carbonate required to dissolve the precipitates of the metallic bicarbonate and carbonate completely has been determined, and the distribution coefficients, Kd, of the completely dissolved metallic ions between an anion exchange resin and a potassium bicarbonate, potassium carbonate or ammonium carbonate solution had been measured. On the basis of those findings, the dissolution and anion exchange behavior of the metallic ions has been discussed, and the applicability to an analytical separation has been described.

Studies on reduction waves of copper and lead ions in sodium bicarbonate supporting electrolyte using an A.C. Polarograph

According to the present study using a.c. polarography, copper and lead ions were found to exist as co-ordinated compounds such as [Cu(OH) 2(HCO 3) 2] 2− and [Pb(OH) 2 (HCO 3) 2] 2−, in solutions of potassium bicarbonate, the concentration of which ranged from 0.5–1 M, having a pH value 8.8–10.

The Reduction Waves of Copper and Lead Ions in Potassium Bicarbonate Solution

炭酸水素カリウムおよび水素イオン濃度の変化による頂点電位の移動から炭酸水素カリウム支持塩中の銅および鉛の溶存状態について推定した結果,炭酸水素カリウムの濃度が 0.5～1mol/l, pH 8.8～10 の範囲内では,銅および鉛は OH-と HCO8- とを配位して,銅は [Cu(OH)2(HCO3)2]2-,また鉛は [Pb(OH)2(HCO3)2]2-のような組成で溶存するものと思われる。