Corrigendum to “Construction of hierarchical ZSM-5 zeolites by chelating-alkaline medium” [Materials Today Sustainability 13 (2021) 100070]

The binding of calcium and lead ions to carboxy derivatives of starch prepared by allowing nitrogen dioxide to act on native maize starch (procedure A) and on starch 2,3-dialdehyde derivatives of degrees of oxidation DO(d.a.) ≥ 0.94 (procedure B) was studied. The carboxy group content of the samples in the H+ form was 4.6 - 12.1 mmol g-1. The effect of alkaline medium on the stability of the carboxy derivatives and on their ability to bind and exchange cations was examined. The Ca2+ → 2K+ exchange was evaluated in terms of the decrease in the electrostatic free enthalpy Δ(Gel/N)KCa, determined by alkalimetric potentiometric titrations, and the binding of Pb2+ ions was evaluated in terms of the activity of the Pb2+ counter-ions determined in suspensions of Pb salts of the carboxy derivatives by means of an ion specific electrode. The IR and CD spectra revealed that the carboxystarch preparations obtained by procedure A contained, in addition to free carboxy groups, a considerable amount of carbonyl groups. During the conversion of the latter groups to the former, even in a weakly alkaline medium, the carboxy derivatives undergo an appreciable degradation and lose, to a great extent, their ability to bind and exchange cations. Procedure B, on the other hand, leads to highly selective starch and amylose carboxy derivatives, exhibiting a small amount of carbonyl groups and featuring a relative stability towards alkaline medium; their binding capacity is as high as 12 milliequivalents of cations per g of sample.

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Oxidation of polysubstituted pyridinium salts

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19821494 ◽

1982 ◽

Vol 47 (5) ◽

pp. 1494-1502 ◽

Cited By ~ 10

Author(s):

Petr Nesvadba ◽

Josef Kuthan

Keyword(s):

Alkaline Medium ◽

Electrophilic Substitution ◽

Pyridine Ring ◽

Potassium Ferricyanide ◽

Pyridinium Salts ◽

Complex Reaction

Oxidation of 1-substituted 2,4,6-triphenylpyridinium salts Ia-Ij with potassium ferricyanide in an alkaline medium was accompanied by contraction of the pyridine ring and formation of 1,2,3,5-tetrasubstituted pyrroles II. The derivative IIf underwent facile electrophilic substitution in the position 4. Contrary to compounds Ia-Ij, the 1-substituted-2,6-diphenylpyridinium salts IIIa,b were oxidized to give a complex reaction mixture containing 4-pyridones IVa,b.

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Outer-sphere interaction of (S)-asparagine and (S)-glutamine with [Co(NH3)6]3+ ion and its possible role in ligand substitution

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19872457 ◽

1987 ◽

Vol 52 (10) ◽

pp. 2457-2459

Author(s):

František Jursík

Keyword(s):

Amino Acids ◽

Transition Region ◽

Alkaline Medium ◽

Optical Activity ◽

Substitution Reaction ◽

Outer Sphere ◽

Ligand Substitution ◽

Cotton Effect ◽

Negative Cotton Effect

Optical activity of the achiral cation [Co(NH3)6]3+ is induced both by (S)-AsnONa and (S)-GlnONa, as shown by a negative Cotton effect in the 1A1g → 1T1g transition region. An outer-sphere interaction by three-point attachment of the amides can explain the fact that substitution reaction of [Co(NH3)6]3+ with the mentioned amides in an alkaline medium is unusually slow as compared with other amino acids.

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Adsorption and Oxidation of Thiosulfate on the Platinum Electrode in a Slightly Alkaline Medium

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20000001 ◽

2000 ◽

Vol 65 (1) ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Tomáš Loučka

Keyword(s):

Alkaline Medium ◽

Oxidation Reaction ◽

Open Circuit Potential ◽

Platinum Electrode ◽

Adsorbed Layer ◽

Open Circuit ◽

Adsorbed Hydrogen ◽

Oxidation Number ◽

Hydrogen Electrode ◽

Layer Region

The aim of this research was to study the oxidation and reduction of the adsorbed thiosulfate on the platinum electrode in a slightly alkaline medium. The adsorption was performed at the open circuit conditions. The reduction of the adsorbed layer in the hydrogen region is slower in a slightly alkaline medium than in acid. The mechanism of reduction and oxidation of adsorbed molecules is probably the same. The nonstationary currents measured in presence of thiosulfates showed that the change in the oxidation number does not take place during the adsorption in the double layer region. In the hydrogen region, thiosulfate replaces the adsorbed hydrogen while beeing reduced. Nonstationary currents at higher concentrations of thiosulfate indicate the presence of more layers on the electrode. Upon reaching higher concentrations of thiosulfate the oxidation reaction takes place between thiosulfate in solution and adsorbed product of its reduction. The open circuit potential of the platinum electrode measured in a thiosulfate solution was 0.780 and 0.783 V against the hydrogen electrode in the same solution.

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2D metal azolate framework as nanozyme for amperometric detection of glucose at physiological pH and alkaline medium

Microchimica Acta ◽

10.1007/s00604-021-04737-w ◽

2021 ◽

Vol 188 (3) ◽

Author(s):

Muhammad Adeel ◽

Vincenzo Canzonieri ◽

Salvatore Daniele ◽

Alberto Vomiero ◽

Flavio Rizzolio ◽

...

Keyword(s):

Alkaline Medium ◽

Amperometric Detection

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Cobalt Nanoparticle-Embedded Nitrogen-Doped Carbon Catalyst Derived from a Solid-State Metal-Organic Framework Complex for OER and HER Electrocatalysis

Energies ◽

10.3390/en14051320 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1320

Author(s):

Shaik Gouse Peera ◽

Ravindranadh Koutavarapu ◽

Chao Liu ◽

Gaddam Rajeshkhanna ◽

Arunchander Asokan ◽

...

Keyword(s):

Solid State ◽

Alkaline Medium ◽

Glassy Carbon ◽

Metal Organic Framework ◽

Electronic Conductivity ◽

Organic Ligand ◽

Synthesis Process ◽

Ni Foam ◽

Shell Nanoparticles ◽

Energy Devices

Electrochemical water splitting is considered a promising way of producing hydrogen and oxygen for various electrochemical energy devices. An efficient single, bi-functional electrocatalyst that can perform hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs) is highly essential. In this work, Co@NC core-shell nanoparticles were synthesized via a simple, eco-friendly, solid-state synthesis process, using cobalt nitrate and with pyrazole as the N and C source. The morphological analysis of the resulting Co@NC nanoparticles was performed with a scanning and transmission electron microscope, which showed Co nanoparticles as the core and the pyrolysis of pyrazole organic ligand N-doped carbon derived shell structure. The unique Co@NC nanostructures had excellent redox sites for electrocatalysis, wherein the N-doped carbon shell exhibited superior electronic conductivity in the Co@NC catalyst. The resulting Co@NC nanocatalyst showed considerable HER and OER activity in an alkaline medium. The Co@NC catalyst exhibited HERs overpotentials of 243 and 170 mV at 10 mA∙cm−2 on glassy carbon and Ni foam electrodes, respectively, whereas OERs were exhibited overpotentials of 450 and 452 mV at a current density of 10 and 50 mA∙cm−2 on glassy carbon electrode and Ni foam, respectively. Moreover, the Co@NC catalyst also showed admirable durability for OERs in an alkaline medium.

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