Chemical Bulletin of Kazakh National University

Using expired drotaverine for corrosion protection of steel in HCl solution

Liudmila E. Tsygankova — 2025-06-29

In the last two decades, the scientific literature has widely covered the use of expired medicinal preparations for anticorrosion protection of metals. The aim of this work is to study expired Drotaverine (No-shpa) as a corrosion inhibitor for St3 carbon steel in a 1 M HCl solution. Drotaverine concentrations ranged from 20-80 mg/L.
Studies were conducted using gravimetry, potentiodynamic polarization, impedance spectroscopy, and scanning electron microscopy. Gravimetric studies of Drotaverine’s inhibitory effect were carried out at room temperature for 2 and 24 hours, and at 80°C for 0.5 hours, showing a protective effect (Z, %) of 72, 82, and 96%, respectively, at a concentration of 80 mg/L. The Z values calculated from polarization and impedance measurements were close to those determined gravimetrically. The surface coverage of the electrode by the inhibitor was estimated, and it was shown that Drotaverine adsorption conforms to the Langmuir isotherm. The calculated free energy of adsorption, equal to -29 kJ/mol, indicates physical adsorption of the drug on the steel surface with some contribution from chemisorption. Drotaverine causes a deceleration of both cathodic and anodic electrode reactions.

New method for the synthesis of oxonium derivatives of closo-borate anions [BnHn]2-

Elena S. Boyarinova — 2025-06-29

This work investigates the reaction of tetrabutylammonium salts of [B10H10]2- and [B12H12]2- anions with tetrahydrofuran, 1,4-dioxane, and tetrahydropyran in the presence of aqueous H[BF4] and H2[SiF6] solutions. It is shown that these reactions yield mono-substituted derivatives of the closo-decaborate anion ([2-B10H9O(CH2)4]-, [2-B10H9O(CH2)4О]-, [2-B10H9O(CH2)5]-) and closo-dodecaborate anion ([B12H11O(CH2)4]-, [B12H11O(CH2)4О]-, [B12H11O(CH2)5]-) in high yields. It was proven that in the case of the [B10H10]2- anion, the reaction proceeds regioselectively, leading specifically to products with substituents in the equatorial belt of the boron cluster. The closo-dodecaborate anion derivative with an exo-polyhedral tetrahydropyran substituent was further functionalized by reaction with potassium cyanide in DMF. Studies showed that this reaction results in the opening of the cyclic substituent, forming a derivative containing a pendant cyano group attached to the boron cluster via a pentamethylene spacer. This compound can be further modified at the terminal group to obtain biologically active boron-containing derivatives, promising for use in ¹⁰B-neutron capture therapy (BNCT) of malignant tumors, as well as antimicrobial and antiviral therapy.
The structures of all obtained derivatives were confirmed using a comprehensive set of modern physical and physicochemical analytical methods (elemental analysis, IR spectroscopy, multinuclear NMR spectroscopy, ESI mass spectrometry).

Production Technology and Physicochemical Characteristics of Activated Carbon Derived from Industrial Waste

Sergei V. Nechipurenko — 2025-06-29

This study examines the specific features of the production technology of granular activated carbon obtained from substandard fine-grained carbon fractions, which are by-products of the special coke industrial production at JSC «Shubarkol Komir.» A technological scheme was developed for producing activated carbon based on this industrial waste, including the methods and conditions for granulation, carbonization, and activation. The physicochemical properties and structural characteristics of the resulting target carbon materials were evaluated.
Granular and powdered activated carbons were produced from coke fines with the following composition: 60% coke fines, 35% binder, and 5% chemical activating agent. The temperature dependencies of the activation process were determined. Using adsorption-structural analysis methods, the structure of the activated carbon was studied, revealing a well-developed porous structure that includes mesopores with slit sizes ranging from 2 to 32 nm.

Artificial protective coatings for lithium metal anode to improve its stability

Maksim S. Lepikhin — 2025-06-29

The use of lithium metal as an anode in lithium-metal batteries is desired due to its high capacity and highly negative potential but is still not achieved due to the high activity and consequent chemical and electrochemical instability of this metal. On contact with the electrolyte, a film (SEI) is formed on the lithium surface consisting of the electrolyte decomposition products. Typically, this film has a heterogeneous structure, making it unstable and it cracks during cycling, which leads to lithium local deposition in the form of outgrowths – dendrites. A short circuit can occur when the dendrites grow to the cathode, followed by a possible battery fire. To solve this problem, it was proposed to coat lithium anodes with artificial SEI with the desired properties: homogeneous structure, high ionic and low electronic conductivity, and mechanical and chemical stability. The main methods for applying such coatings are dipping, dripping, doctor blade smearing, chemical or electrochemical reaction with lithium, and techniques such as magnetron sputtering, atomic and molecular layer deposition, and plasma activation. In this review examples of artificial protective coatings of different nature on lithium, their structure and functional features are considered. The reasons for their enhancement of lithium-metal anode operation stability and the characteristics obtained as a result of anode protection by these films are also indicated. At comparison of various approaches to creation of artificial SEI the methodological problem on an estimation of their efficiency is revealed and the decision variant is offered.