Journal of Chemical Technology and Metallurgy

SYNTHESIS AND CHARACTERISATION OF BIO-SOURCED COPOLYMERS CONTAINING MYRCENE AND CONJUGATED DIENE INITIATED BY NEODYMIUM-BASED COORDINATION CATALYSTS

Abdelaziz El Bouadili — 2025-09-03

Myrcene is a promising alternative to petroleum-based materials. This conjugated terpene, found in many essential oils, has the potential to be used as a source material for producing elastomers derived entirely from biosourced materials. It could serve as a substitute for polymers like polybutadiene and other types of petroleum-based polymers. At 70 °C in toluene, a copolymer poly(1,4-trans-myrcene-co-styrene) and polymyrcene-block-polyisoprene are created using neodymium trisborohydride Nd(BH₄)₃(THF)₃ in combination with n-butylethyl magnesium (C₂H₅MgC₄H₉). The use of this catalytic system for the statistical copolymerization of myrcene-styrene is a highly efficient method that leads to the production of a copolymer with excellent stereoregularity and a high yield. Nd(BH₄)₃(THF)₃/C₂H₅MgC₄H₉ is also effective in the production of block copolymers (myrcene-isoprene). These resulting copolymers consist of an isoprene content of approximately 41 % and show no significant change in polymyrcene stereoselectivity despite the presence of a significant amount of isoprene. Additionally, the incorporation of myrcene into the copolymers makes it possible to soften the trans-isoprene polymer. Therefore, this catalytic system provides a valuable and promising method for synthesizing copolymers that serve as interesting precursors for biosourced elastomers.

SYNTHESIS AND PHOTOSTABILITY OF SOME NEW 1,8-NAPHTHALIMIDE DERIVATIVES AS COLOUR MONOMERS FOR FLUORESCENT POLYMERS

Polya Miladinova — 2025-09-03

Two new polymerizable 1,8-naphthalimide fluorophores containing residue of an amino acid in the fourth position of the naphthalimide ring have been synthesized. Their copolymers with methyl methacrylate were obtained. The colour coordinates of the prepared polymer have been determined. The photostability of the dyes and copolymers in dimethylformamide have been investigated and an increase in the photostability of dyes included in polymer with about 25-30 % was observed. The photostability of the polymer films obtained with copolymers and polymethyl methacrylate dyed “in mass” with the synthesized dyes have been determined by a change of colour coordinates and reflectance during the radiation with UV light. As a result of this investigation, it can be concluded that the dyes have good photostability and can be applied both as fluorescent dyes for dyeing of polymer materials “in mass” and as colour fluorescent monomers for obtaining of fluorescent polymers.

INFLUENCE OF VARIOUS SOLVENTS ON THE POLYPHENOLIC COMPOSITION OF EXTRACTS FROM CANNABIS SATIVA L. AND CANNABIS INDICA PLANTS

Nikolay Kaloyanov — 2025-09-03

The extraction ability of different solvents and their mixtures with water is nvestigated towards the qualitative and quantitative polyphenolic composition extracted from the plants Cannabis Sativa L. and Cannabis Indica and it is determined by HPLC - DAD technique. Extraction is carried out by the maceration method, and the effect of following solvents is compared: 96 % ethanol, 80 % ethanol (aq.), 50 % ethanol (aq.), dichloromethane, acetone, 80 % acetone (aq.) and 50 % acetone (aq.). The results derived reveal that acetone/water mixture (1:1) can extract
the largest number of polyphenols from Cannabis Sativa L. - epigallocatechin, rutin, myricetin and kaempferol, as first three of them present in the largest amounts, compared to the other solvents. It is worth noting that ethanol/water mixtures (80:20 and 50:50) both extract three of the studied polyphenols from Cannabis Sativa L. Considering the polyphenolic content in Cannabis Indica extracts, it is found out only ethanol/water (1:1) extracts the largest number of polyphenols - epigallocatechin, rutin, myricetin and quercetin, as the amount of all these is the largest, compared to the other solvents. Another ethanol/water mixture (80:20) is also quite effective in extracting the traced compounds, since three polyphenols - rutin, myricetin and quercetin are identified.

TWO-ANTENNARY OLIGOGLYCINE COMPLEXES WITH INDOMETHACIN IN AQUEOUS MEDIA: FORMATION AND CHARACTERIZATION

Eduarda Encheva — 2025-09-03

Two-antennary oligoglycines are synthetic, biocompatible bola-amphiphiles composed of homologs with varying hydrophobic-to-hydrophilic ratios. These molecules exhibit a pronounced tendency for self-assembly in aqueous media, resulting in the formation of well-defined supramolecular structures known as tectomers. The present study is focused on one representative of the antennary olygoglycine and investigates its potential as a nanocarrier for hydrophobic drugs. The non-steroidal anti-inflammatory drug indomethacin is used as a model hydrophobic compound. To maximize the entrapment of the drug, we develop an experimental procedure, including the preliminary formation of tectomers at various pH values, followed by the addition of indomethacin. The obtained oligoglycine-indomethacin complexes are further characterized using UV-Vis spectroscopy, Dynamic Light Scattering, and Thin-Liquid-Film techniques. The results demonstrate that the two-antennary oligoglicine effectively captures indomethacin and forms stable complexes in aqueous media. We outline the optimal conditions for drug entrapment and propose hypotheses regarding the mechanisms behind the formation of the mixed complexes. This study advances the understanding of interactions between two-antennary oligoglycines and hydrophobic compounds and highlights their potential for biomedical applications.

SYNTHESIS AND PHYSICOCHEMICAL PROPERTIES OF NEW TRIPLE LUTETIUM TELLURITES

Aitolkyn Toibek — 2025-09-03

New ternary lutetium tellurites LuMeFeTeO₆ (Me – Sr, Ba) are synthesized using ceramic technology from oxides Lu₂O₃, TeO₂, Fe₂O₃, carbonates SrCO₃ and BaCO₃. Using X-ray phase analysis, we confirmed the individuality, and determined the types of syngony, unit cell parameters, X-ray and pycnometric densities of compounds. It has been confirmed that tellurites crystallize in the tetragonal system with a distorted perovskite structural type. Using dynamic calorimetry in the temperature range 298.15-673 K, we studied the isobaric heat capacities of tellurites and derived equations for the Cp(T) dependence.The standard heat capacity of new tellurites has been determined, establishing a fundamental constant. We have calculated temperature dependences of the thermodynamic functions S⁰(T), H⁰(T) – H⁰ (298.15), Фхх(Т). The study results are significant for inorganic and physical chemistry of oxide materials, as well as inorganic materials science. They can be utilized for inclusion in reference books and thermodynamic data banks.

PHASE COMPOSITION AND MICROMORPHOLOGY OF POLYPHASE DIOPSIDE-BEARING MATERIALS

Bojidar Jivov — 2025-09-03

Based on natural carbonate raw materials, oxide components and fluorite, polyphase materials with a silicate composition were synthesized in laboratory conditions. The phase composition, structure and micromorphology of the obtained experimental samples were studied. Their textural properties - medium to micro-grained, spinifex or chilled marginal zones, attest that they have crystalized from a melt. In separate areas, gradual transitions from one type of texture to another and a limited presence of amorphous zones were observed. The diopside is the main phase that appear in all samples as prismatic to needle-shaped crystals. Fluorite presents in small amount in all samples with spheroidal to irregular shape. Wollastonite, akermanite, calcite and quartz also present as important phases according to sample’s composition. Zincian hydroxide, chromite and an unidentified pigment are small constituents and reflect addition of various metals as colorants.

OPTIMIZATION APPROACHES FOR ENHANCED PRODUCTION OF PHYTASE FROM THE HALOPHILIC BACTERIUM COBETIA MARINA STRAIN 439

Ivanka Boyadzhieva — 2025-09-03

Phytase catalyzes the breakdown of complex organic forms of phosphorus into simpler forms by sequential hydrolysis of phosphate-ester bonds to release inorganic phosphate. Supplementation of feed with bacterial phytase can therefore improve the bioavailability of phosphorus and trace elements. In the present study, the production of phytase by a strain of Cobetia marina isolated from the lye of the Burgas salt pans and the optimization of culture conditions to enhance phytase production are reported. The effects of physical conditions and nutrients on phytase production were investigated. Physical parameters studied included fermentation time, inoculum size, agitation, pH and temperature. Maximum growth, as well as enzyme production (15.3 U mg^-1) were recorded after 72 h incubation period. To increase the level of enzyme production, different culture conditions were applied and the optimum temperature and pH for phytase production were found to be 35^oC and pH 7.5, respectively. Nutrient factors studied included carbon source, nitrogen source, substrate type and concentration, NaCl concentration and metal ions (salts). Our studies showed that the optimum phytase production was achieved using a mineral medium supplemented with: 1.5% maltose, 0.5% NaNO₃, 0.7% sodium phytate and 7% NaCl. Among the metal ions tested K⁺, Mn²⁺ and Fe²⁺ were found to have no effect on enzyme production. However, the removal of Ca²⁺ and Mg²⁺ from the production medium, lead to a decrease in strain growth and phytase production. Metal ions like Co²⁺, Zn²⁺, Ni²⁺, Hg²⁺, Ag²⁺ and the various detergents tested, caused a significant inhibition on phytase production.

As a result of the optimization approaches applied the production level of phytase was enhanced 2.7-fold and (40.5 U mg^-1) compared to the initial enzyme yield.

INFLUENCE OF THE SURFACTANT CONCENTRATION ON THE ROSE OIL FILLED UREA-FORMALDEHYDE MICROCAPSULES

Stanislav Bayryamov — 2025-09-03

The microencapsulation process proceeds much more efficiently, with a higher yield and quality of the resulting microcapsules in the presence of an emulsifier. Its influence is due, on the one hand, to the reduction in the diameter of the microcapsules and on the other hand - to an increase in the thickness, density and quality of the capsule wall. However, the type and amount of emulsifier must be precisely selected to obtain satisfactory results, while avoiding the adverse effect of capsule agglomeration and increasing the cost of the process. In the presented work, SDS was used in different concentrations: 0 %, 0.5 %, 1 %, 2 %, 3 %, 4 %, 5 % for encapsulation of rose oil by in situ polymerization between urea and formaldehyde. Experimental results showed that the efficiency of the microencapsulation process increased with raising surfactant concentration. Nevertheless, the presence of a large amount of surfactant (over 3 %) was undesirable, due to an increase in the viscosity of the reaction medium, followed by an increase in the size of the microcapsules because of their sticking together. In addition, the presence of a large amount of surfactant is economically unprofitable, which is the reason for realizing these studies with the aim of selecting the optimal amount of emulsifier.

GRAPHENE OXIDE-BASED HYDROGEL IN PHENOL SENSORS

Razan AL-Zghoul — 2025-09-03

This study aims to develop and evaluate a nanocomposite hydrogel film sensor for accurately detecting phenol in various real samples. A nanocomposite hydrogel film was synthesised using a three-dimensional network structure formed by poly (vinyl alcohol) (PVA) and gum Arabic (GA) as initiators, graphene oxide (GO) as functional
monomers, and citric acid (CA) as a cross-linker. The hydrogel’s morphological, structural, and elemental properties were characterised through microscopic and spectroscopic techniques. The hydrogel film-based sensor employed phenol as “imprinted molecules” and phosphate buffer as the solvent. The sensor demonstrated high sensitivity and specificity in detecting phenol within the concentration range of 1 to 50 μM, with a low detection limit of 0.01 mM. The interaction between phenol and the GO nanocomposite within the hydrogel film underpins the sensor’s performance. The findings highlight the potential of GO-based hydrogels as high-performance materials for sensing applications. This research advances environmental monitoring technologies, facilitating the accurate and specific recognition of toxic phenolic compounds like phenol in industrial and environmental settings.

EFFECT OF POST-WELD HEAT TREATMENT ON TENSILE PROPERTIES OF FRICTION STIR-WELDED JOINTS OF NANOSTRUCTURED AA2024 ALLOY

Majid Naseri — 2025-09-03

Herein, the effect of post-weld heat treatment on the tensile properties of friction stir-welded (FSW) joints of nano/ultrafine-grained (NG/UFG) AA2024 alloy sheets produced by accumulative roll bonding (ARB) was investigated. Continuous and discontinuous dynamic recrystallizations were the main mechanisms of microstructure evolution in the stir zone of joints. As a result of recrystallization and larger grain sizes achieved during FSW, the ARB followed by FSW improved ductility and strain hardening. The ARB specimens had yield strength, tensile strength, and elongation values of 265 MPa, 450 MPa, and 7 %, respectively. FSW-welded ARB specimens showed yield strength, tensile strength, and elongation of 230 MPa, 440 MPa, and 11 %, respectively. After T6 treatment, there was an increase in tensile and yield strength of 550 and 310 MPa, respectively, due to the Orowan looping mechanism, which reduced the elongation of the specimen. In conclusion, FSW was suggested as a method of joining the NG/UFG AA2024 alloy sheets while highly retaining the refined microstructure.

STUDY ON RECOVERY OF ALUMINA GRAINS AND FIBERGLASS FROM REJECTED AND USED ABRASIVE DISCS

Kolio Troev — 2025-09-03

A method was developed for the quantitative regeneration of Al2O3 from rejected and spent abrasive discs by pyrolysis. It overcomes the shortcomings of the method described in the literature, namely, the pyrolysis of the abrasive waste takes place without its preliminary crushing and, the pyrolysis takes place at the same speed on the surface of the disc as in volume. This method allows recovering of alumina, fiberglass mesh and cryolite. SEM images of regenerated and virgin Al2O3 show similar sharp edges. The results from the elemental analysis revealed that the content of elements in virgin Al2O3 and in the recovered one are the same. Size and orientation characterization of recovered Al2O3 and virgin Al2O3 is reported. The recovered alumina was used for the preparation of cutting abrasive discs. The examination results revealed that all tested disks meet the corresponding standards.

COMPARATIVE PERFORMANCE OF PEM ELECTROLYZER: STATIONARY VS DYNAMIC MODE

Jordan Iliev — 2025-09-03

This study investigates the performance of a commercial PEM (proton exchange membrane) electrolysis cell, with a working area of 16 cm² and catalyst loading of 2 mg /cm^-2 of IrRuOx on the anode, and 0.5 mg /cm^-2 of 60% PtC and 0.25 mg /cm^-2 of PtB on the cathode side, under constant and dynamic conditions to identify optimal operating modes for practical use. For this purpose, a custom programmable proportional-integrated (PI) direct current (DC) regulator and a pulse-width-modulation (PWM) frequency generator were developed to provide stationary and dynamic modes, functioning as a single system with integrated data logging for cell voltage, temperature, and pressure sensors via a C# program. Experiments confirmed that square wave pulse loading at 1 Hz with 50% duty cycle provides increased efficiency by reducing the cell voltage compared to a continuous DC operation.

ENHANCING REGENERATION SYSTEM CYCLIC STABILITY FOR ALL-IRON FLOW BATTERIES THROUGH NAFION MEMBRANE MODIFICATION WITH A SILICA NANOLAYER

Yaroslav Kolosovskyi — 2025-09-03

This study investigates the impact of modifying a Nafion N115 membrane with a silica nanolayer created from tetraethoxysilane (TEOS) on the performance and durability of an all-iron flow battery. The research aims to enhance electrolyte regeneration and reduce degradation issues commonly encountered in such systems. Potentiometric analysis and cyclic voltammetry were employed to assess the modified membranes' cyclic stability and electrochemical activity of the catalyst. The results demonstrate that the TEOS-modified membrane significantly improves cyclic stability, extending it to ten cycles, compared to just three cycles for unmodified membranes. Moreover, the modification effectively preserves the electrochemically active surface area of the platinum catalyst, thereby enhancing overall system performance and reducing catalyst degradation. The study concludes that the TEOS-modified Nafion membrane offers a viable solution to improve the durability and efficiency of all-iron flow batteries, making it a promising candidate for long-term energy storage applications.

ULTRASONIC-ASSISTED ELECTRODEPOSITION OF SnNi(C) COMPOSITE COATINGS

Katya Ignatova — 2025-09-03

ABSTRACT

By changing various parameters: content of graphite particles, ultrasonic stirring and electrolyte temperature data on the growth rate, elemental composition and morphology of electrodeposited Sn-Ni(C) composites on copper were obtained. The coatings deposition was performed at galvanostatic conditions in gluconate-glycinate electrolyte with pH = 4÷4.5. Graphite powder (type Soft) with a concentration of 1÷4 g L^-1 was introduced into the electrolyte. Coatings deposited under “quiet” conditions are coarse-crystalline and the graphite particles are unevenly distributed. By increasing the temperature to 60 ⁰C, ultrasonic stirring and graphite content in the solution of 3 g L^-1, the coatings become finer-crystalline and smooth. The Ni content increased by about 11 wt.% and това на Sn varies between 44 wt.% to 71wt% in these conditions. When applying ultrasonic stirring and when the graphite content in the solution increases from 0 to 4 g L^-1, the average growth rate of the coating varies around higher limits (from 108 mg cm^-2 h^-1 to 74 mg cm^-2 h^-1 ) compared to " the "quiet" conditions (from 95 mg h^-1 to 44 mg cm^-2 h^-1).

Key words: electrodeposition, graphite particles (C), composite coating, SnNi(C), ultrasonic stirring

THE INFLUENCE OF THE CRUCIBLE AND THE COOLING RATE ON THE STRUCTURE OF GLASSES AND GLASS-CRYSTALLINE MATERIALS IN THE CaO-Na2O-P2O5-B2O3 SYSTEM

Tina Tasheva — 2025-09-03

Batches with composition 47.2B2O3-24.98Na2O-27.54CaO-0.27P2O5 (mol %) were melted in porcelain and corundum crucibles by melt quenching and normal cooling rate techniques. As a result, four different materials were obtained. Powder X-ray diffraction analysis showed that the sample melt in a corundum crucible and melt-quenched was almost fully amorphous, whereas its slowly cooled analogue exhibited near-complete crystallization. Samples prepared in porcelain crucibles, regardless of cooling technique, had predominantly amorphous structures, but two different crystalline phases appeared when the melts were slowly cooled. Scanning electron microscopy revealed distinct microstructural differences between the slowly cooled samples from porcelain and corundum crucibles. Fourier-transform infrared and Raman spectroscopy identified BO3 and BO4 units as the main structural units, likely
interconnected in pentaborate superstructural units. The influence of crucible material on crystallization behavior and phase formation was discussed.

PRODUCTION OF BIOETHANOL FROM CAP TIKUS BY REDISTILLATION

Emma Julien Pongoh — 2025-09-03

Cap Tikus is a traditional drink made from ethanol, which is derived through the distillation of palm sap. In North Sulawesi, it is crafted from the sap of the aren (or seho) tree (Arenga pinnata). Initially, Cap Tikus was consumed primarily by farmers to warm their bodies. However, over time, it has become one of the popular alcoholic beverages in North Sulawesi, particularly among the Minahasa people. It has spread to other regions such as Papua, Kalimantan, and Java. The sap used to make Cap Tikus is harvested from the enau tree. The people of North Sulawesi, especially the Minahasa tribe, have long recognized this sap as the main ingredient for producing Cap Tikus. The process begins with tapping the enau tree to collect the sap. After collection, the sap undergoes fermentation, resulting in a sour liquid known locally as saguer or, more generally, tuck. After approximately ten hours of fermentation, the saguer is distilled to produce Cap Tikus. During distillation, ethanol is obtained from the Cap Tikus. This ethanol is formed through a hydration reaction involving hydrocarbons, where water molecules are added in the presence of an acid catalyst (H+). This process leads to a new secondary metabolite compound derived from naphthalene 1,2'-oxirane, accompanied by a reduction in double bonds or additional reactions.

STUDY OF THE LEACHING PROCESS FOR COPPER FROM THE PRODUCTION WASTE OF THE BALKHASH COPPER SMELTER WITH THE ADDITION OF AN OXIDIZING AGENT

Timur Sadykov — 2025-09-03

The use of metallurgical slags as secondary raw materials is a pressing issue today. The most rational way to get rid of the negative impact of such objects on the environment is the organisation of heap-leaching sulphuric acid solution. The disadvantages of this process (high temperature, duration of dissolution and concentration of the sulphuric acid) are related to the known high chemical stability of metallic copper and the resulting delayed dissolution. The study aims to improve the process of slag leaching at the Balkhash Metallurgical Plant. The main idea is
that the addition of an oxidizing agent - hydrogen peroxide - to sulphuric acid by analogy with uranium leaching will reduce the duration of dissolution and concentration of sulphuric acid, as well as will not require heating. Modern physical and chemical analytical methods were used to identify the products: the composition of metallurgical slag and post-treated waste was investigated by X-ray spectral analysis on the RLM-21 device, and the phase composition was analysed on the D8 Advance device (Bruker). Processing of the obtained diffractogram data and calculation of interplanar distances were carried out using EVA software. Sample interpretation and phase search were carried out using the Search/Match programme with the PDF-2 Powder Diffractometry Database. This paper presents the first results on the effect of hydrogen peroxide on the leaching of copper. The extraction of copper from the test material is analogous to uranium leaching where the addition of an oxidant in the form of 10 % hydrogen peroxide accelerates the leaching process. We increased the copper recovery to 50 % in 63 days of leaching. Oxygen is known to interact with copper in slag only when heated. In our experiment, the sample was oxidised with 10 % hydrogen peroxide solution and leached with 20 % sulphuric acid solution. In our opinion, oxygen interacts with copper through the formation of monosulphuric and nadsulphuric acids, which are stronger oxidants than hydrogen peroxide. Therefore, the process was carried out without additional heating.

IMPROVEMENT AND RESEARCH OF A NEW COMBINED METHOD FOR PRODUCING SCREW FITTINGS USING COMPUTER MODELING

Sergey Lezhnev — 2025-09-03

This paper presents the results of modeling a combined process of radial-shear rolling and pressing in order to obtain a reinforcing profile at different rotation speeds of the screw matrix. The parameters of the stress-strain state in the zones of radial-shear rolling and the formation of a screw profile in the matrix on the surface and axial parts of the workpiece were analyzed. It has been established that the forced rotation of the screw matrix not only helps to increase the process performance, but also plays an important role in preventing the defects formation. The maximum value of the equivalent strain is achieved in a fixed matrix, the higher the rotation speed of the matrix, the lower the values of the equivalent strain. At the same time, in the case of a high rotation speed of the die, the minimum strain level is 10 approximately. Stress state analysis has shown that this deformation scheme creates a high level of compressive stresses, which are dominated by tensile stresses.