Journal of the Serbian Chemical Society

Optimisation of the controlled release of valsartan via cellulose acetate butyrate and poly(butylene succinate) microspheres: Influence of formulation conditions

2025-09-08T16:09:04+02:00

This study investigates the formulation of valsartan-loaded cellulose acetate butyrate (CAB) microspheres, prepared via solvent evaporation microencapsulation, to evaluate their in vitro release behavior and the influence of formulation parameters. The study examined the effects of stirring speed, stabilizers and matrix materials on particle size and drug release. Increasing stirring speed reduced particle size but also led to higher valsartan loss, reducing encapsulation efficiency. Using the surfactant polylactic acid resulted in smooth, spherical and porous microspheres that enhanced controlled release. In contrast, using Tween 80 led to irregular particles with rough surfaces and larger pores that accelerated drug release. Including poly(butylene succinate) in the matrix resulted in smaller microparticles forming and a significantly higher rate of valsartan release. These findings emphasize the importance of optimizing formulation parameters and excipients to control drug release characteristics and enhance drug delivery system performance.

A novel Zn(Ⅱ) coordination compound exhibits selective and sensitive detection of Fe3+ and acetylacetone

2025-08-25T10:47:18+02:00

Pyridine derivatives have strong coordination ability, tunable electronic, optical properties and excellent stability as ligands. Their substituent engineering and conjugation extension provides an ideal platform for the construction of efficient fluorescent probes, catalysts and biological functional materials. Based on this, a new coordination compound [Zn(phen)(L)(H₂O)]·4H₂O was synthesized under solvothermal conditions used 1,10-phenanthroline (phen), 3-carboxy-1-carboxymethyl-2-oxidopyridinium (H₂L) and Zn(Ⅱ). The crystal structure and composition of the coordination compound were confirmed by single crystal X-ray diffraction and thermogravimetric analysis. Structural analysis confirmed by single crystal X-ray diffraction reveals its unique coordination geometry. In addition, it exhibits significant luminescence, making it a candidate for sensing applications. The luminescence and sensing properties of the coordination compound were investigated in detail. The K_sv values for the detection of Fe³⁺ and acac were found to be 3.29×10 ⁵ and 6.67×10⁵ M^-1, which confirmed the high and efficient sensing ability of the synthesized sensor.

Investigation of corrosion causes and failures in the interior metal components of an automobile

2025-04-01T07:43:33+02:00

The extent of corrosion and the underlying causes of damage to the interior metal components of a one-year-old automobile from a known brand, owned by a rental car company in Serbia, were investigated. The vehicle’s interior, including upholstery and carpeting, showed no chemical spills or other damage. The solution obtained after rinsing a carpet sample from the car floor exhibited neutral pH. The corrosion behavior of the analyzed samples was determined using electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and linear sweep voltammetry (LSV, Tafel method). X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses showed that corrosion products taken from corroded steel parts contain akaganeite β-FeO(OH) and iron (II) chloride. FTIR analysis of the organic coating revealed that the applied epoxy layer was insufficiently crosslinked, making it permeable to moisture and chloride ions. Electrochemical corrosion measurements on steel with a similar chemical composition demonstrated an increased corrosion rate in a solution containing dissolved corrosion products compared to a reference solution. This accelerated corrosion was attributed to the acidity of akaganeite and iron (II) chloride, formed due to the vehicle’s exposure to a humid and chloride-rich environment.

Comparative study of micellization and surface properties of cationic and anionic surfactants in acetonitrile–water mixed media

2025-08-05T14:23:56+02:00

A comparative study was conducted to investigate the micellization behaviour, surface properties and wettability of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the anionic surfactant sodium dodecyl sulfate (SDS) in acetonitrile–water (ACN–water) mixed media. Surface tension and contact angle measurements were performed in pure water and ACN–water mixtures (0.10, 0.20 and 0.40 volume fractions of ACN) at 298.15 K to determine the critical micelle concentration (CMC), surface excess concentration (Γ_max), minimum surface area per molecule (A_min), micellar surface pressure (π_CMC) and packing parameter (P). Contact angle measurements were used to assess wettability on borosilicate glass surfaces. Results indicate that increasing ACN content leads to an increase in CMC, suggesting reduced micellization feasibility in less polar media. Surface excess concentration decreases with higher ACN fractions, while minimum surface area per molecule increases, indicating looser molecular packing at the air/solution interface. Contact angle measurements reveal a decrease in wettability with higher ACN content, demonstrating enhanced surfactant adsorption at the solid-liquid interface. Additionally, micellar surface pressure and packing parameter decline with increasing ACN concentration. These findings underscore the critical role of solvent composition in modifying surfactant aggregation and interfacial behaviour.

Computational insights into the inhibitory potential of dihydroorotate dehydrogenase by natural compounds in Artocarpus champeden as antimalarial agents

2025-07-17T07:26:55+02:00

Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) is a crucial target for the development of antimalarial drugs, as it plays a significant role in inhibiting the growth of parasites by disrupting the production of pyrimidines in the bloodstream. Artocarpus champeden is known to contain prenylated flavonoids with potential antimalarial activity. This study aims to explore the chemical interactions of active compounds found in A. champeden through an in silico approach. Nine compounds were docked into PfDHODH (PDB ID: 6I55), and their stability was subsequently assessed using molecular dynamics simulations. Molecular docking results indicated that compounds C1, C5 and C6 emerged as the most promising candidates, exhibiting binding affinities of –37.80, –35.28 and –34.44 kJ/mol, respectively. His185 and Arg265 were found to be key binding residues, interacting with these compounds in a manner similar to DZB, the control ligand. A 50-ns molecular dynamics simulation further confirmed the stability of these compounds throughout the simulation. Moreover, the examination of hydrogen bond occupancy demonstrated that compound C1 consistently engaged in hydrogen bonding interactions with His185 and Arg265 throughout the simulation.

Effect of pyrolysis temperature and time of Robusta coffee husk on yield and product characteristics

2024-12-02T01:35:45+01:00

The utilization and recycling of biochar from coffee husks is a global issue, as 1.8 Mt of coffee husks were produced in 2023. The mechanism of coffee husk pyrolysis and the factors influencing pyrolysis temperature and time on the properties of biochar were studied. Coffee husks were pyrolyzed at 350, 450 and 550 °C and held for 30, 45 and 60 min to form biochar, the physicochemical properties of biochar were characterized by thermogravimetric analysis, X-ray diffraction, surface morphology and Fourier-transform infrared spectroscopy. The pyrolysis of coffee husks occurs due to dehydration, decomposition and carbonization reactions. Pyrolysis temperature and time directly affect the yield of biochar, pH, fixed carbon, volatile matter, ash, nitrogen, phosphorus and potassium contents. Furthermore, pyrolysis temperature has a greater influence on the properties of biochar than pyrolysis time. The high potassium content of biochar can significantly replace conventional potash fertilizers. Therefore, biochar plays a dual role as a liming agent and can be used as a soil additive.

Kinetic and equilibrium comparison of methylene blue and basic blue 41 adsorption by silica fume

2025-02-23T17:29:50+01:00

The complex molecular structures of synthetic dyes are not easily removed from water, so it is essential to treat dye pollutants before they enter the aquatic environments. In this study, cost-effective industrial waste silica fume (SF) was used as an adsorbent to investigate the adsorption of methylene blue (MB) and basic blue 41 (BB-41). The structure of the silica fume adsorbent was characterized using the FESEM technique, which confirmed that SF has a porous structure. The adsorption of these cationic dyes was examined using kinetics models (pseudo-first-order and pseudo-second-order) and isotherm models (Langmuir, Temkin, Dubinin–Radushkevich and Freundlich), and the results obtained were compared. Based on the findings, the adsorption process of MB and BB-41 on SF followed pseudo-second-order kinetics. The adsorption of MB and BB-41 on SF followed Freundlich isotherm model. According to Langmuir isotherm data, the maximum adsorption capacity for BB-41 and MB was found to be 41.95 and 189.31 mg/g, respectively.

Development of biopolymer encapsulated enzyme for efficient acetaminophen degradation

2025-08-15T12:19:57+02:00

The study aimed to investigate the effectiveness of partially purified turnip (Brassica rapa) peroxidase immobilized in calcium alginate for degrading paracetamol, also known as acetaminophen (AAP), a commonly used over-the-counter analgesic and antipyretic. The encapsulation of peroxidase was optimized to minimize enzyme leakage and maintain maximum activity by adjusting the sodium alginate content, enzyme loading, and calcium chloride concentration. The optimal conditions for encapsulating peroxidase in calcium alginate matrices with the best retention and efficiency were determined to be 1.3 U/mL enzyme loading, 1.5 % sodium alginate, and 0.05 M calcium chloride concentration. This research focuses on investigating the efficacy and application of immobilized turnip peroxidase in degrading pharmaceutical effluents, specifically targeting paracetamol. The results revealed the maximum degradation of AAP at a pH of 2.0 and a temperature of 30 °C, with paracetamol and hydrogen peroxide concentrations of 1g/L and 1.2 mol/L, respectively, resulting in a 97 % yield using the stabilized peroxidase. The study also determined the kinetic characteristics of the enzymatic reaction, such as the maximum rate and the Michaelis–Menten constant. Furthermore, the stabilized enzyme can be utilized multiple times, specifically up to three occasions, in ideal conditions, while maintaining 80 % of its ability to degrade AAP.

A CFD investigation of the performance of stirred tanks

2025-06-30T16:19:31+02:00

Rushton turbine was employed in this study to numerically analyze the fluid flow it generates within a stirred tank. The topology of the resulting flow was found to be strongly dependent on several parameters, including the geometric configurations of the system and the properties of the moving fluids. The governing equations, based on the k–ε model, were solved using the finite volume method. Velocity field profiles, streamlines and vortex sizes were analyzed for several geometries, varying the number of blades from 6 to 12 and others. A comparison was also conducted to evaluate the effect of the number of stirring mobiles used to mix the fluid (single stage, two stages and three stages), as well as the influence of the spacing ratio between the different stirrers. Finally, our numerical simulation procedure was validated through comparing the results obtained with experimental work available in the literature, showing good agreement between the different approaches.