3rd Global Conference on Research in Chemistry and Chemical Engineering

Hydrophobic deep eutectic solvents (HDESs) are emerging as versatile, relatively benign, and inexpensive alternatives to conventional organic solvents in a diverse set of applications. In this context, the formation of microemulsions with HDES replacing the oil phase has become an area of active exploration. Because of recent reports on the undesirable toxicity of many common surfactants, efforts are under way to investigate the formation of surfactant-free microemulsions (SFMEs) using HDES as an oil phase. We present SFME formation using HDESs constituted of n-decanoic acid and five (5) structurally different terpenoids [thymol, l(−)-menthol, linalool, β-citronellol, and geraniol] at a 1:1 molar ratio as the oil phase and water as the hydrophilic phase. Ethanolamine (ETA) exhibited the best potential as a hydrotrope among several other similar small molecules. Results showed a drastic increase in water solubility within the HDESs in the presence of ETA. ETA exerted its hydrotropic action at different extent for each DES system via chemical interaction with the H-bond donor (HBD) constituent of the HDES. The optimum hydrotropic concentration (minimum hydrotrope and maximum water retention, XETAOPT) assigned for each DES/ETA/water system and water loading are reported, and the trends are discussed in detail. Ternary phase diagrams are constructed using visual observation and the dye staining method. The area under the single- and multiple-phase regions (assigned in ternary phase diagrams) was estimated. “Pre-Ouzo” enforced by ETA was investigated using dynamic light scattering (DLS) of the DES/ETA/water systems at XETAOPT. A systematic growth in nanoaggregates was observed with the subsequent addition of water in DES/ETA systems while continuously changing the existing microstructure. The presence of a core (oil)–shell (water)-like structure as indicated by the fluorescence response of Nile red in the “pre-Ouzo” region is speculated. We were able to prepare a homogeneous solution of [K3Fe(CN)6] salt in “pre-Ouzo” mixtures with no apparent deviation in the Beer–Lambert law.

The present study is focused on determination of retention behavior of two pairs of isomers from two series of newly synthesized androstane-3-oxime derivatives in reversed-phase ultra-high performance liquid chromatography (RP-UHPLC). The considered compounds possess significant anticancer activity toward various cancer cell lines, therefore the analysis of their physicochemical properties, including chromatographic lipophilicity, is of interest. The analysis method was developed on C18 column. Three mobile phases were used: methanol/water, methanol/acetonitrile/water and acetonitrile/water mixtures. The most significant separation of isomers from 17-picolyl series was achieved in methanol/water mixture (80/20 v/v) considering retention time and capacity factors (logk). The lowest retention time for both compounds was measured in acetonitrile/water mixture, followed by methanol/acetonitrile/water mobile phase. On the other hand, the most significant separation of the isomers from 17-picolynilidene series was achieved in ternary mixture (methanol/acetonitrile/water). The lowest retention of these two compounds was measured also in acetonitrile/water mixture. Considering in silico lipophilicity measures, which appeared to be identical for both isomers in both pairs, the determined chromatographic lipophilicity, estimated in the applied chromatographic systems, is better parameter for discrimination of the analyzed isomers. Acknowledgement: The present research is supported by the project of Provincial Secretariat for Higher Education and Scientific Research of AP Vojvodina (Molecular engineering and chemometric tools: Towards safer and greener future, No. 002902513 2024 09418 003 000 000 001 04 002).

In the present study in silico ADMET properties of different classes of pesticides were calculated in order to characterize these compounds in the domain of their absorption, distribution, metabolism, and excretion–toxicity. The pesticides cover different groups of insecticides, herbicides, fungicides, rodenticides and acaricides. In silico ADMET descriptors were calculated and used for classification through principal component analysis. The obtained model was described by five principal components with eigenvalue higher than 1: 5.01, 3.88, 2.49, 1.23 and 1.04, covering 85.36% of variance in total. From the scores plot and along the first principal component following descriptors contributed the most regarding the compounds positioning: FeSSIF (simulated intestinal fluid in fed state, -0.9432) and FaSSIF (simulated intestinal fluid in fasted state, -0.9432). The loadings plot indicated that almost all compounds were positioned in one group positioned on the positive end of axis. On the negative end of axis following herbicides were positioned: 2,4-DB, MCPB and dinoseb as compounds with the higest values of FaSSIF (0.50-068) and FeSSIF (1.46-1.66). The use of ADMET molecular descriptors coupled with principal component analysis provided useful information about studied compounds characteristics and grouping. Acknowledgement: The present research is supported by the project of Provincial Secretariat for Higher Education and Scientific Research of AP Vojvodina (Molecular engineering and chemometric tools: Towards safer and greener future, No. 002902513 2024 09418 003 000 000 001 04 002).

The oxygen reduction reaction (ORR) is crucial for development of fuel cells, which are one of the most promising sources of electricity. However, despite many years of research, mechanism of the reaction, as well as the rate-determining step (RDS) remains unclear, even at platinum electrode which is the most efficient catalyst for this reaction so far. The ORR process is also affected by formation of platinum oxides, which reduce ORR efficiency by blocking the catalyst surface. Developed capacitance-charge analysis is based on Dynamic Electrochemical Impedance Spectroscopy (DEIS) technique, which allows obtaining instantaneous impedance spectra during cyclic electrode polarization. Implementation of capacitance-charge analysis provides differential capacitance spectra and, for the first time, charge spectra during electrode polarization. Capacitance spectra provide a distinction between the electrical double layer (EDL) capacitance and the pseudocapacitance generated during ORR, formation and reduction of platinum oxides. The charge spectra allow analogous distinction of the charges associated with the EDL capacitance and pseudocapacitance. Thus, the capacitance-charge analysis can determine contribution of the EDL capacitance and pseudocapacitance to the total capacitance, and analogously determine contribution of the charges associated with these capacitances to the total generated charge. Furthermore, shape of the capacitance and charge spectra allows identification of the step controlling rate of the overall process. The presentation will reveal results of oxygen electrochemistry studies on a platinum electrode in alkaline environments during cyclic polarization of the electrode in potential ranges covering formation and reduction of platinum oxides and ORR.

Impedance techniques are an integral part of electrochemical research. Among them, Electrochemical Impedance Spectroscopy (EIS) is one of the most widely used and wellestablished methods. Its modernized variant, Dynamic Electrochemical Impedance Spectroscopy (DEIS), enables quasi-stationary measurement of non-stationary processes and has become a foundation for further developments in impedance-based diagnostics. This presentation explores an alternative approach to DEIS spectrogram analysis. Traditionally, impedance is examined as a function of frequency. Here, we propose treating impedance as a function of both frequency and another independent variable, such as time, current density, or potential. This perspective allows mathematical operations to be applied to entire spectrograms, offering new opportunities for interpretation. Based on this method, we introduce two new concepts: differential impedance and relative impedance. These approaches provide enhanced sensitivity to dynamic changes in the measured system and allow for the observation of subtle variations that may not be visible through conventional analysis. The presentation will cover the theoretical background of these concepts, procedures for generating differential and relative impedance spectrograms, and challenges commonly encountered in data processing. Practical solutions to these issues will be discussed, along with the potential applications of both impedance types in the study of electrochemical systems. The benefits of incorporating these novel forms of impedance into experimental analysis will also be highlighted.

The aim of this study is to develop an adsorption separation process using Aspen Adsorption. The separation process has the primary focus on capturing methane gas (CH₄). Therefore, Extended Langmuir 3 adsorption model was developed for the system. The model simulation breakthrough time and trends show a significant agreement with the experimental work where 80s of saturation time achieved i.e., the model was validated and accurately reproduced real adsorption behaviour, strengthening its credibility. The simulation model could exactly estimate the experimental mass transfer coefficient of (0.195 s⁻¹) for methane adsorption on activated carbon. Moreover, the separation process was optimized by studying the effect of bed design parameters on the CH₄ adsorption. The results revealed that increasing bed height from 1m to 10.5m and from 1m to 7m for Activated Carbon (AC) and Zeolite beds, respectively, at a fixed diameter of 0.037m, remarkably improved the methane retention time, reaching to maximum of 650s for AC and 450s for Zeolite. Furthermore, increasing the bed diameter from 0.0370.1m causes a direct increase in the breakthrough saturation time from 150s to 800s, respectively, with 0.91 kmol/kmol concentration. The bed diameter was systematically adjusted with changes in bed height to ensure optimal adsorption performance. Thus, the breakthrough curve analysis indicates optimal performance, with AC completing the passage of CH₄ at ~2450s, while Zeolite 5A reached methane breakthrough full saturation at ~1800s, hence demonstrating a significantly higher capacity for CH₄ adsorption. The research emphasizes its potential as a predictive and industrially relevant tool for mitigating greenhouse gases emission.

The COOL+ Process is a method designed for lithium extraction from spodumene at moderate temperatures as well as valorization of the leaching residue, to achieve zero waste. It is an innovative and environmentally friendly process employing CO2 in aqueous media, avoiding the use of strong acids to minimize environmental impact. The process was validated in a lab-scale where key variables, such as Na2CO3 dosage and mixing, calcination temperatures and duration, particle size, liquid-to-solid ratio, and reactor filling, were systematically optimized to maximize Li recovery. The challenges lie in the downstream of the process. Compared to the traditional acid leaching process, only a small amount of Al and Si is mobilized. The majority of Si was removed with the addition of MgO, and the main impurity, co-mobilised Na, is removed by washing. The solid residue, separated by filtration after supercritical CO2 digestion, contains high amounts of nepheline, a precursor for the ceramic and cement industry. The residue can also be used as filler for geopolymer production. The optimized process recovers more than 90 % of Li from primary sources (spodumene and petalite), yielding battery-grade Li2CO3 as the final product. This study represents a comparison between lab-scale and pilot-scale, where partial pilot plant validation of key parameters serves as a precursor to full-scale implementation. The findings demonstrate that the COOL+ Process is technically viable and holds strong industrial potential, laying the foundation for a sustainable lithium production route from minerals.

Due to the attractive properties as excellent thermal and chemical resistance, high visible light transparency, and high thermal diffusion coefficient, transparent ceramic is probably an ideal matrix of luminescent materials. By introducing different lighting dopants, the luminescent ceramics with different properties have been widely used. However, the high temperature required to prepare transparent ceramic by conventional methods could be as high as 1873 to 2573K, which is an obstacle for controllable synthesis and well protection of the embedded materials. Thus, the preparation technologies of the luminescent ceramics are facing new challenges because of these volatile and unstable lighting dopants that are easy to be decomposed. This report introduces a novel, facile route for the preparation of stable monolithic ceramic-based luminescent materials, which can be widely used to introduce temperature-sensitive functional materials into the transparent matrix, by Spark Plasma Sintering(SPS). Furthermore, the research progress and superiority of SPS technology used to develop the light-emitting ceramics containing nanocrystals, perovskite, and phosphors. Owing to the fast sintering procedure of SPS with relatively low temperature, the size, shape, surface topography, and optical properties of the dopants in luminescent ceramics are found to be similar to those of untreated counterparts, which means that the sensitive dopants can be completely protected.

Non-recyclable plastic waste, particularly from textile blends with complex multi-material fiber compositions, poses a persistent challenge to circular economy strategies. Conventional disposal methods rely heavily on incineration, emitting approximately 2.5 kg of CO₂ per kilogram of plastic burned, and landfill, which results in permanent material loss. Our team worked to address this challenge by developing a novel insect-based biorefinery using Galleria mellonella larvae, which have the unique capacity to digest and transform plastics, including non-recyclable textile-derived polymers, into valuable bioproducts such as proteins, lipids, and chitin. Our team conducted controlled feeding trials comparing survival, larval mass, and pupation success of insects reared on polymeric substrates with those starved or fed on conventional oat bran. Results demonstrate that survival, growth, and pupation on plastics are consistently higher than in starving controls and comparable to oat bran, highlighting the larvae’s adaptability and metabolic efficiency after a short acclimatization period. The project also advances engineering aspects by piloting a biorefinery system to process polymer mixtures and co-polymers separated from post-consumer textiles, while optimizing rearing and environmental parameters to maximize conversion efficiency. By fixing up to 67% of CO₂ per kilogram of waste processed, the developed biorefinery offers a disruptive pathway for valorizing difficult-to-recycle plastics, contributing to carbon mitigation, resource recovery, and circular textile industry transformation.