Recent Innovations in Chemical Engineering - Volume 18, Issue 4, 2025

Supercapacitors have shown substantial promise in electrochemical energy storage devices, where porous carbon materials demonstrate exceptional potential applications in their electrodes owing to their large specific surface area, high electrical conductivity, and rationally tunable pore architectures.

Sodium lignosulfonate and graphene oxide-based porous carbon materials (LC/rGO) were prepared and characterized. The electrochemical performance of the samples was investigated with three-electrode configurations.

LC/rGO demonstrated mesoporous architecture and excellent electrochemical performance. The kinetic analysis on the electrochemical properties of the materials revealed an electric double-layer capacitance dominated energy storage mechanism.

XRD and Raman analysis on the structures of the as-prepared carbon materials suggested a relatively high degree of defects and disorder. Investigations on the morphology, the pore size distributions and the surface chemistry of the samples demonstrated that the materials had a high specific surface area, mesporous structures and multi-atomic doping of nitrogen and oxygen functional groups. All these features could be taken into account for the high electrochemical performance of carbon.

LC/rGO as an electrode material demonstrated a high specific capacitance of 296 F g^-1 at 0.1 A g^-1 and outstanding cycling stability with 97% of the initial capacitance after 10,000 cycles at 5 A g^-1 in a 6 M KOH electrolyte. The assembled symmetric supercapacitor using the as-synthesized materials exhibited energy density of 10.6 Wh kg^-1 at 300 W kg^-1 and cycling stability of 95% capacitance after 10,000 charge-discharge cycles, promising for supercapacitor applications.

In industrial processes, some impurities in industrial liquids are usually adsorbed on the bubble interface, thus affecting the bubble interface mobility. Sometimes, additives are also intentionally added to industrial liquids to optimize the hydrodynamic properties of discrete bubbles and improve industrial efficiency. Therefore, an in-depth study of the hydrodynamics of discrete bubbles in impure liquids is of great significance. The objective of this study is to explore the dynamics of bubble rising in ethanol-aqueous solutions, with the aim of understanding the relationship between bubble rising dynamics and the ethanol mass fraction.

The effect of the free-rising motion of individual bubbles was studied by controlling the ethanol mass fraction and bubble size, and images of the bubbles were recorded with the aid of a high-speed video camera when the rising motion of the bubbles reached an approximate steady state.

When the equivalent diameter of the bubble was fixed, the ascending trajectories of bubbles changed from spiral lines to straight ones as the ethanol mass fraction increased. The larger the equivalent diameter of bubbles is, the higher the transitional mass fraction of the bubble ascending trajectory is. For single bubbles with the same equivalent diameter, as the ethanol mass fraction increased, the terminal ascending velocity of bubbles approximately decreased first and then increased; however, the aspect ratio of single bubbles initially increased and then decreased. There were three concentration regions corresponding to the apparent changes in the terminal ascending speed and the terminal aspect ratio of single bubbles as the ethanol mass fraction increased.

The impact of the ethanol mass fraction on bubble rising dynamics, including the bubble equivalent diameter, terminal ascending velocity, and ascending trajectory, was thoroughly analyzed and discussed. The related mechanism of bubble dynamics was also discussed.

The bubble ascending dynamics were found to be related to ethanol mass fraction, and the dependence of the ascending dynamics of single bubbles on ethanol mass fraction was complex. The bubble terminal ascending speed did not change monotonically as the ethanol mass fraction increased.

This paper has focused on the preparation of a high-temperature composite material from naturally available beach sand zircon minerals.

Initially, zirconia was prepared from natural zircon minerals through a chemical route. Further, synthetic zircon was prepared by the calcination of zirconia and silica. The product was characterized by examining the water absorption capacity, apparent porosity, dielectric strength, XRD, chemical analysis, TEM, electrical resistance, relative density, and thermal stability properties. The insulation properties were studied by applying synthetic zircon coatings on base materials. The analysis of the results was carried out by using an artificial neural network (ANN).

The dielectric strength was found to be 10.2 kV/mm at a temperature of 1500°C. XRD analysis confirmed the occurrence of tetragonal zircon (t-zircon), which is thermally stable up to 1500°C.

TEM results confirmed the synthetic zircon to lie in the nano-size range. XRD analysis confirmed that the synthesized zircon retained ~100% of the tetragonal zircon phase even after calcination at 1500°C, indicating excellent thermal stability at that temperature. The electrical resistance of synthetic zircon was found to be in the range of 200-210 MΩ. The comparative study confirmed synthetic zircon to have the potential to be used for high-temperature structural and functional applications, including its preliminary use in thermal barrier systems.

The purpose of this work is to investigate the molecular interactions in binary mixtures of polyethylene glycol (PEG) and ethanol at different temperatures (25°C, 35°C, 45°C, and 55°C) and concentrations (5%, 10%, and 15%). The goal is to comprehend how these factors affect important physicochemical and thermoacoustic characteristics that are pertinent to coatings, drug delivery systems, and material formulation.

At a steady frequency of 4 MHz, the ultrasonic velocity, density, and viscosity of PEG-ethanol solutions were measured. Internal pressure, free volume, available volume, Rao's constant, Wada's constant, molar volume, and surface tension were among the thermodynamic and acoustic parameters that were computed from these measurements. To guarantee accuracy, calibrated instruments and standard procedures (ASTM) were used.

The findings showed that while free volume and molar volume increased with temperature, ultrasonic velocity and density decreased. Rao's and Wada's constants, as well as internal pressure, exhibited a declining trend as the temperature rose, suggesting that intermolecular interactions were becoming weaker. On the other hand, higher PEG concentrations improved hydrogen bonding, which raised the interaction constants, surface tension, and ultrasonic velocity. All of these patterns point to a significant reorganisation of the molecular structure in the PEG-ethanol system that is dependent on temperature and concentration.

Internal pressure in PEG-ethanol mixtures rises with temperature as molecular vibrations intensify, but falls with increasing PEG concentration because PEG disrupts the hydrogen-bond network in ethanol. On the other hand, increased molecular spacing due to polymer addition and thermal expansion is indicated by the rise in free volume, available volume, and molar volume with concentration and temperature. Rao's and Wada's constants also rise in both scenarios, indicating variations in density, sound speed, and molecular packing that affect the mixture's thermodynamic and acoustic properties.

The study demonstrates that molecular interactions in PEG-ethanol mixtures can be successfully revealed by thermoacoustic and ultrasonic analysis. The trends demonstrate how PEG can form hydrogen bonds, which have a significant impact on the behavior of solutions. These results provide important new information for designing and optimising the stability of polymer-based solutions in material science and pharmaceutical applications.

Human activities during the last century have dramatically increased CO2 emissions, prompting scientists to develop both emission reduction techniques and profitable business opportunities. This research improves the production process for generating methanol fuel from captured CO2 while simultaneously reducing atmospheric CO2 levels and creating marketable products.

The simulation process, based on Aspen Plus software, develops a precise method to absorb CO2 from thermal power plant flue gases. The production of hydrogen, which drives methanol synthesis, depends on water electrolysis powered by carbon-free electricity. This study examines outcomes generated by using two different catalyst systems, Cu/ZnO/Al2O3 and In2O3, throughout the plant operation. Financial feasibility is determined by conducting an extensive economic plant evaluation, which includes a Return on Investment analysis, an Internal Rate of Return calculation, and assessments of Net Present Value and Payback Period.

It is found that the process utilizing the In2O3 catalyst is more efficient than the Cu/ZnO/Al2O3 catalyst, particularly when H2 is sourced from different renewable energy sources.

These findings suggest that the choice of a proper catalyst plays a vital role in the yield and economics of the methanol process. The benefits of In2O3 are linked to the current strong focus on combating climate change by fully integrating renewable energy into the grid and promoting sustainable chemical production worldwide. While simulation data were used for the study, experimental validation and scalability studies are still needed.

Consequently, the synthesis process using the In2O3 catalyst emerges as a sustainable and environmentally benign approach for methanol production.