Chemical Engineering & Technology

The need for affordable and clean energy calls for biodiesel production from renewable sources. Thus, corrosion rate (CR) examination of diesel engine components in biodiesel is vital. This study examined the corrosion behavior of copper coupon (CC) in diesel fuel blended with biodiesel synthesized from waste cooking oil. Characterization and CR evaluation were executed at immersion time, temperature, blending ratio, and agitation of 30–60 days, 30–50 °C, 10–30 (v/v) %, and 110–130 rpm, respectively. Physicochemical properties of blended biodiesel changed after CC corrosion. Minimum CR of 0.002537 mm y⁻¹ was recorded at 30 days, 30 °C, 20 (v/v) %, and 110 rpm, respectively. The developed Taguchi model was excellent. R², RMSE, MAE, SEP, and AAD were 0.9992, 0.0004156, 0.0003022, 0.01695, and 0.6855, respectively. Pits formation, the presence of Cu, C, and O on CC surface, and 10.83 ppm Cu ions in blended sample were noticed at highest CR.

The efficient enantioseparation of racemic compounds remains a critical challenge in pharmaceutical manufacturing. This investigation examines the crystallization‐induced diastereomeric transformation (CIDT) of (S)‐ketoprofen‐(S)‐phenylethylamine salts as a strategy for obtaining high‐purity diastereomeric salts. Solubility phase diagrams were constructed for diastereomeric salts. A double salt system was identified, and a solvent system of 2‐propanol and heptane (50:50 wt.%) was optimal for crystallization. Among the seven base catalysts screened, DBU (1,8‐diazabicyclo[5.4.0]undec‐7‐ene) was found to be the most effective. Optimization studies demonstrated that 5–10 mol% DBU provides the highest purity (98.8 %) with 26.2 % yield. These results provide insights into the dual role of DBU as a catalyst (forming mixed salts) and cosolvent, influencing yield. The findings highlight CIDT as a robust method for the enantioseparation of diastereomeric salts in pharmaceutical applications.

Biphasic solvents show promise for CO2 capture due to lower energy consumption but face challenges like high regeneration energy and phase separation instability. This study introduces a biphasic aqueous solvent system with triethylenetetramine (TETA) and tetramethylethylenediamine (TMEDA). The effects of TETA:TMEDA ratios on CO2 absorption, viscosity, density, and phase separation were tested at various temperatures and compared to 5 M mono‐ethanolamine (MEA). The optimal 1.5 M TETA:2.5 M TMEDA at 40 °C captured 0.72 mol CO2 mol⁻¹ amine, with 84 % CO2 in the lower phase. Desorption at 90 °C achieved 0.43 mol CO2 L⁻¹, improving cyclic capacity by 62 % over MEA. The solvent required 2.77 GJ t CO2⁻¹ for regeneration, 22 % less than MEA. Nuclear magnetic resonance (NMR) analyses elucidated reaction mechanisms and phase behavior. Stability was confirmed by over 10 absorption–desorption cycles.

The development of high‐performance solid adsorbents for CO2 capture is crucial for reducing carbon emissions and combating climate change. Density functional theory (DFT) has been widely used to explore the adsorption mechanisms of solid adsorbents, but its computational cost limits large‐scale material screening. Machine learning (ML) as a data‐driven approach promotes materials development. This paper reviews the synergistic integration of DFT and ML in the design and development of solid amine adsorbents, metal‐organic framework materials, and calcium‐based adsorbents. With high‐quality training data generated by DFT, ML models can effectively predict material properties. In addition, the integration of ML accelerates high‐throughput screening, significantly improving the speed and accuracy of material discovery. This review summarizes recent advances and perspectives in the application of computational methods for the rational design of solid adsorbents.

This study investigates the thermo‐kinetic behavior and product characterization of Tamanu seed (TS) and waste polypropylene (PP) through thermogravimetric analysis (30–900 °C at 5, 10, and 20 °C/min), batch pyrolysis (400–550 °C), and pyrolytic oil analysis (Fourier transform infrared [FTIR] and gas chromatography–mass spectrometry [GC–MS]). Co‐pyrolysis of TS and PP lowered the thermal degradation temperature of PP. The thermal degradation of TS exhibited the activation energy of 165 kJ mol⁻¹, following an F2 mechanism, whereas PP showed the activation energy of 293 kJ mol⁻¹ with an F1 mechanism. The TS–PP blend exhibited the activation energy of 280 kJ mol⁻¹ and followed a D1 mechanism. The blend reduced the Gibbs free energy to 765.29 kJ mol⁻¹, compared to 766.87 kJ mol⁻¹ for TS and 830.46 kJ mol⁻¹ for PP alone. Co‐pyrolysis improved the yield and fuel properties of the pyrolytic oil, demonstrating a sustainable and effective strategy for converting biomass and plastic waste into valuable biofuels, contributing to waste management and energy recovery.

To attempt a selective extraction from a cannabigerol (CBG)‐rich Cannabis cultivar, supercritical fluid extraction was tried, operating at 18 MPa and 40 °C. In the first set of experiments, a fractional extraction scheme was used to favor the separation between the cannabinoid extract and paraffinic waxes: global and CBG yields were equal to 4.8 % and 3.8 % w/w, respectively, leading to an overall CBG concentration in the extract up to 79 %. However, GC–MS traces showed that CBG also tended to precipitate in the refrigerated separator together with paraffinic waxes, due to CBG steric configuration that is very similar to the one of paraffins. Therefore, non‐fractional extraction experiments were selected, by‐passing the refrigerated separator. Operating in this manner, a selective extraction was obtained with improved global and CBG yields up to 5.3 % and 4.4 % w/w, respectively, and a CBG concentration of 83 % in the extract.

The Fischer–Tropsch synthesis (FTS) is a highly exothermic reaction often conducted in multi‐tubular fixed‐bed reactors. Pore diffusion limitations within the catalyst particles are typically viewed as detrimental due to reduced reaction rates. However, this study demonstrates that these limitations can provide significant benefits in terms of reactor stability and performance. Using a 2D numerical reactor model, we explore the influence of pore diffusion on temperature profiles, conversion, and thermal runaway behavior under realistic operating conditions. Results reveal that pore diffusion reduces the apparent activation energy, effectively mitigating thermal sensitivity and increasing the allowable level of reaction temperature. Consequently, higher CO conversions can be achieved safely compared to an idealized scenario without pore diffusion limitations. Hence, pore diffusion limitations, rather than being a disadvantage, act as a stabilizing factor in FTS reactors.

Here AgNPs were synthesized from leaf extracts of Cymbopogon citratus (lemon grass), along with their antibacterial and antidiabetic properties. The reduction rate of AgNPs at 215, 235, and 302 nm was faster, and UV–vis tests were used to verify colloidal manufacture of AgNPs. Nevertheless, TEM revealed that the particles used in the study were spherical nanoparticles with a 40 nm size range. AgNPs may surround amines based on observations of a peak at 1531 cm⁻¹, because ─NH2 symmetric stretching and N─O bonds are common in nitro compounds. Compared to leaf extract, AgNPs exhibit C─X stretching vibrations at 663 cm⁻¹, indicating that alkyl halide groups are present. Experimental data revealed that the indexed peak has a lattice parameter of 4.0957. Besides gram‐positive bacteria, AgNPs are also capable of killing multi‐drug‐resistant bacteria as well. As concentrations of AgNPs were increased, the percentage of inhibition activity increased, indicating that they are effective at controlling diabetes.

This research explores entropy generation in the two‐dimensional flow of MHD (Al2O3–TiO2/H2O) hybrid nanofluid over an exponentially stretching sheet within a porous medium. The study incorporates chemical reaction, thermal radiation, and Joule heating into the concentration and energy equations, which are thoroughly analyzed. The governing PDEs are transformed into nonlinear ODEs using similarity solutions and solved numerically with the bvp4c solver in MATLAB. The study examines the effects on flow profiles and key engineering parameters. Results show that increasing Brinkman and Reynolds numbers produces contrasting trends in entropy generation and the Bejan number. A stronger magnetic field and porous medium increase skin friction by 2.18 % in hybrid nanofluids. An enhanced Eckert number combined with radiation raises heat transfer by 5 % compared to conventional TiO2/H2O. The mass transfer rate increases by over 1.5 % with a rising reaction factor in Al2O3–TiO2/H2O.

This study investigates Ag‐doped Fe3O4 nanofluids for enhanced convective heat transfer. Nanoparticles were synthesized using ultrasound‐assisted and minireactor‐based methods, characterized through analytical techniques, and dispersed in water to evaluate their stability and thermal conductivity. A lab‐scale setup was used to analyze convective heat transfer, pressure drop, and friction factor in a pinched tube, an advanced heat transfer system. Results demonstrate a significant Nusselt number increase from 22.886 to 62.365 at a Reynolds number of 6160 ± 75 when 0.02 vol.% of minireactor‐synthesized Ag‐doped Fe3O4 nanoparticles were added to water. These findings highlight the potential of these nanofluids for improving thermal performance in practical applications.

This study investigates the breakup behavior of liquid jets in both linear and rotary atomization using numerical simulations based on the volume of fluid (VOF) method. The results reveal the significant role of gas–liquid interactions, with jet curvature, driven by Coriolis and centrifugal forces, playing a crucial role. Various breakup patterns, including primary and satellite droplets, emerge due to nonlinear instabilities. Simulations accurately reproduce experimental droplet size distributions, highlighting the importance of gas–liquid interactions and jet curvature in rotary atomization.

This study presented a superhydrophobic polytetrafluoroethylene hollow fiber membrane (PTFE‐HFM) modified with a PDMS/nano‐SiO2 composite coating for high‐temperature waste oil purification. By integrating interfacial engineering and thermal stabilization, the membrane achieved tunable hydrophobicity (water contact angle up to 158°) and hierarchical roughness via controlled SiO2 loading. At 2 wt.% SiO2, the optimized membrane exhibited exceptional performance: superior high‐temperature permeation flux (162.38 L·m⁻²·h⁻¹·bar⁻¹ at 150 °C), and remarkable anti‐fouling stability (flux attenuation reduced to 7.35 % over 200 h). The synergistic PDMS/SiO2 coating enhanced mechanical robustness while maintaining structural integrity under dynamic conditions. The membrane demonstrated efficient separation of water‐in‐oil emulsions (96.78 % rejection) and sustained operational stability in high‐temperature environments, offering a promising solution for industrial oily wastewater treatment. image

The present work demonstrates the development of an economical and user‐friendly “copper rods” sensor for detecting malathion. Differential pulse voltammetry (DPV) was performed to observe the inhibition ratio at various concentrations of malathion, which increases with an increase in malathion concentration. The parameters like pH and accumulation time were optimized at 4 pH and 18 min, respectively, corresponding to the maximum inhibition ratio (ΔI/I0). The electrochemical sensor had a relative standard deviation (RSD) of up to 7.05 % (n = 3), which indicated reproducible results. The regression line showed linearity over a range of 25–200 parts per billion (ppb), and the limit of quantification (LOQ) was as low as 25 ppb (75.67 nM). The developed sensor was sensitive and selective, with a limit of detection (LOD) as low as 1 ppb (3.03 nM). The selectivity of the sensor was also studied by adding Pb(NO3)2, Zn(NO3)2, and NiCl2 to a solution of fixed malathion concentration, and minimal interference was observed. The sensor's functionality was validated using an unknown concentration of malathion with 96 % and 106 % recovery, respectively. The sensitivity of this proposed sensor was 0.0165 µA ppb⁻¹. Quantification of malathion was also facilitated using partial least squares (PLS) algorithms utilizing the sensory measurements of the malathion‐contaminated samples. PLS is a statistical machine learning algorithm that has been used here to develop a predictor for unknown malathion concentration using the DPV current signatures of the contaminated solution with a nominal error of 5.0 %.

Combined drying through convection and radiation allows for process intensification and thus for an increase in the drying rate as well as in the range of applications. Established combined drying models have mainly focused on drying thin layers of wet solids, not liquid droplets. In this work, the drying of pure solvent droplets as well as the drying of a polymer solution were studied. Experiments were performed to determine the influence of convective airflow temperature and radiative power on the mass reduction rate in the first phase of drying. A simplified model was developed for the combined drying of large solvent droplets and transferred to the polymer solution. The developed empirical model allowed for drying rate predictions with an accuracy similar to established convective drying models.

The characterization of a double salt synthesized from aqueous solutions of ammonium sulfate and magnesium sulfate is reported. Thermal analysis indicates that the resulting crystals incorporate six water molecules, yielding a compound with the composition (NH4)2Mg(SO4)2·6H2O. X‐ray diffraction confirms the structural stability of the crystals in both water and ethanol–water mixtures. Two key aspects were investigated, including the thermodynamics of the solid–liquid equilibrium (SLE) and the kinetics of primary nucleation. SLE measurements reveal that ethanol acts as an antisolvent. The dissolution process is endothermic, with the enthalpy of dissolution increasing with ethanol content. The enthalpy of dissolution in a solvent containing 10 % (w/w) of ethanol is +21.92 kJ mol⁻¹, compared to +17.14 kJ mol⁻¹ in water. Furthermore, the nucleation process follows second‐order kinetics, with the nucleation rate constant exhibiting a strong dependence on solvent composition.

The aim of this study is to perform process hazard analysis and safe process design for the prevention of process accidents in solid propellant mixers. Propellant mixers inherently entail a high level of risk due to the nature of the propellant production process. Processes carried out using propellant mixers pose significant risks when they lack a design that incorporates current technologies. Information related to chemicals, process equipment, and automation systems were compiled in PSI. Hazard and operability (HAZOP) and fault tree analysis (FTA) were performed to identify the potential hazards of the process and evaluate the probabilities. Sample facility maintenance data and values in databases were used for the process equipment's probability of failure on demand, and the TESEO method was used to quantify human errors. It was determined that the potential accident scenarios had similar failure probabilities. The use of automation was very important to eliminate the risks that threaten human life.

This work investigates the sulfonation behavior of styrene‐based resins crosslinked with divinylbenzene (DVB) and trimethylolpropane triacrylate (TMPTA) under varying conditions. TMPTA‐formulated resins initially exhibited lower ion exchange capacity (IEC) (∼1.13 mmol g⁻¹) than DVB‐crosslinked resins (∼2.94 mmol g⁻¹). However, optimized sulfonation conditions, including temperature and resin swelling, doubled the IEC of TMPTA‐based resins. Modeling indicated SO3H groups in both resins, with higher accuracy (R² = 0.9998) when using a sulfonic group molecular weight of 161 g mol⁻¹. Differences in reactivity and degradation rates (6 × 10⁻³ min⁻¹ for STY/DVB and 8 × 10⁻² min⁻¹ for STY/TMPTA) are also highlighted.

Direct electrochemical CO2 reduction as well as water electrolysis (WEL) combined with hydrogenation of CO2 to methanol (MeOH) and subsequent conversion to olefins are emerging as two possible pathways for sustainable olefin production. We provide an assessment of both routes such that they can be compared in terms of energy efficiency and projected costs. Through a sensitivity analysis, we identify bottlenecks and offer targets to achieve by catalysis design and engineers. At the current state, the electrocatalytic CO2 reduction has a much lower energy efficiency, requiring major improvements in the resulting overall cell potential and achieved faradaic efficiency. The MeOH route is mainly hampered by the overpotential required for WEL and the selectivity of olefin production, resulting in 50 kWh kg⁻¹ of olefin.

This study optimizes silver nanoparticle synthesis using response surface methodology to predict particle size diameter. Factors including agitation frequency, flow, temperature, reducing agent concentration, and heating time were varied using citrate and borohydride separately. Particle size was measured via dynamic light scattering and morphology analyzed by transmission electron microscope. Regardless of the reducing agent, concentration most significantly influenced particle size. Interactions were also crucial. Sodium borohydride synthesis yielded small, narrowly distributed nanoparticles across various size ranges. The study demonstrates the production of nanometric particles suitable for diverse technological applications.

To suppress thermal runaway during the synthesis process of tert‐butyl peroxybenzoate (TBHB), phase change microcapsules (microPCMs) were prepared using paraffin as the core material and melamine‐formaldehyde resin (MF) as the wall material via in situ polymerization. When the emulsification time was 20 min, the reaction temperature was 80 °C, and the paraffin mass was 10 g, the characterization of SEM, Fourier transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and x‐ray photoelectron spectroscopy (XPS) confirmed that the microPCMs were successfully fabricated, with microcapsule encapsulation rate reaching 62.5 %. The investigation into the thermal runaway suppression effect of microPCMs during the synthesis of TBPB revealed that adding 5 g of microPCMs at 50 °C optimized overtemperature suppression, reducing the maximum temperature of the reaction system from 58.3 °C to 50.3 °C. This work expands the application of microPCMs in semi‐batch reactions and has significant implications for the prevention of thermal runaway incidents.

Controlling multiple input–multiple output (MIMO) processes is challenging due to loop interactions. This study explores a modified fractional‐order PID (MFOPID) controller for a two‐input, two‐output mixing tank system. MFOPID design involves individual loop controllers based on the Nelder–Mead algorithm. Relative gain array analysis optimizes loop interactions, complemented by a simplified decoupler. Comparative evaluation against Ziegler–Nichols, internal model control, and standard FOPID controllers demonstrates a superior performance of MFOPID controller offering smoother signals and demonstrating significant improvement in various performance indices. These findings underscore the efficacy of the MFOPID controller in enhancing control performance in MIMO systems.

The performance of multiple coaxial hybrid impellers in a stirred bioreactor has been experimentally characterized. To accomplish this objective, tests have been performed concerning the growth of the bacterium Azotobacter vinelandii , alginate production, sucrose consumption, and viscosity. The bacterial synthesis of the exopolysaccharide alginate results in an augmented viscosity during cultivation, thereby influencing the oxygen transfer rate. Following a comparative analysis of the results obtained from the traditional Rushton turbines, it has been observed that implementing hybrid impellers yields enhanced biomass production, increased alginate output, and the generation of more viscous cultures. These findings are substantiated by the hydrodynamic data presented in a preceding study.

A sustainable porous carbon (WSPC) was applied to remove atrazine and 2,4‐ d (2,4‐dichlorophenoxyacetic acid) pesticides commonly used in cultivating grains and cereals. The 2,4‐ d and atrazine removals were favored at original pH values. The equilibrium occurred according to Brouers–Sotolongo's description. The thermodynamic studies supported the exothermic behavior. The adsorption data over time were represented by the pore‐volume and surface diffusion model. Statistical mechanics revealed that the multilayer model showed the best fit for the adsorption isotherms. The steric parameters indicated that the adsorbed molecules are perpendicular to the WSPC surface. The number of adsorbed molecules decreased with increasing temperature for 2,4‐ d , whereas for atrazine, it remained constant. The adsorption energy indicates that the process is governed by physisorption. WSPC efficiently removed atrazine and 2,4‐ d from real river waters, reaching 98 % and 92 % removal percentages, respectively.

To reveal the flow behavior of microcrystalline cellulose (MCC) powders in a pyramidal silo with an inclined bottom, experiments are performed along with the discrete element method (DEM) simulations to study the discharge process. In mixtures, the mass flow rate (MFR) of MCC powders increases when the percentage of the fine increases. Using the same outlet size, the smaller valley angle of a pyramidal silo results in faster flow rates. From this DEM study, it is observed that particle segregation takes place for mixtures comprising varying particle sizes in a pyramidal silo. The effect of segregation is more when the mixture contains fewer fines. The valley angle of the silo is inversely proportional to the intensity of particle segregation. The intensity of segregation computed by DEM is higher in the case of binary mixtures compared to the ternary mixtures. The segregation can be reduced by increasing the fine mass fraction in a mixture and reducing the particle size difference.

The study explores removal of hexavalent chromium (Cr(VI)) from wastewater using magnetic biochar (MB) from Ziziphus jujube seeds (ZJS). Modified biochar was characterized for functional groups, crystalline structure, morphological characteristics , surface area, elemental content, and magnetic properties. Batch experiments were conducted considering pH, initial chromium, adsorbent dosage, and contact time as controlling factors. The study demonstrates MB, with its high carboniza-tion and magnetic saturation, effectively removes 98 % of hexavalent chromium from aqueous solutions. Langmuir and pseudo-second-order models were best fit models for adsorption, and 0.3 M HCl recovered more than 95 % of Cr(VI) than other concentrations.