Hydrodesulfurization (HDS) has been commercially employed for the production of ultra-low sulfur fuel oil. However, HDS is unable to remove sterically hindered sulfur-containing compounds such as dibenzothiophene (DBT) and benzothiophene (BT). An alternative way to remove sulfur is via extractive desulfurization system (EDS) using deep eutectic solvents (DES) as sustainable extractant. In this work, liquid polymer DES was synthesized using tetrabutylammonium chloride (TBAC) and poly(ethylene glycol) 400 (PEG) with different molar ratios. Response surface methodology (RSM) was applied to study the effect of independent variables toward extraction efficiency (EE). Three significant operating parameters, temperature (25–70 °C), DES molar ratio (1–3), and DES volume ratio (0.2–2.0), were varied to study the EE of sulfur from model oil. A quadratic model was selected based on the fit summary test, revealing that the extraction efficiency was greatly influenced by the amount of DES used, followed by the extraction temperature and PEG ratio. Although molar ratio of DES was less sensitive towards EDS performance, the EE was much higher at lower PEG ratio. For the realization of an energy-efficient EDS system, optimization of EDS parameters and EE was carried out via a desirability tool. At 25 °C, 1:1 molar ratio of TBAC to PEG, and DES-to-model-oil-volume ratio of 1, removal of DBT reached as high as 79.01%. The present findings could provide valuable insight into the development of practicable EDS technology as a substitute to previous HDS process.

In most carbon dioxide (CO₂) capture processes, chemical absorption using an amine solvent is widely used technology; however, the solvent is prone to solvent degradation and solvent loss which leads to the formation of corrosion. This paper investigates the adsorption performance of amine-infused hydrogels (AIFHs) to increase carbon dioxide (CO₂) capture by leveraging the potency of amine absorption and adsorption properties of class F fly ash (FA). The solution polymerization method was used to synthesize the FA-grafted acrylic acid/acrylamide hydrogel (FA-AAc/AAm), which was then immersed in monoethanolamine (MEA) to form amine infused hydrogels (AIHs). The prepared FA-AAc/AAm showed dense matrices morphology with no obvious pore at the dry state but capable of capturing up to 0.71 mol/g CO₂ at 0.5 wt% FA content, 2 bar pressure, 30 °C reaction temperature, 60 L/min flow rate, and 30 wt% MEA contents. Cumulative adsorption capacity was calculated and Pseudo-first order kinetic model was used to investigate the CO₂ adsorption kinetic at different parameters. Remarkably, this FA-AAc/AAm hydrogel is also capable of absorbing liquid activator that was 1000% more than its original weight. FA-AAc/AAm can be used as an alternative AIHs that employ FA waste to capture CO₂ and minimize the GHG impact on the environment.

Amine solvent has shown great sour gases separation capacity from natural gas. This paper studied the optimization of monoethanolamine loading capacity on the fly ash grafted polyacrylic acid hydrogel using response surface methodology. The central composite design was used to determine the effect of three independent variables particularly fly ash as a filler, N, N”-methylene bis acrylamide as a crosslinker, and ammonia peroxide sulphate as an initiator. The optimization study revealed the significance of factors in the following order: cross-linker > fly ash > initiator, with an R² value of 0.99. The fly ash grafted hydrogel achieved a maximum amine loading of up to 1550 wt.% with the addition of 1.1 g of fly ash, 0.07 g of cross-linker, and 0.07 g of initiator. It was investigated that varying the concentration of crosslinker was significantly enhanced the amine loading. Furthermore, SEM and FTIR were performed to analyze the morphology and chemical changes in the optimum fly ash grafted hydrogel. The results depicted that the fly ash grafted hydrogel has porous structure and ample space for amine uptake inside the pores. The fly ash-grafted hydrogel exhibits significant potential for efficient gas separation from natural gas. Its enhanced porosity, hydrophilicity, and capacity to incorporate functional groups, such as amines, enable the selective adsorption of impurities.

The safe and efficient removal of hydrogen sulfide (H₂S) from natural gas is essential to prevent environmental hazards and equipment corrosion. This study investigates the influence of crosslinker concentration on the H₂S adsorption performance of tetraethylenepentamine (TEPA) impregnated polyacrylic acid (PAA) hydrogels through a combination of experimental analysis and molecular dynamics (MD) simulations. The synthesized hydrogel samples were experimentally characterized using Fourier-Transform Infrared Spectroscopy (FTIR) to identify the functional groups. MD simulations were performed to optimize and equilibrate the molecular structures. Simulated X-ray diffraction (XRD) patterns were generated to analyze the structural characteristics of the models. Grand Canonical Monte Carlo (GCMC) simulations were used to investigate H₂S adsorption under different temperatures and pressures. The results reveal that increasing the crosslinker concentration reduces the hydrogel’s H₂S adsorption capacity (down to 1.5 mmol/g) by limiting available adsorption sites, restricting swelling, and negatively affecting TEPA distribution. Conversely, lower crosslinker concentrations enhance H₂S uptake (up to 3 mmol/g) by promoting polymer chain flexibility and enabling more effective TEPA–H₂S interactions. This integrated experimental and simulation study provides insight into the adsorption mechanisms of H₂S, offering valuable guidance for the development of high-performance amine-impregnated polymer hydrogels for industrial gas purification applications.