• Energy Research

The feasibility study of utilizing sunflower oil as renewable biomass source to develop highly effective inhibitors for mild steel corrosion (MS) in the 15% HCl medium was done by weight loss, potentiodynamic polarization (PDP), dynamic electrochemical impedance spectroscopy (DEIS), and electrochemical impedance spectroscopy (EIS), supported with energy-dispersive X-ray (EDX), atomic force microscopy (AFM), and field-emission scanning electron microscope (FESEM) techniques. Moreover, a complementary theoretical investigation was carried out to clarify the inhibition mechanism of inhibitors by density functional theory (DFT), density functional based tight-binding (DFTB), and molecular dynamics (MD) simulation approaches. The obtained results confirm that sunflower-oil-based corrosion inhibitor (SFOCI) has a significant anticorrosion property toward the dissolution of MS in 15% HCl solution in the temperature range 20-80 °C. In addition, the results show that SFOCI could provide an inhibition efficiency of 98 and 93% at 60 and 80 °C, respectively. The inhibition mechanism of SFOCIs was mixed-type and their adsorption on the surface of MS was mainly chemisorption. The FESEM and EDX studies proved the presence of SFOCI molecules on the surface of MS. In addition, the adsorption energy of SFOCI indicated an intense interaction between the inhibitor and surface of Fe. The results of this study could open a new window for the design and development of scalable and effective eco-friendly vegetable-oil-based corrosion inhibitors for highly corrosive solutions at high temperatures.

The development of efficient, non-foaming promoters is essential for advancing the industrial applications of solidified gas hydrates in carbon capture, natural gas storage, and transportation. In this study, a novel surfactant, containing sulfonate, amide, and carboxyl groups (SSAC), was introduced as a promoter for methane hydrate formation. SSAC was synthesized by integrating the chemistries of amino acids and sodium dodecyl sulfate (SDS), distinguishing it from existing promoters. High-pressure autoclave experiments demonstrated that SSAC significantly enhanced the kinetics of methane hydrate formation, at a low concentration of 5 ppm, achieving a maximum water-to-hydrate conversion of 85.2 %, equivalent to a storage capacity of 163.5 v/v in deionized water. Increasing the SSAC concentration to 500 ppm resulted in an impressive conversion rate of 94.6 % and a storage capacity of 181.6 v/v. Methane recovery was accomplished without foaming within 15 min during hydrate dissociation at room temperature, addressing a critical challenge in current hydrate-based storage systems. Molecular dynamics simulations further revealed that SSAC molecules act as collectors for methane molecules in solution, thereby enhancing the rate of hydrate growth and increasing the number of hydrate cavities. Notably, SSAC exhibited a biodegradation level of 41 % after 28 days, indicating its potential for natural degradation and environmental compatibility. This combination of low concentration efficiency, foam-free formation, environmental sustainability, and enhanced methane collection is unprecedented in the current literature, highlighting the innovative nature of this work. These findings suggest that the integration of amino acid structures with anionic surfactants offers a promising strategy for designing effective promoters, with significant implications for energy storage, seawater desalination, and carbon capture technologies.

Abstract The continuously increasing demand for natural gas as an available and clean energy source indicates an inevitable transition to develop more promising technologies such as solidified natural gas (SNG) storage. Herein, we present a comprehensive experimental and computational study of the utilization of sunflower oil as a renewable biomass source to design highly efficient promoters based on the properties of sodium dodecyl sulfate (SDS) for methane hydrate formation. The effect of sunflower oil-based promoters (SFOPs) on methane hydrate kinetics was investigated theoretically via molecular dynamics (MD) simulation and experimentally under both dynamic (stirred reactor) and static (in the presence of porous media) conditions. SFOP1 considerably reduced induction time and overall time of the hydrate formation process compared to SDS under both conditions. In addition, SFOP1 significantly enhanced the kinetic constant of hydrate formation by 13.5 times, 3.7 times, and 2.5 times compared to pure water, SFOP2, and SDS systems, respectively, (in dynamic conditions). Moreover, both SFOPs improved the number of moles of gas consumed up to 450 mM in dynamic and 200 mM in static conditions compared to the pure water test. In contrast to the SDS solution, no foam formation was observed in the solution containing SFOPs. The MD results revealed that the SFOPs increased the transfer of methane molecules to the growing hydrate surface, which lead to enhance the kinetics of methane hydrate formation. Besides, more hydrate was formed by the addition of SFOP1 because of the improvement in the hydrogen bonds between water-water molecules in comparison with SFOP2. These findings clearly confirm that sunflower oil can be used for the development of green and more efficient promoters than SDS for methane hydrate formation without foam generation during the process.