Effects of Ionic Liquid, 1-Ethyl-3-methylimidazolium Chloride ([EMIM]Cl), on the Material and Electrical Characteristics of Asphaltene Thin Films

Lignosulfonate-Based Ionic Liquids as Asphaltene Dispersants

Asphaltenes are recognized as being troublesome from upstream to downstream in the oil industry due to their tendency to precipitate and self-associate. Their extraction from asphaltenic crude oil for a cost-effective refining process is a crucial and critical challenge in the oil and gas sector. Lignosulfonate (LS), as a by-product of the wood pulping process in the papermaking industry, is a highly available and underutilized feedstock. This study aimed to synthesize novel LS-based ionic liquids (ILs) by reacting lignosulfonate acid sodium salt [Na]₂[LS] with different alkyl chains of piperidinium chloride for asphaltene dispersion. The synthesized ILs, 1-hexyl-1-methyl-piperidinium lignosulfonate [C₆C₁Pip]₂[LS], 1-octyl-1-methyl-piperidinium lignosulfonate [C₈C₁Pip]₂[LS], 1-dodecyl-1-methyl-piperidinium lignosulfonate [C₁₂C₁Pip]₂[LS] and 1-hexadecyl-1-methyl-piperidinium lignosulfonate [C₁₆C₁Pip]₂[LS] were characterized using FTIR-ATR and ¹H NMR for functional groups and structural confirmation. The ILs depicted high thermal stability because of the presence of a long side alkyl chain and piperidinium cation following thermogravimetric analysis (TGA). Asphaltene dispersion indices (%) of ILs were tested by varying contact time, temperature and ILs concentration. The obtained indices were high for all ILs, with a dispersion index of more than 91.2% [C₁₆C₁Pip]₂[LS], representing the highest dispersion at 50,000 ppm. It was able to lower asphaltene particle size diameter from 51 nm to 11 nm. The kinetic data of [C₁₆C₁Pip]₂[LS] were consistent with the pseudo-second-order kinetic model. The dispersion index (%), asphaltene particle growth and the kinetic model agreed with the molecular modeling studies of the HOMO-LUMO energy of IL holds.

Biological denitrification potential of cellulase-producing Cupriavidus sp. ZY7 and denitrifying Aquabacterium sp. XL4 at low carbon-to-nitrogen ratio: Performance and synergistic properties

This study emphasizes on the cellulase production characteristics of strain ZY7 and its collaboration with nitrate-dependent ferrous oxidizing (NFO) strain XL4 to achieve efficient denitrification at low carbon-to-nitrogen (C/N) ratio. Results indicated that the denitrification efficiency increased from 65.47 to 97.99% at 24 h after co-culture at C/N of 1.0. Three-dimensional fluorescence excitation-emission matrix (3D-EEM) showed significant changes in the intensity of soluble microbial products (SMP), fulvic-like materials, and aromatic proteins after co-culture. Bio-precipitates were characterized by Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), and X-ray diffraction (XRD), which showed that cellulose structure was disrupted and the metabolites were potential carbon source for denitrification. In addition, cellulase activity suggested that the hydrolysis of β-1,4-glycosidic bonds and oligosaccharides may be the rate-limiting steps in cellulose degradation. This work promoted the understanding of denitrification characteristics of co-culture and expanded the application of cellulose degrading bacteria in sewage treatment.

Laboratory Experiments on the In Situ Upgrading of Heavy Crude Oil Using Catalytic Aquathermolysis by Acidic Ionic Liquid

Heavy and extra heavy oil exploitation has attracted attention in the last few years because of the decline in the production of conventional crude oil. The high viscosity of heavy crude oil is the main challenge that obstructs its extraction. Consequently, catalytic aquathermolysis may be an effective solution to upgrade heavy crude oil to decrease its viscosity in reservoir conditions. In this regard, a series of acidic ionic liquids, 1-butyl-1H-imidazol-3-ium 4-dodecylbenzenesulfonate (IL-4), 1-decyl-1H-imidazol-3-ium 4-dodecylbenzenesulfonate (IL-10), and 1-hexadecyl-1H-imidazol-3-ium 4-dodecylbenzenesulfonate (IL-16), were utilized in the aquathermolysis of heavy crude oil. Of each IL, 0.09 wt % reduced the viscosity of the crude oil by 89%, 93.7%, and 94.3%, respectively, after the addition of 30% water at 175 °C. ILs with alkyl chains equal to 10 carbon atoms or more displayed greater activity in viscosity reduction than that of ILs with alkyl chains lower than 10 carbon atoms. The molecular weight and asphaltene content of the crude oil were decreased after catalytic aquathermolysis. The compositional analysis of the crude oil before and after catalytic aquathermolysis showed that the molar percentage of lighter molecules from tridecanes to isosanes was increased by 26-45%, while heavier molecules such as heptatriacontanes, octatriacontanes, nonatriacontanes, and tetracontanes disappeared. The rheological behavior of the crude oil before and after the catalytic aquathermolytic process was studied, and the viscosity of the crude oil sample was reduced strongly from 678, 29.7, and 23.4 cp to 71.8, 16.9, and 2.7 cp at 25, 50, and 75 °C, respectively. The used ILs upgraded the heavy crude oil at a relatively low temperature.