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The precipitation and deposition of asphaltenes are significant challenges in the petroleum industry resulting in substantial costs. A practical approach to addressing this issue is to use chemicals as inhabiting and dispersing agents. Zwitterionic surfactants are interesting materials in this field. In this study, three zwitterionic compounds including 2-(1-methyl-1H-imidazol-3-ium-3-yl)butane-1-sulfonate (MIBS), 4-(pyridin-1-ium-1-yl) butane-1-sulfonate (PBS), and 4-(tributylammonio)butane-1-sulfonate (TBBS) were synthesized and characterized by FT-IR, NMR spectroscopy, thermogravimetric, and differential thermal analysis. The ability of these zwitterions to prevent asphaltenes precipitation was investigated using interfacial measurements, ultraviolet spectroscopy, quartz microbalance analysis, particle size analysis, and optical microscopy. The results showed that the MIBS zwitterion, which contains an imidazole cation, was the most effective in dispersing asphaltene aggregates compared to the other two zwitterions. For instance, the UV spectroscopy results showed that the dispersion indexes for MIBS, PBS, and TBBS were 52.8%, 29.9%, and 16.3%, respectively. In addition, the size of asphaltene particles reached from 2179 nm to 622, 1489, and 2038 nm for MIBS, PBS, and TBBS, respectively. Finally, a comparison between the performance of these zwitterions with sodium dodecyl sulfonate (SDS) and tetrabutylammonium hydrogen sulfate (TBAHS) showed the following trend: MIBS (90.5%)> PBS (79.4%) > TBAHS (75%)> SDS (73.9%) >TBBS (46%). [ABSTRACT FROM AUTHOR]

Eshnan (Seidlitzia rosmarinus Bunge ex Boiss), a salt-tolerant and drought-resistant plant, is often found in salty desert areas. In the present report, Eshnan was subjected to extraction using methanol, ethanol, and water utilizing a Soxhlet extractor. A total of 51 compounds were identified in the plant inclusive of secondary metabolites such as phenols, polyphenols, phytosterol, amino acid, fatty acid, etc. utilizing GC/MS analysis. The methanolic extract had the highest phenolic content, whereas ethanolic extract had the highest antioxidant activity. Aqueous extract contained the highest levels of saponin, as well. CTAB represented a higher foaming capacity as compared to the plant extracts. HPLC analysis of the plant extract confirmed the presence of the saponin ginsenoside Rb1 for the first time. The results showed a rich source of saponins, polyphenols, and fatty acids in Eshnan. Due to the significant quantity of saponins within the plant, it can be used as an alternative natural surfactant to chemical surfactants that are currently utilized in industry. [ABSTRACT FROM AUTHOR]

• Application of ten Tetraalkylammonium and phosphonium salt were evaluated as asphaltenes and dispersant. • The systematic study using UV–vis spectroscopy was done to investigate interactions between asphaltenes and organic salts based on the size and the shape of the cations and anions. • The length of alkyl chain in cations and hydrophobicity of anion have crucial role in preventing of asphaltene stacking interactions. • This mechanistic study was revealed that the role of anions on the stability of asphaltene aggregates is more important than cations. Asphaltenes deposition is one of the most severe problems in the petroleum industry, imposing high costs on oil producer companies. The use of chemical dispersants reduces the risk of asphaltene deposition. For this purpose, a variety of chemicals with different structures and functional groups were designed and synthesized. Organic quaternary salts, such as ionic liquids, have been widely used to control asphaltene deposition over the last two decades, but the mechanism of their interaction with asphaltene has not been studied in detail. In this study, the interaction of ten commercial quaternary ammonium and phosphonium salts with asphaltene molecules was investigated using ultraviolet-visible (UV-Vis) spectroscopy. It was observed that the size, shape, and hydrophobicity of their cations or anions play an essential role in the dispersion of asphaltene aggregations. The results showed that the interaction of these quaternary salts is strongly influenced by the hydrophobic nature of the salt, and salts with more hydrophobic cations and anions, such as tetrabutylammonium iodide, tetrabutylammonium hexafluorophosphate, and cetyltrimethylammonium bromide, can better disperse asphaltene aggregations. The results also revealed that the role of anions such as iodide, and hexafluorophosphate in the dispersion of asphaltene aggregates is more important than cations. In addition, the results showed that except for tetramethylammonium bromide, the efficiency of the salts was increased with increasing concentration. [ABSTRACT FROM AUTHOR]

In this research, a novel Resonance Rayleigh Scattering (RRS) aptasensor was developed for thrombin monitoring using in-situ synthesized and embedded Au nanoparticles (AuNPs) into poly vinyl alcohol –borax hydrogel (PBH). Thiolated-thrombin binding aptamer (thiolated-TBA) was attached to the surface of AuNPs embedded into PBH to design the PBH-aptasensor for thrombin detection (thiolated-TBA@AuNPs–PBH). To verify the characteristic and morphology of PBH nanocomposite, energy dispersive X-ray analysis, TEM, average particle size analizer and UV–Vis spectra were performed. The difference in RRS intensities in the absence and presence of thrombin was calculated and selected as the monitoring signal. Effect of different parameters on the RRS signal was investigated at excitation wavelength of 500 nm. Under the approved conditions, the linear detection range was validated over the concentration of 0.70 pM- 0.02 μM. The limit of detection based on 3S b was 0.10 pM. The relative standard deviation for 5.6 pM and 3.6 nM were 4.0 and 2.7% (n = 10), respectively. The proposed aptasensor was successfully applied as an experimental model for thrombin detection in serum samples of healthy volunteers with acceptable results. Image 1 • A new Resonance Rayleigh Scattering aptasensor has been designed for thrombin detection. • Au nanoparticles (AuNPs) were in situ synthesized into poly vinyl alcohol –borax hydrogel for the first time. • Thiolated-thrombin binding aptamer (thiolated-TBA) was attached to the surface of AuNPs. • The bio-sensing platform is selective and sensitive for thrombin detection. [ABSTRACT FROM AUTHOR]

Abstract: We have developed a reliable, fast, and highly sensitive analytical method utilizing dispersive liquid–liquid microextraction and gold nanoparticles probes for ziram (zinc bis(dimethyldithiocarbamate)) determination. The method is based on the in situ formation of gold nanoparticles in carbon tetrachloride as an organic phase. It was found that the trace levels of ziram influenced the formation of gold nanoparticles, leading to absorbance change of a sedimented phase. The results of the colorimetric ziram determination were in the concentration range of 0.12–2.52 ng/mL with a limit of detection of 0.06 ng/mL. The formation of the stable and dispersed gold nanoparticles in the organic phase provides a good precision for dispersive liquid–liquid microextraction method, resulting in the relative standard deviation of 3.8 and 1.2% for 0.56 and 1.58 ng/mL of ziram, respectively. This method has been successfully used for the ziram determination in samples of well and river water, soil, potato, carrot, wheat, and paddy soil. [ABSTRACT FROM AUTHOR]

In this study, chitosan-SnO2 nanoparticles biocomposite was synthesized and investigated as an efficient green biosorbent for adsorption of Fe(II) ions. The as-prepared bio-nanocomposite was characterized by Fourier-transform infrared spectroscopy, X-ray powder diffraction spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Furthermore, a dispersive micro-solid phase extraction (D-μ-SPE) based on microvolume spectrophotometric detection technique was developed for preconcentration as well as determination of Fe(II) ions in environmental and wastewater samples. After reduction of Fe(III) ions by the addition of hydroxylamine hydrochloride as reducing agent, the system was applied to the total iron. Different parameters influencing the extraction efficiency including sample pH, the amount of adsorbent, adsorption time, and properties of desorption solvent were optimized. The adsorption isotherms of the synthesized adsorbent were also studied. The adsorption isotherm was well described by the Freundlich model and showed good adsorption capacity for the Fe(II) ions (17.24 mg g–1). The calibration graph was linear in the range 10–1,200 ng mL–1 of Fe(II) and total iron. The detection limit of the method for determination of Fe(II) was 2.8 ng mL–1 with a relative standard deviation of less than 1.3%. The adsorption capacity of the regenerated adsorbents was maintained at 90% even after the fourth adsorption–desorption cycle. [ABSTRACT FROM AUTHOR]

Zirconia nanoparticles were modified by sodium dodecyl sulfate (SDS) under ultrasonic action and used as a new adsorbent for the removal of brilliant cresyl blue dye from aqueous solutions. The effect of different parameters such as pH, salt concentration, and amount of adsorbent on the removal procedure was studied and optimum conditions were established. The adsorption data were fitted to Langmuir, Freundlich, and Temkin isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model. The kinetic studies indicated that the experimental data were fitted well by the pseudo-second-order model. The maximum adsorption capacity was found to be 34.4 mg g−1of adsorbent for brilliant cresyl blue. The removal procedure was applied to the removal of brilliant cresyl blue form water samples. [ABSTRACT FROM AUTHOR]