Understanding the Liberation of Asphaltenes on the Muscovite Surface

Separation of heavy hydrocarbons from mineral surfaces is the key step for unconventional oil production and remediation of oil-contaminated soils. The presence of asphaltene and the coexistence of mineral rocks are considered as the most challenge during the above separation processes. Herein, the liberation of asphaltenes (and/or heavy oil) on the muscovite [KAl₂(Si₃Al)­O₁₀(OH)₂)] surface has been systematically investigated through instrumental characterization and molecular dynamics (MD) simulation. It is observed that, quite different from that on the silica surface, asphaltenes can flake off from the muscovite surface as a result of the weaker adhesion force between asphaltenes and the muscovite surface. This liberation pattern was also found to be influenced by the addition of other oil fractions. The micro force measurements by atomic force microscopy show that the adhesion force between asphaltenes and muscovite is weaker than that between asphaltenes and silica in both air and water. Assisted by the MD simulation, it is found that the detachment of asphaltenes is highly dependent upon the mineral types and the presence of the water film on the mineral surfaces. Although the van der Waals force is found to be the main force between asphaltenes and mineral surfaces, the presence of potassium ions (K⁺) on the muscovite surface could increase the percentage of the electrostatic forces in the total force. Furthermore, the presence of a 0.4 nm water layer (in the air) between asphaltenes and the muscovite surface could reduce their interactions dramatically compared to that in a vacuum state. This finding suggests that the presence of water between the mineral surface and oil is beneficial for the separation of oil from the mineral surface. In addition, the asphaltene molecules are found to contact with the silica surface by face-to-face (aromatic ring) form, while a much more perpendicular orientation of the asphaltene molecules on the muscovite surface

Quick Decision-Making for Close-Boiling Distillation Schemes

Separating close-boiling components using distillation is very common in industry. Considering the higher capital and energy intensity of the task, schematic selection of optimal distillation strategies becomes a significant decision of both industrial and methodological importance. In this sense, this paper introduces a reliable shortcut method of simplicity and robustness for optimizing the target of total annualized cost (TAC). In detail, selective analyses are carried out among four schematic candidates for three close-boiling systems. The schemes are conventional distillation column, mechanical vapor recompression (MVR), double-effect distillation, and distillation with a recycle process. The mixtures to be separated are methyltrichlorosilane/dimethylchlorosilane, methylcyclopentane/cyclohexane, and isobutanol/<i>n</i>-butanol. After the first round evaluation, hydraulic calculations through rigorous simulations are worked out to size the equipment, which is necessary for TAC analyses. In the second round comparison, MVR stands out to be a more attractive option for close-boiling separations than other configurations

Distribution of Saturates, Aromatics, Resins, and Asphaltenes Fractions in the Bituminous Layer of Athabasca Oil Sands

The composition and distribution of saturates, aromatics, resins, and asphaltenes (SARA) fractions in the bituminous layer on the surface of Athabasca oil sands were identified using elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (SEM) with an energy-dispersive spectrometer (EDS), and Fourier transform infrared spectrometry (FTIR). The contents of elements sulfur (S) and nitrogen (N) and the ratios of carbon/sulfur (C/S) and carbon/nitrogen (C/N) were characterized as potential indicators for evaluating the distribution of SARA fractions in the bituminous layer. Results indicated that saturates and aromatics tend to deposit at the outer bituminous layer, while asphaltenes and resins were inclined to distribute at the inner layer. Results also suggested that the distribution of SARA fractions was thermodynamically dependent and susceptible to thermal treatment. On the basis of the experimental results, a conceptual distribution model was proposed, which is supposed to serve as a basis for future studies on the liberation of bitumen from oil sands and the operation conditions for oil sands processing

Means, standard deviations (SD) and correlations of continuous variables.

<p>**. Correlation is significant at the 0.01 level (2-tailed).</p><p>Means, standard deviations (SD) and correlations of continuous variables.</p

Age, marital status, education level characteristic and means and standard deviations of variables.

<p>Age, marital status, education level characteristic and means and standard deviations of variables.</p

Correlations between age, avoidant coping, approach coping, self-esteem and problematic drinking among females.

<p>^a P<0.01</p><p>Correlations between age, avoidant coping, approach coping, self-esteem and problematic drinking among females.</p

Correlations between age, negative coping, positive coping, self-esteem and problematic drinking among males.

<p>^a P<0.01</p><p>Correlations between age, negative coping, positive coping, self-esteem and problematic drinking among males.</p

Predictor variables among males and females in China.

<p>Predictor variables among males and females in China.</p

Regression analysis results, with problematic drinking as outcome and negative coping and positive coping as mediators among males.

<p>^a associations of self-esteem with problematic drinking</p><p>^b associations of self-esteem with negative coping/ positive coping</p><p>^c associations between negative coping/ positive coping and problematic drinking after controlling for the predictor variables [Age, marital status, educational levels and household income]</p><p>^d associations of self-esteem with problematic drinking after adding negative coping/ positive coping as mediator</p><p>^e the product of a and b;</p><p>^f the bias-corrected and accelerated 95% confidence interval;</p><p>^g p<0.01</p><p>Regression analysis results, with problematic drinking as outcome and negative coping and positive coping as mediators among males.</p

GNB3 and CREB1 gene polymorphisms combined with negative life events increase susceptibility to major depression in a Chinese Han population

<div><p>Background</p><p>Major depression (MD) is caused by a combination of genetic and environmental factors. In this study we investigated the interaction of variations in the G-protein beta 3 subunit (GNB3) and cAMP response element binding protein 1 (CREB1) genes with negative life events in the pathogenesis of MD. One GNB3 polymorphism (rs5443) and four CREB1 polymorphisms (rs2253206, rs2551941, rs6740584, rs11904814) were investigated based on known associations with MD.</p><p>Methods</p><p>512 patients with MD and 513 control subjects were genotyped. The frequency and severity of negative life events were measured by the Life Events Scale (LES). Gene-environment interactions (G×E) were assessed using the generalized multifactor dimensionality reduction (GMDR) method.</p><p>Results</p><p>Differences in GNB3 rs5443 allele frequencies and genotype distributions were observed between MD patients and controls. Significant G×E interactions were detected between negative life events and genotypic variation of all five single nucleotide polymorphisms (SNPs). Individuals carrying the T^- allele of rs5443 (CC), A^- allele of rs2253206 (GG), T^- allele of rs2551941 (AA), C^- allele of rs6740584 (TT) or G^- allele of rs11904814 (TT) conferred susceptibility to MD in subjects only exposed to high-negative life events. However, individuals with the T⁺ allele of rs5443 (CT, TT) were susceptible to MD when exposed to low negative life events.</p><p>Conclusions</p><p>Interactions between GNB3, CREB1 and negative life events were revealed. Further evidence is provided about the role of the environment in genetic vulnerability to MD.</p></div