Study on the kinetics of formation process of emulsion of heavy oil and its functional group components.

Enhanced oil recovery (EOR) by in situ formation of oil-in-water emulsion in heavy oil cold production technology has received growing interest from the petroleum industry. We present an experimental study of emulsification of model oils prepared by heavy oil and its functional group compositions dissolved into toluene brought into contact with a surfactant solution. The effects of functional group composition, emulsifier concentration, temperature, pH and stirring speed on the emulsification rate of heavy oil was investigated. A second-order kinetic model characterizing the temporal variation of conductivity during the emulsification has been established. The results show that acidic and amphoteric fractions exhibit higher interfacial activity, larger emulsification rate constant and faster emulsification rate. With the increase of emulsifier concentration, the emulsification rate constant increase to the maximum value at a concentration of 0.05 mol/L before decreasing. Temperature increase benefits the emulsification rate and the activation energy of the emulsification process is 40.28 kJ/mol. Higher pH and stirring speed indicate faster emulsification rate. The heterogeneity of emulsions limits the accuracy of dynamic characterization of the emulsification process and the determination method of emulsification rate has always been controversial. The conductivity method we proposed can effectively evaluates the emulsification kinetics. This paper provides theoretical guidance for an in-depth understanding of the mechanism and application of cold recovery technology for heavy oil.

Enhanced photocatalytic ammonia oxidation over WO3@TiO2 heterostructures by constructing an interfacial electric field.

WO3 nanorods and xWO3@TiO2 (WO3/TiO2 mass ratio (x) = 1-5) photocatalysts were synthesized using the hydrothermal and sol-gel methods, respectively. The photocatalytic activities of xWO3@TiO2 for NH3 oxidation first increased and then decreased with a rise in TiO2 content. Among them, the heterostructured 3WO3@TiO2 photocatalyst showed the highest NH3 conversion (58 %) under the simulated sunlight irradiation, which was about two times higher than those of WO3 and TiO2. Furthermore, the smallest amounts of by-products (i.e., NO and NO2) were produced over 3WO3@TiO2. The enhancement in photocatalytic performance (i.e., NH3 conversion and N2 selectivity) of 3WO3@TiO2 was mainly attributed to the formed interfacial electric field between WO3 and TiO2, which promoted efficient separation and transfer of photogenerated charge carriers. Based on the results of reactive species trapping and active radical detection, photocatalytic oxidation of NH3 over 3WO3@TiO2 was governed by the photogenerated holes and superoxide radicals. This work combines two strategies of morphological regulation and interfacial electric field construction to simultaneously improve light utilization and photogenerated charge separation efficiency, which promotes the development of full-spectrum photocatalysts for the removal of ammonia.

[Association between very low density lipoprotein cholesterol and cholesterol absorption/synthesis markers in patients with moderate and high risk of coronary heart disease].

OBJECTIVE: To evaluate the association between very low density lipoprotein cholesterol (VLDL-C) and cholesterol absorption and synthesis markers in patients with moderate and high risk of coronary heart disease. METHODS: A total 363 statin-naïve patients with moderate and high risk of coronary heart disease were consecutively recruited from two hospitals in Shanxi and Henan provinces between October 2008 and June 2009. A standard questionnaire and physical examination were performed at baseline. Atorvastatin (20 mg/day) was administered to patients for 4 weeks. Venous blood samples after an overnight fast were collected before and after treatment for measuring VLDL-C and cholesterol absorption and synthesis markers. In qualitative analyses, the baseline level of cholesterol absorption and synthesis markers and their reduction after atorvastatin treatment were categorized into 3 tertile groups. RESULTS: (1) Of 363 patients, 283 patients with mean age of (55.43±9.01)years old with complete data were finally analyzed. The median level of baseline VLDL-C was 1.06 (0.65, 1.86) mmol/L. The median level of baseline cholesterol absorption marker (Campesterol) and cholesterol synthesis marker (Lathosterol) was 6.01 (3.78, 9.45) mg/L and 13.46 (8.30, 21.07) mg/L, respectively. (2) Partial correlation analysis and multiple regression showed the baseline level of VLDL-C was positively correlated with Campesterol (r=0.153, P<0.05) but not with Lathosterol(r=0.182, P=0.173). Furthermore, baseline VLDL-C level significantly increased with tertile of the baseline level of Campesterol in the qualitative analyses(P for trend=0.035). (3) Mean reduction in VLDL-C levels was 38.0% after 4 weeks atorvastatin treatment. VLDL-C reduction was positively correlated with Campesterol reduction (r=0.331, P<0.001). VLDL-C reduction significantly increased with the tertile of Campesterol reduction (P for trend=0.032). But this trend was not observed between VLDL-C level and Lathosterol (P for trend=0.798). CONCLUSION: The level of VLDL-C was closely related to cholesterol absorption marker, and further studies are needed to validate if inhibitor of cholesterol absorption (for example by Ezetimibe) could bring about more effective VLDL-C lowering effect in this patient cohort.