Electrochemical degradation of petroleum hydrocarbons (PAHS) from synthetic aqueous solutions

Water separated from crude oil and wastewater discharge from petroleum oil refineries contains significant quantity of dissolved hydrocarbons. Polycyclic aromatic hydrocarbons (PAHs) are major toxicants in wastewater of refineries. It is difficult to treat wastewater containing PAHs due to their recalcitrant property and low solubility. Conventional techniques for the treatment of wastewater are still a concern of toxicity. Electrochemical oxidation process has been found to be a favorable for treating wastewater. Electrodes with high stability and electrocatalytic activity are important factors for a successful electrochemical oxidation of toxic organics in wastewater. In this study titanium anodes were coated with tin, antimony and iridium oxide mixture from their respective salts by thermal decomposition method. FESEM and XRD used for surface characterization of Ti/SnO₂–Sb₂O₅–IrO₂ anode. Quantification of PAHs was done using GC–MS. Results confirm the presence of respective oxides on anode surface. Their electrocatalytic capability was tested for degradation of 16 priority PAHs in aqueous solution. Results reveal the complete degradation of naphthalene, acenaphthylene, acenaphthene and fluorene without using NaCl electrolyte. While in the presence of NaCl naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene were completely removed. About 98% of total PAHs removal was found at all initial pH values 3, 6, and 9 in the presence of electrolyte. Current study will be helpful in improving quality of petroleum industry wastewater containing PAHs.     

Zinc-Modified ZSM-5 Nanozeolites Synthesized by the Seed-Induced Method: Interrelation of Their Textural,Acidic, and Catalytic Properties in DME Conversion to Hydrocarbons

The effect of the method of introduction of zinc cations and the zinc content in a nanocrystalline zeolite of the ZSM-5 type on the physicochemical and catalytic properties of the material in DME conversion to a mixture of liquid synthetic hydrocarbons has been studied. Zinc is introduced into the catalysts both during the zeolite synthesis and the ion exchange (Zn _n Al _m NZ5 and ZnNZ5, respectively). The use of nanocrystalline Zn _n Al _m NZ5 zeolites provides the formation of a mixture of liquid hydrocarbons with a high selectivity of no less than 90%; the liquid hydrocarbons contain more than 70% of isoparaffins and a small amount of aromatic compounds. An increase in the zinc loading of the Zn _n Al _m NZ5 zeolite from 0.9 to ~3% leads to an increase in the methanol content in the aqueous phase of the liquid product, an increase in the selectivity for liquid hydrocarbons, and a slight increase in the concentration of aromatic and unsaturated hydrocarbons in the mixture. In the presence of the ZnNZ5/Al₂O₃ catalyst with Zn introduced by ion exchange, the methanol content in the aqueous phase and the aromatics content in the liquid hydrocarbon mixture are significantly higher. The Zn _n Al _m NZ5 nanozeolites are characterized by a more developed external surface, a higher concentration of mesopores, and higher acidity.     

海洋生产立管接头特殊螺纹有限元分析

为了适应海洋水下生产立管的苛刻工况,设计了一种顶端张紧式生产立管螺纹接头,并采用有限元接触分析模型对该接头进行了相关的力学分析。通过Abaqus有限元软件计算对比了接箍螺纹与管体强度,模拟立管的上扣过程,计算最佳上扣扭矩,研究了该模型在上扣扭矩、上扣和内压、上扣和拉伸、上扣和拉伸及内压四种载荷下的密封性能。有限元分析结果表明,密封面接触压力随内压的增加而增加,单轴拉伸载荷使得密封面的接触压力有所减小,拉伸载荷和内压共同作用时密封面上的接触压力呈增加趋势,但是增加的幅度要比仅受内压作用时小。该海洋生产立管特殊螺纹的强度优于管体,密封性能可靠,满足设计要求。