Determination of cadmium, lead, and nickel by simultaneous multielement flame atomic absorption spectrometry in burned and unburned Venezuelan crude oil

This work describes the use of simultaneous multielement flame atomic absorption spectrometry for the determination of cadmium, lead, and nickel in burned and unburned Venezuelan crude oil (5 ml volumes) in controlled laboratory experiments. The simultaneous detection limits were 0.010 mug ml(-1) (Cd), 0.04 mug ml(-1) (Pb), and 0.40 mug ml(-1) (Ni) with precision's of these elements at concentrations of 10x above these detections limits, and in the crude oil, of 1-2%. Loss of elemental concentrations in the crude oil in a 3-5 ml volume when burned were 4% (Cd), 50% (Pb), and 22% (Ni). These results suggest that the form of the elements and the temperature attained in the burning crude oil effect the removal of the elements. The type of surface affected the volume of oil removed. Soil gave a 15% and a smooth surface almost 50% volume reduction.     

正交试验在原油重金属元素测定中的应用

采用微波消解技术,以ICP-AES同时测定原油中V、Ni、Mn、Pb重金属元素的含量。该方法回收率在94.73%～107.2%之间,相对标准偏差小于2.12%,适用于原油中各种重金属元素的测定。采用正交设计法安排实验,可以以少量的实验次数获得大量信息,既节省时间又节约药品。同时利用原油样品中的V/Ni的比值作为参数,可判断原油油源的特征及地质特点。     

Trace elements in Nigerian oil sands and extracted bitumens

The Nigerian oil sands are very extensive with an estimated in place reserves of bitumen/heavy oil of over 30 billion barrels. Instrumental Neutron Activation Analysis (INAA) has been used to determine the trace and minor elements in the raw oil sands and bitumens. About 43 trace elements in the raw oil sands and 30 in bitumen extracts were determined. The results are compared with values of Canadian bitumens and some Nigerian conventional light crude oils. In general, the Nigerian bitumens has higher hydrocarbon concentration than the Athabasca bitumen but slightly lower than in the Nigerian crude oils. The sulphur, vanadium and nickel contents of the Nigerian bitumens and crude oils are appreciably lower than those of Athabasca bitumen, thus indicating that the extraction and refining of Nigerian tar sand oil would pose less technological and environmental problems than the Athabasca syncrude.     

Multi-element analysis of Ghanaian crude oils by instrumental neutron activation analysis

Instrumental neutron activation analysis based on thermal neutrons from the Ghana Research Reactor-1 facility was utilized to analyze 18 trace elements namely Al, As, Br, Ca, Cd, Cl, Co, Cu, Fe, K, Mg, Mn, Na, Ni, S, Si, V, and Zn in two different crude oil samples from the Saltpond and Jubilee field in the Saltpond, Central region and Cape Three Points, Western region of Ghana, respectively. The sulfur concentration for both samples were low and within globally accepted range of 0.1–0.5%wt for sweet crude oil. The results of the elemental analysis showed that the two samples are relatively low in trace element concentrations compared to crude oils of other countries. Higher Fe concentration in the Jubilee crude oil indicates younger oil. The V/Ni ratios obtained for crude oils from both locations imply a possible marine organic origin and also suggest the Saltpond crude oil is more matured than the Jubilee crude oil.     

微波灰化-电感耦合等离子体原子发射光谱法测定原油中的金属元素

采用微波灰化技术消化原油样品,并使用电感耦合等离子体原子发射光谱法(ICP-AES)测定其中Na、Mg、Ca、Fe、V、Ni和Cu的含量。探讨了原油样品中金属元素测定的称样量和微波灰化程序,并优化了仪器工作参数和实验条件。样品经微波灰化处理后,用盐酸溶解残渣,方法对Na、Mg、Ca、Fe、V、Ni和Cu元素的检出限分别为0.07、0.01、0.01、0.01、0.02、0.04和0.03mg/kg,回收率在84.5%～96.6%之间,相对标准偏差在2.1%～6.9%范围。方法简便、可靠,可用于原油中Na、Mg、Ca、Fe、V、Ni和Cu 7种金属元素的检测。     

Modeling of cumulative release on long term leaching behaviour of selected oil sludge from crude oil terminal and petroleum refining plant

Management of oil sludge containing environmentally toxic elements is a major problem in crude oil processing industry. Oil sludge samples from the petroleum refinery plant in Melaka and crude oil terminal in Sarawak were analysed. The aim of present work is to study long term leaching behaviour of arsenic (As), cobalt (Co), chromium (Cr) and zinc (Zn) from oil sludge. Tank leaching test was carried out and the samples were analysed using inductively coupled plasma-mass spectrometry (ICP-MS). The results were studied using LeachXS software to plot the graphs of elements concentration in order to study the leaching behaviour of toxic elements in oil sludge. The long term leaching (100 years) modeling was calculated using equations referred to National Institute of Public Health and the Environment Bilthoven (RIVM) and the results were plotted for cumulative release in different areas of oil sludge. Tank leaching test of the oil sludge samples from petroleum refinery plant in Melaka showed concentrations of As, Co, Cr and Zn ranging from 0.205 to 1.102, 0.031–0.454, 0.016–0.086 and 0.409–8.238 mg/l, respectively while the concentrations of As, Co, Cr and Zn in oil sludge samples from crude oil terminal in Sarawak were in the range of 0.002–0.089, 0.001–0.033, 0.006–0.016 and 0.100–2.744 mg/l, respectively. On the other hand, results on cumulative release from the modeling of long term leaching (100 years) showed that As, Co, Cr and Zn concentrations were proportional to the quantity of oil sludge. In conclusion, during extrapolation of release of toxic elements using the data in the laboratory, several other factors were taken into account to suit environmental conditions such as soil moisture, the negative logarithm of the effective diffusion coefficient (pD_e) and temperature, while the long-term behaviour of As, Co, Cr and Zn was proportional to the quantity of oil sludge to be disposed off.     

Spectrochemical study for the in situ detection of oil spill residues using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) has been used to identify the differences or similarities between crude oil and fuel residues. Firstly, a man portable LIBS analyzer was used for the on-site environmental control and analysis of the oil spill from The Prestige. An exhaustive analysis of crude oil and oil spill residues (collected during the field campaign in the Galician Coast) was performed in the laboratory. Characteristics elements in petroleum such as C, H, N, O, Mg, Na, Fe and V were detected. In addition, contributions from Ca, Si and Al in the composition of residues have been found. The use of intensity ratios of line and band emissions in the original fuel (crude oil) and in the aged residues allowed a better characterization of the samples than the simple use of peak intensities. The chemical composition between the crude oil and the fuel residues was found completely different. As well, a statistical method was employed in order to discriminate residues. Although significant differences were observed, no conclusions in terms of age and provenance could be reached due to the unknowledgment in the origin of the samples.     

Present-day methods for the determination of trace elements in oil and its fractions

The development and use of instrumental methods for the determination of a wide range of trace elements in oil is considered. Special attention is paid to methods of the direct introduction of samples into spectrometers. It is shown that preliminary sample preparation is in certain cases necessary for the determination of trace elements in oil. The main methods of sample preparation of oils, including methods of extraction of a series of trace elements from crude oil (extraction, membrane, sorption, etc.), are described.     

Counter-current chromatography for oil analysis: Retention features and kinetic effects

Application of counter-current chromatography (CCC) for oil analysis has been suggested for the first time. CCC looks very promising as a tool for pre-concentration and isolation of trace elements from oil. Features of stationary phase retention of two-phase liquid systems (oil or oil products–aqueous nitric acid solutions) in CCC have been investigated. The influence of physicochemical properties of crude oil and oil products used as a mobile phase on the volume of stationary phase (acidic aqueous solutions) retained in CCC was studied. Chromatographic behavior of several oil samples was studied. It has been shown that physicochemical properties of test oil influence its chromatographic behavior. Optimal values of density and viscosity (ρ < 0.85 g/cm³, n < 7 cSt) of crude oil and oil products that could be analyzed using CCC were estimated. The influence of the column rotational speed and flow rate of mobile phase on the stationary phase retention was also investigated. It is known that kinetic aspects (mass transfer of elements between phases) can play a very important role in selecting an optimal composition of stationary phase for the pre-concentration of elements from oil. The influence of nitric acid concentration in the stationary phase on mass transfer was studied. Kinetic characteristic for trace element recovery has been investigated for the optimization of pre-concentration conditions of trace elements from crude oil and oil products. The extraction recoveries of Zn, Mn, Fe, Ni, V, Cu, Cd, Pb and Ba by CCC in dynamic mode are in the range of 75–95% while they are lower than 35% under batch conditions.     

Trace element determinations in shale oil products by neutron activation

Neutron activation offers some important advantages for the determination of selected trace elements in shale oil products. This paper gives techniques and results of a study of crude shale oil and naphtha, heavy distillate, and wax products of shale oil. The elements determined were Al, As, Au, Br, Ce, Cl, Co, Cr, Fe, Hg, I, K, Mn. Mo, Na, S, Sb, Se, V, and Zn. Some elements (Mn, Na, As) tend to accumulate in heavier fractions, whereas chlorine and iodine are concentrated in the more volatile fractions. The volatility of sulphur compounds in the shale oil products appears to be essentially uniform, with some tendency toward accumulation in distillation residues. The tendency for the trace elements to accumulate in the waxes that precipitated from cooled heavy distillates was very low.     

Trace element determination in crude oil and its fractions by inductively coupled plasma mass spectrometry using ultrasonic nebulization of toluene solutions

A method was developed for the determination of trace elements in crude oil by inductively coupled plasma mass spectrometry (ICP-MS) after sample dissolution in toluene and subsequent ultrasonic nebulization (USN). Carbon build-up at the interface and ion lenses was minimized by optimization of the argon to oxygen ratio in the plasma and by the desolvating action of the USN. The analyte addition technique, combined with internal standardization (¹¹⁵In), was the only calibration procedure capable to correct properly for signal suppression, especially observed in solutions with higher concentrations of asphaltenes. Analytical curves with good linearity (r²>0.99), and solution detection limits (LOD–3σ) of 0.1 μg l⁻¹ for V, Ni, Co, Y, Mo, Cd, Ba and La, and in the range of 0.1–1 μg l⁻¹ for Al, Ti, Fe, Zn, Sr, Ag, Sn and Pb were obtained. Method validation was performed by analyzing two certified reference materials. For National Institute for Standards and Technology (NIST) 1634c (V, Ni, Co), accuracy was approximately 10%, similar as observed for other 12 elements in NIST 1084a. Asphaltenes were separated from the oil bulk of crude oil samples from the Potiguar Basin (Brazil) using precipitation in heptane. The heptane-soluble fraction (maltenes) was separated by elution chromatography into three sub-fractions: (1) saturated and low molecular mass (MM) aromatics, (2) aromatics and low MM polar compounds, and (3) high MM polar compounds (resins). Trace elements were determined in these fractions after dissolution in toluene, by USN–ICP-MS. Mass balance calculations showed a significant increase of most elements (10–30 times) in the asphaltenic fraction, and in minor proportions in fraction 3, compared to the crude oil samples. Comparison with microwave-assisted acid decomposition showed good agreement, validating the proposed methodology and emphasizing its applicability for routine analysis of crude oil and other toluene soluble petroleum products.     

直接稀释进样-电感耦合等离子体原子发射光谱法同时测定原油中20种元素

原油样品(2.0g)用稀释剂航空煤油稀释至20.0g后,直接进样供电感耦合等离子体原子发射光谱法测定其中银、铝、硼、钡、钙、镉、铬、铜、铁、镁、锰、钼、钠、镍、铅、硅、锡、钛、钒和锌等20种元素的含量。在优化的试验条件下,20种元素的检出限(3S/N)在0.1～3mg·kg-1之间。方法用于分析原油样品,所得测定值的相对标准偏差(n=6)在1.24%～6.23%之间,回收率在80%～105%之间。     

催化裂化催化剂中微量金属元素的测定

原料油中的微量金属元素会污染催化裂化催化剂而使其中毒,对于使用中的再生、平衡催化裂化催化剂进行微量金属元素含量分析,可以有效地指导炼油厂的生产．通过对检出限、重复性以及准确性的考察．表明等离子发射光谱法测定催化剂中微量金属元素含量检出限低、重复性好、准确度高、且具有多元素同时测定以及线性范围宽的特性,是催化裂化催化剂中金属元素含量快速测定的最有效方法之一．     

Spectroscopic and Chromatographic Identification of Hydrocarbon Group Types in Pakistani Crude Oils

Two crude oil samples collected from Paniro and Tangri (Sindh) southern Pakistan. The distillate fractions of both crude oil samples were analysed by U.V‐visible spectrophotometer and column chromatography for hydrocarbon group types. It was found from the physico‐chemical study of these crude oils that Tangri crude oil contains mostly paraffinic contents while Paniro crude oil samples are rich in aromatics. It was concluded from all the experiments that Tangri crude oil is paraffinic in nature; while Paniro crude oil is naphthenic in nature, further it was observed that Tangri crude oil processing would be environmentally friendly compared to Paniro crude oil, because Paniro crude contains a high amount of polyaromatics.     

不同原油中金属元素的测定及聚类分析

采用二氯甲烷溶解、分散原油样品,以浓HNO3-H2O2为消解体系,采用微波法对原油进行消解,利用电感耦合等离子体质谱法(ICP-MS)测定原油中的V、Ni、Cu、Fe、Cr、Zn、Pb、Co、Mo、Ag等17种微量金属元素;并以 6Li、45Sc、72Ge、89Y、115In、159Tb、209Bi为内标元素,补偿基体效应,选择适当的待测元素同位素克服质谱干扰,优化了实验条件.结果表明,原油中大多微量金属元素的检出限达到ng/L,仅Fe、As、Sb 3种元素的检出限相对较高;各元素线性关系良好,相关系数r不低于0.999 5;方法精密度较高,相对标准偏差(RSD)不大于5.0%,准确度较好,相对误差不高于10%.对不同原油样品以Ni/V与Fe/V值为变量进行聚类分析,结果发现,国内与国外不同地区原油样品具有明显差异性.     

Separation and Chemical Characterization of Wetting Crude Oil Compounds

To improve the understanding of wettability, especially the influence of colloidal stability and composition of crude oil, wetting experiments on quartz sand were performed with an asphaltene-rich oil, a resin-rich oil, and with model oils containing different colloid compositions. A two-step procedure was developed to investigate the wetting behavior. In the first step those crude oil components were extracted, which preferentially wet solid surfaces. The extracted crude oil components were characterized in the second step. The amount of adsorbed oil components correlates with the stability of the crude oil colloids: low colloidal stability of crude oil leads to larger amounts of adsorbed components than does high colloidal stability. The addition of resins and/or low molecular weight asphaltenes to the crude oil stabilizes the crude oil colloids; i.e., a lower amount of wetting components are isolated by extraction in such systems. To find out, which fraction of the adsorbed oil components determines the wetting behavior of a crude oil, the wetting properties of the toluene solutions of these fractions were compared to those of the toluene solutions of the precipitated crude oil colloids. The fractions extracted with the solvent systems chloroform and methanol/chloroform showed nearly the same wetting behavior as the crude oil colloids. These fractions are characterized by the highest molecular weights, higher sulfur compositions, and the lowest H/C ratios. On the other hand, the nitrogen compounds predominate in the acetone fraction.     

The determination of lead, nickel and vanadium in Saudi Arabian crude oil by sequential injection analysis/inductively-coupled plasma mass spectrometry

The coupling of sequential injection with inductively-coupled plasma mass spectrometry as an analytical tool for trace element detection is described. The technique is applied for determining the concentrations of lead, nickel and vanadium at part per billion levels in sample solutions of Saudi arabian crude oils. A microemulsion crude oil sampling procedure and a standard addition method using oil-soluble organo metallic salts of trace elements were used. A reference oil sample (NBS 1634b) was analyzed to obtain the accuracy and precision of the method. Results showed percentage recovery values of 98.2%, 95.7% and 101.4% and standard deviations of 2.9%, 1.5% and 2.0% for lead, nickel and vanadium respectively. The method is sensitive, requires only small sample volumes and is quick.     

Determination of Mo, Zn, Cd, Ti, Ni, V, Fe, Mn, Cr and Co in crude oil using inductively coupled plasma optical emission spectrometry and sample introduction as detergentless microemulsions

A procedure to prepare crude oil samples as detergentless microemulsions was optimized and applied for the determination of Mo, Zn, Cd, Si, Ti, Ni, V, Fe, Mn, Cr and Co by ICP OES. Propan-1-ol was used as a co-solvent allowing the formation of a homogeneous and stable system containing crude oil and water. The optimum composition of the microemulsion was crude oil / propan-1-ol / water / concentrated nitric acid, 6 / 70 / 20 / 4 w/w/w/w. This simple sample preparation procedure together with an efficient sample introduction (using a Meinhard K3 nebulizer and a twister cyclonic spray chamber) allowed a fast quantification of the analytes using calibration curves prepared with analyte inorganic standards. In this case, Sc was used as internal standard for correction of signal fluctuations and matrix effects. Oxygen was used in the nebulizer gas flow in order to minimize carbon building up and background. Limits of detection in the ng g^− 1 range were achieved for all elements. The methodology was tested through the analysis of one standard reference material (SRM NIST 1634c, Residual Fuel Oil) with recoveries between 97.9% and 103.8%. The method was also applied to two crude oil samples and the results were in good agreement with those obtained using the acid decomposition procedure. The precision (n = 3) obtained was below 5% and the results indicated that the method is well suited for oil samples containing low concentrations of trace elements.     

Detection of heavy metals in Arabian crude oil residue using laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was applied for the elemental analysis of Arabian crude oil residue samples. The spectra due to trace elements such as Ca, Fe, Mg, Cu, Zn, Na, Ni, K and Mo were recorded using this technique. The dependence of time delay and laser beam energy on the elemental spectra was also investigated. Prior to quantitative analysis, the LIBS system was calibrated using standard samples containing these trace elements. The results achieved through this method were compared with conventional technique like inductively coupled plasma.     

Determination of 18 trace elements in petroleum and its derivatives by neutron activation with a small nuclear reactor

Non-destructive neutron activation has been used to analyze 6 different samples of crude oil and heating oil, from Western Canada and Venezuela. These samples were irradiated with thermal neutrons for 2, 30 and 240 min in the SLOWPOKE reactor and the concentrations of 18 trace and minor elements (Al, As, Br, Cl, Co, Dy, Eu, Fe, I, La, Mn, Mo, Ni, Na, S, Se, Sm and V) ranging from 0.6 ppb to 2.24% have been measured. Eleven elements (As, Br, Co, Cl, Fe, Mo, Mn, Na, Ni, S and V) were determined in the fuel oil (SRM-1634) obtained from the National Bureau of Standards and were found to be in good agreement with the values certified by NBS