Water removal is an essential step during crude oil production due to several problems such as increased transportation costs and high corrosion rate due to dissolved salts. Indirect low frequency ultrasonic energy (US), using baths, has been recently proposed as an effective alternative for crude oil demulsification. However, the reactor position during sonication and its influence on the demulsification efficiency for crude oil has not been evaluated. In this sense, the aim of this study was to develop an automated system based on an open source hardware for mapping the acoustic field distribution in an US bath operating at 35kHz using a hydrophone. Data acquired with this system provided information to evaluate the demulsification efficiency in the different positions of the US bath and correlate it with the acoustic intensity distribution. The automated 3D-mapping system revealed a higher acoustic intensity in the regions immediately above the transducers (ca. 0.6Wcm), while the other regions presented a relatively lower intensity (ca. 0.1Wcm). Experimental data demonstrated that reactors positioned in the most intense acoustic regions provided a much higher efficiency of demulsification in comparison with the ones positioned in the less intense acoustic field regions. Demulsification efficiency up to 93% was obtained with 15min of sonication (100% amplitude) using few amount of chemical demulsifier. Hence, this work demonstrated that the information acquired with the developed mapping system could be used for inducing a higher efficiency of demulsification only by finding the more suitable position of reactor in the US bath, which certainly will help development of appropriate reactors design when looking for such approach.
In this work, high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) using AlCl, InCl, and SrCl molecules was proposed for direct Cl determination in crude oil. Crude oil analysis was performed by pipetting masses of crude oil directly on the graphite platform. Calibration was performed using aqueous standard solutions containing chlorine. A solution containing Sr2+ ions should be used to increase the sensitivity for AlCl and InCl molecules. For SrCl, only Sr2+ solution was used and the graphite platform should be covered with a Zr permanent modifier. Accuracy was evaluated using certified reference material (NIST 1634c, fuel oil) and also by comparison of results obtained with HR-CS GF MAS to those obtained by microwave-induced combustion (MIC), microwave-assisted extraction (MAE), ASTM D6470-99, and neutron activation analysis (NAA). Significant differences were not observed by comparison of results obtained by HR-CS GF MAS to the certified reference value and the other methods for Cl determination (95% confidence level). The AlCl molecule provided the lowest characteristic mass (0.28 ng). Limits of detection (LODs) of 1.4 and 0.5 mg kg–1 of Cl were obtained for AlCl and SrCl molecules, respectively. Sample preparation was minimized using direct analysis of crude oil combined with HR-CS GF MAS providing better LOD when compared to conventional methods for Cl determination. HR-CS GF MAS using AlCl and SrCl molecules was suitable for quality control of crude oil for Cl determination in compliance with the requirements of crude oil industries.
The production and use of nanoparticles (NPs) in different fields increased in the last years. However, some NPs have toxicological properties, making these materials potential emerging pollutants. Therefore, it is important to investigate the uptake, transformation, translocation, and deposition of NPs in plants. In this work, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and micro X-ray fluorescence (μ-XRF) were used to investigate the uptake and translocation of La2O3 NPs to stem and leaves of Pfaffia glomerata (Spreng.) Pedersen after in vitro cultivation of plants in the presence of 400 mg L–1 of La2O3 NPs. By using LA-ICP-MS and μ-XRF, image of the spatial distribution of La in the leaves was obtained, where higher concentration of La was observed in the main veins. Differences in the signal profile of La in leaves of plants cultivated in the presence of bulk La2O3 (b-La2O3) and La2O3 NPs were observed. Sharp peaks of La indicated that NPs were transported to the stems and leaves of plants treated with La2O3 NPs. Both LA-ICP-MS and μ-XRF techniques have shown to be useful for detecting NPs in plants, but LA-ICP-MS is more sensitive than μ-XRF and allowed better detection and visualization of La distribution in the whole leaf.
A method for digestion of soils with high inorganic matter content (ranging from 50 to 92%) by microwave-induced combustion (MIC) is proposed for the first time for further halogens (F, Cl, Br, and I) determination by ion chromatography (IC) and also by inductively coupled plasma mass spectrometry (ICP-MS). Microcrystalline cellulose (100-500 mg), used as a combustion aid, was mixed with sample and water or NHOH solutions (10-100 mmol L) were investigated for analytes absorption. The use of cellulose (400 mg) was mandatory to volatilize the halogens from soils with high inorganic matter. It was possible to use diluted absorbing solutions (up to 100 mmol L NHOH) for halogens retention, providing limits of quantification in the range of 0.06 (I) to 60 (Cl) μg g. Accuracy was evaluated using certified reference materials (CRMs), spiked samples, and pyrohydrolysis method. Recoveries for halogens after spiked samples were in the range of 94 to 103% and the results after digestion of CRMs by MIC were in agreement better than 95% to certified values. Blanks were low, relative standard deviation was below 8% for all soils and no statistical difference was observed for results by pyrohydrolysis and MIC methods showing the feasibility of the proposed method for further halogens determination in soil samples.
In this study, we proposed a method for halogen determination using inductively coupled plasma mass spectrometry (ICP-MS) after partial digestion of soils basically using H2O2 as a reagent for organic matrix composition.
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