Measurement of oilfield chemical residues in produced water discharges and marine sediments

During oil production, significant quantities of water are produced with the crude oil which, following treatment on the platform, are discharged to the marine environment. This produced water contains residues of oilfield chemicals added by the platform operators to the topside processing equipment to aid oil-water separation and mitigate operational problems. The levels of oilfield chemicals entering the marine environment via this route were investigated using electrospray ionisation tandem mass spectrometry (ESI-MS/MS) and wet chemical analysis techniques. The generic nature of different chemical types was shown by ESI-MS/MS. Studies of the partitioning behaviour of corrosion inhibitors and demulsifiers between the oil and water phases of the produced fluids suggested corrosion inhibitors partitioned primarily into the aqueous phase and demulsifiers into the oil phase. This was reflected in levels observed in produced water although, in the case of a corrosion inhibitor, lower than expected concentrations were measured. Scale inhibitors were discharged with the produced water at their dosing concentrations. Marine sediments in the proximity of two North Sea oil platforms contained low levels of benzalkonium quaternary ammonium salts (0.74-10.84 ng/g), typical corrosion inhibitor chemicals.     

Affinity separation of enzymes from mixtures containing suspended solids

Agarose beads containing immobilized enzymes or affinity ligands have been made magnetically responsive by adsorbing freshly precipitated magnetite on their surface. These beads are used for affinity adsorption of proteins from complex mixtures containing suspended solids. The magnetically responsive beads and the unwanted (diamagnetic) solids are then separated by magnetic filtration. This magnetic adsorption scheme for direct affinity separation of enzymes from mixtures containing suspended solids is compared with a similar, but nonmagnetic, scheme in which the affinity matrix is supported on fiberglass cloth. The enzyme is allowed to adsorb in this matrix, and the matrix is simply removed physically from the suspension to achieve separation from the unwanted solids. The two methods seem comparable in their ability to separate a desired enzymatic activity. The magnetic methods are technically the more complex of the two, but are significantly the more rapid. The efficiency of separation of diamagnetic and ferrimagnetic solids in these biological systems by high gradient magnetic filtration is good.     

Differential thermal analysis of transitions in finely-divided solids suspended in liquid media

The experimental difficulties associated with differential thermal analysis (DTA) are reviewed. Quantitative work has always required calibration of the equipment, and conventional solid diluents have serious disadvantages. It is shown that calibration is not strictly necessary, given appropriate conditions. Dilute suspensions of polymer crystals in organic liquids provide ideal media for DTA when used as diluent and as reference material. Convection currents are suppressed and the medium can support fine particles of the solid under test, even when the solid has a relatively high specific gravity. The new theory and techniques have been tested experimentally by measuring the heats of fusion of two inorganic salt hydrates. The results are in excellent agreement with literature values. A novel arrangement with a double thermocouple junction is shown to have considerable potentialities as a means of making precise measurements quite simply.     

Analysis of BTEX, PAHs and metals in the oilfield produced water in the State of Sergipe, Brazil

During oil and gas exploitation, large amounts of produced water are generated. This water has to be analyzed with relation to the chemical composition to deduce the environmental impact of its discharge after a treatment process. Therefore, a study was carried out to evaluate preliminarily the BTEX (benzene, toluene, ethylbenzene and xylenes), polycyclic aromatic hydrocarbons (PAHs) and metals contents in produced water samples taken from effluents of the Bonsucesso treatment plant located in the city of Carmópolis, the most important oil and gas producer in the State of Sergipe, North-east of Brazil. Three methods were optimized to determine the target compounds. Polycyclic aromatic hydrocarbons were determined by gas chromatography with mass spectrometric detection (GC/MS), volatile aromatic hydrocarbons (BTEX) by gas chromatography with photoionization detector (GC/PID) and metals were analyzed by flame atomic absorption spectrometry (FAAS). The results showed that concentrations of the target compounds in these samples ranged from 96.7 to 1397 μg L^− 1 for BTEX, from 0.9 to 10.3 μg L^− 1 for PAHs and from 0.003 to 4540 mg L^− 1 for metals.     

Characterization of water adsorption onto carbonaceous materials produced from food wastes

The recycling of organic wastes has become very important and the development of technology for recycling organic wastes needs to sustain industrial development. In this study, techniques for producing carbonaceous materials from organic wastes are described and water adsorption is characterized. The organic wastes used are coffee grounds and oolong tea leaves carbonized at 673 to 1073 K. The iodine adsorption capacity of the carbonaceous materials increased with increased carbonization temperature. The amount of water adsorbed onto the carbonization materials produced from oolong tea leaves at 873 K for 2 h was the highest. The Freundlich constant 1/n and the differential heat of adsorption of the carbonaceous materials produced from oolong tea leaves were greater than that of the carbonaceous materials produced from coffee grounds. The ability to humidity control can be estimated by the difference between the amount of water adsorbed relative pressure 0.90 and that at relative pressure 0.55. The ability to humidity control was the greatest for the carbonaceous materials produced from the oolong tea leaves at 873 K for 2 h and did not depend upon the adsorption temperature. These results indicated that the carbonaceous materials produced from oolong tea leaves at 873 K for 2 h could have more humidity control.     

Automated prevalve sample filtration in flow injection analysis: Determination of sulphate in water removing suspended solids and colour before sampling

Summary Suspended solids and the presence of organic substances and colour are the main interferences in the turbidimetric spectrophotometric determination of sulphate at 420 nm in water. An automated flow-injection procedure is proposed in which these interferences are automatically removed by using an active carbon filter, which is incorporated in the flow system between the sampler and the sampling valve system. With this automated prevalve sample filter the proposed turbidimetric method gives the same results as a standard flow injection and an automated segmented method where the above mentioned interferences are manually removed prior to sampling. The method is applicable for the analysis of sulphate in surface, ground and domestic waters in the concentration range up to 200 mg/l at a sampling rate of up to 60 samples per hour with a coefficient of variation of better than 1%.

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Automatische Filtration vor dem Probeneinlaßventil in der Fließ-Injektionsanalyse: Entfernung von Festsubstanzen und Farbstoffen bei der Sulfatbestimmung in Wasser

Zusammenfassung Suspendierte Feststoffe, organische Substanzen und Farbstoffe stellen die Hauptstörquellen bei der turbidimetrisch-spektralphotometrischen Sulfatbestimmung bei 420 nm dar. Bei dem vorgeschlagenen Fließ-Injektionsverfahren werden diese Störungen automatisch mit Hilfe eines Aktivkohlefilters entfernt, das zwischen Probengeber und Probenventil angeordnet ist. Mit dem vorgeschlagenen System werden die gleichen Ergebnisse erhalten wie mit einer Standardmethode sowie einem Segmentierungsverfahren mit manueller Entfernung der Störungen vor der Probeneingabe. Die neue Methode eignet sich für die Sulfatbestimmung in Oberflächen-, Grund- und Haushaltswasser bis zu 200 mg/l bei einer Geschwindigkeit von 60 Proben je Stunde. Der Variationskoeffizient ist besser als 1%.

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Part of this paper was presented by J. F. van Staden at the 182nd ACS National Meeting, New York, N.Y., 23–28 August 1981; Division of Analytical Chemistry; Section A. Symposium on flow injection and other unsegmented continuous-flow sample processing systems. Abstract No. 23     

Thermodynamics of water intrusion in nanoporous hydrophobic solids

We report a joint experimental and molecular simulation study of water intrusion in silicalite-1 and ferrerite zeolites. The main conclusion of this study is that water condensation takes place through a genuine first-order phase transition, provided that the interconnected pores structure is 3-dimensional. In the extreme confinement situation (ferrierite zeolite), condensation takes place through a continuous transition, which is explained by a shift of both the first-order transition line and the critical point with increasing confinement. The present findings are at odds with the common belief that conventional phase transitions cannot take place in microporous solids such as zeolites. The most important features of the intrusion/extrusion process can be understood in terms of equilibrium thermodynamics considerations. We believe that these findings are very general for hydrophobic solids, i.e. for both nonwetting as well as wetting water-solid interface systems.     

Molecular simulations of water in hydrophobic microporous solids

This work reports Grand Canonical Monte-Carlo molecular simulation (GCMC) results of water adsorption in a priori hydrophobic microporous solids such as silicalite, a purely siliceous zeolite (Ø_pore～5 Å) and C-Y, a pure carbon replica of zeolite Y (Ø_pore～1 nm). At a first step, in both cases, the water-water interactions are described with the SPC model (calibrated for bulk liquid water) while water-substrate interactions are calculated within the framework of the PN-TrAZ model. This adsorbate-zeolite potential decomposes into short range (repulsive, inductive and dispersive) interaction terms with transferable parameters plus, in the case of silicalite, an electrostatic interaction term based on SPC partial charges for water and ab initio charges for silicalite. With such a standard approach, we found that water fills the microporous volume in both materials at pressure value well below P ₀; hence does not show a strong hydrophobic behaviour at variance with reference experiments (V. Eroshenko et al. in C. R. Phys. 3:111, 2002). This indicates that common models used to describe confined polar molecules are far from being operative. We show on the basis of periodic ab initio calculations that confined water molecules in silicate have a dipole value ～10% smaller than that in the 3D liquid phase indicating that the environment felt by a confined water molecule in silicalite pores is not equivalent to that in the bulk liquid. This implies that classical simulations of polar molecules in ultra confining environment should rely on polarizable potentials (K.S. Smirnov, D. Bougeard in Chem. Phys. 292:53, 2003) if one wishes to capture the underlying physics. Reducing the SPC water dipole moment by 5% in GCMC calculations does allow reproducing experimental data.     

Low levels of 134Cs in suspended solids in rivers discharging into the Sea of Japan

Journal of Radioanalytical and Nuclear Chemistry - We investigated radiocesium concentrations in the suspended solids (SS) of two large rivers discharging into the Sea of Japan. Higher 134Cs...     

Extractability of dioxins from suspended substances in distributed water

The extractability of dioxins from suspended substances (SS) in distributed water was evaluated. Dioxins adsorbed on the collected SS were extracted by pressurized liquid extraction with various solvents. High-polarity solvents (acetone, alcohols) extracted considerably higher amounts of some lower-chlorinated dibenzo-p-dioxins (LoCDDs) than did low-polarity solvents (dichloromethane, toluene), whereas the extracted amounts of higher-chlorinated dibenzo-p-dioxins (HiCDDs) were roughly the same, regardless of the solvent. The extractability of the LoCDDs depended on the isomer. Daily variations in quantities for PCDDs, organic matter (OM), and iron in the SS were examined, and the results suggested that in the SS, LoCDDs and HiCDDs were associated, respectively, with raw water-derived organic matter and microparticles sequestered in iron oxy(hydr)oxide floc. It was also suggested that the low extractability of certain congeners was not attributable to the enormously coexisting ferric compounds but was probably attributable to OM with which they strongly associate.     

Kinetics of hydrate formation using gas bubble suspended in water

An innovative experimental technique, which was devised to study the effects of temperature and pressure on the rate of hydrate formation at the surface of a gas bubble suspended in a stagnant water phase, was adapted in this work. Under such conditions, the hydrate-growth process is free from dynamic mass transfer factors. The rate of hydrate formation of methane and carbon dioxide has been systematically studied. The measured hydrate-growth data were correlated by using the molar Gibbs free energy as driving force. In the course of the experiments, some interesting surface phenomena were observed.     

Sorption of anthropogenic radionuclides onto river sediments and suspended solids: dependence on sediment composition

Journal of Radioanalytical and Nuclear Chemistry - The purpose of the study is to explore the sorption behaviour of anthropogenic radionuclides in the Vltava River catchment in the Czech Republic,...     

Polyacrylonitrile-grafted Plantago psyllium mucilage for the removal of suspended and dissolved solids from tannery effluent

Grafted copolymer of Plantago psyllium mucilage and acrylonitrile (Psy–g–PAN) has been synthesized in the presence of nitrogen using a ceric ion–nitric acid redox system. The solid removal efficiency of this copolymer was tested with tannery effluent. The suitable pH, optimum dose of polymer and contact time for the maximum removal of suspended (SS) and dissolved solids (TDS) are reported. The optimum dose was found to be 1.2 mg l^?1. The suitable pH values, at which a maximum SS removal of about 89% and TDS removal of about 27% occurred, were found to be 7.0 and 9.2 for SS and TDS, respectively. The optimum treatment duration was 3 h. The analysis of X-ray diffraction patterns of Psy–g–PAN and solid waste from effluent before and after treatment suggests the interaction of the solid waste with the Psy–g–PAN copolymer.