An ionic liquid-based microextraction method for the determination of Cu and Ni in high-salinity produced water from offshore petroleum exploration by GF AAS

Abstract

This work reports the development of a novel method for the ionic-liquid microextraction and determination of Cu and Ni in high-salinity produced water by Graphite Furnace Atomic Absorption Spectrometry (GF AAS). Studies were performed to set a suitable temperature program and to optimize the extraction conditions. Due to the presence of the ionic liquid in the extracts, a drying temperature of 300 C was chosen for the temperature program. The pyrolysis and atomization curves indicated that the pyrolysis temperature for Cu and Ni should be set at 900 C, and that the best atomization temperatures were 2100 and 2500 C for Cu and Ni, respectively. Ionic-liquid microextraction was carried out by mixing 10 mL of sample with 1 mL of a 1% m/v ammonium pyrrolidine dithiocarbamate (APDC) solution and 1 mL of a Britton-Robinson buffer solution (total concentration 0.1 mol L À1 ) with pH ¼ 4.0. Then, 100 mL of the ionic liquid (1-hexyl-2methylimidazolium-hexafluorophosphate, C 6 MImPF 6 ) were added and the mixture was shaken manually for 2 min. The obtained suspension was centrifuged for 15 min at 4500 rpm in order to promote the sedimentation of the ionic liquid. The ionic-liquid was separated from the upper aqueous phase using a micropipette and then, absolute ethanol enough to complete 1 mL was added. This final solution was introduced into the graphite tube for the determination of Cu and Ni. The method presented limits of quantification of 0.37 and 0.61 mg L À1 for Cu and Ni, respectively. The calibration of the method was possible using a matrix-matching approach using synthetic saline samples. Recovery tests were performed with the addition of aqueous standard solutions of the metal cations and resulted in the recovery percentages in the range of 76 -126%.

Determination of scaling ions in oilfield produced water by laser-induced breakdown spectroscopy

“…Laser-Induced Breakdown Spectroscopy (LIBS), typically employed in solid sample analysis, has proved to be also efficient for liquid analysis. 12–15 Compared to the conventional elemental analysis techniques such as Inductively Coupled Plasma Atomic Emission Spectrometry (ICP OES) 16,17 and Atomic Absorption Spectrometry (AAS), 18 LIBS offers several advantages that include minimal or no sample preparation, quick and simple measurements and multielement analysis. 19 Due to the high portability potential of the LIBS instrumentation, it could be implemented on oil platforms, generating a faster and in loco response to the scaling potential of produced waters.…”

Determination of cobalt in high-salinity reverse osmosis concentrates using flame atomic absorption spectrometry after cold-induced aggregation microextraction

“…Liquid-phase microextraction techniques based on ionic liquids (ILs) have been recently applied for the preconcentration and determination of metals. [27][28][29][30] Among the preconcentration techniques, coldinduced aggregation microextraction (CIAME), which was proposed by Baghdadi and Shemirani, 31 proved to be a robust procedure against the high content of salt. 32 In this technique, an ionic liquid is dissolved in the sample at an elevated temperature.…”

Determination of phenolic acids in Prunella vulgaris L.: a safe and green extraction method using alcohol-based deep eutectic solvents

“…Until now, the number of available green solvents for extracting natural products has been rather limited. In this sense, some of these new "Green Solvents" including water, 12 supercritical uids 13 and ionic liquids (ILs) 14,15 have received growing interest over the last two decades. 16 Water and supercritical uids like scCO 2 are benecial because they are nontoxic, relatively inert, and easily removable when applied to extracting natural products.…”