Flat membrane-based electromembrane extraction coupled with UV–visible spectrophotometry for the determination of diethylhexyl phthalate in water samples

A new approach for cobalt (II) removal from simulated wastewater using electro membrane extraction with a flat sheet supported liquid membrane

The aim of this work was to efficiently remove cobalt (Co) from aqueous solutions by using a novel Electromembrane Extraction (EME) technique. This novel electrochemical cell design featured two distinct glass chambers, incorporating a Supported Liquid Membrane (SLM) composed of a polypropylene flat membrane saturated with 1-octanol and a carrier substance, as well as electrodes constructed from graphite and stainless steel. The investigation covered an exploration of various effective parameters like, carrier type, voltage across the cell, donor solution pH, and the initial Co concentration, with the overarching goal of comprehending their individual effect on Co removal efficiency. Notably, two different carriers, tris(2-ethylhexyl) phosphate (TEHP) and bis(2-ethylhexyl) phosphate (DEHP), were systematically evaluated in combination with 1-octanol. The findings underscored the pivotal role of the cell voltage in significantly enhancing the mass transfer rate of cobalt across the membrane, thereby advancing the effectiveness of the removal process. After a comprehensive optimization process, the optimal operating conditions were established as follows: employing 1-octanol with 1.0 % v/v bis(2-ethylhexyl) phosphate as a carrier, applying a voltage of 60 V, maintaining an initial pH of 5, utilizing an initial cobalt concentration of 15 mg/L, conducting an extraction for 6 h, and employing a stirring rate of 1000 rpm. Remarkably, these conditions led to the attainment of an impressive removal efficiency of 87 %. In stark contrast, when no voltage was applied, the removal efficiency did not surpass 40 %. This underscores the pivotal role of the applied voltage in enhancing the cobalt removal process under the specified conditions.

Environmental Applications of Electromembrane Extraction: A Review

Electromembrane extraction (EME) is a miniaturized extraction technique that has been widely used in recent years for the analysis and removal of pollutants in the environment. It is based on electrokinetic migration across a supported liquid membrane (SLM) under the influence of an external electrical field between two aqueous compartments. Based on the features of the SLM and the electrical field, EME offers quick extraction, effective sample clean-up, and good selectivity, and limits the amount of organic solvent used per sample to a few microliters. In this paper, the basic devices (membrane materials and types of organic solvents) and influencing factors of EME are first introduced, and the applications of EME in the analysis and removal of environmental inorganic ions and organic pollutants are systematically reviewed. An outlook on the future development of EME for environmental applications is also given.

An overview on nanostructure-modified supported liquid membranes for the electromembrane extraction method

Electromembrane extraction (EME) is an extraction method on the micro scale, in which charged compounds are extracted from a donor phase (sample solution) into an acceptor phase via a supported liquid membrane (SLM) containing a water-immiscible organic solvent. To enhance the extraction efficiency and selectivity in this method, some studies have focused on the modification of the SLM, and thus many strategies have been reported for this purpose. One of these techniques is the introduction of nanomaterials in the SLM structure, which can enhance the extraction efficiency. In the current study, the different nanostructures used for SLM modification in the EME method are reviewed. Furthermore, the related analytical parameters of the developed techniques are classified and tabulated. It is hoped that this review will motivate further research in this field using other nanostructures.

Electrospun Polyacrylonitrile/Clinoptilolite Coating for SPME of PAHs from Water Samples

Electrospun polyacrylonitrile/clinoptilolite (PAN/CP) nanofibers were used to extract polycyclic aromatic hydrocarbons (PAHs) (acenaphthene, acenaphthylene, naphthalene, and phenanthrene) from water samples by solid-phase microextraction (SPME). The target PAHs was detected and quantified by gas chromatography equipped with a flame ionization detector. The PAN/CP fibrous coating with uniform morphology and without beads was electrospun after optimizing the electrospinning parameters by the Taguchi method. Thermogravimetric analysis of PAN/CP nanofibers indicated that the nanofibers are thermally stable up to 357°C. The effective parameters that affect the extraction by SPME were optimized using the response surface methodology based on the central composite design. The limits of detection and limits of quantification by the proposed method were 0.10-0.32 and 0.45-1.12 ng mL-1, respectively. The relative standard deviations were below 12%. The method was assessed for extracting PAHs from real samples including agricultural water, rainwater and spring water. The obtained relative recoveries were higher than 86%.

Application of reusable flat-membrane in electro-membrane extraction for tamsulosin hydrochloride determination in cleaning validation samples of sterile production line equipment by RP-HPLC

In order to ensure compliance with the current Good Manufacturing Practice (cGMP), cleaning process of pharmaceutical manufacturers should be validated. This study was aimed to utilize a reusable flat-membrane in the electromembrane extraction (EME) for isolation of tamsulosin hydrochloride (TMS) from rinse samples of sterile production of pharmaceutical line. Moreover, validation of mentioned method was done. The residual concentration of TMS was determined by RP-HPLC. Effective parameters such as pH, applying voltage and extraction time were optimized individually. Optimum conditions were found 12, 100 V and 10 min for pH, applying voltage and extraction time, respectively. Figures of merit were calculated under optimum conditions, therefore, linear range and limit of detection (LOD) were obtained 0.5-1000 ng mL^-1 with a good coefficient of determination (R²=0.9901) and 0.05 ng mL^-1, respectively. Last but not least, RSD of determination was found 0.67% which shows a satisfactory repeatability. According to the obtained results, proposed method is a precise, accurate, relatively fast and applicable route to determine TMS concentrations in rinse samples.

Direct immersion single-drop microextraction of semi-volatile organic compounds in environmental samples: A review

Single-drop microextraction (SDME) techniques are efficient approaches to pretreatment of aqueous samples. The main advantage of SDME lies in the miniaturization of the solvent extraction process, minimizing the hazards associated with the use of toxic organic solvents. Thus, SDME techniques are cost-effective, and represent less harm to the environment, subscribing to green analytical chemistry principles. In practice, two main approaches can be used to perform SDME - direct immersion (DI)-SDME and headspace (HS)-SDME. Even though the DI-SDME has been shown to be quite effective for extraction and enrichment of various organic compounds, applications of DI-SDME are normally more suitable for moderately polar and non-polar semi-volatile organic compounds (SVOCs) using organic solvents which are immiscible with water. In this review, we present a historical overview and current advances in DI-SDME, including the common analytical tools which are usually coupled with DI-SDME. The review also focuses on applications concerning SVOCs in environmental samples. Currents trends in DI-SDME and possible future direction of the procedure are discussed.