Dispersive liquid–liquid extraction of Cr(III) by using choline chloride-thymol deep eutectic solvent and its application for chromium speciation analysis

• Published in: Microchemical journal Vol. 202; p. 110841
• Main Authors: Sapyen, Wannida, Jirattisak, Julalak, Bhawawet, Nakara, Praphairaksit, Narong, Imyim, Apichat
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2024
• Subjects: Chlorine chloride; Chromium; Deep eutectic solvents; ICP-OES; Speciation; Thymol; Chromium; Thymol; Deep eutectic solvents; Speciation; ICP-OES; Chlorine chloride
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2024.110841

[Display omitted] •An ultrafast LLE of Cr(III) by choline chloride-thymol deep eutectic solvent.•Extraction efficiencies of Cr(III) exceeded 95% under the optimized conditions.•Reusable deep eutectic solvent up to five cycles through stripping process.•Successful speciation analysis of Cr demonstrated in real water samples.•The method was fully validated and ready to use for environmental monitoring. This work utilized dispersive liquid–liquid extraction as a non-chromatographic separation technique for chromium speciation employing choline chloride-thymol hydrophobic deep eutectic solvent (DES) coupled with inductively coupled plasma optical emission spectroscopy (ICP-OES). The successful separation of chromium species was achieved with the use of a complexing agent, triethanolamine, which facilitated the migration of Cr(III) from the aqueous phase to the DES phase. Optimal conditions for Cr(III) extraction were determined, including a vortex time of 1 min, pH 9.0, triethanolamine concentration of 0.5 mM, and an aqueous-to-extractant volume ratio of 10. These conditions resulted in the extraction efficiency exceeding 95 %. Similarly, stripping of the extracted Cr(III) was accomplished with 90 % efficiency using 0.2 M nitric acid and a contact time of 12 min at room temperature. The consistently high extraction and stripping efficiencies (80–100 %) throughout the five consecutive cycles via this approach indicate the sustainability and ability to reuse choline chloride-thymol DES. The application of the proposed method was also demonstrated through the analysis of various samples with excellent accuracy and precision.