Preparation of a novel environmentally friendly hydrophobic deep eutectic solvent ChCl‐THY and its application in removal of hexavalent chromium from aqueous solution

Abstract

A liquid–liquid extraction methodology was developed for the removal of Cr(VI) from contaminated water using a novel green hydrophobic deep eutectic solvent (DES) as an efficient sole extracting agent. The hydrophobic DES was obtained by mixing choline chloride and thymol in 1:4 molar ratio at 70°C for 10 min and was denoted as ChCl‐THY(1:4). The ChCl‐THY(1:4) works efficiently for removal of high (20 mg/L) and low (500 µg/L) concentration of Cr(VI) from artificially contaminated natural water with >95% extraction efficiency (E%) at optimized reaction conditions (pH 2–6, 40°C). The DES was characterized by 1H NMR and FTIR spectroscopy, and the data suggest that interaction occurs between Cl− ion of choline chloride and H atoms of thymol molecules. Physicochemical properties such as density, melting point, moisture, and solubility were studied and discussed. Herein, no sharp melting point was observed for ChCl‐THY(1:4) in DSC curve. DES was regenerated using 0.1 M NaOH as stripping agent, and 50%–60% extraction efficiency could be attained in the next cycle. A plausible mechanism of interaction between Cr(VI) species and DES was also explored with the help of FTIR spectroscopy. Practitioner Points A novel hydrophobic DES (ChCl‐THY) is prepared by mixing choline chloride and thymol at 1:4 molar ratio. ChCl‐THY(1:4) is employed for the first time as sole extracting agent to remove the Cr(VI) from contaminated aqueous solution. >95% extraction efficiency was achieved by ChCl‐THY(1:4) in natural water conditions at µg/L and mg/L level of contamination. Both the component used to prepare the DES are naturally abundant; hence, DES is not toxic for biota. The element present in natural water did not show any interference with extraction of Cr(VI).

Nanohybrid of Thymol and 2D Simonkolleite Enhances Inhibition of Bacterial Growth, Biofilm Formation, and Free Radicals

“…The signal is diminished at 709 cm −1 for the nanohybrid spectrum and could suggest possible partial intercalation [ 39 ]. In this type of reaction, chlorine reacts with phenol or compounds containing phenolic groups such as thymol and can then support the displacement of the C-C aromatic ring band [ 40 ].…”