Testing Thymol-Based DES for the Elimination of 11 Textile Dyes from Water

Abstract

Textile industries release dangerous wastewater that contain dyes into the environment. Due to their toxic, carcinogenic and mutagenic nature, they must be removed before the discharge. Liquid–liquid extraction has proven to be an efficient method for the removal of these dyes. As extractants, deep eutectic solvents (DESs) have shown excellent results in recent years, as well as presenting several green properties. Therefore, four different hydrophobic DESs based on natural components were prepared thymol:decanoic acid (T:D (1:1)), thymol:DL-menthol (T:M (1:1)), thymol:DL-menthol (T:M (1:2)) and thymol:coumarin (T:C (2:1)) for the extraction of Malachite Green (MG), Brilliant Blue G (BBG), Acid Yellow 73 (AY73), Reactive Red 29 (RR29), Acid Blue 113 (AB113), Reactive Black 5 (RB5), Remazol Brilliant Blue (RBB), Direct Yellow 27 (DY27), Acid Blue 80 (AB80), Direct Blue 15 (DB15) and Acid Violet 43 (AV43) dyes from water. The operational parameters of the liquid–liquid extraction were selected in order to save time and materials, resulting in 30 min of stirring, 15 min of centrifugation and an aqueous:organic ratio of 5:1. In these conditions, the highest values of extraction obtained were 99% for MG, 89% for BBG and 94% for AY73. Based on these results, the influence of the aqueous:organic phase ratio and the number of necessary stages to achieve water decolorization was studied.

Thymol as Starting Material for the Development of a Biobased Material with Enhanced Antimicrobial Activity: Synthesis, Characterization, and Potential Application

“…1 H NMR (300 MHz, CDCl 3 ) δ H (d, J = 6.9 Hz, H-9 and H-10), 2.26 (s, H-7), 3.16 (m, H-8), 4.72 (s, H-11), 6.57 (s, H-5), 6.72 (d, J = 7.8 Hz, H-2), and 7.07 (d, J = 7.8 Hz, H-1). 13 (16), 107 (11), 91 (16), 77 (5), and 65 (4).…”

“…Thymol can also be used for biological applications due to its strong bactericidal activity [1]. Recently, some studies have reported on several applications of thymol (isolated or combined in composites), such as food packaging [3], agricultural products [4], industrial [5] and pharmacokinetic areas [6], and drug delivery with encapsulation [7], and the studies aimed to overcome its hydrophobicity, volatility, and other limitations that could narrow its application. Its antimicrobial activity is directly related to the functional groups present in the molecule, especially the hydroxyl group at the aromatic ring [8].…”

Origin of structural and dynamic heterogeneity in thymol and coumarin-based hydrophobic deep eutectic solvents as revealed by molecular dynamics

“…Villar et al utilized thymol and coumarin-based HDESs for the removal of harmful textile dyes from water. 69 Ozak et al employed thymol and coumarin-based HDESs for Sudan dye extraction from samples of spices. 70 The thymol : coumarin (1 : 1) HDES exhibited better performance as compared to conventional solvents, with advantages like a fast processing and an environmentally friendly method.…”

“…71 A fair amount of experimental work exists showing the employment of thymol and coumarinbased HDESs in multiple applications. [68][69][70][71] However, theoretical studies focusing on the formulation mechanism by highlighting various key interactions and the dynamic behavior of thymol and coumarin-based HDESs are not available in the literature.…”

“…We have specifically chosen 1 : 1 and 2 : 1 thymol : coumarin molar ratios considering the experimental evidence of the HDES formation following the sustainability criteria 68 and various applications of the HDES having these two molar ratios. [68][69][70][71] By analyzing the real-space pair correlations and X-ray/neutron scattering structure functions (S(q)s), we identify the origin of the observed prepeak and depict the presence of intermediate-range ordering or nanoscale heterogeneity within thymol and coumarin-based HDESs. In these HDESs, hydrogen bonding interactions mainly guide the structural arrangement, and by computing hydrogen bond dynamics, we have deciphered the relaxation of hydrogen bonds and classified the nature of the hydrogen bonds as weak or strong.…”