Selective adsorption mechanisms of iodinated trihalomethanes onto thiol-functionalized HKUST-1s in a mixed solute

• Published in: Journal of environmental management 2022-08, Vol.315, p.115099-115099, Article 115099
• Main Authors: Induvesa, Phacharapol, Ratanatawanate, Chalita, Wongrueng, Aunnop, Punyapalakul, Patiparn
• Format: Article
• Language: English
• Subjects: HKUST-1; Iodinated DBPs; Iodinated trihalomethane; Selective adsorption mechanism; Thiol functionalization
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.115099

The selective adsorption mechanisms involved in the competitive adsorption of five iodinated trihalomethanes (I-THMs) onto dithiolglycol and (3-mercaptopropyl)-trimethoxy functionalized HKUST-1 (HK-SH and HK-MPTS, respectively) were investigated by single- and mixed-batch adsorption. HK-SH had the highest adsorption rates and capacities for the five I-THMs, followed by HK-MPTS and pristine HKUST-1, even though the porosity and surface area decreased after modification. The primary adsorptive mechanism of HK-SH consists of ion-dipole interactions of I-THMs with the protonated hydroxyl and thiol groups at the metal (Cu) node, which is supported by Lewis acid-base reactions via Cu–Cu complex and π−π interactions. In a mixed solute, bromodiiodomethane, which was the most hydrophobic and had the smallest molecular size, exhibited the most competitive adsorption on HK-SH. In contrast, the selective adsorption of I-THMs onto HK-MPTS was affected by their log Kow values, causing hydrophobic partitioning onto the alkyl chain of the mercaptopropyl group. Iodinated haloforms tend to achieve a higher adsorption rate and capacity than chlorinated and brominated haloforms via hydrophobic partitioning. Moreover, dithiolglycol grafted onto HK-SH can better promote the excellent selective adsorption performance of iodoacetamide than dichloroiodomethane and iodoacetic acid in both single- and mixed-solute solutions due to hydrogen bonding via the –NH2 group of diiodoacetamide. •Dithiolglycol-HKUST-1 exhibited the highest adsorption rate and capacity of I-THMs.•The ion-dipole interaction of I-THMs at –OH and –SH at the Cu node is dominant.•The hydrophobicity and small size of the I-THMs enhance competitive adsorption.•I-Haloform was adsorbed better than Cl, Br-haloform via hydrophobic partitioning.•IAcAm exhibited higher competitive adsorption than DCIM and IAA.