title: Study on the binding interaction of chromium(VI) with humic acid using UV-vis, fluorescence spectroscopy and molecular modeling.
abstract: In this report, the binding interaction of chromium(VI), as Cr2O7(2-), with humic acid was studied by using UV-visible absorption, fluorescence spectroscopy, and molecular modeling method. The fluorescence spectral data indicated that the binding interaction existed between Cr2O7(2-) and humic acid and the order of magnitude of binding constants were 10(3). The rise in temperature caused a decrease in the values of the binding constant of humic acid with Cr2O7(2-). Thermodynamic analysis presented that multi-intermolecular forces including hydrogen bonding, hydrophobic, and electrostatic forces were involved in the binding process at pH 6.5. The spectral data also indicated that Cr2O7(2-) affected the aromatic ring structures in humic acid. Furthermore, the molecular modeling analysis indicated that a lot of reactive groups and binding cavities in HA played a key role in its binding with Cr2O7(2-).
authors.affiliation: Institute of Applied Chemistry and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China.
authors.forename: Yun-Lan
authors.initials: YL
authors.lastname: Gu
authors.affiliation: Institute of Applied Chemistry and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China.
authors.forename: Ming-Xing
authors.initials: MX
authors.lastname: Yin
authors.affiliation: Institute of Applied Chemistry and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China. Electronic address: hxzhm@126.com.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Zhang
authors.affiliation: Institute of Applied Chemistry and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China.
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Wang
authors.affiliation: Institute of Applied Chemistry and Environmental Engineering, Yancheng Teachers University, Yancheng City, Jiangsu Province 224002, People's Republic of China.
authors.forename: Jing-Hua
authors.initials: JH
authors.lastname: Shi
keywords: Binding mechanism; Chromium(VI); Fluorescence spectroscopy; Humic acid; Molecular modeling