Adsorption of tetracycline on Fe (hydr)oxides: effects of pH and metal cation (Cu2+, Zn2+ and Al3+) addition in various molar ratios
Journal
Royal Society Open Science
Journal Volume
5
Journal Issue
3
Start Page
171941
Date Issued
2018-03
Date
2018-03
Author(s)
Abstract
Iron (Fe) (hydr)oxides control the mobility and bioavailability of tetracycline (TC) in waters and soils. Adsorption of TC on Fe (hydr)oxides is greatly affected by polyvalent metals; however, impacts of molar metal/TC ratios on TC adsorptive behaviours on Fe (hydr)oxides remain unclear. Results showed that maximum TC adsorption on ferrihydrite and goethite occurred at pH 5-6. Such TC adsorption was generally promoted by the addition of Cu2+, Zn2+ and Al3+. The greatest increase in TC adsorption was found in the system with molar Cu /TC ratio of 3 due to the formation of Fe hydr(oxide) Cu TC ternary complexes. Functional groups on TC that were responsible for the complexation with Cu2+ shifted from phenolic diketone groups at Cu/TC molar ratio < 1 to amide groups at Cu/TC molar ratio >= 1. For the addition of Al3+, the complexation only took place with phenolic diketone groups, resulting in the enhanced TC adsorption at a molar Al/TC ratio of 1. However, TC adsorption decreased for Al/TC molar ratio > 1 as excess Al3+. led to the competitive adsorption with Al/TC complexes. For the Zn2+ addition, no significant correction was found between TC adsorption capacity and molar Zn/TC ratios.
Subjects
tetracycline
Fe (hydr)oxide
metal cations
molar ratio
adsorption
Publisher
The Royal Society Publishing
Type
journal article