ZHANG Jie1,2, Khan M.G. Mostofa1,2, Nicola Senesi3, Giorgio S. Senesi4, LI Siliang1,2,5
（1.Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China;
2.Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China;
3.Dip.to di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari "Aldo Moro", Via G. Amendola 165/A, Bari, Italy 70126;
4.CNR - Istituto per la Scienza e Tecnologia dei Plasmi (ISTP) - sede di Bari Via Amendola, 122/D Bari, Italy 70126; 5.Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China)
Abstract：Pharmaceutical antibiotic (PA) residues are pervasive in soil and water environments; current biological or photochemical degradation methods are difficult to effectively remove PA residues due to constraints on removal efficiency and possible carcinogenic by-products. Up to now, it is not clear about the adsorption/complexation mechanism of metal ions with PA. In this work, two commonly used PAs-levofloxacin hydrochloride (LH) and tamsulosin hydrochloride (TH) were removed from aqueous solution using FeCl3; it was found that Fe3+ in the form of Fe-PA precipitate (Fe-PAp) separated PA from aqueous solution at pH=7.5~8.5. About 90.3% and 87.5% of LH and TH were removed in the form of Fe-PAp after five successive precipitations from the corresponding aqueous solutions with FeCl3, respectively. The IR characteristics of original LH and TH and Fe-PAp were also studied comparatively, and it was found that: 1) the main IR peaks of LH and TH exhibited: 3433 and 3329 cm-1 (carboxylic acids OH and NH2), 1676 cm-1 (-COO-), 1467 cm-1 (aliphatic C-H) and 1022 cm-1 (-S=O), 2) the intensity of the aforementioned IR peaks in Fe-PAp decreased or disappeared completely. The chemical bonding analysis shows that during the formation of Fe-PAp, electrons are transferred from various PA functional groups to the unpaired d orbitals of Fe3+, forming a π-d electron bonding system. FeCl3 has a wide range of practical applications: 1) as an efficient and promising inorganic adsorbent for the removal of PA from water, which in turn may open new fields in the large-scale separation of organic pollutants from domestic and industrial wastewater; 2) Fe-PAp formation indicates that metal-organic complexes can be stabilized in alkaline soils and water for a long time, explaining the long-term stabilization/sequestration mechanism of Fe-DOM complexes in the environment.
Key words：pharmaceutical antibiotics (PA); levofloxacin hydrochloride; tamsulosin hydrochloride; ferric chloride
EARTH AND ENVIRONMENT Vol.51, No.1, Tot No.351, 2023, Page 117
