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A spectroscopic and theoretical investigation of interaction mechanisms of tetracycline and polystyrene nanospheres under different conditions
- Wan, Tian, Lu, Songhua, Cheng, Wen, Ren, Jiehui, Wang, Min, Hu, Baowei, Jia, Ziyi, Li, Ying, Sun, Yubing
- Environmental pollution 2019 v.249 pp. 398-405
- Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, adsorbents, adsorption, aqueous solutions, density functional theory, electrostatic interactions, energy, humic acids, hydrophobicity, magnesium, microparticles, nanoplastics, nanospheres, pH, polystyrenes, potassium, sodium, tetracycline
- Interaction mechanisms of tetracycline (TC, as a typical antibiotic) on polystyrene microsphere (PSs, as a typical nanoplastic) were conducted by the batch, spectroscopic and theoretical techniques. The batch results showed that Na+ and K+ had no obvious effects on TC adsorption towards PSs, whereas Mg2+ significantly inhibited TC adsorption at pH > 5.0 due to its induced aggregations of PSs. The maximum TC adsorption capacity of PSs in the presence of humic acid (50.99 mg/g) was higher than that of PSs (44.77 mg/g) at pH 6.0. The highly effective adsorption was attributed to electrostatic attraction, π-π interaction and hydrophobic effect, which was determined by FT-IR and XPS analysis. According to DFT (density functional theory) calculations, the adsorption energy of TC/TC+ on PSs (1.52 eV) was significantly higher than that of negative TC− (0.57 eV), whereas minimum distance of TC on PSs (3.684 Å) was shorter than that of TC− on PSs (3.988 Å). The results of theoretical calculations indicated that TC was more preferably adsorbed on PSs with more stable configuration compared to TC−. These findings indicated that PSs can be used as a promising adsorbent for immobilization and pre-concentration of TC from aqueous solutions.