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| Adsorption of Tetracycline and Tylosin on MnO2 Coated Carbon Nanotubes |
| Received:November 07, 2014 |
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| KeyWord:carbon nanotubes;manganese dioxide;tetracycline;tylosin;adsorption |
| Author Name | Affiliation | E-mail | | DENG Li-ping | Ministry of Education Key Laboratory for Integrated Regulation and Resources Development on Shallow Lakes, Hohai University, Nanjing 210098, China
College of Environment, Hohai University, Nanjing 210098, China | | | JI Liang-liang | Ministry of Education Key Laboratory for Integrated Regulation and Resources Development on Shallow Lakes, Hohai University, Nanjing 210098, China
College of Environment, Hohai University, Nanjing 210098, China | jill@hhu.edu.cn | | BAI Zhao-tun | Ministry of Education Key Laboratory for Integrated Regulation and Resources Development on Shallow Lakes, Hohai University, Nanjing 210098, China
College of Environment, Hohai University, Nanjing 210098, China | |
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| Abstract: |
| Carbon nanotubes have strong adsorption affinities to organic pollutants in water due to their large and hydrophobic surface areas. However, carbon nanotubes are easy to flocculate. Here we studied the adsorption behaviors of two typical pharmaceutical antibiotics(tetracycline and tylosin) on multi-walled carbon nanotubes coated with manganese dioxide(MnO2/MWNT). MnO2/MWNT showed extraordinarily high adsorption affinity to both antibiotics. Adsorption of tetracycline and tylosin by MnO2/MWNT enhanced 5~8 times, compared to MWNT alone. This enhanced adsorption of tetracycline and tylosin by MnO2/MWNT was due to strong interactions(π-π electron-donor-acceptor interactions, cation-π bonding and Lewis acid-base interaction) with the graphene surface of MnO2/MWNT. Similar pH-dependent adsorption was observed in tetracycline and tylosin. When pH was increased from 3 to 11, adsorption coefficient decreased significantly. Increasing pH facilitated deprotonation of charged amino group and protonated enol groups, hence weakening the cation-π bonding, π-π EDA interaction and Lewis acid-base interaction between antibiotics and MnO2/MWNT. The presence of humic acids prominently suppressed tylosin adsorption on MnO2/MWNT, but only slightly affected tetracycline adsorption on MnO2/MWNT. This was because relatively large humic acid could not effectively compete adsorption sites with relatively small tetracycline on MnO2/MWNT. |
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