@article {XU2019111375,
	title = {Co-adsorption of ciprofloxacin and Cu(II) onto titanate nanotubes: Speciation variation and metal-organic complexation},
	journal = {Journal of Molecular Liquids},
	volume = {292},
	year = {2019},
	pages = {111375},
	abstract = {Titanate nanotubes (TNTs) have been reported to show good adsorption performance for heavy metals, but researches on organic contaminants adsorption by TNTs are limited. In this study, co-adsorption of a heavy metal (Cu) and an emerging organic contaminant (ciprofloxacin, CIP) by TNTs was investigated in binary systems. TNTs could simultaneously remove the two contaminants, with a high adsorption capacity of 234.5 μmol/g for Cu(II) and 237.0 μmol/g for CIP at pH 4 in the binary system. pH greatly affected adsorption due to speciation variation of the contaminants and surface charge change of TNTs. Cu(II)-CIP complexes dominated adsorption capacity and mechanism. Adsorption of CIP was promoted by high concentration of Cu(II) at pH 3{\textendash}8 due to formation of abundant Cu(CIP{\textpm})2+, while inhibited by low concentration of Cu(II) because of competitive adsorption. The adsorption affinity of CIP species to TNTs was ranked as: Cu(CIP{\textpm})2+ \> CIP+ \> CIP{\textpm} \> Cu(CIP{\textpm})2+ \> Cu(CIP-{\textperiodcentered}CIP{\textpm})+ \> CIP-. In comparison, the co-existence of CIP slightly affected Cu(II) adsorption considering the strong affinity of Cu2+ to TNTs. X-ray photoelectron spectrometer (XPS) and Fourier transform infrared spectroscopy (FTIR) results further confirmed the formation of Cu(II)-CIP complexes through {\textendash}NH2Cu/{\textendash}COOCu linkages. This work not only proposed a feasible technology for co-removal of heavy metals and organics from water, but also presented insight into interaction mechanisms of different contaminants with nanomaterials during adsorption.},
	keywords = {Adsorption, Complexation, Emerging organic contaminant, Heavy metal, Interaction mechanism, Titanate nanotubes},
	issn = {0167-7322},
	doi = {http://doi.org/10.1016/j.molliq.2019.111375},
	url = {http://www.sciencedirect.com/science/article/pii/S0167732219307901},
	author = {Xuming Xu and Yuxin Liu and Ting Wang and Ji, Haodong and Long Chen and Si Li and Liu, Wen}
}