%0 Journal Article
%J Journal of Molecular Liquids
%D 2019
%T Co-adsorption of ciprofloxacin and Cu(II) onto titanate nanotubes: Speciation variation and metal-organic complexation
%A Xuming Xu
%A Yuxin Liu
%A Ting Wang
%A Ji, Haodong
%A Long Chen
%A Si Li
%A Liu, Wen
%K Adsorption
%K Complexation
%K Emerging organic contaminant
%K Heavy metal
%K Interaction mechanism
%K Titanate nanotubes
%X 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 3–8 due to formation of abundant Cu(CIP±)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±)2+ > CIP+ > CIP± > Cu(CIP±)2+ > Cu(CIP−·CIP±)+ > 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 –NH2Cu/–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.
%B Journal of Molecular Liquids
%V 292
%P 111375
%G eng
%U http://www.sciencedirect.com/science/article/pii/S0167732219307901
%R http://doi.org/10.1016/j.molliq.2019.111375