Preparation Of Ion-Surface Imprinted CNTs/PANI/PSS Composite Films And Their ESIX Performance

Electrochemically switched ion exchange?ESIX?is realized by adjusting the redox states of the electroactive film to achieve the separation of the target ions and the regeneration of the film electrode.In this method,the main driving force is the potential,which can effectively avoid secondary pollution produced by the traditional ion exchange regeneration,but the selectivity is relatively low in the separation and recovery of rare earth ions and heavy metal ions in waste water.However,the ion imprinted technology,as a novel ion imprinting technology,has wide application prospect in the separation and recovery of rare earth ions and heavy metal ions owing to possessing these advantages,such as the uniform binding sites,high selectivity and exchange capacity,fast recognition kinetics,high ion exchange capacity and excellent chemical stability.In this paper,the Y³⁺-imprinted sulfonated multi-walled carbon nanotubes/polyaniline/poly?styrenesulfonic acid?composite film(Y³⁺-s MWCNT/PANI/PSS)was synthesized by ion surface-imprinted technology,and the ESIX method was applied to achieved the separation and recovery low concentration of Y³⁺.That the group of-SO₃H on the surface of sMWCNT can bind the target Y³⁺ by chelating;the doping of PSS can provide acidic environment for PANI to increase its electrical activity.The structure and morphology of the composite film were characterized by means of Fourier transform infrared?FTIR?,X-ray diffraction?XRD?and scanning electron microscopy?SEM?.The ion exchange performance was detected by electrochemical quartz crystal microbalance?EQCM?.The results showed that Y³⁺-sMWCNT/PANI/PSS composite film had high ion exchange capacity and good selectivity.And the film can identify the Y³⁺ in the solution quickly and accurately,for the imprinted cavities on the surface of s MWCNT perfectly match the Y³⁺ spatial structure.The ion exchange capacity of Y³⁺ was 209 mg/g and equilibrium time was 20 s.In addition,it exhibited good selectivity for Y³⁺ when competing with other rare earth ions and symbiotic ions in the mixed solution,and showed good stability.The novel ion surface-inprinted composite film can be used for the efficient separation and recovery of low concentration Y³⁺ in waste water.In order to separate heavy metal Pb²⁺ ions,the electroactive Pb²⁺-MWCNTs-OH/PANI/PSS composite film was prepared successfully on the basis of the above experiment using Pb²⁺ as the template ion,polyaniline?PANI?as the polymer matrix and hydroxylated carbon nanotubes?MWCNTs-OH?as imprinting substrate,especially,Pb²⁺ ions were eluted by applying constant positive potential to form imprinted cavities.The structures of MWCNTs-OH and imprinted film were characterized by Fourier transform infrared?FT-IR?and X-ray diffraction?XRD?.The separation performance of the film for Pb²⁺ ion was studied by electrochemical quartz crystal microbalance?EQCM?and atomic absorption spectrophotometer?AAS?.The results showed that Pb²⁺-MWCNTs-OH/PANI/PSS composite film had high ion exchange capacity and excellent selectivity for Pb²⁺.And the maximum ion exchange capacity of composite film for Pb²⁺ was 359 mg/g and the separation factor of Pb²⁺/Zn²⁺ reached 418.74 at the presence of other heavy metals ions(Cd²⁺,Zn²⁺,Co²⁺,Ni²⁺).Besides,the film exhibited outstanding cycle stability and rapid adsorption/desorption properties.This novel ion-surface imprinted composite film can be used for the efficient separation and recovery of Pb²⁺ in waste water.