Fabrication Of Layered Double Hydroxides Hybrid Film And Its ESIX Performance For DS~- Ions

The anionic surfactants that be called"monosodium glutamate in industry"find wide application in nuclear industry,dyes industry,power generation and other fields,and a large amount of wastewater containing organic anionic pollutants are discharged into water bodies in nature,causing serious harm for environment.At present,the common methods of removing anionic surfactants usually produced the secondary pollution and the operation process is complicated.Thus,it is particularly urgent to find an efficient and environmentally friendly method.Electrochemically switched ion exchange technology（ESIX）combined ion exchange with electrochemical technology to eliminate the secondary pollution.The core of ESIX technology is the EIXMs on the surface of the substrate which can conduct electricity and ions simultaneously.In this paper,PPy/r GO/Ni Co-LDH and HKUST-1（C）@LDH hybrid film electrodes were fabricated for the removal of dodecyl sulfonate ions（DS^-ions）in wastewater treatment.An electroactive ion exchange hybrid film of polypyrrole/reduced graphene oxide/Ni Co-layered double hydroxide（PPy/r GO/Ni Co-LDH）with three-dimensional（3D）“sand rose”flower-like structure was fabricated by a two-step electrodeposition method.Ni Co-LDH nanosheets were electrodeposited on the surface of polypyrrole/graphene oxide（PPy/GO）conducting substrate for the removal of dodecyl sulfonate ions（DS^-ions）with low concentrations.Herein,the electroreduction of GO to r GO enhanced the electron conductivity and the unique structure of PPy/r GO/Ni Co-LDH hybrid film ensured the fast diffusion of electrons as well as ions.The cyclic voltammetry（CV）and electrochemical impedance spectrum（EIS）were performed to characterize the electrochemical performance of hybrid film and the effects of the applied electrode potential,initial concentration of DS^-ions and p H of the simulated wastewater on the uptake kinetics of DS^-ions were investigated.As a result,the coexisting anions had no obvious effect on the adsorption of DS^-ions and the removal percentage of DS^-ions reached 92.31%in a 10 mg·L^-1 DS^-solution with an electrode potential of 0.8 V.Especially,in the p H ranging from 5.0 to 9.0,the DS^-ions were efficiently removed.In addition,the double-driven ion exchange mechanism coupling electric double-layer（EDL）effect of r GO and pseudo capacitance effect of PPy to remove DS^-ions was proposed based on the X-ray photoelectron spectroscopy（XPS）and CV analyses.It is expected that such a novel PPy/r GO/Ni Co-LDH hybrid electroactive ion-exchange film separation technology based on the double-driven mechanism could be a potential technique for wastewater.To improve the adsorption capacity of hybrid film to DS^-ions,HKUST-1（C）@LDH hybrid film electrode was prepared on copper network using the electrochemical deposition method,and a new pulsed discharge technique was used to reduce the influence of co-existing anions in solution on the process of DS^-ions removal.The electrochemical properties of HKUST-1（C）@LDH hybrid film were studied by CV and EIS experiments.The effects of pulse discharge technology and different initial concentrations on DS^-ions removal were also investigated.The experimental results show that the HKUST-1（C）@LDH hybrid film can remove DS^-ions more efficiently.When the initial concentration of the DS^-ions is 200 mg·L^-1,the adsorption capacity of the hybrid film to DS^-ions is as high as 733.84 mg·g^-1.After 1000 times of cyclic scanning,the charge capacity of hybrid film can still reach 87.94%of the original charge capacity.In summary,the HKUST-1（C）@LDH hybrid film has good stability,selective separation performance and high adsorption capacity for DS^-ions.The hybrid film with the novel pulsed discharge technology based on ESIX technology can achieve efficient and selective separation of DS^-ions.