A potential-responsive ion-pump system based on nickel hexacyanoferrate film for selective extraction of cesium ions

A nickel hexacyanoferrate(NiHCF)film electrode was prepared with NiHCF,conductive carbon black,and polyvinylidene difluoride,which was coated on graphite plate substrate for selective extraction of Cs^(+)ions by using electrochemically switched ion exchange(ESIX)technology.A potential-responsive ionpump system for efficient extraction of Cs+ions was designed,and the effect of wet film thicknesses,charging modes,flow rates,and chamber widths on Cs+ions extraction performance was investigated.In the system,the adsorption capacity and removal percentage of Cs^(+)ions on the NiHCF film electrode reached as high as 147.69 mg·g^(-1)and 92.47%,respectively.Furthermore,the NiHCF film electrode showed high selectivity for Cs^(+)ions and stability.After seven cycles of adsorption/desorption,the desorption percentage could reach about 100%.The excellent Cs^(+)extraction performance should be attributed to the strong driving force produced by the potential-responsive ion-pumping effect in the ESIX process,as well as the low ion transfer resistance of the film electrode which is caused by the special crystal structure of NiHCF.In addition,the NiHCF film electrode was implemented to work together with the bismuth oxybromide(BiOBr)film electrode to accomplish the simultaneous extraction of Cs^(+)and Br^(-).And the adsorption capacity and removal percentage of Br^(-)ions on the BiOBr film electrode reached 69.53 mg·g^(-1)and 77.32%,correspondingly.It is expected that such a potential-responsive ion-pump system based on NiHCF and BiOBr film electrodes could be used for the selective extraction and concentration of Cs^(+)and Br^(-)ions from salt lake brine.

Recovery of lithium using H_(4)Mn_(3.5)Ti_(1.5)O_(12)/reduced graphene oxide/polyacrylamide composite hydrogel from brine by Ads-ESIX process

Powdery Li^(+)-imprinted manganese oxides adsorbent was widely used to the recovery of Li^(+),but there are some difficulties,such as poor stability in acid solution,inconvenience of operation and separation.In this work,a useful hydrogel composite based H_(4)Mn_(3.5)Ti_(1.5)O_(12)/reduced graphene oxide/polyacrylamide(HMTO-rGO/PAM)was fabricated by thermal initiation method with promising stable,conductive and selective properties.The resulting materials were characterized by field emission scanning electron microscope,infrared absorption spectrum,X-ray diffraction,X-ray photoelectron spectroscopy and electrochemical techniques.The recovery of Li^(+)was investigated using HMTO-rGO/PAM from brine by a separated two-stage sorption statically and electrically switched ion exchange desorption process.The adsorption capacity of 51.5 mg·g^(-1)could be achieved with an initial Li^(+)concentration of 200 mg·L^(-1)in pH 10,at 45℃ for 12 h.Li^(+)ions could be quickly desorbed by cyclic voltammetry(CV)in pH 3,0.1 mol·L^(-1)HCl/NH;Cl accompanying the exchange of Li^(+)and H+(NH;)and the transfer of LMTO-rGO/PAM to HMTO-rGO/PAM.