Electrosorptive defluorination on modified activated carbon fiber with TiO2-coating
负载TiO2的活性炭纤维改性电极电吸附除氟

A modified activated carbon fiber electrode(TiO2/ACF) was prepared by coating TiO2 gel on ACF surface.Then the surface characteristics of the new electrode were analyzed with scanning electron microscopy(SEM),X-ray diffraction spectrometer(XRD) and nitrogen adsorption-desorption isotherm method.The results showed that the modified electrode had coarse surface,decreased specific surface area(BET) and total pore volume,while both the meso-pore volume and the average pore diameter increased.The XRD patterns of the TiO2/ACF electrode indicated that both anatase structure and rutile structure were observed on its surface.Moreover,it’s obvious that the adsorption capacity of the TiO2/ACF electrode can be enhanced under external electric field when it was employed to remove fluoride ions in NaF solutions.Such adsorption capacity can also increase with the increase of the voltage and initial fluoride ion concentration,but the removal rate for fluoride ions displayed an opposite trend under the effect of initial fluoride ion concentration.The electrosorption capacity of 1.03 mg/g was achieved under applied voltage of 2 V for the TiO2/ACF electrode,being 40% higher than its adsorption capacity without external electric field.The change in pH values of NaF solution has a direct influence on the species of different fluoride ions in these solutions and hydroxyl groups on the TiO2/ACF electrode surface,and then induces a variation of electrosorption capacity of the modified electrode.In addition,as the TiO2/ACF electrode was employed to treat the NaF solutions with fluoride ions concentration of 4 mg/L,electrosorption capacity was 1.32 mg/g at the following operation parameters: voltage of 2 V,neutral pH and duration of 12 h.