Study of conducting medium in composite particle electrodes used for defluoridation by electro-adsorption

A composite particle electrode made of zirconium hydroxide and a conducting medium was studied in electro adsorption to remove fluoride. The acetylene black (AB), carbon fiber (CF), graphite powder (GP), and expanded graphite (EG) were selected as conducting medium, and results showed that their percolation threshold were 20%, 40%, 35% and 40% If the weight percent of the 4 media was 10%, 30%, 35%, and 40%, the electrodes have similar conductivity and their specific capacitance were 3.68, 2.37, 2.65, and 2.11 F/g. SEM images revealed that the surface construction morphology of the 4 electrodes were all rough and porous, and they had similar specific surface area, pore diameter, and surface fractal dimension. When these 4 particle electrodes were used as anodes in a three dimensional reactor, the adsorption amounts reached 8.06, 2.72, 5.71, and 4.27 mg/g under the applied voltage of 4 V between counter electrodes. Compared with 0 V, the adsorption amounts had increased 43.4, 18.8, 41.3, and 44.7 %.