Recovery of rare earth by electro-sorption with sodium diphenylamine sulfonate modified activated carbon electrode

Electro-sorption has been used for water purification and desalination, but little research on the recovery of rare earth element (REE) in aqueous solution. In this work, sodium diphenylamine sulfonate (SDAS) modified the activated carbon (AC) on carbon felt (CF) is used to recovery the La(III), Nd(III) and Ce(III) ions by electro-sorption. Moreover, this electrode can be refreshed under the reversal voltage without any other chemical reagent. After 500 min of reaction, the adsorption capacity of La(III) ions reaches nearly 600 mg g−1, which remains stable in three cycles. Due to the synergistic effect of chemical and physical absorption, the electro-sorption of La(III) ions on SDAS/AC-CF electrode follows Langmuir isotherm, the pseudo-first-order and pseudo-second-order models. Moreover, the adsorption capacities of Nd(III) and Ce(III) ions after nearly 180 min of reaction are 275 mg g−1 and higher than 366 mg g−1, respectively. Herein, white flocculent La(OH)3, purple flake-type purple Nd(OH)3 and brownish yellow spherical CeO2 are obtained after electro-sorption. This method is simple without the pollution of other chemical reagents. Therefore, it has revealed potential application value in the recovery of REE from wastewater.