Enhanced Arsenite Removal Using Bifunctional Electroactive Filter Hybridized with La(OH)_(3)

A bifunctional electroactive filter was rationally fabricated for simultaneous oxidation and sequestration of toxic trivalent arsentic As(Ⅲ).A novel nanoscale La(OH)_(3) modified electrochemical carbon nanotube(CNT)network filter was prepared by a facile electrodeposition strategy.The As(Ⅲ)decontamination kinetics and adsorption capacity were both found to increase with the flow rate(1.5-6.0 mL/min)and the applied voltage(0-2.5 V).The CNT filter hybridized with La(OH)_(3)(CNT-La(OH)_(3))has demonstrated the ultra-high adsorption capacity of 750.2 mg/g for As(Ⅲ),which is ascribed to the combined role of sufficient adsorption sites,flow-through filtration and electric field.XPS analysis revealed that the As(Ⅲ)decontamination mechanism involved a two-step adsorption-oxidation process.The formation of inner-sphere La-O-As complexes,ligand exchange and electro-adsorption are all parts of the As(Ⅲ)adsorption process.The adsorbed neutrally-charged As(Ⅲ)was further oxidized to negatively-charged As(V)when aided by an electric field,which could be effectively sequestrated by La(OH)_(3).The CNT-La(OH)_(3) filter shows high stability under alkaline conditions and can be regenerated with dilute NaOH solution.In this study,all experiment results have demonstrated a promising and effective CNT-La(OH)_(3) electrochemical filter for As(Ⅲ)pollution minimization.