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. [ABSTRACT FROM AUTHOR]