Arsenic removal from water using a new generation adsorbent: Titanium dioxide coated with magnetic nanoparticles

Arsenic in drinking water resources is a global health problem. Of the As species commonly found in groundwater, As(III) is generally more mobile and toxic than As(V). In this work, commercial TiO₂ was modified with magnetic nanoparticles (TiO₂-MNp), in order to develop an adsorbent which can combine oxidation and adsorption properties and which can be readily separated from water using a magnetic field. The adsorption capacity of TiO₂-MNp and arsenic removal mechanism of this novel material was investigated through kinetic and equilibrium experiments and their corresponding mathematical models. It was found that the arsenic adsorption mechanism on MNp-FeMn involves chemisorption and intraparticle diffusion. The maximal adsorption capacity, q_max of TiO₂ for As(III) (21 mg/g) was improved after modification with magnetic nanoparticles (31 mg/g), while q_max for As(V) were 16 and 20 mg/g, respectively. The high oxidation and adsorption capacity of TiO₂-MNp and magnetic properties, suggest this material is a highly promising adsorbent for treatment of arsenic contaminated groundwater.