Arsenic [As(III) and As(V)] adsorption on aluminum substituted cobalt ferrite (Co-Al-Fe) ternary metal oxide adsorbent is reported by means of qualitative and quantitative spectroscopy tools. IR and Raman active signals were observed around 810-920 cm band indicate different As-OH and As-O stretching vibrations on to the adsorbent. The adsorption behavior of arsenic (III and V) onto these adsorbents is studied as a function of contact time, different concentrations, and pH conditions. The kinetics study on adsorption were performed to understand nature of adsorption which supports the Pseudo Second Order (PSO) model. The adsorption isotherms study indicates Freundlich type of adsorption. The maximum adsorption capacity of Co-Al-Fe adsorbent is observed around 130 and 76 mg g for As(III) and As(V) systems, respectively. Detailed XPS study of As 3d, Fe 2p, Co 2p, and O 1s spectra has been reported in explaining the redox behavior and ligand exchange reactions in supporting arsenic adsorption mechanism.

The adsorption of arsenic [arsenite (As(III)) and arsenate (As(V))] onto aluminum substituted nickel ferrite (Ni-Al-Fe) which is a ternary metal oxide nano adsorbent is evaluated. Qualitative and quantitative studies were performed to understand the adsorption phenomenon. The qualitative studies for both adsorbent and arsenic adsorbed samples were evaluated using FT-IR, Raman and XPS techniques and the quantitative studies were carried out using ICP-OES technique. The results reveal that the maximum adsorption capacities of Ni-Al-Fe adsorbent are around 114 and 103 mg g À1 for As(III) and As(V) species in 100 ppm arsenic equilibrium concentration (C e ) systems. Also, at low initial concentrations (100 and 500 ppb) a better adsorption phenomenon (i.e. WHO guidelines limit of 10 ppb) for the As(V) species onto the Ni-Al-Fe adsorbent was observed. In addition the kinetics of adsorption, and effect of concentration and pH on the adsorption phenomena have been detailed. † Electronic supplementary information (ESI) available: Information about adsorbent synthesis, Raman spectra (individual peak identication), quantitative study related plots and tables and arsenic stretching vibrations from literature. See

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