Arsenic Removal in polluted water by iron intercalated clay

DILJKAN, M.; IRIEL, A.; FERNÁNDEZ CIRELLI, A.; TRINELLI, M.A.; MARCO BROWN, J. L. ; DOS SANTOS AFONSO, M.

San Martín, Buenos Aires

Congreso; The Fifth International Symposium on Environmental Biotechnology and Engineering; 2016

Arsenic (As) is an element widely spread in Argentina. Its consumption for long periods, even in low concentrations, is responsible of illness such as cancer, diabetes, skin pigmentation changes and others. There are emerging and innovative technologies suitable to small scale in rural and urban areas1. Intercalated clays are interesting materials to be used as adsorbents, due to the abundance and low cost of clays that it used as raw material, as well as to the fact of being tunable in terms of properties. Intercalated clays exhibit multi-charged centers, large area and high interlayer space. Intercalated clays have been previously characterized and used in studies of adsorption of organic compounds and toxic elements2. In view of this background, the aim of the present work is to evaluate the use of iron polyoxocations intercalated clays to remove As (V) from drinking water.Iron intercalated clays (FeMt) were prepared following a method previously reported3 from a montmorillonite (Mt) and a Fe(NO3)3 solution. Mt and FeMt were characterized by XRD and SAXS and N2 adsorption-desorption isotherms were obtained. Adsorption of As(V) on Mt and FeMt was studied in batch systems. As(V) determination was carried out by ICP-OES (Perking Elmer, Optima 2000). Mt is not able to remove As(V) while the As(V) adsorption capacity by FeMt was studied at pH 4, 6 and 8 and the mayor capacity was found for pH 4. In addition, arsenic adsorption at pH 8 was studied at ionic strength values of 0.001, 0.01 and 0.025 M (KNO3). An As(V) adsorption increase was found for higher values of ionic strength. Kinetics study was carried out at pH 8 and experimental data were adjusted by pseudo first (PFO) and second (PSO) order, intraparticle diffusion (IDM) and mixed surface reaction and diffusion-controlled kinetic (MSR/DCK) models. About 99% of the initial arsenic was removed in 30 min for an As(V) initial concentration of 1 mgL-1. Arsenic adsorption isotherm at pH 8 and ionic strength of 0.001M (KNO3) was obtained and the experimental data was adjusted by Langmuir and Freundlich