Batch kinetic modeling of arsenic removal from water by mixed oxide coated sand (mocs).

A new granular media developed by coating of iron and manganese on quartz sand surface proved to be effective for arsenic (III) removal from water. The media has shown alkali resistance. The kinetic and thermodynamic studies data were tested using pseudo-second- order, intraparticle diffusion and Elovich equation models. The rate constants, equilibrium sorption capacity and normalized standard deviations were calculated for all the three models. It was shown that all three models almost accurately predict the sorption capacity with respect to time for whole range of data points. However, sorption kinetic data were better correlated using Elovich equation model based on normalized standard deviation. The Langmuir and Freundlich isotherm equations could be used to describe the partitioning behavior of system at different pH and media size. The results of thermodynamic studies show that the As(III) adsorption on Mixed Oxide Coated Sand (MOCS) was endothermic in nature. Kinetic and isothermal studies data have also been used to obtain thermodynamic parameters of the process.