Studies on the removal of Neutral Red on sand from aqueous solution and its kinetic behavior

Neutral Red (NR) dye in aqueous solution present as a pollutant material in textile waste water was removed by adsorption on sand at 298 K. Local sand sample which was used as an adsorbent in this work was initially characterized for its textural properties including surface area, mean pore radius and total pore volume. These properties were examined from the low-temperature adsorption of nitrogen on sand samples at 77 K. Later on the conditions of maximum adsorption of the dye on characterized sand sample were optimized. It was seen that under optimized conditions, up to 85% dye could be removed from solution onto the sand surface. The adsorption data were fitted to Freundlich and Lagergen equation for the calculation of various adsorption parameters. The Freundlich constants n and A were determined to be 0.997 and 0.2001 mol/g, respectively. The rate constant for adsorption of Neutral Red on sand sample as calculated by using the Lagergen equation was estimated to be 3.85 min^-1. The application of Boyd's equation revealed that particle diffusion was not operative in this case and thus does not control the kinetics of dye adsorption on sand. The adsorption behavior of the dye was also investigated in terms of added cations and anions. It was found that the dye adsorption decreased in the presence of chloride, sodium and copper ions.