Methyl violet dye adsorption onto clinoptilolite (Natural Zeolite): Isotherm and kinetic study

Abstract

The dyes and pigments have poisonous and mutagenic effect on humans and animals. In this study, the use of Bigadic clinoptilolite (natural zeolite) as an adsorbent for removal of methyl violet dye from solutions was investigated. The dye adsorption experiments were carried out in batch mode as a function of pH (3-9), temperature (30-50 degrees C), ionic strength (0-0.1 M NaCl), clinoptilolite calcination temperature (0-200 degrees C), particle size (0-45;180-425 mu m) and solid-to-solution ratio (0.1-1.5g150 mL). The dye adsorption capacity of the clinoptilolite mineral increased with high solution pH, high temperature, high salt concentration, low particle size and low solid-to-solution ratio. Clinoptilolite mineral provided higher adsorption capacity at calcination temperature of 50 degrees C. The equilibrium adsorption data fitted to the Langmuir isotherm rather than Freundlich model. The kinetic data could be explained by the pseudo second order model. Also, the kinetic data fitted to the intra particle diffusion model and this indicated that pore diffusion was rate controlling step in the applied batch process. Maximum adsorption capacity of the clinoptilolite mineral was calculated as 75.25 mg/g at pH 9.