Equilibrium and kinetics studies of methylene blue adsorption on modified Clinoptilolite by MgO nanoparticles

Abstract

Many of dyes generate hazardous, toxic and carcinogenic affects for human and animals. Metylene blue is toxic and very hazardous for environment, so removal of this dye from wastewater is essential for human health. Several methods have been investigated for uptake of dyes from wastewater. The adsorption process is an excellent procedure because it is fast, simple and not expensive. Some economic and effective adsorbents are used for removal of dyes, such as activated carbon [1], fly ash [2] and zeolites [3]. Zeolites are extensively used as adsorbents in environmental systems because of their porous structure, high adsorption capacity, low cost, non-toxicity and abundance in nature [4]. In this research, the MgO-clinoptilolite nano-adsorbent were prepared by co-precipitation method. The performance of these nano adsorbent was investigated in the removal of methylene blue as an cationic dye pollutant from water. 20 wt.% MgO-clinoptilolite has the best performance. The effect of process variables, including pH, temperature (oC) and adsorbate to adsorbent weigh ratio (mgr/gr) on the removal efficiency of dye were investigated by Response Surface Methodology (RSM). At the optimum condition (pH 9.5, temperature of 43 °C, adsorbate to adsorbent weigh ratio of 1.25 mg/g), the maximum removal efficiency was obtained 96 %. Various isotherms were tested to investigate adsorption equilibrium and among of them, Freundlich was the best isotherm. Also, the fractal like integrated kinetic Langmuir model was an appropriate model among several kinetic models.