Studies of the adsorptive decoloration of aqueous solutions by MDFSD

The present study deals with the decoloration of water. Adsorptivity of moderate density fiberboard saw dust (MDFSD) for different dyes has been tested. Continuous as well as batch systems were used to evaluate the adsorptivity of three different dyes (crystal violet, methyl blue and brilliant green). Breakthrough times of the three dyes were compared. Crystal violet was chosen for more detailed studies. The adsorption kinetics and the saturation equilibrium were studied using batch system as a function of the related parameters. Adsorption isotherms were established and compared. Breakthrough plots were obtained beside the three isotherms. The breakthrough times were found as CV > MB > BG. These results were compatible to the adsorptivity estimated from the isotherms. It was found through this study that adsorption of CV followed pseudo-first order kinetics, the adsorption rate constant increases with increasing temperature, adsorbent concentration, MDFSD dose and pH. The adsorption equilibrium was shifted toward higher adsorption capacity by increasing the substrate concentration, temperature and pH. The adsorption data fit Freundlich, Langmuir, but attained a better correlation with the Langmuir model. Langmuir and freundlich constants, activation enthalpy of adsorption and the adsorption thermodynamic parameters were obtained