Adsorption of Acid Dyes from Wastewater on Saudi Bentonite Clay

摘要

Wastewater contains different types of pollutants in varying amount and concentrations. Among these, presence of dyes is of major concern for wastewater treatment. The main aim of this study is to determine equilibrium and kinetic parameters necessary to design a batch adsorber for the adsorption of acid dye 25 by Saudi bentonite clay. The maximum capacity of the bentonite clay for removing the acid dye 25 from wastewater was 12.7 mg g~(-1). The equilibrium parameters for the Langmuir and Freundlich isotherms characterizing the acid dye 25 adsorption were determined at 20, 40, 60 and 75℃. The external mass transfer coefficient characterizing the resistance of the hydrodynamic boundary layer, kf, was found from the initial adsorption data but achieved only limited success. Intra-particle diffusion is a major rate-controlling step in the rate of acid dye 25 removal from aqueous solutions.