Removal of basic dye from water onto pristine and HCl-activated montmorillonite in fixed beds

The removal of a basic dye from water onto pristine montmorillonite and HCl-activated montmorillonites in fixed beds was investigated. Experiments were carried out as a function of liquid flow rate, influent dye concentration, and column length. The adsorption capacity of basic dye onto pristine clay could be largely improved when the clay is activated by HCl. The mathematical models that involve two parameters of standard deviation (σ) and the time (t0) were tested to fit the measured breakthrough curves of basic dye in fixed beds. A macroscopic model developed by Hutchins and kinetic studies were fitted to calculate the adsorption capacity in fixed beds. It is indicated that the predominating step of mass transfer for the adsorption system was diffusion of stagnating liquid-film for pristine clay, but intraparticle diffusion for HCl-activated clay. In addition, the application of the mathematical models is discussed.