Adsorption of direct red 12 B by biogas residual slurry: Equilibrium and rate processes Original Research Article

The rate of adsorption of Direct red 12 B, a direct dye, on biogas residual slurry (BRS) has been studied. The parameters studied include dye concentration, particle size, temperature and pH. The rate controlling step is mainly intraparticle diffusion, although a small boundary layer resistance is expressed. Almost total removal of dye occurred at pH 2•3. Adsorption of dye conforms with the Freundlich isotherm.