Granular inorgano-organo pillared clays (GIOCs): Preparation by wet granulation, characterization and application to the removal of a Basic dye (BY28) from aqueous solutions

The aim of the study was to prepare resistant and spherical inorgano-organo pillared clays (GIOCs) granules for wastewater treatment using a new and simple method named high-shear wet granulation. To optimize the preparation method, the effects of the main process parameters, such as binder concentration, liquid to solid ratio and impeller speed on granule properties (size distribution, friability and disintegration tests) were investigated. Experimental results showed that the granulation of inorgano-organo pillared clays (PIOCs) with industrial Silicone is significantly influenced by the binder concentration, the liquid to solid ratio (H %) and the impeller speed (N). A modification of these parameters can greatly alter the characteristics of the granules. The impact of wet granulation on the kinetics and adsorption capacities of GIOCs was estimated using Basic Yellow 28 as model pollutant. Kinetic studies reveals that BY 28 adsorbed faster on PIOCs (k(1) = 7.40 x 10(-2) min(-1)) than on granular forms. Results best fitted the pseudo-first-order kinetic model. It was also found that the adsorption kinetic is directly related to the surface diffusion of prepared GIOCs. The adsorption equilibrium data were analyzed by the Langmuir and Freundlich models using non-linear regression. The best fit to the data was obtained with the Langmuir isotherm. The highest adsorption capacities (Q(max) = 514 mg/g; pH 6) for GIOCs were obtained for the finest forms (300-400 mu m). (C) 2010 Elsevier B.V. All rights reserved.