Synthesis and characterization of reinforced hybrid porous beads: Application to the adsorption of malachite green in aqueous solution

This study focuses on the preparation by an extrusion-dripping method of sodium alginate (SA)/aluminum-pillared montmorillonite (Al-PILMt)/polyvinyl alcohol (PVA)/calcium carbonate (CaCO3) beads using different percentages of Al-PILMt, PVA and CaCO3. Mechanical and physical characteristics of these reinforced hybrid porous beads (RHPB) were connected to the thermodynamic and kinetic adsorption properties of malachite green (MG). Mechanical properties were investigated using uniaxial compression of single wet bead. The corresponding calculated Young's moduli were found to correlate with the PVA amount which was used in the formulation of the beads. However, these modulus values increased by approximately 70% compared to SA beads taken as references. Beads samples based on PVA and Al-PILMt prove to be more elastic with a better mechanical stability. In contrast, the addition of calcium carbonate in the mixtures leads porous beads PB with a low stiffness less than the RHB. The efficiency of RHPB was evaluated towards the elimination of MG from aqueous solutions. The dye removal, about 8% with SA beads, increased significantly with RHPB (27%) and HPB without PVA (46%). Pseudo first order kinetics with rapid initial adsorption rate and Freundlich equation are respectively used for the description of kinetic and isotherm equilibrium results. Obtained results by the principal component analysis (PCA) method showed the influence of the two main structural variations (i.e. porosity and stiffness) on their adsorption properties. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved..