Ion exchange kinetics of some heavy metals from aqueous solutions onto poly (acrylic acid-acrylonitrile) potassium titanate

Abstract

Heavy metals released by a number of industrial processes are major pollutants. Ground, industrial and even treated wastewaters, heavy metals can be extremely toxic as they damage nerves, liver, kidney and bones. So, our work was concerned to prepare composite inorganic-organic absorbers which represent a group of inorganic ion exchangers modified using binding organic materials. Polyacrylonitrile (PAN) has been used as a universal binding polymer for a number of inorganic ion exchangers. Acrylic acid-acrylonitrile (AA-AN) comonomer mixture was prepared at the optimum copolymerization process and potassium titanate was synthesized by adding 200 ml of 2.2 M TiCl4, and 800 ml of 2.8 M KOH were prepared and mixed with constant stirring to the 1000 ml of AA-AN. These composites have been tested for separation of various contaminants from aqueous solutions. Their high selectivity and sorption efficiency are advantageous for treatment of various industrial waste waters. The kinetic of lead (Pb2+), cadmium (Cd2+) and zinc (Zn2+) ions on the prepared material were studied by applying the Nernest-plank equation. The rate of exchange is controlled by particle diffusion mechanism. The physical thermodynamic parameters such as activation energy and entropy of activation have been evaluated. The selectivity order towards the ions was found: Pb (II) > Cd (II) > Zn (II). Key words: Adsorption, polyacrylic acid-acrylonitrile, heavy metals, potassium titanate, equilibrium.