Development, Characterization and Ion Exchange Thermodynamics for a New Crystalline Composite Cation Exchange Material: Application for the Removal of Pb 2+ Ion from a Standard Sample (Rompin Hematite) Z. A. AL-Othman • Mu. Naushad • A. Nilchi Received: 5 February 2011 / Accepted: 26 April 2011 / Published online: 5 May 2011 Ó Springer Science+Business Media, LLC 2011 Abstract A new crystalline organic–inorganic composite cation exchanger polyaniline Sn(IV) molybdate was developed by mixing polyaniline into the inorganic pre- cipitate of Sn(IV) molybdate. This material was charac- terized using Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetry–differential ther- mogravimetry (TGA–DTA), X-ray, scanning electron microscopy (SEM) and elemental analysis studies. Ion- exchange capacity, effect of calcinations (100–500 °C) on ion exchange capacity, pH-titrations, chemical stability, elution and distribution behavior were also carried on this material. On the basis of distribution studies, the material was found to be highly selective for Pb 2? ion and its selectivity was tested by achieving some important binary and ternary separations. In order to demonstrate the prac- tical utility of the material, quantitative separations of Pb 2? from a standard reference material (Rompin Hematite) of lead have been achieved. Thermodynamic parameters viz- entropy change (DS), enthalpy change (DH) and Gibb’s free energy change (DG) were also calculated. Keywords Polyaniline Sn(IV) molybdate  Sorption  Thermodynamic parameter  Pb 2? ion selectivity  Separation  Real sample of Pb 2? 1 Introduction The presence of high level of toxic heavy metals in envi- ronment produces considerable adverse effect not only to the plants and the animals but also to the human being due to their toxicity and non-biodegradability [1, 2]. Waste- waters containing toxic metals (Hg 2? , Pb 2? , Cd 2? , Cu 2? , Fe 3? , etc.) are generated as a byproduct in various indus- tries. Among these toxic heavy metal ions, especially lead ion is very toxic even in low concentration in water. Lead enters in the environment through water, air and soil and finally enters the food chain. Lead can affect almost every organ and system in the body. The main target for lead toxicity is the nervous system, both in adults and children. Lead exposure also causes small increases in blood pres- sure, particularly in middle-aged and older people and can cause anemia. Exposure to high lead levels can severely damage the brain and kidneys in adults or children and ultimately cause death. Hence the removal of Pb 2? ions from water and waste water is important in terms of pro- tection of public health and environment [3–5]. There are many methods for removal of heavy metal ions from aqueous solution viz- ultra filtration, reverse osmosis, phytoextraction, solvent extraction, adsorption and ion exchange. Amongst various processes developed to remove the metal ions, it is observed that at low concentrations, the removal is more effective by ion exchange [6–8]. Organic inorganic composite materials prepared by sol–gel method have attracted a great attention in separation science because they have high selectivity towards these toxic metal ions [9–13]. In the present effort we have reported the detailed study of synthesis, characterization and analytical applications of newly synthesized crystalline composite cation exchanger polyaniline Sn(IV) molybdate. The material was Z. A. AL-Othman  Mu. Naushad (&) Department of Chemistry, College of Science, King Saud University, Building-5, Riyadh, Saudi Arabia e-mail: shad81@rediffmail.com A. Nilchi NSTRI, P.O. Box 11365-8486, Tehran, Iran 123 J Inorg Organomet Polym (2011) 21:547–559 DOI 10.1007/s10904-011-9491-9