Spouted bed contactor is a hybrid of fixed and fluidized bed contactors, which retains the advantages of each with good hydrodynamic conditions. The aim of the present study is to investigate the performance of a batch conical air spouted vessel for heavy metal removal by strong cation exchange resins (AMBERJET 1200 Na). The effect of various parameters such as type of heavy metal ions (Ni +2 and Pb +2 ), contact time, superficial air velocity and initial heavy metal ion concentration on % heavy metal ion removal has been investigated. It has been found that under optimum conditions 98% and 99% removal of Ni +2 and Pb +2 were achieved respectively. Several kinetic models were used to test the experimental data and to examine the controlling mechanism of the sorption process. The present results of Ni +2 and Pb +2 well fit pseudo second order kinetic model with a high correlation coefficient. Both film diffusion and intra-particle diffusion contribute to the ion exchange process. The present study revealed that spouted bed vessel may provide an effective alternative for conducting ion exchange reactions. ª 2014 Production and hosting by Elsevier B.V. on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/3.0/).

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ab s t r ac tGuava seeds, a byproduct produced during guava juice processing, are currently of no economic value. In the present work two different types of adsorbents have been prepared from raw guava seeds, namely chemically activated guava seed carbon (AGSC) using zinc chloride and chemically modified guava seeds (MGS) through graft co-polymerization reaction. The adsorption capacity of both adsorbents towards Ni(II) has been investigated. It has been found that the equilibrium adsorption capacity is a function of initial pH, contact time, initial nickel(II) concentration, and adsorbent dosage. The optimum pH for both adsorbents was found to be 6. Both Langmuir and Freundlich models best describe the equilibrium experimental data. The maximum adsorption capacities for AGSC and MGS are 18.05 and 32.05 mg/g respectively. The kinetic experimental data were fitted well by the second-order model. The natures of the main functional groups which may be present on raw guava seeds and MGS have been investigated by infrared (IR) studies.