Determination of adsorbed Mn (II) and Cr (III) ions using hydrogel beads and AAS measurements

Abstract

In this work the hydrogel (Poly acrylic acid) beads used for adsorb Mn (II) and Cr (III) from aqueous solutions. The adsorption capacity of the adsorbents is presented, the time required to reach a maximum capacity of bead (130.62, 123.13) mg/g for Mn (II) and Cr (III) ions respectively was about 24 hr. The initial concentration, temperature, time and pH effect on adsorption process were studied. The experimental data have been analyzed using the Langmuir and Freundlich. The Langmuir isotherm model gave the highest R2 value of (0.9999 and 0.9992) for Mn (II) and Cr (III) ions respectively. The thermodynamic parameters were studied and calculated. First-order and second- order kinetic models were used and it is shown that the experimental data was in reliable compliance with the first- order model with an R2 value of (0.984 and 0.993) for Mn (II) and Cr (III) ions respectively. The process is very efficient, especially for the removal of pollutants in aqueous solutions and more than 95% of study cations were removed by this adsorbent. The concentration of metal ion in the solutions was measured using AAS. The method was linear with an R2 of (0.9992 and 0.9989) for Mn and Cr respectively.