Biosorption isotherm and kinetic studies for the removal of Pb (II) and Fe (II) ions from synthetic waste water using unmodified Dennettia tripetala

Various heavy metals have been released into the waters, causing serious pollution of water resources and endangering human health. Therefore, it is very important to study the removal of heavy metals from water. In this work, the adsorption of heavy metal ions including Pb(II), Cu(II), and Fe(II), onto Dennettia tripetala from aqueous solutions was investigated in mixed systems. The batch adsorption experiment for heavy metal ions on Dennettia tripetala mixed system was studied at different conditions including contact time, initial concentration, initial pH and adsorbent dosage. The results indicated that the adsorption kinetics followed the pseudo-first order model base on R2 for Fe(II) which is 0.907, and pseudo-second order for Pb(II) with R2 = 0.70 respectively. Hence the freundlich isotherm model is the best fit for Fe(II) with R2 = 0.979 and for the Pb(II), it fits Temkin model with R2 = 0.930. The final removal efficiencies and maximum adsorption capacity followed the order of Pb(II) > Cu(II) > Fe(II) at room temperature. The bio-sorption of heavy metals determined by the pH of the solution and the adsorbent dose, was found that the initial pH of 7 was optimal for the removal of Pb(II) and Fe(II), which was different from the optimum initial pH below or above 7. The results demonstrated that the electrostatic interaction between the surface of the Dennettia tripetala and heavy metal ions played an important role in the adsorption of heavy metal ions. In addition, compared to other researches, the results in mixed system showed that the adsorption of Cu(II), Pb(II) and Fe(II) was promoted since none of the metal co-exist with one another.