Assessment of utilization natural and H2SO4 modified oak sawdust in removal of heavy metal ions from aqueous solutions

In this study, the potential usage of natural and H2SO4 modified oak (Quercus L.) sawdust as an adsorbent in removal of heavy metal ions from water and wastewater by adsorption method has been investigated. For this purpose, after being modified the oak sawdust with H2SO4, both natural (NOS) and modified adsorbent (MOS) were characterized by different techniques such as FTIR, Boehm titration, pHpzc and moisture content determination.In order to determine the heavy metal ions to be examined for removal conditions, the effect of initial solution pH was investigated primarily on the adsorption yield. By considering the obtained results, it was decided to investigate the adsorption conditions of Cd (II) ions at pH 4.0 and Cr (VI) ions at pH 2.5 on NOS and MOS. The experimental parameters such as contact time, initial adsorbate concentration, adsorbent amount and salt effect were investigated in detail for the optimization of the experimental conditions on the adsorption of Cd (II) and Cr (VI) ions on NOS and MOS. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were evaluated in order to clarify the adsorption mechanism and the adsorption kinetics wereassessed by applying the pseudo-first order, pseudo-second order and intraparticle diffusion models to the experimental data. From the results, it was seen that the pseudo-second order kinetic model is suitable for describing the adsorption rates of Cd(II) and Cr(VI) ions on both NOS and MOS. On the other hand it was found that the adsorption data of heavy metal ions are compatible with both the Langmuir and Freundlich isotherm models. The maximum Cd(II) ve Cr(VI) adsorption capacities of NOS were obtained as 47.62 and 48.07 mg g-1 respectively, while the maximum Cd(II) ve Cr(VI) adsorption capacities of MOS were found as 64.52 and 100.0 mg g-1, respectively. As a result, it has been concluded that both natural and H2SO4 modified oak sawdust can be used as an effective and low cost adsorbents for the removal of Cd(II) and Cr(VI) ions from water and wastewater.