Equilibrium and kinetics evaluation of the adsorption of chromium(vi) ions onto uludağ abies sawdust (abies nordmanniana ssp. bornmuelleriana)

The wastewater containing heavy metal ions became one of the most important environmental issues, nowadays. Therefore in this thesis, the potential usage of Uludağ abies (Abies nordmanniana ssp. Bornmuelleriana) sawdust as an adsorbent in removal of Cr(VI), which is a heavy metal ions, Cr(VI), from aqueous solutions by adsorption technique has been evaluated in this thesis. Uludağ abies sawdust has been used as natural without any physical or chemical pretreatment. After being characterized the adsorbent by different techniques, the removal conditions of Cr(VI) ions from wastewaters have been investigated by batch adsorption technique. For this reason the effects of parameters including initial solution pH, contact time, initial Cr(VI) concentration, adsorbent amount and salts have been evaluated on the Cr(VI) adsorption efficiency. The optimum aqueous solution pH was found to be 2.0 and the contact time was 240 min for Cr(VI) removal. The adsorption kinetics have been investigated by pseudo-first order, pseudo-second order and intraparticle diffusion models. In order to clarify the adsorption mechanism the experimental data were fitted to Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models. The maximum adsorption capacity of Uludağ abies sawdust was found to be 15.74 mg/g by using Langmuir isotherm model. The results of the present thesis proved that Uludağ abies sawdust can be used as an effective and low cost adsorbent in removal of Cr(VI) ions from wastewater by adsorption techniques.