The Utilization of Modified Rye Straws as Biosorbents for Cr (VI) Ions

The potential to remove Cr (VI) ion from aqueous solutions using modified rye straws (MRS), through adsorption was investigated in batch experiments. Rye straws were collected from vicinity of Konya, Turkey and modified with various amount of citric acid (CA). The parameter for modification was selected by trying different parameters such as time, temperature and citric acid quantity. The rate of adsorption was studied under a variety of conditions including initial Cr (VI) concentration (1.10-4-4.10-3M), amount of adsorbent (0.05- 0.4 g), pH (1.5 to 7), and contact time (5-240 min). Adsorption of Cr (VI) uptake is in all cases pH-dependent showing a maximum at equilibrium at pH values of 1.5-2.0 for (MRS). The batch sorption kinetics has been tested and the applicability of the Langmuir and Freundlich adsorption isotherms for the present system has been tested at 25°C. The experimental results inferred that adsorption, electrostatic attraction, complexation and chelation are major adsorption mechanisms for binding Cr (VI) ion to the (MRS). Compared to the various other adsorbents reported in the literature, the (MRS) shows very good alternative adsorbent for practical applicability for waste streams and the results indicated that MRS can be employed as a low cost alternative in the removal of Cr (VI) ion from wastewater