Abstract

In this study the removal of Cr (VI) from synthetic wastewater was investigated using Acroptilon repens (Russian Knapweed) fl ower powder under various conditions (pH, contact time and initial concentration of Cr). The capacity of chromium adsorption at equilibrium conditions by this biosorbent was increased by adsorbate concentration. The results also showed that the removal effi ciency of Cr (VI) was increased by increasing the contact time. By increasing the initial concentration of Cr (VI) solution, chromium removal was reduced. The suitability of adsorbents and their constants was tested or evaluated with the Langmuir, Freundlich and Temkin isotherms models. The results indicated that the Freundlich and Langmuir models (R2 > 0.99) gave a better concordance to the adsorption data in comparison with the Temkin equation (R2 = 0.97). The adsorption of Cr (VI) followed the pseudo-second-order kinetics (R2 = 0.991). The study showed that Acroptilon repens fl ower powder can be used as an effective lignocellulosic biomaterial and biosorbent for the removal of Cr (VI) from wastewater.