Özet:

In this study, removal of chromium(VI) from aqueous solution by adsorption onto agricultural waste (modified sunflower head waste) was investigated. Batch studies were conducted and effect of initial solution pH, initial concentration, adsorbent dosage, temperature, and contact time on the removal of Cr(VI) was investigated. Cr(VI) was determined by UV spectrophotometry. The maximum removal was obtained at the initial pH of 1 for initial concentration 150 mg/L, at 25 oC and 240 rpm. Adsorption yield increased with the increasing adsorbent dosage and temperature. Langmuir and Freundlich isotherm models were applied to data. Pseudo first order and pseudo second order kinetic models were applied to fit kinetic data. Thermodynamics parameters were also determined. The positive values of ΔH° change indicated that adsorption is endothermic. Negative values of ∆G° showed adsorption process is spontaneous. The positive ΔS° values indicated that the randomness increase. Adsorbent capacity was obtained as 7.35 mg/g.

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