ENVR 256 |
| The removal of heavy metals from contaminated industrial wastewaters using various adsorbents represents an eco-friendly purification method. The removal of chromium (VI) from aqueous solutions onto Erythrina variegata orientalis leaf powder is carried out extensively in batch operations. The maximum removal of 95.7% is achieved at pH=3 for the equilibrium agitation time of 180 min. The biosorption of Cr (VI) increases with an increase in adsorbent dosage from 10 g/L to 50 g/L and decrease in adsorbent size from 150 µm to 45 µm. The biosorption is decreased from 99.1(0.446 mg/g) to 53.3% (1.917 mg/g) with an increase in chromium initial concentration (C0) from 22.5 to 180 mg/L. The chromium removal is decreased from 1.754 to 1.267 mg/g with an increase in volume of aqueous solution from 25 to 200 ml. The biosorption is decreased from 1.767 to 1.414 mg/g with an increase in temperature from 283 to 333 K. Langmuir and Redlich-Peterson isotherm models represent the data very well compared to the Freundlich isotherm model. The biosorption data follows second-order kinetics with a rate constant of 0.104 g/mg-min for 60 g/L of 45 µm adsorbent size. The negative value of ΔH reflects the exothermic nature and the negative value of ΔS shows a reversible process. The process is tending towards irreversibility as ΔS is a approaching positive value with an increase in C0. The change in ΔG from negative to positive indicates the feasibility of biosorption at lower temperatures. 50 g/L of 45 µm size adsorbent removes 94.7% (1.705 mg/g) of chromium from 50 ml of (C0 = 90 mg/L) aqueous solution. |
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Advances in Adsorption Processes for Drinking Water Treatment and Sourcewater Protection
6:00 PM-8:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster
Division of Environmental Chemistry |