Optimization of Soil Washing Conditions using Chitosan as Chelating Agent for the Removal of Chromium from Contaminated Soil by Response Surface Method

Author : Lorio, Cyrielle Tibayan
Major Adviser : Detras, Monet Concepcion M. 
Committee Members : Migo, Veronica P.; Laurio, Michael Vincent O.
Year : 2017
Month : June
Type : Thesis
Degree: BS
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This study focused on the application of soil washing techniques using chitosan as the chelating agent in the remediation of the chromium contaminated soil of land from Sta. Cruz, Zambales. Soil washing was employed using chitosan solution at various pH levels (1, 5), concentration (0.5 g/L, 2.5 g/L), and soil loading (0.04 g/mL, 0.2 g/L) to determine the effect of each factors on the removal of chromium from the contaminated soil. Results showed that the amount of chromium removed from the soil ranged from 0.15 to 55.32 mg Cr/kg soil, with the highest removal observed at pH 1.0, chitosan concentration of 2.5 g/L, and soil loading of 0.04 g/mL. Based on ANOVA (α = 0.05), only pH was found to have a significant effect on the amount of chromium removed from the contaminated soil. Decreasing the pH of the chitosan solution increases the amount of chromium removed. One factor design was then employed to find the optimum pH. Optimum condition was found to be at pH 0.5 while chitosan solution concentration (0.5 g/L) and soil loading (0.2 g/mL) were chosen based on practical approach. At the optimum condition, actual chromium removal of 130.75 mg Cr/kg soil was attained. The actual value deviates from the predicted value with a 3.22% error. Preliminary cost for the batch soil washing for chromium removal from the soil was estimated to be 733.98 Php/kg soil or 5.61 Php/mg Cr, which may be considered as acceptable since it accounts for remediation of the soil and potential recovery of metals in soil.

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