| Summary: | 碩士 === 國立中興大學 === 土壤環境科學系 === 91 === Agricultural wastes in Taiwan are mass-produced and need befitting attention to avoid pollution. Some of agricultural wastes could be carbonized and activated to increase surface area and pore to adsorb more pollutants. The purpose of this study was to evaluate the feasibility of carbonized agricultural wastes as adsorbents of heavy metals to remedy heavy metals polluted paddy soil.
The test soils were collected from six heavy metals polluted paddy field in Changhua. Rice hulls, peanut hulls and bagasse chosen as test agricultural wastes were carbonized and CO2 activated to be activated carbons. The ability of heavy metals adsorption of carbonized agriculture wastes were compared with market activated carbon and un-active rice hulls. The constant “K’’ and the maximum adsorbed amounts of adsorbate “b” calculated from Langmuir adsorption isotherms indicate the order of adsorption efficiency of the heavy metals were Pb > Cu > Zn > Cd > Cr > Ni. The adsorbed amounts of heavy metals by carbonized agriculture wastes increased with increasing concentration of heavy metals. The adsorbed amounts of heavy metals by carbonized peanut hulls were the highest followed by carbonized bagasses. The adsorption abilities of carbonized agriculture wastes on EDTA-extracable heavy metals from soils were tested in batch and leaching experiments. The adsorption efficiency of carbonized bagasses was the best followed by carbonized peanut hulls and carbonized rice hulls. In general, the adsorbed amounts of heavy metals by market activated carbon and un-active rice hulls were less than carbonized agriculture wastes, because the un-active rice hulls were not activated to increase surface area. The low adsorption efficiency of both un-active rice hulls and market activated carbon was attributed to their small pore size resulting in more resistant to mass transport even the surface area was higher than the others, and to their low basic function groups on the surface.
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