A Preliminary Study on Remediation of Heavy Metal Contaminated Soil Using Natural Bentonite
|School||South China University of Technology|
|Keywords||Na-modified bentonite (white 600 mesh) Contaminative soil Chinese cabbage Pb Cd|
To study the remediation capacity of the clay minerals in the contaminated water and the soil, four kinds of clay minerals were selected as experimental material. We researched the capacity of them using to absorb heavy metals in the contaminative water, and the adsorption experiment was done in the same temperature. at the same time, We studied the changing rules of renovating the contaminative soil with Cd and Pb in system, by the artificial method, using the Chinese cabbage as indicator plants.The results are as follows:(1)The four kinds of clay minerals: Na-modified bentonite (white 600 mesh), Na-modified bentonite (500-type sallow), bentonite (100 sallow) and sepiolite, have the same strong adsorption ability for Pb2+ of wastewater , the absorptivity of they are up to 99.5%; Na-modified bentonite (white 600 mesh) has the strongest adsorption ability for Cd2+ of wastewater.(2)The Qmaxof Na-modified bentonite (white 600 mesh) for Cd2 + is 51.2 mg / kg, for Pb2+ is about 200mg/kg. So it’s possible for using Na-modified bentonite to reduce the heavy metals mobility in the soil, so as to reduce the possibility harm.(3)With the same liquor, when the pH = 6.32, the adsorptive amount of Na-modified bentonite (white 600 mesh) for Cd2+ and Pb2+ was much lower than the pH = 8.32.(4)Compared to Pb, the cabbages had preferential adsorption to Cd,which is 5-10 times more than Pb. The cabbages which were grown in the soil without clay minerals had higher heavy metal content than which were grown in the soil added some Na-modified bentonite.(5)Both the water-solubility Cd and the the hydronium commutative state of Cd in the high or low contaminative soil were descend after one month., So as the valid Cd. The effect of adding Na-modified bentonite (white 600 mesh) and planting Chinese cabbages is better than only planting Chinese cabbages. the water-solubility Pb reduced while the the hydronium commutative state of Pb increased in the high contaminative soil, which made for the valid Pb reduced in the high contaminative soil and increased in the low contaminative soil.