Biochars From Different Pyrolytic Temperature Amending Lead and Cadmium Contaminated Soil
DING Wenchuan, ZHU Qingxiang, ZENG Xiaolan, WU Dan, TIAN Xiumei
College of Urban Construction and Environmental Engineering; Three Gorges Reservoir Area's Ecology and Environment Key Laboratory of Ministry of Education, Chongqing University, Chongqing 400045, China
Abstract：Biochar from biomass pyrolysis has received much attention recently due to its strong affinity for organic pollutants and heavy metals. Previous studies have revealed potential applications of biochar in the contaminated soil remediation. However, the knowledge of pyrolysis temperature effects on biochar as a soil amendment remains lacking. In this paper, three biochars produced at 300℃, 500℃ and 700℃ were added into Lead (Pb) and Cadmium (Cd) contained soil, variations of these two metals were analyzed before and after 60 days incubation. The results show that soil pH value is increased by 0.35—0.86 units after biochars addition and incubation. Acid extractable form contents of Pb and Cd are reduced, whereas the residual form contents are increased. The reducing bio-availability of target heavy metals by different biochar amendments is in the following order: 700℃>500℃>300℃. With the same amount of biochar addition, Pb residual form contents in the combined polluted soil are increased by 50.60%—72.79% from the single polluted soil, and Cd acid extractable form contents in the combined polluted soil are increased by 7.53%—12.99% from the single polluted soil. Pyrolytic temperature affects characteristics of biochar surface structure and mechanism of heavy metal sorption on biochar, and then affects the states of lead and Cadmium in soils.