中文摘要：

利用固定床热解实验装置在不同热解温度（300~700℃）下制备了3种生物炭[杨树枝炭（PBC）、水葫芦炭（WHC）和玉米秸秆炭（CSC）],以南京市铅锌银矿区周边的菜园土为对象,研究了生物炭种类、热解温度和生物炭添加量对土壤重金属（Pb和Zn）吸附特性的影响,并结合生物炭的孔隙度、XRD和FTIR等分析,初步探讨了生物炭对土壤重金属的吸附机制.结果表明,生物炭的添加均不同程度地降低了土壤中Zn和Pb的浸出含量,水葫芦炭对土壤重金属的吸附效果最佳,在热解温度为500℃和生物炭添加量为5%的条件下,水葫芦炭对土壤中Zn和Pb的吸附率分别为21.83%和44.57%,相应的单位吸附量分别为227.65μg·g^-1和363.76μg·g^-1.随着热解温度的升高,生物炭对土壤中Zn和Pb的吸附率逐渐增大,且在热解温度为500℃和700℃下制备的水葫芦炭对土壤中Zn和Pb的吸附能力相差不大,这表明中等温度热解有利于水葫芦炭形成较好的理化特性.随着生物炭添加量的增加,水葫芦炭对土壤中Zn和Pb的吸附率逐渐增大,但单位吸附量却逐渐减小,当水葫芦炭添加量为10%时,其对土壤中Pb的吸附率可达93.93%.结合生物炭的理化结构和土壤重金属吸附实验的结果,可以推测离子交换和络合作用是水葫芦炭修复重金属污染土壤的主要作用机制.

英文摘要：

Three types of biochars,poplar branch biochar（ PBC）,water hyacinth biochar（ WHC）,and corn straw biochar（ CSC）,were prepared in a fixed-bed pyrolyzer at different pyrolysis temperatures（ 300-700℃）. The effects of biochar species,pyrolysis temperature,and biochar addition on adsorption characteristics of typical heavy metals（ HMs） such as Pb and Zn in vegetable soil（ collected from a lead-zinc-silver mining area,Nanjing,China） were investigated. The adsorption mechanism of biochar on HMs was discussed based on the analyses of pore structure,XRD,and FTIR of biochars. WHC biochar showed the best adsorption ability at the same experimental conditions with adsorption efficiencies on Zn and Pb of 21. 83% and 44. 57%,respectively. The relative adsorption capacities of Zn and Pb were 227. 65 μg·g^-1and 363. 76 μg·g^-1at the pyrolysis temperature of 500℃ and biochar addition of 5%.The adsorption efficiency of biochar on HMs in soil increased gradually with increasing pyrolysis temperature. WHC biochars prepared at 500℃ and 700℃ had similar adsorption capacities on Zn and Pb in soil indicating that the moderate pyrolysis may be a good choice for WHC with better physicochemical properties. Increasing the amount of WHC addition benefits the adsorption efficiency of HMs in soil,but does not increase the adsorption capacity. The adsorption efficiency of Pb in soil reaches 93. 93% by adding 10% of WHC into the soil sample. The combined analyses based on the physicochemical properties of biochar and the results of soil HMs adsorption experiments suggest that ion exchange and complexation are prevailing mechanisms of the remediation of HM-contaminated soil by WHC biochars.