摘要
基于重金属污染土壤植物修复过程中产生大量含重金属的生物质收获物,以含重金属芦竹收获物为研究对象,通过在芦竹收获物中添加化学固定材料,研究其热解制备生物炭过程中As,Cd和Pb等重金属的稳定与富集特征。研究结果表明:热解过程中生物质中重金属主要富集在生物炭中,其质量分数及存在形态明显受热解温度、热解时间、固定材料种类及添加量等因素影响;在250℃下添加0.5%(质量分数,下同)的Na OH、热解0.50 h,生物炭产率达到86%;芦竹生物质热解制备生物炭过程中As的稳定适宜条件为在300℃添加2%Na OH,热解2.00 h;Cd的稳定适宜条件为在250℃添加5%Fe Cl3,热解0.50 h;Pb的稳定适宜条件为在400℃添加5%Ca CO3,热解1.00 h;添加Fe Cl3热解得到的生物炭比表面积达到0.31 m2/mg,重金属固定率提高;添加固定材料Na OH后热解制备的生物炭中As主要以残渣态存在,添加Ca CO3,Al2O3和Fe Cl3等固定材料后热解制备的生物炭中As主要以可氧化态存在;添加Na OH,Ca CO3,Al2O3和Fe Cl3等固定材料后热解制备的生物炭中Cd主要以残渣态存在,Pb主要以可氧化态存在。
Considering that a large amounts of biomass harvested containing heavy metals will be produced by phytoremediation for metal contaminated soil, the harvested biomass of giant reed containing heavy metals was selected, and the stability and enrichment characteristics of As, Cd and Pb in the pyrolysis process for biochar were studied by adding chemicals. The results show that the heavy metals in biomass are mainly enriched in biochar, and the amount and speciation of heavy metals in biochar are affected deeply by temperature of pyrolysis, pyrolysis time, the kind and amount of chemicals added. The percentage of biochar arrives at 86% when biomass is pyrolysed for 0.5 h by adding 0.5% NaOH of 250 ℃. The optimized stability conditions for As in biochar is pyrolysed for 2.00 h by adding 2% NaOH at 300 ℃, and for Cd in biochar is pyrolysed for 0.50 h by adding 0.5% FeCl3 at 250 ℃, for Pb in biochar is pyrolysed for 1 h by adding 5% CaCO3 at 400 ℃, respectively. The specific surface area of biochar reaches 0.31 m2/mg by adding FeCl3 and the stability capacity of heavy metals in biochar significantly increases. According to the BCR sequential extraction procedure, the speciation of As in biochar exists mainly in residual form from the pyrolysis by adding NaOH while those of As in biochar exists mainly in oxidizable form by adding CaCO3,Al2O3 and FeCl3. The speciation of Cd in biochar exists mainly in residual form, and that of Pb in biochar exists mainly in oxidizable form with adding stable agents including NaOH, CaCO3, Al2O3 and FeCl3.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2016年第7期2189-2195,共7页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(21577176
41271330)~~
关键词
植物修复
芦竹收获物
热解
重金属
phytoremediation
biomass harvested of giant reed
pyrolysis
heavy metal
