摘要
本研究采用室内模拟实验的方法,考察了生物炭(热解温度200,300,400,500℃)对Pb(Ⅱ)的吸附行为,并以草酸和柠檬酸为代表,探讨有机酸对生物炭吸附Pb(Ⅱ)的影响.结果表明:Langmuir模型较Freundlich模型更适合于对两类生物炭(花生壳生物炭、松木生物炭)吸附Pb(Ⅱ)的数据进行拟合,200℃制备的花生壳生物炭对Pb(Ⅱ)的吸附容量最大;生物炭吸附Pb(Ⅱ)的过程为自发过程,且花生壳生物炭强于松木生物炭,低温生物炭强于高温生物炭;柠檬酸浓度为2.60×10^(-2)mmol/L及草酸浓度为7.65×10^(-2)mmol/L以下时,其在生物炭表面的吸附为Pb(Ⅱ)提供了更多的吸附位点,从而促进了Pb(Ⅱ)吸附;有机酸浓度增大以后,占据生物炭的内部孔隙,竞争重金属吸附位点,从而抑制了Pb(Ⅱ)在生物炭上的吸附.本研究将为系统认识生物炭的环境效应提供重要的基础信息,有助于全面评估有机酸影响下生物炭在环境修复中的功能.
Biochar is a solid product produced by pyrolysis of waste biomass under anaerobic oxygen conditions. Because of its porosity, large specific surface area, rich oxygen-containing functional groups, rich minerals and strong stability, biochar has been widely used in the remediation of heavy metal contaminated soils. The passivation effect of biochar on heavy metals is affected by not only the properties of heavy metals and biochar, but also organic acids secreted from plant rhizosphere in soil. However, the effects of organic acids on biochar-heavy metal interactions have not been studied limitedly. Therefore, in this paper, oxalic acid and citric acid were chosen as organic acids to explore the mechanisim on the adsorption behavior change of Pb(Ⅱ) on biochars (different pyrolysis temperatures at 200, 300, 400and 500℃). Comparing with the Freundlich model, the Langmuir model was more suitable for fitting the adsorption data of Pb(Ⅱ) on two types of biocharsi.e peanut shell biocarsand pine biochars. The peanut shell biocars prepared at 200℃ had maximum adsorption capacityon Pb(Ⅱ). The process of Pb(Ⅱ) adsorption by biocharswas spontaneous, the adsorption stability of peanut shell biocars was stronger than pine biochars, and the adsorption stability decreased as pyrolysis temperature increased. When the concentration of citric acid and oxalic acid was below 2.60×10^-2mmol/L and7.65×10^-2mmol/L respectively, the adsorbed organic acids would provide more binding sites for Pb(Ⅱ), thus promoting the adsorption of Pb(Ⅱ). When the concentration of organic acids increased, the internal pores of biochars may be occupied by the organic acids, which would compet for the binding sites of heavy metals and thereby inhibite the adsorption of Pb(Ⅱ) on biochars. This study will provide important basic information for systematically understanding the environmental effects of biochars, and will help to comprehensively evaluate the function of biochars in environmental remediation in the presence of organic acids.
作者
周丹丹
屈芳舟
吴敏
储刚
吴文卫
ZHOU Dan-dan;QU Fang-zhou;WU Min;CHU Gang;WU Wen-wei(Faculty of Environmental Science and Engineering,Kunming University of Science andTechnology,Kunming 650500,China;Yunnan Institute of Environmental Science,Kunming 650034,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2019年第3期1199-1207,共9页
China Environmental Science
基金
国家自然科学基金资助项目(41703121)
昆明理工大学人才启动项目(KKSY201722006)
云南省重点研发计划资助(2018BC004)
