摘要
以玉米秸秆为原料,在350℃和700℃热解温度下分别制备了两种生物炭(BC350和BC700),并对其理化性质进行了表征。在700℃下制备的生物炭芳构化程度更高,疏水性更强,比表面积更大,孔结构发育更加完全。研究Cd(Ⅱ)在两种生物炭上的吸附发现,Two-site Langmuir吸附等温模型比One-site Langmuir吸附等温模型能更好描述Cd(Ⅱ)在生物炭表面的吸附。BC700对Cd(Ⅱ)的吸附容量大于BC350,解吸率远小于BC350,吸附效果更好;离子交换和阳离子-π作用两种吸附机理同时存在并共同作用,前者分别占BC350和BC700总吸附容量的13.7%和1.1%,后者分别占86.3%和98.9%,阳离子-π作用是最主要的吸附机理。红外光谱FTIR分析表明,生物炭表面的含氧官能团和π共轭芳香结构分别提供不同机理的吸附位点。由于具有更多的离子交换位点,BC350对Cd(Ⅱ)吸附受pH影响较BC700更大。
Biochar is a novel porous carbonous material derived from pyrolysis of biomass in the partial or total absence of oxygen.In the present study,two biochars were generated from corn straw at pyrolysis temperatures of 350 ℃ and 700 ℃（referred as BC350 and BC700）,and their structural characteristics were analyzed.The two biochars were investigated for their capacity for Cd（Ⅱ）adsorption from aqueous solution.The degree of aromatic structure,hydrophobicity,pore volume,specific surface area,and porosity of biochars were found higher for BC700.The adsorption of Cd（Ⅱ）onto biochar surface was better described by Two-site Langmuir than by One-site Langmuir adsorption isotherm,suggesting the involvement of multiple adsorption processes.Both ion exchange adsorption and cation-π interaction were proposed for the adsorption of Cd（Ⅱ）on biochar.Ion exchange mechanism accounted for 13.7% for BC350 and 1.1% for BC700 of total adsorption capacity,respectively;while the corresponding proportion of cation-π interaction was 86.3% and 98.9%,indicating the leading role of cation-π interaction in Cd（Ⅱ）adsorption.The FTIR spectrograms showed different adsorption sites of aromatic-π structures（for cation-π interaction）and oxygen-containing groups（for ion exchange adsorption）in biochars.The BC700 showed better adsorption performance than BC350 with greater adsorption capacity and lower desorption rate.BC350 was affected by solution pH by a greater extent as compared to BC700,due to the greater proportion of ion exchange adsorption sites.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2012年第11期2277-2283,共7页
Journal of Agro-Environment Science
基金
国家大学生创新性实验计划(101005534)
中央高校基本科研业务费专项基金
日本Asia Pacific Network on Global Change项目(RUSD2010-02NMY(C)-Sun)
关键词
生物炭
镉
吸附
离子交换
阳离子-π作用
biochar
Cd（Ⅱ）
adsorption
ion exchange adsorption
cation-π interaction
