摘要
利用红外(FTIR)光谱、Boehm滴定、比表面积及微孔分析等方法对300℃、400℃、500℃、600℃下制备的水稻秸秆生物炭进行表征,分别记录为RC300、RC400、RC500和RC600,同时研究了4种生物炭在不同平衡时间、pH值、浓度下对Pb(Ⅱ)的吸附特征.结果表明,随着热解温度的升高,生物炭表面含氧官能团的数目下降,芳香化程度升高,微孔结构逐渐发育,比表面积逐渐增大.4种生物炭对Pb(Ⅱ)的吸附反应过程满足准二级动力学方程,相关系数R2大于0.9947.随着溶液初始pH值的升高,生物炭的吸附量增加,最佳吸附pH值RC300和RC400为3.5,RC500和RC600分别为6.5和6.0.在25℃时,4种生物炭对Pb(Ⅱ)的吸附容量为RC300>RC400>RC500>RC600,表明在300—600℃范围内,低温条件下制备的生物炭对重金属离子有更强的吸附能力.利用Langmuir方程和Freundlich方程拟合了4种生物炭对Pb(Ⅱ)的等温吸附数据,结果显示RC300和RC400符合Langmuir方程,而RC500和RC600更符合Freundlich方程.
Four types of biochar derived from rice straw generated at different pyrolysis temperatures（300 ℃—600 ℃,referred as RC300—RC600） were characterized and investigated for Pb（Ⅱ） removal from aqueous solution.The biochar characteristics were studied using BET surface area analyzer,FTIR and Boehm titration.The results showed that the number of surface oxygen-containing groups decreased while the degree of aromatase and specific surface area of biochars gradually increased with the increasing pyrolysis temperature.The adsorption behavior of biochars under different time,pH and concentration of adsorbate were also evaluated.The results indicated that pseudo-second-order kinetics model（R20.9947） could well characterize the sorption processes.Pb（Ⅱ） adsorption by biochar increased significantly with increasing solution pH.The optimum solution pH for RC300 and RC400 was 3.5,whereas for RC500 and RC600 it was 6.5 and 6.0.Biochars with low pyrolysis temperatures showed greater sorption capacity.Sorption isotherms varied from Langmuir to Freundlich with increasing pyrolysis temperature.While RC300 and RC400 could be described well by Langmuir model,the adsorption data of RC500 and RC600 fitted the Freundlich model better.
出处
《环境化学》
CAS
CSCD
北大核心
2011年第11期1851-1857,共7页
Environmental Chemistry
基金
中国科学院知识创新工程重要方向项目(KZCX2-YW-Q02-02)
侨办科研基金项目(08QZR04)资助
