摘要
随着核工业的发展,大量放射性污染物被排放到环境中,严重威胁着人类健康.生物炭材料作为一种可再生资源,具有丰富的孔隙结构和独特的表面化学性质,因此被广泛地应用于环境中污染物的去除.本文分别用煅烧处理后的咖啡渣(CG)和硝酸氧化后的咖啡渣(CG-AO)作为生物炭吸附剂,研究了它们在模拟含铀废水中对U(Ⅵ)的去除性能,探究了溶液pH、反应时间、U(Ⅵ)的初始浓度、反应温度等因素对溶液中U(Ⅵ)去除率的影响,并通过X射线光电子能谱(XPS)光谱分析了相应的吸附机理.结果表明, pH对U(Ⅵ)在CG和CG-AO上的吸附效果影响显著,在近中性p H范围内表现出最佳的吸附效果;吸附反应能很快达到平衡,准二级动力学方程能够很好地拟合吸附动力学过程; Langmuir模型能较好地描述CG-AO对U(Ⅵ)的等温吸附过程,吸附容量与温度呈正相关;室温下改性得到生物炭材料对U(Ⅵ)的饱和吸附量约为251.71 mg g^(-1),几乎是未改性前生物炭的3倍(80.93 mg g^(-1)).基于XPS光谱分析发现, CG-AO对U(Ⅵ)的吸附机理可能是通过羧基与U(Ⅵ)形成表面配合物(O=C–O)_2UO_2,而CG则可能是通过羧基与水的协同作用与U(Ⅵ)形成表面配合物O=C–OUO_2(OH).
With the rapid development of nuclear industry,radioactive wastes have been directly/indirectly released into the natural environment,threatening the health of human being and ecological balance.As one of the renewable materials,biochar has attracted increasing attention and been extensively applied to eliminate pollutants from aqueous solution,owing to its abundant pore structures and unique chemical properties.In this study,we used the carbonized coffee ground(CG)and acid-oxidized coffee ground(CG-AO)to remove U(VI)from solutions to evaluate their sorption performances.The sorption of U(VI)was investigated under various conditions(e.g.,contact time,pH,initial U(VI)concentration and temperature).The results showed that the sorption process was strongly influenced by pH.The thermodynamic parameters derived from sorption isotherms revealed that the sorption of U(VI)on CG-AO was a spontaneous and endothermic process.The maximum sorption capacity of U(VI)on CG-AO was calculated to be 251.71 mg g_1 from Langmuir model at 7^298 K and pH 5.0,which was almost three times relative to the untreated CG(80.93 mg g_1).Combined with the X-ray photoelectron spectroscopy(XPS)analysis,the removal of U(VI)on CG-AO was mainly attributed to the formation of(O=C-O)2UO2,while the removal ofU(VI)on CG was mainly via a combined effect of carboxyl and H2O molecules,resulting in the coordination of O=C-OUO2(OH).
作者
宋爽
顾鹏程
陈中山
王祥学
张瑞
文涛
Shuang Song;Pengcheng Gu;Zhongshan Chen;Xiangxue Wang;Rui Zhang;Tao Wen(College of Environmental Science and Engineering,North China Electric Power University,Beijing 102206,China;Department of Environmental Science and Engineering,North China Electric Power University,Baoding 071003,China;National Center for Nanoscience and Technology,Beijing 100190,China)
出处
《中国科学：化学》
CAS
CSCD
北大核心
2019年第1期155-164,共10页
SCIENTIA SINICA Chimica
基金
国家自然科学基金(编号:21607042
21577032
21707033)
中央高校基本科研业务费专项资金(编号:2018ZD11
2017MS045)资助项目
关键词
U(VI)
生物炭
光谱分析
吸附机理
U(VI)
biochar
spectroscopy analyses
sorption performance
