Fe(Ⅱ)/阳离子掺杂针铁矿矿物系统对2-NP的还原转化性能研究  

A study of the reductive transformation properties of the mineral systems of Fe( Ⅱ)/cation-doped goethite for 2-NP

作　　者：杜可清[1] 吴宏海[1] 朱慧琳[1] 魏西鹏 管玉峰[1] 蓝冰燕[1] DU Ke-qing WU Hong-hai ZHU Hui-lin WEI Xi-peng GUAN Yu-feng LAN Bing-yan(School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China)

机构地区：[1]华南师范大学化学与环境学院,中国广州510006

出　　处：《岩石矿物学杂志》2016年第6期1075-1084,共10页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目(41372050)~~

摘　　要：制备了不同阳离子掺杂改性的针铁矿,并采用XRD、红外、热重差热分析以及TEM等手段对其进行了表征,结果显示,掺入Mn^(2+)、Cr^(3+)、Al^(3+)后并未明显改变α-FeOOH的晶体结构类型,说明部分阳离子掺杂进入α-FeOOH晶格,从而分别形成因Fe^(3+)被Mn^(2+)、Cr^(3+)、Al^(3+)部分取代的固溶体;红外分析也得到类似结果;热重和差热分析以及TEM观察结果均表明几种金属阳离子没有形成氧化物相,可以确定这些离子已经进入针铁矿的晶格;紫外-可见漫反射光谱分析发现Mn^(2+)、Cr^(3+)掺杂者的能带隙较之纯相针铁矿的稍小,依次为2.18 e V和2.24 e V;而Al^(3+)掺杂者的能带隙与纯相针铁矿相比有所提高,增加至2.34 e V。此外还考查了不同阳离子掺杂及纯相针铁矿与Fe(Ⅱ)构成的复合系统对邻硝基苯酚(2-NP)的还原效果,研究表明,在溶液pH=6和25℃等的条件下,上述还原转化反应符合准一级动力学方程。其中,Fe(Ⅱ)/Al^(3+)掺杂针铁矿复合系统对2-NP的降解效果最好,在120 min时就达到了100%去除率,在一定浓度范围内,随着2-NP浓度的升高,2-NP的还原速率降低。而且,Fe(Ⅱ)/Al^(3+)-针铁矿复合系统速率常数(k)随着溶液的pH值增大而升高。In this paper, modified goethite samples doped with different cations were prepared and characterized. XRD showed that doping cations Mn^2＋, Cr^3＋ and Al^3＋ didn＇t significantly change the types of crystal structure for α-FeOOH, indicating that the cations were doped into the α-FeOOH lattice, and solid solutions were respectively formed when Fe3＋ was partially replaced by Mn^2＋, Cr^3＋ and Al^3＋. The infrared analysis also showed a similar result. The results of TGA-DTA and TEM exhibited that these metal cations had entered the goethite lattice. By UV-vis diffuse reflection spectrum analysis, it was found that the band gaps of goethite doped with Mn^2＋ and Cr^3＋ were 2.18 and 2.24 eV, respectively, lower than the band gap of pure goethite （2.28 eV）; in contrast, the band gap of goethite doped with Al^3＋ was increased to 2.34 eV. In addition, the reductive effects of different complex systems of Fe（Ⅱ） combined with pure goethite and its counterparts doped with above three different cations on 2-NP reduction were investigated, and it was found that the 2-nitrophenol （2-NP） reductive transformation followed the pseudo-first-order kinetics under the condition pH=6 and temperature 25℃. The system Fe（Ⅱ）/goethite doped with Al^3＋ showed the best degradation of 2-NP with a removal efficiency of 100% within 120 min. However, the reductive rate of 2-NP transformation was clearly reduced with the initial concentrations of 2-NP increasing to a certain extent. Moreover, the rate constant （k） of the system doped with Al^3＋ was increased with the increment of the solution pH value.

关 键 词：阳离子掺杂针铁矿 亚铁离子 邻硝基苯酚(2-NP) 还原转化 

分 类 号：P579[天文地球—矿物学]