磺酸基改性二维Ti_(3)C_(2)T_(x)纳米材料制备与Pb^(2+)吸附性能

Study on preparation of two-dimensional Ti_(3)C_(2)T_(x) nanomaterials modified by sulfonic acid groups and the adsorption performance of lead(Ⅱ)ion

对二维Ti_(3)C_(2)T_(x)材料进行了磺酸基团接枝改性(Ti_(3)C_(2)T_(x)−SO_(3)H),表征了改性前后微观结构的变化,研究了对重金属Pb^(2+)的吸附行为与机制。XRD、FTIR及EDS表明磺酸基团在Ti_(3)C_(2)T_(x)表面成功接枝,而SEM则发现Ti_(3)C_(2)T_(x)−SO_(3)H呈现较Ti_(3)C_(2)T_(x)更轻薄的层状结构。改性后,Ti_(3)C_(2)T_(x)−SO_(3)H对重金属Pb^(2+)20 min内达到吸附平衡,最大吸附量达到733.6 mg·g^(−1),较Ti_(3)C_(2)T_(x)吸附量提升了23%,且吸附量随着pH(2~6)的增加而逐渐增大,在Mg^(2+)、Ca^(2+)、Co^(2+)、Zn^(2+)等共存离子的干扰下,仍保持较高的吸附水平。机制分析表明,改性前后吸附过程均符合准二级动力学模型和Langmuir吸附等温线拟合模型,以单分子层化学吸附为主,但由于磺酸基团提供了更多的吸附饱和活性位点,并提高了Ti_(3)C_(2)T_(x)在水溶液中的分散性,使改性后对Pb^(2+)吸附性能更优异。

The two-dimensional Ti_(3)C_(2)T_(x) was modified by sulfonic acid group grafting(abbreviated as Ti_(3)C_(2)T_(x)−SO_(3)H),and its microstructure before and after the modification was characterized.The adsorption behavior and mechanism of heavy metal Pb^(2+)by the Ti_(3)C_(2)T_(x)−SO_(3)H were also investigated.XRD,FTIR and EDS analyses indicate that sulfonic acid group is successfully grafted on the surface of the Ti_(3)C_(2)T_(x),while SEM shows that the Ti_(3)C_(2)T_(x)−SO_(3)H has a lighter and thinner layered structure than the Ti_(3)C_(2)T_(x).Pb^(2+)adsorption by the Ti_(3)C_(2)T_(x)−SO_(3)H reaches equilibrium within 20 minutes.The maximum adsorption capacity of the Ti_(3)C_(2)T_(x)−SO_(3)H is 733.6 mg·g^(−1),which is 23% higher than the Ti_(3)C_(2)T_(x).And Pb^(2+)adsorption capacity by the Ti_(3)C_(2)T_(x)−SO_(3)H gradually increases with the increase of pH(2-6).Under the interference of coexisting ions such as Mg^(2+),Ca^(2+),Co^(2+)and Zn^(2+),the Ti_(3)C_(2)T_(x)-SO_(3)H still maintains a high level of Pb^(2+)adsorption.Pb^(2+)adsorption processes by both the Ti_(3)C_(2)T_(x) and the Ti_(3)C_(2)T_(x)−SO_(3)H fit well the pseudo second kinetic model and Langmuir isotherm model,suggesting that the adsorption processes are monolayer chemisorption.The Ti_(3)C_(2)T_(x)−SO_(3)H shows more excellent adsorption performance towards Pb^(2+)after adsorption mainly due to the more active sites provided by sulfonic acid group and the enhanced dispersion in aqueous solution.