功能化氮掺杂空心碳球的制备及其对Pb^(2+)的吸附特性

Preparation of Functionalized N-doped Hollow Carbon Spheres and Their Adsorption Properties for Pb^(2+)

水热法合成氮掺杂空心碳球(CS),通过活化反应分别将尿素和硫脲接枝到表面富含羟基的空心碳球上,制备了两种用于去除Pb^(2+)的新型增强吸附剂Urea-CS和Thiourea-CS。在吸附剂质量为40 mg、Pb^(2+)初始质量浓度为800 mg/L、溶液pH为6和温度为25℃的吸附实验条件下,Thiourea-CS和Urea-CS的最大吸附量分别为212.35 mg/g和166.54 mg/g,去除率分别为42.30%和33.30%,均符合Langmuir吸附模型。热力学研究表明,吸附是一个自发的、吸热的、熵增加的过程。准二级吸附动力学模型与Urea-CS和Thiourea-CS的实验数据吻合。200 mg/L的Pb^(2+)溶液经过5次吸附-解吸循环后,Urea-CS和Thiourea-CS仍具有良好的稳定性和重复性,去除率分别为95.24%和98.40%。XPS结果表明,氮/氧与Pb^(2+)之间的络合作用在吸附机制中起重要作用。该方法对Pb^(2+)的去除具有良好的可重复性和选择性。

Two new enhanced adsorbents Urea-CS and Thiourea-Cs for Pb^(2+)removal were prepared by hydrothermal synthesis of N-doped hollow carbon spheres(CS).Urea and Thiourea were grafted onto hollow carbon spheres with hydroxy-rich surface through activation reaction,respectively.Under the adsorption experimental conditions of adsorbent mass 40 mg,initial Pb^(2+)concentration 800 mg/L,solution pH 6 and temperature 25℃,the maximum adsorption amounts of Thiourea-CS and Urea-CS were 212.35 mg/g and 166.54 mg/g.The removal rates were 42.30% and 33.30%,respectively,which were consistent with Langmuir adsorption model.Thermodynamic studies show that adsorption is a spontaneous,endothermic and entropy increasing process.The quasi-secondary adsorption kinetics model is consistent with the experimental data of Urea-CS and Thiourea-CS.After five sorbation-desorption cycles of 200 mg/L Pb^(2+)solution,Urea-CS and Thiourea-CS still had good stability and repeatability,with removal rates of 95.24%and 98.40%,respectively.The XPS results show that the complexation between nitrogen/oxygen and Pb^(2+)plays an important role in the adsorption mechanism.The method has good repeatability and selectivity for the removal of Pb^(2+).