氮/硫双掺杂介孔碳磁性复合物固相萃取食用植物油中重金属的吸附分离机理研究

Because of the complex matrix of vegetable oils, the sample pretreatment has become a bottleneck of restricting the fast detection and control of metallic contaminants in vegetable oils. Rapid separation and enrichment of heavy metals from aqueous solution through solid phase extraction (SPE) adsorbents have been widely reported. However, as little was known about the adsorption behavior of heavy metals in vegetable oils, the application of SPE in vegetable oils is restricted in theoretical and practical aspects. In order to reveal this issue, a particular solid adsorbent was designed to study the mechanism of adsorption and separation of heavy metals in vegetable oils in this project. Firstly, a novel magnetic N/S co-doped mesoporous carbon composite (Fe3O4@N-S-mC) with high adsorption capacity will be prepared by hard template method. Secondly, static adsorption experiments will be carried out to investigate the effects of types of matrix on the adsorption and desorption of heavy metals onto Fe3O4@N-S-mC. The adsorption thermodynamic and kinetics parameters of heavy metals in adsorption process will be calculated, and the adsorption characteristics of heavy metals by Fe3O4@N-S-mC in vegetable oils will be evaluated. Finally, the adsorption and separation mechanism of Fe3O4@N-S-mC for the heavy metals in vegetable oils will be studied based on the above results and spectrum analysis of characteristic signals of atoms and functional groups. The research results of this project will take an in-depth look at the interaction mechanism between the solid adsorbent and heavy metals in vegetable oils, and provide basic theory and technical support to develop new methods for the fast detection and elimination of heavy metals in vegetable oils.

植物油的复杂基质特性，使得前处理成为了制约植物油中重金属现场快速检测与控制的瓶颈。诸多固相萃取材料已被报道可以实现水体中重金属快速分离富集，但是对于植物油中重金属，相关吸附分离机制尚不明确，应用缺乏理论依据。针对这一问题，本项目拟通过设计固相材料开展植物油中重金属的吸附分离机理研究。首先，通过硬模板法制备对重金属具有高吸附性能的氮/硫双掺杂介孔碳磁性复合物Fe3O4@N-S-mC；然后，通过静态吸附试验，研究不同类型基质中重金属在材料上吸附与解吸行为的规律，获得吸附过程中吸附热力学和动力学参数，明确植物油中重金属的吸附特性；最后，利用谱学分析技术跟踪表征吸附过程Fe3O4@N-S-mC原子及官能团的谱学特征变化，揭示其吸附分离植物油中重金属机理。通过本项目的研究，将深入了解固相材料与重金属在植物油中的相互作用机制。为拓展植物油中重金属快速检测方法以及重金属消除方法提供理论基础和技术支撑。

食用植物油中的重金属不仅作为催化剂加速植物油油脂氧化酸败，影响植物油品质，而且能够经饮食进入人体，危害人体健康。植物油的复杂基质特性，使得样品前处理成为了制约植物油中重金属检测的瓶颈。本项目以氮/硫功能化磁性复合物吸附萃取重金属为切入点，对食用油中重金属的萃取分离行为进行了研究，开发了食用油中重金属的检测方法，可为拓展植物油中重金属快速检测方法以及重金属消除方法提供理论基础和技术支撑。具体结果如下：（1）基于三氯化铁、氮硫源（甘氨酸、三聚氰胺、硫脲等），通过高温碳化，可得到一系列具有大比表面积、良好磁性的氮、硫等活性原子（基团）掺杂磁性复合物。氮掺杂磁性复合物对重金属Pb具有较好的萃取分离性能，对Pb的吸附行为符合准二级动力学吸附模型以及Langmuir模型。通过XPS、FTIR深入解析表明吸附机理是Pb的空轨道与磁性复合物表面氮原子之间存在静电吸附和共价作用。采用1 M盐酸可以实现Pb的定量洗脱，建立了磁固相萃取-ICP-MS联用的方法实现了食用油中Pb的灵敏准确检测。（2）基于点击化学反应，构建了富硫笼型聚倍半硅氧烷功能化的磁性复合物（Fe3O4@SiO2/POSS-SH），在超声辅助下，在pH=5-8范围内，Fe3O4@SiO2/POSS-SH对Cd和Pb可以实现高效分离和富集，可达到100倍富集倍数。（3）采用稀酸可以实现食用油中重金属的萃取分离，建立了超声辅助稀酸提取结合ICP-MS测定稻米油中重金属Cd的方法，检出限为0.08 ng g-1。采用Triton X-114作表面活性剂可以有效萃取食用油中重金属Cd，建立了破乳诱导萃取法结合ICP-MS测定各类食用油中重金属Cd含量的方法，检出限为0.031 ng g-1。（4）为进一步吸附消除重金属残留，开发了绿色可食性的壳聚糖-果胶凝胶珠，对Cu(II), Cd(II), Hg(II)和Pb(II)的吸附过程符合准二级动力学模型和Langmuir模型，对Cu(II)、Cd(II)、Hg(II)和Pb(II)的理论最大吸附容量分别为169.4、177.6、208.5和266.5 mg/g，将为液体食品中重金属的吸附减控提供了很好的借鉴作用。本项目相关研究成果完成了项目规定的各项任务和指标，达到了预期研究目标。