氨基化金属有机骨架对废水中新型烟碱类农药的去除机制

Removal mechanism of neonicotinoid insecticides in wastewater by aminated metal-organic framework

为有效去除水中多种新型烟碱类农药(neonicotinoid insecticides,NNIs),通过水热法合成了氨基化金属有机骨架纳米材料(NH2-MIL-101),结合材料的理化性质表征结果及其对NNIs的吸附性能,探究NH2-MIL-101对水中NNIs的去除机制。结果表明:NH2-MIL-101对6-氯烟酸、啶虫脒、噻虫胺、吡虫啉、噻虫嗪的去除率优于MIL-101,最高可达86%、92%、30%、63%、47%,且20 min内可达到吸附平衡;π-π作用和分子空间位阻的不同导致NH2-MIL-101对不同NNIs的去除存在差异;对于不同NNIs的去除,溶液最佳pH存在差异,综合而言,在pH为3~7时去除效果较好;水中共存阴离子Cl-(0~1000 mg·L^-1)与SO24-(0~100 mg·L^-1)对5种NNIs的去除效果影响不大,HCO3-(0~100 mg·L^-1)对NNIs的去除呈现明显的抑制作用。综合上述结果,NH2-MIL-101对NNIs的吸附符合Langmuir模型和准二级动力学模型,具有良好的吸附效果,且能够重复利用5次,在NNIs的水处理中具有应用价值。

To effectively remove neonicotinoid insecticides(NNIs)in water,aminated metal organic frameworks(NH2-MIL-101)was synthesized by hydrothermal method in this study.Based on the physicochemical properties of the synthesized materials and their sorption performance for NNIs,the removal mechanism of NNIs in water by NH2-MIL-101 was explored.The results showed that the removal rates of 6-chlorniacin,acetaminidine,thiamethylamine,imidacloprid and thiamethoxam NNIs by NH2-MIL-101 were higher than those by MIL-101.The highest removal rates were 86%,92%,30%,63%and 47%for 6-chlorniacin,acetaminidine,thiamethylamine,imidacloprid and thiamethoxam,respectively,and the adsorption equilibrium could be achieved within 20 min.The differences ofπ-πinteraction and molecular steric hindrance resulted in the different removal rates of various NNIs by NH2-MIL-101.In general,good removal effect occurred at pHs 3~7,though the optimal pH was different for specific NNI.The coexisting anions of Cl-(0~1000 mg·L^-1)and SO24-HCO3-significant inhibitory effect on the removal of these NNIs.In conclusion,Langmuir model and the quasi-secondorder kinetic model had a good fitting for the sorption process of NNIs by NH2-MIL-101 with good adsorption effects,and the material could be reused for 5 times.Therefore,NH2-MIL-101 can be a promising material for application in NNIs-containing water treatment.