| Boron（B）is an indispensable element for animals and plants.Although the content of boron is very small,it can promote the growth of bone and brain development.However,high concentrations of boron are harmful to human health and even death.Boron and its compounds have extensive applications in agriculture,industry,and other fields,resulting in a series of boron pollution problems.Therefore,development of simple and effective new adsorption materials is of great significance to reduce and remove boron from water.In this study,Co-Mn-ZIF-67,ZIF-8@Co-Mn-ZIF-67,and sodium carbonate modified Mn-ZIF-67 zeolite imidazole skeleton material were prepared,respectively.These materials were used to remove boron from aqueous solutions.The material properties including structure and characteristic were investigated in detail.Furthemore,many different environmental factors such as time,p H,and coexisting ions were also studied to explore the adsorption of boron.Based on the characterization analysis and combined with the batch experiments,the adsorption mechanisms were proposed.The main research findings and innovative points are listed as follows:1.Co-Mn-ZIF-67 zeolitic imidazole skeletal materials were prepared and the crystal structure of Co-Mn-ZIF-67 was similar to ZIF-67 zeolitic imidazole skeletal materials.Based on the characterization,Co-Mn-ZIF-67 showed a uniform regular dodecahedron shape.The adsorption of boron on Co-Mn-ZIF-67 could be simulated by the Freundlich model,indicating a multilayer adsorption.According to the kinetics study,the adsorption of boron was fitted by the first order kinetics model.The results confirmed that the adsorption capacity of Co-Mn-ZIF-67 for boron reached 29.7 mg﹒g-1under the conditions of 25℃and p H=6.2.According to the characterization,ZIF-8@Co-Mn-ZIF-67 had good morphology.The EDS and XPS spectra proved that boron was successful adsorbed on the surface of ZIF-8@Co-Mn-ZIF-67.Adsorption kinetics showed that the adsorption of boron was fitted by the first order kinetics model.The adsorption process was simulated by the Freundlich model,belonging to the multilayer adsorption.The removal capacity of ZIF-8@Co-Mn-ZIF-67 for boron achieved 31.1 mg﹒g-1under the condition of 25℃.The coexisting ion experiments proved that the material had a certain selectivity.The material still showed excellent adsorption performance after 10 cycles,indicating a good application prospect.3.The sodium carbonate modified Co-Mn-ZIF-67 zeolitic imidazole skeletal materials were prepared.The XRD characterization showed the complete crystal structure.According to the TGA/DSC characterization,the material had good thermal stability.The adsorption of boron was simultated by the pseudo-second-order kinetic model.The adsorption process was in line with the Langmuir adsorption model.The removal capacity of the material for boron achieved 57.4 mg﹒g-1under the condition of 25℃. |
