The Study Of New Photocatalytic Bi(?) Coordination Polymers With Pyridine Carboxylic Acid

In the nature Bismuth?Bi?has the advantages of relatively cheap,low toxicity an d low radioactivity of heavy metal elements.Bismuth compounds has been used in th e glowing,magnetic materials,catalysis,and many other fields as well as a wide rang e of applications.At present,in the development of the modern "green chemistry" tre nd under the requirement of "sustainable development " and economic society,develop new bismuth compound system function has important scientific significance.In terms of photocatalytic degradation of organic pollutants,bismuth compound system function has good photocatalytic activity than traditional photocatalyst such as TiO2,the narro w forbidden band width may have to be visible stimulate,achieve the purpose of the degradation of organic pollutants in the visible light.In this paper,we used 2,5-pyridi ne carboxylic acid and 2,6-pyridine carboxylic acid as an organic ligand was synthesiz ed with bismuth nitrate preparation for 9 cases of Bi???coordination polymers: Bi2?2,6-Hpydc?2?2,6-pydc?2·2H2O?1?,K[Bi2?H2O?2?2,6-Hpydc??2,6-pydc?3]·3H2O?2?,[Hbim]2[B i?2,6-Hpydc?4?2,6-pydc?2]·4H2O?3?,[H2bpy]2/2[Bi?2,6-Hpydc??2,6-pydc?2]·6H2O?4?,[H2bpp][Bi?2,6-Hpydc??2,6-pydc?2]·7H2O?5?,[H2bpe]1.5[Bi?2,6-pydc?3]·4H2O?6?,Bi5?O H?5?2,6-pydc?5?H2O?·4H2O?7?,Bi?2,5-Hpydc??2,5-pydc??H2O??8?and [Hbpe][Bi?2,5-Hpy dc?2?2,5-pydc?]·H2O?9??2,6-H2 pydc = 2,6-pyridine dicarboxylic acid,2,5-H2 pydc = 2,5-pyridine dicarboxylic acid;bim = benzene and imidazole;bpy = 4,4'-pyridine;bpp =1,3-2?4-pyridyl?propane,bpe = trans 1,2-?4-pyridyl?ethylene?.Complexes 1-7 are used with bismuth nitrate and 2,6-pyridine dicarboxylic acid as the foundation,by adding different neutral ligand to fit into a series of coordination polymer.Complexe 7 form 2d layer structure through ten nuclear Bi-O polyhedron unit;Complexes 8-9 are used with bismuth nitrate and 2,5-pyridine dicarboxylic acid as the basis,by adding different neutral ligand to fit into two cases of coordination polymer.Complexes 1-4,6,7 and 8-9 photodegradation performance are studied,making to simulate pollutants for rhodamine B and methylene blue test.Taking the degradation of rhodamine B as an example,under the UV irradiation of 165 W mercury lamp,complexes 1-4,6,7 are nearly completely degradation of the 20 mg/L rhodamine B solution in a certain time,just showing different rates.Complex 2 is within 45 min,while complex 1 is within 120 min.Complex 8 can be degraded rhodamine B to 55.4%.Under the condition of visible light,complex 9 can be degraded rhodamine B completely within 100 min,showing good photocatalytic performance under LED lamp.Taking complexes 1,3,4,6,7,8 and 9 as precursors in the muffle furnace for calcination,prepare micro/nano Bi₂O₃ materials with different morphology: Bi₂O₃-1,Bi₂O₃-3,Bi₂O₃-4,Bi₂O₃-6,Bi₂O₃-7,Bi₂O₃-8 and Bi₂O₃-9.Bi₂O₃-1 is layered shape,the size of particles are about 300-500 nm;Bi₂O₃-3 are arranged stick tightly,the size of particles are about 200-200 nm;Bi₂O₃-4 is rod-shaped,after enlarge the surface is made up of smaller circular particles,the size of particle is about 100-300 nm;Bi₂O₃-6 is accumulated together,making up of the flake after enlargement,the size of particles are about 1-2 mm;After enlargement the surface of spherical Bi₂O₃-7,is composed of sheet material,2-5 mm;The morphology of Bi₂O₃-8 is similar to Bi₂O₃-3,the difference is the surface is not smooth,the size of small particles are 2-5 mm;Bi₂O₃-9 are fibrous,the size of particles are about 1-2 mm.Taking the micro/nano Bi₂O₃ for photocatalytic degradation of rhodamine B and methylene blue,we found that micro/nano Bi₂O₃ has good catalytic activity for rhodamine B,while the big differences of methylene blue.It shows that different morphology of micro/nano Bi₂O₃ material has different performance of photodegradation,and the same micro/nano Bi₂O₃ materials for different pollutants also show certain selectivity.