铁酸铋/钴镍层状双氢氧化物复合材料的制备及光催化活化过硫酸盐降解罗丹明B的性能

Preparation of bismuth ferrate/cobalt-nickel layered double hydroxide composites and photocatalytic activation of persulfate for Rhodamine B degradation

为获得可见光响应的高效过硫酸盐(Persulfate,PS)活化剂,以莫来石型铁酸铋(Bi_(2)Fe_(4)O_(9))微米棒为衬底,通过水热法在其表面负载氢氧化镍(Ni(OH)_(2)),随后将2-甲基咪唑钴(ZIF-67)沉积在Bi_(2)Fe_(4)O_(9)/Ni(OH)2表面,并与Ni(OH)2发生原位刻蚀反应形成网状钴镍层状双氢氧化物(CoNi-LDH),制得Bi_(2)Fe_(4)O_(9)/CoNi-LDH复合材料;通过SEM、XRD、XPS和UV-Vis等方法对材料进行表征,考察了Bi_(2)Fe_(4)O_(9)/CoNi-LDH材料在可见光下活化PS降解罗丹明B(Rh B)的性能,并通过自由基淬灭实验确定了主要活性物质。结果表明:2-甲基咪唑的添加量对复合材料的形貌和活化性能有显著影响,以0.50 mmol 2-甲基咪唑所制备的Bi_(2)Fe_(4)O_(9)/CoNi-LDH复合材料(BCN-2)具有1.92 eV的窄带隙,在可见光(λ>420 nm)和2 mmol/L的PS作用下,60 min内可将20 mg/L的Rh B降解98.1%,并且在pH值为3~9的环境中均能保持96.5%以上的降解率。自由基淬灭实验证明主要活性物质为SO_(4)·^(-)和1O_(2)。该研究为制备过渡金属基复合材料过硫酸盐催化剂提供了新途径。

To obtain an efficient persulfate(PS)activator responsive to visible light,nickel hydroxide(Ni(OH)_(2))was loaded on the surface of mullite-type bismuth ferrate(Bi_(2)Fe_(4)O_(9))microrods via a hydrothermal method.Subsequently,2-methylimidazole cobalt(ZIF-67)was deposited on the surface of Bi_(2)Fe_(4)O_(9)/Ni(OH)_(2)and underwent an in situ etching reaction with Ni(OH)_(2)to form a net-like cobalt-nickel layered double hydroxide(CoNi-LDH),resulting in the Bi_(2)Fe_(4)O_(9)/CoNi-LDH composite material.The material was systematically characterized by SEM,XRD,XPS and UV-Vis,and its performance in activating PS under visible light to degrade Rhodamine B(Rh B)was investigated.The main active substances were identified by free radical quenching experiments.The results showed that the addition amount of 2-methylimidazole significantly affected the morphology and activation performance of the composite material.The Bi_(2)Fe_(4)O_(9)/CoNi-LDH composite material(BCN-2)prepared with 0.50 mmol of 2-methylimidazole exhibited a narrow bandgap of 1.92 eV.Under the action of visible light(λ>420 nm)and 2 mmol/L PS,it could degrade 98.1%of 20 mg/L Rh B within 60 minutes,and maintain a degradation rate of above 96.5%in the pH range from 3 to 9.Radical quenching experiments demonstrated that the main active species were SO_(4·)^(-)and~1O_(2).This study provides a new way to prepare transition metal matrix composite persulfate catalysts.