两种微波(MW)响应异质结纳米复合催化剂,即,α-Bi2O3/CoFe2O4(BO/CFO)和ZnO/CoFe2O4(ZO/CFO),通过顺序热分解和共沉淀方法合成了重量百分比为70/30、50/50、30/70的,并用于在MW辐射下降解四环素(TC)。通过XRD的表征结果证实了所需催化剂的形成,FT-IR,SEM,VSM,UV-DRS,XPS,BET,等。使用批量MW实验,催化剂剂量,pH值,初始TC浓度,反应温度,和MW功率进行了优化以去除TC。在以下反应条件下:催化剂剂量~1g/L,初始TC浓度~1mg/L,温度90ºC,MW~450W,BO/CFO,ZO/CFO的TC降解率为97.55%和88.23%,分别,5分钟后。对TC降解的催化响应的差异表明这两种催化剂之间的反射损失(RL)的差异。由于清除作用,其他竞争性阴离子的存在会影响TC的去除效率。自由基捕获研究揭示了在ZO/CFO的情况下,羟基自由基对TC降解的显着贡献,而对于BO/CFO来说,超氧化物(●O2-)和羟基自由基(●OH)均起影响作用。BO/CFO的Z方案异质结允许形成●O2-,但由于价带位置,在ZO/CFO的II型异质结中也受到抑制。介电损耗,磁损耗,界面极化,和高导电性,“热点”在催化剂表面上产生,同时在异质结处电子-空穴分离,负责活性氧的产生。此外,Co3+/Co2+和Fe3+/Fe2+氧化还原循环促进了过硫酸盐施用过程中O2-和硫酸根的产生。在两种MW响应催化剂中,BO/CFO可能是一种在MW辐射下无需使用其他氧化性化学物质即可快速破坏废水中新兴有机污染物的潜在材料。
Two microwave (MW) responsive heterojunction
nanocomposite catalysts, i.e., α-Bi2O3/CoFe2O4 (BO/CFO) and ZnO/CoFe2O4 (ZO/CFO), with weight% ratio of 70/30, 50/50, 30/70 were synthesized by sequential thermal decomposition and co-precipitation methods, and used for the degradation of tetracycline (TC) under MW irradiation. The formation of desired catalysts was confirmed through the characterization results of XRD, FT-IR, SEM, VSM, UV-DRS, XPS, BET, etc. Using batch MW experiments, the catalyst dose, pH, initial TC concentration, reaction temperature, and MW power were optimized for TC removal. Under the following reaction conditions: catalyst dose ∼1 g/L, initial TC concentration ∼1 mg/L, temperature ∼90ºC, MW ∼450 W, BO/CFO, and ZO/CFO showed ∼97.55% and 88.23% TC degradation, respectively, after 5 min. The difference in the catalytic response against TC degradation indicated the difference in reflective loss (RL) between these two catalysts. The presence of other competitive anions has affected the removal efficiency of TC due to the scavenging effect. The radical trapping study revealed the significant contribution of TC degradation by hydroxyl radicals in the case of ZO/CFO, whereas for BO/CFO, superoxide (●O2-) and hydroxyl radicals (●OH) both played influential roles. The Z-scheme heterojunction of BO/CFO allowed the formation of ●O2- but the same was inhibited in type-II heterojunction of ZO/CFO due to the valance band position. The dielectric loss, magnetic loss, interfacial polarization, and high electrical conductivity, \'hotspots\' were produced over the catalyst surface alongside electron-hole separation at heterojunctions, which were responsible for the generation of reactive oxygen species. In addition, Co3+/Co2+ and Fe3+/Fe2+ redox cycles have promoted ●O2- and sulfate radical production during persulfate application. Among the two MW responsive catalysts, BO/CFO could be a potential material for rapidly destroying emerging organic pollutants from wastewater without applying other oxidative chemicals under MW irradiation.