Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, 600036, Tamil Nadu, India.
Environmental Engineering Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, 600036, Tamil Nadu, India.
Chemosphere. 2024 Sep;364:143071. doi: 10.1016/j.chemosphere.2024.143071. Epub 2024 Aug 9.
Two microwave (MW) responsive heterojunction nanocomposite catalysts, i.e., α-BiO/CoFeO (BO/CFO) and ZnO/CoFeO (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 ∼90 °C, 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 (O) and hydroxyl radicals (OH) both played influential roles. The Z-scheme heterojunction of BO/CFO allowed the formation of O 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, Co/Co and Fe/Fe redox cycles have promoted O 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.
两种微波（MW）响应的异质结纳米复合材料催化剂，即α-BiO/CoFeO（BO/CFO）和 ZnO/CoFeO（ZO/CFO），通过顺序热分解和共沉淀法合成，重量比为 70/30、50/50、30/70，用于在 MW 照射下降解四环素（TC）。通过 XRD、FT-IR、SEM、VSM、UV-DRS、XPS、BET 等的特征结果确认了所需催化剂的形成。使用批 MW 实验，优化了催化剂剂量、pH 值、初始 TC 浓度、反应温度和 MW 功率以去除 TC。在以下反应条件下：催化剂剂量∼1 g/L，初始 TC 浓度∼1 mg/L，温度∼90°C，MW∼450 W，BO/CFO 和 ZO/CFO 在 5 分钟后分别显示出∼97.55%和 88.23%的 TC 降解。这两种催化剂对 TC 降解的催化响应差异表明了它们之间反射损耗（RL）的差异。由于清除效应，其他竞争性阴离子的存在会影响 TC 的去除效率。自由基捕获研究表明，在 ZO/CFO 的情况下，羟基自由基在 TC 降解中起重要作用，而对于 BO/CFO，超氧化物（O）和羟基自由基（OH）都发挥了重要作用。BO/CFO 的 Z 型异质结允许形成 O，但在 ZO/CFO 的 II 型异质结中，由于价带位置，相同的 O 被抑制。在催化剂表面产生了介电损耗、磁损耗、界面极化和高导电性、“热点”，以及在异质结处电子-空穴分离，这是产生活性氧物质的原因。此外，Co/Co 和 Fe/Fe 氧化还原循环促进了过硫酸盐应用过程中 O 和硫酸根自由基的产生。在这两种 MW 响应催化剂中，BO/CFO 可以成为在 MW 照射下无需添加其他氧化化学品即可快速破坏废水中新兴有机污染物的潜在材料。
