Abstract

In this work, iron-doped graphite carbon nitride (Fe-g-C₃N₄) was integrated with CoMoO₄ through a simple hydrothermal route and high temperature calcination to synthesize distinctive composites, aiming to create a promising heterogeneous catalyst to active peroxymonosulfate (PMS) for the degradation of methylene blue (MB), a widely used organic dye. The characterization results, including SEM, EDX, FTIR, XRD and XPS, indicated that the crystal structure and physicochemical properties of CoMoO₄-Fe-g-C₃N₄ have changed after modification, with rougher surface and efficient catalytic activity. The effects of several operational factors (catalyst dosage, oxidant dosage, reaction temperature and initial pH) were also extensively evaluated. Under the condition of CoMoO₄-Fe-g-C₃N₄=0.1 g L⁻¹, oxidant = 2.0 mM, dye = 100 mg/L, T = 25 °C, the MB in the CoMoO4-Fe-g-C3N4/PMS catalytic system can reach almost complete degradation in 90 minutes without pH adjustment. Further, stability experiment showed that the CoMoO₄-Fe-g-C₃N₄ catalysts exhibited high stability and superior reusability, with 80% removal rate even after five concessive cycles of use. Additionally, through radical quenching experiments, it proved that SO₄^•− radicals were dominant and HO^• radicals also worked in the MB degradation process. An underlying mechanism was proposed based on the detection of XPS results that both radical and non-radical degradation pathways existed during MB degradation process. The electron transfer from high-valence iron species (Fe^IV=O) to MB resulting in the degradation of MB through a non-radical mechanism. From the investigation, the CoMoO₄-Fe-g-C₃N₄ composite was proved to have potential superiority as a promising catalyst for the degradation of refractory organic contaminant removal from water.

摘要

在这项工作中，铁掺杂的石墨碳氮化物 (Fe-gC ₃ N ₄ )通过简单的水热路线和高温煅烧与 CoMoO ₄结合以合成独特的复合材料，旨在创造一种有前途的多相催化剂来活化过硫酸盐 (PMS)用于降解亚甲蓝 (MB)，一种广泛使用的有机染料。SEM、EDX、FTIR、XRD和XPS等表征结果表明CoMoO ₄ -Fe-gC ₃ N ₄的晶体结构和理化性质改性后发生了变化，具有更粗糙的表面和高效的催化活性。还广泛评估了几个操作因素（催化剂用量、氧化剂用量、反应温度和初始 pH 值）的影响。在 CoMoO ₄ -Fe-gC ₃ N ₄ =0.1 g L ^-1，氧化剂 = 2.0 mM，染料 = 100 mg/L，T = 25 °C 条件下，CoMoO4-Fe-g-C3N4/ PMS催化体系无需调节pH即可在90分钟内达到几乎完全降解。此外，稳定性实验表明，CoMoO ₄ -Fe-gC ₃ N ₄催化剂表现出高稳定性和优异的重复使用性，即使在连续使用五次循环后，去除率仍可达 80%。此外，通过自由基猝灭实验，证明SO ₄ ^•-自由基占主导地位，而HO ^•自由基也在MB 降解过程中起作用。基于XPS结果的检测提出了一种潜在机制，即MB降解过程中同时存在自由基和非自由基降解途径。从高价铁物质（Fe ^IV = O）到 MB的电子转移导致 MB 通过非自由基机制降解。经查，CoMoO ₄ -Fe-gC ₃ N ₄ 复合材料被证明作为一种有前途的催化剂具有潜在的优势，可用于降解水中的难降解有机污染物。