ABSTRACT

The current environmental problems urgently require researchers to seek an environmentally friendly, effective and easy to operate sewage treatment method. Graphite carbon nitride (g-C₃N₄), which has the advantages of simple preparation, safety, non-toxicity and chemical resistance, was expected to become a photocatalyst for solving environmental pollution. However, the performances of g-C₃N₄ still have some limitations that the electron hole recombination is fast and the powder is not easy to recover. In this study, zinc-doped graphite carbon nitride photocatalyst (Zn-g-C₃N₄) was mixed with polyacrylonitrile (PAN) to produce photocatalyst fibres by electrospinning. It not only solves the problem that the powder catalyst is difficult to recycle, but also effectively inhibits the recombination of photoelectron-hole pairs. Zn-g-C₃N₄/PAN has good photocatalytic activity for the simultaneous reduction of hexavalent chromium and degradation of pharmaceuticals. When organic pollutants are present, the reduction efficiency of hexavalent chromium was improved without affecting its own removal efficiency. The potential application value of Zn-g-C₃N₄/PAN catalytic fibre was further explored by simulating the complex actual water environment. The composite fibre can be easily reused and keep its superior photocatalytic performance. The mechanism of pharmaceuticals degradation was proposed, in which $\bullet {\mathrm{O}}_2^{-}$ is the most important active species, which leads to the oxidation of pharmaceuticals. Besides, the photoelectrons generated by the catalyst can reduce the toxic hexavalent chromium. The efficiency of Zn-g-C₃N₄ to remove pollutants is improved by PAN fibre as a carrier, which not only solves the problem of difficult recovery of powder catalysts, but also provides more active sites.

摘要

当前的环境问题迫切需要研究人员寻求一种环境友好、有效且易于操作的污水处理方法。石墨碳氮化物（gC ₃ N ₄）具有制备简单、安全、无毒、耐化学等优点，有望成为解决环境污染的光催化剂。但gC ₃ N ₄的性能仍存在电子空穴复合快、粉体不易回收等局限性。本研究采用锌掺杂石墨氮化碳光催化剂（Zn-gC ₃ N ₄) 与聚丙烯腈 (PAN) 混合，通过静电纺丝生产光催化剂纤维。不仅解决了粉末催化剂难以回收利用的问题，而且有效抑制了光电子-空穴对的复合。Zn-gC ₃ N ₄ /PAN对同时还原六价铬和降解药物具有良好的光催化活性。当有机污染物存在时，六价铬的还原效率得到提高，而不会影响其自身的去除效率。_{Zn-gC 3} N ₄的潜在应用价值/PAN催化纤维通过模拟复杂的实际水环境进一步探索。复合纤维易于重复使用并保持其优越的光催化性能。提出了药物降解的机理，其中$\bullet {\mathrm{○}}_2^{-}$是最重要的活性物质，会导致药物的氧化。此外，催化剂产生的光电子可以还原有毒的六价铬。以PAN纤维为载体，提高了Zn-gC ₃ N ₄对污染物的去除效率，不仅解决了粉末催化剂难以回收的问题，而且提供了更多的活性位点。