Directing the amount of CNTs in CuO–CNT catalysts for enhanced adsorption-oriented visible-light-responsive photodegradation of p-chloroaniline

Copper oxide (CuO, 10–90 wt%) was loaded onto carbon nanotubes (CNTs) by electrosynthesis method. The catalysts (CuO/CNT) were characterized by XRD, nitrogen adsorption–desorption, ESR, FTIR, Raman, and XPS spectroscopy. The results indicated that a lower amount of CuO was dispersed well on the CNT, while higher loading was agglomerated, producing large-size crystallites, hence resulting in lower specific surface area. Adsorption studies revealed that the isotherms are fitted well with the Langmuir model. Moreover, the n value that was obtained from Freundlich model indicated that adsorption process is chemisorption. Photodegradation of p-chloroaniline (PCA) under visible light irradiation demonstrated that the 50 wt% CuO/CNT catalyst gave the highest degradation (97%). It was concluded that C–N moieties of PCA were chemisorbed on the catalyst prior to photodegradation, while the Cu–O–C bonds, surface defects and oxygen vacancies were the main active site in enhancing the subsequent photodegradation. The kinetics of photodegradation were correlated with pseudo-first-order model, verifying the surface reaction was the controlling step. Remarkable mineralization results of PCA were attained by TOC (89.1%) and BOD₅ (50.7%). It was also evidenced that the catalyst has a good potential toward degradation of various endocrine disruption compounds.