Comparative investigation of oxidative degradation of organic dye in the presence of H2O2 and CuO nanoparticles synthesized by sol–gel method and green synthesis using flower (Matricaria chamomilla) extract

2 Vytautas Magnus University, 58 K. Donelaičio Street, 44248 Kaunas, Lithuania In this study, CuO nanoparticles have been synthesized via a simple sol– gel method and green synthesis using flower (Matricaria chamomilla) extract. XRD analysis of the synthesized CuO nanoparticles clearly indicated a crystalline nature with a monoclinic structure regardless of the method of synthesis, while SEM revealed that the used synthesis methods affected the morphology of the CuO nanoparticles. The oxidative degradation kinetics of the organic dye Methyl Orange (MO) in the presence of the synthesized catalyst CuO and H2O2 has been investigated and compared depending on the dye concentration, reaction time and temperature. The catalytic activity of CuO was studied by measuring the UV–visible spectrum of the MO dye solution treated with CuO and H2O2. It was determined that the MO degradation reaction kinetics followed the pseudo-first-order mechanism. Thermodynamic studies indicated an endothermic nature (∆H# = +73.03 kJ mol–1) and a decrease in randomness at the catalyst CuO/solution interface during the reaction (∆S# = –0.021 kJ mol–1 K–1). At the same conditions, the green synthesized CuO nanoparticles exhibit similar activity properties as CuO synthesized using the sol–gel method. Besides, the green synthesis of CuO nanoparticles is simple and uses a small number of chemicals. The obtained CuO may be a promising catalyst for the oxidative degradation of organics, especially used in medical procedures.