A comparative study of TiO₂ nanoparticles and Cu(II)/TiO₂ nanocomposites on photodegradation of cinnamic acid (CA) under natural sunlight and artificial UV light

Abstract

Surfaces of TiO₂ nanoparticles decorated with Cu(II) nanoparticles as Cu(II)/TiO₂ nanocomposites, were prepared via a grafting process for a comparative study on photodegradation of recalcitrant cinnamic acid (CA) in aqueous solutions. In this study, CA was used as a model representing for the wastewater from agricultural industries containing phenolic compounds. Photodegradation of CA in the solutions by TiO₂ nanoparticles and Cu(II)/TiO₂ nanocomposites under natural sunlight and artificial UV light, were investigated. CA concentrations in the solutions were determined from the highest peak intensities at 271 nm, detected by a UV–Vis spectrophotometer. Under 90 min of the irradiation of both light sources, CA concentrations in the solutions were degraded by Cu(II)/TiO₂ nanocomposites higher and quicker than those of TiO₂ nanoparticles. According to the reusability test results, both TiO₂ nanoparticles and Cu(II)/TiO₂ nanocomposites have potential to reuse at least three cycles. Intermediate compounds formed during the irradiation of UV light, were identified by XPS analysis confirming that CA gradually changed to be nontoxic compounds. A mechanism for the CA photodegradation pathways in the solutions by Cu(II)/TiO₂ nanocomposites was proposed according to the analysis.

Graphical Abstract

Keywords:

• TiO₂ nanoparticles
• Cu(II)/TiO₂ nanocomposites
• Cinnamic acid (CA)
• natural sunlight
• artificial UV light

Disclosure statement

The authors declare that they have no competing interests.

Additional information

Funding

This work was financially supported by National Metal and Materials Technology Center (Grant No. P-17-51258 (SM-Project). Authors greatly appreciated National Metal and Materials Technology Center and European Comission-FP7 for allowing us the opportunity to use some facilities for the synthesis processes and characterizations supported under the projects (Grant Nos. P-13-00697 and 309846-PCATDES).