Photocatalytic Degradation of Ammonium-rich Wastewater by CuO-based Nanocomposites

Copper oxide (CuO) is a promising photocatalyst for decomposing inorganic nitrogen compounds, especially ammonium ions, in wastewater under UV light irradiation. This work aims to develop CuO-based nanocomposites using the reduced 2D graphene oxide (rGO) and 1D multi-walled carbon nanotubes (MWCNTs) with mixed design ratios for photocatalytically degrading ammonium ions under UV illumination. The CuO-based nanocomposites were prepared by combining precipitation and annealing methods. The CuO nanoparticles (NPs) were well decorated on rGO and MWCNTs. The UV-Vis spectra revealed that the CuO-rGO and CuO/(rGO-MWCNTs) can effectively utilize photons from the visible spectrum. Thus, CuO-rGO and CuO/(rGO-MWCNTs) established acceptable photocatalytic action and effective ammonium ions removal from wastewater under UV irradiation compared to CuO. The determined band gap energy by UV–Vis spectra of the synthesized CuO was about 1.33 eV, which was reduced to 1.27 eV, 1.17 eV, and 1.14 eV with the CuO-rGO, CuO/(rGO-MWCNTs “70:30”), and CuO/(rGO-MWCNTs “50:50”) nanocomposites, respectively. According to the findings, CuO-base nanostructures have a solid quantum size confinement effect because their band gap energy is higher than that of CuO-based nanocomposites. The developed CuO-rGO nanocomposites showed effective photocatalytic activity of 91.4, and the designed ratio of CuO/(rGO-MWCNTs “70:30”) showed a comparable value of 90.6 ammonia degradation compared to CuO NPs (87.2%) after two hours under UV light irradiation. Thus, utilizing CuO-based rGO and MWCNTs photocatalysts for ammonium-nitrogen (NH₄⁺-N) degradation by UV light is one of the most promising approaches in wastewater treatment.

Carbon-based nanocomposites of CuO NPs were synthesized by co-precipitation method.