Green synthesis of copper oxide and manganese oxide nanoparticles from watermelon seed shell extract for enhanced photocatalytic reduction of methylene blue

Abstract

NOVELTY STATEMENT The copper oxide (CuO) and manganese oxide (MnO) nanoparticles (NPs) were synthesized from watermelon seed extract by the green synthesis method. The watermelon seed shell, which is left as waste to the environment, has been transformed into a product with high added value. The particle sizes of CuO and MnO NPs were determined to be in the range of 15-97 and 6-51 nm, respectively. The photocatalytic performance of the CuO and MnO NPs used as catalysts were investigated for the photocatalytic reduction of methylene blue in an aqueous solution. In the photocatalytic reduction of methylene blue, sodium borohydride (NaBH4) was used as the reducing agent. The CuO and MnO NPs were capable to remove 96.58% (in 70 min) and 96.60% (in 140 min) of methylene blue, respectively. It was determined that UV light was effective in the photocatalytic reduction of methylene blue with NaBH4. The reaction rate coefficient for the photocatalytic reduction of methylene blue with CuO and MnO NPs was calculated as 0.0426 and 0.0235 min(-1), respectively.