Green Synthesis and Characterization of CuO Nanoparticles Derived from Papaya Peel Extract for the Photocatalytic Degradation of Palm Oil Mill Effluent (POME)

You-Kang Phang,Mohammod Aminuzzaman,Lai-Hock Tey,Akira Watanabe,Md Akhtaruzzaman,Sayaka Ogawa,Ghulam Muhammad

doi:10.3390/su13020796

You-Kang Phang, Mohammod Aminuzzaman + Show 5 more

Open Access

https://doi.org/10.3390/su13020796

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Abstract

In recent years, the green chemistry based-approach for the synthesis of nanoparticles has shown tremendous promise as an alternative to the costly and environmentally unfriendly chemically synthesized nanoparticles. In this study, copper oxide nanoparticles (CuO NPs) were synthesized through a green approach using the water extract of papaya (Carica papaya L.) peel biowaste as reducing as well as stabilizing agents, and copper (II) nitrate trihydrate salt as a precursor. The structural properties, crystallinity, purity, morphology, and the chemical composition of as-synthesized CuO NPs were analyzed using different analytical methods. The analytical results revealed that the synthesized CuO was observed as spherical-like in particles with measured sizes ranging from 85–140 nm and has monoclinic crystalline phase with good purity. The Fourier transform infrared (FTIR) spectroscopic results confirmed the formation of the Cu-O bond through the involvement of the potential functional groups of biomolecules in papaya peel extract. Regarding photocatalytic activity, the green-synthesized CuO NPs were employed as a photocatalyst for the degradation of palm oil mill effluent (POME) beneath the ultraviolet (UV) light and results showed 66% degradation of the POME was achieved after 3 h exposure to UV irradiation. The phytotoxicity experiment using mung bean (Vigna radiata L.) seed also showed a reduction of toxicity after photodegradation.

Highlights

Due to the high demand for economical, nutritional, and edible vegetable oil, the palm oil industry has become one of the fast-growing industries in the world
We investigated the use of the water extract of waste papaya peel as reducing and stabilizing agents for the synthesis of copper oxide nanoparticles (CuO NPs)
The organic pollutant efficiencies these results indicated that green-synthesized CuO NPs have good photocatalytic activity to the reduce phytotoxicity of industrial wastewater

Summary

Introduction

Due to the high demand for economical, nutritional, and edible vegetable oil, the palm oil industry has become one of the fast-growing industries in the world. Malaysia has become the second largest palm oil producer in the world after Indonesia since 2006 and the palm oil industry is vigorously contributing to this country’s economy. The palm oil industry is generating a large amount of brownish colloidal liquid waste known as palm oil mill effluent (POME) and previous research studies suggest that 0.5–. POME is typically acidic (pH 4.5–5) with 95–96% water, 4–5% total solids including 2–4%. POME contains organic matters such as lignin (4700 ppm), phenolics (5800 ppm), pectin (3400 ppm), and amino acids [3]. POME can cause a severely destructive impact on the environment if discharged directly to water sources owing to its high chemical oxygen

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