WO₃/Nb₂O₅ Nanoparticles-Decorated Hierarchical Porous ZnO Microspheres for Enhanced Photocatalytic Degradation of Palm Oil Mill Effluent and Simultaneous Production of Biogas

Abstract:

Conventionally, palm oil mill effluent (POME) was treated using open ponding system, which nevertheless long retention times and large treatment areas were required. In this report, heterogeneous photocatalysis was used to degrade the POME and simultaneously assessed the biogas formation. Characterization of the chemically prepared hierarchical porous ZnO microspheres showed that wurtzite was the predominant crystalline phase with a band gap energy of 3.22 eV. Moreover, the as-prepared ZnO were assembled by large numbers of interleaving nanosheets and formed an open porous structure. Under UV irradiation, the as-prepared ZnO demonstrated photocatalytic property on POME degradation. The WO₃ and Nb₂O₅ decorated ZnO photocatalysts (WO₃/ZnO and Nb₂O₅/ZnO) with improved photocatalytic performances were also prepared using a simple and rapid way. Significantly, in the presence of WO₃/ZnO and Nb₂O₅/ZnO composites, the degradation of POME achieved 68.3% and 91.7%, respectively after 240 min irradiation. Interestingly, the assessment of the biogas formation showed that the photocatalytic reactions over Nb₂O₅/ZnO and WO₃/ZnO composites generated higher amount of biogas products (CH₄ + CO₂) compared to that of ZnO. The photocatalytic enhancement was attributed to the high separation efficiency of photogenerated electron–hole pairs based on the formation of heterojunction structures between the WO₃/Nb₂O₅ and ZnO. The observed findings also revealed that the photocatalytic technology using hierarchical WO₃/ZnO and Nb₂O₅/ZnO composites had the potential to efficiently treat wastewater.

• Periodical: Key Engineering Materials (Volume 821)
• Pages: 379-385
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.821.379
• Online since: September 2019
• Authors: Jin Chung Sin*, Ying Hui Chin, Sze Mun Lam
• Keywords: Biogas, Nb₂O₅, Palm Oil Mill Effluent, Photocatalysis, WO₃, ZnO

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