Photocatalytic efficiency of lanthanide-doped zinc oxide for degradation of methylene blue dye
2018
Mohd Sabri Mohd Ghazali | Wan Rafizah Wan Abdullah | Wan Mohd Norsani Wan Nik | Maishara Syazrinni Rooshde | Noradhiha Farahin Ibrahim
Photocatalytic treatment of dyeing wastewater using zinc oxide (ZnO) is a promising approach due to its economic viability, energy efficiency and environmental friendliness. In order to improve the environmental sustainability of existing photocatalysis based treatment technology, doping technique is performed on pristine semiconductor material to produce highly efficient photocatalyst. In this study, the potential use of lanthanide (Ce, Er, La and Pr) -doped ZnO as photocatalyst powder have been investigated for the degradation of methylene blue (MB) dye solution. Powder form photocatalyst was successfully prepared by doping ZnO at 1 mol % of lanthanides through combination of citrate gel and solid state means. The synthesized lanthanide-doped ZnO photocatalyst powder was characterised by using XRD, SEM and EDS. The photocatalyst of various loads (0.5 - 2.0 g/L) was used to induce photodegradation of 10 mg/L MB dye solution under UVlight illumination up to 180 minutes. The treated MB solution was characterized by using UV-Visible Spectrophotometer. The findings showed that the photocatalytic efficiency increased with the increase in catalyst loadings. The highest photocatalytic efficiency (94.32%) was achieved by treatment using 2.0 g/L of 1 mol % Er doped ZnO. The list of photocatalysts in the order of decreasing photocatalytic efficiency is Er doped ZnO (94.32%) > Ce doped ZnO (93.81%) > La doped ZnO (72.16%) > and Pr doped ZnO (67.67%). The Er and Ce doped ZnO based photocatalysts have proven efficiency to induce oxidation of organic dye in wastewater and they are indeed promising candidates for future solar-driven photocatalyst.
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