Photocatalytic removal of pollutants from water using graphitic carbon nitride-based photocatalysts

Ahmad, Noman (2025) Photocatalytic removal of pollutants from water using graphitic carbon nitride-based photocatalysts. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (2MB)

Abstract

This thesis comprises of two main sections. The first part discusses the degradation of nitenpyram using g-C₃N₄ nanosheets and the second part converse the dual functional photocatalysis which involves the simultaneous reduction of Chromium (VI) and oxidation of nitenpyram from water using g-C₃N₄/WO₃ heterojunction. Firstly, the g-C₃N₄ nanosheets were prepared by two step calcination process of melamine in muffled furnace. The characterization results of the prepared nanosheets showed enhanced visible light harvesting ability, narrow band gap and increased surface area compared with the bulk g-C₃N₄ increasing the overall efficiency of the photocatalyst. The nanosheets were utilized as a photocatalyst under visible light to degrade nitenpyram from water. All these experiments were carried out in a batch reactor with a light source for visible light photocatalytic reactions. The results show that it can degrade 99% of the nitenpyram with an initial concentration of 10 ppm at pH 9.0 and catalyst dosage of 1.0 g/L. Further analysis indicates the successful degradation of nitenpyram into its metabolites CPMF, and CPF. Secondly the nanosheets were combined with metal oxide WO₃ to form a heterojunction which can be used as a dual process for reduction of chromium (VI) and degradation of nitenpyram (NTP). Characterization results show that it has narrower band gap, suitable valance and conduction bands positions, reduced recombination rate of electron-hole pairs which increases its photocatalytic ability for the redox reaction. The experimental outcomes display that it can efficiently reduce chromium (VI) and degrade nitenpyram under visible light. For the dual process at pH 3.0, catalyst dosage of 1.0g/L and initial concentration of 20 ppm the chromium (VI) reduced 88.75% and nitenpyram (NTP) degraded 91.6%. The performance of the heterojunction is compared with the nanosheets and WO3 which shows a considerable increase in removal of pollutants from environment. The band positions of g-C₃N₄ and WO₃, as determined from UV- DRS, indicate the formation of a Type II heterojunction between the two semiconductors. This configuration significantly enhances the separation of photogenerated electrons and holes, thereby improving the reduction efficiency of chromium (VI) and the degradation efficiency of nitenpyram (NTP).

Actions (login required)

View Item