Modification of pg-C3N4 for photocatalytic degradation of methylene blue under visible light irradiation
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Date
2019-06
Authors
Devaraja Jegathisan
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Abstract
Wastewater pollution give a negative impact to environment and living organisms. Various pollutant removal techniques were found such as adsorption, biodegradation, photodegradation and electrochemical oxidation. Advanced Oxidation Processes (AOPs) are also developed to treat pollutants found in water. Such processes are Fenton processes, ozonation, and photocatalysis. Among them, photocatalysis using g-C3N4 photocatalyst have attracted considerable attention in recent years. Bulk g-C3N4 (BCN) being a metal free catalyst, have smaller band gap, but have higher electron-hole pair recombination rate and lower porosity. Therefore, several modifications have been made to improve the photocatalytic performance of BCN. The porous g-C3N4 was synthesized by mechanically mixing of melamine and urea at different composition (0, 30, 50, 70, 90 wt% urea). The as-prepared pg-C3N4 then further modified with different composition of ZnO to further increase the photocatalytic performance (5, 10, 15, 20 wt% ZnO) by ultra-sonication method. Characterization studies such as SEM-EDX, FTIR and BET surface area measurement were done on BCN, 90U pg-C3N4 and 15 wt% ZCN. The SEM results shows that the mixing of urea with melamine have huge influence over its surface morphology, forming nanotubes. Further modification with ZnO resulted in formation of aggregates and wrapping by pg-C3N4. The FTIR study shows the similar spectra for the three photocatalyst, indicating the similar chemical bonds presented. The BET results further proves the high surface area and porosity of the modified catalysts. The photocatalytic performance of as-prepared photocatalysts was evaluated for degradation of Methylene Blue (MB). The photocatalyst 15 wt% ZCN exhibited the highest photocatalytic performance with 85.47% removal after 3h irradiation.