The effect of synthesis route on the photocatalytic performance of Ag-TiO₂ using rhodamine b dyes, pesticides, and pharmaceutical waste as model pollutants

Abstract

The use of noble metal loading such as Ag to improve the photocatalytic performance of TiO2 has been well studied. Though different synthesis methods have been used to synthesize Ag-TiO2 nano-composite, the effect of the different synthesis routes on the photocatalytic performance has not been studied and compared. This study focusses not only on the enhancement of photocatalytic performance by the addition of Ag, but also on the influence of the synthesis process on photocatalytic performance. Two different routes: photodeposition (PD) and formaldehyde assisted microwave (MW) synthesis of Ag-TiO2 nano-composite and their photocatalytic performance were evaluated using model pollutants. The Ag-TiO2 were synthesized using different wt.% (0.5, 1.0, 1.5 and 2.0 wt.%) of Ag. The synthesized Ag-TiO2 were characterized with x-ray diffractometer, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and UV-vis spectrophotometry. The Ag-TiO2 photocatalyst showed superior photocatalytic performance towards rhodamine b dye as compared to raw TiO2. 0.5 wt.% Ag-TiO2-PD recorded the highest rate constant and degradation percent among the composites synthesized using photodeposition (PD) method. On the other hand, 1.0 wt.% Ag-TiO2-MW performed better among the composites synthesized using microwave and formaldehyde assisted synthesis. The potential of these best performing composites; 0.5 wt.% Ag-TiO2 and 1.0 wt.% Ag-TiO2 to photocatalytically degrade pharmaceutical (Naproxen Sodium and Flurbiprofen) and pesticide (Atrazine and Pyrimethanil) pollutants were examined. These composites degraded the pollutants exceptionally well with 0.5 wt.% Ag-TiO2-PD outperforming the 1.0 wt.% Ag-TiO2-MW. 1H NMR and 13C NMR analysis revealed that the synthesized Ag-TiO2 were effective in degrading the model pollutants.

Photocatalytic Degradation of Tetracycline Hydrochloride by Mn/g-C3N4/BiPO4 and Ti/g-C3N4/BiPO4 Composites: Reactivity and Mechanism

“…The g-C3N4 was prepared by calcining 20 g of melamine with high temperature muffle furnace at 550 °C; (1) Weighing a fixed ratio of TiO2, g-C3N4, Bi(NO3)3-5 NaH2PO4-2H2O, where the ratio of g-C3N4 and BiPO4 masses was a constant 1:5, chan only the mass fraction ratio of TiO2 in the catalyst [40]. Deionized water was added fo trasonic stirring, followed by washing the solution in small amounts into the Teflon b (the solution in the bottle did not exceed 80% of the total capacity of the Teflon bottle Subsequently it was placed in a hydrothermal reactor for 8 h at 160°; after extraction, dr and grinding to obtain 5 wt%, 7.5 wt%, 10 wt%, 12.5 wt%, 15 wt%, and 17.5 wt% Ti-BPC Weigh an appropriate amount of g-C3N4 and add an appropriate amount of Bi(NO3)3-5 with NaH2PO4-2H2O with ultrasonic stirring to form suspension; subsequently placed hydrothermal reactor at 160° for 6 h [42]; the precursor complex g-C3N4/BiPO4 was obta as a white solid, an appropriate amount of MnCl2 dissolved in deionized water was ad the mixed solution was poured into the autoclave, sealed and compacted in an oven at for 8 h; 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and 30 wt% of Mn-BPC, respectively.…”

“…(2) Weigh an appropriate amount of g-C 3 N 4 and add an appropriate amount of Bi(NO 3 ) 3 -5H 2 O with NaH 2 PO 4 -2H 2 O with ultrasonic stirring to form suspension; subsequently placed in a hydrothermal reactor at 160 • for 6 h [42]; the precursor complex g-C 3 N 4 /BiPO 4 was obtained as a white solid, an appropriate amount of MnCl 2 dissolved in deionized water was added, the mixed solution was poured into the autoclave, sealed and compacted in an oven at 160 • for 8 h; 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and 30 wt% of Mn-BPC, respectively.…”

Multicomponent Photocatalytic-Dispersant System for Oil Spill Remediation

“…Another major limitation of dispersants is their inability to remediate the water-soluble components of crude oil in the marine environment. The observation over the years is that water-soluble portions of hydrocarbons from spilled oil stay in the marine ecosystem for several years, wreaking damaging effects on the oceans with a causal sequence on the economy and well-being of the inhabitants in the areas where crude oil spill occurs. ,− On the other hand, the effectiveness of photocatalysis in degrading pollutants that are water-soluble, such as dyes, pesticides, and pharmaceutical wastes has been reported. − …”

“…In Ghana, for instance, the daily solar irradiation varies between 4 and 6.5 kWh/m 2 /day, emphasizing the advantage of optimizing TiO 2 for utilization of this valuable resource. Furthermore, the presence of Ag nanoparticles on the TiO 2 surface acts as an electron sink, effectively capturing photogenerated electrons from the conduction band of the adjacent semiconductor, owing to the Fermi level gradient. , Numerous research studies have demonstrated the remarkable photocatalytic degradation capabilities of Ag-TiO 2 for various environmental organic pollutants. ,,,− In a recent study, Nyankson et al systematically explored the Ag composition in Ag-TiO 2 , revealing that the photocatalytic performance peaks with 0.5 wt % Ag incorporation . Ag-TiO 2 can be synthesized through various methods, including wet impregnation, sol–gel, coprecipitation, hydrothermal, and photo deposition techniques. − In our current research, we have chosen to employ the photodeposition method to modify TiO 2 with silver (Ag).…”