Microwave- and Formaldehyde-Assisted Synthesis of Ag–Ag₃PO₄ with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B Dye and Crude Oil Fractions

Abstract

The release of crude oil and water-soluble dyes into our marine environment is a major global problem. An efficient semiconductor Ag–Ag3PO4 photocatalyst was synthesized using formaldehyde as a reducing agent to form surface active Ag on Ag3PO4 under microwave radiation for heating, and its potential in destroying environmental pollutants has been examined. The diffuse reflectance spectroscopy of Ag–Ag3PO4 revealed an enhanced absorption in the visible light region. The rate of photocatalytic degradation of rhodamine B by Ag–Ag3PO4 was over 4-fold compared to Ag3PO4. The potential application of Ag–Ag3PO4 in oil spill remediation was also examined through photocatalytic degradation of benzene, n-hexane, and 1:1 v/v benzene/methanol crude oil-soluble fractions. UV–vis and gas chromatography–mass spectrometry analysis of the crude oil components after visible light irradiation showed excellent degradation. The photocatalytic efficiency enhancement of Ag–Ag3PO4 is attributed to the excellent electron trapping of silver nanoparticles deposited on the surface of Ag3PO4. This work will motivate future studies to develop recyclable visible light photocatalysts for many applications.

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

“…A calculated amount of AgNO 3 was added to the dispersed TiO 2 to obtain different weight percentages of Ag on TiO 2 . Based on the result of a previous work by Nyankson et al [19], 8 ml of formaldehyde was added to the resulting solution of the dispersed TiO 2 and microwaved for 6 min. The microwaved solution was allowed to cool and centrifuged at 6000 rpm for 10 min.…”

“…The potential of photocatalytic reactions to replace these conventional processes is particularly promising. For example photocatalytic reactions have been investigated for the production of hydrogen gas [5], dye degradation and oil-water emulsion separation [6], air purification or CO 2 photo-reduction and for pharmaceutical and agro-based waste treatment. Photocatalytic reactions have a high oxidation and reduction potential which allows for complete degradation of organic pollutants [7].…”

“…Several techniques have been employed to overcome these challenges and these include dye sensitization and addition of non-metal ions [6], coupled semiconductor system [9], coating with transition metals [10] and noble metal loading [11,12]. While all of these techniques have been reported to greatly increase the photocatalytic efficiency of TiO 2 , the use of noble metal-TiO 2 photocatalyst instead of the conventional TiO 2 has gained a lot of attention over recent years [13].…”

Investigating the photocatalytic role of Ag3PO4 and CdS composites based on CNTs to degrade methyl orange under visible light

“…The conduction band energy in silver phosphate is 0.45 eV, which is greater than the reduced potential of H 2 O/H 2 and makes water weak in trapping electrons produced by light. Thus, the produced electrons are absorbed by Ag + and then are released from the Ag 3 PO 4 crystal lattice, leading to the photocorrosion of silver phosphate 18‐20 . Not only does this phenomenon disrupt the structure of silver phosphate, but it also greatly reduces light absorption, which significantly reduces the photocatalytic activity of the semiconductor.…”

“…Thus, the produced electrons are absorbed by Ag + and then are released from the Ag 3 PO 4 crystal lattice, leading to the photocorrosion of silver phosphate. [18][19][20] Not only does this phenomenon disrupt the structure of silver phosphate, but it also greatly reduces light absorption, which significantly reduces the photocatalytic activity of the semiconductor.…”