Abstract
Zero valent arsenic nanoparticles (As(0)) in two different size ranges such as 55 ± 8 and 61 ± 9 nm were prepared by reducing As(III) using NaBH4, and designated as As1 and As2. Galvanic replacement reaction (GRR) of As(0) was employed for the synthesis of Ag nanoparticles (AgNPs) in two different size ranges. The as-prepared AgNPs i.e. AgNP1 and AgNP2 were then converted to heterogeneous catalyst by adsolubilizing them onto surfactant-modified silica (SMS) surface, and the immobilized AgNPs were designated as Ag1-SMS and Ag2-SMS, respectively. The AgNPs thus formed in both homogeneous and heterogeneous phases were utilized as catalyst for 4-nitrophenol (4-NP) reduction in borohydride medium. The homogeneous catalysts were found to be more efficient compared to the supported catalysts. As for example, the complete reduction of 4-NP using homogeneous Ag(0) catalyst was achieved within 12 min with a first order rate constant of 0.1513 min−1 using AgNP1 at a dose of 1.86 mg/L. On the other hand, when it was immobilized on SMS surface it showed a rate constant 0.0259 min−1 at a dose of 9 mg/L. The size effect of the AgNPs was also realized in both homogeneous and heterogeneous catalytic reactions. At a constant catalyst dose (in terms of Ag), smaller sized particles showed higher reaction rate compared to the larger particles. The TON and TOF as calculated for all the catalysts showed that homogeneous AgNPs were more efficient (>24 times) than the AgNPs when they are immobilized on SMS surface.
Original language | English |
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Article number | 126579 |
Journal | Materials Chemistry and Physics |
Volume | 290 |
DOIs | |
State | Published - 15 Oct 2022 |
Externally published | Yes |
Keywords
- 4-NP catalytic Reduction
- Arsenic zero nanoparticles
- Galvanic replacement reaction
- Immobilization of AgNPs on solid surface
- Silver nanoparticles
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics