ORIGINAL RESEARCH
Activated Carbon-Supported Palladium Nanoparticles: Synthesis Via Different Reducing Agents and Antibacterial Applications
 
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1
Chemistry Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123, Muscat, Oman
 
2
Biology Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123, Muscat, Oman
 
3
Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123, Muscat, Oman
 
4
College of Medicine, Pathology Department, College of Medicine and Health Science, Sultan Qaboos University, P.O. Box 35, Muscat 123, Oman
 
5
CAARU Center, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123, Muscat, Oman
 
 
Submission date: 2026-02-22
 
 
Final revision date: 2026-05-23
 
 
Acceptance date: 2026-06-19
 
 
Online publication date: 2026-09-18
 
 
Corresponding author
El-Said Ibrahim El-Shafey   

Chemistry Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123, Muscat, Oman
 
 
 
KEYWORDS
TOPICS
ABSTRACT
This study compares a green reducing agent (ascorbic acid, AA) with chemical reducing agents (borohydride, BH, and hydrazine hydrate, HH) for the immobilization of Pd0 nanoparticles (NPs) onto activated carbon to evaluate their antibacterial properties. The activated carbon prepared from black cumin seeds was used as a substrate on which Pd nanoparticles (Pd NPs) were deposited in situ using the three reducing agents. The reducing agents were used over a concentration range of 2-10 mM at 20ºC. The Pd(0) loading was 45.4±0.5 (mg/g), 45.2±0.4 (mg/g), and 39.9±1.9 (mg/g) for BH, AA, and HH, respectively, when different amounts of reducing agents were used. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) showed the presence of Pd NPs in different crystallite sizes, particle sizes, and morphologies. Pd particles produced by BH reduction were larger than those reduced by HH or AA. Crystallite size decreases as the concentration of the reducing agent increases for BH and AA, while with the increase in HH concentration, a slight increase in the average crystallite size was observed. The antibacterial efficacy against S. aureus, B. cereus, and E. coli was qualitatively assessed by inhibition zone size and quantitatively by turbidity. Growth inhibition zones for reduced Pd nanoparticles follow the order: AA>HH>BH. For the quantitative turbidity method, growth inhibition showed efficient antibacterial results for Pd NPs reduced by AA and HH more than those reduced by BH. This can be attributed to their smaller particle size compared with those reduced by BH.
CONFLICT OF INTEREST
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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