Department of Physics, Faculty of Science UPM
PROF. DR. AZMI ZAKARIA , DR. REZA ZAMIRI
In this project we used a laser ablation technique for preparation of silver nanoparticles. The fabrication process was carried out by ablation of a silver plate immersed in palm oil. A pulsed Nd:YAG laser at a wavelength of 1064 nm was used for ablation of the plate at different times. The palm oil allowed formation of nanoparticles with very small and uniform particle size, which are dispersed very homogeneously within the solution. The obtained particle sizes for 15 and 30 minute ablation times were 2.5 and 2 nm, respectively. Stability study shows that all of the samples remained stable for a reasonable period of time.
UV-visible absorption spectra of samples containing Ag-NPs prepared for different ablation times in palm oil.
A big challenge in the synthesis of NPs is agglomeration. Much effort has been undertaken to develop different ligands as colloidal stabilizers. Recently, synthesis of NPs using fatty acids (oleic and lauric acid) as stabilizers has been reported. These organic compounds are amphiphilic molecules with polar carboxylic group, which is able to coordinate to NPs and non polar long carbon chains that prevent NPs agglomeration through steric repulsion. Palm oil contains palmitic 44.3%, stearic 4.6%, myristic 1%, oleic 38.7% and linoleic 10.5%. The presence of long hydrocarbon chains and polar ester bond make it a good choice for stabilizing NPs.
For the preparation of Ag-NPs, we irradiated the metal silver plate in palm oil by laser under different irradiation times (5, 10, 15, and 30 min). As shown in Figure, the metal plate (>99.99%) was placed in a glass cell which was filled with a 10 mL of palm oil. A laser beam was focused on the silver target using a lens with focal length of 250 mm. During the ablation process the solution was stirred magnetically to disperse the produced NPs. The laser output power was 360 mJ/pulse.
The mechanism of the adsorption and capping of Ag-NP by palm oil can be explained through coordination of carbonyl bond that means electron transfer from C=O to Ag-NP. On the other hand, the long chain hydrocarbons prevent NPs agglomeration by steric repulsions. The motion of adsorbed molecules will be restricted in the interparticle space, which leads to the stability of particles.
TEM images and typical of statistical graphs for Ag-NPs in palm oil under (a) 15 and (b) 30 min ablation times.
Reza Zamiri, Azmi B.Z, Abbastabar A.H, Sadrolhosseini A.R. and Mahdi M.A. (2010). Fabrication of silver nanoparticles dispersed in palm oil using laser ablation. Int. J. Mol. Sci, 11, 4764-4770 . Reza Zamiri, Azmi B.Z, Darroudi M, Sadrolhosseini A.R, Husin M.S, Wahab, Z.A. and Mahdi M.A. (2011). Preparation of starch stabilized silver nanoparticles with spatial self-phase modulation properties by laser ablation technique. Appl. Phys. A, 102, 189-194. Reza Zamiri, Azmi B.Z, Abbastabar H, Darroudi M and Mahdi M. (2011). Laser fabricated castor oil capes silver nanoparticles. Int. J. Nanomed, 6, 565–568. Reza Zamiri, Azmi B.Z, Sadrolhosseini A.R, Zaidan A.W and Mahdi, M.A. (2011). Preparation of silver nanoparticles in virgin coconut oil using laser ablation. Int. J. Nanomed, 5, 75-77.
Schematic representation of steric stabilization of Ag-NP
RESEARCHER INFORMATIONS: Commercialize - Contact: Prof. Dr. Azmi Zakaria Director Department of Physics, Innovation and Commercialization Center (ICC) Faculty of Science, UPM University Putra Malaysia 43400 UPM Email :azmizak@fsas.upm.edu.my Serdang, Selangor, Malaysia Tel : 03-89466650 Tel : +603-8947 2055/ 2056/ 2057/ 2058 Fax : 03-89454454 Email : komersil@icc.upm.edu.my