Preparation of Silver Nanoparticles from Synthetic and Natural Sources: Remediation Model for PAHs

The emergence of nanoscience and technology is gaining popularity with an increasing demand for
metal nanoparticles applicability in various areas such as electronics, catalysis, chemistry, energy and
medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the
chemicals used are quite often toxic and flammable. In this work, an attempt is made to compare the
efficiency of two different synthesis methods and application of each for the remediation of poly
aromatic hydrocarbons (PAHs). In this regard, silver nanoparticles are prepared by green and wet
chemical method using plant extract of garlic (Allium sativum). The extract is known to reduce the
metal during synthesis and acts as stabilizing ligand. These synthesized silver nanoparticles (Agp)
and (AgW) were applied as adsorbents in synthetic batch mode experiments at varying parameters of
pH and temperature. A concentration of 0.01 mg/L of Phenanthrene, Anthracene, and Pyrene were
induced at fixed dosage of 1mg/Kg of adsorbent. Residual concentration of each PAH was analyzed
on UV- Visible spectrophotometer. The results indicated that both adsorbents follow the sequence of
Phenanthrene>Pyrene>Anthracene with optimal removal of higher than 85% in each case. A
distinguishing privilege is attained by Agp adsorbent showing 3, 3 and 11 orders of magnitude higher
efficiency than Agw. It may be attributed to more functional groups in the plant extract participating in
binding of PAH to the surface. Each synthesized adsorbents was characterized by FTIR, SEM and
EDX. The average particle size was determined to be of the order of 13-26 nm. The present study
offers a simple and convenient method of synthesis of nano-sized particles by using a low cost and
non-hazardous sodium hydroxide rather than toxic sodium borohydride as reducing agent. The
study concludes the use of alternate economical and green adsorbents for control of poly aromatic
hydrocarbons (PAHs). The study recommends the use of alternate economical and green natural
adsorbents for control of poly aromatic hydrocarbons (PAHs).