Synthesis and Characterization of Pure and Nano-Ag Impregnated Chitosan Beads and Determination of Catalytic Activities of Nano-Ag

Abstract

The synthesis of nano-Ag impregnated porous Chitosan beads, in crosslinked and uncrosslinked forms, was aimed to investigate their catalytic potential in reducing nitro group into amino by NaBH4. The material was found unique concerning the synthesis of well-defined Ag NPs and subsequently adsorbing them on its surface. The crosslinked and uncrosslinked chitosan beads were separately analyzed for the loading of Ag and its effect over the microstructures of the substrate. BET was used to explore the porous nature and pore size distributions of beads. At each stage, SEM coupled with EDX, FT-IR, and inductively coupled plasma (ICP) were employed to characterize the material. The catalytic activities of nano-Ag in crosslinked and uncrosslinked beads were determined by the reduction of 4-Nitrophenol (4-NP) into 4-aminophenol (4-AP) by NaBH4; which is least effective for such reduction. The catalytic activities were monitored by UV-Vis spectrophotometer. The results demonstrated the nano-Ag as a reliable and active catalyst which made NaBH4 quite capable for the nitro reduction. Moreover, the catalytic activities of crosslinked chitosan substrate were found more reproducible as compared to the uncrosslinked substrate.

Killing Two Birds with One Stone: Coating Ag NPs Embedded Filter Paper with Chitosan for Better and Durable Point-of-Use Water Disinfection

“…We suspect that this is because the abundant and uniformly distributed amino groups in CS coated on the paper provide an excellent adsorption capacity to combine with Ag (and hence prevent it from releasing into the treated water). 22,23 It was clear that the presence of Ag NPs significantly enhanced the antibacterial activity compared to pure paper (Figure 3). Figure 3 also shows that the bactericidal effect of the filter paper improved gradually with the increase in silver content.…”

“…However, even at this high level, the total Ag in the treated water was just about 45 μg/L, less than half of the WHO requirement (<100 μg/L). We suspect that this is because the abundant and uniformly distributed amino groups in CS coated on the paper provide an excellent adsorption capacity to combine with Ag (and hence prevent it from releasing into the treated water). , …”

Ag Nanostructure Morphologies and Physicochemical Properties Dictated by the Polyols Used in the Synthesis

“…The polyol process mainly employs ethylene glycol (EG) as a reducing agent for the synthesis of Ag NWs; it is also a suitable solvent for AgNO3 and PVP, due to its high polarity and dielectric constant [7][8][9]. Usually, an oxygen free environment is preferred to avoid oxidation of nanostructure [10,11].…”