Silver Nanoparticle Synthesis and Purification

Silver Nanoparticle Water Purification

• Synthesis: Aqueous solutions of sodium borohydride (NaBH₄) and trisodium citrate (TSC) were mixed and heated to 60°C for 30 minutes in the dark.
• AgNO₃ addition: Aqueous silver nitrate (AgNO₃) solution was gradually added to the mixture.
• Temperature increase: The temperature was subsequently raised to 90°C.
• pH adjustment: The pH of the solution was adjusted to 10.5 using 0.1 M NaOH while heating continued for 20 minutes.
• Cooling: The nanoparticle suspension was allowed to cool to room temperature.
• Unreacted removal: Unreacted reductants were removed by centrifuging the AgNP suspensions at 12,000 rpm for 15 minutes, followed by three washes.
• Redispersion and storage: The nanoparticles were redispersed in deionized water (DI water) and stored at 4°C.

Nanoparticle Stages

• Stage I: Silver ions (Ag⁺) undergoing instant nucleation to form Ag⁰ nuclei, followed by coalescence into clusters.
• Stage II: Citrate reduction at pH 10.5 leads to homogeneous growth of the silver nanoparticles.
• Final product: Citrate-stabilized silver nanoparticles.

Characterization

• UV-Vis Spectroscopy: Extinction spectra were acquired to determine the size of nanoparticles. The study varied sizes from 5 nm to 100 nm.
• Visual Observation (Images): The study included colored solutions corresponding to different nanoparticle sizes. Images confirm the color change related to varying sizes of synthesized nanoparticles.
• Transmission Electron Microscopy (TEM): TEM images were taken to showcase the nanoparticle morphology with magnification levels, showing 100 nm and 200 nm levels.
• Zeta potential: A zeta potential plot of the silver nanoparticles was acquired and plotted.
• FTIR Spectroscopy: Fourier transform infrared spectra (FTIR) illustrated the presence of citrate bonds. The wavenumbers were identified to reveal the specific chemical bonds involved.

This quiz covers the detailed process of synthesizing silver nanoparticles (AgNPs) for water purification. It includes steps such as the mixing of solutions, temperature adjustments, pH modifications, and unreacted removal techniques. Assess your understanding of each stage involved in the nanoparticle production and their implications for water treatment.