RESUMO
This study marks a pioneering effort in utilizing Vachellia tortilis subsp. raddiana (Savi) Kyal. & Boatwr., (commonly known as acacia raddiana) leaves as both a reducing and stabilizing agent in the green "eco-friendly" synthesis of silver nanoparticles (AgNPs). The research aimed to optimize the AgNPs synthesis process by investigating the influence of pH, temperature, extract volume, and contact time on both the reaction rate and the resulting AgNPs' morphology as well as discuss the potential of AgNPs in detecting some heavy metals. Various characterization methods, such as UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), Zeta sizer, EDAX, and transmitting electron microscopy (TEM), were used to thoroughly analyze the properties of the synthesized AgNPs. The XRD results verified the successful production of AgNPs with a crystallite size between 20 to 30 nm. SEM and TEM analyses revealed that the AgNPs are primarily spherical and rod-shaped, with sizes ranging from 8 to 41 nm. Significantly, the synthesis rate of AgNPs was notably higher in basic conditions (pH 10) at 70 °C. These results underscore the effectiveness of acacia raddiana as a source for sustainable AgNPs synthesis. The study also examined the AgNPs' ability to detect various heavy metal ions colorimetrically, including Hg2+, Cu2+, Pb2+, and Co2+. UV-Vis spectroscopy proved useful for this purpose. The color of AgNPs shifts from brownish-yellow to pale yellow, colorless, pale red, and reddish yellow when detecting Cu2+, Hg2+, Co2+, and Pb2+ ions, respectively. This change results in an alteration of the AgNPs' absorbance band, vanishing with Hg2+ and shifting from 423 to 352 nm, 438 nm, and 429 nm for Cu2+, Co2+, and Pb2+ ions, respectively. The AgNPs showed high sensitivity, with detection limits of 1.322 × 10-5 M, 1.37 × 10-7 M, 1.63 × 10-5 M, and 1.34 × 10-4 M for Hg2+, Cu2+, Pb2+, and Co2+, respectively. This study highlights the potential of using acacia raddiana for the eco-friendly synthesis of AgNPs and their effectiveness as environmental sensors for heavy metals, showcasing strong capabilities in colorimetric detection.
RESUMO
Environmental pollution is a critical issue due to its impact on humans and other organisms. An important demand nowadays is the need for a green method to synthesize nanoparticles to remove pollutants. Therefore, this study focuses for the first time on synthesizing the MoO3 and WO3 nanorods using the green and self-assembled Leidenfrost method. The XRD, SEM, BET and FTIR analyses were used to characterize the yield powder. The XRD results emphasize the formation of WO3 and MoO3 in nanoscale with crystallite sizes 46.28 and 53.05 nm and surface area 2.67 and 24.72 m2 g-1, respectively. A comparative study uses synthetic nanorods as adsorbents to adsorb methylene blue (MB) in aqueous solutions. A batch adsorption experiment was performed to investigate the effects of adsorbent doses, shaking time, solution pH and dye concentration to remove MB dye. The results demonstrate that the optimal removal was achieved at pH 2 and 10 with 99% for WO3 and MoO3, respectively. The experimental isothermal data follow Langmuir for both adsorbents with a maximum adsorption capacity of 102.37 and 151.41 mg g-1 for WO3 and MoO3.