Green synthesis of silver nanoparticles using Hibiscus sabdariffa leaves extract

The present paper reports the synthesis of silver nanoparticles (Ag-NPs) by a green method using Hibiscus sabdariffa (H. sabdariffa) leaves extract as reductant and stabilizer. The synthesized Ag-NPs were characterized by ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). UV-vis spectrum of synthesized Ag-NPs showed a peak at 378 nm. TEM analysis revealed that the particles were spherical and irregular in shape and has average size around 56.52 nm. This structure and size of particles were confirmed by AFM analysis. The UV-vis and FTIR spectrum provides evidence of the presence of caffeic acid component as a representative biomolecule in stabilising the nanoparticles based on previous studies. Hence, this study advocates that H. sabdariffa have potential for synthesizing nanoparticles

Preparation method of titanium dioxide nanoparticles and its application: an update

Titanium dioxide (TiO2) is widely used because of its good biocompatibility and stability. Various methods were used to prepare TiO2 by using chemical, biological, and physical methods. In this paper, the currents methods to prepare TiO2 were evaluated either with or without using plant extract. The average particle size produced for different methods of technique and its application was also analyzed. Chemical methods use toxic chemical while physical methods such as gamma produce high energy and using biological method with plant extract is more environmentally friendly. This review gives an up-to-date summary of TiO2 produced using various synthesis methods with the focus on their particle sizes properties. Recent publications on this topic were extracted from related journals obtained from Science Direct online database from the year 2010 to 2021. Preparation methods, average particles sizes, and the applications of the synthesized TiO2 were evaluated and further discussed in this review. It was found that TiO2 of smaller particle sizes were obtained when synthesized without using plant extract. Furthermore, many researchers tend to combine TiO2 with other materials or composites to be mixed with polymers for various purposes of application especially wastewater treatment application