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Shape, size, and homogeneity affect the biological activity of gold nanoparticles (AuNPs) in nanomedicine and catalytic applications. Here we biosynthesized monodispersed isotropic and polydispersed anisotropic spherical AuNPs from leaf and seed extract broths of the medicinal plant Peganum harmala L. (Ph. L). Synthesized AuNPs were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IRS), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The antimicrobial activity of AuNPs against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) human pathogens was also assessed. Leaf-and seed-derived AuNPs had characteristic localized surface plasmon resonances of 530 and 578 nm, respectively. TEM, FE-SEM, EDX, and XRD revealed the formation of elemental face-centered cubic spherical monodispersed isotropic AuNPs of average size 43.44 nm and polydispersed anisotropic AuNPs of average size 52.04 nm from leaf and seed extract broths, respectively. FT-IR revealed polyphenols and alcohols as responsible for AuNP capping, reduction, and protection. Anisotropic AuNPs showed no antibacterial activity, whereas isotropic AuNPs showed good inhibition of both E. coli and S. aureus. This represents a simple and ecofriendly protocol for the green synthesis of monodispersed isotropic spherical AuNPs, which may have value in a variety of applications.

This paper investigated the production of alumina from Nawan kaolin by acid leaching with sulfuric and hydrochloric acids. Kaolin was calcined at 850°C and was leached with 6 M acid at 90°C, 5M NaOH followed by HCl solutions were added to the leaching liquor, and the precipitated aluminum hydroxide was converted to alumina by calcination at 900°C. Materials were characterized by FTIR, XRD, and SEM techniques. The alumina extraction percent was determined at different leaching times (30-180 min) and solid/liquid ratios (0.05-0.15 g/ml). The purity of kaolin is about 95%. The percent of extraction of alumina rapidly increases with the solid/liquid ratio up to 0.1 g/ml then decreases thereafter. The percent of extraction of alumina is higher for HCl than H2SO4. The size of the chloride and sulfate ions is the key factor that controls the percent of extraction of alumina from calcined kaolin under the studied conditions.

The magnetic treatment devices for water have been in use for scale prevention several decades ago. Although, the effect of magnetic treatment on the chemical and physical properties of water is not fully understood and needs to make a lot of research effort to be clarified. This work aims to investigate the effect of the magnetic treatment on the temporary hardness of the groundwater. A sample of groundwater was passed twice under the influence of perpendicular magnetic strength 0.5 Tesla with a flow rate of 10 L/h. The temporary and permanent hardness as well as scale formation test were measured before and after the magnetic treatment. The scale was analyzed by XRD and SEM techniques. The temporary hardness and the weight of scales were reduced after the magnetic treatment by 39.1 and 22.3 %, respectively. The decrease of temporary hardness after the magnetic treatment of groundwater may be attributed to that the magnetic field reduces both the dissolved CO2 content and surface tension, both of which reduce the amount of temporary hardness. The SEM micrographs illustrate that the magnetic treatment modified the shape and size of crystals of CaCO3 scales to prevent its adhesion to the substrate forming hard scales. The XRD patterns prove that the magnetic treatment of groundwater enhances the crystallization of amorphous CaCO3 favouring the formation of calcite.

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