University of South Africa

About: University of South Africa is a education organization based out in Pretoria, South Africa. It is known for research contribution in the topics: Context (language use) & Population. The organization has 8478 authors who have published 19960 publications receiving 237688 citations. The organization is also known as: Unisa.

Improved photocatalytic decomposition of aqueous Rhodamine-B by solar light illuminated hierarchical yttria nanosphere decorated ceria nanorods

Abstract: We report the new synthesis route of hierarchical yttria (Y2O3) nanosphere decorated ceria (CeO2) nanorods from the precursor cerium nitrate and yttrium nitrate under hydrothermal method (HM). Synthesized nanorods (NRs) were analyzed by different techniques to investigate their textural morphology, size and shape of nanorods and crystalline structures, morphology growth, optical activity and sizes of the samples. The luminescence blue peaks were observed in the range of 450–490 nm and green emission appeared at 533 nm at the room temperature (RT), the presence of oxygen vacancies was confirmed. The photodecomposition nature of the prepared nanosamples was investigated by using the industrial effluent Rhodamine-B (RhB) dye in aqueous medium by the illumination of solar light. The photocatalytic degradation efficiency showed 95.8% for RhB after 240 min. On illumination of visible light, the catalyst was found to tend to produce reactive oxygen species (ROS), which might account for the decay of dyes into small fractions. The enhanced photocatalytic effect of the synthesized NRs was primarily ascribed to the rising in the separation efficiency of electrons and holes.

Structures and molecular dynamics of plant waxes

Abstract: Waxes from the leaves of Fagus sylvatica L. (European beech tree) and Hordeum vulgare L. (barley) have been investigated using NMR, DSC, X-ray diffraction and gas chromatographic methods. The wax from Fagus sylvatica, consisting mainly of n-alkanals, n-alkanes and 1-alkanols, has chain-lengths ranging from 20 to 52 carbon atoms with an average chain-length of 30.5 carbon atoms. The X-ray results show that the wax is to a large extent (∼ 70%) amorphous. The wax from the leaves of Hordeum vulgare L., consisting mainly of n-alkanols, has chain-lengths ranging from 20 to 50 carbon atoms with an average chain-length of 27.4 carbon atoms. The wax is ∼ 52% crystalline. It seems that the structure of this wax differs from those of other plant waxes that have been investigated in that the longer chains bridge the amorphous zone between two adjacent layers of crystalline material, thus linking the two layers. This linking affects the melting point of the wax noticeably. The activation energies for the different molecular motions in these waxes have been extracted from the NMR spin-lattice relaxation time measurement.

Single-phase α-Cr2O3 nanoparticles’ green synthesis using Callistemon viminalis’ red flower extract

Abstract: This contribution reports for the first time on the synthesis and the main physical properties of single-phase pure α-Cr2O3 nanoparticles synthesized by a facile, rapid and eco-friendly process using Callistemon viminalis flower's extract as an effective oxidizing/reducing agent. These crystalline nanoparticles exhibit a cubic-like platelet shape with sharp edges with an average particle diagonal size of ∼92.2 nm. The room temperature physical properties of these pure highly crystalline Eskolaite α-Cr2O3 nanoparticles were carried out using complementary techniques such as high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), XRD, FTIR-ATR, Raman and XPS.