Effects of annealing time on the structure and optical properties of ZnAl2O4/ZnO prepared via citrate sol-gel process

ZnAl2O4 nano-powders have been successfully prepared via citrate sol-gel technique. All powder samples were annealed at 600 °C for 1, 2, and 3 h. Thermogravimetric analysis (TGA) confirmed that the minimum annealing temperature of crystallization is ∼400 °C. Fourier Transform Infrared (FTIR) results showed a series of absorption peaks in the range of 810–4000 cm−1. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) results showed that the prepared nano-crystals consists of the mixture of both cubic (ZnAl2O4) and hexagonal (ZnO) structures. Ultra violet visible (UV–vis) spectroscopy revealed that the annealing time (AT) influences the band gap of the prepared phosphor materials. When the samples were excited at 275 nm, two emission peaks at 428 nm (violet) and 561 nm (green-yellow) were observed and they are attributed to the defects levels within the ZnO and ZnAl2O4 band gaps. The Commission Internationale de l’Elcairage (CIE) colour coordinates confirmed that all the prepared samples exhibit the violet emission and varying the AT does not influence the emission colour.The South African National Research Foundation (NRF) Thuthuka Programme (fund number: UID99266).https://www.elsevier.com/locate/mtcomm2019-03-01hj2018Physic

Associated aspects on structure, morphology and photoluminescence of MgAl2O4:x% Gd3+ nanophosphor prepared via citrate sol-gel method

Please read abstract in the article.The South African National Research Foundation (NRF) Thuthuka Programme (Fund No: UID99266) and NRF incentive funding for rated researchers (IPRR) (Grant No: 114924).http://link.springer.com/journal/116642020-06-01hj2019Physic

Biodiesel Production from Waste Oils: A South African Outlook

The viability of large-scale biodiesel production ultimately boils down to its cost of commercialisation despite other very important factors such as the negative environmental and health effects caused by the direct combustion of fossil diesel. How much each country’s economy will be influenced by the production of biodiesel will be determined by the commitment of various stakeholders to the much-needed transition from petroleum-based resources to renewable resources. Biodiesel production is largely determined by the cost of the feedstock (>70%) and this review focuses on the use of waste oil resources as biodiesel feedstock with a special focus on waste cooking oil (WCO). Generating value from waste oil provides an alternative waste management route as well as a positive environmental and economic contribution. The transesterification process for biodiesel production, its catalysis and some important technical and economic aspects are covered in this communication with a special focus on the South African framework. An overview of the current research and its implications going forward is discussed

Biodiesel Production from Waste Oils: A South African Outlook

The viability of large-scale biodiesel production ultimately boils down to its cost of commercialisation despite other very important factors such as the negative environmental and health effects caused by the direct combustion of fossil diesel. How much each country’s economy will be influenced by the production of biodiesel will be determined by the commitment of various stakeholders to the much-needed transition from petroleum-based resources to renewable resources. Biodiesel production is largely determined by the cost of the feedstock (>70%) and this review focuses on the use of waste oil resources as biodiesel feedstock with a special focus on waste cooking oil (WCO). Generating value from waste oil provides an alternative waste management route as well as a positive environmental and economic contribution. The transesterification process for biodiesel production, its catalysis and some important technical and economic aspects are covered in this communication with a special focus on the South African framework. An overview of the current research and its implications going forward is discussed