Nitrogen doped carbon nanotubes (N-CNTs) have become a topic of increased importance in the study of carbonaceous materials. This arises from the physical and chemical properties that are created when N is embedded in a CNT. These properties include modified chemical reactivity and modified conductivity and mechanical properties. A range of methodologies have been devised to synthesize N-CNTs. One of the procedures uses a floating catalyst in which an organometallic complex is decomposed in the gas phase in the presence of a nitrogen containing reactant to give N-CNTs. Most studies have been limited to ferrocene, ring substituted ferrocene and Fe(CO)5. This review covers the synthesis (and properties) of N-CNTs and other shaped carbon nanomaterials (SCNMs) produced using organometallic complexes. It summarizes the effects that physical parameters such as temperature, pressure, gas flow rates, type and concentration of N source etc. have on the N-CNT type, size and yields as well as the nitrogen content incorporated into the tubes that are produced from organometallic complexes. Proposed growth models for N-CNT synthesis are also reported.

Membrane distillation (MD) is a thermally driven process that uses low‐grade energy to operate and has been extensively explored as an alternative cost‐effective and efficient water treatment process compared to conventional membrane processes. MD membranes are synthesized from hydrophobic polymers, e.g. polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) or polypropylene (PP), using various methods including phase inversion and electrospinning techniques. Recent literature on MD membranes clearly shows their important role in surface water/wastewater treatment and seawater desalination. Modification of MD membranes with nanoscale materials significantly improves their performance, preventing wetting and fouling. This review presents a critical assessment of the progress on the use of nanomaterials for the modification of MD membranes. The techniques commonly used to synthesize MD membranes, the modifications that have been adopted for the incorporation of nanomaterials onto membranes, and the unique properties these nanomaterials impart on the membranes are discussed. The use of modified membranes in different MD configurations and their application in groundwater, surface water, wastewater, brackish water and seawater treatment is reviewed. Finally, cost implications, commercial viability, environmental sustainability, and future prospects of MD are also discussed to elucidate promising approaches for a future and successful implementation of MD at an industrial scale. © 2019 Society of Chemical Industry

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Materials made of carbon that can be synthesised and characterised at the nano level have become a mainstay in the nanotechnology arena. These carbon materials can have a remarkable range of morphologies. They can have structures that are either hollow or filled and can take many shapes, as evidenced by the well-documented families of fullerenes and carbon nanotubes. However, these are but two of the shapes that carbon can form at the nano level. In this review we outline the types of shaped carbons that can be produced by simple synthetic procedures, focusing on spheres, tubes or fibres, and helices. Their mechanisms of formation and uses are also described.http://www.sajs.co.za S Afr J Sci 2011; 107(3/4)

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This work reports the synthesis of β-cyclodextrin (β-CD)/cellulose (CA) nanofibers embedded with silver (Ag) and silver/iron (Ag/Fe) nanoparticles (NPs) via a benign process involving in situ electrospinning of the biopolymers with Ag and Fe salts. The electrospun nanocomposite fibers containing Ag+/Fe3+ ions were then subjected to UV photochemical reduction in the presence of water vapor under inert atmosphere to reduce the ions to zerovalent state. SEM and TEM revealed that the average diameter of the β-CD/CA nanofibers was 382.12 ± 30.09 nm and that the diameters of Ag and Ag/Fe NPs were 38.81 ± 8.21 nm and 56.29 ± 12.64 nm, respectively, after reduction. The XRD and EDS analysis confirmed the presence of the Ag and Fe NPs on the surface of the nanofibers. The effect of UV irradiation time on the reduction of the Ag+ and Fe3+ was studied by measuring the UV–vis absorbance of the reduced NPs. The biocidal effect of Ag and Ag/Fe was investigated using 12 different strains of bacteria. The Ag and Ag/Fe NPs embedded on the β-CD/CA nanofibers exhibited a strong biocidal effect on all of the bacteria strains.

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