Nafion/silicon oxide/phosphotungstic acid nanocomposite membrane with enhanced proton conductivity.

Nafion-silicon oxide (SiO2)-phosphotungstic acid (PWA) composite membrane has been synthesized to improve Nafion based proton exchange membrane fuel cell (PEMFC) performance. The objective of the study is to fabricate Nafion-SiO2-PWA nanocomposite membrane using sol–gel reaction. The composite is composed of the mixture of Nafion solution, tetra ethoxy orthosilane (TEOS) and PWA solution. The mixed solution was casted at certain temperature until transparent membrane is obtained. Peaks of SiO2 and PWA in the infrared spectra revealed that both inorganic and organic components are present in the modified Nafion based nanocomposite membrane. Analysis with fuel cell test station showed that higher current density was produced by nanocomposite membrane (82mAcm−2 at 0.6V for NS15W) than with the Nafion membrane (30mAcm−2 at 0.2 V) at 90 ◦C and 40% relative humidity. The internal resistance was seen to increase with the inorganic content. The internal resistances of the commercial Nafion (N112), NS10W, NS15W and NS20W are 6.33, 4.84, 1.33 and 3.6�cm2, respectively and their Tafel constants are 93.4, 84.4, 11.25 and 26.6 mV, respectively. While the nanocomposite membrane results were shown to be better than the commercial Nafion, the overall performances are comparable to those in the open literature

Surface water clarification using M. oleifera seeds.

Turbid surface water was treated using a pilot scale water treatment plant comprising coagulation, flocculation, sedimentation and rapid gravity filtration, using Moringa oleifera seeds/alum as coagulants. Turbidity removal of M. oleifera, alum, and the mixture of both M. oleifera/alum were compared, and results obtained were 7.2, 4.2 and 3.2 NTU, respectively. The turbidity achieved using M. oleifera/alum mixture and alum were less than the required standard of 5 NTU, while M. oleifera/alum mixture recorded the least turbidity value (3.2 NTU) with removal efficiency of 99%. The natural alkalinity of the water did not vary during the treatment processes. Therefore M. oleifera/alum mixture could be considered as a suitable alternative for partial replacement of alum as coagulant in surface water treatment, which is an added advantage since M. oleifera is a natural product with less or no side effects as compared to alum as a chemical agent

Continuous production of carbon nanotubes and diamond films by swirled floating catalyst chemical vapour deposition method

Various techniques for the synthesis of carbon nanotubes (CNTs) are being developed to meet an increasing demand as a result of their versatile applications. Swirled floating catalyst chemical vapour deposition (SFCCVD) is one of these techniques. This method was used to synthesise CNTs on a continuous basis using acetylene gas as a carbon source, ferrocene dissolved in xylene as a catalyst precursor, and both hydrogen and argon as carrier gases. Transmission electron microscopy analyses revealed that a mixture of single and multi-wall carbon nanotubes and other carbon nanomaterials were produced within the pyrolytic temperature range of 900–1 100°C and acetylene flow rate range of 118–370 ml min–1. Image comparison of raw and purified products showed that low contents of iron particles and amorphous carbon were contained in the synthesised carbon nanotubes. Diamond films were produced at high ferrocene concentration, hydrogen flow rate and pyrolysis temperatures, while carbon nanoballs were formed and attached to the surface of theCNTs at low ferrocene content and low pyrolysis temperature

Continuous production of carbon nanotubes and diamond films by swirled floating catalyst chemical vapour deposition method

Various techniques for the synthesis of carbon nanotubes (CNTs) are being developed to meet an increasing demand as a result of their versatile applications. Swirled floating catalyst chemical vapour deposition (SFCCVD) is one of these techniques. This method was used to synthesise CNTs on a continuous basis using acetylene gas as a carbon source, ferrocene dissolved in xylene as a catalyst precursor, and both hydrogen and argon as carrier gases. Transmission electron microscopy analyses revealed that a mixture of single and multi-wall carbon nanotubes and other carbon nanomaterials were produced within the pyrolytic temperature range of 900 - 1 100°C and acetylene flow rate range of 118 - 370 ml min - 1. Image comparison of raw and purified products showed that low contents of iron particles and amorphous carbon were contained in the synthesised carbon nanotubes. Diamond films were produced at high ferrocene concentration, hydrogen flow rate and pyrolysis temperatures, while carbon nanoballs were formed and attached to the surface of theCNTs at low ferrocene content and low pyrolysis temperature

The response effect of pheochromocytoma (PC12) cell lines to oxidized multi-walled carbon nanotubes (o-MWCMTs)

Background: The applications of oxidized carbon nanotubes (o-CNTs) have shown potentials in novel drug delivery including the brain which is usually a challenge. This underscores the importance to study its potential toxic effect in animals. Despite being a promising tool for biomedical applications little is known about the safety of drugs in treating brain diseases. The toxicity of oxidized multi-walled carbon nanotubes (o-MWCNTs) are of utmost concern and in most in-vitro studies conducted so far are on dendritic cell (DC) lines with limited data on PC12 cell lines. Objectives: We focused on the effect of o-MWCNTs in PC12 cells in vitro: a common model cell for neurotoxicity. Methods: The pristine multi-walled carbon nanotubes (p-MWCNTs) were produced by the swirled floating catalytic chemical vapour deposition method (SFCCVD). The p-MWCNTs were then oxidized using purified H2SO4/HNO3 (3:1v/v) and 30% HNO3 acids to produce o-MWCNTs. The Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM),Scanning electron microscopy (SEM), thermogravimetric analyser (TGA) and Raman spectroscopy techniques were used to characterize the MWCNTs. The PC12 cells were cultured in RPMI medium containing concentrations of o-MWCNTs ranging from 50 to 200 μg/ml. Results: The o-MWCNTs demonstrated slight cytotoxicity at short time period to PC12 neuronal cells whilst at longer time period, no significant (p > 0.05) toxicity was observed due to cell recovery. Conclusion: In conclusion, the o-MWCNTs did not affect the growth rate and viability of the PC12 cells due to lack of considerable toxicity in the cells during the observed time period but further investigations are required to determine cell recovery mechanism