A novel fabrication approach for multifunctional graphene-based thin film nano-composite membranes with enhanced desalination and antibacterial characteristics

A practical fabrication technique is presented to tackle the trade-off between the water flux and salt rejection of thin film composite (TFC) reverse osmosis (RO) membranes through controlled creation of a thinner active selective polyamide (PA) layer. The new thin film nano-composite (TFNC) RO membranes were synthesized with multifunctional poly tannic acid-functionalized graphene oxide nanosheets (pTA-f-GO) embedded in its PA thin active layer, which is produced through interfacial polymerization. The incorporation of pTA-f-GOL into the fabricated TFNC membranes resulted in a thinner PA layer with lower roughness and higher hydrophilicity compared to pristine membrane. These properties enhanced both the membrane water flux (improved by 40%) and salt rejection (increased by 8%) of the TFNC membrane. Furthermore, the incorporation of biocidal pTA-f-GO nanosheets into the PA active layer contributed to improving the antibacterial properties by 80%, compared to pristine membrane. The fabrication of the pTA-f-GO nanosheets embedded in the PA layer presented in this study is a very practical, scalable and generic process that can potentially be applied in different types of separation membranes resulting in less energy consumption, increased cost-efficiency and improved performance.Hanaa M. Hegab, Ahmed ElMekawy, Thomas G. Barclay, Andrew Michelmore, Linda Zou, Dusan Losic, Christopher P. Saint and Milena Ginic-Markovi

Towards effective small scale microbial fuel cells for energy generation from urine

© 2016 The Authors. Published by Elsevier Ltd. To resolve an increasing global demand in energy, a source of sustainable and environmentally friendly energy is needed. Microbial fuel cells (MFC) hold great potential as a sustainable and green bioenergy conversion technology that uses waste as the feedstock. This work pursues the development of an effective small-scale MFC for energy generation from urine. An innovative air-cathode miniature MFC was developed, and the effect of electrode length was investigated. Two different biomass derived catalysts were also studied. Doubling the electrode length resulted in the power density increasing by one order of magnitude (from 0.053 to 0.580 W m-3). When three devices were electrically connected in parallel, the power output was over 10 times higher compared to individual units. The use of biomass-derived oxygen reduction reaction catalysts at the cathode increased the power density generated by the MFC up to 1.95 W m-3, thus demonstrating the value of sustainable catalysts for cathodic reactions in MFCs

Improved power and long term performance of microbial fuel cell with Fe-N-C catalyst in air-breathing cathode

© 2017 Power output limitation is one of the main challenges that needs to be addressed for full-scale applications of the Microbial Fuel Cell (MFC) technology. Previous studies have examined electrochemical performance of different cathode electrodes including the development of novel iron based electrocatalysts, however the long-term investigation into continuously operating systems is rare. This work aims to study the application of platinum group metals-free (PGM-free) catalysts integrated into an air-breathing cathode of the microbial fuel cell operating on activated sewage sludge and supplemented with acetate as the carbon energy source. The maximum power density up to 1.3 Wm−2 (54 Wm−3) obtained with iron aminoantipyrine (Fe-AAPyr) catalyst is the highest reported in this type of MFC and shows stability and improvement in long term operation when continuously operated on wastewater. It also investigates the ability of this catalyst to facilitate water extraction from the anode and electroosmotic production of clean catholyte. The electrochemical kinetic extraction of catholyte in the cathode chamber shows correlation with power performance and produces a newly synthesised solution with a high pH > 13, suggesting caustic content. This shows an active electrolytic treatment of wastewater by active ionic and pH splitting in an electricity producing MFC

Interlayer growth of borates for highly adhesive graphene coatings with enhanced abrasion resistance, fire-retardant and antibacterial ability

Available online 23 February 2017Surface coatings to protect materials from mechanical abrasion, fire and microbial colonization are associated with billion dollars of expenses across broad range of industrial, domestic and defence applications. Currently used protective coatings based on heavy metals, halogenated fire-retardation, and biocide agents have considerable environmental concerns due their toxicity, and lack of effectiveness with limited functionality. In this paper, we present engineering of new multifunctional coating based on graphene composites with the ability to provide “3-in-1” protective properties. These multiple functionalities were created with specially designed graphene composite by growing sodium metaborate (NaBO2·xH2O) crystals into graphene oxide (GO) layer during their reduction, which works synergistically as a surface binder, a flame-retardant additive, and an antibacterial agent. The testing of protective coating performances revealed an outstanding mechanical robustness (ASTM-class 4B), and the reduction of bacterial colonization up to ∼99.92%. The high flame retardant performance of the coated wood, and paper showed non-flammability, strong intumescent effect, and self-extinguishing ability during fire. These protective coatings based on graphene composites due the simplicity of their formulations, scalability, and outstanding performance offer a great potential for their industrial, structural, and environmental applications.Md J. Nine, Diana N.H. Tran, Ahmed ElMekawy, Dusan Losi

Efficient synthesis of supported proline catalysts for asymmetric aldol reactions

Proline has been grafted onto silica supports in a single step by reacting trans-4-hydroxy-L-proline with chloropropyl tethers, without the use of protecting groups for the proline amine and carboxylic acid functional groups. The resulting catalysts have been characterised to show that grafting is through reaction with the 4-hydroxy group. The catalysts have been tested in an asymmetric aldol reaction, and shown to be both more active and more enantioselective than equivalent catalysts prepared using a protection/deprotection route for the proline grafting ste

Cathodes for Microbial Fuel Cells

<p>Increase in human activities across the globe has put forward several challenges for future generations, with uncontrolled energy demand near the top of the list. Relentless efforts are being made by researchers and policy makers to meet energy demands in renewable ways, which shows the possibility of several alternative energy systems. Microbial fuel cell (MFC) is one such alternative energy generating system with an additional advantage of valorization of waste. Research in the field of MFC started almost a decade ago and significant improvement was reported up to pilot-scale operations, in spite of its inherent limitations. Cathodic reduction reaction is also as crucial as anodic oxidation in MFC. Plenty of reports consolidated the research outlined in the direction of anodic oxidation, while very few reports have been reported on cathodic reduction in comparison. In this chapter, we brought together all the efforts made by researchers toward cathodic reduction to create a comprehensive understanding of the system.</p