Photocatalytic activity of titanium dioxide nanotubes following long-term aging

Anodic titanium dioxide (TiO2) nanotubes were found to be active photocatalysts. These photocatalysts possess a high surface area, even when supported, rendering them potential candidates for water treatment. In this work, photocatalytic surfaces were produced by anodizing commercially pure Ti plates using two different electrolyte compositions and correspondingly diverse process parameters. Changes in the physical and chemical stability as well as photocatalytic activity were studied over a fifty-two-week aging process. During this period, the nanotubular surfaces were exposed to flowing synthetic greywater, solar irradiation, and the natural environment. The physical and phase stability of the materials anodized using the organic electrolyte were found to be outstanding and no degradation or change in crystalline structure was observed. On the other hand, materials anodized in the aqueous electrolyte proved to suffer from light-induced phase transition from anatase to rutile. Surfaces synthesized in the organic electrolyte were more resistant to fouling and showed a better tendency to recover photocatalytic activity upon cleaning. In conclusion, the nanotubes produced in the organic electrolyte proved to be stable, rendering them potentially suitable for real-life applications.peer-reviewe

Synthesis of ZnO/PMMA nanocomposite by low-temperature atomic layer deposition for possible photocatalysis applications

Zinc oxide is one of the most widely used semiconductors, thanks to its shallow band-gap of 3.3 eV, low cost, inertness, and abundance in nature. On the other hand, poly (methyl methacrylate) (PMMA) is a common thermoplastic material used in many applications namely because of its transparency, environmental stability, and low cost. The realization of novel inorganic/polymeric hybrid nanomaterials is appealing, being beneficial in a variety of applications including photocatalysis, sensing, energy harvesting and storage, and optoelectronics, but also challenging. In this work, ZnO and PMMA were combined using the atomic layer deposition (ALD) technique. The morphology of the samples was evaluated by scanning electron microscopy (SEM), while the crystallinity has been investigated using X-ray diffraction (XRD) analyses. In order to give a proof of concept of a possible application of the materials synthetized, the photocatalytic activity of the nanocomposites has been tested by the degradation of two organic pollutants in water: methylene blue (MB) dye and sodium lauryl sulfate (SDS), an anionic surfactant. The results have shown that all samples are active in the removal of both pollutants (i.e., MB and SDS), opening the route for the application of the proposed nanocomposites in water treatment.peer-reviewe

Effect of the surface morphology of TiO2 nanotubes on photocatalytic efficacy using electron-transfer-based assays and antimicrobial tests

The application of titanium oxide nanotubes for the removal of contaminants from freshwater is a rapidly growing scientific interest, especially when it comes to water conservation strategies. In this study we employed four different titanium oxide nanotube surfaces, prepared by a two-electrode anodic oxidation. Two of the surfaces were synthesised in aqueous media, while the other two surfaces were synthesised in ethylene glycol. One of the arrays synthesised in the organic medium was impregnated with silver nanoparticles, while the remaining surfaces were not. The chemical reactivity of the various surfaces was assessed using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,20 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as free electron sensitive probe molecules, in parallel with tannic acid degradation and copper ion reducing capacity. The potential antimicrobial activity of the surfaces was assessed against a panel of microorganisms composed of yeast, fungi, Gram-positive and Gram-negative bacteria. Field emission scanning electron microscopy revealed that surfaces produced in the aqueous medium had a smaller tube length and a smaller tube diameter. It was noted that one of the materials using sodium sulfate as the supporting electrolyte had the most irregular nanostructure morphology with tubes growing to the side rather than vertically. The structural variation of the surfaces directly reflected both the chemical and biological activity, with the nanotubes formed in ethylene glycol showing the fastest rates in the stabilization of DPPH and ABTS radicals, the fastest tannic acid decomposition under various pH conditions and the fastest metal reducing activity. Furthermore, the surface containing silver and its bare counterpart showed the most effectivepeer-reviewe

Suitability of different titanium dioxide nanotube morphologies for photocatalytic water treatment

Photocatalysis has long been touted as one of the most promising technologies for environmental remediation. The ability of photocatalysts to degrade a host of different pollutants, especially recalcitrant molecules, is certainly appealing. Titanium dioxide (TiO2) has been used extensively for this purpose. Anodic oxidation allows for the synthesis of a highly ordered nanotubular structure with a high degree of tunability. In this study, a series of TiO2 arrays were synthesised using different electrolytes and different potentials. Mixed anatase-rutile photocatalysts with excellent wettability were achieved with all the experimental iterations. Under UVA light, all the materials showed significant photoactivity towards different organic pollutants. The nanotubes synthesised in the ethylene glycol-based electrolyte exhibited the best performance, with near complete degradation of all the pollutants. The antibacterial activity of this same material was similarly high, with extremely low bacterial survival rates. Increasing the voltage resulted in wider and longer nanotubes, characteristics which increase the level of photocatalytic activity. The ease of synthesis coupled with the excellent activity makes this a viable material that can be used in flat-plate reactors and that is suitable for photocatalytic water treatment.peer-reviewe

Ag/ZnO/PMMA nanocomposites for efficient water reuse

This work attempts to produce photocatalytic surfaces for large-scale applications by depositing nanostructured coatings on polymeric substrates. ZnO/poly(methyl methacrylate) (PMMA) composites were prepared by low-temperature atomic layer deposition (ALD) of ZnO on PMMA substrates. In addition, to increase the photocatalytic and antibacterial activities of ZnO films, Ag nanoparticles were added on ZnO surfaces using plasma-enhanced ALD. The morphology, crystallinity, and chemical composition of the specimens were meticulously examined by scanning and transmission electron microscopies, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. The noteworthy photocatalytic activity of the nanocomposites was proved by the degradation of the following organic pollutants in aqueous solution: methylene blue, paracetamol, and sodium lauryl sulfate. The antibacterial properties of the samples were tested using Escherichia coli as a model organism. Moreover, the possible toxic effects of the specimens were checked by biological tests. The present results unambiguously indicate the Ag/ZnO/PMMA nanocomposite as a powerful tool for an advanced wastewater treatment technology.peer-reviewe

Sunetti ta’ William Shakespeare

Ġabra ta’ poeżiji u proża li tinkludi: Grand Prix ta’ Carmel Azzopardi – Pizza marinara ta’ Carmel Azzopardi – Ħajku ta’ Kit Azzopardi – Ix-xemgħa qiegħda ta’ Charles Bezzina – U taħti ramel, ramel ta’ Charles Bezzina – Vażett ta’ Ġorġ Borg – Bniedem li mhux ta’ Ġorġ Borg – Il-ħajbu ta’ Antoine Cassar – Il-mistoħbija ta’ Manwel Cassar – Għasel ta’ Carmel G. Cauchi – Dgħajsa ta’ Carmel G. Cauchi – Ħitan ta’ Alfred Degabriele – Skeletru silwett...f’realtà moħbija ta’ Stefano Farrugia – Minjatura tal-enimmi ta’ Stefano Farrugia – Mnejn jgħaddi Kristu ta’ Joe Friggieri – Rebbiegħa ta’ Reno Fenech – Blogger ta’ Charles Flores – Veġeterjana ta’ Charles Flores – Mejju ta’ Joe P. Galea – Kien hemm lejla u tmien nisa ta’ Claudia Gauci – Ħobbni ta’ Sergio Grech – Mitlufin ta’ Maria Grech Ganado – Moħħi ta’ Maria Grech Ganado – Viżjoni ta’ Maria Grech Ganado – Inkontinenza ta’ Adrian Grima – Andrew jħebb in-nar ta’ Adrian Grima – It-Tlieta, 20 ta’ Lulju 2004 ta’ Alfred Massa – Fuq l-għolja tal- Verdala ta’ Jane Micallef – Imm’issa ta’ Jane Micallef – Baby blues ta’ Immanuel Mifsud – Ġo dar sawra ta’ Immanuel Mifsud – Lil Dun Karm ta’ Maurice Mifsud Bonnici – Il-fuklar ta’ Achille Mizzi – Ut videam ta’ Achille Mizzi – Karnival solitarju ta’ Patrick Sammut – Mill-baħħ etern ta’ Joe Zammit Tabona – ...fil-ħmieġ ta’ ftit blatiet... ta’ Paul P. Borg – Bħall-qasab ta’ Steve Borg – L-aħħar żjara ta’ Victor Fenech – Ħelwa.morra 18 ta’ Ann Marie Schembri – Jack & Jill ta’ Trevor Żahra – Għadbilura ta’ Russell Davis, traduzzjoni ta’ Toni Aquilina – Sunetti ta’ William Shakespeare, traduzzjoni ta’ Oliver Friggieri.peer-reviewe

Nikteb...

Ġabra ta’ poeżiji u proża li tinkludi: L-iben il-ħali ta’ David Agius Muscat – Kaptan ta’ Kit Azzopardi – Il-lanterna ta’ Charles Bezzina – Li kelli mmur lura ta’ Ġorġ Borg – Firda ta’ Ġorġ Borg – Garden fairy ta’ Charles Briffa – Sejf jinfidlek ruħek ta’ Charles Briffa – Waqt ta’ Joseph Buttigieg – Vjaġġ ta’ John Caruana – Ċaqlembuta ta’ Antoine Cassar – Ħaġa tqila ta’ Carmel G. Cauchi – F’tarf il-blat ta’ Leanne Ellul – Int ta’ Victor Fenech – Pippin u l-bojja ta’ Charles Flores – L-arloġġ ta’ Joe Friggieri – Il-fjur tal-ġakaranda ta’ Joe Friggieri – Fjur tal-kaktus ta’ Joel Galea – Biss is-skiet ta’ Joel Galea – Għalissa ta’ Maria Grech Ganado – Ilsna ta’ Maria Grech Ganado – Is-sried ixoqqna fin fin ta’ Adrian Grima – Ħsieb ħalliel... ta’ Patrick Sammut – Lament lil ommi ta’ Salv Sammut – Hekk kif tinħass ġol-arja x-xitwa ta’ Lillian Sciberras – F’għajnejha, il-ħarsa siekta ta’ Clare Azzopardi – Għad jagħdab l-irdum ta’ Paul P. Borg – Forsi...xi darba ta’ Charles Casha – Faxxa ngħas ta’ Sergio Grech – Il-mejda tal-mogħdija ta’ Pierre J. Mejlak – Min jaf bi Stojan Kurepa? ta’ Immanuel Mifsud – L-eħrex jum tal-gwerra ta’ Maurice Mifsud Bonnici – Il-vażett tal-bewsiet ta’ Rita Saliba – Pjanu ta’ Trevor Żahra – Il-ħalliel ta’ Guy de Maupassant, traduzzjoni ta’ Toni Aquilina – Salvu tal-pasturi ta’ Francis Ebejer, traduzzjoni ta’ Steve Borg – Sunetti ta’ William Shakespeare, traduzzjoni ta’ Oliver Friggieri – Nikteb... ta’ Nizar Qabbani, traduzzjoni ta’ Kevin Saliba.peer-reviewe

Mediterran

Ġabra ta’ poeżiji u proża li tinkludi: Għal Ġorġ Pisani ta’ Joe Zammit Tabona – Din gżira niexfa ta’ Clare Azzopardi – Ersaqt lejn il-baħar ta’ Charles Bezzina – Passaġġi ta’ Ġorġ Borg – Firenze ta’ Louis Briffa – Riħet ix-xemgħa ta’ John Caruana – Jum ir-riflessjoni ta’ Antoine Cassar – Fjura fqajra ta’ Carmel Ġ. Cauchi – Qatra ta’ Maria Grech Ganado – Lill-bufula ta’ fuq iz-zuntier ta’ Maurice Mifsud Bonnici – Tinsinix! ta’ Joe Zammit Tabona – In-nanna lbieraħ u jien illum! – tifkiriet ta’ Lina Brockdorff – L-għaddas ta’ Alex Vella Gera – Għassa ta’ Adrian Grima – It-tfajla tal-ħolm ta’ Anne Marie Scerri – Meta tagħmel l-ewwel xita ta’ Trevor Żahra – Ħajta deni ta’ Jordi Punti, traduzzjoni ta’ Immanuel Mifsud – Arnarstapi, l-Iżlanda ta’ Susan Richardson, traduzzjoni ta’ Simone Inguanez – Ħuta ta’ Aki Salmela, traduzzjoni ta’ Simone Inguanez – Ma kellniex triq oħra ta’ Roman Simic, traduzzjoni ta’ Immanuel Mifsud – Mediterran ta’ Cruciani Valerio, traduzzjoni ta’ Antoine Cassar.peer-reviewe

Fil-lejl li kiber miegħi

Ġabra ta’ poeżiji u proża li tinkludi: Flus lura ta’ Charles Clews – Afrika ta’ Oliver Friggieri – 5 ta’ Ottubru 1798: Ir-rewwixta taż-Żabbarin kontra l-Franċiżi ta’ Achille Mizzi – Durham ta’ Joe Friggieri – Tifkiriet: Għand Majsi l-parrukkier ta’ Maurice Mifsud Bonnici – Jacqueline ta’ Carmel Azzopardi – Is-Sibt 29 ta’ Marzu 1986 ta’ Alfred Massa – Lill-għasfur ta’ Nikol Vella Apap – Nixtieq nibki ta’ John Caruana – Imbierka s-sapjenza ta’ Charles Clews – Par għajnejn fid-dlam ta’ Val. V. Barbara – Iż-żmien u l-bniedem ta’ Paul J. Debono – Dixx ta’ l-istejnles stil ta’ Paul P. Borg – Nota bene ta’ Sergio Grech – Ħitan ta’ Alfred Degabriele – Data base ta’ Philip Sciberras – Freddie Mercury – Ġieħ ta’ Charles Briffa – Ħolma ta’ Joe Bugeja – L-imsiebaħ firxu d-dwal ta’ Emanuel F. Attard – Żamma ta’ Manwel Cassar – Awtur tal-baħar ta’ Charles Bezzina – Nixxiegħa tal-kuxjent minn Triq Ħas-Sajjied Birkirkara ta’ Tarcisio Zarb – Ċfuf u żigarelli ta’ Ġorġ Borg – Taħt is-saffi tqal ta’ Ġorġ Borg – Fil-lejl li kiber miegħi ta’ Ġorġ Borg.peer-reviewe

Afrika

Ġabra ta’ poeżiji u proża li tinkludi: Kavallier ta’ Sergio Grech – Tiġrib ta’ Toni Aquilina – Kappella pprofanata ta’ Ġorġ Borg – Leħħiet ta’ Pawlu Aquilina – Fir-raqda ħadra ta’ Carmel Calleja – Epigrammi: X’dinja din! ta’ J. J. Camilleri – Karnival 1999 (Għawdex) ta’ Joe M. Attard – Ħarsti lejn l-art ta’ Ġorġ Zammit – Lill-mewt ta’ J. Zammit Tabona – Tifkira ta’ Lillian Sciberras – Lill-pitirross ta’ K. Vella Haber – Lill-irġiel miżżewġa ta’ Ġanni A. Cilia – Meta Hamlet u l-fjuri eterni jiltaqgħu ta’ Doreen Micallef – It-tren iżomm il-ħin ta’ Pawlu Aquilina – Kemm tiswa tarbija? ta’ Ġorġ Mallia – Jien naf ta’ J. J. Cremona – Odessa ta’ Charles Coleiro – L-isptar ta’ Charles Coleiro – Agunija ta’ Charles Coleiro – Milied XXI ta’ Charles Coleiro – Entużjażmu ta’ Charles Briffa – Londra ta’ Charles Briffa – Dal-ġebel kbir ta’ Emanuel Attard – Lit-Teatru Rjal ta’ Maurice Mifsud Bonnici – Fl-Ewropa magħquda ta’ Doreen Micallef – Fil-mewt ta’ Ġorġ Pisani ta’ Carm Cachia – Lejl id-19 ta’ Diċembru ta’ Charles B. Spiteri – Kont waħdi ta’ Suzanne Gatt – Imħabbti ta’ Nathalie Micallef – Xi ġralek, Ma? ta’ Oliver Friggieri – Anki t-tislima ta’ Oliver Friggieri – Fuq xifer nimxu ta’ Oliver Friggieri – Afrika ta’ Oliver Friggieri.peer-reviewe