Publications by authors named "Claudia L Bianchi"

31 Publications

Doped-polyaniline based sorbents for the simultaneous removal of heavy metals and dyes from water: Unravelling the role of synthesis method and doping agent.

Chemosphere 2021 Aug 19;286(Pt 3):131941. Epub 2021 Aug 19.

Department of Chemistry, University of Milan, Via C. Golgi 19, 20133, Milan, Italy; INSTM, Via Giusti 9, 50121, Florence, Italy; ISTM-CNR, Via Golgi 19, 20133, Milano, Italy. Electronic address:

Recently, the engineering of alternative adsorbents with better functional and sorbing ability towards the purification of wastewaters has received much attention from the scientific community. Currently polymers, in particular, are regarded as attractive soft materials in the field of environmental remediation due to their several unique properties. In this regard, the synthesis method is key point to fabricate polymer-based adsorbent with targeted characteristics. In the present work, four polyaniline (PANIs) samples were synthesized by two alternative chemical approaches, a traditional one and an eco-friendly one, and two different dopants were used, HCl and HSO respectively. All PANIs were characterized for their thermal, optical, morphological, and structural properties and their capability to remove simultaneously dyes and heavy metals from water have been investigated. It was deduced that the sorption ability is dependent on the as-synthesized PANI using different procedures and dopants. All the PANIs from traditional method showed high levels of pollutants removal (from 89 to 97%). Even though the materials obtained from the green way are overall less active, HSO-doped corresponding polymer showed high sorption capability (75-97%). Finally, the most performing PANIs were selected for recycling tests exhibiting high sorption efficiency retention up to four runs without any regeneration treatment. Most important, the cycling tests were stopped well before the sample sorption limit could be reached.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2021.131941DOI Listing
August 2021

A review of advances in multifunctional XTiO perovskite-type oxides as piezo-photocatalysts for environmental remediation and energy production.

J Hazard Mater 2021 Jul 31;421:126792. Epub 2021 Jul 31.

Department of Chemistry, Università degli Studi di Milano, INSTM Unit Milano-Università, and CNR-SCITEC, via Golgi 19, 20133 Milano, Italy.

Over more than three decades, the field of engineering of photocatalytic materials with unique properties and enhanced performance has received a huge attention. In this regard, different classes of materials were fabricated and used for different photocatalytic applications. Among these materials, recently multifunctional XTiO perovskites have drawn outstanding interest towards environmental remediation and energy conversion thanks to their unique structural, optical, physiochemical, electrical and thermal characteristics. XTiO perovskites are able to initiate different surface catalytic reactions. Under ultrasonic vibration or heating, XTiO perovskites can induce piezo-catalytic reactions due to the titling of their conduction and valence bands, resulting in the formation of separated charge carriers in the medium. In addition, under light irradiation, XTiO perovskites are considered as a new class of photocatalysts for environmental and energy related applications. Herein, we addressed the recent advances on variously synthesized, doped and formulated XTiO perovskite-type oxides showing piezo- and/or photocatalytic exploitation in environmental remediation and energy conversion. The control of structural crystallite size and phase, conductivity, morphology, oxygen vacancy control, doping agents and ratio has a significant role on the photocatalytic and piezocatalytic activities. The different piezo or/and photocatalytic processes mechanistic pathways towards varying applications were discussed. The current challenges facing these materials and future trends were addressed at the end of the review.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2021.126792DOI Listing
July 2021

Self-cleaning, photocatalytic films on aluminum plates for multi-pollutant air remediation: promoting adhesion and activity by SiOinterlayers.

Nanotechnology 2021 Sep 1;32(47). Epub 2021 Sep 1.

Ghent University, Department of Solid State Sciences, Ghent, Belgium.

In recent years, nanoparticles have come under close scrutiny for their possible health and environmental issues, making them less attractive for photocatalytic applications in air or water purification. Replacing free nano-powders with active and stable films is thus a fundamental step towards developing effective photocatalytic devices. Aluminum represents a cheap and technologically-relevant substrate, but its photocatalytic applications have been hampered by adhesion issues and metal ion diffusion within the photocatalytic layer. In this work, the use of silica interlayers is investigated as a strategy to promote adhesion, efficiency and reusability of TiOfilms deposited on aluminum plates. Films were prepared from stable titania sols to avoid the use of nano-powders. Aluminum substrates with different surface morphology were investigated and the role of the silica interlayer thickness was studied. Films were extensively characterized, studying their structure, morphology, optical properties, adhesion and hardness. Self-cleaning properties were studied with respect to their superhydrophilicity and ability to resist fouling via alkylsilanes. Photocatalytic degradation tests were carried out using both volatile organic compounds and NO, also in recycle tests. The presence of the silica interlayer proved crucial to promote the film robustness and photocatalytic activity. The substrate morphology determined the optimal interlayer thickness, especially in terms of the film reusability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6528/ac1d76DOI Listing
September 2021

Piezo-enhanced photocatalytic diclofenac mineralization over ZnO.

Ultrason Sonochem 2021 Jul 1;75:105615. Epub 2021 Jun 1.

Department of Chemistry, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), via Giusti 9, 50121 Florence, Italy; ISTM-CNR, via Golgi 19, 20133 Milano, Italy. Electronic address:

The degradation of diclofenac has been realized for the first time by a piezo-enhanced sonophotocatalytic approach based on ZnO. The sonophotocatalytic degradation showed a slight enhancement in the degradation of the parent compound, whereas strong synergistic effects were observed for the mineralization process when suitable ZnO morphologies are used, reaching 70% of complete degradation of 25 ppm diclofenac using 0.1 g/L ZnO in 360 min. Tests in a complex water matrix show enhanced diclofenac removal, outperforming a TiO benchmark photocatalyst. These promising experimental results promote this process as a good alternative to traditional degradation approaches for remediation of real water matrices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2021.105615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8193124PMC
July 2021

Comparison of the photoactivity of several semiconductor oxides in floating aerogel and suspension systems towards the reduction of Cr(VI) under visible light.

Chemosphere 2021 Oct 10;281:130839. Epub 2021 May 10.

Università Degli Studi di Milano, Dip. Chimica and INSTM-UdR Milano, Via Golgi, 19, 20133, Milano, Italy.

A massive amount of research has been done over the last three decades to develop photoactive materials which could be suitable for real-world use in water remediation sector. Water-floating photocatalysts could be one of the best options due to their technological characteristics in terms of efficiency and reasonability including a high oxygenation of the photocatalyst surface, a fully sunlight irradiation, easy recovery and reuse. In the present study, aerogel water-floating based materials were fabricated using poly(vinyl alcohol) and polyvinylidene fluoride as a polymer platform, and loaded with different semiconductors such as g-CN, MoO, BiO, FeO or WO. The photocatalytic efficiencies of aerogel floating materials and the suspension of above-mentioned semiconductors were compared evaluating the photoreduction of Cr(VI) under visible light (λ > 420 nm). The results showed that FeO suspension was the most efficient but the slowest in floating system. On the contrary, g-CN exhibited a good performance in suspension system, and on top of that it was very effective in floating system, wherein it ensures a total reduction of 10 ppm-Cr(VI) to Cr(III) within 20 min.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2021.130839DOI Listing
October 2021

Electron paramagnetic resonance of sonicated powder suspensions in organic solvents.

Ultrason Sonochem 2021 May 26;73:105544. Epub 2021 Mar 26.

Polytechnique Montréal - Department of Chemical Engineering, C.P. 6079, Centre Ville, H3C 3A7 Montréal, QC, Canada. Electronic address:

The chemical effects of the acoustic cavitation generated by ultrasound translates into the production of highly reactive radicals. Acoustic cavitation is widely explored in aqueous solutions but it remains poorly studied in organic liquids and in particular in liquid/solid media. However, several heterogeneous catalysis reactions take place in organic solvents. Thus, we sonicated trimethylene glycol and propylene glycol in the presence of silica particles (SiO) of different sizes (5-15 nm, 0.2-0.3 µm, 12-26 µm) and amounts (0.5 wt% and 3 wt%) at an ultrasound frequency of 20 kHz to quantify the radicals generated. The spin trap 5,5-dimethyl-1-pyrrolin-N-oxide (DMPO) was used to trap the generated radicals for study by electron paramagnetic resonance (EPR) spectroscopy. We identified the trapped radical as the hydroxyalkyl radical adduct of DMPO, and we quantified it using stable radical 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a quantitation standard. The concentration of DMPO spin adducts in solutions containing silica size 12-26 µm was higher than the solution without particles. The presence of these particles increased the concentration of the acoustically generated radicals by a factor of 1.5 (29 µM for 0.5 wt% of SiO size 12-26 µm vs 19 µM for 0 wt%, after 60 min of sonication). Ultrasound produced fewest radicals in solutions with the smallest particles; the concentration of radical adducts was highest for SiO particle size 12-26 µm at 0.5 wt% loading, reaching 29 µM after 60 min sonication. Ultrasound power of 50.6 W produced more radicals than 24.7 W (23 µM and 18 µM, respectively, at 30 min sonication). Increased temperature during sonication generated more radical adducts in the medium (26 µM at 75 °C and 18 µM at 61 °C after 30 min sonication). Acoustic cavitation, in the presence of silica, increased the production of radical species in the studied organic medium.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2021.105544DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8047979PMC
May 2021

Sonophotocatalytic degradation of sodium diclofenac using low power ultrasound and micro sized TiO.

Ultrason Sonochem 2020 Oct 7;67:105123. Epub 2020 Apr 7.

Università degli Studi di Milano, Dipartimento di Chimica, via Golgi, 19 - 20133 Milano, Italy. Electronic address:

The nonsteroidal anti-inflammatory drug sodium diclofenac (DC) is an emerging water pollutant which resists conventional wastewater treatments. Here the sonophotocatalytic degradation of DC was carried out using micrometric TiO (both pristine and Ag-decorated), UV-A irradiation and 20 kHz pulsed ultrasound. Sonophotocatalytic tests were compared with photolysis, sonolysis, sonophotolysis, sonocatalysis and photocatalysis data performed in the same conditions. A synergy index of over 2 was determined for tests with pristine TiO, while values close to 1.3 were observed for Ag-TiO. Reaction intermediates were studied by HPLC-MS, showing degradation mechanisms activated by hydroxyl radicals. Similar pathways were identified for photocatalytic and sonophotocatalytic tests, although the latter led to more oxidized compounds. Different reactor configurations (static and dynamic set ups) were studied. Sequential and simultaneous application of UV light and ultrasound led to similar performance. The role of water matrix was investigated using ultrapure and drinking water, showing marked detrimental effects of electrolytes on the DC degradation. Overall, the combined treatment proved more efficient than photocatalysis alone especially in demanding working conditions, like in drinking water matrices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2020.105123DOI Listing
October 2020

Ultrasound-assisted synthesis of ZnO photocatalysts for gas phase pollutant remediation: Role of the synthetic parameters and of promotion with WO.

Ultrason Sonochem 2020 Sep 31;66:105119. Epub 2020 Mar 31.

Department of Chemistry, Università degli Studi di Milano, Italy; Consorzio INSTM, Florence, Italy.

The synthesis of ZnO photocatalysts by ultrasound-assisted technique was here investigated. Several experimental parameters including the zinc precursor (acetate, chloride, nitrate), sonication conditions (amplitude, pulse) and post-synthetic thermal treatment (up to 500 °C) were studied. Crystalline ZnO samples were obtained without thermal treatments due to the adopted reactant ratios and synthesis temperature. Sonication plays a major role on the morphological oxide features in terms of particle size and surface area, the latter showing a 20-fold increase with respect to conventional synthesis. Interestingly, 1 and 3 s sonication pulses led to morphological properties similar to continuous sonication. A thermal treatment at moderate temperatures (400-450 °C) promoted the loss of surface hydroxylation and the formation of lattice defects, while higher temperatures were detrimental for the sample morphology. The prepared ZnO was decorated with WO particles comparing an ultrasound-assisted technique using 1 s pulses with a conventional approach, giving rise to composites with promoted visible light absorption. Samples were tested towards the photocatalytic degradation of nitrogen oxides (500-1000 ppb) in humidified air under both UV and visible light. By carefully controlling the synthetic procedure, better performance were observed with respect to the commercial benchmark. Samples from ultrasound-assisted syntheses, also in the case of pulsed sonication, showed consistently better results than conventional references, in particular for ZnO-WO composites. The composite by ultrasound-assisted synthesis showed > 95% degradation in 180 min and doubled NO degradation under visible light with respect to the conventional composite.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2020.105119DOI Listing
September 2020

Experimental Characterization of Polymer Surfaces Subject to Corona Discharges in Controlled Atmospheres.

Polymers (Basel) 2019 Oct 10;11(10). Epub 2019 Oct 10.

Ricerca sul Sistema Energetico (RSE S.p.A.), 20134 Milano, Italy.

Polymeric dielectrics are employed extensively in the power transmission industry, thanks to their excellent properties; however, under normal operating conditions these materials tend to degrade and fail. In this study, samples of low-density polyethylene, polypropylene, polymethyl methacrylate, and polytetrafluorethylene were subjected to corona discharges under nitrogen and air atmospheres. The discharges introduced structural modifications over the polymer surface. From a chemical perspective, the alterations are analogous among the non-fluorinated polymers (i.e., polyethylene (PE), polypropylene (PP), and polymethyl methacrylate (PMMA)). A simulation of the corona discharge allowed the identification of highly reactive species in the proximity of the surface. The results are consistent with the degradation of insulating polymers in high-voltage applications due to internal partial discharges that ultimately lead to the breakdown of the material.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/polym11101646DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836313PMC
October 2019

Photocatalytic porcelain grés large slabs digitally coated with AgNPs-TiO.

Environ Sci Pollut Res Int 2019 Dec 25;26(36):36117-36123. Epub 2019 Apr 25.

IrisCeramica Group, Via Ghiarola Nuova 119, 41042, Fiorano M.se (MO), Italy.

TiO is employed as both photocatalytic and structural materials, leading to its applications in external coatings or in interior furnishing devices, including cement mortar, tiles, floorings, and glass supports. The authors have already demonstrated the efficiency of photoactive micro-sized TiO and here its industrial use is reported using the digital printing to coat porcelain grés slabs. Many advantages are immediately evident, namely rapid and precise deposition, no waste of raw materials, thus positively affecting the economy of the process. Data for the thin films deposited by digital printing were compared with those obtained for the conventional spray method. The use of metal-doped TiO is also reported so that the photoactivity of these materials can be exploited even under LED light. The digital inkjet printed coatings exhibited superior photocatalytic performance owing to both higher exposed surface area and greater volume of deposited anatase, as well as the greater areal distribution density of thinly and thickly coated regions. Moreover, the presence of TiO doped silver increased the efficiency of the materials in NOx degradation both under UVA and LED lights.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-019-05218-7DOI Listing
December 2019

Nano-MnO₂ Decoration of TiO₂ Microparticles to Promote Gaseous Ethanol Visible Photoremoval.

Nanomaterials (Basel) 2018 Sep 3;8(9). Epub 2018 Sep 3.

Chemistry Department, University of Milan, via Golgi 19, 20133 Milano, Italy.

TiO₂-based photocatalysis under visible light is an attractive way to abate air pollutants. Moreover, developing photocatalytic materials on a large-scale requires safe and low-cost precursors. Both high-performance TiO₂ nanopowders and visible-light active noble metals do not match these requirements. Here, we report the design of novel Mn-decorated micrometric TiO₂ particles. Pigmentary TiO₂ replaced unsafe nano-TiO₂ and firmly supported MnO particles. Mn replaced noble metals such as Au or Ag, opening the way for the development of lower cost catalysts. Varying Mn loading or pH during the impregnation affected the final activity, thus giving important information to optimize the synthesis. Photocatalytic activity screening occurred on the gas-phase degradation of ethanol as a reference molecule, both under ultraviolet (UV) (6 h) and Light Emitting Diode (LED) (24 h) irradiation. Mn-doped TiO₂ reached a maximum ethanol degradation of 35% under visible light after 24 h for the sample containing 20% of Mn. Also, we found that an acidic pH increased both ethanol degradation and mineralization to CO₂, while an alkaline pH drastically slowed down the reaction. A strict correlation between photocatalytic results and physico-chemical characterizations of the synthesized powders were drawn.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nano8090686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164255PMC
September 2018

Comparison of Branched and Linear Perfluoropolyether Chains Functionalization on Hydrophobic, Morphological and Conductive Properties of Multi-Walled Carbon Nanotubes.

Nanomaterials (Basel) 2018 Mar 19;8(3). Epub 2018 Mar 19.

Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, I-20133 Milano, Italy.

The functionalization of multi-walled carbon nanotubes (MW-CNTs) was obtained by generating reactive perfluoropolyether (PFPE) radicals that can covalently bond to MW-CNTs' surface. Branched and linear PFPE peroxides with equivalent molecular weights of 1275 and 1200 amu, respectively, have been thermally decomposed for the production of PFPE radicals. The functionalization with PFPE chains has changed the wettability of MW-CNTs, which switched their behavior from hydrophilic to super-hydrophobic. The low surface energy properties of PFPEs have been transferred to MW-CNTs surface and branched units with trifluoromethyl groups, CF₃, have conferred higher hydrophobicity than linear units. Porosimetry discriminated the effects of PFPE functionalization on meso-porosity and macro-porosity. It has been observed that reactive sites located in MW-CNTs mesopores have been intensively functionalized by branched PFPE peroxide due to its low average molecular weight. Conductivity measurements at different applied pressures have showed that the covalent linkage of PFPE chains, branched as well as linear, weakly modified the electrical conductivity of MW-CNTs. The decomposed portions of PFPE residues, the PFPE chains bonded on carbon nanotubes, and the PFPE fluids obtained by homo-coupling side-reactions were evaluated by mass balances. PFPE-modified MW-CNTs have been characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), static contact angle (SCA), surface area, and porosity measurements.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/nano8030176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5869667PMC
March 2018

Simultaneous photodegradation of VOC mixture by TiO powders.

Chemosphere 2018 Feb 5;193:198-206. Epub 2017 Nov 5.

GranitiFiandre SpA, Via Ghiarola Nuova 119, 42014 Castellarano, Italy.

Volatile and semi volatile organic compounds' concentration have dramatically increased in indoor environments in recent years. UV light promotes titanium dioxide, which oxidises various molecules; however, most of the studies report the degradation of a single VOC. Here, we investigate the photo-oxidation of 17 molecules in mixture to have a realistic test of TiO efficacy. We compare P25, a nanometric catalyst, and 1077, a micrometric sample, that poses less health concerns. A proton-transfer-reaction mass spectrometer measured online the concentration of all the pollutants simultaneously. Aldehydes compete for the adsorption on both the catalyst's active sites and thus they degrade 70% and 55% with P25 and 1077 respectively. Considering the single pollutant oxidation, instead, aldehydes fully oxidize. Even though benzene is recalcitrant to degradation, P25 and 1077 reduced toluene's concentration to 97% and 96% in 55 min, respectively. Acetonitrile is refractory to photocatalysis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.chemosphere.2017.11.003DOI Listing
February 2018

Micro-sized TiO as photoactive catalyst coated on industrial porcelain grès tiles to photodegrade drugs in water.

Environ Sci Pollut Res Int 2018 Jul 27;25(21):20348-20353. Epub 2017 Apr 27.

GranitiFiandre SpA, Via Radici Nord 112, 42014, Castellarano, Italy.

Pharmaceutical compounds and their metabolites raise worrying questions because of their continuous release and lack of efficient removal by conventional wastewater treatments; therefore, they are being detected in groundwater, surface water and drinking water in increasing concentrations. Paracetamol and aspirin are two of the most commonly used drugs employed as fever reducer, analgesic and anti-inflammatory. They and their metabolites are very often found in river water, so their degradation is necessary in order to render water suitable for human consumption. The present work is focused on the comparison of the photocatalytic performance of industrial active grés porcelain tiles covered with a commercial micro-sized TiO by industrial process using either conventional spray deposition or innovative digital printing methods. The photodegradation of two commonly used drugs, namely aspirin and paracetamol, was investigated both individually and as a mixture, in both deionized and tap water. The results reveal the full conversion of the drugs and the significant role of the photocatalytic tiles in the mineralization processes leading to harmless inorganic species. In particular, the digitally printed tiles exhibited better photodegradation performance for both drugs compared to the spray deposited tiles. No deactivation was observed on both photocatalytic tiles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-017-9066-6DOI Listing
July 2018

In vitro biocompatibility of a ferrimagnetic glass-ceramic for hyperthermia application.

Mater Sci Eng C Mater Biol Appl 2017 Apr 23;73:778-787. Epub 2016 Dec 23.

Applied Science and Technology Department, Institute of Materials Physics and Engineering, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy. Electronic address:

Ferrimagnetic glass-ceramics containing magnetite crystals were developed for hyperthermia applications of solid neoplastic tissue. The present work is focused on in vitro evaluation of the biocompatibility of these materials, before and after soaking in a simulated body fluid (SBF). X-ray diffraction, scanning electron microscopy, atomic absorption spectrophotometry, X-ray photoelectron spectrometry and pH measurements were employed in glass-ceramic characterisation. The free-radical mediated reactivity of the glass-ceramic was evaluated by Electron Paramagnetic Resonance (EPR) spin trapping. Cell adhesion and proliferation tests were carried out by using 3T3 murine fibroblasts. Cytotoxicity was performed by qualitative evaluation of human bone osteosarcoma cells U2OS cell line. The results show that almost two times more 3T3 cells proliferated on the samples pre-treated in SBF, compared with the untreated specimens. Moreover a decrease of confluence was observed at 48 and 72h for U2OS cells exposed to the untreated glass-ceramic, while the powder suspensions of glass-ceramic pre-treated in SBF did not influence the cell morphology up to 72h of exposition. The untreated glass-ceramic exhibited Fenton-like reactivity, as well as reactivity towards formate molecule. After pre-treatment with SBF the reactivity towards formate was completely suppressed. The concentration of iron released into the SBF solution was below 0.1ppm at 37°C, during one month of soaking. The different in vitro behaviour of the samples before and after SBF treatment has been correlated to the bioactive glass-ceramic surface modifications as detected by morphological, structural and compositional analyses.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.msec.2016.12.105DOI Listing
April 2017

TiO Nanotubes Arrays Loaded with Ligand-Free Au Nanoparticles: Enhancement in Photocatalytic Activity.

ACS Appl Mater Interfaces 2016 Nov 4;8(45):31051-31058. Epub 2016 Nov 4.

Istituto per le Tecnologie della Costruzione (ITC-CNR) , via Lombardia, 49, San Giuliano Milanese, I-20098 Milan, Italy.

A new protocol to synthesize size-controlled Au nanoparticles (NPs) loaded onto vertically aligned anatase TiO nanotubes arrays (TNTAs) prepared by electrochemical anodization is reported. Ligand-free Au NPs (<10 nm) were deposited onto anatase TNTAs supports, finely tuning the Au loading by controlling the immersion time of the support into metal vapor synthesis (MVS)-derived Au-acetone solutions. The Au/TNTAs composites were characterized by electron microscopies (SEM, (S)TEM), X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. Their photocatalytic efficiency was evaluated in toluene degradation in air under ambient conditions without thermal or chemical postsynthetic treatments. The role of Au loadings was pointed out, obtaining a three times enhancement of the pristine anatase TNTAs activity with the best sample containing 3.3 μg Au cm.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.6b11436DOI Listing
November 2016

Fe-based heterogeneous catalysts for the Fischer-Tropsch reaction: Sonochemical synthesis and bench-scale experimental tests.

Ultrason Sonochem 2017 01 19;34:774-780. Epub 2016 Jul 19.

University of Illinois at Urbana-Champaign, School of Chemical Sciences, 505 S. Mathews Av., Urbana, IL 61801, USA.

The sonochemical synthesis of nanostructured materials owes its origins to the extreme conditions created during acoustic cavitation, i.e., the formation of localized hot spots in the core of collapsing bubbles in a liquid irradiated with high intensity ultrasound (US). In particular, in the present work a sonochemical synthesis has been investigated for the production of three different iron-based samples supported on SiO and loaded with different metals and promoters (10 %wt of Fe; 30 %wt of Fe; 30 %wt of Fe, 2 %wt of K and 3.75 %wt of Cu) active in the Fischer-Tropsch (FT) process. Sonochemically synthesized heterogeneous catalysts were characterized by BET, XRPD, TPR, ICP, CHN, TEM, SEM and then tested in a fixed bed FT-bench-scale rig fed with a mixture of H and CO at a H/CO molar ratio equal to 2, at activation temperatures of 350-400°C and reaction temperatures of 250-260°C. The experimental results showed that the ultrasonic samples are effective catalysts for the FT process. Notably, increasing the activation temperature increased CO conversion, while product selectivity did not diminish. All the sonochemically prepared samples presented in this work provided better catalytic results compared to the corresponding traditional FT impregnated catalysts.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2016.07.012DOI Listing
January 2017

Aspirin and paracetamol removal using a commercial micro-sized TiO catalyst in deionized and tap water.

Environ Sci Pollut Res Int 2017 May 21;24(14):12646-12654. Epub 2016 Oct 21.

GranitiFiandre SpA, Via Radici Nord 112, 42014, Castellarano, Italy.

Micro-sized TiO catalyst was employed to degrade pharmaceutical compounds, i.e. aspirin and paracetamol, two of the most widely used drugs, purchasable without prescription. Their active agents, acetylsalicylic acid and acetaminophen, are characterized by different substituent groups, linked to the aromatic ring, which affect both the photodegradation and mineralization processes. The experimental conditions highlight the relationship between the nature of the pristine molecules, their degradation mechanisms, their mutual interference and the water's role. The research started from model systems with a single pollutant to the mixture of them and finally by moving from deionized water to tap water.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11356-016-7781-zDOI Listing
May 2017

Copper NPs decorated titania: A novel synthesis by high energy US with a study of the photocatalytic activity under visible light.

Ultrason Sonochem 2016 Jul 15;31:295-301. Epub 2016 Jan 15.

GranitiFiandre SpA, Castellarano (MO), Italy.

The most important drawback of the use of TiO2 as photocatalyst is its lack of activity under visible light. To overcome this problem, the surface modification of commercial micro-sized TiO2 by means of high-energy ultrasound (US), employing CuCl2 as precursor molecule to obtain both metallic copper as well as copper oxides species at the TiO2 surface, is here. We have prepared samples with different copper content, in order to evaluate its impact on the photocatalytic performances of the semiconductor, and studied in particular the photodegradation in the gas phase of some volatile organic molecules (VOCs), namely acetone and acetaldehyde. We used a LED lamp in order to have only the contribution of the visible wavelengths to the TiO2 activation (typical LED lights have no emission in the UV region). We employed several techniques (i.e., HR-TEM, XRD, FT-IR and UV-Vis) in order to characterize the prepared samples, thus evidencing different sample morphologies as a function of the various copper content, with a coherent correlation between them and the photocatalytic results. Firstly, we demonstrated the possibility to use US to modify the TiO2, even when it is commercial and micro-sized as well; secondly, by avoiding completely the UV irradiation, we confirmed that pure TiO2 is not activated by visible light. On the other hand, we showed that copper metal and metal oxides nanoparticles strongly and positively affect its photocatalytic activity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2016.01.015DOI Listing
July 2016

AuRu/AC as an effective catalyst for hydrogenation reactions.

Phys Chem Chem Phys 2015 Nov 27;17(42):28171-6. Epub 2015 Mar 27.

Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy.

AuRu bimetallic catalysts have been prepared by sequential deposition of Au on Ru or vice versa obtaining different nanostructures: when Ru has been deposited on Au, a Au(core)-Ru(shell) has been observed, whereas the deposition of Au on Ru leads to a bimetallic phase with Ru enrichment on the surface. In the latter case, the unexpected Ru enrichment could be attributed to the weak adhesion of Ru on the carbon support, thus allowing Ru particles to diffuse on Au particles. Both structures result very active in catalysing the liquid phase hydrogenolysis of glycerol and levulinic acid but the activity, the selectivity and the stability depend on the structure of the bimetallic nanoparticles. [email protected]/AC core-shell structure mostly behaved as the monometallic Ru, whereas the presence of bimetallic AuRu phase in [email protected]/AC provides a great beneficial effect on both activity and stability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c5cp00632eDOI Listing
November 2015

Porous TiO2 microspheres with tunable properties for photocatalytic air purification.

Ultrason Sonochem 2013 Jan 20;20(1):445-51. Epub 2012 Jul 20.

CNR-Istituto di Scienze e Tecnologie Molecolari, Via Golgi 19, 20133 Milano, Italy.

The synthesis of highly-crystalline porous TiO(2) microspheres is reported using ultrasonic spray pyrolysis (USP) in the presence of colloidal silica as a template. We have exploited the interactions between hot SiO(2) template particles surface and TiO(2) precursor that occur during reaction inside the droplets, to control the physical and chemical properties of the resulting particles. Varying the SiO(2) to titanium precursor molar ratio and the colloidal silica dimension, we obtained porous titania microspheres with tunable morphology, porosity, BET surface area, crystallite size, band-gap, and phase composition. In this regard, we have also observed the preferential formation of anatase vs. rutile with increasing initial surface area of the silica template. The porous TiO(2) microspheres were tested in the photocatalytic degradation of nitrogen oxides (NO(x)) in the gas phase. USP prepared nanostructured titania samples were found to have significantly superior specific activity per surface area compared to a commercial reference sample (P25 by Evonik-Degussa).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2012.07.003DOI Listing
January 2013

"Wetting enhancer" pullulan coating for antifog packaging applications.

ACS Appl Mater Interfaces 2012 Jul 13;4(7):3692-700. Epub 2012 Jul 13.

DeFENS, Department of Food, Environmental and Nutritional Sciences, Packaging Division, University of Milan , Via Celoria 2, I - 20133 Milan, Italy.

A new antifog coating made of pullulan is described in this work. The antifog properties are discussed in terms of wettability, surface chemistry/morphology, and by quantitative assessment of the optical properties (haze and transparency) before and after fog formation. The work also presents the results of antifog tests simulating the typical storage conditions of fresh foods. In these tests, the antifog efficiency of the pullulan coating was compared with that of two commercial antifog films, whereas an untreated low-density polyethylene (LDPE) film was used as a reference. The obtained results revealed that the pullulan coating behaved as a "wetting enhancer", mainly due to the low water contact angle (∼24°), which in turn can be ascribed to the inherent hydrophilic nature of this polysaccharide, as also suggested by the X-ray photoelectron spectroscopy experiments. Unlike the case of untreated LDPE and commercial antifog samples, no discrete water formations (i.e., droplets or stains) were observed on the antifog pullulan coating on refrigeration during testing. Rather, an invisible, continuous and thin layer of water occurred on the biopolymer surface, which was the reason for the unaltered haze and increased transparency, with the layer of water possibly behaving as an antireflection layer. As confirmed by atomic force microscopy analysis, the even deposition of the coating on the plastic substrate compared to the patchy surfacing of the antifog additives in the commercial films is another important factor dictating the best performance of the antifog pullulan coating.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/am300784nDOI Listing
July 2012

Effect of nature and location of defects on bandgap narrowing in black TiO2 nanoparticles.

J Am Chem Soc 2012 May 24;134(18):7600-3. Epub 2012 Apr 24.

CNR-Istituto di Scienze e Tecnologie Molecolari, Via C. Golgi 19, Milano 20133, Italy.

The increasing need for new materials capable of solar fuel generation is central in the development of a green energy economy. In this contribution, we demonstrate that black TiO(2) nanoparticles obtained through a one-step reduction/crystallization process exhibit a bandgap of only 1.85 eV, which matches well with visible light absorption. The electronic structure of black TiO(2) nanoparticles is determined by the unique crystalline and defective core/disordered shell morphology. We introduce new insights that will be useful for the design of nanostructured photocatalysts for energy applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ja3012676DOI Listing
May 2012

Photocatalytic NOx abatement: the role of the material supporting the TiO2 active layer.

J Hazard Mater 2012 Apr 10;211-212:203-7. Epub 2011 Nov 10.

Università degli Studi di Milano, Dipartimento di Chimica Fisica ed Elettrochimica, Via Golgi 19, 20133 Milano, Italy.

The importance of the choice of a suitable substrate as supporting material for photoactive TiO(2), either in the form of powders or thin films or in photoactive paints, is frequently disregarded. In this paper four different supports (stainless steel, sand-blasted stainless steel, Teflon and glass) are object of investigation. The final aim is to verify the presence of interactions between the photocatalyst (AEROXIDE(®) TiO(2) P25 by Evonik Degussa Corporation) and the support, directly involved in the photocatalytic activity in the NO(x) abatement. The characterization results have been correlated with the photoactivity of the different samples. In particular, a coating of about 6-9 μm seems to allow a photocatalytic result free from any positive or negative interference with the supporting material, therefore giving reliable results about the photoactivity of the TiO(2) under investigation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2011.10.095DOI Listing
April 2012

Graphene oxide based Pt-TiO2 photocatalyst: ultrasound assisted synthesis, characterization and catalytic efficiency.

Ultrason Sonochem 2012 Jan 1;19(1):9-15. Epub 2011 Jun 1.

The School of Chemistry, University of Melbourne, Parkville, Melbourne, Victoria 3010, Australia.

An ultrasound-assisted method was used for synthesizing nanosized Pt-graphene oxide (GO)-TiO2 photocatalyst. The Pt-GO-TiO2 nanoparticles were characterized by diffused reflectance spectroscopy, X-ray diffraction, N2 BET adsorption-desorption measurements, atomic force microscopy and transmission electron microscopy. The photocatalytic and sonophotocatalytic degradation of a commonly used anionic surfactant, dodecylbenzenesulfonate (DBS), in aqueous solution was carried out using Pt-GO-TiO2 nanoparticles in order to evaluate the photocatalytic efficiency. For comparison purpose, sonolytic degradation of DBS was carried out. The Pt-GO-TiO2 catalyst degraded DBS at a higher rate than P-25 (TiO2), prepared TiO2 or GO-TiO2 photocatalysts. The mineralization of DBS was enhanced by a factor of 3 using Pt-GO-TiO2 compared to the P-25 (TiO2). In the presence of GO, an enhanced rate of DBS oxidation was observed and, when doped with platinum, mineralization of DBS was further enhanced. The Pt-GO-TiO2 catalyst also showed a considerable amount of degradation of DBS under visible light irradiation. The initial solution pH had an effect on the rate of photocatalytic oxidation of DBS, whereas no such effect of initial pH was observed in the sonochemical or sonophotocatalytic oxidation of DBS. The intermediate products formed during the degradation of DBS were monitored using electrospray mass spectrometry. The ability of GO to serve as a solid support to anchor platinum particles on GO-TiO2 is useful in developing new photocatalysts.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2011.05.018DOI Listing
January 2012

Sonophotocatalytic degradation of 4-chlorophenol using Bi2O3/TiZrO4 as a visible light responsive photocatalyst.

Ultrason Sonochem 2011 Jan 11;18(1):135-9. Epub 2010 Apr 11.

Particulate Fluids Processing Centre, School of Chemistry, University of Melbourne, Parkville, Melbourne, Victoria 3010, Australia.

The oxidative degradation of 4-chlorophenol (4-CP) by sonolytic, photocatalytic and sonophotocatalytic processes was studied in aqueous solutions using Bi(2)O(3)/TiZrO(4) as a visible light driven photocatalyst and with 20 kHz ultrasound. The results reveal that Bi(2)O(3)/TiZrO(4) is an efficient photocatalyst capable of degrading 4-CP by both photocatalytic and sonophotocatalytic processes. During the sonolysis of 4-CP solutions, HPLC results showed the formation of a number of intermediate products, whereas, no such intermediates were formed during the sonophotocatalytic degradation of 4-CP. TOC results showed rapid mineralization of 4-CP during the sonophotocatalytic degradation process, relative to that observed with sonolysis alone. The results reveal a clear advantage in using a coupled method for the oxidation of 4-CP and a cumulative effect was observed. Further, the solution pH had no specific influence on the sonophotocatalytic degradation of 4-CP, unlike the situation for sonolysis alone where the degradation rate decreased as the pH was raised from acidic to basic conditions. The combined sonophotocatalytic degradation process was found to be simple to apply and has the potential to be a powerful method for the remediation of organic contaminants present in water and wastewater.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ultsonch.2010.04.002DOI Listing
January 2011

Alkaline phosphatase grafting on bioactive glasses and glass ceramics.

Acta Biomater 2010 Jan 18;6(1):229-40. Epub 2009 Jun 18.

Department of Materials Science and Chemical Engineering, Politecnico di Torino, C. so Duca degli Abruzzi 24, Torino 10129, Italy.

Bone integration of orthopaedic or dental implants and regeneration of damaged bone at the surgical site are still unresolved problems in prosthetic surgery. For this reason, biomimetic surfaces (i.e. both inorganic and biological bioactive surfaces) represent a challenge for bone implantation. In this research work a hydrolase enzyme (alkaline phosphatase) was covalently grafted to inorganic bioactive glass and glass ceramic surfaces, in order to impart biological bioactivity. The functionalized samples were analysed by means of X-ray photoelectron spectroscopy in order to verify enzyme presence on the surface. Enzyme activity was measured by means of UV-visual spectroscopy after reaction with the natural substrate. Scanning electron microscopy-energy-dispersive spectroscopy observations allowed monitoring of the morphological and chemical modification of the materials during the different steps of functionalization. In vitro inorganic bioactivity was investigated by soaking samples in simulated body fluid. Enzymatic activity of the samples was tested and compared before and after soaking. Enzymatic activity of the solution was monitored at different experimental times. This study demonstrates that alkaline phosphatase could be successfully grafted onto different bioactive surfaces while maintaining its activity. Presence of the enzyme in vitro enhances the inorganic bioactivity of the materials tested.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.actbio.2009.06.025DOI Listing
January 2010

One-step synthesis and functionalization of hydroxyl-decorated magnetite nanoparticles.

J Colloid Interface Sci 2008 Jun 15;322(1):173-9. Epub 2008 Mar 15.

Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano, Italy.

Magnetite nanoparticles covered by a layer of omega-hydroxycarboxylic acid were synthesized in one step by high-temperature decomposition of iron(III) omega-hydroxycarboxylates in tri- and tetra-ethylene glycol. The nanoparticles were characterized by TEM, XRD, IR, XPS and NMR techniques in order to show that they comprise a crystalline magnetite core and actually bear on the outer surface terminal hydroxy groups. The latter ones are convenient "handles" for further functionalization as opposed to the chemically-inert aliphatic chains which cover conventionally synthesized nanoparticles. This was shown by several examples in which the hydroxy groups on the nanoparticle surface were easily transformed in other functional groups or reacted with other molecules. For instance, the hydroxyl-decorated nanoparticles were made water soluble by esterification with a PEGylated acetic acid. The reactive behavior of the surfactant monolayer was monitored by degrading the nanoparticles with aqueous acid and isolating the surfactant for NMR characterization. In general, the reactivity of the terminal hydroxyl groups on the nanoparticle surface parallels that observed in the free surfactants. The reported hydroxyl-decorated magnetite nanoparticles can be thus considered as pro-functional nanoparticles, i.e., a convenient starting material to functionalized magnetic nanoparticles.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcis.2008.03.008DOI Listing
June 2008

Photodegradation of Pollutants in Air: Enhanced Properties of Nano-TiO(2) Prepared by Ultrasound.

Nanoscale Res Lett 2008 Nov 25;4(2):97-105. Epub 2008 Nov 25.

Nanocrystalline TiO(2) samples were prepared by promoting the growth of a sol-gel precursor, in the presence of water, under continuous (CW), or pulsed (PW) ultrasound. All the samples turned out to be made of both anatase and brookite polymorphs. Pulsed US treatments determine an increase in the sample surface area and a decrease of the crystallite size, that is also accompanied by a more ordered crystalline structure and the samples appear to be more regular and can be considered to contain a relatively low concentration of lattice defects. These features result in a lower recombination rate between electrons and holes and, therefore, in a good photocatalytic performance toward the degradation of NO(x) in air. The continuous mode induces, instead, the formation of surface defects (two components are present in XPS Ti 2p(3/2) region) and consequently yields the best photocatalyst. The analysis of all the characterization data seems to suggest that the relevant parameter imposing the final features of the oxides is the ultrasound total energy per volume (E(tot)/V) and not the acoustic intensity or the pulsed/continuous mode.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11671-008-9208-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2894369PMC
November 2008

Efficiency of 1,4-dichlorobenzene degradation in water under photolysis, photocatalysis on TiO2 and sonolysis.

J Hazard Mater 2008 May 25;153(3):1136-41. Epub 2007 Sep 25.

Dipartimento di Chimica Fisica ed Elettrochimica and Center of Excellence CIMAINA, Università degli Studi di Milano, Via Golgi 19, I-20133 Milano, Italy.

The rate of 1,4-dichlorobenzene (1,4-DCB) degradation and mineralization in the aqueous phase was investigated either under direct photolysis or photocatalysis in the presence of commercial or sol-gel synthesized TiO2, or under sonolysis at 20 kHz with different power inputs. Two lamps, both emitting in the 340-400 nm wavelength range with different energy, were employed as irradiation sources. Photocatalysis ensured faster removal of 1,4-DCB with respect to sonolysis and direct photolysis. The highest degradation and mineralization rate was attained with the combined use of photocatalysis and sonolysis, i.e. under sonophotocatalytic conditions. The efficiency of the employed advanced oxidation techniques in 1,4-DCB degradation is discussed also in relation to their energy consumption, which might be decisive for their practical application.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jhazmat.2007.09.071DOI Listing
May 2008
-->