Electrochemical treatment coupled with solar light-driven photocatalytic approach: A challenging process in cascade for hydrogen production and wastewater remediation

This study presents an innovative approach for simultaneous hydrogen production and wastewater remediation, integrating electrochemical treatment with solar light-driven photocatalysis. The research focuses on the use of a noble metal-free cathode, based on a electrodeposited composite of Co2P and elemental P, for efficient hydrogen generation from simulated wastewater through water splitting. This composite is characterized, in its optimized form, by an overpotential equal to 133.6 mV (at 10 mA cm-2) and by a Tafel slope of 60.5 mV dec-1. Challenges like the high potential required for the Oxygen Evolution Reaction (OER) and the use of expensive noble metals in electrodes are addressed by employing earth-abundant compounds for electrode fabrication. Additionally, the study explores the degradation of diclofenac (DCF) in wastewater, demonstrating that electrochemical treatment alone is insufficient for organic matter removal. Therefore, a coupled process involving a first electrochemical treatment step followed by a photocatalytic process using BiOCl is proposed. Thanks to the exposure of the (110) active face, BiOCl possesses excellent photocatalytic performances even under solar light irradiation. This hybrid approach not only enhances the efficiency of DCF degradation (about 90%) and reaches an organic matter removal of 59%, but it also improves hydrogen production, offering a sustainable solution for energy generation and water purification in the face of increasing global industrialization and water scarcity

A New Frontier of Photocatalysis Employing Micro-Sized TiO2: Air/Water Pollution Abatement and Self-Cleaning/ Antibacterial Applications

This chapter presents the use of a commercial micro-sized TiO2 powder as an alternative to the traditional nano-powders as semiconductors in photocatalytic processes. Results of the photocatalytic efficiency towards the photodegradation of the traditional pollutant molecules both in gas phase (nitrogen oxides (NOx) and volatile organic compounds (VOCs)) and in water phase (phenol) are presented and compared to the results obtained with two nano-sized reference powders. Micro-sized TiO2 is also industrially coated at the surfaces of porcelain grés tiles (Active Clean Air and Antibacterial Ceramic™). The possibility to have a photocatalytic material, strongly stuck at the surface of a vitrified tile, increases the use of photocatalysis in real conditions: no problem of filtration of the semiconductor from the liquid medium after use and no risks of leakage of nanoparticles in the atmosphere. Tests were performed using reactors equipped with UV-A lamps and with suitable analytical systems, depending on the final purpose. Characterization data from both powders and coated tiles are put in correlation with the photocatalytic results to understand the semiconductor action during the photocatalytic process. Polluting molecules were chosen in order to cover all the common aspects of environmental pollution: NOx and some VOCs represent the model molecules to test the efficiency of the micro-sized TiO2 (degradation from the pristine molecule to CO2 or inorganic salts) in gas phase. As for the water pollution, phenol was chosen as common pollutant in worldwide rivers. Moreover, tests on self-cleaning and antibacterial properties are also reported. The positive results of micro-sized TiO2 both in powder and coated onto the surface of porcelain grés tiles open the way to new photocatalytic products that do not make use of nanoscale powders avoiding problems to human safety caused by the inherent toxicity of the nanoparticles

Noble Metal Promoted TiO2 from Silver-Waste Valorisation: Synergism between Ag and Au

Wastewaters from precious metal industries contain high amounts of noble metals, but their efficient recycling is hindered by the wastewater complex composition. Here, we propose an innovative approach for the efficient recovery of noble metals contained in these metal-enriched wastewaters as precursors for the synthesis of noble metal nanoparticles (NPs) and supported metal catalysts. Silver NPs were synthesized from Ag-enriched wastewater and then deposited on TiO2 to prepare photocatalysts. Then, further promotion of the photocatalytic activity of Ag-modified TiO2 was achieved by the addition of as little as 0.5 wt.% of Au. STEM-EDS analyses proved that Au NPs were located on Ag or AgOx nanoparticles. The contact between the two metal-containing NPs results in charge transfer effects, appreciable both in terms of oxidation states determined by XPS and of optical properties. In particular, the plasmon band of Au NPs shows photochromic effects: under UV light irradiation, bimetallic samples exhibit a blue-shift of the plasmon band, which is reversible under dark storage. The activity of the materials was tested towards ethanol photodegradation under UV light. Adding 0.5 wt.% Au NPs resulted in a promoted activity compared to Ag-TiO2, thus showing synergistic effects between Au and Ag. Ethanol was completely converted already after 1 h of UV irradiation, acetaldehyde was formed as the main oxidation product and fully degraded in less than 180 min. Notably, bimetallic samples showed ethylene formation by a parallel dehydration mechanism

Photocatalytic TiO2: From Airless Jet Spray Technology to Digital Inkjet Printing

TiO2 powders can be employed as both photocatalytic and structural materials, leading to applications in external coatings or in interior furnishing devices, including cement mortar, tiles, floorings, and glass supports. The technology of photocatalytic building materials is connected with the widespread production of photocatalytic active tiles. All the techniques proposed in the study involve the employment of nanosized TiO2: this represents a new problem to be dealt with, as inhaling nanoparticles exposes workers during industrial production and people in everyday locations to their dangerousness. Only very recently the employment of microsized TiO2 has been proposed, and the authors in this manuscript report the use of micrometric titania materials, but employing a new deposition technique, which is digital inkjet printing. It represents an improvement of the classical spray coating methods, as it requires piezoelectric heads to precisely direct the deposition of the suspension with an electrostatic field. The mixture contains aqueous/organic components containing micrometric TiO2: to form a suspension, which is printed onto the surface of porcelain grès, large slabs using a digital printer. Many advantages are immediately evident, namely rapid and precise deposition, (almost) no waste of raw materials, thereby highlighting the economy, environmental friendliness, and sustainability of the process. All the materials we obtained have been thoroughly characterized by means of several experimental physico-chemical techniques, such as Raman microspectroscopy and scanning electron microscopy coupled with elemental analysis. Two different model VOCs, ethanol and toluene, and NOx have been selected to test the photocatalytic performances of the abovementioned tiles. Moreover, the antibacterial properties of the tiles have been determined, using Escherichia coli as example. Life cycle assessments (LCAs) for the two processes were modeled for 1 m2 of tiles produced in Modena, Italy. The impact assessments revealed that jet spraying exhibited uniformly greater impacts than digital inkjet printing and that the principal impacts were in human toxicity, cancer effects, freshwater ecotoxicity, and climate change. Most of the impacts were associated with the energy required for the production processes. Further considerations revealed that jet spraying is projected to generate twice as much CO2 and 30% more NOx than digital inkjet printing

Networks of microstructural damage predict disability in multiple sclerosis

Background: Network-based measures are emerging MRI markers in multiple sclerosis (MS). We aimed to identify networks of white (WM) and grey matter (GM) damage that predict disability progression and cognitive worsening using data-driven methods. // Methods: We analysed data from 1836 participants with different MS phenotypes (843 in a discovery cohort and 842 in a replication cohort). We calculated standardised T1-weighted/T2-weighted (sT1w/T2w) ratio maps in brain GM and WM, and applied spatial independent component analysis to identify networks of covarying microstructural damage. Clinical outcomes were Expanded Disability Status Scale worsening confirmed at 24 weeks (24-week confirmed disability progression (CDP)) and time to cognitive worsening assessed by the Symbol Digit Modalities Test (SDMT). We used Cox proportional hazard models to calculate predictive value of network measures. // Results: We identified 8 WM and 7 GM sT1w/T2w networks (of regional covariation in sT1w/T2w measures) in both cohorts. Network loading represents the degree of covariation in regional T1/T2 ratio within a given network. The loading factor in the anterior corona radiata and temporo-parieto-frontal components were associated with higher risks of developing CDP both in the discovery (HR=0.85, p<0.05 and HR=0.83, p<0.05, respectively) and replication cohorts (HR=0.84, p<0.05 and HR=0.80, p<0.005, respectively). The decreasing or increasing loading factor in the arcuate fasciculus, corpus callosum, deep GM, cortico-cerebellar patterns and lesion load were associated with a higher risk of developing SDMT worsening both in the discovery (HR=0.82, p<0.01; HR=0.87, p<0.05; HR=0.75, p<0.001; HR=0.86, p<0.05 and HR=1.27, p<0.0001) and replication cohorts (HR=0.82, p<0.005; HR=0.73, p<0.0001; HR=0.80, p<0.005; HR=0.85, p<0.01 and HR=1.26, p<0.0001). // Conclusions: GM and WM networks of microstructural changes predict disability and cognitive worsening in MS. Our approach may be used to identify patients at greater risk of disability worsening and stratify cohorts in treatment trials

Mineralisation of surfactants using ultrasound and the Advanced Fenton Process

The destruction of the surfactants, sodium dodecylbenzene sulfonate (DBS) and dodecyl pyridinium chloride (DPC), using an advanced oxidation process is described. The use of zero valent iron (ZVI) and hydrogen peroxide at pH = 2.5 (the advanced Fenton process), with and without, the application of 20 kHz ultrasound leads to extensive mineralisation of both materials as determined by total organic carbon (TOC)measurements. For DBS, merely stirring with ZVI and H2O2 at 20°C leads to a 51% decrease in TOC, but using 20 kHz ultrasound at 40°C, maintaining the pH at 2.5 throughout and adding extra amounts of ZVI and H2O2 during the degradation, then the extent of mineralisation of DBS is substantially increased to 93%. A similar result is seen for DPC where virtually no degradation occurs at 20°C, but if extra amounts of both ZVI and hydrogen peroxide are introduced during the reaction at 40°C and the pH is maintained at 2.5, then an 87% mineralisation of DPC is obtained. The slow latent remediation of both surfactants and the mechanism of degradation are also discussed

The role of sol–gel chemistry in the low-temperature formation of ZnO buffer layers for polymer solar cells with improved performance

A new approach is proposed in this work to chemically control the low-temperature sol-gel formation of ZnO thin films used as efficient electron transporting layers (ETLs) in inverted polymer solar cells (PSCs). The chemical composition of the ZnO sol-gel precursor was modified by systematically employing different [H2O]/[Zn2+] molar ratios in the starting sol formulation and evaluating their influence on film properties and PSC device performance. A thorough characterization of the obtained ZnO ETLs evidenced the key importance of the [H2O]/[Zn2+] molar ratio to achieve effective control on the sol-gel hydrolysis and condensation processes. Based on these evidences, a mechanism for the formation of the ZnO films at the low processing temperatures used in this work was proposed. PSC devices were fabricated incorporating ZnO ETLs obtained from ZnO sol precursor formulations with increasing [H2O]/[Zn2+] ratios and their photovoltaic characterization revealed the presence of a maximum device efficiency for intermediate [H2O]/[Zn2+] values. Finally, the effect of water in the ZnO sol precursor on the long-term (>1000 h) shelf-life of PSCs fabricated onto flexible PET substrates was investigated and a correlation was found between chemical composition of the ZnO sol precursor and device shelf-life. The results of this study give a clear demonstration of a viable strategy to achieve improved PSC device performance by chemically controlling the formation of the sol-gel based ZnO ETL at processing temperatures compatible with flexible plastic substrates and provide useful guidelines for the development of efficient sol-gel derived metal-oxide buffer layers for highly performing flexible photovoltaics

Mesenchymal stem cells in renal function recovery after acute kidney injury. Use of a differentiating agent in a rat model.

Acute kidney injury (AKI) is a major health care condition with limited current treatment options. Within this context, stem cells may provide a clinical approach for AKI. Moreover, a synthetic compound previously developed, hyaluronan monoesters with butyric acid (HB), able to induce metanephric differentiation, formation of capillary-like structures, and secretion of angiogenic cytokines, was tested in vitro. Thereafter, we investigated the effects of human mesenchymal stem cells from fetal membranes (FMhMSCs), both treated and untreated with HB, after induction of ischemic AKI in a rat model. At reperfusion following 45-min clamping of renal pedicles, each rat was randomly assigned to one of four groups: CTR, PBS, MSC, and MSC-HB. Renal function at 1, 3, 5, and 7 days was assessed. Histological samples were analyzed by light and electron microscopy and renal injury was graded. Cytokine analysis on serum samples was performed. FMhMSCs induced an accelerated renal functional recovery, demonstrated by biochemical parameters and confirmed by histology showing that histopathological alterations associated with ischemic injury were less severe in cell-treated kidneys. HB-treated rats showed a minor degree of inflammation, both at cytokine and TEM analyses. Better functional and morphological recovery were not associated to stem cells' regenerative processes, but possibly suggest paracrine effects on microenvironment that induce retrieval of renal damaged tissues. These results suggest that FMhMSCs could be useful in the treatment of AKI and the utilization of synthetic compounds could enhance the recovery induction ability of cells

Bismuth oxyhalides for NOx degradation under visible light: the role of the chloride precursor

ABSTRACT: Photocatalysis is a green technology for tackling water and air contamination. A valid alternative to the most exploited photocatalytic material, TiO2, is bismuth oxyhalides, which feature a wider bandgap energy range and use visible radiation to attain photoexcitation. Moreover, their layered structure favors the separation of photogenerated electron–hole pairs, with an enhancement in photocatalytic activity. Controlled doping of bismuth oxyhalides with metallic bismuth nanoparticles allows for further boosting of the performance of the material. In the present work, we synthesized Y%Bi-doped BiO(Cl0.875Br0.125) (Y = 0.85, 1, 2, 10) photocatalysts, using cetyltrimethylammonium bromide as the bromide source and varying the chloride source to assess the impact that both length and branching of the hydrocarbon chain might have on the framing and layering of the material. A change in the amount of the reducing agent NaBH4 allowed tuning of the percentage of metallic bismuth. After a thorough characterization (XRPD, SEM, TEM, UV-DRS, XPS), the photocatalytic activity of the catalysts was tested in the degradation of NOx under visible light, reaching a remarkable 53% conversion after 3 h of illumination for the material prepared using cetylpyridinium chloride