Search Results (14)

Cytotoxic antibiotics (CA) present a pressing environmental concern due to their persistence and potential adverse effects on ecosystems and human health. Conventional wastewater treatment methods often fail to effectively remove these compounds, making it necessary to explore advanced oxidation processes (AOPs) as promising alternatives. This review aims to synthesize global data on the dosages and environmental concentrations of common CA in diverse water sources, while evaluating the efficacy of AOPs in degrading these contaminants. Various AOPs, including photocatalysis, ozonation, and Fenton-like processes, or their combination, are discussed, highlighting their mechanisms and efficiency in eliminating cytotoxic antibiotics from aqueous environments. In addition, information about the degradation by-products is provided. The rising consumption of cytotoxic drugs underscores the need for this up-to-date review, as diseases were CA are used as treatment, show increasing numbers. By consolidating recent developments and outlining challenges and opportunities, this review serves as a valuable resource for researchers, engineers, and policymakers involved in mitigating the environmental impact of cytotoxic antibiotics through AOPs. Full article

Natural weathering of carbonate building surfaces exposed to outdoor conditions can be effectively tackled by appropriate products. The aim of this experimental study was to evaluate the effectiveness of nano-zirconia (n-ZrO₂) as a consolidant for calcite surfaces. Sorption kinetics were investigated in batch experiments by applying aqueous dispersions of n-ZrO₂ onto model, crushed Apuan marble samples of different bead sizes. Adsorption and desorption by the action of simulated rainwater as an environmentally relevant leaching solution were investigated. Adsorption studies revealed a good chemical affinity between n-ZrO₂ and calcite, while desorption resulted in <6% release of n-ZrO₂ and 100-fold lower solubility for 1 mm-sized beads compared to controls. These results suggest that n-ZrO₂ may adsorb efficiently to calcite and protect the surface from dissolution. The results of further tests performed on artificially aged and consolidated samples of Apuan marble indicate that the application of n-ZrO₂ only moderately affects water vapor permeability, water absorption coefficient, and drying behaviour. Therefore, no harmful effects are expected from the treatment. Micromechanical tests showed slightly increased mechanical strength after treatment. The obtained results highlight the effectiveness of n-ZrO₂ as a surface consolidant and protective agent for calcite. Full article

In this work, nanocellulose aqueous dispersions were studied as a bio-inspired consolidating agent for the recovery and conservation of ancient wood and compared with two of the most used traditional consolidants: the synthetic resins Paraloid B-72 and Regalrez 1126. The morphology of crystalline nanocellulose (CNC), determined using Scanning Electron Microscopy (SEM), presents with a rod-like shape, with a size ranging between 15 and 30 nm in width. Chemical characterization performed using the Fourier-Transform Infrared Spectroscopy (FT-IR) technique provides information on surface modifications, in this case, demonstrating the presence of only the characteristic peaks of nanocellulose. Moreover, conductometric, pH, and dry matter measurements were carried out, showing also in this case values perfectly conforming to what is found in the literature. The treated wood samples were observed under an optical microscope in reflected light and under a scanning electron microscope to determine, respectively, the damage caused by xylophages and the morphology of the treated surfaces. The images acquired show the greater similarity of the surfaces treated with nanocellulose to untreated wood, compared with other consolidating agents. Finally, a colorimetric analysis of these samples was also carried out before and after a first consolidation treatment, and after a second treatment carried out on the same samples three years later. The samples treated with CNC appeared very homogeneous and uniform, without alterations in their final color appearance, compared to other traditional synthetic products. Full article

Consolidation of mural paintings in hypogea is challenging because of their severe microclimatic conditions, characterized by high humidity levels, low air circulation, the presence of salts efflorescence, and the detrimental growth of biodeteriogen agents. Traditional consolidant products show significant drawbacks when used in hypogeum. Organic compounds, such as acrylic emulsions, are bio-receptive and some inorganic consolidants, such as silica-based products, show a lack of compatibility with the original substrate, which could lead to a reduction in permeability and an increase in the mechanical resistance of the external layer. The presence of solvents in their formulations, particularly short-chain alcohols that can activate germination of fungal spores, leads to the release of great amounts of volatile organic compounds, which are particularly harmful in the hypogeic environment. To solve these problems, restorers of the Istituto Centrale per il Restauro (ICR) decided to use a new aqueous nanolime dispersion, NANOLAQ, consisting of pure and crystalline Ca(OH)₂ nanoparticles dispersed in water, produced by an innovative and sustainable patented procedure. After laboratory testing, the product has been applied on site, on a medieval mural painting in the Ss. Peter and Paul hypogeum in the UNESCO site of Matera (Italy), monitoring the performance in terms of cohesion of the paint layer and preservation of aesthetic features. Full article

Aqueous solutions of diammonium hydrogen phosphate (DAP) have been recently proposed for consolidation of archeological bones, as an alternative to traditional products. Here, we investigated several routes to improve the performance of the DAP-based treatment, namely increasing the DAP concentration, adding calcium ions and adding ethanol to the DAP solution. Archaeological bones dated to about 1–0.8 million years ago were used for the tests. After preliminary screening by FTIR microscopy and FEG-SEM among different formulations, confirming the formation of new hydroxyapatite phases, the most promising formulation was selected, namely a 3 M DAP solution. The strengthening ability of this formulation was systematically compared to that of the most widely used commercial consolidant, namely Paraloid B72. The performance of the two treatments was evaluated in terms of Knoop and Vickers microhardness, resistance to scratch and resistance to material loss by peeling off. The results of the study show that the DAP treatment was able to improve the bone surface properties and also the resistance to material loss by peeling off, which is more dependent on in-depth consolidation. Paraloid B72 led to the formation of a layer of acrylic resin on the bone surface, which influenced the mechanical tests. Nonetheless, Paraloid B72 was able to penetrate in depth and substantially decrease the material loss by peeling off, even more effectively than DAP. The results of this study indicate that the potential of the DAP treatment for bone consolidation is confirmed. Full article

In this work, the consolidation efficiency of SiO₂ nanoparticles (synthesized in the Chemistry laboratories at the Tor Vergata University of Roma) was tested on Pietraforte sandstone surfaces belonging to the bell tower of San Lorenzo (Florence, Italy) and was fully investigated. Nanoparticles (synthesized in large-scale mass production) have been characterized by XRD—X-Ray Diffraction; Raman and FTIR—Fourier Transform Infrared spectroscopy; SEM—Scanning Electron Microscopy; while the Pietraforte sandstone morphology was examined by Porosimetry, capillary absorption test, surface hardness test, drilling resistance and tensile strength. The colorimetric measurements were also performed to characterize the optical modification exhibited by Pietraforte sandstones, especially after the SiO₂ treatments. Our results show that applying to the Pietraforte, the new consolidating agent based on SiO₂ nanoparticles, has several advantages, as they are more resistant to perforation, wear, and abrasion even long range (for long times of exposure and consolidating exercise against Florentine sandstone), compared to the CaCO₃ nanoparticles (tested in our previous paper), which instead show excellent performance but only close to their first application. This means that over time, their resistance to drilling decreases, they wear much more easily (compared to SiO₂-treated sandstone), and tend to exhibit quite a significant surface abrasion phenomena. The experimental results highlight that the SiO₂ consolidation efficiency on this kind of Florentine Pietraforte sandstone (having low porosity and a specific calcitic texture) seems to be higher in terms of water penetration protection, superficial cohesion forces, and an increase in surface resistance. Comparing the performance of SiO₂ nanoparticles with commercial consolidants in solvents such as Estel 1000 (tested here), we demonstrate that: (A) the restorative effects are obtained with a consolidation time over one week, significantly shorter when compared to the times of Estel 1000, exceeding 21 days; (B) SiO₂ nanoparticles perform better than Estel 1000 in terms of cohesion forces, also ensuring excellent preservation of the optical and color properties of the parent rock (without altering it after application). Full article

Butvar B-98 and PDMS-OH both have a demonstrable ability as consolidants for archaeological wood. This makes them both potential treatment options for the Oseberg collection, which is one of the most important archaeological finds from the Viking era. Both Butvar B-98 and PDMS-OH are soluble in organic solvents, offering a useful alternative to aqueous-based consolidants. Extensive characterisation studies were carried out on both of these polymers, with the use of analytical ultracentrifugation and viscometry, for the benefit of conservators wanting to know more about the physical properties of these materials. Short column sedimentation equilibrium analysis using SEDFIT-MSTAR revealed a weight-average molar mass (weight-average molecular weight) M_w of (54.0 ± 1.5) kDa (kg · mol⁻¹) for Butvar B-98, while four samples of PDMS-OH siloxanes (each with a different molar mass) had an M_w of (52.5 ± 3.0) kDa, (38.8 ± 1.5) kDa, (6.2 ± 0.7) kDa and (1.6 ± 0.1) kDa. Sedimentation velocity confirmed that all polymers were heterogeneous, with a wide range of molar masses. All molecular species showed considerable conformational asymmetry from measurements of intrinsic viscosity, which would facilitate networking interactions as consolidants. It is anticipated that the accumulated data on these two consolidants will enable conservators to make a more informed decision when it comes to choosing which treatment to administer to archaeological artefacts. Full article

In recent years, silk fibroin nanoparticles (SFNs) have been consolidated as drug delivery systems (DDSs) with multiple applications in personalized medicine. The design of a simple, inexpensive, and scalable preparation method is an objective pursued by many research groups. When the objective is to produce nanoparticles suitable for biomedical uses, their sterility is essential. To achieve sufficient control of all the crucial stages in the process and knowledge of their implications for the final characteristics of the nanoparticles, the present work focused on the final stage of sterilization. In this work, the sterilization of SFNs was studied by comparing the effect of different available treatments on the characteristics of the nanoparticles. Two different sterilization methods, gamma irradiation and autoclaving, were tested, and optimal conditions were identified to achieve the sterilization of SFNs by gamma irradiation. The minimum irradiation dose to achieve sterilization of the nanoparticle suspension without changes in the nanoparticle size, polydispersity, or Z-potential was determined to be 5 kiloGrays (kGy). These simple and safe methods were successfully implemented for the sterilization of SFNs in aqueous suspension and facilitate the application of these nanoparticles in medicine. Full article

Thermoelectric materials enable the direct conversion between heat and electricity. SnTe is a promising candidate due to its high charge transport performance. Here, we prepared SnTe nanocomposites by employing an aqueous method to synthetize SnTe nanoparticles (NP), followed by a unique surface treatment prior NP consolidation. This synthetic approach allowed optimizing the charge and phonon transport synergistically. The novelty of this strategy was the use of a soluble PbS molecular complex prepared using a thiol-amine solvent mixture that upon blending is adsorbed on the SnTe NP surface. Upon consolidation with spark plasma sintering, SnTe-PbS nanocomposite is formed. The presence of PbS complexes significantly compensates for the Sn vacancy and increases the average grain size of the nanocomposite, thus improving the carrier mobility. Moreover, lattice thermal conductivity is also reduced by the Pb and S-induced mass and strain fluctuation. As a result, an enhanced ZT of ca. 0.8 is reached at 873 K. Our finding provides a novel strategy to conduct rational surface treatment on NP-based thermoelectrics. Full article

In this study, novel and cost-effective alkali-activated materials (AAMs) for catalytic applications were developed by using an industrial side stream, i.e., blast furnace slag (BFS). AAMs can be prepared from aluminosilicate precursors under mild conditions (room temperature using non-hazardous chemicals). AAMs were synthesized by mixing BFS and a 50 wt % sodium hydroxide (NaOH) solution at different BFS/NaOH ratios. The pastes were poured into molds, followed by consolidation at 20 or 60 °C. As the active metal, Fe was impregnated into the prepared AAMs by ion exchange. The prepared materials were examined as catalysts for the catalytic wet peroxide oxidation (CWPO) of a bisphenol A (BPA) aqueous solution. As-prepared AAMs exhibited a moderate surface area and mesoporous structure, and they exhibited moderate activity for the CWPO of BPA, while the iron ion-exchanged, BFS-based catalyst (Fe/BFS30-60) exhibited the maximum removal of BPA (50%) during 3 h of oxidation at pH 3.5 at 70 °C. Therefore, these new, inexpensive, AAM-based catalysts could be interesting alternatives for catalytic wastewater treatment applications. Full article

Microencapsulation procedures have recently focused attention on designing novel microspheres via green synthesis strategies. The use of chitosan (CS) as an encapsulating material has increased interest due to its unique bioactive properties and the various crosslinking possibilities offered by their functional groups. The consolidation of the microspheres by physical crosslinking using sodium tripolyphosphate (TPP) combined with chemical crosslinking using vanillin (VA) open new opportunities in the framework of green dual crosslinking strategies. The developed strategy, a straightforward technique based on an aqueous medium avoiding complex separation/washing steps, offers advantages over the processes based on VA, mostly using water-in-oil emulsion approaches. Thus, in this work, the combination of TPP crosslinking (3, 5, and 10 wt.%) via spray-coagulation technique with two VA crosslinking methods (in situ and post-treatment using 1 wt.% VA) were employed in the preparation of microspheres. The microspheres were characterized concerning morphology, particle size, physicochemical properties, thermal stability, and swelling behavior. Results revealed that the combination of 5 wt.% TPP with in situ VA crosslinking led to microspheres with promising properties, being an attractive alternative for natural bioactives encapsulation due to the green connotations associated with the process. Full article

The intensive mechanical stirring of suspensions of recycled glass and inorganic waste powders in ‘weakly alkaline’ aqueous solutions (e.g., 2.5–3 NaOH), followed by viscous flow sintering at 800–1000 °C, easily yields highly porous glass-ceramic foams. The firing determines just the consolidation of powders with concurrent incorporation of pollutants from iron-rich waste, such as fly ash from coal combustion (FA). Engineered mixtures allow for the obtainment of chemically stable foams from treatments in air. Treatments in nitrogen are even more significant since they extend the conditions for stabilization and promote novel functionalities. In addition, the change in the atmosphere favors the formation of magnetite (Fe₃O₄), in turn enabling ultra-high dielectric permittivity and semiconductivity. Such a condition was further evidenced by preliminary tests on recycled glass combined with residues from the Bayer processing of aluminum ores or red mud (RM). Full article

External surfaces of stones used in historic buildings often carry high artistic value and need to be preserved from the damages of time, especially from the detrimental effects of the weathering. This study aimed to test the effectiveness and compatibility of some new environmentally-friendly materials for stone consolidation, as the use thereof has been so far poorly investigated. The treatments were based on combinations of an aqueous solution of di-ammonium phosphate (DAP) and two calcium-based nanomaterials, namely a commercial nanosuspension of Ca(OH)₂ and a novel nanosuspension of calcite. The treatments were applied to samples of two porous stones: a limestone and a sandstone. The effectiveness of the treatments was assessed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, ultrasound pulse velocity test, colour measurements, and capillary water absorption test. The results suggest that the combined use of DAP and Ca-based nanosuspensions can be advantageous over other commonly used consolidants in terms of retreatability and physical-chemical compatibility with the stone. Some limitations are also highlighted, such as the uneven distribution and low penetration of the consolidants. Full article

The present paper reviews the methods and the performance of in situ formation of calcium phosphates (CaP) for the conservation of materials belonging to cultural heritage. The core idea is to form CaP (ideally hydroxyapatite, HAP, the most stable CaP at pH > 4) by reaction between the substrate and an aqueous solution of a phosphate salt. Initially proposed for the conservation of marble and limestone, the treatment has been explored for a variety of different substrates, including sandstones, sulphated stones, gypsum stuccoes, concrete, wall paintings, archaeological bones and paper. First, the studies aimed at identifying the best treatment conditions (e.g., nature and concentration of the phosphate precursor, solution pH, treatment duration, ionic and organic additions to the phosphate solution, mineralogical composition of the new CaP phases) are summarized. Then, the treatment performance on marble and limestone is reviewed, in terms of protective and consolidating effectiveness, compatibility (aesthetic, microstructural and physical) and durability. Some pilot applications in real case studies are also reported. Recent research aimed at extending the phosphate treatment to other substrates is then illustrated. Finally, the strengths of the phosphate treatment are summarized, in comparison with alternative products, and some aspects needing future research are outlined. Full article