Diffuse Reflectance Spectrophotometry Research Articles

Highly efficient magnesium ferrite/graphene nano-heterostructure for visible-light photocatalytic applications: Experimental and first-principles DFT studies

In this research study, the electronic structure of magnesium ferrite/graphene (MFO/Gr) nano-heterostructure for photocatalytic application was studied. The MFO nanoparticles with a median size of 85 nm were composited with Gr sheets using a photo-assisted reduction process. The XRD and SAED results, respectively, showed the spinal crystalline structure of MFO and the hexagonal structure of Gr in MFO/Gr nanocomposite. The XPS results revealed that the orbitals of MFO and Gr atoms interacted with each other, implying a Van der Waals heterojunction nanocomposite. The optical characteristics using UV–Vis diffuse reflectance spectrophotometry (UV–Vis DRS) and photoluminescence (PL) spectra demonstrated a lowering of MFO band gap from 2.05 to 1.84 eV by incorporation of Gr. Furthermore, the photoelectrocatalytic and photocatalytic dye degradation examinations showed a substantial impact of Gr on the photocatalytic activity of MFO nanoparticles: a 28-fold increase in the photocurrent and an 8-fold increase in the dye-degradation rate. The density functional theory (DFT) studies on MFO/Gr heterojunction revealed a considerable hybridization between Gr atoms orbitals (2p orbitals) and MFO atoms orbitals (Mg 3 s and Fe 3d orbitals) in the conduction band, which facilitate the transfer of photo-excited electrons from MFO to Gr. Also, the charge density difference at the MFO/Gr interface led to a polarized field at the interface, which is desirable for hindering photogenerated electron-hole recombination in the MFO/Gr nanocomposite. Along with the experimental results, the DFT results also revealed that the MFO/Gr nano-heterostructure is an excellent candidate for photocatalytic applications such as water splitting using sunlight to produce green hydrogen fuel.

Solvothermal preparation of CuO/g-C3N4 and photocatalytic degradation of ciprofloxacin

Composite materials CuO/g-C3N4 (CuOCN) were prepared using a solvothermal method to investigate their degradation effect on ciprofloxacin (CIP). The materials were characterized through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectrophotometry (DRS), and X-ray photoelectron spectroscopy (XPS). The toxicity of degradation products of CIP was assessed through antibacterial experiments, and the degradation mechanism of CIP was investigated using quenching agent capture and high-performance liquid chromatography-mass spectrometry (HPLC-MS). The results of XRD and FTIR indicate that the CuOCN composite has been successfully synthesized. The photocatalytic experiment shows that adding 15% (w/w) of Cu3(BTC)2(H2O)3 in melamine (CuOCN2) has a relatively good degradation effect on CIP and can be reused multiple times. The TEM results indicate that both CuO and g-C3N4 have a layered structure and are attached together. HRTEM analysis reveals that the two components in CuOCN2 are arranged in a layered structure, with CuO displaying two crystal planes. Energy Dispersive Spectrometer (EDS) analysis reveals that the proportion of CuO in the three composite materials is 7.86% (w/w), 15.93% (w/w), and 84.83% (w/w), respectively. DRS detection reveals that the greater the amount of CuO added, the broader the visible light absorption range of the composite material, and the narrower the bandgap width. The photocurrent and photoresistance indicate that CuOCN2 exhibits a good photoelectric effect. XPS analysis shows that the CuOCN2 composite material possesses both the chemical composition and structure of CuO and g-C3N4. During the catalytic degradation process of CIP, four active substances, h+, e−, ·O2 −, and ·OH, were produced, leading to a reduction in the toxicity of the degradation products. Through HPLC-MS analysis, it was found that CIP undergoes reactions such as defluorination, ring opening of piperazine, and quinolone during degradation, resulting in reduced toxicity. This study provides an experimental basis for the degradation of CIP by CuOCN2.

Metal-free adsorption and photodegradation methods for methylene blue dye removal using different reduction grades of graphene oxide

The release of organic pollutants and dyes into the environment by industries has had profound and harmful effects on both humans and ecosystems. Graphene oxide (GO) and its reduced form have been investigated for their effectiveness in removing pollutant dyes. GO nano-powder was synthesized using an improved version of Hummer's method and subsequently thermally reduced at various temperatures, including 125, 150, 175, and 200 °C, under vacuum conditions. In the X-ray diffraction spectra, an intense (001) diffraction peak was initially observed at 9.136° (2θ) for pristine GO. This peak gradually shifted towards higher angles as the reduction process took place and eventually disappeared when the GO was reduced at 200 °C. The intensity ratio of the D and G bands (ID/IG ratio) for GO nano-powder in the Raman spectra decreased from 0.94 to 0.76 due to the reduction process. The FTIR spectra of GO and reduced graphene oxide (rGO) also illustrated the reduction process. The bandgap of pristine GO significantly decreased from 2.31 to 0.73 eV, as determined by ultraviolet–visible (UV–Vis) diffuse reflectance spectrophotometry during the reduction process. The surface area and pore volume of both pristine GO and rGO-150 were determined using the BET (Brunauer-Emmett-Teller) and BJH (Barrett-Joyner-Halenda) methods. The results indicated an increase in the BET surface area from 6.61 to 7.86 m2/g and a corresponding enhancement in pore volume from 0.118 to 0.128 cc/g after reduction. The adsorption and photocatalytic degradation behavior of pristine GO and reduced graphene oxides (rGOs) were examined using methylene blue dye. The pristine GO demonstrated impressive adsorption capability, effectively removing the dye by 85.78 % within just 15 min and achieving nearly 97 % removal after 4 h. In contrast, the highest photocatalytic degradation of methylene blue, about 47.58 %, was attained for the rGO sample reduced at 150 °C under the illumination of visible light.

Integrated Ozonation Ni-NiO/Carbon/g-C3N4 Nanocomposite-Mediated Catalytic Decomposition of Organic Contaminants in Wastewater under Visible Light.

Developing a hybrid process for wastewater purification is of utmost importance to make conventional methods more efficient and faster. Herein, an effective visible light-active nickel-nickel oxide/carbon/graphitic carbon nitride (Ni-NiO/C/g-C3N4)-based nanocatalyst was developed. A hybrid process based on ozonation and Ni-NiO/C/g-C3N4 visible light photocatalysis was applied to decolourize the Congo red (CR), Alizarin Red S (ARS), and real dairy industry wastewater. The synthesized catalyst was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Χ-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectrophotometry (UV-Vis DRS). The factors affecting the catalytic process were evaluated, including contact time, solution pH, initial dye concentration, etc. The degradation rate of CR and ARS was compared between the photocatalysis, ozonation, and integrated photocatalytic ozonation (PC/O3) methods. The results showed 100% degradation of CR and ARS within 5 min and 40 min, respectively, by integrated PC/O3. The reusability of the modified catalyst was evaluated, and four successive regenerations were achieved. The modified Ni-NiO/C/g-C3N4 composite could be considered an effective, fast, and reusable catalyst in an integrated PC/O3 process for the complete decolourization of wastewater.

Synthesis and photocatalytic effects of TiO2-Ag on antibiotic-resistant bacteria

Titanium dioxide (TiO2) is a semiconductor metal oxide extensively studied due to its photocatalytic properties that can be applied in various areas. However, the catalytic performance of TiO2 is limited at the UV spectrum, and the silver doping to titanium dioxide (Ag-TiO2) can increase the catalytic performance for visible light. In this work, Ag-doped TiO2 nanoparticles were synthesized to evaluate photocatalytic activity against sensitive and methicillin-resistant Staphylococcus aureus frequently associated with skin infections. The sol-gel method followed by Ag doping was applied to NPs synthesis. NPs were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM), UV-vis diffuse reflectance spectrophotometry (DRS), Semi-quantitative energy dispersive spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy. FTIR and EDS results confirmed the doping of silver in TiO2. MEV analysis evidenced spherical nanoparticles between 8.5 - 25.6 nm. The TiO2 nanoparticles combined with silver improved the antimicrobial effect of TiO2 under visible light at 180 min, however, the greatest antimicrobial effect was observed under UV light at 120 min.

Non-Invasive Analyses of Italian “Ostrogothic” Jewellery: The Desana Treasure

The Desana treasure is a remarkable assemblage of items made of gold, silver, gemstones and glasses found in north-western Italy. Most scholars agree on the fact that the core of the treasure might have belonged to a single deposit resulted from a long period of selection, accumulation and use. The treasure testifies to the evolution of goldsmiths’ art in Ostrogothic Italy and represents an extraordinary material trace of the Italian elites of the 5th–6th centuries. The Desana treasure was investigated with non-invasive instrumental analytical techniques, namely optical microscopy, UV-visible diffuse reflectance spectrophotometry with optical fibres and X-ray fluorescence spectrometry in order to record the chemical features of gemstones, coloured glasses and precious metals employed to produce the items. As for the gemstones, besides identifying typologies, data suggested India as the source for a sapphire pendant and for most of the garnets, whereas the emeralds may belong to different sources, among which Pakistan, India and Egypt. The investigation revealed the colouring agents and compositional features of the glasses, and the composition of the gold alloys. The results of the investigation highlight that the raw materials used by Late Antique Italian goldsmiths did not differ significantly from other neighbouring European and Mediterranean regions, although the garnets show some differences if compared with coeval jewels recorded north of the Alps. The dataset produced in this work complements the stylistic approach for the study of these amazing traces of the past and deepens our knowledge on the role of the Italian “Ostrogothic” jewellery in the frame of the coeval Mediterranean, Central European and Northern Pontic metalwork traditions.

The contribution of archeometry in characterization of decorative materials from the site of Villa di Teodorico in Galeata (Italy)

Villa di Teodorico in Galeata (Forlì-Cesena, Emilia Romagna) is an important archeological site in the north of Italy occupied from sixth century BC to twelfth century AD. The most interesting results concern the Roman age, when a large villa was built, and the late antiquity, when the Ostrogothic king Theodoric decided to build in this area his palatium (early sixth century AD). The archeometric investigation was performed on Roman wall paintings fragments and on late antique glass sectilia fragments belonging to Palazzo di Teodorico by using a multi-technique approach that included micro-Raman spectroscopy, scanning electron microscopy with energy-dispersive spectroscopy, X-ray powder diffraction, UV–visible–NIR diffuse reflectance spectrophotometry with optic fibers and optical stereo-microscopy.. This analytical approach allowed the identification of all components, collecting molecular, elemental, microscopic, morphological and chromatic data. The characterization of samples supplied essential archeological, historical and technological information. The production techniques and the rich materials employed suggest the importance of the site in different periods. The evolution of the manufacturing technologies and the possible trade routes mainly during late antique period are witnessed by the change in the raw materials.Graphical abstract

Phytocompounds Recovered from the Waste of Cabernet Sauvignon (Vitis vinifera L.) Vinification: Cytotoxicity (in Normal and Stressful Conditions) and In Vitro Photoprotection Efficacy in a Sunscreen System

We investigated plausible reuse for the dermocosmetic industry of byproducts from the winemaking process of red grapes (Vitis vinifera L. cv. C. Sauvignon) through the evaluation of one extract (grape pomace extract, GPE) and two fractions (one chloroform, GPE-CHF; one ethyl acetate, GPE-EAF). The samples were characterized analytically by liquid chromatography (HPLC) using a NIH 3T3 fibroblast cell culture to verify a cytosafety profile in normal and stressful environment (presence of H2O2), and by using it in a sunscreen system to observe improvements in the in vitro efficacy by diffuse reflectance spectrophotometry with an integrating sphere. The HPLC results for GPE-EAF and GPE-CHF samples with the best profile of syringic and p-coumaric acids, quercetin, and trans-resveratrol were used in the further assays. GPE-EAF and GPE-CHF, both at 30.00 µg/mL, maintained the cell viability in the absence of H2O2 (normal condition). In the sequence, GPE-EAF and GPE-CHF were evaluated against the oxidative stressor H2O2 in NIH 3T3 cells. A sharp drop in viability was only observed for GPE-CHF, and cytotoxicity of GPE-EAF was considered absent even in a hostile environment. Since GPE-EAF previously developed the best results, its potential performance was investigated in a sunscreen system. The in vitro sun protection factor of the phytoderivative-free formulation was 9.0 + 2.5; by adding GPE-EAF at 10.0%, its efficacy was elevated to 15.0 + 2.5. Both samples suffered a negative effect after artificial ultraviolet exposition (500 W/m2); however, the presence of GPE-EAF improved the photostability of the sunscreen system.

Synthesis and Characterization of SCDs/TiO2 Composite

<p class="StyleE-JOURNALAbstrakKeywordsBold">Synthesis of sulphur-doped carbon nanodots immobilized on the TiO<sub>2</sub> surface (SCDs/TiO<sub>2</sub>) composite was carried out using the sol-gel method with SCDs and titanium tetraisopropoxide (TTIP) as precursors. SCDs were prepared from citric acid monohydrate, urea, and sodium disulphite using the microwave technique. SCDs/TiO<sub>2 </sub>was then visually observed under UV 365 nm and characterized by UV-Vis diffuse reflectance spectrophotometry (UV-Vis/DRS), Photoluminescence (PL) spectroscopy, Fourier transform infrared (FT-IR), and X-ray diffraction (XRD). The SCDs/TiO<sub>2</sub> composite product had a brown solid with a green luminescent under UV light. Furthermore, UV-Vis/DRS for variations in SCDs concentrations of 0.5%; 1.25%, and 2.5% showed Eg values of 2.33 eV, 2.14 eV, and 1.61 eV, respectively. The results showed that SCDs caused the maximum emission peak (λ<sub>Em</sub>) to redshift and also affected the intensity of PL TiO<sub>2</sub>. There was also a shift in the absorption peak towards the visible light region. Based on the results, the 0.5% SCDs/TiO<sub>2</sub> was the optimum concentration with the lowest intensity as an indication of separation of the (e<sup>-</sup>) and (h<sup>+</sup>) charge pairs, which greatly enhanced the photocatalytic efficiency.</p>

Phenolic compounds and color of labeled resin spurge honey and their correlations with pollen content

Our aim in this study was to outline phenolic and color characteristic that characterize the labeled unifloral resin spurge (Euphorbia resinifera) honey. With respect to phenolic composition, 17 phenolic compounds have been analyzed in the 29 honey samples. The proposed markers (syringic acid, ethyl gallate, m-coumaric acid and naringenin) might help to the enhancement of this honey type and thus, guarantee its commercial value. The color characterization by diffuse reflectance spectrophotometry revealed typical values of light amber honey (lightness ranged from 36 to 70 units, and chroma from 18 to 30 units). On the other hand, many correlations between the color attributes and phenolic acids, total phenolic compounds, caffeic acid, p- and m-coumaric acids and hesperidin have been demonstrated, also, correlation between phenols, color parameters and percentage of pollen of E. resinifera has been found. This study is one of the rare researches which have correlated the CIELAB color parameters with the individual phenolic acids and flavonoid compounds within the same unifloral honey.

Synthesis and characterization of 2D-carbonylated graphitic carbon nitride: A promising organic semiconductor for miniaturized sensing devices

Miniaturized chemical sensors are desirable for field analysis and screening trials aiming at point-of-care diagnostics. For this purpose, nanostructured materials, including those of the 2D family, are highly promising once they can add to sensing devices improved properties regarding sensitivity, the limit of detection, and portability. Here we report the synthesis, characterization, and application of 2D-carbonylated graphitic carbon nitride (c-g-C3N4) in the modification of screen-printed electrodes for photoelectrochemical analysis. Morphological and structural features of the material were studied through atomic force microscopy, scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction, Fourier transformed-infrared spectrophotometry, and X-ray photoelectron spectroscopy. The optical bandgap of the semiconductor was estimated using diffuse reflectance spectrophotometry. Glucose determination was performed as proof of concept using c-g-C3N4 as support for the immobilization of glucose oxidase and application of the photoelectrochemical sensor. The device presented a linear range from 0 to 5.00 mmol L−1 and a limit of detection of 0.43 mmol L−1. Our results indicate the suitability of employing c-g-C3N4 for designing photoelectrochemical sensors for detecting analytes of biological and medical interest.

Visible light responsive Cu-N/TiO2 nanoparticles for the photocatalytic degradation of bisphenol A.

Visible light active co-doped Cu-N/TiO2 photocatalyst was synthesized by the sol-gel method. The synthesized catalysts were characterized by X-ray diffraction (XRD), field-emission transmission electron microscope (FE-TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and UV-visible diffuse reflectance spectrophotometry (UV-vis DRS). The co-doping with Cu-N reduced the bandgap (∼2.83 eV) and extended the optical absorption range of TiO2 catalysts to the visible region. The incorporation of Cu and N on TiO2 lattice results in sub-conduction and valence band formation, which enhanced the photoactivity and electron-hole generation rate. The visible light activity of Cu-N/TiO2 was evaluated via photocatalytic degradation of bisphenol A (BPA) under blue LED illumination. The maximum BPA degradation of 42.7% was observed at 0.5 g L-1 catalyst dosage, initial pH of BPA solution = 8.2, and initial BPA concentration of 10 ppm. Further, a possible mechanism of photocatalytic degradation of BPA was also established.

The Use of UV-Visible Diffuse Reflectance Spectrophotometry for a Fast, Preliminary Authentication of Gemstones

The identification of gemstones is an important topic in the field of cultural heritage, given their enormous value. Particularly, the most important precious stones, namely diamond, emerald, ruby and sapphire, are frequently subjected to counterfeit by substitution with objects of lesser value with similar appearance, colour or shape. While a gemmologist is able to recognise a counterfeit in most instances, more generally, it is not easy to do this without resorting to instrumental methods. In this work, the use of UV-visible diffuse reflectance spectrophotometry with optic fibres (FORS) is proposed as a fast and easy method for the preliminary identification of gemstones, alternative to the classical methods used by gemmologists or to Raman spectroscopy, which is by far the instrumental method with the best diagnostic potential, but it cannot be used in situations of problematic geometric hindrance. The possibilities and the limitations given by the FORS technique are critically discussed together with the spectral features of the most important gemstones. Finally, the application of chemometric pattern recognition methods is described for the treatment of large sets of spectral data deriving from gemstones identification.

Mesoporous Nano-Sized BiFeVOx.y Phases for Removal of Organic Dyes from Wastewaters by Visible Light Photocatalytic Degradation.

With an increasing demand for industrial dyes in our daily lives, water conditions have become worse. Recently, the removal of such environmentally hazardous pollutants from wastewaters through photocatalytic degradation has been drawing increased attention. Three mesoporous nanophases of BiFeVOx.y as (Bi2FeIIIV1−yO5.5−y) visible light photocatalysts were synthesized in this study using ethylene glycol-citrate sol-gel synthesis combined with microwave- assisted calcination. X-ray diffraction (XRD), differential thermal analysis (DTA), FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS), nitrogen adsorption-desorption isotherms, and UV-Vis diffuse reflectance spectrophotometry (UV-Vis/DRS) were used to characterize the BiFeVOx.y photocatalysts. The visible light-induced photocatalytic activities of the BiFeVOx.y phases were evaluated by the degradation of methylene blue (MB) dye in aqueous solution at pH ~10.0. The results of this study show that the combination of doping strategy with the utilization of advanced synthesis methods plays an important role in improving the structure and surface properties of BiFeVOx.y phases, and thereby enhancing their adsorption and photocatalytic efficiencies. The synthesized mesoporous tetragonal γ-BiFeVOx.y nanophase has been proven to be a potential visible-light photocatalyst for the degradation of organic dyes.

Synthesis and control of the morphology of SnO2 nanoparticles via various concentrations of Tinospora cordifolia stem extract and reduction methods

SnO2 nanoparticles were synthesized utilizing Tinospora cordifolia stem extract. The effects of the concentration of the extract and the utilization of ultrasound irradiation on different chemical properties, mainly surface morphology, were studied. To determine the instrumental characteristics, X-ray diffraction, Fourier-Transform-Infra Red, scanning electron microscopy, and transmission electron microscope analyses were used. The optical properties of the material were studied using ultraviolet UV–visible diffuse reflectance spectrophotometry and photocatalytic activity tests on rhodamine B photodegradation. The results summarized the effect of T. cordifolia stem extract on the nucleation process during SnO2 crystallization, as a higher concentration leads to polymorphic forms with a greater particle size and an additional SnO phase. In addition, ultrasound-assisted reduction tended to produce a smaller particle size. The optical properties were found to be correlated with the particle size, as the higher particle size gave a smaller band gap energy and less photocatalytic activity for rhodamine B degradation.

Green hybrid photocatalyst containing cellulose and γ–Fe2O3–ZrO2 heterojunction for improved visible-light driven degradation of Congo red

In the present study, we aimed to investigate the photocatalytic behavior of a novel bimetal-biopolymer nanocomposite of cellulose/γ–Fe2O3–ZrO2 that was efficiently synthesized using a simple sol-gel method for photocatalytic applications. The photocatalysts were characterized by UV–visible diffuse reflectance spectrophotometry (DRS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer‒Emmett‒Teller (BET); the optical properties were determined by UV–visible spectrophotometry. Nano-ZrO2 significantly decreased the optical bandgap of nano-γ–Fe2O3 from 4.90 eV to 2.28 eV at the γ–Fe2O3:ZrO2 ratio of 1:1. Although the effect of nanocellulose on the energy bandgap of γ–Fe2O3–ZrO2 heterojunctions was insignificant, the impact of nanocellulose on the photocatalytic degradation of Congo red increased from 80.0% to 98.5% in 30 min, and the maximum degradation value was obtained at the nanocellulose:Fe2O3–ZrO2 ratio of 1:1. These results showed that the cellulose/γ–Fe2O3–ZrO2 nanocomposite demonstrated a higher photodegradation efficiency of Congo red under visible light than γ–Fe2O3–ZrO2, nano-γ–Fe2O3, and nano-ZrO2. Briefly, our results confirm that the cellulose/γ–Fe2O3–ZrO2 nanocomposite shows good photocatalytic activity toward the degradation of Congo red pollutants and can be a suitable candidate for various eco-friendly environmental applications.

Pristine and Nickel Doped Bismuth Vanadate Nanopowder For p-Nitrophenol Degradation Under UV Light Irradiation

The present work reports the degradation of p-Nitrophenol using pure and various concentration of BiVO4/Ni hybrid material synthesized by the precipitation method. The structural and morphological studies were performed using X-ray diffraction and scanning electronic microscopy coupled to energy dispersive X-ray spectroscopy. Through the calculation of the Kubelka–Munk function applied to diffuse reflectance spectrophotometry data, the hybrid material presented absorption edge of 2.5 to 2.87 eV. UV–Vis spectrophotometry experiments were performed in order to monitor the degradation of p-nitrophenol and the formation of secondary products. The application of pure and BiVO4/Ni-based photo catalyzer led to a decrease in total organic carbon after the degradation of p-Nitrophenol. Based on the results obtained in the study, pure and BiVO4/Ni (3%, 5% and 7%) has proved to be a promising material suitable for the removal of recalcitrant compounds in water treatment plants.

Photoelectrocatalytic degradation of caffeine using bismuth vanadate modified with reduced graphene oxide

Bismuth vanadate modified with reduced graphene oxide (BiVO4/rGO) was synthesized with the aim of applying this semiconductor material in advanced oxidative processes (AOPs) using the photoelectrocatalytic properties of the material for caffeine degradation. The semiconductor material was characterized by Scanning electronic microscopy, X-ray diffraction, Raman spectroscopy and UV–Vis Diffuse reflectance spectrophotometry. Photo-assisted linear sweep voltammetry experiments were carried out in order to evaluate the photocurrent generated in the processes. BiVO4/rGO was found to exhibit relatively better photoelectrocatalytic performance compared to bare BiVO4; this result confirms the fundamental role of the carbon-based material when it comes to photoanode construction. With regard to caffeine degradation by high performance liquid chromatography through the application of BiVO4/rGO photoanode, the signal used for monitoring the presence of the analyte exhibited a decrease of 100% of caffeine concentration from the original concentration, indicating the efficient removal of the compound from the sample.

Identification of aloe and other dyes by means of SERS and HPLC-DAD-MS in the embroidery of a 15th century English folded almanac

The folded almanac Western MS.8932 (Wellcome Collection, London), produced in England between 1387 and 1405, is a calendar with astrological tables and diagrams used by medical practitioners to harness astrological information relating to health. Apart from the great interest for its use in medicine, this object has a unique feature in its exquisite, unique embroidered binding that indicates a prestigious artefact. Considering the scarceness of information on such items, a diagnostic study on the materials used for the outstanding embroidery of MS.8932 is a unique occasion of having information on the methods of production of medieval embroideries. A diagnostic campaign has been carried out to identify the dyes used for this task and the colourants used for the illuminations, and to evaluate them with reference to their commercial value. Preliminary information on the dyes was yielded by means of UV–visible diffuse reflectance spectrophotometry with fibre optics (FORS) and spectrofluorimetry with fibre optics (FOMF). Then a final identification was yielded by micro-invasive analysis involving Surface Enhanced Raman Spectroscopy (SERS) and High Performance Liquid Chromatography-Diode Array Detector-Mass Spectrometry (HPLC-DAD-MS) [1]. Analysis on the micro samples (5–10 mm of very thin threads) taken from the embroidery revealed the presence of orchil for pink hues, indigo/madder double dyeing for purple hues, red safflower for salmon pink hues and indigo/weld double dyeing for green hues. Particularly remarkable was the additional identification of aloe in the purple threads, possibly used as mordant and/or as antibacterial agent, which evidence is the first ever recorded in such materials. This information is very important to understand the significance of the artefact and its historical-artistic location, and will allow to make comparison with similar artworks.

Multi‐technique characterization of glass mosaic tesserae from Villa di Teodorico in Galeata (Italy)

AbstractSeveral glass mosaic tesserae were found during the archeological excavations at the Villa di Teodorico in Galeata (Forlì‐Cesena, Emilia Romagna, Italy), dated to early sixth century AD. This work reports the results of an archeometrical investigation realized through a multi‐technique approach on 16 tesserae. The aims of the study were the determination of the glass composition, the characterization of coloring and opacifying agents, and the definition of the technological processes involved. The glass matrix and the dispersed crystallites were characterized in detail through micro‐Raman spectroscopy, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, and X‐ray powder diffraction analyses. Micro‐Raman spectroscopy was proven to be very effective in the analysis of complex objects, providing information on the structure and composition of the glass and on the nature of the opacifying agents and the crystalline colorants. UV–visible–NIR diffuse reflectance spectrophotometry with optic fibers was helpful to identify the metal ions used as chromophores. The different hues were obtained by means of dispersed ions as well as crystalline compounds and metal nanoparticles. A large variety of opacifying agents was detected. Results were compared with data of contemporary mosaics within the same geographical area.