SEM-EDX Techniques Research Articles

Biochar from Wood Chips and Corn Cobs for Adsorption of Thioflavin T and Erythrosine B.

Biochars from wood chips (WC) and corn cobs (CC) were prepared by slow pyrolysis and used for sorption separation of erythrosine B (EB) and thioflavin T (TT) in batch experiments. Biochar-based adsorbents were extensively characterized using FTIR, XRD, SEM-EDX, and XPS techniques. The kinetics studies revealed that adsorption on external surfaces was the rate-limiting step for the removal of TT on both WC and CC biochar, while intraparticle diffusion was the rate-limiting step for the adsorption of EB. Maximal experimental adsorption capacities Qmaxexp of TT reached 182 ± 5 (WC) and 45 ± 2 mg g−1 (CC), and EB 12.7 ± 0.9 (WC) and 1.5 ± 0.4 mg g−1 (CC), respectively, thereby indicating a higher affinity of biochars for TT. The adsorption mechanism was found to be associated with π-π interaction, hydrogen bonding, and pore filling. Application of the innovative dynamic approach based on fast-field-cycling NMR relaxometry indicates that variations in the retention of water-soluble dyes could be explained by distinct water dynamics in the porous structures of WC and CC. The obtained results suggest that studied biochars will be more effective in adsorbing of cationic than anionic dyes from contaminated effluents.

Methanol to Gasoline (MTG): Preparation, Characterization and Testing of HZSM-5 Zeolite-Based Catalysts to Be Used in a Fluidized Bed Reactor

The preparation of catalysts suitable for MTG processes in a fluidized bed reactor has been studied with emphasis on improving the textural, physico-chemical, morphological, structural and mechanical properties. A mixture of HZSM-5 zeolite (active material), boehmite or bentonite (binder) and alumina (inert filler) was used to prepare different catalysts. After preparation, characterization by physical adsorption of N2, XRF, XRD and SEM-EDX techniques was carried out. The screening of catalysts was performed in a fluidized bed reactor. The distribution of products was very similar in all cases, with the yield of light hydrocarbons always being higher than that of gasoline. Among the catalysts tested, the one containing boehmite as a binder (HZ_Boeh) was found as the most appropriate due to its high mechanical strength, high yield to aromatics and lower yield to durene.

Efficiency of iron modified Pyrus pyrifolia peels biochar as a novel adsorbent for methylene blue dye abatement from aqueous phase: equilibrium and kinetic studies

Herein, a magnetic biochar adsorbent based on Pyrus pyrifolia discarded peels impregnated with precursor FeCl3·6H2O was fabricated and probed as a low-cost adsorbent for toxic cationic dye methylene blue (MB). The textural characterization of Pyrus pyrifolia magnetic biochar (PMBC) obtained from BET analysis exhibited its mesoporous nature with SBET of 133.960 m2/g. The physicochemical characteristics of PMBC were elucidated using XRD, FTIR, SEM-EDX and TEM techniques. The impregnation of FeCl3 has a significant impact on the microstructure of Pyrus pyrifolia based biochar which resulted in enhancement in adsorption efficiency of PMBC. The sorption parameters adsorbent dosage, time, initial MB concentration, and pH were thoroughly elucidated using a batch methodology which were found to be 0.8 g/L, 40 min, 90 mg/L and 6, respectively. Temkin and pseudo-second-order rate equation respectively appropriated the equilibrium data than the rest of the models. The maximum adsorption capacity determined by the Langmuir model was found to be 967.80 mg/g. The adsorbent exhibited better regeneration up to 3 cycles validating its practical usage. The facile synthesis, economic, and environmentally benign characteristic of Pyrus pyrifolia magnetic biochar corroborated it as a highly efficient adsorbent to sequester MB from an aqueous phase.

Ultrasound-Promoted Sustainable Synthesis and Antimicrobial Evaluation of 2-Aryl Benzimidazoles Catalyzed by BPAE at Room Temperature

Background: Present-day chemists are more interested in developing and using green chemistry protocol for various organic transformations, which employ natural feedstock extracts, and solvent-free, and greener catalysts; they are well known for their non-hazardous nature and have replaced many organic and inorganic based catalysts. In literature, the reported homogenous catalytic approaches have been employed for various bioactive heterocycle syntheses, which follow the green chemistry principle established for various organic transformations catalyzed by WERSA, BFE, WEPPA, WEMFSA, WEMPA, and Eichhorniacrassipes. Among them, 2-aryl benzimidazole derivatives have emerged as prominent molecules with a wide variety of applications in biological and material science. Methods: The agro-waste sourced from the banana peel is utilized for the preparation of BPAE catalyst, which is employed for the synthesis of 2-aryl benzimidazole derivatives under ultrasound waves at room temperature. Results: Here, 2-Aryl benzimidazoles synthesized through the reaction of a substituted o-phenylene diamine with substituted benzoyl chloride catalyzed by BPAE under ultrasound waves at room temperature are described. Furthermore, catalyst BPAE is characterized by flame emission spectrometry, SEM-EDX, and XRD techniques. Conclusion: The present work established an eco-friendly, sustainable and novel approach for the synthesis of 2-aryl benzimidazoles using natural feedstock BPAE. The major merits of BPAE include its use as an agro-waste-derived catalyst. It is also highly abundant, inexpensive, yields faster reactions, has a simple workup, and does not require the use of column chromatography.

Biomimetic Growth of Hydroxyapatite on SiO2 Microspheres to Improve Its Biocompatibility and Gentamicin Loading Capacity.

The interest in multifunctional biomaterials to be implanted are also able to release drugs that reduce pain and inflammation or prevent a possible infection has increased. Bioactive materials such as silica (SiO2) containing surface silanol groups contribute to the nucleation and growth of hydroxyapatite (HAp) in a physiological environment. Regarding biocompatibility, the spherical shape of particles is the desirable one, since it does not cause mechanical damage to the cell membrane. In this work, the synthesis of SiO2 microspheres was performed by the modified Stöber method and they were used for the biomimetic growth of HAp on their surface. The effect of the type of surfactant (sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and polyethylene glycol (PEG)), and heat treatment on the morphology and size of SiO2 particles was investigated. Monodisperse, spherical-shaped SiO2 microparticles with an average particle size of 179 nm, were obtained when using PEG (SiO2-PEG). The biomimetic growth of HAp was performed on this sample to improve its biocompatibility and drug-loading capacity using gentamicin as a model drug. Biomimetic growth of HAp was confirmed by FTIR-ATR, SEM-EDX and TEM techniques. SiO2-PEG/HAp sample had a better biocompatibility in vitro and gentamicin loading capacity than SiO2-PEG sample.

Investigation on the potential sorbents — Aluminosilicate, microalga and grass hay as feed additives

In the present study, three natural materials — aluminosilicate, microalga Arthrospira (Spirulina) platensis and grass hay were examined in terms of sorption properties. Materials enriched with Cr(III), Mn(II) and Mg(II) ions were tested independently using two analytical techniques — ICP-OES and SEM-EDX. Preliminary sorption experiments were conducted with Cr(III) ions under following conditions: pH 5.0, 180 min, 300 mg/L of metal ions in the solution and 1 g/L of each sorbent. Maximum sorption capacity for aluminosilicate was 14.2 mg/g, for grass hay — 34.3 mg/g and for Spirulina platensis — 51.5 mg/g. ICP-OES and SEM-EDX techniques determined the enrichment of the sorbent. For all tested sorbents, the highest content of Cr, Mg and Mn was in the enriched Spirulina platensis (16.2 ± 3.25 g/kg; 6.98 ± 1.40 g/kg; 10.6 ± 2.12 g/kg, respectively), then grass hay (13.7 ± 2.74 g/kg; 4.59 ± 0.92 g/kg; 9.38 ± 1.88 g/kg, respectively) and finally aluminosilicate (8.69 ± 1.74 g/kg; 4.47 ± 0.89 g/kg; 4.03 ± 0.81 g/kg, respectively). The most even distribution of Cr, Mg and Mn after sorption was noted for aluminosilicate. Our results regarding sorption properties and those of scientific reports on the nutritional value of Spirulina platensis show that this biosorbent can be used as a potential feed additive.

New Nanoparticles of Fe3O4@SiO2 Functionalized Sulfonic Acid Magnetic Properties and Catalytic Investigation on the Multi-Component Preparation of Some Organic Compounds

Fe3O4@SiO2 functionalized sulfonic acid (FSSA) was prepared by a facile method in three steps and characterized by XRD, FT-IR, SEM-EDX, TGA, UV-Vis, and VSM techniques. The XRD pattern shows the characteristic peaks of the cubic structure of Fe3O4. The presence of sulfonic acid groups was confirmed by FT-IR analysis. FSSA shows reasonable magnetic parameters with good saturation magnetization (Ms = 22.61 memu/g). FSSA was used as a catalyst for the preparation of chromeno[4,3-d]pyrido[1,2-a]pyrimidin derivatives via the condensation of 4-hydroxycoumarin, aldehydes, and 2-aminopyridines under reflux in EtOH (50%) as well as US irradiation. The effect of solvent, temperature, and catalyst dosages on the product formation under reaction conditions was investigated. The effect of various Lewis and Bronsted acid catalysts was compared with FSSA and among different catalysts screened, FSSA was found to have the best efficiency. Next, FSSA was used for the effective and high yielding preparation of 14-aryl-14H-dibenzo[a,j]xanthene derivatives, N-((2-hydroxynaphthalen-1-yl)(aryl)methyl)acetamide derivatives, 2,4,5-triaryl-1H-imidazole derivatives, and 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carbonitrile derivatives. Simple procedure, good yields, and short reaction times, as well as catalyst recovery, are the key advantages of this work.

Development of a rapid efficient solid-phase microextraction: An overhead rotating flat surface sorbent based 3-D graphene oxide/ lanthanum nanoparticles @ Ni foam for separation and determination of sulfonamides in animal-based food products

In this study, an overhead rotating flat surface sorbent based solid-phase microextraction was developed as a rapid and efficient method for simultaneous separation and determination of sulfonamides in animal based-food products. 3D graphene oxide/ lanthanum nanoparticles @ Ni foam was introduced as a novel selective sorbent. SEM-EDX and FT-IR techniques were applied for characterization of the sorbent. At optimum conditions, the linear ranges of 0.4–700.0 (µg L-1), 0.3–900.0 (µg L-1), and 0.25–500 (µg L-1) and the enrichment factors of 606.8, 604.3, 608.9 were obtained for SDZ, SMX, and SMZ, respectively. The LOD (S/N = 3) of 0.14, 0.11, 0.08 (µg L-1) were achieved for SDZ, SMX, and SMZ, respectively. The intra-day and inter-day precision (%) (five days, n = 7) for the concentration of 100 µg L-1 were less than 4.3 and 3.8, respectively. The recoveries over 90.0 % revealed high capability of the method for utilization in complex matrixes.

Systematic production of biodiesel fuel from palm oil over porous K2O@CaO catalyst derived from waste chicken eggshell via RSM/kinetic/thermodynamic studies

Sustainable synthesis of biodiesel fuel or fatty acid methyl ester (FAME) was studied via transesterification of palm oil (PO) over green/low-cost heterogeneous alkali (waste chicken eggshell/WCE) catalyst. The porous K2O@CaO catalyst was effectively prepared via one-pot hydration-dehydration-incorporation process. The following reformations of catalyst properties were characterized by BET, XRD, SEM-EDX, TGA, FT-IR and CO2-TPD techniques. As obtained results, the as-modified catalysts with characteristic properties such as stronger basic site, higher basicity and surface area were successfully achieved when compared with pristine/commercial CaO, resulting in more facile upgrading of PO to FAME product. An integration between 2k factorial process with Box-Behnken model found that significant factors was in the order of catalyst loading amount > reaction time > reaction temperature. Meanwhile, the obtained optimal conditions were catalyst loading amount = 3 wt% of oil, molar ratio of methanol to oil = 15:1, reaction temperature = 80 °C and reaction temperature = 2 h, imparting a maximum FAME yield of 87.5%. For kinetic and thermodynamic studies of 10%KI/CaO catalyzed transesterification of PO, the important parameters such as Ea, A, ΔH, ΔS and ΔG were found to be 40.04 kJ/mol, 2.85 × 102 min−1, 37.24 kJ/mol, − 172.61 J/mol.K and 60.97 kJ/mol, respectively. The calcium glyceroxide was easily formed during reusability test, resulting in a significant reduction of FAME yield. Thus, regeneration-calcination process at 800 °C was applied to fully recover its properties and catalytic performance. This work provided the eco-friendly strategy for FAME production which could be possibly applied in practical process.

Hydrocracking of Octacosane and Cobalt Fischer–Tropsch Wax over Nonsulfided NiMo and Pt-Based Catalysts

The effect of activation environment (N2, H2 and H2S/H2) on the hydrocracking performance of a NiMo/Al catalyst was studied at 380 °C and 3.5 MPa using octacosane (C28). The catalyst physical structure and acidity were characterized by BET, XRD, SEM-EDX and FTIR techniques. The N2 activation generated more active nonsulfided NiMo/Al catalyst relative to the H2 or H2S activation (XC28, 70–80% versus 6–10%). For a comparison, a NiMo/Si-Al catalyst was also tested after normal H2 activation and showed higher activity at the same process conditions (XC28, 81–99%). The high activity of the NiMo/Al (N2 activation) and NiMo/Si-Al catalysts was mainly ascribed to a higher number of Brønsted acid sites (BAS) on the catalysts. The hydrocracking of cobalt wax using Pt/Si-Al and Pt/Al catalysts confirmed the superior activity of the Si-Al support. A double-peak product distribution occurred at C4–C6 and C10–C16 on all catalysts, which illustrates secondary hydrocracking and faster hydrocracking at the middle of the chain. The nonsulfided NiMo/Al and Pt/Al catalysts, and NiMo/Si-Al catalyst produced predominantly diesel (sel. 50–70%) and gasoline range (sel. > 50%) hydrocarbons, respectively, accompanied by some CH4 and light hydrocarbons C2–C4. On the other hand, the hydrocarbon distribution of the Pt/Si-Al varied with conditions (i.e., diesel sel. 87–90% below 290 °C or gasoline sel. 60–70% above 290 °C accompanied by little CH4) The dependence of the isomer/paraffin ratio on chain length was studied as well. The peak iso/paraffin value was observed at C10–C13 for the SiAl catalyst.

Natural zeolite modified with 4-(3-triethoxysilylpropyl) thiosemicarbazide as an effective adsorbent for Cu(II), Co(II) and Ni(II)

BackgroundNatural zeolite heulandite (ZH) has been functionalized with 4-(3-triethoxysilylpropyl)- thiosemicarbazide (TSC) to increase the adsorption capacity of Cu(II), Co(II), and Ni(II) ions. MethodsThe functionalization is confirmed by nitrogen adsorption/desorption (BET), XRD, 1H, 13C NMR, FT-IR, and SEM-EDX techniques. The thermal stability of the modified zeolite is investigated by the TGA-DSC method. The adsorption of Cu(II), Co(II), and Ni(II) ions with the modified zeolite (ZH-TSC) is studied in one- and multi-ionic aqueous solutions with pH = 5.0. Significant findingsThe functionalization is accompanied by the significant structural changes in the surface of the zeolite. Grafting of TSC onto the zeolite decreases specific surface area and specific volume of pores and micropores of the material, the zeolite surface becoming more uniform and less porous. The adsorption capacity of ZH-TSC is found to be 0.46 mmol/g (29.5 mg/g), 0.42 mmol/g (24.9 mg/g) and 0.28 mmol/g (16.6 mg/g) for Cu(II), Co(II) and Ni(II), respectively.The adsorption of heavy metal ions on the surface of the modified zeolite ZH-TSC is mainly contributed by the formation of chelate complexes due to the donor-acceptor interaction of metal ions with nitrogen and sulfur atoms of the thiosemicarbazide fragment. Localization of Ni, Co, Cu coincides with the position of the coordination centers. Modified zeolite ZH-TSC can be used in environmental science, engineering, or medicine as an effective adsorbent/entero(hemo) adsorbent of heavy or toxic metals.

Preparation of melon peel biochar/CoFe2O4 as a new adsorbent for the separation and preconcentration of Cu(II), Cd(II), and Pb(II) ions by solid-phase extraction in water and vegetable samples.

The present research describes the successful preparation of melon peel biochar modified with CoFe2O4 (MPBC/CoFe2O4) followed by its usage as a new sorbent to separate, preconcentrate, and determine the toxic heavy metal ions by magnetic solid-phase extraction. The metal ion desorption was performed by 0.1M HCl solution with a volume of 5.0mL. Flame atomic absorption spectrometry (FAAS) was utilized for detection of the analyte levels. SEM-EDX, TEM, XRD, and FTIR techniques were carried out to illuminate the structure of MPBC/CoFe2O4. The fundamental variables affecting the adsorption and elution efficiencies of the analyte ions including solution pH, MPBC/CoFe2O4 amount, type and concentration of eluent, adsorption and desorption equilibrium time, and sample volume were optimized. The detection limits were calculated as 0.41, 1.82, and 3.16µg L-1 for Cu2+, Cd2+, and Pb2+ ions, respectively, with the relative standard deviation of lower than 4.2%. There were no substantial interference effects on the analyte ion recovery due to the presence of foreign ions at high levels. Five minutes of contact time was adequate to attain the adsorption equilibrium. The adsorption capacity of MPBC/CoFe2O4 was obtained as 106.4, 65.4, and 188.7mgg-1 for Cu2+, Cd2+, and Pb2+ ions, respectively, by utilizing Langmuir isotherm model. The pseudo-second order model is favorable to identify the adsorption kinetics. The method was validated by spike/recovery test, and then, it was successfully implemented to determine the aforementioned analyte levels in sea and stream water, pepper, black cabbage, eggplant, and tomato samples.

Glucose-derived bio-fuel additive via ethanolysis catalyzed by zinc modified sulfonated carbon

The transformation of biomass derivative components such as glucose to levulinate esters via direct conversion in alcohol with acid catalyst has attracted great attention. In this study, the sulfonate urea-furfural carbon cryogel doped with zinc (UFCS-Zn) has been applied as an acid catalyst for the glucose ethanolysis reaction. Initially, the carbon cryogel was prepared via a mixing process of urea and furfural in an acidic medium followed by freeze-drying and calcination steps. Then, the urea-furfural carbon cryogel (UFC) was sulfonated before modification with zinc via impregnation of zinc (II) nitrate to provide the Bronsted and Lewis acid catalyst which is required for reaction conversion. The effects of reaction parameters on the ethanolysis of glucose have been conducted to determine the selected condition in obtaining high ethyl levulinate yield. The parameters studied include the glucose feed (0.2 to 0.5 g), catalyst loading (0.15 to 1.2 g), and reaction temperature (140 to 190 °C). The catalyst was characterized using TGA-DTG, FTIR, and SEM-EDX techniques to study the surface chemistry and thermal stability. The glucose ethanolysis reaction with UFCS-Zn catalyst has provided maximum ethyl levulinate yield of 27.4 mol% at selected condition of 180 °C, 6 h, 0.8 g (1:2) of catalyst and 0.4 g of glucose. Based on characterization of UFCS-Zn, the presence of sulfonate group and Zn element on the catalyst through the sulfonation and impregnation steps have been verified. This result has been confirmed through the detection of SO3H functional group and Zn-O bonding from the FTIR, and elements of S, O, and Zn from the EDX. High thermal stability of the UFCS-Zn (via TGA-DTG curves) allows the catalyst to assist the reaction at setting temperature without degradation in mass during the reaction. The UFCS-Zn catalyst has drafted its potential as catalyst for further conversion of biomass components.

Response surface methodology mediated process optimization of Celestine blue B uptake by novel custard apple seeds activated carbon/FeMoO4 nanocomposite

The present study deals with the evaluation of performance and efficacy of a novel nanocomposite based on custard apple seeds derived activated carbon (CAS-AC), prepared by microwave-assisted technique, and FeMoO4 nanoparticles (NPs) synthesized through green route for Celestine blue B (CB) removal from simulated wastewater. The physico-chemical characterization of the nanocomposite was achieved by means of FTIR, XRD, SEM-EDX, TEM and BET techniques. The operational factors such as contact time, initial CB concentration, nanocomposite dosage, and initial solution pH were optimized by Response Surface Methodology. The equilibrium data, modeled with various isotherm and kinetic models, conformed well to Freundlich model and pseudo-second order rate equation, respectively with both intraparticle and film diffusion controlling the overall adsorption process. The considerably higher Langmuir saturation capacity of the nanocomposite towards CB adsorption at 298 K (112 mg/g) than other previously reported adsorbents together with good recyclability depicts its superior adsorptive performance. The spontaneity, feasibility and endothermic nature of the CB removal process were established from the thermodynamic parameters. The hydrogen bonding and π–π interactions primarily governed the overall adsorption mechanism. The spent NC was regenerated using 0.1 mol/l HCl solution. The CAS-AC/FeMoO4 NC showed good reusability maintaining its adsorption efficiency of 86.25% up to fourth consecutive cycles. The results obtained from the present study reflected that the nanocomposite is a promising adsorbent for the liquid phase amputation of CB in effective and efficient manner.

Fabrication and characterization of mesoporous guar gum/NiWO4 nanocomposite for efficient adsorption of phloxine B and crystal violet from aqueous solution and evaluation of its antioxidant activity

Guar gum/nickel tungstate (GG/NiWO4) nanocomposite is prepared using simple and cost-effective sol-gel technique, while NiWO4 nanoparticles are formed by co-precipitation method. The nanocomposite is characterized by FTIR, XRD, BET, SEM-EDX and TEM techniques. The effectivity of GG/NiWO4 nanocomposite is investigated for the sequestration of phloxine B (PB) and crystal violet (CV) from wastewater. The effect of dose, agitation time, initial solution pH, and initial dyes concentration is appraised. The adsorption isotherm, kinetics and thermodynamic parameters are also studied. Langmuir isotherm and pseudo-second order models are best fitted to the equilibrium data. The thermodynamic parameters confirm that adsorption is spontaneous, exothermic and entropy-driven. An excellent desorption of PB and CV from the loaded adsorbent is acquired by utilizing either ethanol or acetone with a desorption ability in the range of 57.60%–91%. The antioxidant activities of synthesized nanocomposite are also studied.

H2 production from the hydrolytic dehydrogenation of methylamine-borane catalyzed by sulfonated reduced graphene oxide-aided synthesis of ruthenium nanoparticles

A new catalyst was prepared using sulfonated reduced graphene oxide support with a large surface area containing ruthenium nanoparticles (Ru@rGO-SO3H). The developed Ru@rGO-SO3H catalyst was used in the hydrogen production process from the hydrolytic dehydrogenation of methylamine-borane (MeAB). Sulfonated reduced graphene oxide and the developed catalyst were characterized by Raman and FT-IR spectroscopies, ICP-OES, XRD, XPS, TEM, TEM-EDX, SEM and SEM-EDX techniques. The average particle size of Ru nanoparticles, which were homogeneously distributed on the sulfonated reduced graphene oxide surface, was found as 2.2 ± 0.2 nm. After analyzing the effect of nanocatalyst and substrate concentrations on the catalytic reaction, reactions were realized at different temperatures, the efficiency of the Ru@rGO-SO3H nanocatalyst in initial turnover frequency (TOFinitial) and the activation parameters (Ea, ΔH# and ΔS#) were calculated. According to the data obtained, the TOFinitial value was calculated as 5300.86 h− 1 (88.35 min− 1). Ea, ΔH# and ΔS# values were also calculated as 53.83 kJ/mol, 50.73 kJ/mol and −51.55 J/mol.K, respectively. Finally, when the reusability performance results of the catalyst are evaluated, it is found that the catalyst is very stable and retains its initial effectiveness to a great extent (>95%) after the 5th reuse.

On the growth of copper oxide nanowires by thermal oxidation near the threshold temperature at atmospheric pressure

This study focuses on the growth of copper oxide nanowires networks (CuO NWs) close to the onset temperature, found to be 310 ℃. The NWs were obtained by thermal oxidation in air of polycrystalline copper foils on hot plate. The investigated oxide layers with the NWs network on their surface grown between 200 ℃ and 440 ℃, were characterized by: SEM-EDX, STEM-EDX, XRD, and micro-Raman techniques. The accurate determination of copper content in self-exfoliated oxide sheets is above the stoichiometric concentration. XRD reveals nano-crystallites of 20–40 nm, in Cu2O phase of thick oxide sheets located close to the oxide-substrate interface. Statistical data on the average length of the NWs versus annealing time indicates unexpected early saturation in between 10 and 40 min at 320–340 ℃. A semi-empirical model proofs quantitatively that the emerging delays of the NWs relative to the start of copper oxidation determine the plateau of the average length versus time. The excess concentration of copper found in the cuprous oxide layer is cautioned to accompany the early saturation effect having critical restrictions regarding the oxidation time and temperature. This study sustains the development of control and monitoring methods, applied to the growth of CuO NWs.

Au-doped mesoporous SiO2 scattering layer enhances light harvesting in quasi Solid-State dye-sensitized solar cells

This study investigates the morphological effect of different Au-doped SiO2 scattering layers on the performance of dye-sensitized solar cells (DSSCs). Particularly, the SiO2 sources were varied to yield different geometries, i.e., tetraethyl orthosilicate (TEOS) templated SiO2, Sidoarjo mud (LuSi) extracted SiO2, and commercial silica glass sphere. The microstructure, as well as physical, electronic, and optical properties of different Au-doped SiO2 particles, were characterized using SEM-EDX, TEM, BET, XRD, and various spectroscopy techniques. The photoelectrochemical performance of quasi-solid state DSSCs was indicated by current density–voltage (J-V) response, external quantum efficiency spectra, and the impedance response. The results indicate that the performance of TiO2-based DSSCs is enhanced quite significantly due to the improved photocurrent generation and fill factor. The short circuit current density is found up to 370% higher (and hence, the conversion efficiency) than the reference cell upon incorporating Au-doped crystalline SiO2 extracted from LuSi (Voc = 0.89 V, Jsc = 1.28 mA‧cm−2, FF = 0.65, and η = 0.75%). This substantial photocurrent enhancement stems from the combined effect of efficient light scattering by submicron SiO2 particles, surface plasmon resonance, and reduced interfacial recombination by SiO2 insulation. In addition, the optimum size of SiO2 particles is deduced as the results indicate the size-scattering dependency which controls the gain and loss of photocurrent due to the type of scattering.

The combined use of SEM-EDX, Raman, ATR-FTIR and visible reflectance techniques for the characterisation of Roman wall painting pigments from Monte d\u2019Oro area (Rome): an insight into red, yellow and pink shades

The aim of this work has been the identification of the painter’s materials employed in the wall decoration of some destroyed buildings dating approximately between the first century B.C. and the first century A.D. This research originates from a previously started joined archaeological and analytical investigation concerning a varied group of findings that resulted from a rescue excavation performed by Soprintendenza Archeologica in the area of Monte d’Oro in Rome. The focus of this study progression has been directed to a numerous selection of monochrome red, pink and yellow-pigmented fragments. The analyses were performed by means of scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX) combined with Raman and Fourier transform infrared (FTIR) spectroscopies; visible reflectance measurements have also been carried out and the relevance of this technique in such a kind of archaeological studies has been highlighted. Most attention has been given to the assessment of the performances of non-destructive techniques achieved by portable Raman, and visible reflectance instrumentation to test their diagnostic capabilities. In addition to the expected and well-known pigments such as cinnabar, red ochre, hematite for the reds and yellow ochre for the yellows, the study highlighted a diffuse use of mixed colours and in some cases the possible presence of overlapped painted layers and confirmed the presence of gildings. Among the mixtures of pigments, the most singular outcome concerns the pink fragments revealing the possible application of bone white, which seems to be rather uncommon as a pigment in Roman wall decorations.

Hydrolytic enzyme modified magnetic nanoparticles: An innovative and green microextraction system for inorganic species in food samples

In the presented study, the usability of hydrolytic enzyme immobilized magnetic nanoparticles as an extraction agent for the microextraction of metal ions from food samples was investigated. α-amylase modified magnetic carbon nanotubes (α-amylase-Fe3O4/MWCNTs) was used as an extraction agent for direct microextraction of trace arsenic from food sample phase into liquid phase medium prior to its ICP-MS determination. In extraction studies using hydrolytic enzymes, it is impossible to recover the free soluble enzyme after extraction without losing its activity. In our study, this problem was overcome by immobilizing the hydrolytic enzyme on magnetic support. In this way, α-amylase-Fe3O4/MWCNTs as an extraction agent with a reuse property of at least six times was used. α-amylase-Fe3O4/MWCNTs was characterized by FT-IR, XRD, SEM, SEM-EDX, VSM, TGA, and DTG techniques. Optimization of the presented method was performed using 1568 A rice flour certified reference material. Analytical parameters such as type of hydrolytic enzyme, pH and volume of the aqueous phase, extraction temperature and ultrasonic irridation time were optimized. The microextraction step was performed in ultrasonic water bath within only ∼15 min. Limit of detection (LOD), limit of quantification (LOQ) and relative standard deviation (RSD %) values for the developed method were found to be 14.3 μg kg−1, 47.3 μg kg−1 and 7.5%, respectively. The method was successfully applied to the analysis of arsenic contents of different rice and flour samples.