Scanning Electron Microscopy Mapping Research Articles

Preparation of Er3+, Ho3+, Yb3+-doped Bi2WO6 upconversion luminescent materials and their temperature sensing properties

A high-temperature solid-phase method was used to prepare codoped Bi2WO6 upconversion luminescent materials with different concentrations of Er3+, Ho3+, and Yb3+. The microstructure, upconversion luminescence and temperature sensing properties of the synthesized powders were analyzed. X-ray diffraction (XRD) patterns showed that the doping of Er3+, Ho3+, and Yb3+ did not affect the orthorhombic crystal structure of the Bi2WO6 matrix material. As the calcination temperature increased from 800 °C to 1000 °C for 3h, the average particle sizes of the 1% Er3+, 1% Ho3+, 1% Yb3+: Bi2WO6 samples decreased, and the luminescence weakened. Scanning electron microscopy (SEM) images showed that the morphology of the sample for 1% Er3+, 1% Ho3+, 1% Yb3+: Bi2WO6 with calcination at 800 °C was nearly spherical, with particle sizes ranging from 1 to 5 μm and some agglomeration. SEM mapping showed that the elements were more uniformly distributed on the surfaces of the sample particles, and energy-dispersive X-ray spectroscopy (EDS) analysis showed that each element was distributed with in the particles. Er3+, Ho3+, and Yb3+ codoping was used to regulate the Yb3+ doping concentration, and under 980 nm excitation, the strongest upconversion emission was obtained for the prepared 1% Er3+, 1% Ho3+, 1% Yb3+ samples. Compared with that for the Er3+, Yb3+-doped Bi2WO6 sample, the luminescence intensity of the characteristic emission peak of Er3+ at 525 nm for the Er3+, Ho3+, Yb3+-doped sample was weakened, while the luminescence of the characteristic emission peak of Ho3+ was enhanced; these results indicated that energy transfer from Er3+ to Ho3+ occurred. The intensities of the four emission peaks at 525 nm, 546 nm, 660 nm, and 756 nm in the 1% Er3+, 1% Ho3+, 1% Yb3+-doped Bi2WO6 sample increased with increasing excitation pump power from 45 mW to 233 mW. Based on the relationship between the excitation pump power and the emission intensity, all four luminescence peaks originated from two-photon absorption. The fluorescence intensity ratio versus temperature was fitted using three different nonthermally coupled energy level pairs in the range from 298 K to 573 K. The maximum absolute temperature sensitivity of 0.296 K-1 was obtained at 573 K for the Ho3+ nonthermally coupled energy level pair, and the maximum relative temperature sensitivity of 0.279 K-1 was obtained at 298 K. The temperature resolution for characterization using the above nonthermally coupled energy level pairs was calculated, with the temperature resolution δT yielding a minimum value of 0.03 K. The CIE color coordinates at different temperatures were calculated, and the color coordinates gradually moved from the green region to the red region.

RSM optimized chitosan based composite hydrogel for sustained drug delivery applications

Hybrid hydrogels with good biocompatibility have practical applications in the field of drug delivery. However, it remains challenging to formulate the hybrid hydrogels for sustained drug release by regulating their pore size and degradation rates. Herein, a hybrid chitosan-alginate hydrogel (superabsorbent) was synthesized using maleic acid as a cross-linker and acrylamide as a grafting agent. The composite hydrogel exhibited a good swelling percentage of 1246% (at pH 10), analysed using response surface methodology (RSM). The hybrid hydrogel system was hemocompatible as well as biocompatible and utilized for drug delivery applications. Pantoprazole sodium was taken as a model drug and it was loaded in the superabsorbent using the swelling diffusion method. The composite hydrogel showed excellent encapsulation efficiency for pantoprazole sodium (99.74%). The intermolecular interactions between hydrogel and drug were examined using different analytical techniques including XRD (X-Ray Diffraction), FTIR (Fourier transform infrared), SEM (Scanning electron microscope), thermal analysis and EDX (Energy dispersive X-ray) mapping. The swelling percentage of the drug loaded hydrogel under simulated gastrointestinal conditions was recorded as 917.80% (at stomach pH 1.2) and 756.95% (at intestinal pH 7.4) where protonation/deprotonation of the drug in the hydrogel matrix played an important role. In vitro drug release from the drug-loaded hydrogel was sustained up to 10 days and correlated with its swelling tendency, displaying higher release profiles at pH 1.2 (99.69%) than at pH 7.4 (72.16%). The pore volume of hydrogel was tuned varying the cross-linker amount during synthesis. BET (Brunauer-Emmett-Teller) results revealed that the pore volume of the hydrogel varied between 0.01775–0.01327 cm3/g for the cross-linker amount between 0.18–0.26 g, respectively. The impact of various factors including amount of cross-linker, pore volume, and drug loading percentage on drug release at pH 1.2 and 7.4 was studied statistically as well as experimentally and these factors significantly controlled the drug release percentage. The drug release from the hydrogel followed the Makoid-Banakar model with Fickian diffusion mechanism. The synthesized composite chitosan-alginate hydrogel could be a promising candidate for its utilization as a sustained drug delivery system.

Design of polyurethane composites obtained from industrial plastic wastes, pyrite and red mud

The purpose of this study consisted in the synthesis and characterization of composite materials based on polyurethane (PUR) rigid foam reinforced with two industrial wastes such as pyrite and red mud for the retention of mercury ions, Hg2+, ions from contaminated water and applications as paving stones in construction area. The diol used to create the urethane bond resulted from the depolymerization of poly(ethylene terephthalate) (PET) wastes in the presence of diethylene glycol (DEG). The resulted diol was characterized by gel permeation chromatography (GPC), registering a molecular weight, Mn = 420 g/mol. The hydroxyl index of the diol, IOH = 256.731 mgKOH/g was determined based on ASTM D4274-99. In this study, 6 types of PUR foams were obtained by reacting the diol with the polycondensation agent, 4,4′-methylene diphenyl diisocyanate (MDI) in the presence of different concentrations of filling agents. All specimens were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), EDX mapping, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and compression tests. The formation of urethane group was confirmed by FT-IR for all specimens. The porous structure of the PUR foams was evidenced by SEM, while (EDX) and EDX mapping were used to analyze the elemental composition of the composite materials and the uniform distribution of the filling agents within the cellular structure. TGA proved that both types of PUR foams increased their thermal resistance compared with blank samples. However, the specimens loaded with red mud exhibited increased thermal resistance as the concentration of red mud was increased compared with pyrite-based samples. The final residual mass registered for red mud was 24%, compared with pyrite-based samples that registered 21%. Unexpectedly, the DSC analysis indicated that Tg values decreased up to 47 °C as the pyrite concentration was increased compared with blank sample (57 °C), while the Tg values for red mud-based samples increased as the concentration of the red mud was increased up to 60 °C. Similar results were confirmed by the compression tests, this behavior being attributed to pyrite aggregate formation in PUR matrix and confirmed also by the density values for which a correlation between the filling agent concentration and density was not possible. In the case of red mud-based PUR foams the mechanical resistance decreased as the concentration of the filling agent was increased as expected.

Effects of extraction techniques on textile properties of William banana peduncle fibers

In this research work, the effect of extraction methods on the physical (morphology, density, length, apparent diameter, and color) and mechanical (tensile and bending KAWABATA) properties of the William banana peduncle fibers were examined. Among the methods used to carry out those tests, can be cited; the extraction tests using water retting (WR), dew retting (DR), and rolling by mechanical extraction (ME). The mechanical tests were carried out using TEXTECHNO Vibromat ME (measurement of the vibration frequency of the fiber), tensile test (MTS 20/M), and a Bending KAWABATA KES-FB2-SH test. To analyze the microstructure of the longitudinal plane of William banana peduncle, Scanning Electron Microscopy (SEM) mapping was used. The results showed that, water retting, gave a high yield (42.55%) compared to fibers extracted by rolling (23.40%). The different methods of extraction by retting lead to a reduction of about 35% in the apparent diameter of the fibers compared to the fibers obtained mechanically. When studying the colors of the surfaces of the fiber, the results presented the fact that the fibers extracted by rolling (ME) were darker than those retted in water or dew (WR and DR). However, the retted fibers were redder and yellower compared to the fibers passed through a rolling mill. SEM mapping was a result of strips of flat fiber bundles, followed by the brittle fracture surface regardless of the extraction method used. water retted fibres are longer than those extracted by rolling. There was a high uniformity index (UI) value for WR (70. 89%), which showed that these fiber bundles were more uniform in length compared to the two other methods (66.4% for DR and 64.28% for ME). The density of the William banana peduncle was not very sensitive to the extraction method. Significant differences were revealed for the specific breaking strength, initial modulus, and elongation at break depending on the extraction method. The Kawabata bending test showed the fact that fibers extracted by rolling were stiffer (1.63 mNmm2/tex2) compared to retting method fibers (0.51 mNmm2/tex2 for WR and 0.73 mNmm2/tex2 for DR). There is a possibility of using William banana fiber for textile applications in view of the tensile and bending properties obtained.

TiO2/porous carbon as a new nanocomposite and catalyst for the preparation of 4H-pyrimido[2,1-b]benzimidazoles.

A nano TiO2/porous carbon nanocomposite (TiO2/PCN) was designed by the pyrolysis of peanut shells as bio waste with nano titanium dioxide. In the presented nanocomposite, titanium dioxide is properly placed in the positions and pores of the porous carbon, so that it acts as an optimal catalyst in the nanocomposite structure. The structure of TiO2/PCN was studied by various analyses such as Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray Spectroscopy (EDX), scanning electron microscopy (SEM), SEM coupled EDX (SEM mapping), transmission electron microscopy (TEM), X-ray fluorescence (XRF) and BET. TiO2/PCN was successfully tested as a nano catalyst for the preparation of some 4H-pyrimido[2,1-b]benzimidazoles in high yields (90-97%) and short reaction times (45-80 min).

Water resistance of fly ash phosphoric acid-based geopolymer

Phosphoric acid (PA)-based geopolymers are different from alkali-activated materials. The PA-based geopolymers have good mechanical properties, but the related research is still less, especially the research concerning the durability of geopolymers has received less attention, which has brought some trouble to the engineering application. In this article, to further study the water resistance of PA-based geopolymer prepared using fly ash, the unconfined compressive strength tests were conducted to evaluate the water resistance. Meantime, the Scanning Electron Microscopy (SEM), SEM-EDS, SEM mapping, Mercury Intrusion Porosimetry, X-ray Diffraction, and Infrared Spectroscopy tests were used to reveal the mechanism of strength weakening of the geopolymers after soaking. The results show that the water resistance of the geopolymer first increased and then decreased with the increasing PA concentration. When the PA concentration was 50%, the geopolymer with the optimal PA concentration gave the best water resistance. The compressive strength was decreased significantly after soaking, and the strength first decreased rapidly and then reduced slowly with the soaking time increasing. At 7 days of soaking, the strength decreased rapidly with a decrease of 30–50%. After 7 days of soaking, the strength decreased slightly. After soaking, the at 180 days of soaking, the geopolymer specimens cracked except for the geopolymer with the optimal PA concentration. If the water stability of the acid-based geopolymer is not improved, it is difficult to meet the requirement of engineering application. The microscopic analysis shows that quartz and mullite did not participate in the polymerization, and the crystalline compounds formed in the geopolymer matrix, such as CaPO3(OH)·2H2O, CaHPO4, AlPO4, and CaPO3·OH, basically did not change after soaking, but some calcium-containing crystalline compounds leached after recrystallization after soaking in water, and the Si–O–P unit in the amorphous gel in the geopolymer hydrolyzed after soaking, also leading to the decrease the geopolymer strength.

Fe3O4@CS‐Ni: An efficient and recyclable magnetic nanocatalyst for α‐alkylation of ketones with benzyl alcohols by borrowing hydrogen methodology

This paper reports a heterogeneous magnetic impressive nickel catalyst in which Fe3O4 nanoparticles have been coated with chitosan and decorated with nickel nanoparticles (Fe3O4@CS‐Ni). This catalyst has been used for direct α‐alkylation of aryl ketones with substituted benzyl alcohols through borrowing hydrogen and dehydrogenation mechanism that affords the corresponding α‐benzyl ketones, with good to excellent yield. The core‐shell morphology has been confirmed with different analysis techniques such as Fourier‐transform infrared (FT‐IR), X‐ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), SEM mapping, energy‐dispersive X‐ray (EDX), inductively coupled plasma (ICP), and thermogravimetric analysis (TGA). Moreover, the catalyst could be recovered from the reaction mixture by using an external magnetic field and reused for six successive cycles without a considerable decrease in catalytic activity.

Lunar Terrestrial Analog Experiment on the Spectral Interpretations of Rocks Observed by the Yutu-2 Rover

A visible and near-infrared imaging spectrometer (VNIS) loaded by the Chang’e-4 rover is the primary method for detecting the mineral composition of the lunar surface in the landing region. However, different data processing methods yield inconsistent mineral modes in measured lunar soil and rocks. To better constrain the mineral modes of the soil and rocks measured by Chang’e-4 VNIS, a noritic-gabbroic rock with a mineral composition similar to that of the lunar highland rocks is measured by scanning electron microscopy (SEM), the spare flight model of Chang’e-4 VNIS and TerraSpec-4 of ASD. Backscattered electron and energy dispersive spectrometry show that olivine, pyroxene, and plagioclase modal mineral abundances are 12.9, 35.0, and 52.2%, respectively. The estimated results of the spectrum by the Hapke radiative transfer model are 7.5, 39.3, and 53.2% for olivine, pyroxene, and plagioclase, respectively, which is consistent with to those of SEM mapping within error. In contrast, the estimated results of the modified Gaussian model are 29 and 71% for olivine and pyroxene, respectively, indicating the absence of plagioclase. Based on our implemented Hapke model, we decode the data of the two rocks detected by the rover on the 3rd and 26th lunar days of mission operations. The obtained results suggest that both rocks are norite or gabbro with noticeable differences. The first rock, with more olivine and pyroxene, may have been excavated from the Finsen crater. The second rock, with more plagioclase, may have been ejected from the southwestern edge of the Von Kármán crater, indicating the initial lunar crust.

New way to obtain the poly(L-lactide-co-D,L-lactide) blend filled with nanohydroxyapatite as biomaterial for 3D-printed bone-reconstruction implants

A novel, bone-reconstruction dedicated polymeric-nanohydroxyapatite material has been prepared for 3D-printed implant. The composites of poly(L-lactide-co-D,L-lactide) (PLDLLA) and nanosized hydroxyapatite were prepared by a co-rotating twin-screw extrusion. Structural properties of the filler and polymeric blends were characterized by XRD (X-ray Powder Diffraction), SEM (Scanning Electron Microscopy), and EDS mapping (energy dispersive spectroscopy), FT-IR (Fourier-transformed infrared spectroscopy), and NMR (Nuclear Magnetic Resonance) technics. Molar masses of the composites at various preparation steps were also investigated. The structural studies and thermogravimetric analysis proved a successful preparation of the nanohydroxyapatite and its nanocomposites. Mechanical results in conjunction with density values, reported as close to human bone, evidenced usability of this novel material for internal bone fixation implant. Contact angle analysis showed favored growth of tissue on the biocomposite containing 10 wt% of the filler. The PLDLLA-based composite can be an excellent candidate for bone reconstruction implants due to their superior mechanical properties, bioactivity, and complete resorbability.

Investigating phosphate-adsorption behaviour on a real ferrallitic-ferritic soil using a pluralistic approach under non-controlled conditions

Context Ferralsols, which cover approximately 6% of the Earth’s continental surface, have unique phosphorus (P) retention properties.Aims The research investigates P adsorption properties under non-controlled conditions on lateritic soil samples, combining different methodological approaches.Methods Ferralsol samples were analysed using (1) adsorption kinetics and capacities (wet chemical experiment methods), (2) scanning electron microscopy (SEM) and transmission electron microscopy and (3) attenuated transmission reflectance-Fourier transform infrared spectroscopy (ATR-FTIR).Key results Wet chemical experiments accord with previous studies on lateritic soils where chemisorption mechanisms govern P adsorption. Further, P adsorption appears to affect soil particles’ structural stability and release of iron (Fe) species in solution. SEM mapping confirmed the location of P compounds in Fe-rich areas. ATR-FTIR identified two inner-sphere complexes: monodentate (FeO)PO2(OH) and bidentate (FeO)2PO(OH) at wavenumber positions 958±5, 1042±5 and 1095±8cm−1; and 930±5, 983±10, 1005±5 and 1122±9cm−1, respectively. Also, a band centred at 1030±4cm−1 suggested evidence of ternary complexes for P concentrations above 500mgP/L. Combined methods suggested the potential involvement of redox mechanisms and other ionic species in the formation and types of phosphate surface complexes.Conclusions Our approach builds on previous work in this field by showing evidence of complex ionic interactions governing P retention on lateritic soils. Novel insights are evidence of fluctuations in physical and chemical factors with phosphate adsorption and suggestion of inner-sphere and ternary surface complexation mechanisms.Implications Given the wide global distribution of lateritic Ferralsols, our findings have important implications for key emerging challenges relating to P cycling for crop production and environmental impact.

In-situ SEM cyclic nanoindentation of pre-sintered and sintered zirconia materials

Efficient diamond machining of zirconia requires a comprehensive understanding of repetitive diamond indentation mechanics. This paper reports on in-situ cyclic nanoindentations of pre-sintered and sintered zirconia materials performed inside a scanning electron microscope (SEM). In-situ SEM imaging of cyclic indentation processes and high-magnification SEM mapping of indentation imprints were conducted. The elastic and plastic behaviors of pre-sintered and sintered zirconia materials were investigated as a function of the cyclic nanoindentation number using the Sakai and Sakai-Nowak models. For pre-sintered zirconia, cyclic nanoindentation induced quasi-plastic deformation, causing localized agglomeration of zirconia crystals with microcracks and large cracking along the indentation edge. Severely compressed, fragmented, and pulverized zirconia crystals and smeared surfaces were also observed. For sintered zirconia, shear bands dominated quasi-plastic deformation with the formation of edge pile-ups and localized microfractures occurred at indentation apex and diagonals. All elastic and plastic behaviors for pre-sintered and sintered zirconia materials revealed significantly microstructure-dependent. Pre-sintered zirconia yielded significantly lower contact hardness, Young's moduli, resistance to plasticity, elastic deformation components, and resistance to machining-induced cracking, and higher elastic and plastic displacements than sintered state. Meanwhile, all the behaviors for the two materials were independent from the cyclic nanoindentation number. A model was proposed for cyclic nanoindentation mechanics, revealing their cyclic indentation-induced microstructural changes in the two zirconia materials. This study advances the fundamental understanding of nanoindentation mechanics of zirconia materials.

Fabrication and characterization of polystyrene/Fe-MOF composite beads for iodine uptake

The effective uptake of radioactive contaminants such as radioiodine, radioactive iodine, is considered crucial to reliable and nuclear energy production and nuclear medicine investigations. Metal-organic frameworks (MOFs)-based polymer composites are designed for sorption and separation of various pollutions. In this study, we report Fe(III) MOF-loaded polystyrene (PS) beads, PS/x%Fe-MOF x = 10, 30, 50, fabricated by a two-step method consisting of synthesis Fe-MOF and loading this material into PS matrix by the phase inversion method. The obtained materials were studied by various techniques, including FTIR (Fourier-transform infrared), XRD (X-ray diffraction), SEM (scanning electron microscope), and EDS (energy-dispersive X-ray spectroscopy) mapping. Based on the SEM images, the PS/x%Fe-MOF and PS beads have the same morphology. The incorporating of Fe-MOF particles into the PS matrix increases the porosity of the pure PS (10 m2 g−1) to 29 m2 g−1 for the PS/50 %Fe-MOF. The iodine adsorption studies were conducted using UV–vis spectroscopy. The as-prepared composite beads showed higher iodine adsorption capacities (19–123 mg g−1) than the pure PS beads (10 mg g−1) at ambient conditions. The kinetics of capturing iodine onto the PS and PS/x%Fe-MOF was defined by the pseudo-second-order (PSO) model. The results confirmed that these PS/30 %Fe-MOF composite has proper potential for iodine adsorption and could be used in a water treatment field.

Polycaprolactone/ZIF-8 nanocomposites fabricated for oil sorption and antibacterial applications

Hydrophobic sponges were fabricated of zeolitic imidazolate framework-8 (ZIF-8) and polycaprolactone (PCL) nanocomposites, PCL/x%ZIF-8 (x = 10, 30, and 50), through the sugar template strategy. The as-prepared nanocomposites were investigated by FTIR (Fourier-transform infrared), XRD (X-ray diffraction), SEM (scanning electron microscope), and EDS (energy-dispersive X-ray spectroscopy) mapping techniques. The obtained results demonstrated the successful incorporation of ZIF-8 into the PCL matrix. The sponge-like structure was confirmed by SEM images. The mass ratio effects of ZIF-8 and PCL on the oil sorption efficiency and antibacterial activity were studied. The nanocomposites exhibited suitable efficiency for adsorbing various oils, including olive oil, sunflower oil, and motor oil. Additionally, the sorbents can be recovered and reused easily. The results from oil adsorption investigations exhibited that the PCL/50%ZIF-8 has promising efficiency as an oil sorbent (12.1 g g−1). Also, the PCL/x%ZIF-8 composites (PCL/30%ZIF-8 and PCL/50%ZIF-8) resulted in a lethal effect on E. coli cells, suggesting their potential applicationas novel antibacterial materials for drinkingwater disinfection.

Nanocomposite of cellulose and magnetite-magnesia as catalyst for biodiesel from coconut oil

In this work, a heterogeneous catalyst was developed using MgO-Fe3O4 composite and cellulose biopolymer as support catalyst in the synthesis of biodiesel for transesterification reaction from coconut oil. The nanocomposite catalyst was analyzed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscopy-mapping (SEM- Mapping), and transmission electron microscope (TEM) to observe the structure, elemental composition and surface morphology. The parameters of reaction time and catalyst loading were studied to optimize the biodiesel yield. The maximum yields were obtained at 120 minutes and 2 wt.% having the yield of 89.93 %. This result shows high biodiesel yield in short reaction time. The biodiesels products have physical properties close to ASTM standards, with a density of 0.885 g/cm3 and acid number of 0.442 mg KOH/g. The biodiesel was tested using the gas chromatography (GC) pertained the greatest abundance at the retention time of 8.817 minutes which indicating that methyl dodecanoic (lauric methyl ester) have area 39.68 %. The cellulose biopolymer combined with MgO-Fe3O4 composite as green catalyst for heterogeneous catalysts which is promising in biodiesel production.

Zeolitic imidazolate frameworks/polyacrylonitile composites for oil sorption and antibacterial applications

Fabricated nanocomposites from polymers that have unique properties, including suitable porosity, flexibility, and biocompatibility are considered promising compounds for industrial (catalysis, sorption, and sensing) and biological (tissue engineering, drug delivery, and wound healing) applications. The new sponges of polyacrylonitrile (PAN) and the Zn(II) zeolitic imidazolate frameworks (ZIF-8), with different mass ratios, PAN/x%ZIF-8 (x = 10, 30, 50), were fabricated using the sugar template method. The as-fabricated composites were characterized via FTIR (Fourier-transform infrared), PXRD (powder X-ray diffraction), SEM (scanning electron microscope), and EDS (energy-dispersive X-ray spectroscopy) mapping. The FT-IR and PXRD results proved that the ZIF-8 nanoparticles were successfully incorporated into the PAN matrix. SEM and EDS-mapping images showed that ZIF-8 was dispersed and coated by PAN. The hydrophobicity nature of the as-fabricated sponges was confirmed by assessing the water contact angles (WCA) analysis. The PAN/50%ZIF-8 composite displayed proper hydrophobicity with a WCA of 136.2o. Our results from oil sorption studies demonstrated that PAN/x%ZIF-8 sponges had more appropriate efficiency for wastewater treatment than pure PAN. The PAN/50%ZIF-8 sponge composite showed the highest oil sorption capacities of 16.12, 17.8, and 23.8 g g−1 for sunflower oil, olive oil, and motor oil, respectively. In addition, the oil sorption kinetic investigation exhibited the as-fabricated sorbents followed the pseudo-second-order kinetics model. The antibacterial experiments revealed that PAN/50%ZIF-8 and PAN/30%ZIF-8 composites had significant antibacterial activity against E. coli (5.9 and 5.4 log10 CFU reduction, respectively). Thus, these new composites may be promising candidates for developing self-cleaning materials due to their strong hydrophobicity and antibacterial activity.

Synthesis of nanocomposites cellulose-Fe3O4/ZnO as novel green catalyst for biodiesel production from coconut oil

Cellulose-Fe3O4/ZnO nanocomposites have been successfully synthesized. This process was supported by characterization using Fourier Transform InfraRed (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Scanning Electron Microscopy-Mapping (SEM-Mapping) instruments. The successfully synthesized-nanocomposites then were tested for a catalytic activity in the transesterification reaction to form biodiesel. The results of the biodiesel production were characterized using Gas Chromatography - Mass Spectroscopy (GC-MS). The highest conversion of coconut oil into biodiesel was 90.6%, with a catalyst amount of 0.6% wt and a 120 minutes reaction time. The biodiesel production using GC-MS shows that the most formed-methyl esters are dodecanoic acid methyl esters (lauric acid methyl esters). The use of cellulose as a catalyst support by combining Fe3O4/ZnO composites is very promising to be a green catalyst in the reaction of biodiesel production.

Augmentation of Photocatalytic Degradation of Oxytetracycline by Cu-CdS and Deciphering the Contribution of Reactive Oxygen Species.

Production of Copper (Cu) modified Cadmium sulfide (CdS) nanomaterial, named as Cu-CdS, was successfully synthesized through hydrothermal and photo deposition method to degrade oxytetracycline (OTC) antibiotics in aqueous solution. Uniform surface loading of copper was observed on CdS using Scanning Electron Microscopy-mapping (SEM-mapping). The Cu induced improvement in the visible light absorption was observed using UV-vis absorption spectrum. Thus, this material can exhibit excellent oxytetracycline (OTC) degradation by photocatalysis. The best OTC degradation efficiency of 90% was be achieved under the optimal concentration of 4% Cu-CdS, with 0.1 g L-1 dosage (pH 5) under UV irradiation. 0.167 mg L-1 min-1 was observed as the reaction kL-H on the peripheral of the catalyst. In addition, OTC can also be degraded under visible light with removal efficiency approximately 90%. Moreover, the contribution of main reactive oxygen species (ROS), including hydroxyl radicals, superoxide radical and holes, is evaluated as 18%, 43% and 29%.

Comparison of Orientation Mapping in SEM and TEM.

Multiple experimental configurations for performing nanoscale orientation mapping are compared to determine their fidelity to the true microstructure of a sample. Transmission Kikuchi diffraction (TKD) experiments in a scanning electron microscope (SEM) and nanobeam diffraction (NBD) experiments in a transmission electron microscope (TEM) were performed on thin electrodeposited hard Au films with two different microstructures. The Au samples either had a grain size that is >50 or <20 nm. The same regions of the samples were measured with TKD apparatuses at 30 kV in an SEM with detectors in the horizontal and vertical configurations and in the TEM at 300 kV. Under the proper conditions, we demonstrate that all three configurations can produce data of equivalent quality. Each method has strengths and challenges associated with its application and representation of the true microstructure. The conditions needed to obtain high-quality data for each acquisition method and the challenges associated with each are discussed.

Reverse leaching of magnesium from ferronickel slag using alkali solvent NaOH

A research based on magnesium extraction of ferronickel slag waste processed by reverse leaching using sodium hydroxide (NaOH) solutions has been carried out. The ferronickel slag has the main compositions of magnesium silicate and iron silicate. The early procedure of the research was the preparation of ferronickel slag grinding using a ball mill until it gets a size of –200 mesh. Secondly, the calcination of ferronickel slags to remove crystal water and increase the size of the porosity so that it would facilitate the leaching process. The next procedure was reverse leaching using sodium hydroxide (NaOH) to dissolve silica. By dissolving the silica, it was expected that the contents of elements such as magnesium and iron would increase in the residue. The variations in this ferronickel slag leaching research were leaching time, solvent concentration and leaching temperature. The reverse leaching of ferronickel slag was carried out with a time variation of 15 to 240 minutes, the temperature of 30 °C, 70 °C, and 100 °C and NaOH concentrations are 9 M, 10 M, and 11 M. The XRD (X-ray diffraction) analysis, (XRF X-ray fluorescence) analysis, SEM (Scanning Electron Microscope) analysis, and ICP-OES (Inductively Coupled Plasma) analysis were used to observe the initial characteristics of the ferronickel slag and the results after the leaching process. The characterization result towards ferronickel slag samples by XRD analysis shows that the compositions of the dominant compounds are forsterite (Mg 2 SiO 4 ), enstatite (MgSiO 3 ) and fayalite (Fe 2 SiO 4 ). Moreover, the result is also supported by XRF analysis and SEM mapping analysis. The quantitative analysis of XRF shows that ferronickel slag contains 45.69 % of SiO 2 , 29.32 % of MgO and 16.5 % of Fe 2 O 3 . The results of the SEM mapping analysis show that Mg, Si, Fe and O bond together that indicates the presence of magnesium silicate and iron silicate. The highest percentage of magnesium extraction is 73.10 % under experimental temperature conditions of 100 °C for 240 minutes, 10 M of solvent concentration and 300 rpm of stirring speed. Increasing percentage of magnesium extraction is caused by the dissolution of silica in the leaching process. The dissolution of silica is proved by the existence of magnesium hydroxide and iron(II) hydroxide in the residue that is shown by the XRD analysis. It resulted in the MgO content in the residue increase significantly to 42.8 % as shown by the XRF analysis. Moreover, the SEM mapping analysis shows that Mg and O bond together that indicated the presence of MgO. It also can be determined that MgO is dominant

Low temperature design of titanium dioxide anatase materials decorated with cyanuric acid for formic acid photodegradation

The influence of cyanuric acid (CA) on the structural, textural, electronic, morphological properties and the photocatalytic activity of titanium dioxide materials (TNCA) were herein evaluated. TNCAs samples were prepared through the sol gel method. The novelty of this work that cyanuric acid; the so far most recalcitrant molecule, is used here as reservoir of nitrogen. The synthesis of TNCAs nanomaterials are performed at low temperature in presence of quaternary ammonium as co-catalyst for anatase growth. Samples were characterized by means of nitrogen adsorption-desorption isotherms at 77 K, X-ray diffraction (XRD), Infrared (ATR), Raman, diffuse reflectance ultraviolet-visible, photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic activities of TNCAs and their free counterpart nanomaterials were then evaluated in the photocatalytic degradation of formic acid (FA) as model molecule under UV.X-ray and Raman show success of anatase phase formation at low temperature without any post-calcination. IR-ATR analysis confirms CA grafting onto TiO2 identified by formation of vibration band between Ti and triazine. SEM mapping shows that C, O, Ti, and N are homogeneously distributed in the nanomaterial. Nitrogen adsorption-desorption measurements at 77 K show developed textural properties; the heat of N2 adsorption seems to be affected by CA loading. PL and UV-visible spectroscopies show simultaneously (i) electron trapping by the oxygen vacancy identified by Raman spectroscopy by redshift of Eg1 mode and (ii) the hole is confined by nitrogen. Therefore, the excited electron can move from TiO2 VB to the new sublevels initiated by the introduction of nitrogen which results in quenching of the photoluminescence intensity. The photocatalytic activity of the various TNCAs nanomaterials increases versus CA loading. The highest kLH of TNCA2 (5 wt%) could be explained by short migration time conjugated with lower bulk recombination of the photogenerated electron hole.