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Influence of pretreatment on surface interaction between Cu and anatase-TiO2 in the simultaneous photoremediation of nitrate and oxalic acid
摘要： Copper-promoted anatase-type TiO2 photocatalysts (2.5 wt% Cu) were prepared by wet impregnation onto TiO2 which was pre-calcined at 600°C and the other not subjected to any thermal pre-treatment. In the latter case, the material was inactive for the photo-reduction of nitrate whereas 600°C pre-calcined TiO2 yielded a material which was active for the same reaction. The surface properties of the materials were determined by BET Surface area, SEM TEM, XRD, XPS, TPR, UV-Visible diffuse reflectance, DTA, N2O pulsed chemisorption and FTIR studies. The BET and XRD and DTA showed that pre-calcination of TiO2 stabilised the support, but coalescence of particles was observed in TiO2 that was not subjected to any thermal pre-treatment as evidenced by crystallite growth. Similarly, XPS, FTIR and TPR proved the formation of Cu2O particles on the surface of pre-calcined TiO2. On the other hand, the absence of pre-calcination step resulted in interring of Cu species within the grown anatase crystallites that hindered their proper distribution over TiO2, helped in its inactiveness in the photoreduction of nitrate. However, the prepared material using pre-calcined TiO2 showed the overall nitrate and oxalic acid removal efficiency of 31 and 70% with N2 and NH4+ selectivity of 44.9 and 55.1 %, respectively. The results provide insight into the significance of activity-structure relation, inferring that the two surfaces were chemically not similar. Thus, as even supported by adsorption experiment, difference in photocatalytic behaviour amongst the prepared materials was a function of crystallinity, particle size, absence of surface defect and high energy sites.
关键词： Nitrate,photocatalyst,photoremediation,metal oxide-support interaction,oxalic acid
更新于2025-11-19 16:56:35
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A Novel Phytantriol-Based Lyotropic Liquid Crystalline Gel for Efficient Ophthalmic Delivery of Pilocarpine Nitrate
摘要： The purpose of this paper was to investigate the potential of liquid crystalline (LC) gels for ophthalmic delivery, so as to enhance the bioavailability of pilocarpine nitrate (PN). The gels were prepared by a vortex method using phytantriol and water (in the ratio of 73:27 w/w). Their inner structures were con?rmed by crossed polarized light microscopy, small-angle X-ray scattering, attenuated total re?ectance-Fourier transform infrared spectrum, and rheology. The in vitro release studies revealed that PN could keep sustained release from the gels over a period of 12 h. The ex vivo apparent permeability coef?cient of the gels demonstrated a 3.83-folds (P < 0.05) increase compared with that of eye drops. The corneal hydration levels of the gel maintained in the normal range of 79.46 ± 2.82%, hinting that the gel could be considered non-damaging and safe to the eyes. Furthermore, in vivo residence time evaluation suggested that a better retention performance of LC gel was observed in rabbit’s eyes compared to eye drops. In vivo ocular irritation study indicated that LC gel was nonirritant and might be suitable for various eye applications. In conclusion, LC gels might represent a potential ophthalmic delivery strategy to overcome the limitations of eye drops.
关键词： ophthalmic delivery,pilocarpine nitrate,cubic phase,liquid crystalline gel,phytantriol
更新于2025-09-23 15:23:52
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Night-Time Oxidation of a Monolayer Model for the Air–Water Interface of Marine Aerosols—A Study by Simultaneous Neutron Reflectometry and in Situ Infra-Red Reflection Absorption Spectroscopy (IRRAS)
摘要： This paper describes experiments on the ageing of a monolayer model for the air–water interface of marine aerosols composed of a typical glycolipid, galactocerebroside (GCB). Lipopolysaccharides have been observed in marine aerosols, and GCB is used as a proxy for these more complex lipopolysaccharides. GCB monolayers are investigated as pure films, as mixed films with palmitic acid, which is abundant in marine aerosols and forms a stable attractively mixed film with GCB, particularly with divalent salts present in the subphase, and as mixed films with palmitoleic acid, an unsaturated analogue of palmitic acid. Such mixed films are more realistic models of atmospheric aerosols than simpler single-component systems. Neutron reflectometry (NR) has been combined in situ with Fourier transform infra-red reflection absorption spectroscopy (IRRAS) in a pioneering analysis and reaction setup designed by us specifically to study mixed organic monolayers at the air–water interface. The two techniques in combination allow for more sophisticated observation of multi-component monolayers than has previously been possible. The structure at the air–water interface was also investigated by complementary Brewster angle microscopy (BAM). This study looks specifically at the oxidation of the organic films by nitrate radicals (NO3?), the key atmospheric oxidant present at night. We conclude that NO3? oxidation cannot fully remove a cerebroside monolayer from the surface on atmospherically relevant timescales, leaving its saturated tail at the interface. This is true for pure and salt water subphases, as well as for single- and two-component films. The behaviour of the unsaturated tail section of the molecule is more variable and is affected by interactions with co-deposited species. Most surprisingly, we found that the presence of CaCl2 in the subphase extends the lifetime of the unsaturated tail substantially—a new explanation for longer residence times of materials in the atmosphere compared to lifetimes based on laboratory studies of simplified model systems. It is thus likely that aerosols produced from the sea-surface microlayer at night will remain covered in surfactant molecules on atmospherically relevant timescales with impact on the droplet’s surface tension and on the transport of chemical species across the air–water interface.
关键词： palmitic acid,monolayer,neutron,nitrate radical,palmitoleic acid,reflectivity,aerosol,infra-red,cerebroside,Brewster angle microscopy
更新于2025-09-23 15:23:52
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Fabrication of fine-grained undoped Y2O3 transparent ceramic using nitrate pyrogenation synthesized nanopowders
摘要： Y2O3 ceramic is a promising optical material for mid-infrared (IR) windows and domes. Improvements in the mechanical and thermal performance of this material have become urgent if it is to perform adequately under extreme conditions. Herein, Y2O3 nanopowders were produced through the nitrate pyrogenation method. The final Y2O3 transparent ceramics were fabricated with a hybrid sintering method combining low temperature presintering and a subsequent hot isostatic pressing (HIP) treatment. The synthesis of nanopowders and the fabrication of the final ceramic products were investigated in detail. The Y2O3 ceramic sample that was presintered at 1350 °C provided the optimum microstructure for HIP treatment and resulted in an average grain size of 0.5 μm. Owing to the reduced grain size, the flexure strength and Vickers hardness of the sample were improved to 180 MPa and 8.4 GPa, respectively. Furthermore, the achieved pure Y2O3 ceramic demonstrated an excellent thermal conductivity at high temperature.
关键词： Nanopowders,Y2O3,Nitrate pyrogenation,Fine-grained transparent ceramic
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - A Device for Rapid Measurement of Nitrate Levels in Aqueous Solutions Based on Spectrophotometric Method
摘要： Method and device for rapid measurement of nitrate levels in aqueous solutions based on spectrophotometric method. The proposed method was realized with irradiation of test sample and measuring its optical density in the ultraviolet at three wavelengths.
关键词： UV-LEDs,nitrate-ions,water,measurement of nitrate,ultraviolet spectroscopy
更新于2025-09-23 15:22:29
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Reflective SPR Sensor for Simultaneous Measurement of Nitrate Concentration and Temperature
摘要： In this paper, a reflective fiber optic sensor based on surface plasmon resonance (SPR) was proposed to measure nitrate concentration and temperature simultaneously. The sensor adopted reflective structure, and used gold film as metal film for exciting SPR. Then, Cu-nanoparticles/carbon nanotubes composite film was used as sensitive material to measure nitrate concentration, and it was coated on the surface of the gold film by the dip coating method. Finally, polydimethylsiloxane was coated on part of the sensing probe to produce two independent resonance dips in the output spectrum. When the nitrate concentration and temperature changed, the two resonance dips would all move, but with different sensitivities. By monitoring the wavelength shifts of the two dips, the nitrate concentration and temperature could be measured simultaneously with using the dual-wavelength matrix method. Experimental results demonstrated that the measurement sensitivity of the nitrate concentration could reach 3.25 nm/lg[M], and the temperature measurement sensitivity was ?2.02 nm/°C. Moreover, the sensor had high-mechanical strength and was easy to package, which could be applied to remote measurement field.
关键词： reflective surface plasmon resonance (SPR),optical fiber sensor,Nitrate concentration,simultaneous measurement,temperature
更新于2025-09-23 15:22:29
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Silica aerogel membranes fabricated using removable nitrocellulose scaffolds
摘要： Two different methods were developed to generate silica-based aerogel membranes using nitrocellulose scaffolds. The first method involved incorporating fibers of nitrocellulose (NC) into the sol prior to gelation. NC fibers were either removed using a solvent during aging or calcining after aerogel formation to produce reticulated micron-sized channels in the aerogels. In the second method, an NC lacquer was mixed with the sol, and the mixture separated into a NC-rich phase and a sol-rich phase. The NC phase was subsequently removed from the aerogel using a solvent, creating aerogels with interconnected porosity. Aerogels were prepared from tetraethyloxysilane (TEOS) as a precursor and methyltriethoxysilane (MTES) as a co-precursor. Replacing TEOS with 25 vol% MTES increased the mechanical stability, allowing for greater ease of handling. Additionally, the more open network of the MTES gels led to higher helium gas permeability than that for the pure TEOS gels.
关键词： Silica membrane,Interconnected porosity,Nitrocellulose template,Cellulose nitrate,Silica aerogel
更新于2025-09-23 15:22:29
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Spectrophotometric determination of nitrate in hypersaline waters after optimization based on the Box-Behnken design
摘要： Monitoring dissolved nitrate (NO3?) concentrations is essential for conservation efforts in aquatic ecosystems. Spectrophotometric methods are a widely accepted approach for NO3? analysis. They detect NO3? as a colored diazo complex after reduction to nitrite (NO2?) and its consequent reaction with the so-called Griess reagent. This method is commonly used for freshwater and saline water samples, even though it requires applying a heavy metal in powder form (cadmium) or high concentrations of heavy metal salts (vanadium-III), as a reductant. There has been little discussion about applying these methods for hypersaline samples. This study optimizes an existing method for use in high saline conditions based on the Griess reaction. Five factors were studied: incubation temperature, reaction time, concentration of EDTA, concentration of trisodium citrate, and concentration of reductant (VCl3). Optimal conditions were obtained by using the Box-Behnken design and included using VCl3 17.5 mM, trisodium citrate 70 mM, and an incubation temperature of 60 °C for 40 min. These conditions provided a linear range from 0.55 μM to 50 μM NO3?. The method showed a moderate precision (ranging from 4.3% to 15.4%). The proposed protocol was tested with hypersaline natural samples and showed recovery rates between 92.6% and 100.1%. This protocol for NO3? determination is the first specifically described for hypersaline samples.
关键词： Hypersaline water,Nitrate analyses,Griess reaction,Vanadium chloride,Box-Behnken design
更新于2025-09-23 15:22:29
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Optical, Structural and Electrical Studies of Biopolymer Electrolytes Based on Methylcellulose Doped with Ca(NO <sub/>3</sub> ) <sub/>2</sub>
摘要： The intention of this research is to study effect of the different weight percent (wt%) of calcium nitrate, Ca(NO3)2 (CN) salt into biopolymer of Methylcellulose (MC). MC-CN solid biopolymer electrolyte was prepared by using casting technique. The concentrations of CN salt were prepared between 5 to 25 wt%. The optical and electrical characteristics of the samples were study by using Fourier Transform-Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Electrical Impedance Spectroscopy (EIS). The highest conductivity of the samples was containing 25 wt% of CN is 2.21X10-7 Scm-1. The optical study by using FTIR shows that the CN salt act as the conducting ions devoid of effect the molecular structure of the polymer. Additionally, the data of XRD revealed that MC-CN an amorphous phase.
关键词： EIS,Methylcellulose,Biopolymer Electrolytes,FTIR,XRD,Calcium Nitrate
更新于2025-09-23 15:21:01
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Photoactive ZnO nanosuspension for intensification of organics contaminations decomposition
摘要： In this work the photoactive properties of the aqueous suspension containing ZnO nanoparticles and zinc nitrate have been studied. The mechanism of organics photodecomposition at the presence of prepared suspension was studied by the measurements of spectral dependencies of Chicago Sky Blue dye photodecomposition. It was found that dye photodecomposition proceeds in three different photochemical processes: 1) the direct photodecomposition of organic molecules; 2) oxidation of dye molecules by reactive oxygen species which are the product of nitrate anions photodecomposition; 3) photocatalytic action of ZnO nanoparticles.
关键词： ZnO,Nanoparticle,Photocatalytic properties,Zinc nitrate
更新于2025-09-23 15:21:01