Surface Of Glass Beads Research Articles

Removal of elemental mercury by TiO2doped with WO3 and V2O5 for their photo- and thermo-catalytic removal mechanisms

The catalytic removal of Hg(0) was investigated to ascertain whether the catalysts could simultaneously possess both thermo- and photo-catalytic reactivity. The immobilized V2O5/TiO2 and WO3/TiO2 catalysts were synthesized by sol-gel method and then coated on the surface of glass beads for catalytic removal of Hg(0). They were also characterized by SEM, BET, XRD, UV-visible, and XPS analysis, and their catalytic reactivity was tested under 100-160 °C under the near-UV irradiation. The results indicated that V2O5/TiO2 solely possessed the thermo-catalytic reactivity while WO3/TiO2 only had photo-catalytic reactivity. Although the synthesis catalytic reactivity has not been found for these catalysts up to date, but compared with TiO2, the removal efficiencies of Hg(0) at 140 and 160 °C were enhanced; particularly, the efficiency was improved from 20 % at 160 °C by TiO2 to nearly 90 % by WO3/TiO2 under the same operating conditions. The effects of doping amount of V2O5 and WO3 were also investigated, and the results showed that 10 % V2O5 and 5 % WO3/TiO2 were the best immobilized catalysts for thermo- and photo-catalytic reactivity, respectively. The effect of different influent concentrations of Hg(0) was demonstrated that the highest concentration of Hg(0) led to the best removal efficiencies for V2O5/TiO2 and WO3/TiO2 at 140 and 160 °C, because high Hg(0) concentration increased the mass transfer rate of Hg(0) toward the surface of catalysts and drove the reaction to proceed. At last, the effect of single gas component on the removal of Hg(0) was also investigated.

Geometrical-optics analysis of reflective glass beads applied to building coatings

Replacing highly reflective envelope materials, retro-reflective materials (RRMs) used as building coatings can help to fight the urban heat island effect. The common component of RRMs are mainly glass beads and prisms. The use of glass beads is relatively wider. This paper presents a study on the reflective principle of a single glass bead. Retro-reflective directional characteristics of a glass bead were evaluated by simulation. It showed that the reflective directional characteristics of glass beads are different for different refractive index of glass beads. Among the 3 refractive indexes evaluated, the retro-reflective directional characteristics of glass beads are the most remarkable when the index is 1.93. Compared to the refractive index of 1.93, both a lower refractive index and a higher refractive index have a much wider reflective distribution on the glass bead surface. The reflective directional properties are affected by the refractive index of the glass bead, but almost unaffected by the angle and direction of the incident light.

Adsorption of Silver Nanoparticles on Glass Beads Surface

Colloidal silver is widely used owing to its specific properties, which enable it to be applied in various fields. In this work, adsorption of commercially available silver nanoparticles (AgNPs; NanoSilver PVP 1000) on glass beads was investigated. The glass microspheres (70–110 μm) were used as model particles. The adsorption of AgNPs on the glass beads surface was investigated in terms of adsorbent dosage. The adsorption isotherm was determined with the adsorbent dosage of 100 g/l and the AgNPs in range 100–1000 mg/l. It was found that adsorption isotherm data best fitted the Langmuir model. Kinetics of AgNPs adsorption onto glass beads followed a pseudo-second-order model. The interaction between glass microspheres surface and polyvinylpyrrolidone (PVP)-coated AgNPs is due to hydrogen bonding with oxygen of carbonyl groups of PVP and silanol groups on the glass surface.

Stability of Three‐Phase Water‐Particle‐Oil Systems

AbstractThe stability of three‐phase systems consisting of oil and a solid phase dispersed in aqueous solutions is examined. To achieve a sufficiently hydrophobic surface of the solid particles, the surface of glass microspheres was modified with ionic surfactants. The destabilization kinetics profile was determined and the instability index (TSI) was calculated for each sample. In an oil‐free system, destabilization occurred very fast and there were no significant temporal profile changes for the samples modified with both cationic and anionic surfactants. For particles modified with cationic surfactant after the addition of oil, a decrease in TSI values with increasing surfactant concentration was observed as a result of oil agglomeration. Higher TSI values for bare particles modified with anionic surfactant reflected the behavior of oil droplets remaining in solution as they exhibit no attachment to the surface of glass beads.

Enhanced photocatalytic oxidation of gaseous elemental mercury by TiO2 in a high temperature environment

The photo-oxidation of Hg0 in a lab-scale reactor by titanium dioxide (TiO2) coated on the surface of glass beads was investigated at high temperatures. TiO2 was calcinated at four different temperatures of 300°C, 400°C, 500°C and 600°C (noted as Ti300, Ti400, Ti500 and Ti600) and characterized for its physicochemical properties. The calcinated TiO2 coating on the glass beads was then tested to compare the photo-oxidation efficiencies of Hg0 with an incident light of 365nm. The results showed that the oxidation efficiencies of Hg0 for Ti400 and Ti500 were higher than those of Ti300 and Ti600. To enhance the photo-oxidation efficiency of Hg0, Ti400 was selected to examine the wave lengths (λ) of 254nm, 365nm and visible light with various influent Hg0 concentrations. The effects of irradiation strength and the presence of oxygen on the photo-oxidation efficiency of Hg0 were further investigated, respectively. This study revealed that the wave length (λ) of 254nm could promote the photo-oxidation efficiency of Hg0 at 140 and 160°C, while increasing the influent Hg0 concentration and could enhance the photo-oxidation rate of Hg0. However, the influence of 5% O2 present in the flue gas for the enhancement of Hg0 oxidation was limited. Moreover, the intensity of the incident wave length of 365nm and visible light were demonstrated to boost the photo-oxidation efficiency of Hg0 effectively.

Effect of Surface Preparation on the Microstructure, Adhesion, and Tensile Properties of Cold-Sprayed Aluminum Coatings on AA2024 Substrates

Commercially pure aluminum coatings (CP-Al) were applied to AA 2024-T351 substrates utilizing the cold spray process using different surface preparation methods and carrier gases; the resulting microstructures and mechanical properties were investigated. Substrate preparation methods were examined to understand the effect of substrate roughness on coating properties, to minimize embedded grit, and to identify the surface preparation method that yielded the best combination of coating properties. Three substrate roughing preparations, glass bead, SiC grit, and alumina grit blast, were examined while utilizing both helium and nitrogen as carrier gases in the cold spray process. Coatings that were oxide free, possessing densities greater than 99% were achieved, with the mean coating porosity ranging 0.1-0.5%. The highest mean adhesion strength was 42 MPa for the nitrogen gas and 20 MPa for the helium gas, both using glass bead surface preparation. For the nitrogen process gas samples, the surface preparation methods that produced high pull strengths correlated to bend test specimens that showed no signs of cracking on surfaces or edges. The overall best combination of mechanical property results was achieved with coatings prepared by glass bead surface roughening using nitrogen as a carrier gas.

Effects of grain angularity on NaCl precipitation in porous media during evaporation

AbstractThree dimensional pore‐scale analysis was carried out using X‐ray microtomography to investigate the effects of grain angularity on NaCl precipitation dynamics and patterns during evaporation from saline porous media. To do so, quartz sand and glass beads with almost similar average particle size and porosity were used enabling us to constrain the effects of grain angularity on NaCl precipitation since the glass beads were spherical and smooth whereas the sand consisted of irregularly shaped grains. Presence of angularity resulted in different pore sizes and shapes influencing the dynamics of evaporation and NaCl precipitation. Our results demonstrate that the preferential evaporation exclusively in fine pores at the surface of porous media results in discrete efflorescence. We observed a higher cumulative NaCl precipitation in the case of glass beads at the early stages of precipitation due to the presence of a fewer number of evaporation sites at the surface. This phenomenon resulted in formation of a thicker and more discrete NaCl crust at the surface of glass beads compared to sand grains. Also, computed water saturation profiles reveals formation of a wider unsaturated zone above the receding drying front in the case of sand compared to glass beads due to the presence of finer pores affecting the capillary flow though the partially wet zone. Our results provide new insights regarding the effects of grain angularity on NaCl precipitation dynamics and patterns during evaporation from saline porous media.

Surface modified glass beads as model carriers in dry powder inhalers—Influence of drug load on the fine particle fraction

The relationship between surface coverage and in vitro respirable fraction—often referred to as fine particle fraction (FPF)—of dry powder inhaler (DPI) formulations for the therapy of asthma was investigated using an artificial lung, the next generation impactor (NGI). Therefore mixtures with 100%, 50% and 25% calculated surface coverage of physically and chemically modified glass beads as model carrier and spray dried salbutamol sulfate as active pharmaceutical ingredient (API) have been prepared. In any of these cases the actual surface coverage was lower than the calculated surface coverage as a certain amount of API particles adheres to the mixing container wall instead of the glass bead surface. Moreover, API particles detach from the glass bead surface during capsule filling and transport resulting in even lower true surface coverage at the moment when the NGI experiments are performed. When investigating the FPF this true surface coverage has to be taken into account. The FPF increased more or less linearly with increasing surface coverage of the surface modified glass beads but the slopes of the lines are different depending of the carriers used. This can be attributed to the distribution of active sites on the glass bead surface that is individually depending on the surface modification applied and the processing time. However the influence of surface coverage on FPF is also influenced by the choice of the carrier particles. Compared to untreated glass beads physically modified glass beads show increased FPFs whereas chemically modified glass beads show lower FPFs.

Synthesis of TS-1 on porous glass beads for catalytic oxidative desulfurization

Abstract Porous glass supported with titanium silicalite (TS-1) particles were successfully prepared and used for oxidative desulfurization (ODS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Uniform-sized TS-1 particles were homogeneously dispersed on the surface of the porous glass beads. Effects of reaction duration, catalyst content, initial concentration, oxidant amount, and temperature on conversions were investigated. The prepared catalysts showed excellent catalytic performance. The optimal mole ratio of oxidant-to-DBT was 10 or 15. Complete conversion was obtained within 3 min at 343 K using catalyst with Ti content of 0.507 wt.%. Compared with other studies, the space–time yield was increased by one order of magnitude without any addition of solvent or metal nanoparticles. Experimental results and computer simulations revealed that the coordinated state of Ti species has a key role in the catalytic activity. Spent catalyst would be regenerated by heating at high temperature, no decrease was observed in catalytic activity after three cycles.

Characterization of Glass Beads Surface Modified with Ionic Surfactants

Knowledge of the wetting characteristic of mineral surfaces is very important in enhancing the efficiency of separation of valuable minerals from gangue using froth flotation or oil agglomeration. In this paper a capillary rise technique was used to characterize the glass beads surface modified with cationic surfactant. The glass microspheres were used as model particles with a spherical shape and smooth surface to eliminate the roughness effect. The value of the contact angle for water was found to be 21.5 for unmodified beads, and 61.8, 89.7, 68.4 for 0.1, 1.0, 10 mg/gsolid of CTAB, and 39.8, 68.6, 87.9 for 0.1, 1.0, 10 mg/gsolid of DDAHCl, respectively. Data revealed that the adsorption of surfactant onto glass beads decreased the value of the electron donor component, γ-, which defines the hydrophobicity of the surface. Also, the property of the surface was investigated by flotation and oil agglomeration experiments. It was observed that particles with low value of contact angle for water and high for 1-bromonaphthalene and low value of γ- were floated with a recovery equal to 91.1 and 83.1% for CTAB and DDAHCl, respectively, and effectively agglomerated. This indicates that the capillary rise method can be successfully used to predict the wetting properties of solid particles in mineral processing.

Colloid mobilization and transport during capillary fringe fluctuations.

Capillary fringe fluctuations due to changing water tables lead to displacement of air-water interfaces in soils and sediments. These moving air-water interfaces can mobilize colloids. We visualized colloids interacting with moving air-water interfaces during capillary fringe fluctuations by confocal microscopy. We simulated capillary fringe fluctuations in a glass-bead-filled column. We studied four specific conditions: (1) colloids suspended in the aqueous phase, (2) colloids attached to the glass beads in an initially wet porous medium, (3) colloids attached to the glass beads in an initially dry porous medium, and (4) colloids suspended in the aqueous phase with the presence of a static air bubble. Confocal images confirmed that the capillary fringe fluctuations affect colloid transport behavior. Hydrophilic negatively charged colloids initially suspended in the aqueous phase were deposited at the solid-water interface after a drainage passage, but then were removed by subsequent capillary fringe fluctuations. The colloids that were initially attached to the wet or dry glass bead surface were detached by moving air-water interfaces in the capillary fringe. Hydrophilic negatively charged colloids did not attach to static air-bubbles, but hydrophobic negatively charged and hydrophilic positively charged colloids did. Our results demonstrate that capillary fringe fluctuations are an effective means for colloid mobilization.

Covalent Attachment of Mechanoresponsive Luminescent Micelles to Glasses and Polymers in Aqueous Conditions

Covalent attachment of mechanoresponsive luminescent organic or organometallic compounds to other materials is a promising approach to develop a wide variety of mechanoresponsive luminescent materials. Here, we report covalently linkable mechanoresponsive micelles that change their photoluminescence from yellow to green in response to mechanical stimulation under aqueous conditions. These micelles are composed of a dumbbell-shaped amphiphilic pyrene derivative having amine groups at the peripheral positions of its dendrons. Using a well-established cross-linker, the micelles were covalently linked via their peripheral amine groups to the surface of glass beads, polylactic acid (PLA) beads, and living cells under aqueous conditions. Vortexing of glass beads bearing the micelles in a glass vial filled with water caused a photoluminescence color change from yellow to green. PLA beads bearing the micelles showed no change in photoluminescence color under the same conditions. We ascribe this result to the lower density and stiffness of the PLA beads, because the color of the PLA beads changed on vortexing in the presence of bare glass beads. HeLa cells and HL-60 cells bearing the micelles showed no obvious photoluminescence color change under vortexing. The structure, photophysical properties, and mechanism of photoluminescence color change of the micellar assemblies were examined.

Asphaltene precipitation, flocculation and deposition during solvent injection at elevated temperatures for heavy oil recovery

Asphaltene destabilization during solvent-based heavy oil and bitumen recovery applications is a common problem due to continuous changes of temperature, pressure, and oil composition. The effects of these characteristics on the recovery performance should be investigated for a wide range of solvent and oil types. In this paper, two heavy oil samples from fields in Alberta, Canada were destabilized using three different types of paraffin: propane, n-hexane, and n-decane. The solvent-based process was conducted at different reservoir conditions with alterations made to the temperature, pressure, and oil composition to determine the effect on asphaltene flocculation in the produced fluid and its deposition on the rock surface. Initially, experiments were carried out using a pressure, volume, and temperature (PVT) cell at different reservoir pressures and under different temperature conditions. Next, a Focused Ion Beam (FIB) and Scanning Electron Microscope (SEM) were used to characterize the morphology of the organic deposition on the glass beads surface through core flooding experiments. The results obtained through these two sets of experiments showed that temperature, pressure and oil compositions have a critical influence on asphaltene solubility. The PVT cell experiments and organic deposition surface roughness calculations were fundamentally important to explain the plugging formation in the reservoir under different operational conditions and with different oil types.

Studying the effect of nature of glass surface on immobilization of glucose isomerase

Immobilization of glucose isomerase (GI) (EC 5.3.1.5) has been carried out on non-porous glass surfaces using γ-aminopropyltriethoxysilane and polyethyleneimine as an activator and gluteraldehyde as cross linking agent for its potential use. Polyethyleneimine was found to be a superior immobilization activator than γ-aminopropyltriethoxysilane. Further, the effects of rough and smooth surfaces of non-porous glass beads on immobilization of glucose isomerase have been investigated. Polyethyleneimine on rough glass beads was found to be better activator material than that of γ-aminopropyltriethoxysilane. The prime objective of study was to immobilize glucose isomerase on an improved surface of non-porous glass beads which will give a significantly higher immobilization yield. After optimizing the parameters the immobilization yield increased from an initial value 29.43% to 79.6%.

In situ growth of TS-1 on porous glass beads for ammoximation of cyclohexanone

In this work, porous glass beads supported with TS-1 particles have been successfully prepared through in situ crystallization. TS-1 particles with uniform size and high crystallization are well dispersed on the surface of porous glass beads. As the support, porous glass beads exhibit the advantages of more manageable surface chemistry, better chemical and thermal stability, and larger specific surface area compared to that of conventional TS-1 films on flat or tubular supports. The experimental results show that the surface chemistry has profound influence on the morphology of TS-1 particles. The catalytic performance of the material was characterized with the reaction of ammoximation of cyclohexanone. Complete conversion was reached after 20min in a stirred tank reactor with the selectivity of 100%. Compared with the commercial catalyst, the reaction rate was increased by 54 times. The prepared catalysts were packed in a bed reactor, and the effects of space time, content of catalyst, temperature and pressure were investigated. The conversion of 48.1% was reached by the catalyst with TS-1 loading of 0.183wt.% at 353K and the space time of only 1.57min, and 100% recovery in catalytic activity after 5 cycles was demonstrated.

Abstracts from The Aerosol Society Drug Delivery to the Lungs 22Edinburgh International Conference CentreEdinburgh, Scotland, UKDecember 7–9, 2011

Summary Background: In bronchial challenge testing lung deposition of the stimulus may be poorly controlled due to incorrect use of nebulisers. Furthermore, the need for freshly prepared solutions burdens personnel and budget. In this study we aim to develop a dry powder alternative with higher reproducibility, better stability and lower costs than the current nebulisation test. Methods: Different pharmacological stimuli in the solid state were characterised on physico-chemical properties to determine the optimal conditions for processing and storage and were tested on their potential for dry powder inhalation. Adenosine and methacholine were micronised and dispersed with the Twincer ™ dry powder inhaler (DPI). Laser diffraction technique was applied to measure particle size distributions in the aerosol clouds. Results: Adenosine allows processing under ambient conditions. It was mixed with a lactose carrier in various mass ratios to produce adhesive mixtures and nucleus agglomerates. With three formulations, almost the entire dose range could be delivered with the Twincer ™ DPI. However, the process of preparing nucleus agglomerates might not be suitable for upscaling. Currently, spherical pellets are investigated as a more robust alternative. Methacholine is very hygroscopic and should therefore not be exposed to a high relative humidity. The methacholine particles leaving the Twincer ™ had an appropriate particle size distribution for inhalation. However, inhaler retention was high and should be reduced by controlling processing and storage conditions. Conclusions: Dry powder adenosine and methacholine seem promising alternatives for nebulisation. Methacholine must be handled under dry conditions. The highest doses of adenosine require further fine tuning.

Rapid degradation of solid‐phase bound peptides by the 20S proteasome

Proteasomes are cellular proteases involved in the degradation of numerous cellular proteins. The 20S proteasome is a cylindrical 28-mer protein complex composed of two outer heptameric α-rings forming the entrance for the protein substrate and two inner heptameric β-rings carrying the catalytic sites. Numerous in vitro studies have provided evidence that the 20S proteasome may degrade peptides of various lengths and even unfolded full-length polypeptide chains. However, a direct demonstration that the 20S proteasome may also cleave surface-attached immobilized peptides is lacking so far. To this end, we used a model system by coupling peptides from different source proteins covalently to the surface of glass beads and applied nanoLC/MS analysis to monitor the generation of proteolytic fragments in the presence of the 20S proteasome. Detectable amounts of cleavage products occurred within a few minutes indicating a much higher cleavage rate than observed with the same substrates in solution. Our finding lends support to the idea that proteasomes may directly degrade segments of membrane-bound proteins protruding into the aqueous phase.

Immobilization of biomolecules via ruthenium-catalyzed functionalization of the surface of silica with a vinylsilane

A new ruthenium complex catalyzed procedure for the efficient O -silylation of an SiO–H group on the silica surface of glass beads with controlled pores (CPG) using 1-trimethylsiloxy-3-dimethylvinylsilylpropane leading to Si–O–Si bond formation with the evolution of ethylene is described. The formed linker contains alkyl hydroxyl groups which can be reacted with a nucleoside phosphoramidite unit. The CPG support containing alkyl hydroxyl groups is successfully applied in automatic chemical synthesis of DNA fragments.

Influence of Heat Treatment for Coating of Nickel Plating on Hollow Glass Beads

Abstract Ni-plated hollow glass beads (GBs) were firstly prepared by pd-activation and electroless plating, then Ni-plated GBs were heat treated at 450°C for 1 h, Ni-plated GBs/PVC composite was fabricated by using polyvinyl chloride (PVC) adhesive. The microstructure and component of Ni-plated GBs surface were studied by scanning electron microscopy and energy dispersive spectrometer; heat insulation and reflectivity were detected by heat insulation instrument (home-made) and vector network analyzer. The results show coatings prepared by electroless plating were uniform, the nickel element in the coating was higher than 95.71% (mass fraction); with heat treatment, the surface roughness of coating was greater, and the reflectivity descended apparently, the D-value was 1 dB at the frequency of 15 GHz, but the influence of heat treatment for heat insulation of Ni-plated GBs was not great.

Low temperature preparation and characterization of TiO2 nanoparticles coated glass beads by heterogeneous nucleation method

Abstract Nano-TiO 2 /glass beads composite particles were prepared using heterogeneous nucleation method at low temperature (80 °C). The microstructure and micro-morphology of the as-prepared samples were characterized by SEM, XRD, Raman, XPS and BET. Different concentrations of phytic acid solution were used to modify the surfaces of glass beads before the precipitate of TiO 2 nanoparticles films. The results show that phytic acid plays an important role in the growth and micro-morphology of TiO 2 nanoparticles on the surfaces of glass beads. It was found that the specific surface areas of the composite particles were 4, 45 and 38 times that of the pristine glass beads when the concentration of phytic acid was 0, 3.0 and 6.0 g/L, respectively. XPS analysis shows that a TiO 2 layer is formed on the surfaces of glass beads through Ti O Si bonds. XRD and Raman spectra of the TiO 2 samples prepared by blank experiments without glass beads indicate that the crystal type of TiO 2 is anatase. The wear-resistance of silicone-modified epoxy resin was largely improved when nano-TiO 2 /glass beads composite particles were filled in the matrix, especially for the samples pretreated with 3.0 g/L phytic acid. The main reason concerns the fact that TiO 2 nanoparticles evenly loaded on the surface of glass beads were necked together, forming a rough and porous-structured coating layer when pretreated with 3.0 g/L phytic acid.