Modified Glass Beads Research Articles

Characterization Study of Dyes Photodegradation-Adsorption Products by TiO2-Chitosan Immobilized on Glass Beads using Flow System

Dyes have a complex molecular structure that is difficult to degrade and can persist for a long time in water bodies. This study examines more thoroughly the effectiveness of photodegradation-adsorption of dyes, kinetic aspects, isotherms, thermodynamics, identification of the structure of photodegradation products, and changes in environmental quality parameter values whose results are quite satisfactory. The combination of photodegradation-adsorption of dyes by TiO2-chitosan modified glass beads using a flow system has never been accomplished before. Flowing of the dye resulted in a dye degradation efficiency of 99%. The FESEM-EDX analysis shows that TiO2-chitosan has been coated onto the surface of the glass beads. R2 of kinetics MB, MO, RB are 0.99234, 0.9889, 0.9971, which were pseudo-first order. Qm, KL, R2 are 6.4382, 0.70533, 0.99923; 16.7364, 1.42059, 0.98816; 6.0078, 1.06973, 0.99889, respectively. The ∆H, ∆S, ∆S of -9.388, -0.024, -1.979; -27.182, -0.078, -3.592; -4.819, -0.017, 0.464 indicate the exothermic and spontaneous reaction. COD, TOC, pH, turbidity values have reached the threshold required by the government. The degradation products formed during the photodegradation-adsorption process were identified using LC-MS that the structure of the dye has been degraded to become simpler so that it is safely disposed of into the environment.

Immobilization of protease on modified glass beads by salinization: its use in commercial activity

Immobilization of protease on modified glass beads by salinization: its use in commercial activity

Production of galacto-oligosaccharides from whey permeate using β-galactosidase immobilized on functionalized glass beads

The conversion of whey permeates to galacto-oligosaccharides (GOS) was studied by the enzymatic action of β-galactosidase from Aspergillus oryzae in a continuous flow packed-bed reactor. A novel method of enzyme immobilization involving covalent immobilization of β-galactosidase on 3-aminopropyl triethoxysilane(3-APTES)-modified glass beads was developed by the cross-linking method. The pH and temperature dependence of the enzymatic efficiency of the glass bead-immobilized enzyme was compared with that of the free enzyme. Increased pH and thermal stabilities were observed for the immobilized enzyme versus the free enzyme. The reusability of the enzyme immobilized packed-bed reactor was studied and only about 4.6% of GOS yield was lost after eight reuses. Repeated cycle reactions were also carried out to improve the formation of GOS. The results showed that the GOS formation increased and a maximum GOS yield of 39.3% with 56.4% lactose conversion was obtained after the 2nd cycle of passing.

Effect of the properties of oil, particles, and water on the production of Pickering emulsions

Oil-in-water Pickering emulsions were prepared using a standard mixing configuration. Emulsification experiments were performed in an unbaffled tank using an off-centered pitched-blade turbine. Regular and modified glass beads were used as a stabilizer, and their size, concentration, and wettability effects were investigated as were oil viscosity and the properties of the aqueous phase (pH and salinity). Our findings highlighted the importance of the stabilization mechanism in the emulsification process, which is different from that of surfactant-based systems. The stabilization mechanism can be divided into four steps: (1) droplet formation by breakage, (2) particle/droplet approach and collision, (3) particle adsorption, and (4) formation of the particle network. Emulsification efficiency was mainly quantified by size distribution measurements using a Mastersizer 3000 (Malvern). Our results showed that droplet stabilization is closely related to particle/droplet approach, collision, and initial adsorption and that it is highly sensitive to oil viscosity and particle size and wettability, while the properties of the aqueous phase influence stabilization mainly through their effect on particle interactions (flocculation). The smallest droplets with the narrowest distribution were obtained with small particles, low oil viscosities, and good oil/particle affinity. It was possible to modulate the effects of particle size and oil viscosity by increasing oil/particle affinity. We also showed that stabilization efficiency is dependent on the particle fraction.

Influence of surface characteristics of modified glass beads as model carriers in dry powder inhalers (DPIs) on the aerosolization performance

The aim of this work is to investigate the effect of surface characteristics (surface roughness and specific surface area) of surface-modified glass beads as model carriers in dry powder inhalers (DPIs) on the aerosolization, and thus, the in vitro respirable fraction often referred to as fine particle fraction (FPF). By processing glass beads in a ball mill with different grinding materials (quartz and tungsten carbide) and varying grinding time (4 h and 8 h), and by plasma etching for 1 min, glass beads with different shades of surface roughness and increased surface area were prepared. Compared with untreated glass beads, the surface-modified rough glass beads show increased FPFs. The drug detachment from the modified glass beads is also more reproducible than from untreated glass beads indicated by lower standard deviations for the FPFs of the modified glass beads. Moreover, the FPF of the modified glass beads correlates with their surface characteristics. The higher the surface roughness and the higher the specific surface area of the glass beads the higher is the FPF. Thus, surface-modified glass beads make an ideal carrier for tailoring the performance of DPIs in the therapy of asthma and chronically obstructive pulmonary diseases.

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.

Preparation and characterization of physically modified glass beads used as model carriers in dry powder inhalers

The aim of this work is the physical modification and characterization of the surface topography of glass beads used as model carriers in dry powder inhalers (DPIs). By surface modification the contact area between drug and carrier and thereby interparticle forces may be modified. Thus the performance of DPIs that relies on interparticle interactions may be improved. Glass beads were chosen as model carriers because various prospects of physical surface modification may be applied without affecting other factors also impacting interparticle interactions like particle size and shape. To generate rough surfaces glass beads were processed mechanically by friction and impaction in a ball mill with different grinding materials that were smaller and harder with respect to the glass beads. By varying the grinding time (4 h, 8 h) and by using different grinding media (tungsten carbide, quartz) surfaces with different shades of roughness were generated. Depending on the hardness of the grinding material and the grinding time the surface roughness was more or less pronounced. Surface roughness parameters and specific surface area were determined via several complementary techniques in order to get an enhanced understanding of the impact of the modifying procedure on the surface properties of the glass beads.

Chemical surface modification of glass beads for the treatment of paper machine process waters

Adsorption of detrimental contaminants on a solid sorbent is proposed to remove these contaminants from process waters to increase water recycling and reduce effluent loads in the papermaking industry. A self-assembly process of attaching (covalent grafting) cationic aminosilane molecules to glass beads was investigated. The existence and the hydrolytic stability of self-assembled monolayers and multilayers were confirmed by X-Ray Photoelectron Spectroscopy and contact angle measurements. Effects of reaction time and curing on aminosilane layer structures are also discussed. The curing step after silanization seems to be crucial in the hydrophobization of the quaternary ammonium silane coated onto glass beads, and curing could affect the final chemical structure of the ammonium groups of grafted organosilane. Results indicated that modified glass beads have a strong hydrophobicity, which is attributed to the hydrophobic property of the longest carbon chain grafted onto the glass surface. Adsorption of a model contaminant (stearic acid) onto chemically modified glass beads was determined using colloidal titration. Hydrophobic interactions could be the main driving force involved between the long carbon chains of stearic acid and the carbon chains of the aminosilane layers on glass bead surfaces. Finally, self-assembly processes applied onto glass beads may have two promising applications for papermaking and self-cleaning systems.

Simple method for detection of extremely diluted anti beta-casein antibodies from glass bead based receptors

The current work describes the elaboration of a simple, sensitive and reliable β-casein modified glass beads, for the detection and quantification of its specific antibody anti β-casein. This is an elementary receptor without electronic part, developed by grafting glass bead surface with the antigenic β-casein via 3-aminopropyltriethoxy silane and then glutaraldehyde as cross-linker. The whole is realized by a classical process, called in two steps and in mild conditions where chemical protocol is optimized for β-casein use. The detection and quantification of the specific reaction antibody–receptor is carried out by the technique of the second antibody labeled with horse radish peroxidase (HRP). Our receptor can detect the β-casein antibody present in the serum at dilutions up to a factor 10 7 in strong ionic strength medium. The same antibody of the same serum and in the same conditions can be detected by ELISA test at dilutions up to a factor 10 5. The whole test, after our receptor realization, takes about 5 h.

Surface modification of glass beads with glutaraldehyde: Characterization and their adsorption property for metal ions

In this study, a new material that adsorbs the metal ions was prepared by modification of the glass beads surfaces with glutaraldehyde. First, the glass beads were etched with 4M NaOH solution. Then, they were reacted with 3-aminopropyl-triethoxysilane (APTES). Finally, silanized glass beads were treated with 25% of glutaraldehyde solution. The characterization studies by using Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA), elemental analysis and Scanning Electron Microscopy (SEM) indicated that modification of the glass bead surfaces was successfully performed. The adsorption studies exhibited that the modified glass beads could be efficiently used for the removal of the metal cations and anion (chromate ion) from aqueous solutions via chelation and ion-exchange mechanisms. For both Pb(II) and Cr(VI), selected as model ions, the adsorption equilibrium was achieved in 60 min and adsorption of both ions followed the second-order kinetic model. It was found that the sorption data was better represented by the Freundlich isotherm in comparison to the Langmuir and Redlich-Peterson isotherm models. The maximum adsorption capacities for Pb(II) and Cr(VI) were 9.947 and 11.571 mg/g, respectively. The regeneration studies also showed that modified glass beads could be re-used for the adsorption of Pb(II) and Cr(VI) from aqueous solutions over three cycles.

Glass bead grafting with poly(carboxylic acid) polymers and maleic anhydride copolymers

AbstractGlass beads were etched with acids and bases to increase the surface porosity and the number of silanol groups that could be used for grafting materials to the surfaces. The pretreated glass beads were functionalized using 3‐aminopropyltriethoxysilane (APS) coupling agent and then further chemically modified by reacting the carboxyl groups of carboxylic acid polymers with the amino groups of the pregrafted APS. Several carboxylic acid polymers and poly(maleic anhydride) copolymers, such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(styrene‐alt‐maleic anhydride) (PSMA), and poly(ethylene‐alt‐maleic anhydride) (PEMA) were grafted onto the bead surface. The chemical modifications were investigated and characterized by FT‐IR spectroscopy, particle size analysis, and tensiometry for contact angle and porosity changes. The amount of APS and the different polymer grafted on the surface was determined from thermal gravimetric analysis and elemental analysis data. Spectroscopic studies and elemental analysis data showed that carboxylic acid polymers and maleic anhydride copolymers were chemically attached to the glass bead surface. The improved surface properties of surface modified glass beads were determined by measuring water and hexane penetration rates and contact angle. Contact angles increased and porosity decreased as the molecular weights of the polymer increased. The contact angles increased with the hydrophobicity of the attached polymer. The surface morphology was examined by scanning electron microscopy (SEM) and showed an increase in roughness for etched glass beads. Copyright © 2007 John Wiley & Sons, Ltd.

Compression of Langmuir Films Composed of Fine Particles: Collapse Mechanism and Wettability

The collapse mechanism of microparticulate Langmuir films was studied experimentally in the present work. Using a Wilhelmy film balance, surface pressure vs area isotherms were determined, and the particle removal during the compression was examined by video-microscope and by naked eye. Upon compressing partially wettable 75 microm diameter surface modified glass beads at liquid (water or aqueous surfactant solution)-air (or n-octane) interfaces, different collapse mechanisms were visualized depending on the wettability of the particles. At low contact angles (below 40 degrees ) irreversible particle removal was observed as a consequence of a particulate line-by-line collapse mechanism. At higher contact angles a buckling-type collapse mechanism was revealed without particle removal from the liquid interface. In the case of irreversible particle removal we assessed the contact angles from the nondissipative part of the isotherm. These values were found to be in reasonable agreement with those determined directly on the beads.

Surface modification of glass beads with poly(acrylic acid)

Non-porous P2 glass beads were etched with sodium hydroxide to increase the number of silanol groups that could be used to modify the surface. The etched glass beads were then functionalized with 3-aminopropyltriethoxysilane (APS) and/or glycidoxypropyltrimethoxysilane (GPS). The surface of the glass beads were further modified with poly(acrylic acid) (PAA) by reacting the carboxyl groups on PAA with the amino groups of the pregrafted APS. The chemical modifications were characterized by FT-IR spectroscopy, particle size analyzer and tensiometry for contact angle and porosity measurements. Five different molecular weight PAA polymers ranging from 2000 to 3,000,000 were grafted with less than expected increase of grafted PAA with molecular weight. The amount of APS and PAA on the surface was determined from thermogravimetric analysis and elemental analysis data. The surface properties of the surface modified glass beads were determined by measuring water and hexane penetration rate and contact angle. The surface morphology was examined by scanning electron microscopy. Copyright © 2006 John Wiley & Sons, Ltd.

Solid surface mapping by inverse gas chromatography

Inverse gas chromatography (IGC) at infinite dilution, is a technique for characterising solid surfaces. Current practice is the injection of n-alkane homologous series to obtain the free energy of adsorption of the CH 2 group, from which the London component of the solid surface free energy, γ S d , is calculated. A value around 40 mJ/m 2 is obtained for poly(ethylene), and 30 mJ/m 2 for a clean glass fibre, while the potential surface interactivity of a glass fibre is far greater than that of poly(ethylene). A specific component of the surface, in mJ/m 2, should be calculated in order to obtain significant parameters. As applied up to date, when calculating the specific component of the surface energy, the fact that W a sp energy values are in a totally different scale than AN or DN values is a major drawback. Consequently, Ka and Kb values obtained are in arbitrary energy units, different from those of the London component measured by injecting the n-alkane series. This paper proposes a method to obtain Ka and Kb values of the surface in the same energetic scale than the London component. The method enables us to correct the traditional London component of a solid, obtaining a new value, where the amount of W a C H 2 accounting for Debye interactions with polar sites, is excluded. As a result, an approach to surface mapping is performed in several different substrate materials. We show results obtained on different solid surfaces: poly(ethylene), clean glass fibre, glass beads, chemically modified glass beads and carbon fibre.

Enhanced Interfacial Adhesion between PPO and Glass Beads in Composites by Surface Modification of Glass Beads via In Situ Polymerization and Copolymerization

Glass beads were modified with vinyl triethoxyl silane (VTES) followed by in situ copolymerization with styrene (St) and by direct modification with St via in situ polymerization. It was seen that the presence of glass beads did not inhibit the polymerization of St, and FT-IR spectra confirmed that the polystyrene (PS) molecules were grafted on the surfaces of glass beads. When the modified glass beads were filled in a poly(phenylene oxide) (PPO) matrix, the PS segments on the surfaces of glass beads clearly improved compatibility and enhanced interfacial adhesion between the PPO matrix and glass beads, which was responsible for the slightly increased glass transition temperature of the PPO component. Surface modifications, especially by in situ copolymerization of VTES and St, increased significantly notch impact strengths and marginal stiffness and tensile strengths of PPO/glass bead composites.

Effects of surface modification of glass beads with poly(acrylic acid)

Etched glass beads were functionalized with 3-aminopropyltriethoxysilane (APS) and glycidoxypropyltrimethoxysilane (GPS). The surface of glass beads were further modified with poly(acrylic acid) by reacting the carboxyl groups on poly(acrylic acid) with the amino groups of the grafted aminopropyltriethoxysilane. The modifications were characterized by FT-IR spectroscopy and tensiometry for contact angle and porosity measurements. Five different molecular weight PAA polymers ranging from 2,000 to 3,000,000 were grafted with less than expected increase of grafting% with molecular weight. The amount of poly(acrylic acid) (PAA) on the surface was determined from thermal gravimetric analysis and elemental analysis data. The surface properties of surface modified glass beads were determined by measuring water and hexane penetration rate and contact angle. The surface morphology was examined by scanning electron microscopy.

A modified glass bead compartment cultivation system for studies on nutrient and trace metal uptake by arbuscular mycorrhiza

A modified glass bead compartment cultivation system is described in which glass beads continue to be used in the hyphal compartment but are replaced by coarse river sand in the compartments for host plant roots and mycorrhizal hyphae. Arbuscular mycorrhizal (AM) associations were established using two host plant species, maize ( Zea mays L.) and red clover ( Trifolium pratense L.) and two AM fungi, Glomus mosseae and G. versiforme. When the standard and modified cultivation systems were compared, the new method yielded much more fungal tissue in the hyphal compartment. Using G. versiforme as the fungal symbiont, up to 30 mg of fungal dry matter (DM) was recovered from the hyphal compartment of mycorrhizal maize and about 6 mg from red clover. Multi-element analysis was conducted on samples of host plant roots and shoots and on harvested fungal biomass. Concentrations of P, Cu and Zn were much higher in the fungal biomass than in the roots or shoots of the host plants but fungal concentrations of K, Ca, Mg, Fe and Mn were similar to or lower than those in the plants. There were also significant differences in nutrient concentrations between the two AM fungi and these may be related to differences in their proportions of extraradical mycelium to spores. The high affinity of the fungal mycelium for Zn was very striking and is discussed in relation to the potential use of arbuscular mycorrhiza in the phytoremediation of Zn-polluted soils.

Wettability of Glass-Bead Surface Modified by Trimethylchlorosilane

The relationship between coverage of hydrophobic groups on modified glass bead surfaces and macroscopic properties such as wettability or dispersion ability has been demonstrated. The glass bead surfaces modified by trimethylsilyl (TMS) groups were obtained by the chemical reaction between trimethylchlorosilane molecules and surface silanols. The TMS coverage was estimated from carbon content by combustion gas analysis, using IR spectroscopy and the specific surface area determined by krypton adsorption. The macroscopic wettability of the samples for water was examined by floating tests and measuring contact angles. The results are summarized as follows. (1) The surface determination, employed in this study, enables one to measure small amounts of TMS groups on small-surface-area samples. (2) It was recognized from the results of the floating test and the contact angle measurement that macroscopic wettability changed markedly at the TMS coverage of about 50% of monolayer coverage. (3) The simulation and model of wetting can account for the wettability of a modified glass-bead particle surface. It was demonstrated that the wettability of material had a close relation to the bulkiness of modifier and the surface coverage on the molecular level.

Electrochemical Detection of African Swine Fever Virus in Pig Serum With a Competitive Separation Flow Injection Analysis-immunoassay

A competitive separation FIA-immunoassay was established to detect African Swine Fever Virus (ASFV) in infected pigs. The detection was based on the competition between a peroxidase (horseradish peroxidase, HRP) labelled monoclonal antibody and the specific pig polyclonals for the biotinylated virus protein VP73. The affinity reaction was performed in solution followed by electrochemical determination of the HRP activity in the FIA system. The sensitivity of this competitive separation assay was similar to the conventionally used microtiterplate ELISA for ASFV detection. For the monoclonal antibody 18BG3, the detection range was 1–80 ng ml - 1 with a concentration of 50% inhibition (C 50 ) at 6 ng ml - 1 . The immunological complex formed during this homogeneous incubation was trapped in a small column containing glass beads with streptavidin on their surface. The amount of captured HRP labelled antibodies was determined by the enzymatic turnover of hydroquinone and hydrogen peroxide to p-benzoquinone and H 2 O. The enzymatic product was electrochemically reduced at -100 mV vs. Ag/AgCl at a glassy carbon electrode. After each measurement the reactor was regenerated by a removal of the streptavidin bridge including the captured immunological complex (IC). The biotin modified glass beads could be reactivated with a new coating of streptavidin for the next affinity reaction. The determination could be performed automatically in the FIA system within 15 min. With this procedure more than 150 tests were performed with the same reactor without a significant loss of sensitivity.

Morphological and rheological properties of PS melts filled with grafted and ungrafted glass beads

AbstractGlass beads carrying different amounts of polystyrene (PS) grafted to their surface were prepared by solution and melt‐mixing processes. These beads are mixed with a nearly mono‐disperse PS. The morphology of polymers filled with different volume amounts, ϕ, of modified and unmodified glass beads was investigated by scanning electron microscopy (SEM). In the case of PS‐grafted glass beads, the fracture surfaces show cohesive failure. The rheological properties of these filled polymers were investigated by mechanical spectroscopy. The material functions, the storage modulus G″ and the loss modulus G″, for PS melts filled with unmodified beads can be presented in an invariant from, e.g., independent of temperature and concentration. The temperature‐shift factors follow WLF behavior, and the concentration shift factors a generalized Maron Pierce equation. The rheological material functions of melts filled with modified glass beads can be superposed for different temperatures. However, a concentration invariant representation is only possible in the frequency range belonging to the plateau region. For small frequencies, a systematic deviation occurs whose strength depends on the amount of polymer grafted to the filler surface. It is argued that this behavior may be attributed to an additional relaxation process originating from the hindered flow of the modified glass beads. This process has to be investigated in more detail in the future. © 1995 John Wiley & Sons, Inc.