Surface Of Glass Beads Research Articles

Chitosan‐Coated Glass Beads as Stabilizer of Insulin; A Novel Strategy for the Storage of Pharmaceutical Proteins

AbstractBesides the pharmaceutical protein production challenge, storing and transporting them between industrial sectors and the administration site have always been problematic. Insulin, an example of the most widely used therapeutic protein, aggregates into unstable larger particles and, in many cases, into amyloid fibrils under environmental stresses. In this study, chitosan was used to decorate the surface of glass beads (to produce Chi@GB) to increase the structural stability of insulin against environmental stresses. FT‐IR spectroscopy characterized the beads, and HPLC determined the chitosan loading. The results showed that the modified beads could inhibit insulin fibrillation. In addition, the beads can be used in biopharmaceutical containers of insulin or other proteins for long‐term storage of their commercial products.

Effective Strategy toward Obtaining Reliable Breakthrough Curves of Solid Adsorbents.

Metal-organic frameworks (MOFs) have demonstrated their versatility in a wide range of applications, including chemical separation, gas capture, and storage. In industrial adsorption processes, MOFs are integral to the creation of selective gas adsorption fixed beds. In this context, the assessment of their separation performance under relevant conditions often relies on breakthrough experiments. One aspect frequently overlooked in these experiments is the shaping of MOF powders, which can significantly impact the accuracy of breakthrough results. In this study, we present an approach for immobilizing MOF particles on the surface of glass beads (GBs) utilizing trimethylolpropane triglycidyl ether (TMPTGE) as a binder, leading to the creation of MOF@GB materials. We successfully synthesized five targeted MOF composites, namely, SIFSIX-3-Ni@GB, CALF-20@GB, UiO-66@GB, HKUST-1@GB, and MOF-808@GB, each possessing distinct pore sizes and structural topologies. Characterization studies employing powder X-ray diffraction and adsorption isotherm analyses demonstrated that MOFs@GB retained their crystallinity and 73-90% of the Brunauer-Emmett-Teller area of their parent MOFs. Dynamic breakthrough experiments revealed that, in comparison to their parent MOFs, MOF@GB configurations enhanced the accuracy of breakthrough measurements by mitigating pressure buildup and minimizing reductions in the gas flow rate. This work underscores the significance of meticulous experimental design, specifically in shaping MOF powders, to optimize the efficacy of breakthrough experiments. Our proposed strategy aims to provide a versatile platform for MOF powder processing, thereby facilitating more reliable breakthrough experiments.

Transport and retention of silica nanoparticles in glass-bead columns: effects of particle size, type, and concentration of ionic species

Silica nanoparticles (SiO2 NPs) have garnered substantial attention as versatile additives in saline fluids, finding application in areas like environmental remediation, wastewater treatment, enhanced oil recovery, and carbon geo-sequestration. Despite their potential, the intricate interaction between electrolyzed nanoparticles and porous media remains inadequately researched in these contexts. This study delves into the pivotal yet underexplored aspect of silica nanoparticle absorption behavior within porous media, a key determinant of their practical effectiveness. The research focuses on silica particles with dimensions of 10 nm and 50 nm, synthesized via hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in methanol. Employing packed glass bead columns as a surrogate for porous media, the study unravels the complex mechanisms governing nanoparticle transport and deposition. Comprehensive investigations encompass variations in particle sizes, ionic strength, and ionic species, resulting in the examination of 48 distinct flooding scenarios. UV/Vis spectrophotometry is used to quantify nanoparticle concentrations in effluents, elucidating their transport behavior within the porous media. Concurrently, pressure drop alterations across the media serve as indicators of particle plugging and changes in permeability. Intriguingly, specific conditions involving a nanofluid comprising 50 nm silica nanoparticles and 10,000 ppm of magnesium chloride exhibit pronounced permeability reduction, offering potential insights for optimizing applications. Particularly noteworthy is the unique reduction in silica particle retention on glass bead surfaces as salinity increases, especially in the presence of magnesium sulfate. A concentration of 5000 ppm magnesium sulfate induces a log-jamming mechanism, resulting in an amplified final-to-intermediate permeability ratio. Experimental outcomes align with observations from scanning electron microscopy, improving understanding of porous media retention mechanisms. This study contributes to a deeper understanding of interactions between nanoparticles and porous media, paving the way for enhanced application strategies.

PREPARATION AND PROPERTIES OF SiO2/Ag MICROBEADS USING ELECTROLESS PLATING METHOD

SiO2/Ag microbeads were synthesized using the electroless plating method by changing the addition order and the mixed method of electroless plating. Conducting composites were prepared using the prepared SiO2/Ag microbeads and unsaturated polyester resin as the fillers and substrate, respectively. The microstructure and properties of the prepared microbeads and composite were characterized with a scanning electron microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectrometer (EDS), particle size analyzer, DC milliohm meter and vector network analysis tester. Results show that the SiO2/Ag microbeads prepared with the reverse dropping electroless plating method achieved the best uniformity and integrity of the silver coating on the surfaces of glass beads, and its compaction resistance reached 138.80 mΩ·cm. When the ratio of the prepared SiO2/Ag microbeads and unsaturated polyester resin was 1:2, the obtained coating composite had a resistivity of 2.79 × 10–5 Ω·cm, showing good electromagnetic shielding performance.

In-situ study on the heterocoagulation between fine coal particles and coarse glass beads by the particle vision and measurement (PVM) techniques

Heterocoagulation between mineral particles is an important phenomenon in mineral processing. Although various characterization methods have been available for characterizing heterocoagulation, in-situ characterization techniques are still lacking. In the present work, a novel in-situ particle vision and measurement (PVM) system was developed to investigate heterocoagulation between coarse and fine particles, which is consistent with the common situation of mineral processing. The heterocoagulation between fine coal particles and coarse glass beads was observed at different pH values and stirring speeds. It was found that the heterocoagulation degree decreased with the increase of pH, which is consistent with the DLVO theoretical calculation results. The heterocoagulation degree decreased with the increase of stirring speed. This indicated that heterocoagulation can be inhibited by high intensity conditioning. Moreover, it was observed that the coated coal particles were not randomly distributed on the glass bead surface. Under certain hydrodynamic conditions, the coal particles were even more distributed at the rear of the glass bead. It is concluded that the microhydrodynamics has a significant effect on the collision frequency and heterocoagulation.

Synthesis and Evaluation of Engineering Properties of Polymer-Coated Glass Beads.

Modern construction projects are often challenging, which has increased the demand for innovative materials that ensure improved safety, durability, and functionality. To explore the potential of enhancing soil material functionality, this study synthesized polyurethane on the surface of glass beads and evaluated their mechanical properties. The synthesis of polymer proceeded according to a predetermined procedure, where the polymerization was confirmed through analysis of chemical structure by Fourier transform infrared spectroscopy (FT-IR) and microstructure observation by a scanning electron microscope (SEM) after complete synthesis. The constrained modulus (M) and the maximum shear modulus (Gmax) of mixtures with synthesized materials were examined by using an oedometer cell equipped with bender elements under a zero lateral strain condition. Both M and Gmax decreased with an increase in the contents of polymerized particles due to a decrease in the number of interparticle contacts and contact stiffness induced by the surface modification. The adhesion property of the polymer induced a stress-dependent change in M but was observed to have little effect on Gmax. Compared to the behavior of the rubber-sand mixtures, polymerized particles show the advantage of a smaller reduction of M.

Cover Picture: Chem. Eng. Technol. 4/2023

Chemical Engineering & TechnologyVolume 46, Issue 4 p. 597-597 Cover PictureFree Access Cover Picture: Chem. Eng. Technol. 4/2023 First published: 21 March 2023 https://doi.org/10.1002/ceat.202370401AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Template-assisted nucleation of peptides. Copyright: Vivek Verma et al./DOI: 10.1002/ceat.202200575 Peptide crystallisation is a sustainable purification strategy compared to the commonly used chromatography techniques. The presence of templates has been demonstrated to control and improve the nucleation rates of crystallising solutes. This work studies the templated crystallisation of glycine homopeptides using glass beads, both experimentally and using molecular modelling. The experimental results suggest that the nucleation rate of (poly)glycine increases with the increase in the number of the available functional groups. Molecular dynamics simulations confirmed that the residence time of the triglycine molecule on the surface of glass beads is sufficiently longer than glycine or diglycine. It was confirmed that larger molecules exhibit faster nucleation in the presence of glass beads due to an increased number of interactions as observed with the longest hydrogen bond lifetime for triglycine, followed by diglycine and glycine. Volume46, Issue4April 2023Pages 597-597 RelatedInformation

Miniaturized optimal incident light angle-fitted dark field system for contrast-enhanced real-time monitoring of 2D/3D-projected cell motions.

In the field of biology, dark field microscopy provides superior insight into cells and subcellular structures. However, most dark field microscopes are equipped with a dark field filter and a light source on a 2D-based specimen, so only a flat sample can be observed in a limited space. We propose a compact cell monitoring system with built-in dark field filter with an optimized incident angle of the light source to provide real-time cell imaging and spatial cell monitoring for long-term free from phototoxicity. 2D projection imaging was implemented using a modular condenser lens to acquire high-contrast images. This enabled the long-term monitoring of cells, and the real-time monitoring of cell division and death. This system was able to image, by 2D projection, cells on the surface thinly coated with multiwalled carbon nanotubes, as well as living cells that migrated along the surface of glass beads and hydrogel droplets with a diameter of about 160 μm. The optimal incident light angle-fitted dark field system combines high-contrast imaging sensitivity and high spatial resolution to even image cells on 3D surfaces.

Enhanced Solar Photocatalytic Activity of Thermally Stable I:ZnO/Glass Beads for Reduction of Cr(VI) in Tannery Effluent.

Chromium (VI) in tannery effluent is one of the major environmental concerns for the environmentalists due to the hazardous nature of Cr(VI) ions. To reduce Cr(VI) to Cr(III) as an innocuous moiety, pure and I-doped ZnO was grafted over the etched surface of glass beads by successive ionic layer adsorption and reaction (SILAR). Powdered, pure, and I-doped ZnO scrapped from the surface of glass beads was characterized for crystallinity, morphology, and elemental composition by XRD, SEM, TEM, and EDX. The optical properties of both photocatalysts revealed that owing to optimized iodine doping of ZnO, reduction in the bandgap was observed from 3.3 to 2.9 eV. The crystalline nano-bricks of I:ZnO adhered to glass beads were investigated to have remarkable capability to harvest sunlight in comparison to intrinsic ZnO nanodiscs. The thermal stability of I:ZnO was also found to be much improved due to doping of ZnO. The photocatalytic activities of ZnO/GB and I:ZnO/GB were compared by extent of reduction of Cr(VI) under direct natural sunlight (600–650 KWh/m2). The disappearance of absorbance peaks associated with Cr(VI) after treatment with I:ZnO/GB confirmed higher photocatalytic activity of I:ZnO/GB. The reaction parameters of solar photocatalytic reduction, i.e., initial pH (5–9), initial concentration of Cr(VI) (10–50 ppm), and solar irradiation time (1–5 h) were optimized using response surface methodology. The solar photocatalytic reduction of Cr(VI) to Cr(III) present in real tannery effluent was examined to be 87 and 98%, respectively, by employing ZnO/GB and I:ZnO/GB as solar photocatalysts. The extent of reduction was also confirmed by complexation of Cr(VI) and Cr(III) present in treated and untreated tannery waste with 1, 5-diphenylcarbazide. The results of AAS and UV/vis spectroscopy for the decrease in concentration of Cr also supported the evidence of higher efficiency of I:ZnO/GB for reduction of Cr(VI) in tannery effluent. Reusability of the fabricated photocatalyst was assessed for eight cycles, and magnificent extent of reduction of Cr(VI) indicated its high efficiency. Conclusively, I:ZnO/GB is a potential and cost-effective candidate for Cr(VI) reduction in tannery effluent under natural sunlight.

Glass Beads for Road Markings: Surface Damage and Retroreflection Decay Study

Road markings must be reflectorised with glass beads to be visible to drivers at night, retro-reflecting light from vehicle’s headlights, which is critical for road safety. Four commonly used types of glass beads were evaluated in a laboratory setting for retroreflectivity and their surfaces were analysed using optical and scanning electron microscopy. The glass beads were subjected to abrasion and a visual correlation was sought between the measured retroreflectivity and the surface damage. Scratching the glass bead surface with corundum in a rotary drum resulted in major differences in the rates of damage development, depending on the type of the glass beads, and it could be correlated with the rate of retroreflectivity decay. The relative results from abrasion testing were confirmed under tyre action during a turntable evaluation. Based on the outcomes of these tests, service lives, defined as maintaining appropriately high retroreflectivity, were predicted and used to calculate the consumption of raw materials—the basic sustainability parameter. It was shown that the use of ‘premium’ glass beads, enhanced with TiO2 and made in a proprietary process, provided the road marking system characterised by the lowest long-term consumption of resources.

Mechanical Stability Is Key for Large-Scale Implementation of Photocatalytic Surface-Attached Film Technologies in Water Treatment

Replacement of classical tertiary water treatment by chemical-free sunlight-driven photocatalytic units has been often proposed. Photocatalysts are required to be cost-effective, inert, chemically stable, reusable, and easy to separate and also that they are mechanically stable. The effect of mechanical stress on a photoactive TiO2 layer, and on its effectivity for degradation of phenol as a model pollutant, has been studied during photocatalytic water treatment using NUV–vis light. Sol–gel (SG) and liquid phase deposition (LPD) methods have been used to coat spherical glass beads with the photocatalyst (TiO2). Physicochemical characterization of coated glass beads has been performed by N2 adsorption–desorption isotherms, SEM, EDXS, and AFM. Phenol photocatalyzed degradation was carried out both in stirred batch and flow reactors irradiated with a medium-pressure Hg-vapor lamp (λ > 350 nm). Phenol concentration was determined by HPLC, and its photoproducts were identified using HPLC/MS. In the stirred batch reactor, all LPD-coated glass beads displayed higher catalytic activity than SG-coated ones, which increased with calcination temperature, 700°C being the most efficient temperature. Preliminary etching of the glass beads surface yielded dissimilar results; whereas, phenol photodegradation with SG-coated etched glass beads is twice faster than with unetched SG ones, the rate reduces to one-third using LPD etched instead of unetched LPD glass beads. Phenol photodegradation using LPD is similar both in stirred batch and flow reactors, despite the latter uses a lower catalyst load. LPD-etched catalyst was recovered and reused in the stirred batch reactor; its activity reduced sharply after the first use, and it also lost activity in successive runs, ca. 10% of activity after each “use and recover” cycle. In the flow reactor, activity loss after the first experiment and recycling (ca. 30%) was much larger than in the following runs, where the activity remained rather constant through several cycles. LPD is more adequate than SG for TiO2 immobilization onto glass beads, and their calcination at 700°C leads to relatively strong and reactive photocatalytic films. Still, TiO2-coated glass beads exhibited very low photoactivity compared to TiO2-P25 nanoparticles, though their separation is much easier and almost costless. The durability of the catalytic layer increases when using a flow reactor, with the pollutant solution flowing in a laminar regime through the photocatalyst bed. In this way, the abrasion of the photocatalytic surface is largely reduced and its photoactivity is better maintained.

Controlling glass bead surface functionality - Impact on network formation in natural edible polymer systems

Combining particles and polymers provides materials with unique mechanical properties. Hereby, the character of the particle surface is important for the network properties. However, particle-polymer interfaces of food systems are scarcely controllable. This often leads to an indefinite contribution on the network properties. Developing hybrid artificial systems by using inert particles with a well-defined coating represents a new approach in food science. Coating with functionalized silanes enables the imitation of naturally occurring chemical groups. A novel experimental approach involving nano- and macroscopic analytical techniques (X-ray photoelectron spectroscopy and contact angle) sheds light on the nature and the strength of the adsorption. Depending on the presented surface functionality, strong specific to weak unspecific adsorptions arise, e.g. amino-functionalized surfaces show strong interaction with protein, while almost no interaction was observed with an aliphatic surface. Based on these different particle adhesivenesses, the monitoring of network formation discloses a significant impact of particle surface functionality on network development of food matrixes. An increasing network development time (3.2–6.0 min, gluten protein-based) in combination with a decreasing network strength (874-464 mNm gluten protein-based) correlates with an increasing adhesiveness of particles. Thus, using functionalized particles clearly demonstrates the importance of particle surface functionality on network properties in food systems.

Silane treatment of drop-on glass-beads and their performance in two-component traffic paints

In this research, the surface of drop-on glass beads (GBs) was first etched, then modified using 3- trimethoxy silyl propyl methacrylate (MS) and trimethoxy vinyl silane (VS) through a sol-gel process to improve GBs’ adhesion to the two-component methyl methacrylate-based traffic paints (known as cold plastic paints). The etching was conducted in acidic, neutral, and basic conditions. Acidic etching condition was selected for the further experiments considering the highest number of OH groups provided by etching reaction on the surface of GBs. The FTIR and 13C-NMR spectroscopy were utilized to characterize chemical composition, and Atomic Force Microscopy (AFM) was used to evaluate the surface roughness / topography of the pretreated and silane-treated GBs. The amount of silane coated on the surface of the GBs was determined using thermogravimetric analysis (TGA). The dispersion of silane compounds on the surface of the treated GBs was assessed using Energy Dispersive X-Ray Analysis (EDXA). Neat and silane-treated GBs were then sprayed on freshly applied cold plastic paint samples using a designed lab spray device. Optical microscopy was used to evaluate the proper embedment depth of the GBs onto the surface of the paint samples. The abrasion test was performed in dry and wet conditions to evaluate the adhesion strength of neat and silane-treated GBs to the paint surface in normal and rainy weather. The coefficient of retroreflected luminance (RL) and the luminance coefficient under diffuse illumination (Qd) were measured to characterize the night and day retroreflective performance of cold plastic paints containing treated and untreated GBs. The abrasion test results showed the least weight loss in the paint markings containing drop-on VS-treated GBs (VS.GBs) in comparison to neat and MS-treated GBs (MS.GBs). This was assigned to increase in adhesion strength and interfacial interactions between VS.GBs and the polymeric matrix. The measured values of RL and Qd also confirmed the excellent maintenance of drop on VS.GBs on the surface of the two-component traffic paints.

Yellow thermoplastic road markings with high retroreflectivity: Demonstration study in Texas

Road markings are a niche category of industrial coatings with requirements related to both the coating itself and the layer of glass beads on top of it that furnish retroreflectivity (RL) – their key property, particularly needed during driving at night time and in rainy weather conditions. The most frequently used glass beads, with refractive index 1.5, are capable of delivering RL reaching only about 400 mcd/m²/lx in white and 200 mcd/m²/lx in yellow markings; very low retroreflectivity under wet conditions, seldom exceeding 50 mcd/m²/lx can be obtained. Recently introduced ‘premium’ glass beads, with refractive index marginally increased, to 1.6–1.7, can yield more than twice as high RL. It was envisaged that high RL in a yellow road marking could be achieved if a structure with high vertical profile were reflectorised with these premium glass beads. Because of strict compositional requirements for road markings used in North America, a demonstration trial was made possible due to a special specification that allowed some departure from the fixed standards, but within new high-level demands related to RL under both dry and wet conditions. The tested material was a thermoplastic mass applied as regular dots that, due to round surface, would facilitate rainwater drainage, thus permitting the glass beads surface to be exposed to deliver adequete RL also under wet conditions. The performance achieved in the field was excellent: after 30 days, RL 894 mcd/m²/lx under dry and 160 mcd/m²/lx under wet conditions were achieved. Moreover, the applied road marking system maintained the required performance for 12 months (RL 774 mcd/m²/lx), while the control failed (RL<100 mcd/m²/lx). The outcome of this demonstration is expanding the knowledge related to this specific type of industrial maintenance coatings and should be of profound interest to road administrators who are searching for improved performance of road marking materials to increase road safety, particularly on major thoroughfares.

Microbiota functional activity biosensors for characterizing nutrient metabolism in vivo.

Methods for measuring gut microbiota biochemical activities in vivo are needed to characterize its functional states in health and disease. To illustrate one approach, an arabinan-containing polysaccharide was isolated from pea fiber, its structure defined, and forward genetic and proteomic analyses used to compare its effects, versus unfractionated pea fiber and sugar beet arabinan, on a human gut bacterial strain consortium in gnotobiotic mice. We produced 'Microbiota Functional Activity Biosensors' (MFABs) consisting of glycans covalently linked to the surface of fluorescent paramagnetic microscopic glass beads. Three MFABs, each containing a unique glycan/fluorophore combination, were simultaneously orally gavaged into gnotobiotic mice, recovered from their intestines, and analyzed to directly quantify bacterial metabolism of structurally distinct arabinans in different human diet contexts. Colocalizing pea-fiber arabinan and another polysaccharide (glucomannan) on the bead surface enhanced in vivo degradation of glucomannan. MFABs represent a potentially versatile platform for developing new prebiotics and more nutritious foods.

Column flotation of fine glass beads enhanced by their prior heteroaggregation with microbubbles

The application of microbubbles as flotation carriers in fine minerals beneficiation processes can be a promising approach for solving challenges of fine particles flotation. This study explores the efficiency of column flotation of fine glass beads (ballotini). In test runs ballotini were first mixed with the air-in-water dispersion in CTAB (cetyltrimethylammonium bromide) solution, and then they were fed into a flotation column via a tubular flotation reactor. Independent of the total concentration of the collector in a flotation reactor and a column, the maximum increased recovery is achieved when a volume dosage of microbubbles per floated particles weight unit is 0.3 mL/g. The paper also offers the theoretical substantiation for this effect. The findings have shown that the average shear rate in a flotation reactor significantly influence the dependence of recovery on treatment time. It is suggested that the best performance can be achieved in flotation reactors, which generate shear rates in the range 300–500 s−1, and the treatment time amounts to 8–10 s. These conditions facilitate formation of hetero-aggregates comprising particles and microbubbles, and the size of the aggregates reaches several millimeters. In the test runs with the tubular flotation reactor of 6 mm in diameter at the shear rate of 500 s−1 and treatment time of 8 s, the recovery rate of ballotini increased from 63.2% to 77.6%. It was shown that the effectiveness of treating the mixture of particles and microbubbles in the flotation reactor significantly depends on the method of CTAB collector feed. The best results were achieved when the total amount of collector was fed into the flotation reactor with the microbubble dispersion in the concentrated solution of CTAB collector. In this case, the adsorption of CTAB cations on the microbubble surface caused the positive charging of the surface. As the surface of glass beads initially has a negative charge, the delivery of positively charged microbubbles into the feed creates favorable conditions for forming coarse hetero-aggregates due to Coulomb attraction of particles and microbubbles.

Adsorption of nanoparticles on glass bead surface for enhancing proppant performance: A systematic experimental study

Effective coating of nanoparticles on the proppant pack has been regarded as a promising technique for enhancing proppant functions to achieve multiple objectives. In this work, a dynamic soaking technique which we refer as “pseudo-continuous fixed bed (PCFB)” adsorption has been employed for the first time for coating of four bare NPs (Al2O3, SiO2, MgO, ZrO2) with divergent physical and chemical properties, onto a fixed adsorbent glass bead proppant pack. A systematic study of the formulated nanofluid (brine+NPs) adsorption onto the proppant pack was conducted vis-à-vis salinity (0 to 10.5 wt% NaCl), temperature (298.15 to 348.15 K), NPs loading (0.01 to 0.2 wt%), and injection rates (1 to 50 mL.min−1). Nanofluid stability was measured via zeta-potential measurements, where NP adsorption was verified through optical microscopy and atomic force microscopy. Results show that PCFB adsorption of NPs with higher specific surface area resulted in faster adsorption (adsorbed in ~25 mins) with >99% immobilisation of NPs on the proppant pack. Adsorption kinetics showed reasonable conformity with the pseudo-first-order model, where isothermal adsorption followed a Sips model. The adsorption capacity of MgO NPs (specific surface area 50–80 m2.g−1, 7.0 wt% NaCl) at 298.15 K was found to be the highest when compared with silica NPs. Accordingly, this method can be used for onsite treatment of proppants with nanoparticles, which can then be injected into a fractured formation to achieve multiple objectives.

The quest for reusability: The facile and stable immobilization of papain on cysteine functionalized iron oxide nanoparticles activated glass surface

The study displays the immobilization of papain on cysteine functionalized iron oxide nanoparticle coated glass beads. Glass beads were treated with (3-mercaptopropyl) trimethoxysilane and iron oxide nanoparticles capped with cysteine, to create a layer of cysteine on the surface of glass bead. This functionalized glass bead surface was further used to immobilize papain through glutaraldehyde treatment. The average size of cysteine capped iron oxide nanoparticles were found to be 50 nm. The binding of cysteine through the iron oxide nanoparticles was validated by Fourier transform infra-red spectroscopy. The activity of enzyme was found to be stable at variable temperature and pH conditions. The covalently immobilized enzyme on the glass bead sustained high enzyme activity and could be reused for 5 times without losing its activity. The immobilized papain retained 81% of its initial activity after 5 consecutive cycle. The storage stability analysis of the immobilized system revealed that it is stable for 6 months without loss in its activity. An average of 1.8 mg papain was successfully immobilized per gram of glass beads. In this case cysteine emerges as a new and effective medium for immobilizing biomolecules as it provides high efficiency towards immobilization.

Determining the impact of biofilm in the bioaugmentation process of benzene-contaminated resources

Recently, petroleum contamination in groundwater has become one of the most common environmental problems. Bioaugmentation is proposed as a fully functional and economical technology by the addition of microorganisms to remove pollutants. The aim was to study the effect of biofilm formation of different species during the bioaugmentation of benzene removal in a Permeable Reactive Barrier (PRB) system based on calcium peroxide (CaO2) nanoparticles. Therefore, at first 3 strains identified with the ability to form biofilms and benzene degradation were isolated from groundwater. Subsequently, dissolved oxygen (DO), pH, the concentration of benzene, and microbial count of experimental columns were measured. Further, the examination of the biofilm formation on glass bead surfaces in bioaugmented and control reactors was also studied by confocal laser scanning microscopy (CLSM). The results of bioaugmentation show that adding Pseudomonas lini and Pseudarthrobacter polychromogenes can remove almost 80% of benzene from effluent after 70 days. Therefore, the study reveals the effect of bioaugmentation over intrinsic bioremediation. Also, the thicker and concentrated biofilm of Pseudomonas lini can be seen. This system provides a novel environmentally friendly technology for the in situ bioremediation of benzene.

Effects of operational parameters on bacterial inactivation in Vis-LEDs illuminated N-doped TiO2 based photoreactor

Titanium dioxide (TiO2) based photocatalysis has been widely investigated for several applications in the past. The major challenges related to this catalyst have also been successfully tackled through doping and immobilization techniques. For the practical application of the TiO2 photocatalyst in environmental remediation, the selection and design of proper types of photoreactors are also mandatory. The present study focuses on the investigation of operational parameters of a new type of Vis-LEDs illuminated N-doped TiO2 based photoreactor developed from immobilized visible light active nitrogen-doped titanium dioxide on the surface of glass beads. Advanced instruments, such as HR-TEM, XRD, BET, XPS, UV-Vis, FE-SEM, FT-IR, and TGA-DSC were employed to characterize the prepared catalyst. The performance of the photoreactor has also been investigated under different operational parameters (such as TiO2 load, initial E. coli concentration, bacterial solution feed flow rate, and light incident photon flux). Results showed that the inactivation efficiency of the reactor was found to increase with increasing TiO2 load and incident photon flux. However, the efficiency of the reactor decreased with increasing E. coli concentration and bacterial solution flow rate. The results indicate that initial E. coli concentration of 106 CFU mL-1, TiO2 concentration of 0.6 g, a flow rate of 40 mL min-1 and light incident photon flux of 5.23 × 1016 photons/s demonstrated higher inactivation efficiency in comparison to other study parameters. The photocatalytic inactivation kinetics also best fitted to Modified-Hom model with R2 0.9998.