Hybrid Beads Research Articles

점토광물과 키토산 hybrid bead를 이용한 호소의 영양염류 및 녹조 제거

점토광물과 키토산 hybrid bead를 이용한 호소의 영양염류 및 녹조 제거

타닌과 키토산 하이브리드 비드를 이용한 수용액의 Pb(II) 제거

타닌과 키토산 하이브리드 비드를 이용한 수용액의 Pb(II) 제거

Improved stability and catalytic activity of graphene oxide/chitosan hybrid beads loaded with porcine liver esterase

ABSTRACTGraphene oxide/chitosan and reduced graphene oxide/chitosan (GO/CS and RGO/CS) beads were prepared by precipitation with NaOH. Porcine liver esterase was immobilized on these beads to give GO/CS/E and RGO/CS/E beads. The optimum conditions for the maximum activity of RGO/CS/E beads were pH 8 and 50°C. The stability of the enzyme immobilized on GO/CS/E and RGO/CS/E was high in the pH range of 5–8. The GO/CS/E beads showed superior stability compared to that of the free enzyme and CS/E beads between 20 and 50°C. Kinetic analysis showed that GO/CS/E was a better catalyst than the RGO/CS/E beads with a lower Km value of 0.9 mM. The hybrid beads also retained more than 95% activity after 10 consecutive cycles. The GO/CS/E and RGO/CS/E beads retained 84% and 87% activity after 40 days at 4°C. The GO/CS/E beads were used for the successful hydrolysis of methyl 4-hydroxy benzoate.

N- and O- ligand doped mesoporous silica-chitosan hybrid beads for the efficient, sustainable and selective recovery of rare earth elements (REE) from acid mine drainage (AMD): Understanding the significance of physical modification and conditioning of the polymer

Silica-chitosan hybrid beads were synthesized via three different methods to investigate the selective recovery of REE from AMD. The influence of amino/non-amino silanes, high molecular weight/high viscous chitosan and N-/O- based ligands were studied and their effects on REE removal efficiencies were analyzed. The adsorption efficiencies of three various groups of modified beads were inspected with respect to feed pH, in a single and a multi-component system, and their affinities towards the light and heavy rare earth elements (LREE/ HREEs) were interpreted to understand the intra-series REE separation behavior. The focus of the study was mainly directed towards utilizing these fabricated beads for the recovery of valuable REEs from the real AMD obtained at three different sampling depths which was found rich in iron, sulfur and aluminum. Moreover, the selectivity of the beads towards REEs improved with silanized and ligand immobilized gels and their impacts on REE recovery in the presence of competing ions were successfully presented in this paper. Also, the synthesized beads showed rapid REE adsorption and recovery within a process time of 5 min. Group II adsorbents, synthesized by forming silica-chitosan hybrid beads followed by PAN/acac modifications, showed superiority over the other groups of adsorbents.

Hydrothermal assisted magnetic nano-hydroxyapatite encapsulated alginate beads for efficient Cr(VI) uptake from water

The biopolymer, alginate can be made into various usable forms like beads, membrane and candle for the development of water technology. In the present study, an attempt has been made to prepare the alginate in an usable bead form. Here, magnetic nano-hydroxyapatite encapsulated alginate beads (Fe3O4@n-HApAlg) were synthesized by hydrothermal method for selective chromium removal. The synthesized Fe3O4@n-HApAlg beads have enhanced chromium sorptive capacity (SC) of 29.14 mg/g than the individual components. The synthesized materials were characterized by various instrumental techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) isotherm studies. The Cr(VI) sorptive mechanism of Fe3O4@n-HApAlg beads were interpreted by electrostatic attraction. Sorption behavior of the magnetic beads was explained using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. The thermodynamic studies indicate the spontaneous and endothermic nature of Cr(VI) sorption. In the kinetic data demonstration, pseudo-first-order, pseudo-second-order, intra particle diffusion and particle diffusion models were employed. The reusability of Fe3O4@n-HApAlg beads was carried out using NaOH eluent and they can be used upto five cycles. The magnetic alginate hybrid beads showed the promising results against the chromium contaminated groundwater by removing Cr(VI) ions below the tolerance limit.

Development and Reuse of Amine-Grafted Chitosan Hybrid Beads in the Retention of Nitrate and Phosphate

A variety of adsorbent materials have been tried day by day to minimize the effects of blue baby syndrome and eutrophication but most of them constitute academic interest because of their properties such as powder form, poor selectivity, not easily separable, and difficult regeneration; hence, they could not be used at field conditions. To overcome such technological bottle-necks, the present study has been carried out with amine-functionalized magnetic chitosan (AFMCS) composite beads which was prepared and applied for the remediation of nitrate and phosphate in batch scale. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis with mapping analysis. The numerous adsorption-influenced parameters such as contact time, adsorbent dosage, initial ions concentration, co-anions, solution pH, and temperature were opti...

Immobilization of laccase onto porous polyvinyl alcohol/halloysite hybrid beads for dye removal.

Laccase was immobilized in polyvinyl alcohol beads containing halloysite nanotubes (PVA/HNTs) to improve the stability and reusability of enzyme. The porous structure of PVA/HNTs beads facilitates the entrapment of enzyme and prevents the leaching of immobilized laccase as well. Halloysite nanotubes act as bridge to connect the adjacent pores, facilitating the electron transfer and enhancing the mechanical properties. PVA/HNTs beads have high laccase immobilization capacity (237.02 mg/g) and activity recovery yield (79.15%), indicating it can be used as potential support for laccase immobilization. Compared with free laccase, the immobilized laccase on hybrid beads exhibits enhanced pH tolerance (even at pH 8.0), good thermal stability (57.5% of the initial activity can be maintained at 75 °C), and excellent storage stability (81.17% of enzyme activity could be retained after storage at 4 °C for 5 weeks compared with that for free enzyme of 60%). Also, the removal efficiency for reactive blue can reach as high as 93.41% in the presence of redox mediator 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonate), in which adsorption and degradation exist simultaneously. The remarkable pH tolerance, thermal and storage stability, and reuse ability imply potential application of porous PVA/HNTs immobilized enzyme in environmental fields.

Sorption studies of heavy metal ions on pectin-nano-titanium dioxide composite adsorbent

ABSTRACTThe Cu(II), Cd(II), Zn(II), and Pb(II) sorption kinetics and equilibrium on hybrid material, composed of pectin and titanium dioxide nanopowder, were examined. Parameters, such as pH and adsorbent dose, were also investigated. The experimental data were better described by the Langmuir model. The maximum adsorption capacities were 1.37, 0.68, 0.51, and 0.83 mmol/g for Cu(II), Cd(II), Zn(II), and Pb(II), respectively. The introduction of nano-TiO2 improved the kinetics of the metal ion sorption. The titanium dioxide, despite its small content (6%), contributes to the removal of the examined metal ions and eventually to the adsorption capacity of hybrid beads.

Alginate Microcapsules Incorporating Hyaluronic Acid Recreate Closer in Vivo Environment for Mesenchymal Stem Cells.

The potential clinical application of alginate cell microencapsulation has advanced enormously during the past decade. However, the 3D environment created by alginate beads does not mimic the natural extracellular matrix surrounding cells in vivo, responsible of cell survival and functionality. As one of the most frequent macromolecules present in the extracellular matrix is hyaluronic acid, we have formed hybrid beads with alginate and hyaluronic acid recreating a closer in vivo cell environment. Our results show that 1% alginate-0.25% hyaluronic acid microcapsules retain 1.5% alginate physicochemical properties. Moreover, mesenchymal stem cells encapsulated in these hybrid beads show enhanced viability therapeutic protein release and mesenchymal stem cells' potential to differentiate into chondrogenic lineage. Although future studies with additional proteins need to be done in order to approach even more the extracellular matrix features, we have shown that hyaluronic acid protects alginate encapsulated mesenchymal stem cells by providing a niche-like environment and remaining them competent as a sustainable drug delivery system.

Removal of p-chlorophenol from aqueous solutions by carbon nanotube hybrid polymer adsorbents

Aiming to remove chlorophenols from aqueous solution, carbon nanotube (CNT) hybrid polymer beads were fabricated via the phase inversion method, and were adopted as adsorbents to remove p-chlorophenol in this study. The CNT hybrid bead was composed of a smooth outer surface and hierarchical porous inner structure, with worm-like CNTs lying on/embedded in the polymer slices. The incorporation of CNTs in the polymer beads resulted in a dramatically improvement of the surface area. The adsorption kinetics and isotherms of p-chlorophenol from aqueous solutions on CNT hybrid adsorbents were studied, and the impacts of temperature and pH value on the adsorption were also explored. The adsorption capacity of CNT hybrid adsorbents towards p-chlorophenol was significantly superior to that of the neat polymer adsorbent and pristine CNT. And the CNT hybrid adsorbents also showed an outstanding separation performance from water treatment system after adsorption. The adsorption process of p-chlorophenol on CNT hybrid adsorbents was found to be an exothermic process, and physical adsorption was the predominant mechanism. The neutral p-chlorophenol molecule was a more effective form for adsorption than was the ionic form. The interaction between p-chlorophenol and the CNT hybrid adsorbents responsible for the adsorption was assumed mainly non-polar forces such as hydrophobic interactions and π–π electron coupling.

Macroporous alginate/ferrihydrite hybrid beads used to remove anionic dye in batch and fixed-bed reactors

Abstract Two-line ferrihydrite was prepared by neutralizing Fe(III) and then characterized by means of various methods, including X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) theory and zetametry. The alginate/ferrihydrite hybrid beads with various porosities, as synthesized through an entrapment process, were used as an adsorbent for the removal of anionic dye methyl orange (MO). The kinetic and isotherm results were best described by pseudo second-order models and Langmuir models, respectively. An effective diffusion coefficient was calculated for the beads according to the procedure offered by Reichenberg. These results showed that porosity improves the diffusion coefficient of MO as well as the MO sorption capacity. The hybrid beads were further investigated in dynamic system sorption; the effects of operating conditions, such as flow rates and initial MO concentration, have also been studied. The Thomas model displayed a good fit with the experimental results. The results proved that the creation of macroporosity improves the sorption amount in fixed-bed reactor. The better column sorption is characterized by a higher MO concentration but with a lower feed flow rate.

Monolithic Cu/C hybrid beads with well-developed porosity for the reduction of 4-nitrophenol to 4-aminophenol

Cu/C hybrid beads with well-developed porosity, offering potential advantages of low cost, an environmentally friendly fabrication process, easy processing and durable activity, were successfully fabricated.

Solvent-free synthesis of the cellulose-based hybrid beads for adsorption of lead ions in aqueous solutions

Modified cellulose hybrid beads were synthesised as absorbents for Pb2+removal and CaCO3was utilized to increase pore structure.

Development of organic–inorganic hybrid beads from sepiolite and cellulose for effective adsorption of malachite green

A facile approach has been developed to fabricate well defined organic–inorganic hybrid beads from widely available bamboo pulp and sepiolite, in expectation of an alternative green adsorbent for the removal of organic dyes.

Preparation and Biochemical Property of Penicillin G Amidase-Loaded Alginate and Alginate/Chitosan Hydrogel Beads.

Penicillin G amidase (PGA) (EC 3.5.1.11) are enzymes that are mainly involved in the synthesis of semi-synthetic }-lactam antibiotics. Soluble PGA is costly and lacks long term operational stability. We revised most of the patents related to Penicillin G amidase (PGA) immobilization in the section "Recent Patents on Immobilized Penicillin G Amidase". The aim of this work was to study comparative biochemical property of PGA enzyme immobilized in two hydro-gel beads - Ca-alginate and alginate+chitosan hybrid and morphologically characterised by SEM. PGA immobilized in alginate+chitosan hybrid bead shows high pH and thermal stability. Km, Vmax and Effectiveness factor (1) value of free PGA were 56.19 mg/ml, 1.786 U/ml and 1, respectively. These parameters for PGA immobilized alginate beads were 64.84 mg/ml, 0.781U/ml and 0.437, respectively and for PGA immobilized alginate+chitosan hybrid beads were 87.08 mg/ml, 0.622 U/ml and 0.348, respectively. Immobilized PGA on alginate+chitosan hybrid beads gave the highest thermal stability, reusability and storage stability than alginate immobilized PGA. The entrapment of PGA on alginate+chitosan hybrid beads revealed several advantages and could be used in 6APA (6- aminopenicillanic acid) production.

Robust and Biocompatible Hybrid Matrix with Controllable Permeability for Microalgae Encapsulation.

Hybrid beads with entrapped microalgae Chlamydomonas reinhardtii were synthesized for the sustainable production of high value metabolites via photosynthesis. Encapsulating the microalgae requires an exquisite control of material properties, which has been achieved by modifying the composition (alginate, polycation, and silica). A coating of PDADMAC precluded cell leakage as indicated by the OD750 value of the culture medium, and the homogeneous distribution of silica prevented bead shrinkage from the strong electronic force of PDADMAC, resulting in a robust and biocompatible matrix for the cells. Besides fabricating suitable porous beads for the diffusion of expected metabolites, the permeability can be controlled to a certain degree by applying different molecular weights of PDADMAC. The hybrid alginate+silica/CaCl2+PDADMAC beads possessed sufficient mechanical rigidity to sheer force under constant stirring and good chemical stability to chelating agents such as sodium citrate. Moreover, the encapsulated cells exhibited excellent long-term viability and cellular functionality, which retained about 81.5% of the original value after a 120 day encapsulation as observed by microscopy and oximetry measurement. This study is not only significant for understanding the critical role of polycations and silica involved in the synthesis of hybrid beads but also important for real-scale bioengineering applications.

Alginate/magnetite hybrid beads for magnetically stimulated release of dopamine

Hybrid beads composed of magnetite nanoparticles (MNP) and alginate (Alg) were synthesized and coded as Alg-MNP. They were incubated in dopamine (DOPA) solution (5g/L), at pH 7.4 and 8°C, during 12h, promoting the DOPA loaded magnetic beads, coded as Alg-MNP/DOPA. The release of DOPA was further evaluated in the absence and the presence of external magnetic field (EMF) of 0.4T. The products Alg-MNP and Alg-MNP/DOPA were characterized by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared vibrational spectroscopy (FTIR), UV spectrophotometry, thermogravimetric analyses (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses and superconducting quantum interference device (SQUID) magnetometer. The magnetic and chemical properties of Alg-MNP beads were not affected by DOPA loading. The incorporation of DOPA into the beads depended on the pH and on the negative charge density. At pH 7.4 38% of DOPA were loaded into Alg-MNP beads, whereas at pH 2 or using neat Alg beads (lower charge density than Alg-MNP) the loading efficiency decreased to one third or less. In the absence of EMF, 24% of the loaded DOPA was released from Alg-MNP at pH 7.4 over a period of 26h. The released amount increased to 33% under the stimulus of EMF. A model was proposed to explain the loading efficiency of charged drugs, as DOPA, into hybrid beads and the role played by EMF on delivery systems, where drug and matrix are oppositely charged. The results suggest that the alginate combined with magnetite nanoparticles is a promising system for release of DOPA in the presence of EMF.

Visible Light-Triggered On-Demand Drug Release from Hybrid Hydrogels and its Application in Transdermal Patches.

On-demand release from stimuli-responsive hydrogels has received great attention due to an increasing clinical need. Here, we have prepared spherical hydrogel beads showing visible light-induced volume change at body temper-ature. By spray injection of the monomer solution using the alginate templ-ating method, hybrid beads of several hundred micrometers, consisting of temperature-responsive poly(N-isopropylacrylamide-co-vinyl-2-pyrrolidinone) hydrogel and magnetite nanoparticles (MNP), are produced. MNP dispersed in the hydrogel matrix absorbed visible light and generated heat, increasing the temperature of the matrix and resulting in shrinkage of the beads proportional to light intensity. It is demonstrated that light-induced volume change of dexamethasone-loaded hybrid beads result in on-demand and localized release of the drug by exposure to moderate visible light. As a potential application of the light-sensitive hybrid hydrogel beads, a transdermal patch is developed that incorporates drug-loaded hydrogel beads in multiple drug reservoirs, achieving enhanced release of a model drug when exposed to visible light. This platform should be applicable to on-demand, sequential, and long-term release of drugs via light exposure.

Hg(II) Adsorption By Alginate-guar Gum Templated Titania Spheres: Kinetic And Isotherm Studies

In present communication we report on the kinetic and isotherm studies on Hg(II) removal using our recently reported material, the millimeter sized hollow titania spheres (TSP). The mesoporous spheres with high surface area (11.75 m 2 /g) and bimodal pore size distribution were fabricated by a facile sol-gel approach using alginate-guar gum hybrid beads as the structure directing agent. In order to investigate the utility of TSP for Hg(II) adsorption, the batch adsorption experiments were conducted at various pH values (2–7), initial Hg(II) concentrations (50–300 mg/L), and TSP doses (20-100 mg) at 150 rpm, and 30 °C temperature. The spheres exhibited good capacity to adsorb Hg(II) in wide pH range (pH 3 to pH 7). It was possible to remove >95 % Hg(II) from 100 mg/L synthetic Hg(II) solution at pH 5, and 50 mg TSP dose in 10 h. The adsorption equilibrium data were better fitted to Langmuir model at low temperatures while Freundlich model become favored as the temperature was increased to 40 ºC. Langmuir adsorption isotherm study indicated that the monolayer adsorption capacity of TSP was 62.5 mg/g 62.5 mg/g 78.7 mg/g and 100 mg/g at 10, 20, 30, and 40 ºC respectively, which suggested good Hg(II) adsorption capacity of TSP. The calculated RL values evidenced the feasibility of the adsorption. Adsorption kinetic data well accorded with pseudo-second order kinetic model with the rate constant k, equal to 2.5 x 10 -4 g/mg.min 1.99 x 10 -4 g/mg.min and 0.28 x 10 -4 g/mg.min at 100, 150 and 200 mg/mL initial Hg (II) concentrations, indicating chemisorption taking place in the rate determining step. At high initial Hg(II) concentration (200 mg/mL), the adsorption was exclusively controlled by intraparticle diffusion. The study revealed the suitability of TSP for the mercury removal from wastewater.

Highly efficient, long life, reusable and robust photosynthetic hybrid core–shell beads for the sustainable production of high value compounds

An efficient one-step process to synthesize highly porous (Ca-alginate–SiO2–polycation) shell: (Na-alginate–SiO2) core hybrid beads for cell encapsulation, yielding a reusable long-life photosynthetically active material for a sustainable manufacture of high-value metabolites is presented. Bead formation is based on crosslinking of an alginate biopolymer and mineralisation of silicic acid in combination with a coacervation process between a polycation and the silica sol, forming a semi-permeable external membrane. The excellent mechanical strength and durability of the monodispersed beads and the control of their porosity and textural properties is achieved by tailoring the silica and alginate loading, polycation concentration and incubation time during coacervation. This process has led to the formation of a remarkably robust hybrid material that confers exceptional protection to live cells against sheer stresses and contamination in a diverse range of applications. Dunaliella tertiolecta encapsulated within this hybrid core–shell system display high photosynthetic activity over a long duration (>1year). This sustainable biotechnology could find use in high value chemical harvests and biofuel cells to photosynthetic solar cells (energy transformation, electricity production, water splitting technologies). Furthermore the material can be engineered into various forms from spheres to variable thickness films, broadening its potential applications.