Gel Beads Research Articles

Study on the removal of Pb(II) from water by coated sulfur-modified nanoscale zero-valent iron.

Being prepared by a liquid-phase reduction method, sulfur-modified nanoscale zero-valent iron (S-nZVI) was then coated with sodium alginate (SA) to form gel beads (SAS-nZVI) which are capable of removing Pb(II) from water. SAS-nZVI was characterized by SEM, EDS, FTIR, XRD, and BET, and its removal effect on Pb(II) in water, including the effects of pH, adsorbent dosage, shaking time, and initial concentration of lead, was also studied. The results demonstrated that the maximum removal efficiency of Pb(II) by SAS-nZVI was 97.89%, and the maximum uptake was 246.40 mg/g. In the Pb(II) removal behavior study, the pseudo-second-order kinetic model and the Langmuir isotherm model were found to fit the adsorption process well. SAS-nZVI was easier to recycle from the reaction system, and the removal efficiency of SAS-nZVI to Pb(II) in water was still able to reach 82.75% after five cycles. Therefore, this study suggests that SAS-nZVI has a high removal capacity for Pb(II) and great potential in water pollution treatment.

Adsorption of emerging contaminants by graphene related materials and their alginate composite hydrogels

Graphene nanosheets and nanoplatelets -alginate composite hydrogels were prepared by ionic gelation and the resulting gel beads were exploited for the removal of a mixture of eight selected emerging contaminants (ECs) in tap water, including bisphenol A, ofloxacin and diclofenac. The role of graphene related materials (GRM) on the gel bead structure, adsorption selectivity, kinetic, mechanism, and efficiency was investigated. Combined Scanning Electron Microscopy (SEM) and confocal Raman microscopy mapping showed a porous structure with pore size in the range of 100–200 µm and a homogeneous distribution of graphene nanosheets or nanoplatelets at the pores surface. The adsorption kinetic of GRM was much faster than that of granular activated carbon (GAC), the industrial sorbent benchmark, with removal capacity of ofloxacin from 2.9 to 4.3 times higher. A maximum adsorption capacity of 178 mg/g for rhodamine B was estimated by adsorption isotherm studies for reduced graphene oxide-based beads (a value comparable to that of powered activated carbon). Regeneration test performed on saturated beads by washing with EtOH, and subsequent reiterated reuses, showed no loss of adsorption performance up to the fourth reuse cycle.

Immobilization of protease on chitosan–silica gel beads for high detergent and surfactant stability and high tolerance against metallic ions and organic solvents

Immobilization of protease on chitosan–silica gel beads for high detergent and surfactant stability and high tolerance against metallic ions and organic solvents

Isolation, purification, and metal-induced gelation of released polysaccharides from spent culture medium of Arthrospira

Cyanobacteria release polysaccharides that accumulate in the culture medium. In this study, released polysaccharides were isolated from the spent culture medium of an Arthrospira farm with a carbohydrate concentration of 136 mg L−1. The polysaccharides were concentrated 5.2 times by ultrafiltration using a 50 kDa polysulphone membrane and purified (desalting, protein removal). The polysaccharides were rich in uronic acid (159 mg g−1), had a low sulfate content (2.3 mg g−1), and contained 9 different monosaccharides, with 2-deoxy-d-galactose (27.9 %), fucose (22.7 %), glucose (22.0 %), and glucuronic acid (17.1 %) being dominant. A 1 % w/v polysaccharide concentrate formed stable gel beads in Al3+ and Fe3+ solutions. Rheological characterization of the gel revealed stable storage (G' = 38 Pa) and loss modulus (G" = 6 Pa) over a wide frequency range. This study demonstrates the feasibility to recover polysaccharides from Arthrospira spent culture medium and the potential to use these polysaccharides in food or biotechnological applications.

Monascus Yellow Pigment Production by Coupled Immobilized-Cell Fermentation and Extractive Fermentation in Nonionic Surfactant Micelle Aqueous Solution

Microbial fermentation with immobilized cells possesses many advantages. However, this fermentation mode is restricted to the production of extracellular products. Our previous study demonstrated that the extractive fermentation of Monascus spp. in nonionic surfactant micelle aqueous solution can export Monascus pigments that are supposed to be mainly intracellular products to extracellular culture broth and, in the meantime, extracellularly enhance the production of yellow pigments at a low pH condition; consequently, this makes the continuous production of yellow pigments with immobilized Monascus cells feasible. In this study, immobilized-cell fermentation and extractive fermentation in Triton X-100 micelle aqueous solution were successfully combined to continuously produce Monascus yellow pigments extracellularly. We examined the effects of cell immobilization and Triton X-100 on cell growth, pigment production, and pigment composition. In the repeated-batch extractive fermentation with immobilized cells, the biomass in Ca-alginate gel beads continued to grow and reached 21.2 g/L after seven batches, and dominant yellow pigments were produced extracellularly and stable for each batch. The mean productivity of the extracellular yellow pigments reached up to 22.31 AU410 nm/day within the first four batches (13 days) and 19.7 AU410 nm/day within the first seven batches (25 days). The results also provide a new strategy for producing such intracellular products continuously and extracellularly.

Effect of Potassium Peroxodisulphate and Microwave Power on Hydrogel Character Based on Banana Peel Waste Using Microwave Grafting Method

<p><em>Musa paradisiaca var. raja</em> peel waste contains cellulose which has the potential to be a raw material for synthesizing hydrogels. This research utilizes acrylamide monomer grafted onto banana peel cellulose backbone using the microwave grafting method to produce hydrogel. The banana peel waste was dried to a constant weight and then crushed into powder. Banana peel powder was through a delignification process with the addition of NaOH and bleached with NaClO to took only the cellulose of the banana peel. The mixture of banana peel cellulose-acrylamide-potassium peroxodisulfate powder through the grafting process was repeated with variations in KPS concentration and microwave power. The reaction was terminated with a hydroquinone solution, washed with acetone, and then precipitated. The precipitated solid was dried to a powder called cellulose-g-PAAM. A homogeneous solution of 2% carrageenan-cellulose-g-PAAM underwent a physical crosslinking process using KCl and CaCl<sub>2</sub> solutions after passing through palm oil to form a bead gel. The purpose of this research was to determine the effect of potassium peroxodisulfate (KPS) initiator concentration and microwave power on the swelling capacity in water. The properties of obtained dried bead gels were characterized their functional groups using FTIR and swelling capacity test in water. From this research, it can be concluded that banana peel cellulose was successfully grafted onto acrylamide monomer as evidenced by the FTIR test results. The lower KPS concentration is the greater on the swelling capacity and the microwave power has no effect on the swelling capacity of bead gels.</p><p><strong>Keywords: </strong>Banana peel, Bead gel, Microwave, Swelling degree </p>

Development and validation of novel automatable assay for cholesterol efflux capacity.

During the past decade, evaluation of high-density lipoprotein (HDL) functionality has been well studied for predicting cardiovascular disease risk. Cholesterol efflux capacity (CEC) is the strongest candidate as the biomarker out of various HDL anti-atherosclerotic functions. However, CEC has not yet been introduced clinically because of several technical issues, including the use of radioactive materials and differentiated cells in the assay. Previously, our laboratory developed a radioisotope- and cell-free CEC assay called the immobilized liposome-bound gel beads (ILGs) method to replace the conventional method. However, the separation process of the supernatant was not suitable for installation in an automatic analyzer. This study aims to develop a new method that is easier to operate. We assumed that the use of magnetic beads instead of gel beads would enable the skip of the centrifugal process. First, similar to the ILG method, porous magnetic beads were treated with liposomes containing fluorescently labeled cholesterol. Fluorescence was observed inside the magnetic beads, and almost the same amount of liposomes as in the ILG method was immobilized successfully. These immobilized liposome-bound magnetic beads (ILMs) were available for CEC assay when HDL and apolipoprotein B-100 depleted serum were used as cholesterol acceptors. The ILM method showed sufficient basic performance and a good correlation with the ILG method. Furthermore, when the CEC of 15 serum samples from healthy subjects was measured, a good correlation between HDL-cholesterol level and the ILG method was confirmed. Thus, it was confirmed that the ILM method was successfully developed and could be automated.

Influence of high hydrostatic pressure on protein clustering: Implications for processing and macroscopic crystallization.

High pressure (HP) is used in various industrial applications to sterilize a product stream or to confer desired properties. HP is also present during freezing processes, yet relatively little is known about its effects on protein phases. Protein clustering has been well-documented as a precursor to liquid-liquid phase separation (LLPS) and macroscopic crystallization. Several globular proteins have been previously shown to salt-out in the presence of ammonium sulfate, with clustering observed when approaching a first aggregation boundary, phase separation beyond a second aggregation boundary, and gel bead nucleation between them. Nanocrystalline structures have been observed within the salted-out macroscopic gels, suggesting clusters below the first aggregation boundary are precursors to macroscopic crystals. The present work examines the influence of pressures up to 400 MPa on salt-induced clustering in ovalbumin solutions on either side of the first aggregation boundary. Small-angle x-ray scattering (SAXS) on aged solutions approaching the boundary reveals the presence of protein clusters, and a computational deconvolution into fractional oligomer population contributions to scattering was used to assess salt-induced clustering with similar characteristics on either side of the first aggregation boundary. Surprisingly, HP-SAXS on fresh samples reveals a sharp shift in pressure effects on clustering across the boundary. The discrepancy in pressure response suggests a fundamental difference in the clustering mechanism across the first aggregation boundary, and that clusters in this region are early nucleated gels rather than crystal precursors. The current results are of interest to protein processing and LLPS, providing insights into competing mechanisms of protein aggregation and suggesting pressure-dictated clustering as a potential tool for controlling macroscopic phase behavior.

Preparation and rheology of titanium dioxide nanoparticles loaded κ‐carrageenan hydrogel beads strengthened by mixed salts for multipollutant water remediation

AbstractHydrogel beads are emerging as alternate adsorbent material for the batch or continuous column treatment of dye wastewater. Polysaccharide‐based gel beads are preferred for their uniform shape and size, large specific surface area, and easy separation by filtration and subsequent reuse. In this work, we prepare and rheologically characterize UV‐active κ‐carrageenan/TiO2 beads for the adsorption and degradation of dyes. The 3–4 mm sized nanocomposite beads are formed by the extrusion of κ‐carrageenan/TiO2 gel solution in salt solutions. The maximum increase in modulus was observed with the addition of 1% w/v TiO2 to κ‐carrageenan and subsequent crosslinking with mixed salt of KCl and CaCl2. κ‐carrageenan/TiO2 beads crosslinked by mixed salt of KCl and CaCl2 have higher adsorption capacity, as compared to beads crosslinked with single salt of KCl. The kinetic study indicated the chemisorption of Methylene Blue on the bead surface. κ‐carrageenan/TiO2 beads showed higher degradation for Methylene Blue and Nile Blue A than Rhodamine B in 5 and 50 ppm each multicomponent dye systems under UV irradiation. The κ‐carrageenan/TiO2 beads could form a porous column for the selective adsorption of positively charged dyes from a multicomponent dye system.

Mechanically Robust Hybrid Gel Beads Loaded with "Naked" Palladium Nanoparticles as Efficient, Reusable, and Sustainable Catalysts for the Suzuki-Miyaura Reaction.

The increase in demand for Pd and its low abundance pose a significant threat to its future availability, rendering research into more sustainable Pd-based technologies essential. Herein, we report Pd scavenging mechanically robust hybrid gel beads composed of agarose, a polymer gelator (PG), and an active low-molecular-weight gelator (LMWG) based on 1,3:2,4-dibenzylidenesorbitol (DBS), DBS-CONHNH 2 . The robustness of the PG and the ability of the LMWG to reduce Pd(II) in situ to generate naked Pd(0) nanoparticles (PdNPs) combine within these gel beads to give them potential as practical catalysts for Suzuki-Miyaura cross-coupling reactions. The optimized gel beads demonstrate good reusability, green metrics, and most importantly the ability to sustain stirring, improving reaction times and energy consumption compared to previous examples. In contrast to previous reports, the leaching of palladium from these next-generation beads is almost completely eliminated. Additionally, for the first time, a detailed investigation of these Pd-loaded gel beads explains precisely how the nanoparticles are formed in situ without a stabilizing ligand. Further, detailed catalytic investigations demonstrate that catalysis occurs within the gel beads. Hence, these beads can essentially be considered as robust "nonligated" heterogeneous PdNP catalysts. Given the challenges in developing ligand-free, naked Pd nanoparticles as stable catalysts, these gel beads may have future potential for the development of easily used systems to perform chemical reactions in "kit" form.

Enhancing mechanical properties of polyvinyl alcohol/sodium alginate gel beads by graphene oxide for the aerobic sludge immobilization in wastewater treatment

This study reinforced polyvinyl alcohol/sodium alginate (PVA/SA) gel beads immobilizing aerobic sludge with graphene oxide (GO) as a nanofiller. The different types of beads were made by various concentrations of GO (0.02, 0.2, 2, 20, and 200 mg/L). The effect of GO on beads structure was observed by comparing the mechanical properties of chemical oxygen demand (COD) and NH<sub>4</sub><sup>+</sup>-N removal efficiencies. The results showed that the PVA/SA/GO gel carriers have excellent reinforcement properties compared to non-GO gel carriers, while sphericity factor and methylene blue absorption are the same. The strongest carrier contains 200 mg/L GO, referred to as GO6. In addition, the highest COD and NH<sub>4</sub><sup>+</sup>-N removal efficiencies of GO6 gel carriers were 97 and 96.67%, respectively, which is higher than a non-GO PVA/SA (GO1) gel carrier. The addition of GO (200 mg/L) was thus an effective way to improve the mechanical strength of PVA/SA gel beads due to the strong interaction between GO and the PVA/SA matrix. It can also promote COD and NH<sub>4</sub><sup>+</sup>-N removal efficiency of immobilized bacteria inside the beads.

Effect of Acrylamide And Potassium Peroxodisulphate on The Quality of Bead Gel Based on Cassava Bagasse-Carrageenan Using Microwave Grafting Method

Hydrogels are widely used for drug delivery systems, immuno-chemotherapy applications, efficient use of water, preventing dry soil, and increasing soil infiltration. Generally, hydrogels are derived from synthetic polymers which is non-biodegradable and toxic. Cassava bagasse is an alternative cellulose to make hydrogels. The purpose of this research was to determine the effect of the amount of acrylamide and potassium peroxodisulphate (KPS) initiator on the quality of bead gel based on cassava bagasse-carrageenan. Chemical structure of the hydrogel was studied using FTIR spectroscopy. Cassava bagasse was immersed in a solution of n-hexane to separate the fat. Then, fat-free cassava bagasse was grafted with mass ratios of cassava and acrylamide 1:5, 1:10, and 1:15 in 110 mL water. The solution was added with a KPS initiator with weight variations (g) 0.04; 0.08; 0.12 then stirred 15 min. The solution was put in the microwave with 630 watts of irradiation for 450 s with the cooling cycle temperature maintained at 65-70<sup>o</sup>C. The aqueous of grafted polymer and carrageenan was injected into beaker glass that contained 1 cm of palm oil and mixture of 0.2 M CaCl<sub>2</sub> and 0.2 M KCl in an ice bath. Results showed that the highest average swelling capacity was found in the bead gel variation 1:15 with the number of initiators 0.04 g of 1797.95% at a time of 210 minutes of immersion. From FTIR spectrum, it was found that there was a success in grafting acrylamide into bagasse’s backbone using the microwave grafting method with KPS as initiator.

Poly(vinyl alcohol)/modified porous starch gel beads for microbial preservation and reactivation: preparation, characterization and its wastewater treatment performance.

Poly(vinyl alcohol) (PVA)/modified porous starch (MPS) gel beads were prepared through in situ chemical cross-linking by incorporating with MPS, which was obtained by modifying porous starch (PS) with polyethyleneimine (PEI) and glutaraldehyde (GA). Addition of MPS could improve the storage modulus and the effective crosslinking density (ve) of the gel beads, and the mechanical properties were enhanced. The PVA-MPS gel beads were preserved as immobilized microbial carriers for 40 d and reactivated in wastewater. Scanning electron microscope (SEM) observations showed that the beads were highly porous and conducive for microorganism adhesion. The PVA-MPS gel beads were able to remove 97% of ammonia nitrogen and 80% of chemical oxygen demand (COD) after reactivation under all four preservation conditions. The abundance of Hydrogenophaga as denitrifying bacteria on PVA-MPS gel beads increased, with abundance of 8.44%, 5.55%, 8.90% and 9.48%, respectively. It proved that the carrier provided a partial hypoxic environment for microorganisms.

High-throughput bacterial co-encapsulation in microfluidic gel beads for discovery of antibiotic-producing strains.

Bacteria with antagonistic activity inhibit the growth of other bacteria through different mechanisms, including the production of antibiotics. As a result, these microorganisms are a prolific source of such compounds. However, searching for antibiotic-producing strains requires high-throughput techniques due to the vast diversity of microorganisms. Here, we screened and isolated bacteria with antagonistic activity against Escherichia coli expressing the green fluorescent protein (E. coli-GFP). We used microfluidics to co-encapsulate and co-culture single cells from different strains within picoliter gel beads and analyzed them using fluorescence-activated cell sorting (FACS). To test the methodology, we used three bacterial isolates obtained from Mexican maize, which exhibit high, moderate, or no antagonistic activity against E. coli-GFP, as determined previously using agar plate assays. Single cells from each strain were separately co-incubated into gel beads with E. coli-GFP. We monitored the development of the maize bacteria microcolonies and tracked the growth or inhibition of E. coli-GFP using bright-field and fluorescent microscopy. We correlated these images with distinctive light scatter and fluorescence signatures of each incubated bead type using FACS. This analysis enabled us to sort gel beads filled with an antagonistic strain, starting from a mixture of the three different types of maize bacteria and E. coli-GFP. Likewise, culturing the FACS-sorted beads on agar plates confirmed the isolation and recovery of the two antagonistic strains. In addition, enrichment assays demonstrated the methodology's effectiveness in isolating rare antibiotic-producer strains (0.01% abundance) present in a mixture of microorganisms. These results show that associating light side scatter and fluorescent flow cytometry signals with microscopy images provides valuable controls to establish successful high-throughput methods for sorting beads in which microbial interaction assays are performed.

Self-assembly to synchrony of active gels.

Self-assembly functionalizes active constituents to perform rhythmic activities. Here, our results show that the capillary-Marangoni interaction of irregularly moving gel beads develops complex patterns at the air-liquid interface. The collective behavior of the self-assembled structures exhibits breathing dynamics, polygonal oscillating rings, and cluster synchrony of chains. Interestingly, the trapping of soft particles generates relay synchronization of a rotor. Swarming of clusters is found to form rhythmic shrinking and expanding multiple-ring patterns. The development of self-organized spatiotemporal patterns of our active gel system provides a new way of creating collective oscillations.

Influence of composition on the internal diffusion mechanism of pectin–starch gel beads

AbstractPectin is a hydrocolloid commonly used as a wall material for encapsulation, meantime using a filler such as starch can improve the retention in the matrix and control the release in specific places. Formulations of pectin and starch were evaluated for bead production by ionic gelation technique using dripping and jet cutter methods. In addition, beads were dried in a fluidized bed and rotating drum at 50°C. The mean diameter, mechanical strength, yield, moisture content, the morphology of wet and dry beads, and rehydration behavior were evaluated. Furthermore, the pomegranate extract (PE) encapsulation efficiency and release in water were measured. The beads with 2.85% solids content of which 70% are pectin and 30%, waxy corn starch proved to be technologically viable and were satisfactorily dried in a fluidized bed, while on a rotating drum, drying was not efficient. Compared with pure pectin, the pectin–starch beads showed a spherical shape, smoother and more homogeneous with greater mechanical strength and greater water absorption capacity after drying in a fluidized bed. The conventional encapsulation of PE added to biopolymer solutions showed low efficiency (4.7%–43.7%) and the release velocity was higher for drip beads (~70%).

Ammonia-Nitrogen Reduction in Low Strength Domestic Wastewater by Polyvinyl Alcohol (PVA) Gel Beads

This study aimed to evaluate the efficacy of polyvinyl alcohol (PVA) gel beads as an immobilized biofilm carrier to enhance the reduction rate of Ammonia-Nitrogen (NH3-N) and Chemical Oxygen Demand (COD) in domestic wastewater. Laboratory scale reactors were developed to assess the reduction levels of ammonia-nitrogen and COD with and without PVA gel beads using optimal and non-optimal treatment mode settings based on operation procedures from the sewage treatment plant in Taman Kajang Utama, Selangor. The treatment method used is an activated sludge sequencing batch reactor with a treatment cycle duration of 288 minutes. The findings showed the ammonia-nitrogen reduction by non-optimal treatment mode is more effective, with a reduced rate of 62.96% to 65.71% compared to optimal treatment mode with a reduced rate of 30.94% and treatment without PVA gel beads (optimal and non-optimal) with a reduced rate of 32.41% to 47.85%. The ammonia-nitrogen reduction rate using PVA gel beads for non-optimal treatment mode was significantly increased from 17.86% to 18.82% and complied with ammonia-nitrogen reduction parameter 10mg/L, Standard A of Environmental Quality (Sewage) Regulations 2009 (EQSR 2009). The rate of COD reduction using the non-optimal treatment mode was also more stable, with a reduced rate of 70.68%. It was also found that the COD reduction rate using PVA gel beads for the non-optimal mode was better than the optimal mode, which was 70.68% compared to 42.0%, and both treatment modes complied with COD reduction parameters 120mg/L, Standard A of EQSR 2009.

Water adsorption kinetics of silica based porous desiccants by volumetric method

The adsorption kinetics of solid desiccants is critical for the design and optimal operation of air-conditioning systems. However, owing to the complex combination of diffusion processes in the interparticle layer and intraparticle mesopores/micropores, adequately illustrating the adsorption kinetics of solid desiccants is difficult. In this study, the adsorption kinetics of a microsphere silica gel bead was investigated using the volumetric method in a limited batch adsorption system. An analytical solution was adopted for the biporous diffusion model to obtain the effective mesopore diffusivity. A comprehensive diffusion model was developed based on the initial estimation by the analytical solution. The model, i.e., the triple diffusion resistance model that includes three transport resistances, viz., interparticle, mesopore, and micropore resistance was subsequently validated through an experiment. The results show that the rate-limiting step in the entire diffusion and adsorption process changes from intraparticle to interparticle diffusion with increasing sample mass. The proposed model considering the effect of interparticle diffusion successfully determines the effective mesopore diffusivity for each sample mass.

Carbohydrate microcapsules tailored and grafted for covalent immobilization of glucose isomerase for pharmaceutical and food industries.

Carrageenan is one of the most common carbohydrates utilised in the entrapment industry to immobilise cells and enzymes. However, it lacks functionality. Carrageenan has been grafted to produce fructose by covalently immobilising glucose isomerase (GI). Fructose is one of the most widely used sweeteners in beverages, food production, and the pharmaceutical business. Up to 91.1 U g-1 gel beads are immobilised by the grafted beads. Immobilized GI has a Vmax of 13.8 times that of the free enzyme. pH of immobilized GI was improved from 6.5-7 to 6-7.5 that means more stability in wide pH range. Also, optimum temperature was improved and become 65-75°C while it was at 70°C for free enzyme. The immovability and tolerance of the gel beads immobilised with GI over 15 consecutive cycles were demonstrated in a reusability test, with 88 percent of the enzyme's original activity retained, compared to 60 percent by other authors. These findings are encouraging for high-fructose corn syrup producers.

Investigation on ionical cross-linking of alginate by monovalent cations to fabrication alginate gel for biomedical application

It was reported that monovalent cations and Mg2+ ions cannot crosslink alginate to form gels while bivalent cations like Ca2+, Ba2+, Sr2+, Co2+, Ni2+, Zn2+ and Mn2+ions can, so alginate gel beads can be easily produced by dropping an alginate droplet in a bath of metal ion solution. This ready gel-forming ability at mild condition can avoid the inactivation of the drugs, proteins, cells and enzymes and makes alginate extensively used for bioencapsulation. Here, ionically crosslinking of alginate by a monovalent cation, Ag+ ion, was explored. The conditions for the formation of gel beads and the structure and properties of the as-prepared alginate beads were studied. In addition, the possibility of loading drug in the alginate beads was also investigated. The results demonstrate that Ag+ ions do induce gelation of alginate and can be applied to fabricate alginate beads and drug loaded beads like those prepared by using Ca2+ as crosslinking agent.