Pd(II) ion adsorption onto emulsion gel beads in a fixed bed

We developed previously an emulsion gel adsorbent for improved metal adsorption. This study focuses on a continuous adsorption–desorption process of metal ions from a solution onto emulsion gel beads using the fixed-bed method. The monodisperse millimeter-sized emulsion gel beads, a polymeric hydrogel containing randomly distributed oil microdroplets of di-n-hexylsulfide as an extractant, were prepared using an automatic production method combining sedimentation polymerization and two-fluid atomization. The isotherms and the kinetics for Pd(II) adsorption were investigated. A continuous adsorption–desorption process was successfully demonstrated, and the breakthrough curve was successfully predicted by a mathematical analysis.     

Preparation of poly(N-isopropylacrylamide) hydrogel beads by circulation polymerization

Thermosensitive poly(N-isopropylacrylamide) hydrogel (NIPA hydrogel) beads have attracted much attention due to their applications in reaction and separation processes. This study focuses on the preparation of millimeter-sized, monodispersed NIPA hydrogel beads, for which a novel circulation polymerization technique is proposed. The method involves the drop-wise addition of a pre-gel aqueous solution into swirling silicone oil through a nozzle, and the subsequent conventional free-radical polymerization of the suspended pre-gel droplets, which drifts with the swirling oil. NIPA hydrogel beads that are 3.0 mm in diameter were successfully prepared with a very narrow distribution under fundamental conditions with no coalescence of the pre-gel droplets. The circulation polymerization technique improves the residence time and can be applied to a polymerization system that requires a long gelation time. The size of the resultant hydrogel beads corresponds to the size of the pre-gel droplets that are delivered from the tip of the nozzle, and can be controlled by adjusting the size of the nozzle.     

Elasticity of poly(acrylamide) gel beads

Summary The elastic behavior of swollen ionic poly(acrylamide) (PAAm) gel beads was investigated as a function of the bead diameter. For this purpose, an experimental setup was designed to measure the modulus of hydrogel beads. An inverse suspension polymerization technique was used to obtain spherical beads of sizes 3 to 11 mm. It was observed that the effective crosslink density of PAAm gel beads produced in the same synthesis batch increases with increasing bead diameter, which was attributed to the inverse suspension polymerization condition. Received: 6 November 2002/Revised version: 4 April 2003/ Accepted: 4 April 2003 Correspondence to Oguz Okay     

Thermosensitive poly(N‐isopropylacrylamide) hydrogel for refolding of recombinant bovine prethrombin‐2 from E. coli inclusion bodies

The poly(N‐isopropylacrylamide) (PNIPA) hydrogel, which is a kind of temperature‐sensitive polymer, was synthesized by inverse suspension polymerization. The microscopy and scan electron microscopy (SEM) of PNIPA hydrogel were studied. The microscope photograph showed that the particles were in the range of 0.2–0.5mm in diameter, with numerous conjoint pores about 1–2μm spreading all over the surface of the beads. The swelling properties of PNIPA gel beads indicated that the lower critical solution temperature (LCST) of the gel was 33°C. The PNIPA prepared was applied to the renaturation of bovine prethrombin‐2 (pThr‐2) from inclusion bodies produced in E. coli. It was observed that PNIPA was quite efficient in assisting protein renaturation at high protein concentration. When mixing with 105mg/mL PNIPA hydrogel during the refolding, the total activity of the thrombin was about 6222U/mL, compared with only 2800U/mL by simple dilution refolding. The kinetics of pThr‐2 refolding with the absence or the presence of PNIPA was also studied respectively. The time required for the refolding with PNIPA gel was a little bit longer than that by the dilution method owing to the diffusion resistance of the protein into the network of the gel and the hydrophobic interaction between the protein and the polymer. The mechanism of the enhancement for the PNIPA gel to the refolding was further discussed. The porosity of the PNIPA hydrogel allows penetration of the unfolded protein into the inside of the polymer with a hydrophobic side chain, which can facilitate the formation of intermediate via hydrophobic interaction with the unfolded protein and the folding intermediate that are liable to re‐aggregation. About 1.2mg of purified active thrombin could be recovered from 1 L of cells, which greatly facilitated the scale‐up to the quantities of protein necessary for further functional and structural studies. A novel protein renaturation method mediated by PNIPA hydrogel beads, which highly increases the refolding efficiency with easy handling, recycling, and low cost, was proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1734–1740, 2005     

A novel hydrogel based on agricultural waste for removal of hazardous dyes from aqueous solution and reuse process in a secondary adsorption

A novel hydrogel based on the orange peel (OP) and N-vinyl-2-pyrrolidone was prepared by free-radical polymerization using gamma irradiation. The effect of radiation dose and hydrogel composition on gel content was studied. The formed hydrogel was characterized by FT-IR, TGA, and SEM. The swelling behavior was determined as a function of swelling time, pH, and OP content. The hydrogel swelling was found to be pH dependent, and the diffusion mechanism of water into the hydrogel was found Fickian. The developed hydrogel was used for the removal of Congo red (CR) and methyl orange (MO) dyes from wastewater. The effects of various operating parameters, such as initial pH, contact time, initial dye concentration, and temperature on the removal of dyes, have been investigated. The Langmuir and the Freundlich adsorption models were applied to study the adsorption isotherm. The pseudo-first-order model was proved compatible for CR adsorption and the pseudo-second-order model well described the adsorption of MO. The adsorption of dyes increased with increasing temperature indicating that the endothermic nature of the adsorption process and the thermodynamic parameters was evaluated. Second, the adsorption cycle of dyes was also examined and discussed utilizing the loaded hydrogel with the other dye and cobalt metal ions.     

Encapsulation and delivery of protein from within poly(sulfobetaine) hydrogel beads

Advancement of therapeutic protein therapies can be hindered by their poor stability and short in vivo half-life. There is emerging evidence that biocompatible zwitterionic materials can prevent nonspecific interactions within proteins systems that contribute to protein instability. Here, zwitterionic hydrogel beads are synthesized from poly(sulfobetaine methyl methacrylate), pSB, using an inverse emulsion, free radical polymerization reaction technique. The transport properties within the zwitterionic hydrogels were characterized using ¹H NMR diffusometry. Equilibrium water content as high as 0.90 was measured for the synthesized hydrogels. Our study revealed that the pSB hydrogels are nontoxic, ion responsive, and their swelling is temperature dependent. The zwitterionic hydrogel beads were capable of undergoing lyophilization without aggregation. Hydrogel beads were loaded with a model protein, bovine serum albumin (BSA), using a postfabrication loading technique. The protein loading was studied using confocal laser microscopy, indicating homogenous protein dispersion of up to 40 μg BSA/mg hydrogel within the beads. Furthermore, the release rate of the protein from the synthesized hydrogel was studied at different crosslinker to monomer ratios. The protein encapsulated within the zwitterionic hydrogel had slower rates of thermal aggregation compared to nonencapsulated protein in solution. Furthermore, the protein-loaded inside the zwitterionic hydrogel better maintained its bioactivity.     

2‐Hydroxypropylmethacrylate based mono‐ and bifunctional gel beads prepared by suspension polymerization

Spherical and swellable gel beads in the size range 35–200 µm were prepared by suspension polymerization of 2‐hydroxypropylmethacrylate (HPMA). In the proposed method, a mixture of cyclohexanol and octanol was used as a diluent phase dispersed in an aqueous medium including poly(vinyl pyrrolidone) (PVP) as the stabilizer. The polymerization was initiated within the organic phase including the monomer and the crosslinker (ethylene glycol dimethacrylate) by an oil soluble initiator benzoyl peroxide. Spherical and swellable gel beads carrying both hydroxyl and carboxyl functional groups were also prepared by suspension copolymerization of HPMA and a water soluble comonomer (methacrylic acid). For this purpose, the suspension polymerization method proposed for HPMA was modified by using poly(vinyl alcohol) as a stabilizer instead of PVP. The effect of initiator concentration, polymerization temperature, monomer/diluent ratio, crosslinker concentration, stirring rate on yield, average size, size distribution, and carboxyl content of the HPMA based gel beads, were investigated. The swelling characteristics of the gel beads were defined. © 2000 Society of Chemical Industry     

New approach to the formulation of hydrogel beads by emulsification/thermal gelation using a static mixer

A new approach in the formulation of hydrogel beads by emulsification/in situ thermal gelation using static mixer technology is described. κ-Carrageenan was selected as the model hydrogel. The emulsion generated by a Sulzer SMX6 static mixer consisted of warm κ-carrageenan sol (1.5% w/w in water or ) as the dispersed phase, and ambient temperature sunflower seed oil as the continuous phase. Dispersion followed by in situ gelation of κ-carrageenan droplets was possible within a short residence time (1-) in the static mixer, under defined operational conditions, known as the feasibility region. This region was defined as the zone of operation conditions necessary to obtain discrete gel beads, within a defined range of κ-carrageenan solution injection temperature, volume fraction and total flowrate. The temperature boundaries of the feasibility region were determined by the κ-carrageenan gelation temperature and solution viscosity. The resulting beads had a Sauter mean diameter ranging from 350 to , which decreased with the increase of κ-carrageenan injection temperature, total flowrate and/or the number of static mixer elements. Theoretical values of maximal bead diameter and Sauter mean diameter were calculated on the base of critical Weber number, which was demonstrated through good agreement with the experimental values. It was demonstrated that an existing model for the prediction of gel bead diameter in a SMX static mixer is applicable for the new procedure described in this study.     

Inverse emulsion free‐radical polymerization of acrylamide terpolymer for enhanced oil recovery application in harsh reservoir conditions

A free‐radical inverse emulsion polymerization formulation has been developed for preparation of acrylamide (AAm)/sodium 2‐acrylamido‐2‐methylpropanesulfonate (AMPSNa)/N‐vinylpyrrolidone (VP) terpolymers. An aqueous solution of a blend of monomers is emulsified in n‐decane using Tween 85 (Tw85). Ammonium persulfate (APS) and dicumyl peroxide (DCP) were used as initiators for water and oil phases, respectively. The reactions were catalyzed by temperature and by a redox pair; the former is achieved at 60°C and the latter by adding tetramethylethylenediamine (TEMED) and sodium bisulphite (BisNa) to activate the initiator in water and oil phase, respectively. The emulsion type, stability, conversion, and rate of polymerization were analyzed. The obtained terpolymer was characterized by elemental analysis, infrared spectroscopy (FTIR), ¹³C nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and rheology. Thermal catalyzed emulsion polymerization initiated with DCP showed the best performance as viscosity control agent and as polymeric precursor for in situ gel forming, for water mobility control and flow diversification, respectively. Both application for enhanced oil recovery purposes in harsh oil reservoir conditions are presented. POLYM. ENG. SCI., 57:1214–1223, 2017. © 2017 Society of Plastics Engineers     

Microporous polyurethane/acrylate gel polymer electrolyte obtained by emulsion polymerization

A novel polyurethane/acrylate (PUA) porous gel electrolyte was prepared by a new method, emulsion polymerization. Compared with the traditional phase inversion method, the new method can eliminate the pollution from solvent and decrease the cost of production. The swelling properties and morphology of the porous polymer membranes were characterized. The porous membranes, made by emulsion polymerization, could absorb large quantities of electrolyte solution to form porous gel electrolytes. The gel electrolytes have good solvent retention ability and high ionic conductivity. Copyright © 2004 Society of Chemical Industry     

表面羧基化聚丙烯酸酯多孔微球的制备及其铜离子吸附性能研究

以浓乳液作为悬浮聚合的油相,采用水（W）/油（O）/W浓乳液/悬浮聚合方法制备出了内部具有通孔结构、粒径均一的聚甲基丙烯酸叔丁酯多孔微球。结果表明,通过研究乳化剂含量、搅拌速度等参数对多孔微球的内部微孔形貌与微球粒径的影响,发现当乳化剂含量为4 %时,得到的聚合物微球内的微孔结构分布均匀;而聚合物微球的平均粒径会随着搅拌速度的增大而减小。将不同粒径的多孔微球进行酸化水解后得到了表面羧基官能化的聚合物多孔微球,利用其丰富的通孔结构实现了对铜离子（Cu²⁺）的有效吸附,当微球平均粒径介于200~300 μm时,铜离子的去除率最高,可达99.3 %。     

Mass transfer coefficients of styrene and oxygen into silicone oil emulsions in a bubble reactor

The absorption of oxygen and styrene in water-silicone oil emulsions was independently studied in laboratory-scale bubble reactors at a constant gas flow rate for the whole range of emulsion compositions (0-10% v/v). The volumetric mass transfer coefficients to the emulsions were experimentally measured using a dynamic absorption method. It was assumed that the gas phase contacts preferentially the water phase. In the case of oxygen absorption, it was found that the addition of silicone oil hinders oxygen mass transfer compared to an air-water system. Decreases in k_La_oxygen of up to 25% were noted. Such decreases in the oxygen mass transfer coefficient, which imply longer aeration times to transfer oxygen, could represent a limiting step in biotechnological processes strongly dependent on oxygen concentration. Nevertheless, as the large affinity of silicone oil for oxygen enables greater amounts of oxygen to be transferred from the gas phase, it appears that the addition of more than 5% silicone oil should be beneficial to increase the oxygen transfer rate. In the case of styrene absorption, it was established that the volumetric mass transfer coefficient based on the emulsion volume is roughly constant with the increase in the emulsion composition. In spite of the relatively high cost of silicone oil, water-silicone oil emulsions remain relevant to treat low-solubility volatile organic compounds, such as styrene, in low-concentration gas streams.     

Development of a novel microorganism immobilization method using anionic polyurethane

A new microorganism immobilization method involving gelation of anionic polyurethane has been developed. Nontoxic synthetic anionic polyurethane was used, which provides greater mechanical strength than do natural polymers. Similar to the formation of Ca‐alginate gel beads, this method has the advantage of easy preparation. Gel beads are formed only by dropping the anionic polyurethane emulsion into a calcium chloride solution. The feasibility of the proposed immobilization method was tested by an ethanol production process with baker's yeast (Saccharomyces cerevisiae). The result verified that the anionic polyurethane entrapped–cell method developed in this study has great potential for a variety of applications such as biological processes and biological wastewater treatment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 738–743, 2006     

Hollow,pH‐sensitive calcium–alginate/poly(acrylic acid) hydrogel beads as drug carriers for vancomycin release

In this study, hollow calcium–alginate/poly(acrylic acid) (PAA) hydrogel beads were prepared by UV polymerization for use as drug carriers. The hollow structure of the beads was fortified by the incorporation of PAA. The beads exhibited different swelling ratios when immersed in media at different pH values; this demonstrated that the prepared hydrogel beads were pH sensitive. A small amount (<9%) of vancomycin that had been incorporated into the beads was released in simulated gastric fluid, whereas a large amount (≤67%) was released in a sustained manner in simulated intestinal fluid. The observed drug‐release profiles demonstrated that the prepared hydrogel beads are ideal candidate carriers for vancomycin delivery into the gastrointestinal tract. Furthermore, the biological response of cells to these hydrogel beads indicated that they exhibited good biological safety and may have additional applications in tissue engineering. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

One-step synthesis of pH-sensitive poly(Acrylamide-co-Sodium Acrylate) beads with core–shell structure

This work describes a novel one-step method to prepare poly(AMm-co-AAcNa) pH-sensitive hydrogel beads with core–shell structure induced by a spontaneous phase separation process during polymerization. In virtue of the phase separation process, polymers with high molecular weight separate to the core phase whereas monomers are left in the shell. This redistribution inside the droplets enables the polymerization environment change sharply to endow the beads with different network structure in core and shell. FTIR spectrum and EDS show that core and shell share identical composition; yet GPC exhibits a bimodal molecular weight distribution which lead to a conventional network in core but a rich-in-branch network in shell. This difference in structure results in mainly three discrepancies in performance. The level of volume change that the beads exhibit at about pH = 4 is much more intense for shell than for core; the swelling/shrinking kinetics of the core and shell indicates that shell responses about 30 times faster than core does; fitting of the absorbency capacity exhibited that the ones of the core and shell are about 67 g/g and 2126 g/g, respectively. A microfluidic device with co-axial channel structure is introduced in this fabrication. The hydrogel beads exhibited narrow size distribution and the diameter of core and shell could be freely controlled by the high controllability of microfluidic technology and by manipulating the phase separation process. In sum, this method impart us an easy and fast-running way to obtain hydrogel beads with core–shell structure, which has potential in various applications like optical material, lenses and sensors.     

Accelerated Preparation of Novel Bacterial Cellulose/Acrylamide-Based Hydrogel by Microwave Irradiation

The fabrication of novel bacterial cellulose/polyacrylamide-based hydrogels by accelerated radiation by microwave was investigated. This study was designed and optimized using the Taguchi method by taking irradiation time and power as the main parameters. The results revealed the dependence of percentage gel fraction and swelling index on the synthesis parameters using a microwave. The gel fraction was proportionally increased with power and time. The bacterial cellulose fibers crosslinked with polyacrylamide polymer chain as the thermal energy in the monomer mixture quickly rose, leading to a higher degree of polymerization. A highly time-efficient processing with interchangeable parameters allows various hydrogel properties to be developed.     

Direct Generation of Mn‐Doped ZnS Quantum Dots/Alginate Nanocomposite Beads Based on Gelation and In Situ Synthesis of Quantum Dots

Herein, a concise and novel method is developed to directly generate Mn‐doped ZnS QDs/alginate nanocomposite beads. In this method, the ionic gelation of alginate is employed to produce alginate gel beads in a solution of Zn²⁺ and Mn²⁺ ions. Subsequently, the gel beads serve as the reaction support for in situ synthesis of Mn‐doped ZnS QDs in the beads through the reaction of sodium sulfide with Zn²⁺ and Mn²⁺ ions. The method has many benefits such as the simple preparation, the environmentally friendly process, the mild conditions, and the easy post‐treatment for the beads. The resulting QDs/alginate beads are homogeneous and stable gel spheres which show clear fluorescence. TEM images demonstrate that Mn‐doped ZnS QDs are homogeneously distributed within the QDs/alginate nanocomposite, and their average size is 2.4 ± 0.3 nm. Potentially, the QDs/alginate beads can be utilized for fluorescence bioimaging, as well as fluorescence detection toward metal ions.     

Synthesis,structure, and selective separation behavior of copper‐imprinted microporous polymethacrylate beads

Metal ion‐imprinted polymethacrylate beads with sizes ranging from 100 to 300 μm were prepared by suspension polymerization for the application of selective separation of target metal ions. The metal ion contacting area of the beads was enlarged via pore formation (BET 425 m²/g) using toluene as a porogenic agent. The synthesis of the copper‐imprinted porous beads was verified using FTIR, SEM, and ESCA. Separation capacity and selectivity were investigated carrying out column separation experiments. The selective adsorption behavior of the imprinted beads was significantly affected by flow rate, pH, and metal ion concentration in the solution. Adsorption of the copper ion, the template metal ion, onto the beads was highly selective, compared with other ions such as nickel and zinc, with the selective coefficients at approximately 5–10. The microporous particles possessing such high selectivity has a potential application as novel column packing materials especially requiring high selective efficiency, which is usually not achievable by commercial ion exchange resins. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

MATERIAUX TRIPHASIQUES ALVEOLAIRES POLYMERE / CHARGE / LIQUIDE OU GAZ. Préparation de Matériaux triphasiques Polystyrène / billes de Verre / Eau ou Air

New three phases composite materials made of glassbeads as filler, water as liquid dispersed phase and polystyrene as matrix were obtained by polymerization of a water in oil emulsion formed by water dispersed in styrene in which glass beads are added. For this purpose glass beads have to be modified by silanization by a coupling agent 3-(Trimethoxysilyl)propylmethacrylate (TPM) or a silane Octadecyltrichlorosilane (ODMS), in order to prevent the wetting of the glass by water. Only low coverage of the glass surface by the coupling agent (0,05% of TPM) are convenient for the preparation cellular materials having good mechanical properties. At higher coverage ratio, strong hydrophobic glass beads are obtained which destabilize the water / styrene emulsion and lead to macroporous products. Study of the rheology of the filled emulsion appears to be the more simple and more sensitive method to determine the level of wettability of the glass bead by the emulsion which is the most significant parameter for the preparation of such three phases composite materials. Composite materials made of glass beads, air and polystyrene are simply obtained by evaporation of water under vacuum.     

垂直上升管内气体扰动油水两相乳化液流动特性

气体 -油水乳化液的管内流动是原油开采、油气输运以及许多化工领域中经常遇到的工程现象 ,正确认识油水乳化液在气体扰动下的动力特性对圆管内油、气、水多相流的理论建模具有重要的工程应用和学术价值 .本文通过垂直上升管内油气水三相弹状流的实验研究 ,提出了垂直上升弹状流中油水乳化液黏度计算模型 .基于此模型 ,油水乳化液在气体掺入下的流动特性可表现为气体扰动变稠的非牛顿流体特性和气体扰动变稀的非牛顿流体特性 .