Metal chelating properties of Cibacron Blue F3GA‐derived poly(EGDMA‐HEMA) microbeads

Metal chelating properties of Cibacron Blue F3GA‐derived poly(EGDMA‐HEMA) microbeads have been studied. Poly(EGDMA‐HEMA) microbeads were prepared by suspension copolymerization of ethylene glycol dimethacrylate (EGDMA) and hydroxy‐ethyl methacrylate (HEMA) by using poly(vinyl alcohol), benzoyl peroxide, and toluene as the stabilizer, the initiator, and the pore‐former, respectively. Cibacron Blue F3GA was covalently attached to the microbeads via the nucleophilic substitution reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA, under alkaline conditions. Microbeads (150–200 μm in diameter) with a swelling ratio of 55%, and carrying 16.5 μmol Cibacron Blue F3GA/g polymer were used in the adsorption/desorption studies. Adsorption capacity of the microbeads for the selected metal ions, i.e., Cu(II), Zn(II), Cd(II), Fe(III), and Pb(II) were investigated in aqueous media containing different amounts of these ions (5–200 ppm) and at different pH values (2.0–7.0). The maximum adsorptions of metal ions onto the Cibacron Blue F3GA‐derived microbeads were 0.19 mmol/g for Cu(II), 0.34 mmol/g for Zn(II), 0.40 mmol/g for Cd(II), 0.91 mmol/g for Fe(III), and 1.05 mmol/g for Pb(II). Desorption of metal ions were studied by using 0.1 M HNO₃. High desorption ratios (up to 97%) were observed in all cases. Repeated adsorption/desorption operations showed the feasibility of repeated use of this novel sorbent system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1397–1403, 1999     

Albumin adsorption from aqueous solutions and human plasma in a packed-bed column with Cibacron Blue F3GA-Zn(II) attached poly(EGDMA-HEMA) microbeads

Affinity dye-ligand Cibacron Blue F3GA, was covalently coupled with poly(EGDMA-HEMA) microbeads via nucleophilic reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA under alkaline conditions. The microbeads carrying 16.5 μmol Cibacron Blue F3GA per gram polymer was incorporated with Zn(II) ions. Zn(II) loading was 189.6 μmol/g. Cibacron Blue F3GA-Zn(II) attached affinity sorbent was used for albumin adsorption from aqueous solutions and human plasma in a packed-bed column. BSA adsorption capacity of the microbeads decreased with an increase in the recirculation rate. High adsorption rates were observed at the beginning, then equilibrium was gradually achieved in about 60 min. The BSA concentration in the mobile phase also effected adsorption. BSA adsorption was first increased with BSA concentration, then reached a plateau which was about 128 mg BSA/g. The maximum adsorption was observed at pH 5.0 which is the isoelectric pH of BSA. Higher human serum albumin adsorption was observed from human plasma (215 mg HSA/g). High desorption ratios (over 90% of the adsorbed albumin) were achieved by using 1.0 M NaSCN (pH 8.0) in 30 min.     

Cibacron Blue F3GA‐attached magnetic poly(2‐hydroxyethyl methacrylate) beads for human serum albumin adsorption

An affinity dye ligand, Cibacron Blue F3GA, was covalently attached onto magnetic poly(2‐hydroxyethyl methacrylate) (mPHEMA) beads for human serum albumin (HSA) adsorption from both aqueous solutions and human plasma. The mPHEMA beads, in the size range of 80 to 120 µm, were prepared by a modified suspension technique. Cibacron Blue F3GA molecules were incorporated on to the mPHEMA beads. The maximum amount of Cibacron Blue F3GA attachment was obtained as 68.3 µmol g^?1. HSA adsorption onto unmodified and Cibacron Blue F3GA‐attached mPHEMA beads was investigated batchwise. The non‐specific adsorption of HSA was very low (1.8 mg g^?1). Cibacron Blue F3GA attachment onto the beads significantly increased the HSA adsorption (94.5 mg g^?1). The maximum HSA adsorption was observed at pH 5.0. Higher HSA adsorption was observed from human plasma (138.3 mg HSA g^?1). Desorption of HSA from Cibacron Blue F3GA‐attached mPHEMA beads was obtained by using 0.1 M Tris/HCl buffer containing 0.5 M NaSCN. High desorption ratios (up to 98% of the adsorbed HSA) were observed. It was possible to re‐use Cibacron Blue F3GA‐attached mPHEMA beads without any significant decreases in their adsorption capacities. Copyright © 2004 Society of Chemical Industry     

Affinity microspheres and their application to lysozyme adsorption: Cibacron Blue F3GA and Cu(II) with poly(HEMA-EGDMA)

Lysozyme adsorption onto Cibacron Blue F3GA attached and Cu(II) incorporated poly(2-hydroxyethyl methacrylate–ethylene glycol dimethacrylate) [poly(HEMA-EGDMA)] microspheres was investigated. The microspheres were prepared by suspension polymerization. Various amounts of Cibacron Blue F3GA were attached covalently onto the microspheres by changing the initial concentration of dye in the reaction medium. The microspheres with a swelling ratio of 65%, and carrying different amounts of dye (between 1.4 and 22.5 µmol/g⁻¹) were used in the lysozyme adsorption studies. Lysozyme adsorption on these microspheres from aqueous solutions containing different amounts of lysozyme at different pH values was investigated in batch reactors. The lysozyme adsorption capacity of the dye–metal chelated microspheres (238.2 mg g⁻¹) was greater than that of the dye-attached microspheres (175.1 mg g⁻¹). The maximum lyzozyme adsorption capacities (q_m) and the dissociation constant (k_d) values were found to be 204.9 mg g⁻¹ and 0.0715 mg ml⁻¹ with dye-attached and 270.7 mg g⁻¹ and 0.0583 mg ml⁻¹ with dye–metal chelated microspheres, respectively. More than 90% of the adsorbed lysozyme were desorbed in 60 min in the desorption medium containing 0.5 M KSCN at pH 8.0 or 25 mM EDTA at pH 4.9. © 1999 Society of Chemical Industry     

A new metal chelate sorbent for glucose oxidase: Cu(II)- and Co(II)-chelated poly(N-vinylimidazole) gels

Poly(N-vinylimidazole) (PVIm) gels were prepared by irradiating a binary mixture of N-vinylimidazole (VIm)–water in a ⁶⁰Co-γ source having 4.5 kGy/h dose rate. In the glucose oxidase (GOx) adsorption studies, affinity gels with a swelling ratio of 1100% for PVIm and 40 and 55% for Cu(II)- and Co(II)-chelated PVIm gels, respectively, at pH 6.5 in phosphate buffer were used. FTIR spectra were taken for PVIm and Cu(II)- and Co(II)-chelated PVIm, and glucose oxidase adsorption on these gels, to characterize the nature of the interactions in each species. The results show that PVIm–glucose oxidase interaction is mainly electrostatic and metal ion–chelated PVIm gel–glucose oxidase interaction is of coordinate covalent nature. Cu(II) and Co(II) ions were chelated within the gels via amine groups on the imidazole ring of the gel. Different amounts of Cu(II) and Co(II) ions [maximum 3.64 mmol/g dry gel for Cu(II) and 1.72 mmol/g dry gel for Co(II)] were loaded on the gels by changing the initial concentration of Cu(II) and Co(II) ions at pH 7.0. GOx adsorption on these gels from aqueous solutions containing different amounts of GOx at different pH was investigated in batch reactors. GOx adsorption capacity was further increased when Cu(II) and Co(II) ions were attached [up to 0.53 g GOx/g dry Co(II)-chelated PVIm gels]. More than 90% of the adsorbed GOx was desorbed in 5 h in desorption medium containing 1.0M KSCN at pH 7.0 for plain gel and 0.05M EDTA at pH 4.9 for metal-chelated gel. Nonspecific glucose oxidase adsorption on/in the metal ion–chelated PVIm gel was investigated using 0.02M of phosphate buffer solution. The nonspecific GOx adsorption was determined to be about 18% for PVIm and 8% for the metal ion–chelated PVIm gels. The ionic strength effect was investigated both on PVIm and on the metal ion–chelated PVIm gels for the glucose oxidase adsorption. It was found that ionic strength was more effective on the PVIm gel because of the electrostatic interaction between protonated gel and the deprotonated glucose oxidase side chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 446–453, 2001     

木瓜蛋白酶在染料Cibacron Blue F3GA纤维素亲和膜上的吸附研究

以纤维素滤纸膜为载体,染料Cibacron Blue F3GA为配基,制备了一种新型亲和膜色谱介质。采用扫描电镜、红外光谱、元素分析等方法对亲和膜介质进行鉴定与表征,该膜具有良好的色谱性能。亲和膜对F3GA的键合质量摩尔浓度达93.7μmol/g。研究了木瓜蛋白酶在亲和膜上的吸附行为,实验表明:在30℃下、酶质量浓度为2 mg/mL、pH=8.0时,吸附质量比可达57.9 mg/g,改变pH值及离子强度等条件对吸附质量比有明显的影响。在最适条件下吸附遵循Langmuir型吸附。可以初步推断,纤维素滤纸膜可以制成性能优良的亲和膜色谱介质,成本低廉,适合工业化分离纯化生物大分子。     

Dye derived and metal incorporated affinity poly(2-hydroxyethyl methacrylate) membranes for use in enzyme immobilization

Microporous poly(2-hydroxyethyl methacrylate) (PHEMA) membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (α,α′-azobisisobutyronitrile, AIBN). An affinity dye Cibacron Blue F3GA (CB) was attached covalently and then Fe³⁺ ions incorporated. The PHEMA-CB and PHEMA-CB-Fe³⁺ membranes derived were used for adsorption of glucose oxidase (GOD). The adsorption capacities of these membranes were determined under conditions of different pH and with different concentrations of the adsorbate in the medium. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The glucose oxidase adsorption capacity of the Fe³⁺ incorporated membrane (87μgcm^-2) was greater than that of the dye-derived membrane (66μgcm^-2). Non-specific adsorption of the glucose oxidase on the PHEMA membranes was negligible. The K_m values for both immobilized glucose oxidase PHEMA-CB-GOD (8·3) and PHEMA-CB-Fe³⁺-GOD (7·6) were higher than that of the free enzyme (6·2mM). Optimum reaction pH was 5·5 for the free and 6·0 for both immobilized preparations. The optimum reaction temperature of the adsorbed enzymes was 5°C higher than that of the free enzyme and was significantly broader. After 15 successive uses the retained activity of the adsorbed enzyme was 87%. It was observed that enzymes could be repeatedly adsorbed and desorbed on the derived PHEMA membranes without significant loss in adsorption capacity or enzymic activity. © 1998 SCI.     

Synthesis of Cibacron Blue F3GA‐coupled magnetic PMMA nanospheres and their use for protein affinity separation

BACKGROUND: New magnetic carrier separation technologies, capable of treating dilute solutions in large‐scale processes, even in the presence of biological debris, are necessary for the future development of biotechnology. Non‐porous magnetic carriers are more resistant to fouling, show better mass transfer and have lower non‐specific adsorption than porous carriers. Nanosized magnetic carriers have a surface area comparable to that of typical macroporous resins, and therefore their application has advantages. RESULTS: Magnetic poly(methyl methacrylate) (PMMA) nanospheres with an average diameter of 76 nm and narrow size distribution were prepared by a facile mini‐emulsion polymerization. After surface modification with poly(ethylene glycol), Cibacron Blue F3GA (CB) was coupled to the magnetic PMMA nanospheres to form dye ligand‐attached magnetic adsorbents for bovine serum albumin (BSA) adsorption. The CB‐coupled magnetic PMMA nanospheres showed very high adsorption capacity (121.98 mg g^?1) and little non‐specific adsorption for BSA. The adsorbed protein could be easily desorbed using high ionic strength solution. CONCLUSION: The CB‐coupled magnetic PMMA nanospheres showed a high BSA adsorption capacity, low non‐specific adsorption and fast adsorption kinetics in comparison with other dye‐affinity adsorbents. These characteristics indicate that these magnetic PMMA nanospheres have great potential for protein affinity separation and purification. Copyright © 2009 Society of Chemical Industry     

Human serum albumin (HSA) adsorption with chitosan microspheres

In this study, chitosan microspheres were prepared and characterized for adsorption of human serum albumin (HSA) as affinity sorbent. The chitosan microspheres were obtained with a “suspension crosslinking technique” in the size range of 30–700 μm by using a crosslinker, i.e., glutaraldehyde. The chitosan microspheres used in HSA adsorption studies were having the average size of 170 ± 81 μm. Adsorption medium pH and the initial HSA concentration in the adsorption medium were changed as 4.0–7.0 and 0.5–2.0 mg HSA/mL, respectively, to investigate the HSA adsorption capacity of chitosan microspheres. Maximum HSA adsorption (i.e., 11.35 mg HSA/g chitosan microspheres) was obtained at pH 5.0 and 1.5 mg HSA/mL of the initial HSA concentration in the adsorption medium was obtained as the saturation value for HSA adsorption. A very common dye ligand, i.e., Cibacron Blue F3GA was attached to the chitosan microspheres to increase the HSA adsorption capacity. Actually, the HSA adsorption capacity was increased up to 15.35 mg HSA/g chitosan microspheres in the case of Cibacron Blue F3GA attached to chitosan microspheres used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3035–3039, 2002     

In vitro cadmium removal from human serum by Cibacron Blue F3GA–thionein‐complex conjugated affinity membranes

A new membrane affinity biosorbent carrying thionein has been developed for selective removal of cadmium ions from human serum. Microporous poly(2‐hydroxyethyl methacrylate) (pHEMA) membranes were prepared by photopolymerization of HEMA. The pseudo dye ligand Cibacron Blue F3GA (CB) was covalently immobilized on the pHEMA membranes. Then, the cysteine‐rich metallopeptide thionein was conjugated onto the CB‐immobilized membrane. The maximum amounts of CB immobilized and thionein conjugated on the membranes were 1.07 µmol cm⁻² and 0.92 µmol cm⁻², respectively. The hydrophilic pHEMA membrane had a swelling ratio of 58% (w/w) with a contact angle of 45.8 °. CB‐immobilized and CB‐immobilized–thionein‐conjugated membranes were used in the Cd(II) removal studies. Cd(II) ion adsorption appeared to reach equilibrium within 30 min and to follow a typical Langmuir adsorption isotherm. The maximum capacity (q _m) of the CB‐immobilized membranes was 0.203 (µmol Cd(II)) cm⁻² membrane and increased to 1.48 (µmol Cd(II)) cm⁻² upon CB–thionein‐complex conjugation. The pHEMA membranes retained their cadmium adsorption capacity even after 10 cycles of repeated use. © 2000 Society of Chemical Industry     

Comparison of metal chelate affinity sorption of BSA onto Dye/Zn (II)-derived poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) microbeads

Poly(ethylene glycol dimethacrylate-hydroxyethyl methacrylate) [poly-(EGDMA-HEMA)]microbeads in the size range of 150–200 μm were produced by a modified suspension copolymerization of EGDMA and HEMA. The dyes (Congo red, Cibacron blue F3GA, and alkali blue 6B) were covalently immobilized; then, Zn(II) ions were incorporated within the microbeads by chelation with the dye molecules. The maximum amounts of dye loadings were 14.5 μmol/g, 16.5 μmol/g, and 23.7 μmol/g for Congo red, Cibacron blue F3GA, and alkali blue 6B, respectively. Different amounts of Zn(II) ions(2.9–53.8 mg/g polymer) were incorporated on the microbeads by changing the initial concentration of Zn(II) ions and the pH of the medium. Bovine serum albumin (BSA) adsorption onto dye/Zn(II)-derived microbeads containing Congo red, Cibacron blue F3GA, and alkali blue 6B was investigated. The maximum BSA adsorptions onto the dye/Zn(II)-derived microbeads from aqueous solutions containing different amounts of BSA were 159 mg/g, 122 mg/g, and 93 mg/g for the Congo red, Cibacron blue F3GA, and alkali blue 6B dyes, respectively. The maximum BSA adsorptions were observed at pH 6.0 in all cases. Desorption of BSA molecules was achieved by using 0.025M EDTA (pH 4.9). High desorption ratios (more than 93% of the adsorbed BSA) were observed in all cases. It was possible to reuse these novel metal chelate sorbents without significant losses in their adsorption capacities. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2085–2093, 1997     

Preparation of cibacron blue F3GA‐attached polyamide hollow fibers for heavy metal removal

Dye‐affinity adsorption has been used increasingly for heavy metal removal. Synthetic hollow fibers have advantages as support matrices in comparison to conventional bead supports because they are not compressible and they eliminate internal diffusion limitations. The goal of this study was to investigate in detail the performance of hollow fibers composed of modified polyamide to which Cibacron Blue F3GA was attached for the removal of heavy metal ions. The Cibacron Blue F3GA loading was 1.2 mmol/g. The internal matrix was characterized by scanning electron microscopy. No significant changes in the hollow fiber cross‐section or outer layer morphology were observed after dye modification. The effect of the initial concentration of heavy metal ions and medium pH on the adsorption efficiency were studied in a batch reactor. The adsorption capacity of the hollow fibers for the selected metal ions [i.e., Cu(II), Zn(II) and Ni(II)] were investigated in aqueous media with different amounts of these ions (10–400 ppm) and at different pH values (3.0–7.0). The maximum adsorptions of metal ions onto the Cibacron Blue F3GA‐attached hollow fibers were 246.2 mg/g for Cu(II), 133.6 mg/g for Zn(II), and 332.7 mg/g for Ni(II). Furthermore, a Langmuir expression was calculated to extend the adsorption equilibrium. Nitric acid (0.1M) was chosen as the desorption solution. High desorption ratios (up to 97%) were observed in all cases. Consecutive adsorption/desorption operations showed the feasibility of repeated use of this novel sorbent system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3089–3098, 2002; DOI 10.1002/app.2338     

Nonporous monosize polymeric sorbents: Dye and metal chelate affinity separation of lysozyme

Lysozyme adsorption onto dye‐attached nonporous monosize poly(2‐hydroxyethyl‐methacrylate‐methylmethacrylate) [poly(HEMA‐MMA)] microspheres was investigated. Poly(HEMA‐MMA) microspheres were prepared by dispersion polymerization. The monochloro‐triazine dye, Cibacron Blue F3GA, was immobilized covalently as dye–ligand. These dye‐affinity microspheres were used in the lysozyme adsorption–desorption studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye‐attached and metal‐chelated microspheres were studied in a batch reactor. Effect of Cu(II) chelation on lysozyme adsorption was also studied. The nonspecific adsorption of lysozyme on the poly(HEMA‐MMA) microspheres was 3.6 mg/g. Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 247.8 mg/g. Lysozyme adsorption capacity of the Cu(II) incorporated microspheres (318.9 mg/g) was greater than that of the Cibacron Blue F3GA‐attached microspheres. Significant amount of the adsorbed lysozyme (up to 97%) was desorbed in 1 h in the desorption medium containing 1.0M NaSCN at pH 8.0 and 25 mM EDTA at pH 4.9. In order to examine the effects of separation conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We conclude that dye‐ and metal‐chelate affinity chromatography with poly(HEMA‐MMA) microspheres can be applied for lysozyme separation without causing any significant changes and denaturation. Repeated adsorption/desorption processes showed that these novel dye‐attached monosize microspheres are suitable for lysozyme adsorption. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 115–124, 2000     

聚丙烯膜接枝改性亲和膜的制备与表征

采用预辐射接枝法在聚丙烯基膜(PP)上接枝甲基丙烯酸缩水甘油酯(GMA),再将配基辛巴蓝(CBD)固载于GMA聚合链上制备了一种亲和膜.考察了预辐射剂量、接枝单体浓度、反应时间和温度、Mohr's盐浓度对GMA聚合接枝的影响,获得了较佳的条件:GMA浓度20%(v/v),反应温度70℃,反应时间3h,Mohr's盐浓度0.01%(wt),CBD溶液浓度25mg·mL-1.用红外光谱 (FTIR)和扫描电镜 (SEM)分析和观察了该亲和膜的表面形貌特征;在37℃和60mg·L-1的胆红素溶液中对该亲和膜进行静态吸附平衡实验,结果表明,经2.5 h吸附达到平衡,其吸附容量可达50mg·g-1.     

Synthesis of monodisperse nonporous crosslinked poly(glycidyl methacrylate) particles with metal affinity ligands for protein adsorption

Monodisperse nonporous crosslinked poly(glycidyl methacrylate) (PGMA) particles with immobilized metal affinity ligands were prepared for selective recovery of proteins. The PGMA particles, with an average size of 2.2 µm, were prepared by a simple dispersion polymerization of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA). The particles were characterized by scanning electron microscopy (SEM) and Fourier‐transform infrared spectroscopy (FTIR). The epoxy groups of the particles were modified with the metal chelating agent iminodiacetic acid (IDA), which forms metal–IDA chelates at the active sites. After charging with copper ions, the particles were used to recover a model protein, bovine hemoglobin (BHb), in a batchwise manner. The particles had the adsorption capacity of 218.7 mg g⁻¹ with little nonspecific adsorption. The adsorption behavior could be described with the Langmuir equation. The effect of pH on the adsorption was also studied. Regeneration of the metal‐chelated particles was easily performed with 50 mmol L⁻¹ ethylenediaminetetraacetic acid (EDTA), followed by washing with water and reloading with Cu²⁺. The particles could be very useful as an affinity separation adsorbent. Copyright © 2005 Society of Chemical Industry     

New modified poly (ethylene terephthalate) (MPET)-based adsorbent for heavy metal ions

Modified poly(ethylene terephthalate) (MPET) samples of both powder and fiber types, which contain sodium 5-sulfodimethyl isophthalate as the third comonomer component, were explored as an adsorbent for the elimination of heavy metal ions, e.g., Cr³⁺, Pb²⁺, and Cd²⁺, in wastewater. The ions were preferentially adsorbed on finer particles at a lower temperature and pH 4 and were exothermically chemisorbed onto the MPETs via an ionic interaction. It was also found that among the ions Cr³⁺ is the most preferentially adsorbed, followed by Pb²⁺ and Cd²⁺ ions and the adsorption capability of MPETs increased considerably with the presence of phenol. The separation factor indicated that the MPET fiber wastes may possibly be reutilized as an economical adsorbent for heavy metal ions in wastewater.     

Dye‐ligand column chromatography: Albumin adsorption from aqueous media and human plasma with dye‐affinity microbeads

Cibacron Blue F3GA was covalently coupled with poly(ethylene glycol‐dimethacrylate‐2‐hydroxyethylmethacrylate) [poly(EGDMA‐HEMA)] microbeads via the nucleophilic substitution reaction between the chloride of its triazine ring and the hydroxyl groups of the HEMA molecules under alkaline conditions. The affinity sorbent carrying 16.5 μmol Cibacron Blue F3GA/g polymer was then used for bovine serum albumin (BSA) adsorption from aqueous protein solutions and from human plasma in a packed‐bed column. The BSA adsorption capacity of the microbeads decreased with an increase in the recirculation rate. High adsorption rates were observed at the beginning, then equilibrium was gradually achieved in about 60 min. The BSA concentration in the mobile phase was also effective on adsorption. BSA adsorption was first increased with BSA concentration, then reached a plateau that was about 57.3 mg BSA/g. Higher BSA adsorption was observed at lower ionic strength. The maximum adsorption was observed at pH 5.0, which is the isoelectric pH of BSA. Higher human serum albumin adsorption was achieved from human plasma (109.6 mg HSA/g). High desorption ratios (over 94% of the adsorbed albumin) were achieved by using 1.0M NaSCN (pH 8.0) in 30 min. It was observed that albumin could be repeatedly adsorbed and desorbed without a significant loss in adsorption capacity. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2803–2810, 1999     

Characteristics of poly(ether ether ketone) microporous membranes prepared via thermally induced phase separation (TIPS)

The morphology and bulk properties of microporous membranes based on poly (ether ether ketone) (PEEK) have been investigated as a function of initial casting composition and thermal and mechanical processing history. Membranes were prepared via solid—liquid phase separation of miscible blends of PEEK and polyetherimide (PEI), with subsequent extraction of the PEI diluent. Scanning electron microscopy studies revealed a microporous morphology with two distinct pore size scales corresponding to diluent extraction from interfibrillar and interspherulitic regions, respectively. The membrane structure was sensitive to both initial blend composition and crystallization temperature, with the resulting pore size distribution reflecting the kinetics of phase separation. For membranes prepared with lower initial diluent content or at lower crystallization temperatures, mercury intrusion porosimetry indicated a relatively narrow distribution of fine interfibrillar pores, with an average pore size of approximately 0.04 microns. Membranes prepared at higher diluent content or at higher crystallization temperatures displayed a broad pore distribution, with a sizeable population of coarse, interspherulitic pores (0.1 to 1 μm in size). Uniaxial drawing led to a fibrillated network structure with markedly higher water flux characteristics compared to the as-cast membranes. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2347–2355, 1997     

Adsorption of heavy‐metal ions on poly(ethylene imine)‐immobilized poly(methyl methacrylate) microspheres

Poly(methyl methacrylate) (PMMA) microspheres carrying poly(ethylene imine) (PEI) were prepared for the removal of heavy‐metal ions (copper, cadmium, and lead) from aqueous solutions with different amounts of these ions (50–600 mg/L) and different pH values (3.0–7.0). Ester groups in the PMMA structures were converted to imine groups in a reaction with PEI as a metal‐chelating ligand in the presence of NaH. The adsorption of heavy‐metal ions on the unmodified PMMA microspheres was very low [3.6 μmol/g for Cu(II), 4.6 μmol/g for Cd(II), and 4.2 μmol/g for Pb(II)]. PEI immobilization significantly increased the heavy‐metal adsorption [0.224 mmol/g for Cu(II), 0.276 mmol/g for Cd(II), and 0.126 mmol/g for Pb(II)]. The affinity order of adsorption (in moles) was Cd(II) > Cu(II) > Pb(II). The adsorption of heavy‐metal ions increased with increasing pH and reached a plateau value around pH 5.5. Their adsorption behavior was approximately described with the Langmuir equation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 197–205, 2001