Yakup Arica

Dithiocarbamate-incorporated monosize polystyrene microspheres for selective removal of mercury ions

Abstract Dithiocarbamate-incorporated monosize polystyrene based microspheres (2 μm in diameter) were used for selective removal of Hg(II) from aqueous solutions containing different amounts of Hg(II) (10–100 ppm). Adsorption rates were observed as high at the beginning of adsorption and then equilibrium was reached in about 30 min. The maximum Hg(II) adsorption capacity of the dithiocarbamate-incorporated PS microspheres was about 33.2 mg per gram of dry polymer, which was observed at pH 7.0. While non-specific Hg(II) adsorption onto the plain microspheres was 0.85 mg per gram of dry microsphere. The Hg(II) adsorption ability increased with increasing pH, in the range where the solubility of the Hg(II) was not affected by the pH. The preferential (i.e., competitive adsorption) binding of Hg(II) by the microspheres implies that this sorbent system might contain higher-affinity binding sites for Hg(II) than Cu(II), Cd(II) and Pb(II) ions. More than 96% of the adsorbed Hg(II) was desorbed in 15 min by using 0.1 M HNO 3 as an elution agent. The regeneration of the dithiocarbamate-incorporated PS microspheres was also sufficient.

Monosize and non-porous p(HEMA-co-MMA) microparticles designed as dye- and metal-chelate affinity sorbents

Abstract Congo red was immobilised onto monosize and non-porous poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) [p(HEMA-co-MMA)] copolymer microparticles (4.0 μm in diameter). Then Fe(III) ions were complexed by chelation with the immobilised congo red molecules. Different amounts of Fe(III) ions were loaded on the dye-derived microparticles by changing the concentration of Fe(III) ions and pH of the reaction medium. Congo red-derived and Fe(III)-complexed microparticles were used in the adsorption of glucose oxidase, catalase, lysozyme and bovine serum albumin. The maximum adsorption capacities of these microparticles were determined by changing pH and the concentration of the proteins in the adsorption medium. Their adsorption behavior can be described at least approximately with the Langmuir equation. Glucose oxidase, catalase, lysozyme and bovine serum albumin adsorption capacities of the Fe(III) complexed microparticles (165.1, 135.2, 67.6 and 44.5 mg g−1) were higher than those of the congo red-immobilised microparticles (125.9, 94.2, 35.8 and 21.2 mg g−1, respectively). The non-specific adsorption of the proteins on the p(HEMA-co-MMA) microparticles was negligible. The resulting dye- and metal-chelate affinity microparticles have excellent reusability and long term storage stability.

Removal of heavy metal ions from aquatic solutions by membrane chromatography

Abstract Polyvinylalcohol membranes were prepared by a solvent casting technique. Metal-complexation ligand, i.e. monochlorotriazinyl-dye Cibacron Blue F3GA was then attached. These membranes with a high water content of 119%, and containing 8.7 mmol Cibacron Blue F3GA/m 2 were used in the adsorption/stripping of some selected heavy metal ions [Cu(II), Hg(II), Pb(II) and Cd(II)] from aquatic solutions containing varying initial concentration of metal ions. Adsorption rates were very high, and equilibrium was achieved in about 10 min. The non-specific adsorption of heavy metal ions on the plain membranes was low [0.63 mmol/m 2 for Cu(II), 0.75 mmol/m 2 for Hg(II), 0.94 mmol/m 2 for Pb(II) and 1.22 mmol/m 2 for Cd(II)]. The maximum adsorptions of heavy metal ions onto the Cibacron Blue F3GA-attached affinity membranes for non-competitive conditions were 16.9 mmol/m 2 for Hg(II), 19.2 mmol/m 2 for Cu(II), 25.8 mmol/m 2 for Pb(II), 32.4 mmol/m 2 for Cd(II). The observed order in adsorption was found to be Cd(II)>Pb(II)>Cu(II)>Hg(II). Different behavior was observed for competitive adsorption. The order of affinity was Cu(II)>Cd(II)>Hg(II)>Pb(II). Regeneration of polyvinylalcohol membranes was done by using 0.1 M HNO 3 in 30 min. Heavy metal ions could be repeatedly adsorbed and stripped without significant decrease in adsorption capacity. The experimental data of adsorption from solutions containing metal ions were found to correlate well with Langmuir isotherm equation.

Protein A-immobilized microporous polyhydroxyethylmethacrylate affinity membranes for selective sorption of human-immunoglobulin-G from human plasma

Microporous membranes made of poly(2-hydroxyethylmethacrylate) [poly(HEMA)] carrying protein A were used for selective sorption of human-IgG from human plasma. Poly(HEMA) membranes were prepared by a photo-polymerization technique, and activated by cyanogen bromide (CNBr) in an alkaline medium (pH 11.5). Bioligand protein A was then immobilized by covalent binding onto these CNBr-activated membranes. The amount of immobilized protein A was controlled by changing pH and the initial concentrations of CNBr and protein A. The non-specific adsorption of protein A on the plain poly(HEMA) membranes was 2.9 μg cm-2. Maximum protein A immobilization was observed at pH 9.5. Up to 186 μg cm-2 was immobilized on the CNBr-activated poly(HEMA) membranes. The maximum adsorption of human-IgG on the protein A-immobilized poly(HEMA) membranes was observed at pH 8.0. The non-specific adsorption of human-IgG onto the plain poly(HEMA) membranes was low (about 4.4 μg cm-2). Higher human-IgG adsorption values (up to 394 μg cm-2) were obtained in which the protein A-immobilized poly(HEMA) membranes were used. Much higher amounts of human-IgG (up to 489 μg cm-2) were adsorbed from human plasma. Up to 91 % of the adsorbed human-IgG was desorbed by using 0.1 M aminoacetic acid as elution agent. The adsorption-desorption cycle was repeated ten times using the same polymeric membranes. There was no remarkable reduction in the adsorption capacity of the protein A-immobilized poly(HEMA) membranes.

Synthesis of Poly[(hydroxyethyl methacrylate)-co-(methacrylamidoalanine)] Membranes and Their Utilization as an Affinity Sorbent for Lysozyme Adsorption

Various adsorbent materials have been reported in the literature for protein separation. We have developed a novel and new approach to obtain high protein-adsorption capacity utilizing a 2-methacrylamidoalanine-containing membrane. An amino acid ligand 2-methacrylamidoalanine (MAAL) was synthesized from methacrylochloride and alanine. Then, poly[(2-hydroxyethyl methacrylate)-co-(2-methacrylamidoalanine)] [p(HEMA-co-MAAL)] membranes were prepared by UV-initiated photopolymerization of HEMA and MAAL. The synthesized MAAL monomer was characterized by NMR spectrometry. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, scanning electron microscopy, FT-IR spectroscopy and elemental analysis. These membranes have large pores; the micropore dimensions are around 5–10 μm. p(HEMA-co-MAAL) affinity membranes with a swelling ratio of 198.9%, and containing 23.9 (mmol MAAL)·m–2 were used in the adsorption of lysozyme from aqueous media containing different amounts of lysozyme (0.1–3.0 mg·ml–1) and at different pH values (4.0–8.0). The effect of Cu(II) incorporation on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the pHEMA membranes was 0.9 μg-cm–2. Incorporation of MAAL molecules into the polymeric structure significantly increased the lysozyme adsorption up to 2.96 mg·cm–2. The lysozyme-adsorption capacity of the membranes incorporated with Cu(II) (9.98 mg·cm–2) was greater than that of the p(HEMA-co-MAAL) membranes. More than 85% of the adsorbed lysozyme was desorbed in 1 h in the desorption medium containing 1.0 M NaCl. The p(HEMA-co-MAAL) membranes are suitable for repeated use for more than 5 cycles without noticeable loss of capacity. These features make p(HEMA-co-MAAL) membrane a very good candidate for bioaffinity adsorption.

Synthesis and adsorption properties of poly(2-hydroxyethylmethacrylate-co-methacrylamidophenylalanine) membranes for copper ions

In the first step of this study, the metal complexing ligand, 2-methacrylamidophenylalanine (MAPA), was synthesized by using methacrylochloride and phenylalanine. The MAPA monomer was characterized by NMR. Then, poly(2-hydroxyethylmethacrylate-co-2-methacrylamidophenylalanine) [p(HEMA-co-MAPA)] membranes were prepared by UV-initiated photo-polymerization of HEMA and MAPA in the presence of an initiator (azobisisobutyronitrile, AIBN). p(HEMA-co-MAPA) membranes were characterized by FTIR and elemental analysis. These p(HEMA-co-MAPA) affinity membranes with a swelling ratio of 133.2%, and containing 18.9 mmol MAPA/m2, were used in the adsorption–desorption of copper(II) ions from synthetic solutions. Adsorption equilibria was reached in about 2 h. The maximum adsorption of Cu(II) ions onto pHEMA was about 0.54 mmol Cu(II)/m2. The MAPA incorporation significantly increased the Cu(II) adsorption capacity by chelate formation of Cu(II) ions with MAPA molecules (23.8 mmol Cu(II)/m2), which was observed at pH 7.0. The chelating membrane can be easily regenerated by 0.1 M HNO3 with higher effectiveness.

Zinc ion-promoted adsorption of lysozyme to Cibacron Blue F3GA-attached microporous polyamide hollow-fiber membranes

Abstract Dye-affinity and metal chelate affinity adsorption are increasingly used for protein separation. Synthetic hollow fiber membranes 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 explore in detail the performance of hollow fibers composed of modified polyamide to which Cibacron Blue F3GA and Zn(II) were attached for adsorption of lysozyme. The polymer matrix was characterized by scanning electron microscopy. These dye-affinity and Zn(II) chelated hollow-fibers were used in the lysozyme adsorption–elution studies. The effects of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye-attached and metal-chelated hollow-fibers were studied in a batch reactor. The effect of Zn(II) loading on lysozyme adsorption was also studied. The non-specific adsorption of lysozyme on the polyamide hollow-fibers was 1.8 mg g −1 . Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 63.2 mg g −1 . Lysozyme adsorption capacity of the Zn(II) chelated hollow-fibers (144.2 mg g −1 ) was greater than that of the Cibacron Blue F3GA-attached hollow-fibers. A significant amount of the adsorbed lysozyme (up to 97%) was eluted in 1 h in the elution medium containing 1.0 M 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 polyamide hollow-fibers can be applied for lysozyme adsorption without causing any significant conformational changes and denaturation. Repeated adsorption/elution processes showed that these novel dye-attached and Zn(II) chelated hollow-fibers are suitable for lysozyme adsorption.

Comparison of adsorption performances of metal–chelated polyamide hollow fibre membranes in lysozyme separation

Abstract Commercially available microporous polyamide hollow fibres are modified by acid hydrolysis to activate the reactive groups and subsequently binding of the ligand, i.e. Cibacron Blue F3GA. Then the Cibacron Blue F3GA-derived hollow fibres were loaded with different metal ions (i.e. Zn(II), Cu(II), Ni(II)) to form the metal chelate. The internal polymer matrix was characterised by scanning electron microscopy. The effects of pH, initial concentration of lysozyme, metal type and temperature on the adsorption of lysozyme to the metal–chelated hollow fibres were examined in a batch reactor. The non-specific adsorption of lysozyme onto the polyamide hollow fibres was 1.8 mg/g. Cibacron Blue F3GA immobilisation increased the lysozyme adsorption up to 62.3 mg/g. Metal–chelated hollow fibres showed a significant increase of the adsorption efficiency. Lysozyme adsorption capacities of Zn(II), Cu(II) and Ni(II)-chelated hollow fibres were different. The maximum capacities of Zn(II), Cu(II) or Ni(II)-chelated hollow fibres were 144.2, 75.2 and 68.6 mg/g, respectively. Significant amount of the adsorbed lysozyme (up to 97%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pH 8.0 and 25 mM EDTA at pH 4.9. Repeated adsorption–desorption process showed that this novel metal–chelated polyamide hollow fibres are suitable for lysozyme adsorption.

HEAVY METAL SEPARATION CAPACITY OF A POROUS METHACRYLAMIDO-PHENYLALANINE CONTAINING MEMBRANE BASED ON A POLYHYDROXY-ETHYL METHACRYLATE MATRIX

The abilities of various sorbent materials for heavy metal removal have been reported in the literature. We have developed a novel approach to obtain high metal-sorption capacity utilizing a membrane containing 2-methacrylamidophenylalanine. Metal-complexing ligand 2-methacrylamidophenylalanine (MAPA) was synthesized through the use methacrylo chloride and phenylalanine. Then, poly(2-hydroxyethylmethacrylate-co-2-methacrylamidophenylalanine) (p(HEMA-co-MAPA)) membranes were prepared by UV-initiated photopolymerization of HEMA and MAPA in the presence of the initiator azobisisobutyronitrile. MAPA monomer was characterized by nuclear magnetic resonance spectroscopy. p(HEMA-co-MAPA) membranes were characterized by swelling studies, scanning electron microscopy, Fourier transform infrared spectroscopy, and elemental analysis. These membranes have large pores; the micropore dimensions are approximately 5–10 μm. p(HEMA-co-MAPA) affinity membranes with a swelling ratio of 133.2% and containing 18.9 mmol MAPA/m2 were used in the removal of the heavy-metal ions of copper, nickel, and mercury from aqueous media containing different amounts of these ions (5–600 mg/L) and at different pH values (2.0–7.0). The maximum adsorption capacities of heavy metal ions onto the MAPA-containing membranes under noncompetitive conditions were 23.8 mmol/m2 for Cu(II), 29.1 mmol/m2 for Ni(II), and 50.3 mmol/m2 for Hg(II). The affinity order was Hg(II) > Ni(II) > Cu(II).The adsorption of heavy metal ions increased with increasing pH and reached a plateau value at approximately pH 5.0. Adsorption of heavy metal ions from artificial wastewater was also studied. The adsorption capacities were 11.9 mmol/m2 for Cu(II), 7.33 mmol/m2 for Ni(II), and 9.79 mmol/m2 for Hg(II). Desorption of heavy metal ions was performed using 0.1 M HNO3. The p(HEMA-co-MAPA) membranes are suitable for more than five cycles without noticeable loss of capacity.

Affinity separation of plasma proteins using a newly synthesized methacrylamidoalanine incorporated porous pHEMA membranes

In this study, we synthesized a novel adsorbent to obtain high protein-adsorption capacity utilizing 2-methacrylamidoalanine (MAAL) containing membrane. Amino acid-ligand MAAL was synthesized by using methacrylochloride and alanine. Then, poly(2-hydroxyethylmethacrylate-co-2-methacrylamidoalanine) [p(HEMA-co-MAAL)] membranes were prepared by UV-initiated photopolymerization of HEMA and MAAL in the presence of an initiator (azobisisobutyronitrile, AIBN). Synthesized MAAL was characterized by nuclear magnetic resonance spectroscopy. p(HEMA-co-MAAL) membranes were characterized by swelling studies, porosimeter, scanning electron microscopy, Fourier transform-infra red spectroscopy, and elemental analysis. These membranes have macropores in the size range 5–10 μm. Different metal ions including Zn(II), Ni(II), Co(II), and Cu(II) were chelated on these membranes. p(HEMA-co-MAAL) were used in the adsorption of human serum albumin (HSA) from aqueous media containing different amounts of albumin (0.1–5.0 mg L−1) and at different pH values (4.0–8.0). The maximum HSA adsorption was observed at pH 5.0. The nonspecific adsorption of HSA on the pHEMA membranes was negligible 0.9 μg cm−2. MAAL incorporation significantly increased the HSA adsorption (1.76 mg cm−2). The HSA adsorption capacities of the metal-incorporated membranes were greater than that of the p(HEMA-co-MAAL) membranes under the same conditions. Higher HSA adsorption capacity was observed from the human plasma (2.88 mg HSA cm−2).