Süleyman Patir

Biosorption of inorganic mercury and alkylmercury species on to Phanerochaete chrysosporium mycelium

Abstract The biosorption of inorganic mercury (HgCl2), methyl mercury (CH3HgCl) and ethyl mercury (C2H5HgCl) onto the dry biomass of Phanerochaete chryosponum was studied from aqueous media which concentrations in the range of 5–500 mg l−1. The surface charge density varied with pH, and the concentration of mercury species adsorbed significantly increased from pH 3.0 to maximum levels at pH 8.0. The biosorption of mercury ions by Phanerochaete chrysosporium increased as the initial concentration of Hg(II) ion increased in the adsorption medium. A biosorption equilibrium were established after about 6 h, the adsorbed Hg(II) ion did not significantly change further with time. The dissociation constant (kd) values were 72, 63, and 61 mg l−1 for CH3HgCl, C2H5HgCl and for Hg(II), respectively. The maximum biosorption capacity (qm) at pH 7.0 was 79 mg for CH3HgCI, 67 mg for C2H5HgCl and 61 mg for Hg(II) per g of dried fungal biomass. The affinity order of mercury species was CH3HgCl>C2H5HgCl>and Hg(II).

Metal-complexing ligand methacryloylamidocysteine containing polymer beads for Cd(II) removal

Different metal-complexing ligands carrying synthetic and natural adsorbents have been reported in the literature for heavy metal removal. We have developed a novel and new approach to obtain high metal adsorption capacity utilizing 2-methacryloylamidocysteine (MAC) as a metal-complexing ligand and/or comonomer. MAC was synthesized by using methacryloyl chloride and cysteine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAC and 2-hydroxyethylmethacrylate (HEMA) conducted in an aqueous dispersion medium. Poly(2-hydroxyethylmethacrylate–methacryloylamidocysteine) p(HEMA–MAC) beads have a specific surface area of 18.9 m2 g−1. p(HEMA–MAC) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA–MAC) beads with a swelling ratio of 72%, and containing 3.9 mmol MAC g−1 were used in the removal of cadmium(II) ions from aqueous solutions. Adsorption equilibrium was achieved in about 15 min. The adsorption of Cd(II) ions onto pHEMA beads was negligible. The MAC incorporation significantly increased the Cd(II) adsorption capacity. Adsorption capacity of MAC incorporated beads increased significantly with pH. Competitive heavy metal adsorption from aqueous solutions containing Cd(II), Cr(III), Pb(II), Hg(II) and As(III) was also investigated. The adsorption capacities are 254 mg g−1 for Cd(II); 90.9 mg g−1 for Cr(III); 150.4 mg g−1 for Hg(II), 91.2 mg g−1 for Pb(II) and 6.7 mg g−1 for As(III) ions. These results are an indication of higher specificity of the p(HEMA–MAC) beads for the Cd(II) ions compared with other ions. Consecutive adsorption and desorption operations showed the feasibility of repeated use for p(HEMA–MAC) chelating beads.

Stimuli-responsive properties of conjugates of N-isopropylacrylamide-co-acrylic acid oligomers with alanine, glycine and serine mono-, di- and tri-peptides.

A random oligomer of N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) with a AAc content of 3.1+/-0.19 mmol carboxylic acid groups per gram of the oligomer and with a number average molecular weight of 1400 was synthesised by a free radical polymerisation using AIBN in DMF. Then, mono-, di-, and tri-peptide conjugates of this oligomer were prepared by using carboxyl-ends-protected (with methyl ester hydrochloride) forms of alanine, glycine and serine, with a water-soluble carbodiimide. 95, 93, and 31% of the carboxylic acids were conjugated (loaded) at the first step (mono-peptides) with glycine, alanine and serine, respectively. At the second step, percentage of the conjugation of carboxylic acid groups with glycine, alanine and serine were between 99 and 80, 68 and 100, and 21 and 58%, respectively, while the third amino acids were attached to only 21-64% of the carboxylic acids available on the conjugate chains. A decrease was observed in the lower critical solution temperatures (LCSTs) of the amino acid conjugates at pH 4.0 compared with the unconjugated oligomer, which has LCST at 37.7 degrees C at the same pH. LCSTs of di- and tri-peptide conjugates at pH 4.0 were in the range of 38.4-43.3 degrees C, and 42.6-50.8 degrees C, respectively. At pH 7.4, LCSTs of the mono- and di-peptide conjugates were observed in the range of 41.6-43.9 degrees C, and 46.2-60.2 degrees C, respectively, while the co-oligomer at pH 7.4 did not show a LCST up to 60 degrees C. Tri-peptide conjugates did not display LCST at pH 7.4, except the one with glycine-alanine-serine sequence.

Cysteine-metal affinity chromatography: determination of heavy metal adsorption properties

Abstract Various adsorbent materials have been reported in the literature for heavy metal removal. We have developed a novel approach to obtain high metal sorption capacity utilising cysteine containing adsorbent. Metal complexing aminoacid-ligand cysteine was immobilised onto poly(hydroxyethylmethacrylate) (PHEMA) microbeads. PHEMA-cysteine affinity microbeads containing 0.318 mmol cysteine/g were used in the removal of heavy metal ions (i.e. copper, lead and cadmium) from aqueous media containing different amounts of these ions (50–400 mg/l for Pb(II) and Cd(II), 25–60 mg/l for Cu(II)) and at different pH values (4.0–7.0). The maximum adsorption capacity of heavy metal ions onto the cysteine-containing microbeads under non-competitive conditions were 0.259 mmol/g for Pb(II), 0.330 mmol/g for Cd(II) and 0.229 mmol/g for Cu(II). The affinity order was observed as follows: Cd(II)>Pb(II)>Cu(II). The competitive adsorption capacities of the heavy metals were 0.260 mmol/g for Cd(II) and 0.120 mmol/g for Cu(II). Pb(II) adsorption onto cysteine-immobilised microbeads was zero under competitive conditions. The affinity order was as follows: Cd(II)>Cu(II)>Pb(II). The formation constants of cysteine–metal ion complexes have been investigated applying the method of Ruzic. The calculated value of stability constants were 1.75×10 4 l/mol for Pb(II)–cysteine complex and 4.35×10 4 l/mol for Cd(II)–cysteine complex and 1.39×10 4 l/mol for Cu(II)–cysteine complex. PHEMA microbeads carrying cysteine can be regenerated by washing with a solution of hydrochloric acid (0.05 M). The maximum desorption ratio was greater than 99%. These PHEMA microbeads are suitable for repeated use for more than three adsorption–desorption cycles without considerable loss in adsorption capacity.

Novel metal complexing ligand: thiazolidine carrying poly(hydroxyethylmethacrylate) microbeads for removal of cadmium(II) and lead(II) ions from aqueous solutions

Abstract Poly(hydroxyethylmethacrylate) (PHEMA) microbeads carrying thiazolidine (0.318 mmol/g) were prepared for the removal of Pb(II) and Cd(II) ions from aqueous solutions containing different amount of these ions (10–600 mg/l) and at different pH values (3.0–7.0). Adsorption rates were high, and adsorption equilibria were reached within 10 min. Adsorption of these metal ions onto the thiazolidine-immobilised microbeads from single solutions were 0.336 and 0.397 mmol/g for Pb(II) and Cd(II), respectively. When the heavy metal ions were in competition, however (in the case of the adsorption from a mixture) the amounts of adsorption were found to be 0.0356 mmol/g for Cd(II) and 0.326 mmol/g for Pb(II); this novel metal chelating system is selective for Pb(II) ions. Therefore it was great importance to know the stability constants of thiazolidine–metal ion complexes. The formation constants of thiazolidine–metal ion complexes were investigated applying the method of Ruzic. The calculated value of stability constants were 1.24×104 l/mol for the Pb(II)–thiazolidine complex and 4.28×102 l/mol for the Cd(II)–thiazolidine complex. These values are in good agreement with the competitive adsorption results. PHEMA microbeads carrying thiazolidine can be regenerated by washing with a solution of hydrochloric acid (0.05 M). The maximum desorption ratio was as high as 99%. PHEMA microbeads are suitable for repeated use for more than three adsorption–desorption cycles without considerable loss of adsorption capacity.

Separation of human-immunoglobulin-G from human plasma with L-histidine immobilized pseudo-specific bioaffinity adsorbents

The pseudo-biospecific affinity ligand l-histidine immobilized poly(2-hydroxyethylmethacrylate) (PHEMA) in spherical form (100–150 μm in diameter) was used for the affinity chromatographic separation of human-immunoglobulin-G (HIgG) from aqueous solutions and human plasma. The PHEMA adsorbents were prepared by a radical suspension polymerization technique. Reactive aminoacid-ligand l-histidine was then immobilized by covalent binding onto these adsorbents. Elemental analysis of immobilized l-histidine for nitrogen was estimated as 62.3 mg l-histidine/g of PHEMA. The maximum HIgG adsorption on the l-histidine immobilized PHEMA adsorbents was observed at pH 7.4. The non-specific HIgG adsorption onto the plain PHEMA adsorbents was very low (about 0.167 mg/g). Higher adsorption values (up to 3.5 mg/g) were obtained when the l-histidine immobilized PHEMA adsorbents were used from aqueous solutions. Much higher amounts of HIgG were adsorbed from human plasma (up to 44.8 mg/g). Adsorption capacities of other blood proteins were obtained as 2.2 mg/g for fibrinogen and 2.8 mg/g for albumin. The total protein adsorption was determined as 52.1 mg/g. The affinity microbeads allowed the one-step separation of HIgG from human plasma. The HIgG molecules could be repeatedly adsorbed and desorbed with these l-histidine-immobilized PHEMA adsorbents without noticeable loss in their HIgG adsorption capacity.

Preparation and Characterization of the Newly Synthesized Metal-Complexing-Ligand N-Methacryloylhistidine Having PHEMA Beads for Heavy Metal Removal from Aqueous Solutions

The aim of this study was to investigate in detail the performance for removal of heavy metal ions of beads composed of poly(2-hydroxyethyl methacrylate) (pHEMA) to which N-methacryloylhistidine (MAH) was copolymerized. The metal-complexing ligand MAH was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 150-200 μm were obtained by the radical suspension polymerization of MAH and HEMA conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA-MAH) beads had a specific surface area of 17.6 m 2 /g. The synthesized MAH monomer was characterized by NMR; p(HEMA-MAH) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA-MAH) beads with a swelling ratio of 65%, and containing 1.6 mmol MAH/g, were used in the adsorption/desorption experiments. Adsorption capacity of the beads for the selected metal ions, i.e., Cu(II), Cd(II), Cr(III), Hg(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (10-750 mg/L) and at different pH values (3.0-7.0). Adsorption equilibria were established in about 20 min. The maximum adsorption capacities of the p(HEMA-MAH) beads were 122.7 mg/g for Cu(II°, 468.8 mg/g for Cr(III), 639.4 mg/g for Cd(II), 714.1 mg/g for Pb(II) and 1234.4 mg/g for Hg(II). pH significantly affected the adsorption capacity of MAH incorporated beads. The chelating beads can be easily regenerated by 0.1 M HNO 3 with high effectiveness. These features make p(HEMA-MAH) beads a potential candidate for heavy metal removal at high capacity.

Preparation of poly(hydroxyethyl methacrylate-co-methacrylamidohistidine) beads and its design as a affinity adsorbent for Cu(II) removal from aqueous solutions

Different metal-complexing ligands carrying synthetic adsorbents have been reported in the literature for heavy metal removal. We have developed a novel and new approach to obtain high metal adsorption capacity utilizing 2-methacrylamidohistidine (MAH) as a metal-complexing ligand. MAH was synthesized by using methacrylochloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and 2-hydroxyethylmethacrylate (HEMA) conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA-co-MAH) beads had a specific surface area of 17.6 m2 g−1. Synthesized MAH monomer was characterized by NMR. p(HEMA-co-MAH) beads were characterized by swelling studies, FTIR and elemental analysis. These p(HEMA-co-MAH) affinity beads with a swelling ratio of 65%, and containing 1.6 mmol MAH g−1 were used in the adsorption/desorption of copper(II) ions from metal solutions. Adsorption equilibria was achieved in ∼2 h. The maximum adsorption of Cu(II) ions onto pHEMA was ∼0.36 mg Cu(II) g−1. The MAH incorporation significantly increased the Cu(II) adsorption capacity by chelate formation of Cu(II) ions with MAH molecules (122.7 mg Cu(II) g−1), which was observed at pH 7.0. pH significantly affected the adsorption capacity of MAH incorporated beads. The observed adsorption order under non-competitive conditions was Cu(II)>Cr(III)>Hg(II)>Pb(II)>Cd(II) in molar basis. The chelating beads can be easily regenerated by 0.1 M HNO3 with higher effectiveness. These features make p(HEMA-co-MAH) beads very good candidate for Cu(II) removal at high adsorption capacity.

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.