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

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.     

Synthesis, characterization and thermal analysis of some new transition metal complexes of a polydentate Schiff base

A new polydentate Schiff base (H3L) was synthesized from the condensation of 2,6-diformyl-4-methylphenol and S-methylhydrazine-carbodithionate. The 1:1 metal complexes were obtained from the interaction of H3L and the metal ions Cr(III), Co(II), Ni(II), Cu(II), Cd(II) and Hg(II). The complexes were characterized by elemental analysis and IR spectroscopy. Detailed studies of the thermal properties of the complexes were investigated by thermogravimetry techniques.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Transition metal complexes of Schiff base ligand based on 4,6-diacetyl resorcinol

Novel Schiff base ligand based on the condensation of 4,6-diacetyl resorcinol with 2-amino-4-methylthiazole in addition to its metal complexes with Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) ions have been synthesized. The structure, electronic properties, and thermal behaviour of Schiff base and its metal complexes have been studied by elemental analysis, mass, ¹H NMR, IR spectra, thermal analysis, and theoretically by density function theory. The ligand acted as mononegative bidentate (NO) ligand and all complexes showed octahedral geometry except Cu (II) showed tetrahedral geometry as indicated from the spectral and magnetic studies. The Cu (II), Zn (II) and Cd (II) complexes were non electrolytes while the rest of the complexes were electrolytes. The antibacterial plus anticancer activities of the parent Schiff base and its metal complexes were screened. In addition, the molecular docking study was performed to explore the possible ways for binding to Crystal Structure of Human Astrovirus capsid protein (5ibv) receptor.     

Adsorption behavior of metal ions onto a bovine serum albumin (BSA) membrane monitored by means of an electrode-separated piezoelectric quartz crystal.

The interaction between metal ions and bovine serum albumin (BSA) was studied by using a piezoelectric quartz crystal (PQC) arranged in the electrode-separated configuration. A silanized surface of the PQC was coated with a BSA membrane via a coupling reaction with glutaraldehyde. The frequency shifts obtained from PQC coated with a BSA membrane suggested that various kinds of metal ions could be adsorbed onto the BSA membrane from aqueous solutions containing a low concentration of metal ions (2 or 10 micromol dm(-3)), only when the BSA was denatured with an alkaline solution. Anionic species of Pt(IV) and Au(III) were adsorbed onto the denatured BSA membrane from an acetic acid solution at pH 2.2, and cationic species of Cd(II), Zn(II), Co(II), Ni(II), Cu(II), and Ag(I), and cations, such as Ca2+, Ba2+, and Mg2+, were adsorbed from ammonia buffer at pH 9.5, whereas Al(III), Cr(III), Fe(III), Hg(II), and Pb(II) were hardly adsorbed. The adsorption mechanisms of these metal ions are discussed, based on the electrostatic interaction between the metal ions and the denatured BSA membrane, and complex formation between the metal ions and amino acid residues of the denatured BSA. Further, the PQC coated with a denatured BSA membrane was applied to the determination of Pt and Cd, using large frequency shifts for Pt(IV) and Cd(II).     

Adsorption of heavy metal ions onto dithizone-anchored poly (EGDMA-HEMA) microbeads

The dithizone-anchored poly (EGDMA-HEMA) microbeads were prepared for the removal of heavy metal ions (i.e. cadmium, mercury, chromium and lead) from aqueous media containing different amounts of these ions (25-500 ppm) and at different pH values (2.0-8.0). The maximum adsorptions of heavy metal ions onto the dithizone-anchored microbeads from their solutions was 18.3, Cd(II); 43.1, Hg(II); 62.2, Cr(III) and 155.2 mg g(-1) for Pb(II). Competition between heavy metal ions (in the case of adsorption from mixture) yielded adsorption capacities of 9.7, Cd(II); 28.7, Hg(II); 17.6, Cr(III) and 38.3 mg g(-1) for Pb(II). The same affinity order was observed under non-competitive and competitive adsorption, i.e. Cr(III)>Pb(II)>Hg(II)>Cd(II). The adsorption of heavy metal ions increased with increasing pH and reached a plateaue value at around pH 5.0. Heavy metal ion adsorption from artificial wastewater was also studied. The adsorption capacities are 4.3, Cd(II); 13.2, Hg(II); 7.2, Cr(III) and 16.4 mg g(-1) for Pb(II). Desorption of heavy metal ions was achieved using 0.1 M HNO(3). The dithizone-anchored microbeads are suitable for repeated use (for more than five cycles) without noticeable loss of capacity.     

麦麸对重金属离子的吸附性能研究

以麦麸为天然吸附剂,从水溶液中去除重金属离子.实验表明,麦麸对重金属离子有优良的吸附性能.在约10min内达到吸附平衡,吸附容量分别为:Hg2 70mg/g、Pb2 63mg/g、Cd2 21mg/g、Cu2 15mg/g、Ni2 13mg/g及Cr3 9.3mg/g;吸附速率很快,并且对上述金属离子有良好的选择性.     

Novel dye-attached macroporous films for cadmium, zinc and lead sorption: Alkali Blue 6B-attached macroporous poly(2-hydroxyethyl methacrylate)

Alkali Blue 6B-attached poly(2-hydroxyethyl methacrylate) (poly(HEMA)) microporous films were investigated as chelate forming sorbents for heavy metal removal. Poly(HEMA) microporous films were prepared by UV-initiated photo-polymerization of HEMA in the presence of an initiator (azobisisobutyronitrile (AIBN)). Alkali Blue 6B was attached covalently. These films with a swelling ratio of 58%, and carrying 14.8 mmol Alkali Blue 6B m(-2) which were then used in the removal of Cd(II), Zn(II) and Pb(II) from aqueous media. Adsorption rates were very high, equilibrium was achieved in about 30 min. The maximum adsorption of heavy metal ions onto the Alkali Blue 6B-attached films were 41.4 mmol m(-2) for Cd(II), 52.4 mmol m(-2) for Zn(II), and 64.5 mmol m(-2) for Pb(II). When the heavy metal ions competed during the adsorption from a mixture the adsorption values for Cd(II), Zn(II) and Pb(II) were quite close. Heavy metal ions were desorbed by using 0.1 M HNO(3). A significant amount of the adsorbed heavy metal ions (up to 95%) could be desorbed in 30 min. Repeated adsorption/desorption cycles showed the feasibility of these novel dye-attached microporous films for heavy metal removal.     

Removal of heavy metals by using adsorption on alumina or chitosan

The removal of heavy metals from wastewater by using activated alumina or chitosan as adsorbers was evaluated. Cd(II) and Cr(III) were employed as models of the behaviour of divalent and trivalent metal ions. The adsorption of Cd(II) and Cr(III) onto the adsorbers evaluated was studied as a function of pH, time, amount of adsorber, concentration of metal ions and sample volume. A 0.4-g portion of activated alumina can retain 0.6 mg Cr(III) and 0.2 mg Cd(II) from 20 mL sample adjusted at pH 4 and stirred for 30 min. It is therefore possible to totally decontaminate 500 mL of a waste containing 5 mg L(-1) Cd(II) and Cr(III) with 10 g alumina. On the other hand, 0.4 g chitosan can totally decontaminate 20 mL of a pH 5 solution containing up to 50 mg L(-1) Cd(II) and Cr(III). A 99.2+/-0.1% retention of Cd(II) and 83+/-1% retention of Cr(III) was obtained from 500 mL of a laboratory waste. The aforementioned strategies were applied for the minimization of analytical chemistry teaching laboratories and atomic spectrometry laboratory wastes. On comparing both adsorbers it can be concluded that chitosan is more preferable than alumina due to the reduced price of chitosan and the absence of side-pollution effects.     

Selective Adsorption and Determination of Hexavalent Chromium in Water Samples by Chemically Modified Activated Carbon with Tris(hydroxymethyl)aminomethane

This study introduces a sensitive and simple method for selective adsorption of hexavalent chromium, Cr(VI), from water samples prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The method utilized activated carbon modified with tris(hydroxymethyl)aminomethane (AC-TRIS) as an adsorbent. Surface properties of the new chemically modified AC-TRIS phase were confirmed by Fourier transform infrared (FTIR) spectroscopy. Seven metal ions, including Co(II), Cu(II), Ni(II), Pb(II), Cr(III), Cr(VI), and Fe(III) were evaluated and determined at different pH values (1.0–8.0), except for Fe(III) at pH values (1.0–4.0). Based on the results of the effect of pH on adsorption of these metal ions on AC-TRIS, Cr(VI) was selected for the study of other parameters controlling its maximum uptake on AC-TRIS under batch conditions and at the optimum pH value 1.0. The maximum static adsorption capacity of Cr(VI) onto the AC-TRIS was found to be 43.30 mg g^?1 at this pH and after 1 hour contact time. The adsorption data of Cr(VI) were modeled using both Langmuir and Freundlich classical adsorption isotherms. Results demonstrated that the adsorption of Cr(VI) onto AC-TRIS followed a pseudo second-order kinetic model. In addition, the efficiency of this methodology was confirmed by applying it to real environmental water samples.     

Complexation of transition metals with 8-hydroxyquinoline chemically immobilized on the surface of a silica gel-polyaniline composite

The complex-forming properties of a silica gel-polyaniline composite with 8-hydroxyquinoline covalently immobilized by the Mannich reaction with respect to Pb(II), Cd(II), Cu(II), Ni(II), Co(II), Al(III), Fe(III), and Mo(VI) ions were studied. The resulting adsorbent had a high sorption capacity and satisfactory kinetic characteristics, which allowed us to use it for the separation or preconcentration of transition metal ions. Data on the composition and structure of the test metal complexes with 8-hydroxyquinoline immobilized on the composite surface were obtained from an analysis of electronic diffuse reflectance spectra and corresponding adsorption isotherms.     

Synthesis and characterization of silica gel microspheres encapsulated by salicyclic acid functionalized polystyrene and its adsorption of transition metal ions from aqueous solutions

The present study was undertaken to develop a novel adsorbent for heavy metal ions, and this paper presents the synthesis and characterization of a composite material-silica gel microspheres encapsulated by salicyclic acid functionalized polystyrene (SG-PS-azo-SA) with a core-shell structure. SG-PS-azo-SA was used to investigate the adsorption of Mn(II), Co(II), Ni(II), Fe(III), Hg(II), Zn(II), Cd(II), Cr(VI), Pd(II), Cu(II), Ag(I), and Au(III) from aqueous solutions. The results revealed that SG-PS-azo-SA has better adsorption capacity for Cu(II), Ag(I) and Au(III). Langmuir and Freundlich isotherm models were applied to analyze the experimental data, the best interpretation for the experimental data was given by the Langmuir isotherm equation with the maximum adsorption capacity for Cu(II), Ag(I), and Au(III) at 1.288 mmol g⁻¹, 1.850 mmol g⁻¹ and 1.613 mmol g^t-1, respectively. Thus, silica gel encapsulated by salicyclic acid functionalized polystyrene (SG-PS-azo-SA) is favorable and useful for the removal of Cu(II), Ag(I) and Au(III) metal ions.     

Tuning the selectivity of two chemosensors to Fe(III) and Cr(III)

Two rhodamine-based chemosensors (1 and 2) were designed, and their sensing behavior toward metal ions was investigated by fluorescence spectroscopies. 1 and 2 achieved tuning the selectivity to Fe(III) and Cr(III) in 100% aqueous solution, whereas other ions including Cd(II), Co(II), Cu(II), Ni(II), Zn(II), Mg(II), Ba(II), Pb(II), Na(I), and K(I) induced basically no spectral change, which constituted a Fe(III)-selective and a Cr(III)-selective fluorescent chemosensor, respectively.     

Synthesis,characterization and susceptibility of bacteria against Sulfamethoxydiazine complexes of copper(II), zinc(II), nickel(II), cadmium(II), chromium(III) and iron(III)

Complexes of sulfamethoxydiazine with Cu(II), Zn(II), Ni(II), Cd(II), Cr(III) and Fe(III) have been synthesized and characterized on the basis of conductivity measurements, elemental analyses, UV, IR, ¹H?NMR and thermal studies. It is shown that sulfamethoxydiazine behaves as a bidentate ligand, binding the metal ion through the sulfonyl oxygen and sulfonamide nitrogen. In vitro susceptibility tests of these complexes against Escherichia coli, Bacillus subtilis, Proteus vulgaris and Staphylococcus aureus were carried out. The results show that the antibacterial activities of the complexes of Zn(II), Cu(II), Cr(III) and Fe(III) are, in general, stronger than that of sulfamethoxydiazine, while the complexes of Cd(II) and Ni(II) are less active.     

Spectroscopic studies of bimetallic complexes derived from tridentate or tetradentate Schiff bases of some di- and tri-valent transition metals

Two series of new binuclear complexes with Schiff base ligands, H(4)L(a) or H(2)L(b), derived from the reaction of 4,6-diacetylresorcinol and ethylenediamine, in the molar ratio 1:1 and 1:2 have been prepared, respectively. The two ligands react with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Cr(III) and Fe(III)-nitrates to get binuclear complexes. The ligands were characterized by elemental analysis, IR, UV-vis, (1)H NMR and mass spectra. The complexes were synthesized by direct and template methods. Different types of products were obtained for the same ligand and metal salts according to the method of preparation. The H(4)L(a) ligand behaves as a macrocyclic tetrabasic with two N(2)O(2) sits, while the H(2)L(b) ligand behaves as a dibasic with two N(2)O sites. The H(4)L(a) ligand is a compartmental ligand which hosts the two metal ions at the centers of two cis-N(2)O(2) sites, while the metal complexes of H(2)L(b) ligand are binuclear, where the ligand hosts two metal ions at the centers of two N(2)O sites. In both cases, deprotonation of the hydrogen atoms of the phenolic OH groups occur except in the case of the Ni(II), Fe(III) and Cr(III) complexes. Electronic spectra and magnetic moments of the complexes indicate that the geometries of the metal centers are either octahedral or tetrahedral. The structures are consistent with the IR, UV-vis, ESR, (1)H NMR, mass spectra, and thermal gravimetric analysis (TGA/DTA) as well as conductivity and magnetic moment measurements.     

On the mechanism of electroreduction of sulphur-containing ligands induced by the electroreduction of transition metal cations

The large scale electrolysis of Zn(II), Cd(II), Hg(II), Cu(II), Ni(II), Co(II), Co(III), Fe(II), Mn(II), Cr(II), Cr(III), Bi(III), In(III) and Sb(III) at mercury electrodes in presence of mercaptoacetic acid, 3-mercaptopropionic acid, cysteine and thiourea was carried out and the products were investigated. In case of transition metal ions the catalytic reduction of organic compounds resulting in the formation of sulphide ions was found. There are two possible ways of the production of these ions: (i) consisting in the formation of a complex between transition metal ion and organic ligand which is subsequently, reduced, and (ii) direct electroreduction of organic compound on the electrode modifiied by the deposition of metal and metal sulphide. For both cases the mechanism of electroreduction was discussed.     

Adsorption behaviour of some metal complexes with ferron on Zeo-Karb-226: An atomic absorption spectrophotometric (AAS) study

Summary The adsorption behaviour of ten metal complexes Cr(III), Cr(VI), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and Pb(II) with ferron on Zeo-Karb-226 in the H⁺ form was investigated at eight different pH-values in order to develop a preconcentration technique for trace amounts of these elements in aqueous solution. The concentrations of the remaining unadsorbed metal ions were determined by atomic absorption spectrophotometry. Under the present experimental conditions, Cr(III) and Pb(II) can be quantitatively determined within the pH range 4–8, while for Cd(II), the optimum pH-range is 7–11. But at pH 11, more than 95% of Cu(II) and Co(II) can be extracted from aqueous solution. The suitability of the technique has been evaluated by analyzing cadmium in simulated water samples. The results indicate that as low as 5 g 1^–1 of CD can be recovered with more than 96% efficiency from 11 of simulated water solution.

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Adsorptionsverhalten einiger Metallkomplexe mit Ferron an Zeokarb-226: eine AAS-Untersuchung

Zusammenfassung Das Adsorptionsverhalten der Komplexe von Cr(III), Cr(VI), Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II) und Pb(II) mit Ferron an Zeokarb-226 in der H⁺-Form wurde bei acht verschiedenen pH-Werten untersucht, um eine Anreicherungsmethode für Spuren dieser Elemente zu entwickeln. Die Konzentrationen der verbliebenen nicht adsorbierten Metallionen wurden mit Hilfe der AAS bestimmt. Cr(III) und Pb(II) können im pH-Bereich 4–8 quantitativ erfaßt werden, während der optimale Bereich für Cd(II) bei pH 7–11 liegt. Bei pH 11 werden jedoch mehr als 95% Cu(II) und Co(II) aus der wäßrigen Lösung extrahiert. Der Nutzen des Verfahrens wurde durch Bestimmung von Cd(II) in simulierten Wasserproben erwiesen. Noch 5 g/l Cd können zu mehr als 96% aus 11 Wasserprobe wiedergefunden werden.

     

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.     

A new method for simultaneous determination of Co(II), Ni(II) and Pd(II) as morpholine-4-carbodithioate complex by SPME-HPLC-UV system

A new approach for the analysis of Co(II), Ni(II) and Pd(II) as morpholine-4-carbodithioate (MDTC) complexes in aqueous medium by using solid phase microextraction (SPME)-high performance liquid chromatography (HPLC)-UV has been developed. The method involves sorption of metal complexes on PDMS fiber from aqueous solution followed by desorption in the desorption chamber of SPME-HPLC interface using acetonitrile:water (60:40) as mobile phase. A good separation of metal complexes is achieved on C₁₈ column. The detection limits of Co(II), Ni(II) and Pd(II) are 0.17, 0.11 and 0.06 ng ml⁻¹, respectively. These can be determined by the proposed method without interference from other common metal ions such as Mo(VI), V(V), Ag(I), Sn(IV), Cd(II), Pb(II), Zn(II), Ag(I), Sn(II), Cr(III) and Cr(VI). The method was applied to the determination of these metals in different alloy samples and drinking water sample.     

Determination of Metal Ions in Natural Waters by Flame-AAS after Preconcentration on a 5-Amino-1,3,4-Thiadiazole-2-Thiol Modified Silica Gel.

ABSTRACT

5-amino-1,3,4-thiadiazole-2-thiol groups attached on a silica gel surface have been used for adsorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), Pb(II) and Zn(II) from aqueous solutions. The adsorption capacities for each metal ion were (in mmol.g^?1): Cd(II)= 0.35, Co(II)= 0.10, Cu(II)= 0.15, Fe(III)= 0.20, Hg(II)= 0.46, Ni(II)= 0.16, Pb(II)= 0.13 and Zn(II)= 0.15. The modified silica gel was applied in the preconcentration and quantification of trace level metal ions present in water samples (river, and bog water).