Biosorption of cadmium (II) and lead (II) from aqueous solution using exopolysaccharide and biomass produced by Colletotrichum sp.

The biosorption of Cd(II) and Pb(II) ions on biomass and exopolysaccharide (EPS) produced by Colletotrichum sp. fungus has been investigated as a function of contact time, initial pH, initial metal ion concentration, and initial adsorbent concentration in a batch system. Adsorption equilibrium was described by Freundlich and Langmuir isotherms. Adsorption was characterized through granulometry, SEM and EDX analysis. Then, studies were performed to regenerate the adsorbent. Biosorption of metals by biomass and EPS were best described by the Langmuir and Freundlich isotherm, respectively. Results of thermodynamic investigations showed that adsorption reactions were spontaneous (ΔG° < 0), exothermal, and mainly physical. The EPS was able to remove 79 and 98% of cadmium and lead, respectively, and the biomass removed 85 and 84% of cadmium and lead, respectively, in a solution with initial concentration 100 mg L-1, and the four adsorption-desorption cycles of all adsorbents showed up with great regenerative capacity and relative stability after these four cycles, the high potential of these biological materials in sorption has been shown. © 2013 Copyright Balaban Desalination Publications.

A new 3D cadmium(II) coordination polymer having mu(4)-oxalato, mu-aquo and mu-chlorido bridges: crystal structure, solid state fluorescence and thermal behavior

A new 3D cadmium(II) coordination polymer, Cd(C2O4)(0.5)Cl(H2O)](n) (1) has been synthesized from a mixture of CdCl2. H2O and (NH4)(2)C2O4 in a slightly acidic pH. Its molecular structure was determined by single crystal X-ray diffraction which reveals that the new polymeric structure consists of simultaneous mu(4)-oxalato, mu-aquo, and mu-chlorido bridges between the metal centers, embedded in distorted pentagonal bipyramidal geometries. On thermal analysis compound exhibits high thermal stability up to 330 degrees C. Compound 1 also exhibits strong fluorescent emission. (c) 2013 Elsevier B.V. All rights reserved.

A Dinuclear Cadmium(II) Schiff Base Thiocyanato Complex: Crystal Structure and Fluorescence

A new dinuclear cadmium(II) complex, Cd(L)(NCS)](2) (1) has been synthesized using a potentially tetradentate Schiff base ligand HL, 2-((E)-(2-(diethylamino) ethylimino) methyl)-6-methoxyphenol, obtained by the condensation of 2-diethylaminoethylamine and o-vanillin, and characterized by different physicochemical techniques. Crystal structure of the title complex was unambiguously established by single crystal X-ray diffraction which reveals that metal centers are connected by bridging phenolato and chelating methoxy oxygen atoms of the coordinating Schiff bases and embedded in severely distorted octahedral geometries. Fluorescence properties of the ligand and its complex, studied at room temperature indicate that later may serve as strong fluorescent

Biosorption of Cd2+, Cu2+, Ni2+ and Zn2+ ions from aqueous solutions by pretreated biomass of brown algae

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+.

Biosorption of Cd2+, Cu2+, Ni2+ and Zn2+ ions from aqueous solutions by pretreated biomass of brown algae

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+. The experimental data have been analyzed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results showed that the biosorption equilibrium was well described by both the Langmuir and Redlich-Peterson isotherms.

Diacetatobis[2-(2-furyl)-1H-imidazo[4,5-f]-[1,10]phenanthroline]cadmium(II)

In the title complex, [Cd(C2H3O2)(2)(C17H10N4O)(2)], the central Cd-II ion (site symmetry 2) shows an uncommon eight-coordinate CdN4O4 coordination geometry arising from two N,N-chelating 2-(2-furyl)-1H-imidazo[4,5-f]-1,10-phenanthro-line molecules and two O, O-bidentate acetate anions.

Extraction and separation of cadmium(II), iron(III), zinc(II), and europium(III) by Cyanex302 solutions using hollow fiber membrane modules

The mass transfer behaviors of Cd(II), Fe(III), Zn(II), and Eu(III) in sulfuric acid solution using microporous hollow fiber membrane (HFM) containing bis(2,4,4-trimethylpentyl)monothiophosphinic acid (commercial name Cyanex302) were investigated in this paper. The experimental results showed that the values of the mass transfer coefficients (K-w) decreased with an increase of H+ concentration and increased with an increase of extractant Cyanex302 concentration. The mass transfer resistance of Eu3+ was the largest because K-w value of Eu3+ was the smallest. The order of mass transfer rate of metal ions at low pH was Cd > Zn > Fe > Eu. Mixtures of Zn2+ and Eu3+ or of Zn2+ and Cd2+ were well separated in a counter-current circulation experiment using two modules connected in series at different initial acidity and concentration ratio. These results indicate that a hollow fiber membrane extractor is capable of separating the mixture compounds by controlling the acidity of the aqueous solution and by exploiting different mass transfer kinetics. The interfacial activity of Cyanex302 in sulfuric acid solution was measured and interfacial parameters were obtained according to Gibbs adsorption equation.

Synergistic extraction of zinc(II) and cadmium(II) with mixtures of primary amine N1923 and neutral organophosphorous derivatives

Synergistic extraction of zinc(IT) and cadmium(11) from hydrochloric acid solution with primary amine N1923 and neutral organophosphorus derivatives Cyanex 923 and Cyanex 925 is the focus of this paper. Extraction mechanisms are discussed as well as how the acidity of the aqueous phase, the composition of the organic phase, and the experimental temperature affect the rates of extraction of metal ions. Differences between synergistic efficiency of Zn(II) and Cd(II) with mixtures of primary amines N1923 and either Cyanex 923 or Cyanex 925 are observed. The equilibrium constants, the composition, and the formation constants of the extracted complexes as well as the values of the thermodynamic functions are calculated. According to the synergy coefficient formula, the synergy effect on the extraction of Zn(II) is in the following order:N1923 + Cyanex 925 > N1923 + Cyanex 923 This order is reversed in the case of cadmium(II). For the same synergistic system, the extraction rate follows the order: Zn(II) > Cd(II). Furthermore, the stereochemical structures of the various extractants and their effect on metal ion extraction rate are also investigated.

Extraction of zinc(II) and cadmium(II) by using mixtures of primary amine N1923 and organophosphorus acids

The extraction of zinc(II) and cadmium(II) from a chloride medium by mixtures of primary amine N1923 and organophosphorus acids [di-(2-ethylhexyl)-phosphoric acid, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH/EHP), isopropyl phosphonic acid 1-hexyl-4-ethyloctyl ester, bis(2,4,4-trimethylpentyl) phosphinic acid, bis(2,4,4-trimethylpentyl) monothiophosphinic acid, and bis(2,4,4-trimethylpentyl) dithiophosphinic acid] has been studied in the present paper. Results show that only the mixtures of N1923 + HEH/EHP and N1923 + Cyanex272 have synergistic effects on zinc(II), but the other mixtures have no evident synergistic effects. All six mixtures have no evident synergistic effects on cadmium(H). A possible explanation of the different extraction abilities is given based on the structure of the extractants. Furthermore, the possibilities of separating zinc(II) and cadmium(II) with these mixtures are investigated according to the extractabilities. It is possible to separate Zn2+ from bulk cadmium with N1923 and HEH/EHP mixtures and separate Cd2+ from bulk zinc with N1923 and Cyanex301 mixtures.

Dichloridobis[N-(2-pyridylmethyl)-benzamide-kappa N-2,O]cadmium(II)

In the title compound, [CdCl2(C13H12N2O)(2)], the Cd-II ion is situated on an inversion centre, coordinated by two 0 atoms [Cd-O=2.3878 (17) angstrom] and two N atoms [Cd-N = 2.3404 (15) angstrom] from two N-(2-pyridylmethyl)benzamide ligands, and two Cl atoms [Cd-Cl = 2.5566 (6) angstrom], in a distorted octahedral geometry. In the crystal structure, intermolecular N-H center dot center dot center dot Cl hydrogen bonds [N center dot center dot center dot Cl = 3.1705 (18) angstrom] and pi-pi interactions, with a distance of 3.868 (3) angstrom between the centroids of the phenyl and pyridyl rings of neighbouring molecules, lead to the formation of two-dimensional layers parallel to the bc plane.

cis-Dichloridobis(1,10-phenanthroline-kappa N-2,N ')-cadmium(II) hemihydrate

The title compound, [ CdCl2( C12H8N2)(2)]center dot 0.5H(2)O, crystallizes with two independent complex molecules and one water molecule in the asymmetric unit. The Cd atoms in both independent complexes display a distorted octahedral coordination geometry formed by four N atoms from two phenanthroline ligands and two Cl atoms. In the crystal structure, pi-pi stacking interactions link complexes in two symmetry- independent ladders parallel to the c axis. Intermolecular O-H center dot center dot center dot Cl hydrogen bonds stabilize the crystal packing.

The effect of co-precipitation on cadmium(II) adsorption on hydrous aluminium(III) hydroxide in the presence of a range of chelates

The adsorption of cadmium(II) on freshly precipitated aluminium(III) hydroxide in the presence of a range of chelates has been investigated. By precipitating the metal, chelate and adsorbent together it is possible to change the pH variation of the metal-complex adsorption from anionic, ligand-like, binding to cationic binding. This is a general phenomenon and is explained by the formation of a ternary Al-O-Cd-L surface species. As a consequence of the preparation method, the pH edge is found to shift to lower pH values in the presence of the chelate which gives rise to an apparent increase in adsorption of Cd2+. This increase is, in general, most pronounced at [chelate] / [metal] > 1. Computer modelling shows that the observed trends result from the competition between Al-O-Cd-L and Al-L for the available aluminium( III) binding sites. The enhanced adsorption in the presence of phenylenediaminetetraacetate is anomalous since it is observed at a [ chelate] / [metal] approximate to 0.1 and cannot be interpreted by the simple competition model.

Dichloridobis(picolinohydrazide)cadmium(II)

The title compound, [CdCl2(C6H7N3O)(2)], was obtained unintentionally as a product of an attempted reaction of CdCl2 center dot 2.5H(2)O and picolinic acid hydrazide, in order to obtain a cadmium(II) complex analogous to a 15-metallacrown-5 complex of the formula [MCu5L5]X-n, with M = a central metal ion, L = picolinic acid hydrazide and X = Cl- , but with cadmium the only metal present. The coordination geometry around the Cd-II atom can be considered as distorted octahedral, with two bidentate picolinic acid hydrazide ligands, each coordinating through their carbonyl O atom and amino N atom, and two chloride anions. In the crystal structure, intermolecular N-H center dot center dot center dot Cl and N-H center dot center dot center dot N hydrogen bonds link the molecules into a two-dimensional network parallel to the ( 100) plane. The pyridine rings of adjacent networks are involved in pi-pi stacking interactions, the minimum distance between the ring centroids being 3.693 (2) angstrom.