Cadmium Cations Research Articles

A Novel Aptasensor Based on Graphene/Graphite Carbon Nitride Nanocomposites for Cadmium Detection with High Selectivity and Sensitivity

Aptamers as new modes of detection have strong affinity and specificity for targets. A novel sensor was developed by constructing a composite system of specific aptamers and reduced graphene oxide (rGO)/graphitic carbon nitride (g-C3N4) (GCN) for detecting the cadmium cation. Attributed to the incorporation of rGO and aptamers with designed terminal groups as well as the delicate bonding of aptamers with g-C3N4, this electrochemical biosensor exhibited good sensitivity, specificity, reproducibility, and stability for Cd2+ detection. The linear calibration curves range from 1 nM to 1 μM and from 1 μM to 1 mM, and the limit of detection (LOD) was calculated to be 0.337 nM. The practical application of the proposed method was also verified in the real sample.

Separation of cations of heavy metalsfrom concentrated galvanic drains

When applying galvanic coatings, soluble salts of heavy metals such as iron, copper, nickel, zinc, cadmium, chromium and other metals are used, toxic cations enter the water, with subsequent migration to the biosphere. To date, many methods have been developed for cleaning galvanic sewage, which cannot be considered sufficiently effective. The joint sorption of divalent cations of copper, nickel and cadmium from concentrated aqueous solutions was investigated. Calculation and experimental methods were used to determine the separation conditions of the bivalent ion systems that differed and close in sorption properties on the aminophosphonic polyampholyte Purolite S950 in a natrium form. It is shown that the cadmium (II) cations can be isolated from solutions containing copper (II) or nickel (II) cations even at the height of the sorption layer of 0.13 m due to the difference in the defining characteristics of the cations. This layer height can be used not only in a chromatographic column, but also in a concentrating cartridge. Separation of the copper (II) and nickel (II) close to the sorption properties requires an absorbing layer of 0.76 m, which can only be used in a chromatographic column, but not for a concentrating cartridge. In this paper, the degrees of ion separation in various sorption conditions are calculated. The applicability of the conductometric method for controlling the ion exchange process is shown not only when the free cations are isolated from aqueous solutions but also bound to complexes.

Mitochondrial Morphology and Function of the Pancreatic β-Cells INS-1 Model upon Chronic Exposure to Sub-Lethal Cadmium Doses.

The impact of chronic cadmium exposure and slow accumulation on the occurrence and development of diabetes is controversial for human populations. Islets of Langerhans play a prominent role in the etiology of the disease, including by their ability to secrete insulin. Conversion of glucose increase into insulin secretion involves mitochondria. A rat model of pancreatic β-cells was exposed to largely sub-lethal levels of cadmium cations applied for the longest possible time. Cadmium entered cells at concentrations far below those inducing cell death and accumulated by factors reaching several hundred folds the basal level. The mitochondria reorganized in response to the challenge by favoring fission as measured by increased circularity at cadmium levels already ten-fold below the median lethal dose. However, the energy charge and respiratory flux devoted to adenosine triphosphate synthesis were only affected at the onset of cellular death. The present data indicate that mitochondria participate in the adaptation of β-cells to even a moderate cadmium burden without losing functionality, but their impairment in the long run may contribute to cellular dysfunction, when viability and β-cells mass are affected as observed in diabetes.

Removal of cadmium(II) cations from an aqueous solution with aminothiourea chitosan strengthened magnetic biochar

ABSTRACTAn aminothiourea chitosan modified magnetic biochar composite (TMBC) was prepared for the efficient removal of Cd(II) from wastewater. The synthesized materials were characterized, and the detailed adsorption mechanisms and thermodynamics were studied. The adsorption experiments revealed that TMBC had a higher affinity for Cd(II) than the magnetic biochar composite, raw biochar, and other carbon‐based adsorbents did. The Cd(II) adsorption process fit the pseudo‐second‐order kinetic model, and the maximum adsorption capacities on the basis of the Langmuir model were 93.72, 121.9, and 137.3 mg/g at 298, 308, and 318 K, respectively. The practical efficacy of the adsorbent was also tested with a real mine water. The metal‐ion‐loaded TMBC could be conveniently collected by a magnet and could be easily regenerated with adsorption efficiencies up to 84% after five adsorption–desorption cycles. The as‐prepared TMBC might be a promising adsorbent for the treatment of heavy‐metal‐ion‐contaminated water or highly mineralized mine water. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46239.

“Titanium Oxide-Clay” as Adsorbent and Photocatalysts for Wastewater Treatment

A novel composite based on Titanium oxide and clays hydrothermally was synthesized to be used as substrate in advanced treatment of wastewaters. The treatment consists of one single step process combining photocatalysis and adsorption. The composite’s crystalline structure is investigated by X-ray diffraction and FTIR, while atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to analyze the surface morphology. The adsorption capacity and photocatalytic properties of the material are tested on pollutants matrix containing dye (Methylene Blue) and heavy metal (cadmium cation). The results under optimized conditions indicate a good removal efficiency using this novel composite material.

Kinetics of the Reduction of Cadmium Sulfate by Thiourea Dioxide in an Aqueous Ammonia Solution upon the Metallization of Carbon Fiber

The kinetics of the decomposition of thiourea dioxide and the reduction of cadmium cations by thiourea dioxide in an aqueous ammonia solution are studied. The kinetic parameters of these reactions are calculated using experimental data, allowing us to adjust conditions for the synthesis of cadmium coatings on carbon fiber of grade UKN-M-12K. The presence of the metal crystalline phase on the fiber is confirmed by means of X-ray diffraction, and its amount is measured via atomic absorption spectroscopy.

A DFT study of the interaction between [Cd(H2O)3]2+ and monodentate O-, N-, and S-donor ligands: bond interaction analysis.

A series of B3LYP/6-311+G(d,p) calculations of the affinity of monodentate ligands for [Cd(H2O)3]2+ are performed. Three types of ligands containing O (phosphine oxide, lactam, amide, carboxylic acid, ester, ketone, aldehyde, ether, halohydrin, enol, furan), N (thiocyanate, amine, ammonia, azide), and S (thioester, thioketone, thiol, thiophene, disulfide) interacting atoms are investigated. The results show that phosphine oxide has the largest affinity for the cadmium cation due to the polarization of the P=O bond. As the P atom has a large atomic radius, the O atom can polarize the electronic cloud enhancing its amount of electronic charge and favoring the interaction with Cd2+. The affinity order found is phosphine oxide > thioester > lactam > amide > carboxylic acid > ester > thioketone > ketone > thiocyanate > amine > ammonia > aldehyde > ether > thiol > thiophene > enol > halohydrin > disulfide > azide > furan ligands. These results were also corroborated by the functional M06-2X. The electronic effects (resonance and induction) of neighboring groups of the interacting atom modulate the strength of metal-ligand binding. For almost all the O-donor ligands the electrostatic component has the same magnitude as the covalent term, while for the N- and S-donor ligands the covalent term is predominant. The polarization term accounts for twice the exchange term as part of the covalent component. The dispersion term varies less than 2kcal mol-1 for the complexes analyzed. The Pauli repulsion term is correlated with the metal ligand distance, increasing in the compounds with decreased metal-ligand bond length. The charge between the interacting atoms is also strongly correlated with both the interacting strength and the electrostatic interaction component. The natural bond orbital analysis highlights correlations of the bond order, and S and P contributions of the interacting metal-ligand orbital with the coordination strength. Graphical abstract The affinity of 20 monodentate ligands with different functional groups for the [Cd(H2O)3]2+ cation is calculated based on the interaction enthalpy and Gibbs free energy for the substitution of one water molecule from the fully hydrated cation. The affinity is correlated with geometric, electronic, and energetic parameters of the ligands and the complexes as well as with energy decomposition and natural bond order analyses results.

Polysaccharides as Effective Sorbents for Lead and Cadmium

Sorption of lead and cadmium cations from solutions of their salts on amorphous cellulose, potato starch, apple pectin, and chicory root inulin was studied. Sample preparation was performed in conditions (pH and stirring time and intensity) similar to those in the stomach and intestines of a typical person. The sorption properties of the studied polysaccharides with respect to both the individual heavy metals and their mixtures is variable. The sorption properties series are cellulose ≈ pectin < starch< inulin for Pb2+ and cellulose < pectin < starch ≈ inulin for Cd2+.

The Mixed-Metal Oxochromates(VI) Cd(HgI2)2(HgII)3O4(CrO4)2, Cd(HgII)4O4(CrO4) and Zn(HgII)4O4(CrO4)—Examples of the Different Crystal Chemistry within the Zinc Triad

The three mixed-metal oxochromates(VI) Cd(HgI2)2(HgII)3O4(CrO4)2, Cd(HgII)4O4(CrO4), and Zn(HgII)4O4(CrO4) were grown under hydrothermal conditions. Their crystal structures were determined from single-crystal X-ray diffraction data. The crystal-chemical features of the respective metal cations are characterised, with a linear coordination for mercury atoms in oxidation states +I and +II, octahedral coordination spheres for the divalent zinc and cadmium cations and a tetrahedral configuration of the oxochromate(VI) anions. In the crystal structures the formation of two subunits is apparent, viz. a mercury-oxygen network and a network of cadmium (zinc) cations that are directly bound to the oxochromate(VI) anions. An alternative description of the crystal structures based on oxygen-centred polyhedra is also given.

THIOCYANATE COMPLEXES OF d-METALS: INFLUENCE OF CONCENTRATION OF KNCS AND NH4Cl ON A TYPE OF COORDINATION OF SCN-IONS BY FTIR SPECTROMETRY

By IR spectrometry thiocyanates aqueous solutions of divalent cations of cadmium, mercury, nickel, manganese, iron, zinc and cobalt were studied. It was found that cadmium (II), mercury (II), nickel (II), iron (II) thiocyanate ions coordinated by type thiocyanate, zinc (II) − according to the type isothiocyanate; cobalt (II) and manganese (II) coordination mode change depending on the concentration of potassium thiocyanate in a solution. These results are consistent with the theory of hard and soft acids and bases. Co2+ ions are intermediate acids, so they can coordinate with SCN− into two types; Zn2+ ions, although they belong to intermediate acids but have a strong affinity to nitrogen atoms, so thiocyanate group coordinated through nitrogen with Zn2+. Cations Hg2+ and Cd2+ are typical soft acids, so only coordinated SCN− ions through sulfur (as a mild base). Mn2+ ions can coordinate SCN− by two types. The effect of additives of the ammonium chloride ions on thiocyanate ions (0.5 mol/l) coordination with cobalt (II) ions was studie. With the increasing concentration of ammonium chloride in a solution a change occurs of coordination type with thiocyanate to isothiocyanate. It has been suggested that the increase in the concentration of potassium thiocyanate leads to the increase in the proportion of Co(NCS)42− and reduce the proportion of «free» water (unrelated with ions in the solution). Therefore, SCN− ions in the case Mn2+ and Co2+ oriented so that the hydrophobic sulfur atoms are external ones.Forcitation:Matveichuk Yu.V., Rakhman′ko E.M. Thiocyanate complexes of d-metals: influence of concentration of KNCS and NH4Cl on a type of coordination of SCN− ions by FTIR spectrometry. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 7. P. 34-41.

Structural motifs in heteroleptic copper and cadmium selenites

Cu(II) cations in the presence of diamine ligands such as tetramethylethylendiamine (TMEDA) react with Na2SeO3 to produce the heteroleptic selenite copper compound of formula [Cu3(TMEDA)3(SeO3)2(H2O)4](NO3)2. In the cationic moiety two copper atoms are linked by two selenite anions through the O–Se–O bridge. One of the two bridging selenite anion coordinates to a third copper atom through the third oxygen atom. Reaction of Cd(CH3COO)2·2H2O with Na2SeO3 in the presence of ligand with softer character such as thiourea [(NH2)2CS; tu] or selenourea [(NH2)2CSe; tu] in aqueous solution afforded the complex [{Cd(tu)2SeO3}2], whose structure has been elucidated by X-ray diffraction analysis. It is the first reported example of a molecular cadmium selenite complex. Two cadmium cations stabilized by the coordination of four ancillary thiourea soft ligands, are linked together by two bridging selenite ions through O and O–Se–O bridges. A comparison between the coordination mode of the selenite ion in those cadmium and copper complexes and in inorganic extended CdSeO3 and hydrated CuSeO3 phases is also reported.

Cadmium impact, accumulation and detection in poplar callus cells.

Effect of cadmium cations and their interaction with silicon cations was determined in poplar calli and expressed as changes in callus growth, cell viability and cadmium cation accumulation. Cell viability throughout culture versus cadmium cation accumulation in cells is discussed. At the same time, the study sought appropriate methods for cadmium cation detection in callus cells and also in experiments with low plant material (e.g. protoplasts). Cadmium cations were determined by atomic absorption spectroscopy and using fluorescence microscopy with a specific cadmium cation fluorescent dye. The detection of cadmium cations in callus cells by the latter method appears suitable because the callus cells are surrounded by primary cell walls without auto-fluorescence and these values fit well with atomic absorption spectroscopy quantification. However, the visualisation method has some limits discussed below.

The synthesis, activation and characterization of charcoal powder for the removal of methylene blue and cadmium from wastewater

Charcoal prepared from biomass, wastes of the local forest (tree branches), activated with NaOH solution and with Degussa P25 (TiO2) was used as adsorbent and photocatalyst for the removal of cadmium cations and methylene blue from wastewater. These materials were characterized by using atomic force microscopy for roughness surface. The energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis indicate the existence of nano TiO2 on the charcoal surface. Additionally, the FT-IR spectroscopy measurements indicate that the alkali treatment develops hydroxyl groups on charcoal surface which could adsorb methylene blue, heavy metals and other pollutants via the synergistic effect. The activities of the charcoal (BC), activated charcoal (BCA) and BCA/TiO2 mixture (BCA-D) depend on the contact time, adsorbent dosage and pH. The adsorption kinetic data were tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The kinetic studies showed that the adsorption is followed by the pseudo-second-order reaction with regard to the intraparticle diffusion rate kinetics.

Complex-forming and ion-selective properties of bis(2-diphenylphosphorylalkyl)phenyl ethers of ethylene glycols. Crystal structures of cadmium complexes

New complexes of cadmium iodide with 1,3-bis[2-(diphenylphosphoryl)phenoxy]propane [CdL0I2], 1,2-bis[2-(diphenylphosphorylethyl)phenoxy]ethane [CdL1, 2I2], and 1,8-bis[2-(diphenylphosphorylethyl) phenoxy]-3,6-dioxaoctane [CdL3, 2I2] are synthesized and their IR spectra and crystal structures are studied. Electroanalytical characteristics of membranes of ion-selective electrodes based on L0, L1, 2, L3, 2, and known crown ethers are compared for cations of alkali, alkaline-earth, and transition metals. Ligand L3, 2 is the first podand with terminal diphenylphosphoryl fragments to exhibit selectivity with respect to the cadmium cation.

Surface enhanced Raman scattering by a new derivative of acridine in solutions of colloidal silver

A new derivative of acridine, 4,5-bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA), which is a selective fluorophore relative to cadmium cations, is studied by the method of surface-enhanced Raman scattering (SERS). The SERS spectra of BHIA adsorbed on colloidal silver particles exhibit a high intensity and temporal stability of the signal. An assignment of the bands present in the studied spectral range is given. The dependence of the SERS spectra of BHIA on the solution’s pH reveals that the ligand can exist on the surface in protonated and deprotonated forms. The stability of the deprotonated form on the surface suggests that the ligand interacts with the surface by means of a conjugated π-system of aromatic rings. The addition of the salt of halide ions to the solution has a significant influence on the SERS spectrum. This effect is due to the displacement of the adsorbate molecules from the first monolayer, which is accompanied by the transition of BHIA from the chemi- to the physisorbed form.

Nonuniform Excitonic Charge Distribution Enhances Exciton-Phonon Coupling in ZnSe/CdSe Alloyed Quantum Dots.

Zinc to cadmium cation exchange of ZnSe quantum dots has been used to produce a series of alloyed Zn1-xCdxSe quantum dots. As x increases and the lowest-energy exciton shifts to the red, the peak initially broadens and then sharpens as x approaches 1. Resonance Raman spectra obtained with excitation near the lowest excitonic absorption peak show a gradual shift of the longitudinal optical phonon peak from 251 cm-1 in pure ZnSe to 210 cm-1 in nearly pure CdSe with strong broadening at intermediate compositions. The LO overtone to fundamental intensity ratio, a rough gauge of exciton-phonon coupling strength, increases considerably for intermediate compositions compared with those of either pure ZnSe or pure CdSe. The results indicate that partial localization of the hole in locally Cd-rich regions of the alloyed particles increases the strengths of local internal electric fields, increasing the coupling between the exciton and polar optical phonons.

MODELING EQUILIBRIUM DATA FOR Cd (II) ADSORPTION BY PEAT USING NON-LINEAR REGRESSION ANALYSIS

The Romanian peat was used as low-cost adsorbent to remove Cd(II) ions from aqueous solutions. The cadmium adsorption capacity of the peat was studied as a function of the solution pH (3-5.5) and temperature (293 333 K). Adsorption capacity was found to increase with the pH increasing and temperature decreasing and attained a maximum value of 27.9 mg/g at pH = 5 0.1 (acetate buffer) and 293 K. In addition, various thermodynamic parameters such as free energy change (.G0), enthalpy change (.H0), entropy change (.S0) along with isosteric heat of sorption (.Hx) were calculated. The adsorption of Cd (II) ions by peat was found to be a spontaneous and exothermic process, which is governed by electrostatic interactions (physisorption). FT-IR analysis of the peat before and after Cd (II) sorption suggests electrostatic attraction between cadmium cations and negatively charged COO- groups present on the peat surface.

Impact of cadmium and phosphate ions on the hematite nanorings formation

It has been suggested that the addition of divalent metal cations during the hydrothermal synthesis of hematite (α-Fe2O3) in the presence of phosphate ions has a strong impact on the hematite morphology, crystal growth and dissolution (Gotić et al., J. Mol. Struct. 993 (2011) 167). In this work, the same system was modified with divalent cadmium ions and the impacts of cadmium and phosphate ions on the hematite nanorings formation have been studied. It has been found that formed hematite and akaganeite (β-FeOOH) precipitates did not contain any trace of cadmium impurities. On the contrary, the modification with divalent cadmium cations changes the PO43−/Fe3+ molar ratio in the system. Upon the addition of cadmium ions the PO43−/Fe3+ molar ratio changes from 0.036 in a pure system to 0.051 in the cadmium modified system. The relative increase of phosphate concentration at early stage of precipitation induced the change of spindle to spherical morphology and formation of the poorly crystallised akaganeite-like phase. The appearance of akaganeite-like phase directly correlated with the delay in the crystallisation of hematite. Besides, the relative increase of phosphate concentration has the prevailing effect for the change of spindle to pseudosphere and nanotube to nanoring particle morphologies.

Removal of lead (II) and cadmium (II) cations from water using surface‐modified graphene

With its unique structure, graphene exhibits a number of outstanding mechanical, optical, and electronic properties, thus promising several potential applications. In the current work, graphene sheets were prepared from graphite and surface‐modified via an acid treatment. The synthesized material physicochemical properties were assessed using X‐ray diffraction, nitrogen adsorption and BET analysis, transmission electron microscopy, and Raman as well as X‐ray photoelectron spectroscopy techniques. The ability of the surface‐modified graphene in the adsorptive elimination of Pb(II) and Cd(II) cations from aqueous solutions was investigated batchwise under numerous experimental conditions. A pseudo‐second order kinetic model described adequately the adsorption kinetic profiles. The adsorption isotherms were compared to the Langmuir and Freundlich models. It was found that for both heavy metal cations, adsorption isotherms were reasonably described by Langmuir model equation. Maximum adsorption capacities reached 0.946 and 1.779 mmol ion/g for Pb(II) and Cd(II), respectively.

Construction of coordination polymers based on bis-pyridyl-bis-amide and dicarboxylate ligands

The synthesis, structures and properties of eight coordination polymers {[Zn(L1)(oba)]·2H2O}n [L1=N,N′-di(4-pyridyl)adipoamide; H2oba=4,4′-oxybis(benzoic acid)], 1, {[Zn(L1)(sda)]·2H2O}n (H2sda=4,4′-sulfonyldibenzoic acid), 2, [Cd(4-apy)2(oba)]n (4-apy=4-aminopyridine), 3, [Cd(oba)(H2O)2]n, 4, {[M(L2)(1,4-pda)(H2O)2]·2H2O}n, (M=Ni, 5; Co, 6; L2=N,N′-di(3-pyridyl)suberoamide; 1,4-H2pda=1,4-phenylenediacetic acid), {[Cd(L2)(1,4-pda)]·2H2O}n, 7, and [Cu(L2)(1,4-bdc)(H2O)2]n (1,4-H2bdc=1,4-benzenedicarboxylic acid), 8, are reported. Complex 1 is a 1D→2D polycatenane derived from the helical channels, and the 2D layers are further mutually interdigitated. The 1D looped chains of 2 are interlinked through OH⋯O hydrogen bonds and the 1D zigzag chains of 3 are interlinked through NH⋯O hydrogen bonds, resulting in 2D supramolecular structures, whereas the cadmium(II) cations of 4 are linked by the oba2− ligands and water molecules to form a 3D network with the dia topology. The structures of complexes 5, 6 and 8 can be simplified as 4-connected 2D nets with the sql topology and complex 7 exhibits a double layer, showing a 3,5-connected net with the (42.67.8)(42.6)-3,5L2 topology. The structural types of the L1-based divalent coordination polymers are subject to the change of the angular dicarboxylate ligands, whereas the structural difference in 5–7 based on 1,4-pda2− and L2 ligand can be ascribed to the size of the central metal atom. Their thermal, luminescent and catalytic properties are also discussed.