Metal Ions Cd Research Articles

Removal of metal ions Cd(II), Cr(VI) and Ni(II) from aqueous solution using an organic aerogel and carbon aerogel obtained by acid catalysis

In this work, we evaluated the adsorption capacity of the metal ions Cd(II), Cr(VI) and Ni(II) from aqueous solution of an organic aerogel, a carbon aerogel and a commercial activated carbon. Aerogel (Ae) was obtained by acid catalysis using HCl, achieving a quick synthesis, then, a process of carbonization to obtain the carbon aerogel (CAe) was performed. Structural, textural and chemical parameters of the porous solids obtained were characterized by different experimental techniques: scanning electron microscopy (SEM), adsorption isotherms of N2 at 77 K and CO2 at 273 K, Boehm titrations and pHPZC determination. The three adsorbents were employed in simple adsorption systems of Ni(II), Cd(II) and Cr(VI) from aqueous solution. It was determined that the synthesized aerogel is the material that performed the highest adsorption capacity of the three metal ions: Ni (32.2 mg g–1) Cd (18.6 mg g–1) and Cr (35.5 mg g–1).

Effect of Dispersibility of Natural Sorbents on Their Sorption Activity for Cd(II), Pb(II), and Cu(II) Ions

The effect of the degree of dispersion of sorbent particles derived from natural minerals (vermiculite and perlite) on their sorption properties towards heavy metal ions Cd(II),Cu(II), and Pb(II) is studied. The particle sizes of the sorbents vary in the range from submicrons to nanometers (from 250 μm to 100 nm), using a range of dispersion methods (grinding using centrifuge and planetary ball mills),which result in a reduction of the particle size by 1.5–100 times. It is found that the sorption of the examined metal ions on the surface of all the substates can be described by the Langmuir absorption model, regardless of the degree of sorbent dispersion. The low values of the heat of the sorption for ions studied indicate the physical nature of sorption. An increase in the dispersion degree of the sorbents contributed to a significant increase in the sorption activity of dispersed particles of vermiculite and perlite towards to the ions studied (up to 2-fold increase in the sorption degree values). The optimization of the sorption conditions made it possible to achieve high sorption efficiency with the sorption degree ~99.9% towards Cd(II), Cu(II), and Pb(II) ions at a 10-4 mol/L ion concentration and close to neutral conditions at ambient temperature.

Kinetic and thermodynamic studies of sorption of lead and cadmium from aqueous solution by <i>Moringa oleifera</i> pod wastes

Equilibrium sorption of Pb(II) and Cd(II) from aqueous solution by Moringa oleifera pods waste was conducted under batch conditions. Effects of operating variables such as initial concentration, contact time, adsorbent dose, pH and temperature on the sorption of these heavy metals have been studied. The optimum pH for the adsorption was found to be 5.0 and the adsorption process was found to be exothermic for both metal ions. The competitive adsorption characteristics of the combinations of binary mixtures of aqueous metal ion species, Pb2+ (aq) and Cd2+ (aq), on the adsorbent were also investigated. The Langmuir, Freundlich, Temkin and Dubinin Radushkevich adsorption isotherm models were used to analyse the equilibrium data. Kinetics data evaluation showed that the adsorption followed a pseudo-second order model. A solution of 0.05 M HCl has been found to be sufficient for the regeneration of spent adsorbent with up to 90% recovery for the two metal ions.

Highly Permeable Monolith-based Multichannel In-Tip Microextraction Apparatus for Simultaneous Field Sample Preparation of Pesticides and Heavy Metal Ions in Environmental Waters.

A portable multichannel in-tip microextraction-based field sample preparation (FSP) apparatus was developed using polymer-based monoliths as an extraction phase. The construction of the FSP device is quite facile and convenient. More specifically, according to the chemical properties of studied analytes, functional-rich and high-permeability monoliths were in situ synthesized in pipet tips. After that, three tips containing the sorbents were mounted to three syringes, which were connected to a screw motor employed to drive the syringes and accurately regulate the flow rates in the adsorption and desorption stages. Because of the multifunction groups in the monoliths, the sorbents displayed satisfactory coextraction performance for pesticides (carbamates and triazoles) and heavy metal ions (Cd2+, Pb2+, and Cu2+) under the optimized conditions. The practicability of the proposed apparatus was demonstrated by the quick and simultaneous FSP of studied analytes in various environmental waters and combined with high-performance liquid chromatography/diode-array detection (for pesticides) and atomic absorption spectrometry (for metal ion) analysis. The results indicated that the limits of detection for the pesticides and metal ions were in the range of 0.36 to 1.2 ng/L and 0.061 to 0.40 ng/L, respectively, with ideal coefficients of determination. Furthermore, the results obtained with the constructed device were quite comparable to those obtained with the traditional laboratory extraction process, which demonstrated that the newly developed apparatus possesses the expected application in the high-throughput FSP of pesticides and heavy metal ions in water samples.

Triplet of cysteines – Coordinational riddle?

Polythiol binding of metal ions plays crucial role in the proper functioning of cysteine-rich proteins that are responsible for metal homeostasis and defending processes against metal toxicity (including heavy metals detoxification). The coordination properties of cysteine residues involved in specific sequencional patterns in proteins (like those present in e.g. metallothioneins) are interesting not only from a chemical point of view but may also lead to a better understanding of the purpose and allocation of metal ions in various biomolecules. In this study, the interaction of Zn2+, Cd2+ and Ni2+ ions with four peptides containing cysteine triplet motif were studied by potentiometric and spectroscopic methods. The main goal of this research was to answer the question how effectively three thiols, each being next to other, are able to bind single metal ion. Two of peptides contain additional, fourth cysteine residue, separated from triplet by two and three other amino acid residues. As results show, all three cysteine residues in the CCC motif are able to participate in the coordination of the metal ion (Cd2+, Zn2+). Except cysteine thiol groups, amide nitrogen atoms are also involved in the coordination of Ni2+.

A highly sensitive fluorescent sensor for Cd2+ and Zn2+ based on diarylethene with a pyrene unit.

A novel multifunctional diarylethene fluorescence sensor 1O containing pyrene unit was designed and synthesized. The photochromism and fluorescence photoswitching properties of this diarylethene were studied in detail by irradiation of UV/Vis lights and response of metal ions in acetonitrile solution. Diarylethene fluorescence sensor 1O has high selectivity and sensitivity for the detections of Cd2+ and Zn2+. The limit of detections (LODs) for Cd2+ and Zn2+ were determined to be 1.85 × 10-9 mol L-1 and 7.68 × 10-9 mol L-1, respectively. The binding constants (Ka) of 1O with Cd2+ and Zn2+ in acetonitrile solution were calculated to be 5.8 × 104 mol-1 L and 6.0 × 104 mol-1 L, respectively. The compound 1O responded to the metal ions (Cd2+/Zn2+) to form complexations with 1 : 1 stoichiometry which were verified by Job's plot and MS analysis, respectively. In addition, the fluorescence sensor 1O has been successfully applied to the detection of Cd2+ and Zn2+ in real water samples and processed into test strips for on-site analysis and testing.

Highly efficient extraction/separation of Cr (VI) by a new family of hydrophobic deep eutectic solvents.

Highly efficient and selective separation of Cr (VI) is great of importance in environmental pollution control. In this study, a novel family of hydrophobic DESs has been designed and synthesized by mixing parabens and quaternary ammonium, and then used to extract heavy metal Cr (VI) from water phase and the content of Cr (VI) is measured by 1,5-diphenylcarbazide spectrophotometry. It is found that the hydrophobic DESs exhibit excellent extraction performance towards Cr (VI). At the 1:1 M ratio of DES to Cr (VI), the extraction capacity is as high as 66.7 mg g-1, the extraction efficiency is greater than 90% for ultra-trace Cr (VI) (0.51 μg L-1), and the preconcentration factor is up to 700. When the concentration of coexisting metal ions (Cd2+, Cu2+) and organic compounds ((C6H10O5)n, C6H12O6·H2O) is 2000 times that of Cr (VI), the extraction efficiency is still above 90%. Compared with ionic liquid extractants, the preparation process of DES is very simple, the atomic utilization rate is 100%, and no waste is produced. These hydrophobic DESs have been used to separate and enrich Cr (VI) from actual water samples with satisfactory recoveries. The possible extraction mechanism is investigated by FT-IR and 1H NMR.

Effect of Cadmium in Biosorption of Lead by Lengkeng Seed and Shell (Euphoria logan lour)

In this study, the effect of of Cd(II) in biosorption of Pb(II) by lengkeng seed and sheel from a binary metal mixture was studied and compared with the single metal ion situation and other way. The purpose studied by the metal ion competition in the solution is to know the effect and the absorption capacity of one type of metal ion in a solution containing several metal ions inside which will be applied to the waste. The optimum conditions used were for Pb at pH 3 and Cd at pH 5 with a particle size of 250μm. The results showed a decrease in the absorption of Pb metal ions reached 42.14% (for lengkeng sheel) and 57.07% (for lengkeng seed). And decrease of Cd metal ion to 68,11% for seed and 64,77% for lengkeng shell.

DFT study of the application of polymers cellulose and cellulose acetate for adsorption of metal ions (Cd2+, Cu2+ and Cr3+) potentially toxic

In this work, the functional density theory calculations were performed to investigate the interaction mechanism (adsorption) of Cu2+, Cr3+ and Cd2+ metal ions in cellulose (CE) and cellulose acetate (AC). After the optimization of the structures at their energy minima, the following analyses were performed: molecular electrostatic potential (MEPs), reactivity indexes, frontier molecular orbitals (FMOs), structural parameters, interaction energy and QTAIM analysis. The study of MEPs, FMOs and reactivity indexes showed that it is possible to predict the site of interaction. Structural analyses have proven that the interactions occur. The calculated electron interaction energies showed that all ions interact with the matrix of CE and AC, and among them, the Cr3+ ion was the one that interacted most effectively. Finally, the QTAIM analysis allowed to characterize the nature of the interaction, in which the interactions of cellulose acetate-Cr3+ and cellulose-Cu2+ presented electrostatic character, and the other interactions were partially covalent.

Imobilisasi kulit Lengkeng (euphoria longan lour) terhadap penyerapan ion logam Kadmium

The use of longan skin biosorbents has been shown to reduce environmental pollution caused by heavy metals. Because it has an active site and its facial pores can support the absorption process, it is inexpensive and environmentally friendly. However, the ability of longan skin in absorption has several limitations such as particles that are lightweight, easily damaged and of low specific gravity. To overcome this, various methods have been carried out, one of which is the immobilization of sodium silica. The biosorption method used was the bath method. The results of this study, optimum absorption of Cd metal ions occurred at a concentration of 250 ppm, with a contact time of 120 minutes and a speed of 250 rpm.

Synthesis, Spectral and Antimicrobial Investigation of 2-(Naphthalenel-ylamino)-2- Phenylacetonitrile and 1, 10-Phenanthroline with Five Divalent Transition Metal Ions

Five new mixed ligand metal complexes have been synthesized by the reaction of divalent transition metal ions (Hg, Ni, Zn, Cu and Cd) with 2-(naphthalen-l-ylamino)-2-phenylacetonitrile (L1 ) and 1,10-phenanthroline (L2). The coordination likelihood of the two ligands toward metal ions has been suggested in the light of elemental analysis, UV-Vis spectra, FTIR, 1H-NMR, flam atomic absorption, molar conductance and magnetic studies. Results data suggest that the octahedral geometry for all the prepared complexes. Antibacterial examination of synthesized complexes in vitro was performed against four bacterias. Firstly, Gram-negative bacteria namely, Pseudomonas aerugin and Escherichia. Secondly, Gram-positive bacteria namely, Bacillus subtilis, Staphylococcuaurouss. Results data exhibit that the synthesized complexes exhibited more biological activity than tetracycline pharmaceutical.

Adsorption of cadmium by a high-capacity adsorbent composed of silicate-titanate nanotubes embedded in hydrogel chitosan beads

ABSTRACT In this study, we developed a nanoparticle-based mesoporous composite that consisted of silicate-titanate nanotubes (STNTs) supported in hydrogel chitosan beads (STNTs-Ch beads) and was studied for Cd2+ adsorption. By using Fourier-transform infrared spectroscopy, transmission and scanning electron microscopy coupled to an energy-dispersive X-ray spectrometer, we could determine that the hollow STNTs were highly dispersed in the walls of the hollow beads. The dispersion was attributed to the effect of pH when the composite was prepared and we observed a non-interaction between STNTs and chitosan. The adsorption studies of Cd2+ showed that the kinetic rate (k 2) increased 3-fold and that the diffusion rate (K d) increased 2-fold after the embedment. Moreover, the maximum capacity of adsorption of STNTs-Ch beads was 2.3 times higher than that of STNTs alone. The treatment of a synthetic Cd2+ solution and a real leachate in continuous mode showed two phases in which it was observed higher removed fractions of transition metal ions (Cd2+, Co2+, Ni2+, Zn2+ and Cu2+) and the post-transition metal ion Pb2+, in comparison to the removed fractions of alkali and alkali-earth metal ions (Ca2+, K+, Mg2+). The composite was successfully reused four times when adsorbing Cd2+, saving three times the needed amounts of TiO2, SiO2 and chitosan for the production of the material. This composite was produced in a simple way and shows the potential for wastewater treatment.

Large scale fabrication of disposable carbon cloth electrochemical sensors for simultaneous determination of heavy metal ion

A portable electrode with approachable, available and simple processing is of great significance for the effective detection on-site in the practical situation. This work reported a new type of disposable carbon cloth working electrode (CCE), which was fabricated in large scale only through simple pretreatment without complex modification, and used for on-site detection of heavy metal ions Cd2+ and Pb2+ by differential pulse anodic stripping voltammetry (DPASV). The portable electrodes showed a wide detection range and the low detection limits, as well as the successful application for the simultaneous detection of Cd2+ and Pb2+ in real samples without mutual interference or interference from other ions. Better yet, the novel disposable electrode exhibited unique advantages of convenience, portability, reliable, low-cost and potential of mass production compared to conventional glassy carbon electrode (GCE), which may be an alternative advantageous choice for practical on-site detection.

SIMULTANEOUS EFFECTS OF Cd(II) AND Pb(II) IONS AND γ-IRRADIATION ON STABILITY OF Spirulina platensis

Effect of toxic metal ions Cd(II) and Pb(II) on cyanobacterium (blue-green algae) Spirulina platensis intact cells have been studied with optical and differential scanning microcalorimetry (DSC) methods after 7.2 kGy 137 Cs gamma irradiation and without irradiation. It is shown that the addition of metal ions causes a decrease in optical absorption spectra band intensities. In the case of irradiation, the absorption band intensity decreases higher than without irradiation. The binding constant of Pb(II) with Spirulina platensis is calculated for nutrition medium with pH 9.2. DSC data show that Cd(II) and Pb(II) ions do not change the integral heat of absorption (Δ H m ) that equals to 24.6 J g -1 . In the case of irradiation, the DSC melting curve profile changes significantly and Δ H m decreases two times, which indicates that 50 % of proteins are denaturated. The DSC method also gives a possibility to evaluate C-phycocyanin content from deconvoluted heat absorption peak at 50 °C, which equals to 35.5 %. In case of irradiated wet mass, sub-cultured wet mass, and wet mass re-irradiated with the same dose, contents of Spirulina platensis ingredients – C-phycocyanin, chlorophyll, and carotenoids – increase as a result of the simultaneous effect of the metal ions and irradiation.

Toxic Metals Removal from Industrial Sludge by Using Different Leaching Solutions

The safety of the environment from the industrial sludge has become a serious concern in India with the rapid increase in industrialization. The indiscriminate disposal of sludge from industries leads to the soil, groundwater and surface water pollutions. To avoid the high costs associated with the disposal of large volumes of sludge, it can be used in some building materials or can be used as fertilizer. As the accumulation of heavy metals in plants causes a threat to living beings, it has to be pretreated to remove heavy metals from the sludge to the required level before its application to soils. The heavy metals from the sludge can be reduced/separated by washing with a suitable fluid. In the present study, column leaching tests were conducted with five leaching solutions, i.e., distilled water, 0.1 N HCl, 0.1 N EDTA, 0.1 N HCl + 0.1 N EDTA and 0.1 N FeCl3 to know their removal efficiencies of heavy metal ions of Cu, Zn, Ni, Cd, Pb, Fe and Cr present in the industrial sludge. It was observed that distilled water was able to remove only few metal ions Cu, Zn and Ni in lesser quantities. 0.1 N HCl has removed Cd, Cu, Zn and Ni ions with a removal efficiency of 50%. With 0.1 N EDTA, the metal ions Cd, Cu and Zn have attained a removal efficiency of 80% and other metals have attained almost 50%. Using 0.1 N HCl + 0.1 N EDTA and 0.1 N FeCl3, all the heavy metals were leached out with removal efficiencies of (different metals) 71–98%. From this study, it was found that 0.1 N HCl + 0.1 N EDTA and 0.1 N FeCl3 were the most suitable solutions to remove heavy metals from the industrial sludge. Using the results of column leaching tests, the migration rates of different metal ions were determined which are used to design the soil washing program at the site to treat the similar sludge.

Identification and biochemical characterization of a novel exo-type β-agarase Aga3463 from an Antarctic Pseudoalteromonas sp. strain.

An agar-degrading Antarctic bacterium was isolated and identified as Pseudoalteromonas sp. NJ21. This strain showed strong agarolytic activity and could use agar as the sole carbon source for growth. A novel β-agarase gene aga3463 was cloned and identified from the genomic library of Pseudoalteromonas sp. NJ21. It was predicted to encode a peptide of 366 amino acids, including a 21-amino-acid signal peptide. BLAST analysis revealed the deduced amino acid sequence of aga3463 shared less than 36% similarity with any characterized agarase, and phylogenetic analysis showed it belonged to the glycoside hydrolase GH86 family. The recombinant Aga3463 protein had optimal temperature and pH of 50 °C and 7.0, respectively, and retained more than 60% activity from 10 to 50 °C. The metal ions Cd2+, Ca2+, Fe3+, and Mn2+ increased Aga3463 activity, whereas Cu2+, Si2+, Fe2+, and Ni2+ decreased Aga3463 activity. Notably, Aga3463 exhibited good thermostability in the presence of Ca2+; however, Ca2+ was not necessary for its catalytic activity. The Km and Vmax values for Aga3463 were 6.17 mg/ml and 557 U/mg, respectively. Thin layer chromatography, liquid chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy, and enzyme assay using p-nitrophenyl-α/β-d-galactopyranoside revealed Aga3463 as an exo-type β-agarase with the ability to degrade agarose to neoagarobiose as the major end product.

A nanocomposite consisting of porous graphitic carbon nitride nanosheets and oxidized multiwalled carbon nanotubes for simultaneous stripping voltammetric determination of cadmium(II), mercury(II), lead(II) and zinc(II).

A 3D nanocomposite consisting of porous graphitic carbon nitride nanosheets (p-g-C3N4-NSs) and oxidized multiwalled carbon nanotubes (O-MWCNTs) was prepared by simultaneous chemical oxidation of bulk g-C3N4 and bulk MWCNTs. This one-step oxidation results in the formation of acidic functional groups on the basal surfaces of both g-C3N4 and MWCNTs. Simultaneously, the O-MWCNTs are incorporated in-situ on the porous structure of p-g-C3N4. The acid functionalization and surface morphology of the nanocomposite were examined using attenuated total reflectance infrared spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy. The nanocomposite was used to modify a screen-printed electrode (SPE) which then was studied by using cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The modified SPE exhibits excellent sensitivity and selectivity towards the simultaneous detection of the heavy metal ions Cd(II), Hg(II), Pb(II) and Zn(II), typically at -0.78, +0.35, -0.5 and - 1.16V (vs. Ag/AgCl). The detection limits (at S/N = 3) range between 8 and 60ngL-1 under conditions of stripping analysis. The method was applied to the simultaneous detection of these ions in various (spiked) food samples. The results demonstrated the good accuracy and reproducibility of the method. Graphical abstract Schematic of a highly sensitive and selective electrochemical method for the simultaneous detection of four heavy metals. It is based on the use of a screen printed electrode (SPE) modified with3D porous g-C3N4 andO-MWCNTs, and of anodic stripping voltammetry.

Transcriptome analysis revealed pivotal transporters involved in the reduction of cadmium accumulation in pak choi (Brassica chinensis L.) by exogenous hydrogen-rich water

Hydrogen-rich water (HRW) has been widely used in research on plant resistance to Cd. However, the underlying molecular mechanism of HRW in ameliorating cadmium stress in vegetables is largely unknown. In this study, the RNA-sequencing analyses were used to characterize the role of HRW in the alleviation of Cd toxicity in Chinese cabbage seedlings. Based on the obtained results, two genes encoding metal ionic transporters, BcIRT1 and BcZIP2 were ultimately selected out. Then, a systematic validation of the metal ion transport function of these two ZIP-encoding genes of pak choi were performed via a yeast transformation system. The results showed that BcIRT1 and BcZIP2 increased the sensitivity of different yeast mutant strains to relative metal ionic stresses and facilitated the accumulation of metal ions (Cd2+, Mn2+, Zn2+, and Fe2+) in yeast; thus, it suggests that BcIRT1 and BcZIP2 probably have the ability to transport Cd2+, Mn2+, Zn2+ and Fe2+ in pak choi. The time-course and concentration-dependent expression profiles of BcIRT1 and BcZIP2 showed that as time with HRW increased, the effectiveness of the repression on the expression of BcIRT1 and BcZIP2 increased, and as the seedlings were exposed to increased Cd concentrations, the inhibition of BcIRT1 and BcZIP2 by HRW was also increased. Over all, these findings provide new insights into the genome-wide transcriptome profiles in pak choi and show that HRW reduced Cd uptake probably through inhibiting the expression of transporters related to Cd absorption, BcIRT1 and BcZIP2.

DFT study on the selective complexation of meso-2,3-dimercaptosuccinic acid with toxic metal ions (Cd2+, Hg2+ and Pb2+) for pharmaceutical and biological applications

In this work, density functional theory (DFT) calculations were performed to investigate the complex formation ability of Meso-2,3-dimercaptosuccinic acid (DMSA) with metal ions (Cd2+, Hg2+ and Pb2+) in water. The binding energy values and thermodynamic parameters have been calculated. Natural bond orbital and charge decomposition analyses show an effective charge transfer from the oxygen and sulfur atoms of the DMSA to metal ions. Quantum theory of atoms in molecules analysis reveals that the covalent interactions between DMSA and Pb2+ are the driving force in complex formation, while the non-covalent interactions, mainly, electrostatic interactions play an important role in the complex formation of the DMSA with Cd2+ and Hg2+. Finally, The electronic properties such as highest occupied molecular orbital, lowest unoccupied molecular orbital energies, electronic chemical hardness, electronic chemical potential and global electrophilicity were calculated to get a better insight of molecular properties.

Kinetics, thermodynamics and metal separation studies of transition (Co2+, Ni2+, Cu2+, Zn2+) and heavy metal ions (Cd2+, Hg2+, Pb2+) using novel hybrid ion exchanger—Zirconium amino tris methylene phosphonic acid

ABSTRACTZirconium amino tris(methylenephosphonic acid) (Zr-ATMP)—a novel hybrid ion-exchange material of the class of tetravalent metal acid (TMA) salts—has been synthesized via the sol–gel route using inexpensive and easily available chemicals. In the present endeavour, we hereby report various kinetic [ (D0), (Ea) (ΔS*) and thermodynamic parameters [ (K), (ΔG°), (ΔH°) (ΔS°) in the temperature range (30–60 °C)] for transition metal ions (Co2+, Ni2+, Cu2+, Zn2+) and heavy metal ions (Cd2+, Hg2+, Pb2+). Metal ion adsorption with varying concentrations and temperatures has been studied using Langmuir and Fruendlich adsorption isotherms. Sorption behaviour of the metal ions mentioned above towards Zr-ATMP has been studied by evaluating Kd (distribution coefficient) under different conditions. Based on Kd (mL.g−1), the selectivity order for metal ions towards Zr-ATMP is found to be Cu2+ (C.S)>Ni2+ (2980)>Zn2+(1810)>Co2+(1250) amongst transition metal ions and Pb2+(3612)>Cd2+(1601)>Hg2+(125) amongst heavy metal ions. Elution behaviour of these metal ions has been studied using acids and electrolytes. Based on α separation factor, a few binary and ternary metal ion separations have been carried out successfully. Regeneration and reuse of the ion exchanger have also been studied. It is observed that the ion exchanger is effective up to four cycles without much decline in performance. The study indicates that Zr-ATMP has good potential to be used as a cation exchanger.