Single Metal Ion Solutions Research Articles

Transporter drives the biosorption of heavy metals by Stenotrophomonas rhizophila JC1.

To better understand the function of transporter in heavy metal detoxification of bacteria, the transporters associated with heavy metal detoxification in S. rhizophila JC1 were analyzed, among which four members were verified by RT-qPCR. In addition, the removal rates of four single metal ions (Cr6+, Cu2+, Zn2+, Pb2+) and polymetallic ions by strain JC1 were studied, respectively. We also researched the physiological response of strain JC1 to different metal stress via morphological observation, elemental composition, functional group and membrane permeability analysis. The results showed that in the single metal ion solution, removal capacities of Cu2+ (120 mg/L) and Cr6+ (80 mg/L) of S. rhizophila JC1 reached to 79.9% and 89.3%, respectively, while in polymetallic ions solution, the removal capacity of each metal ion all decreased, and in detail, the adsorption capacity was determined Cr6+>Cu2+>Zn2+>Pb2+ under the same condition. The physiological response analyses results showed that extracellular adsorption phenomena occurred, and the change of membrane permeability hindered the uptake of metal ions by bacteria. The analysis of transporters in strain JC1 genome illustrated that a total of 323 transporters were predicted. Among them, two, six and five proteins of the cation diffusion facilitator, resistance-nodulation-division efflux and P-type ATPase families were, respectively, predicted. The expression of corresponding genes showed that the synergistic action of correlative transporters played important roles in the process of adsorption. The comparative genomics analysis revealed that S. rhizophila JC1 has long-distance evolutionary relationships with other strains, but the efflux system of S. rhizophila JC1 contained the same types of metal transporters as other metal-resistant bacteria.

Competitive adsorption of nickel(II) and cadmium(II) ions by chitosan cross-linked with sodium tripolyphosphate

This study investigates the adsorption of Ni(II) and Cd(II) ions from single and binary metal ion solutions onto chitosan and crosslinked chitosan beads, which was accomplished by an environmentally-friendly crosslinker, sodium tripolyphosphate. The synthesized adsorbents were characterized by swelling test, BET and SEM, and tested for Ni(II) and Cd(II) uptake after optimizing experimental factors, including adsorbent concentration (0.55 g/L) and initial pH (6.5). The single-ion equilibrium adsorption data fitted well by the Langmuir model. In the binary system, a decrease in adsorption capacity was observed, implying the existence of preference in the order of Ni(II) > Cd(II). Among the studied models for competitive adsorption, the extended Freundlich model fitted successfully for the adsorption equilibrium data. Characterization of loaded crosslinked chitosan beads showed amino and phosphate groups were responsible simultaneously for the metal ions uptake. Desorption experiments were also conducted by using a mixture of NaCl and H2SO4, showing acceptable results.

Selective separation of Cu(II) from a single metal ion solution by using O-amino thiophenol-modified flax fiber

A newly synthesized ortho-amino thio-phenol modified flax fibers (OATP-MFF) were prepared in two subsequent steps; at first flax fiber was pretreated with sodium periodate. Then the pretreated fibers were condensed with ortho-amino thio-phenol to form the modified flax fiber(OATP-MFF). The OATP-MFF was characterized by (FTIR) Fourier transform infrared spectra, SEM and energy-dispersive X-ray Spectroscopy (EDX). The newly synthesized OATP-MFF chelating fibers were utilized for selective separation of Cu(II) from aqueous solution by adsorption methodology. The effects of pH, the initial concentration of metal ions, the adsorbent dosage, the interfering ions and the contact time on the adsorption capacity of OATP-MFF chelating fibers were investigated. The maximum adsorption capacity of Cu(II) at the optimum conditions was 92 mg/g. The adsorption process fitted well the second-order model kinetic of. The chemical (adsorption) reaction is the rate-limiting step that was proved from the kinetic model.

Competitive and non-competitive zinc, copper and lead biosorption from aqueous solutions onto flax fibers

Competitive and non-competitive batch experiments were conducted on flax fibers to study Zn2+, Cu2+, and Pb2+ ions biosorption performance. Biosorption efficiency was dependent on contact time, pH, and biosorbent concentration. The results under competitive conditions were different from those obtained in non-competitive form. A high affinity of lead, with a selectivity sequence in general of Pb > Cu > Zn was observed. The biosorption data fitted very well the Langmuir model for lead in both types of solutions and for zinc and copper in the monometal form. The fit with the Freundlich model was not as successful, except for copper in the ternary system. Regarding zinc under competitive conditions, the sorption process was quite difficult and thus the equilibrium data could not fit well the adsorption models. The maximum adsorption capacities (mmol.kg−1) were respectively 112, 122 and 71, for Pb, Cu and Zn in the single metal ion solution and 82, 57 and 8 only in the ternary, showing thus a high competition between metal ions when added simultaneously. Overall, lead could still be efficiently removed in spite of the presence of other ions while zinc would be overcome in the presence of lead and copper.

Spherical Chitosan/Gelatin Hydrogel Particles for Removal of Multiple Heavy Metal Ions from Wastewater

This article describes a simple preparation of chitosan/gelatin (CG) spherical hydrogel particles for the effective removal of multiple heavy metal ions. The CG hydrogel particles were prepared by inverse emulsion from the aqueous solutions of chitosan, gelatin, and glutaraldehyde. The oven-dried C2G1 hydrogel particles showed a maximum removal efficiency of 98% for Hg(II) ions in a single metal ion solution and which was higher than C1G1 (85%) and C1G2 (58%) particles. This result was affected by the composition of the hydrogels rather than the pore size or degree of swelling. Remarkably, the removal efficiencies for the Pb(II), Cd(II), Hg(II), and Cr(III) ions reached about 73%–94% in a multiple metal ion solution. The results indicate that the CG hydrogel particles can be used to remove coexisting heavy metal ions from wastewater, providing a versatile method to remove multiple metal ions from natural or industrial wastes.

Kinetic Studies of Zn(II) Removal from Single and Binary Solutions by Synthetic Hydroxyapatite - Based Nanopowders

A kinetic study has been carried out with two hydroxyapatite nanopowders to establish the mechanism involved in heavy metals removal from aqueous synthetic solutions. The samples of nanohydroxyapatite have been previously characterized. The first sample represents a pure hydroxyapatite (HAP) nanopowder named HAP-1, and the second sample (HAP-2) consist of a mixture of hydroxyapatite (HAP; Ca10(PO4)6(OH)2) and b-tricalcium phosphate (b-TCP; Ca3(PO4)2). Batch experiments with single and binary Zn(II) and Pb(II) aqueous solutions have been performed. According to this research study, it was found that the both nanohydroxyapatite samples show good heavy metals adsorption capacity, and selectivity for Pb(II) ions. A more pronounced decreasing of sorption capacity of Zn(II) ions from binary solutions compared to that registered from single heavy metal ion solutions has been observed. From the kinetic point of view, the sorption process can be described for both heavy metals as a pseudo-second-order kinetic process. According to this model, the Zn(II) and Pb(II) sorption can be achieved by chemical reactions between heavy metals and functional groups of adsorbents. The obtained results are indicative of good hydroxyapatite adsorption ability towards Pb(II) and Zn(II) ions.

The Influence of Synthesis Conditions on Hydroxyapatite Adsorption Characteristics in the Process of Zn(II) and Pb(II) Removal from Single and Binary Solutions

Two types of nanohydroxyapatite samples have been obtained by wet chemical precipitation synthesis, involving calcium nitrate tetrahydrate and diammonium hydrogen phosphate as precursors in different conditions. Powders obtained were characterized by X-ray diffraction (XRD) and FTIR spectroscopy. The equilibrium isotherm models related with lead and zinc ions removal from synthetic aqueous solutions have been also investigated. According to this research study, it has been found that the nanohydroxyapatite samples show good heavy metals adsorption capacity, and selectivity for lead ions. It was also observed a slow decreasing of sorption capacity of heavy metal ions from binary solutions compared to that registered from single heavy metal ion solutions.

Equilibrium, kinetic and mechanism studies of Cu(II) and Cd(II) ions adsorption by modified chitosan beads

In this study, the Cu(II) and Cd(II) ions removal behavior of crosslinked chitosan beads grafted poly(methacrylamide) (abbreviated as crosslinked chitosan-g-PMAm) from single metal ion solutions was investigated. The modified chitosan beads presented a remarkable improvement in acid resistance. The batch experiments demonstrated that pH of solution played a significant role in adsorption. It was found that the adsorption of Cu(II) and Cd(II) were optimum at pH 4 and pH 5, respectively. The maximum adsorption capacities for Cu(II) and Cd(II) based on Langmuir equation were 140.9 mg g−1 and 178.6 mg g−1, respectively. Pseudo-second order gave a better fit for adsorption data with respect to linearity coefficients than pseudo-first order suggesting that chemisorption or electron transfer is the dominant mechanism of the metal ions onto crosslinked chitosan-g-PMAm. In addition, X-ray photoelectron spectroscopy (XPS) investigations revealed that adsorption of both metal ions took place on the surfaces of crosslinked chitosan-g-PMAm by chelation through CNH2, CO and CO groups. Overall, the modified chitosan has proved a promising adsorbent for removal of metal ions.

Lead and cadmium removal from single and binary metal ion solution by novel hydroxyapatite/alginate/gelatin nanocomposites

Imperfect treatment of effluents from the industries contain moderate amounts of metallic cations will carry other issues to human health and environment. When toxic substances enter into water bodies, they get dissolved in water or get deposited on the bed. This results in the deterioration of water thereby affecting the aquatic ecosystems. In the area of environmental remediation, nanosized materials offer potential for efficient removal of pollutants and biological contaminants. In this present work, heavy metal ions (Pb2+ and Cd2+) sorption capacity of HA-alginate/gelatin nanocomposite has been investigated as a function of adsorbent dosage, adsorbate concentrations and contact time. The sorption kinetics exhibited the best fit to the pseudo-second order equation and the equilibrium followed Langmuir isotherm model. The equilibrium removal capacity of HA/Alg composite from Langmuir isotherm model was evaluated to be 550 and 361 mg/g for Pb2+ and Cd2+. The removal capacity of HA/Alg/Gel composite was evaluated to be 616 and 388 mg/g for Pb2+ and Cd2+. In the case of binary metal ion system, removal capacity of the adsorbent for a particular metal ion was hindered by the presence of another ion in the medium. The results of this study will be useful for further development of ceramic/polymer composites for environmental applications.

Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide.

Phytate intercalated MgAl layered double hydroxide (MgAl-LDH) was prepared by an anion exchange method with the precursor NO3- containing MgAl-LDH. The final as-synthesized product [Mg0.69Al0.31(OH)2] (phytateNa6)0.05 (NO3)0.01·mH2O (phytate-LDH) has highly selective adsorption ability for some metal ions and can be used to enrich rare earth metal ions in mixed solution, such as Pr3+ and Ce3+ from a mixed solution of them with Pb2+ and Co2+. At first, phytate-LDH has good adsorption performance for these ions in single metal ion solutions. At low concentration (below 10 mg L-1), all the capture rates of the four metal ions were more than 97%, for highly toxic Pb2+ it was even up to nearly 100%, and a high capture rate (99.87%) was maintained for Pb2+ at a high concentration (100 mg L-1). When all the four metal ions are co-existing in aqueous solution, the selectivity order is Pb2+ ≫ Pr3+ ≈ Ce3+ > Co2+. In a solution containing mixtures of the three metal ions of Pr3+, Ce3+, and Co2+, the selectivity order is Pr3+ ≈ Ce3+ ≫ Co2+, and in a solution containing mixtures of Pr3+ with Co2+ and Ce3+ with Co2+, the selectivity orders are Pr3+ ≫ Co2+ and Ce3+ ≫ Co2+, respectively. The high selectivity and adsorption capacities for Pb2+, Co2+, Pr3+, and Ce3+ result in the efficient removal of Pb2+ and enrichment of the rare earth metal ions Pr3+ and Ce3+ by phytate-LDH. Based on the elemental analysis, it is found that the difference of the adsorption capacities is mainly due to the different coordination number of them with phytate-LDH. With molecular simulation, we believe that the adsorption selectivity is due to the difference of the binding energy between the metal ion and phytate-LDH. Therefore, the phytate-LDH is promising for the enrichment and/or purification of the rare earth metal ions and removal of toxic metal ions from waste water.

Antimicrobial Efficacy and Synergy of Metal Ions against Enterococcus faecium, Klebsiella pneumoniae and Acinetobacter baumannii in Planktonic and Biofilm Phenotypes

The effects of metal ion solutions (silver, copper, platinum, gold and palladium) were determined individually and in combination against Enterococcus faecium, Acinetobacter baumannii and Klebsiella pneumoniae. Platinum, gold and palladium showed the greatest antimicrobial efficacy in zone of inhibition (ZoI) assays. When tested in combinations using ZoI assays, gold/platinum, gold/palladium and platinum/palladium were indicative of synergy. Microbial inhibitory concentration demonstrated platinum and gold against Enterococcus faecium, platinum against Klebsiella pneumoniae and platinum and silver against Acinetobacter baumannii were optimal. Minimal bactericidal concentrations determined the greatest bactericidal activity was again platinum gold and palladium against all three bacteria. Fractional Inhibitory Concentration (FIC) studies demonstrated that the silver/platinum combination against Enterococcus faecium, and silver/copper combination against Acinetobacter baumannii demonstrated antimicrobial synergy. Following crystal violet biofilm assays for single metal ion solutions, antimicrobial efficacies were demonstrated for all the metals against all the bacteria Synergistic assays against biofilms demonstrated gold/palladium, gold/platinumand platinum/palladium resulted in the greatest antimicrobial efficacy. Overall, platinum, palladium and gold metal ion solutions in individual use or combination demonstrated the greatest antimicrobial efficacies against planktonic or biofilm bacteria. This work demonstrates the potential for using a range of metal ions, as biocidal formulations against both planktonic or biofilm bacteria.

Effect of Ionic Strength on the Adsorption of Pb 2+ and Cu 2+ onto Bentonite/Sodium Lignosulfonate Graft-Polymerized with Acrylamide and Maleic Anhydride

Adsorbent composites comprising of bentonite / sodium lignosulfonate graft-polymerized with acrylamide and maleic anhydride( BLPAMA) were prepared and used to investigate the effect of ionic strength on the adsorption of Pb2 +or Cu2 +onto BLPAMA in single or binary metal ion solutions,the adsorption isotherms,kinetics and thermodynamics of Pb2 +and Cu2 +onto BLPAMA with or without addition of0. 2 mol / L Na NO3 in the binary metal ion solutions. The results show that the increase of ionic strength leads the adsorption capacity of Pb2 +or Cu2 +to decrease in the single metal ion solution,the adsorption capacity of Pb2 +to decrease while the adsorption capacity of Cu2 +to increase in the binary metal ion solution.

Adsorption of Cr(III) ions using 2-(ureylenemethyl)pyridine functionalized MCM-41

Modified MCM-41 material with uniform meropore channels was prepared by surfactant-directed synthesis strategy and post functionalized with 3-(triethoxysilyl)propyl isocyanate (ICPES). By utilizing the reaction between –NCO group of ICPES and –NH2 group of 2-picolylamine in acetonitrile, the chelating ligand, 2-(ureylenemethyl)pyridine, has been successfully immobilized over MCM-41 (UMP-MCM-41) without destroying the mesoporous structure. The synthesized materials show very good mesoporosity and long range order. The ability of removing chromium from water and artificial seawater by using the UMP-MCM-41 mesoporous material was explored. The synthesized material showed good adsorption ability for Cr(III) ions from water and artificial seawater with selectivity of 36 and 64 %, respectively, in the presence of interfering metal ions such as Zn(II), Cd(II), Co(II), and Cu(II). In order to disclose the adsorption ability of the material from single metal ion solution for Cr(III) ion, factors such as effect of pH, stirring time, initial ion concentration and presence of ethanol in adsorption medium were also explored. Further the experiments revealed that the UMP-MCM-41 is giving maximum adsorption at pH 6. The adsorption equilibrium has been attained within 5 h with 84 % adsorption. Moreover, the presence of ethanol in the adsorption medium enhances the amount of adsorption.

Applications of chelating resin for heavy metal removal from wastewater

AbstractThe chelating resin was synthesized by free-radical copolymerization of iminodiacetic acid modified glycidyl methacrylate with a cross-linker N,N′-methylene biscarylamide at 70°C for removal of heavy metal ions from aqueous solutions. The equilibrium adsorption capacities of the chelating resin from their single-metal ion solutions were 3.28 mmol/g for Cd(II), 2.36 mmol/g for Cu(II), 1.71 mmol/g for Mn(II), 1.69 mmol/g for Ni(II), 1.41 mmol/g for Zn(II), 1.24 mmol/g for Co(II), 0.78 mmol/g for Cr(III) and 0.66 mmol/g for Pb(II). Their related absorption behaviors are discussed in this paper such as thermodynamic equilibrium, pH effect and the Langmuir and Freundlich model to evaluate the experimental data. According to the results, this resin could be used as a promising adsorbent for industrial wastewater disposal.

Water-soluble oxidized starch in complexation of Fe(III), Cu(II), Ni(II) and Zn(II) ions

The structure of the bromate-oxidized wheat starch (OS) contains partly opened glucose units with carbonyl and carboxyl groups at C2-, C3- or C6-positions. OS with a variable degree of oxidation (DO) was studied in alkaline conditions as a water-soluble complexing agent for Fe(III), Cu(II), Ni(II) and Zn(II) ions, which are common in various wastewaters. Complexation was studied by inductively coupled plasma-optical emission spectrometry (ICP–OES) in a single metal ion or multi-metal ion solutions. The DO affected the efficiency of the complexation with metal ions. OS with the high DO (carboxyl and carbonyl DO of 0.72 and 0.23, respectively) complexed and held Fe(III) or Zn(II) ions in a soluble form effectively in 0.5mM single ion alkaline solution with the molar ratio of 0.65:1 of oxidized starch-to-metal ion (OS-to-M). The OS-to-M molar ratio of 1.3:1 was required to form a soluble complex with Cu(II) or Ni(II) ions. These complexes were thermally stable at the temperature range of 20–60°C. OS with the low DO (carboxyl and carbonyl DO 0.47 and 0.17, respectively) complexed Zn(II) ions highly, Cu(II) and Ni(II) ions poorly and Fe(III) ions only partly. In the multi-metal ion solution of OS the solubility of these metal ions improved with the increasing DO of starch, which followed the same tendency as was observed in the single metal ion systems. The increased molar ratio of OS-to-M improved the complexation and solubility of the metal ions in all multi-metal ion series. As the soluble multi-metal ion complexes were reanalyzed after 7days, all solutions had kept the high complexation and solubility of metal ions (ca. 90%). Complexation by OS did not show a selective binding of the ions in the multi-metal ion solution. It was concluded that the flexible, opened ring structure units of OS prevented the selective binding to metal ions but made the complexes highly stable. Titrimetric studies of OS–Fe(III) complexation showed that each anhydroglucose unit of OS had more than one coordination site and as the content of OS increased, the free sites coordinated to Fe(III) ions and formed cross-linked starch structures.

Recycled chitosan nanofibril as an effective Cu(II), Pb(II) and Cd(II) ionic chelating agent: Adsorption and desorption performance

Mechanically disassembled chitosan nanofibrils were prepared and used as metal ion chelating agents. Structure and morphology of nanofibrils were investigated and ionic adsorption or desorption performance were validated to establish related fitting models. In single metal ion solution, the saturated adsorption capacities of Cu(II), Pb(II), Cd(II), Zn(II), and Ni(II) were 168.66, 118.00 and 60.85, 143.67, and 63.32mg/g, respectively. In ternary metal ion solution, Cu(II) was more competitive to be adsorbed than Pb(II) and Cd(II) and its removal could arrive at 60%. Ions adsorbed by nanofibrils could be released by EDTA and the recovery could keep above 70% after 3 sorption–desorption cycles. Hence, renewable and recyclable nanofibrillar chitosan exhibited a great promising application in metal treatments attributed to its high adsorption capacity and chelation efficiency.

Removal of heavy metal ions from aqueous solution by chemically modified mangosteen pericarp

AbstractAn efficient biosorbent was prepared from mangosteen pericarp by saponification with alkaline solution of calcium hydroxide and sodium hydroxide. Batch wise adsorption tests were conducted to investigate the effect of pH, adsorption isotherm, and adsorption kinetics for heavy metal ions. It was found to exhibit fairly good adsorption behavior for heavy metal ions like lead, cadmium, iron, copper, nickel, and zinc ions, with the selectivity order for metal ion adsorption as Fe(III) > Pb(II) > Cu(II) > Cd(II) > Zn(II) > Ni(II). Their adsorption process can be described well by Langmuir model and pseudo-second-order kinetics equation. Among these metal ions, maximum adsorption capacity was evaluated to be 1.48, 1.20, 0.47, 0.35 mol/kg for Cu(II), Fe(III), Ni(II), Cd(II) at equilibrium pH 5.0 (except for Fe(III) at pH 2.8), respectively, while 1.01 mol/kg for both Pb(II) and Zn(II) in the single metal ion solution. The adsorption capability of the modified mangosteen pericarp for heavy metal ions can ...

Liquid-Liquid Extraction of Platinum from Chloride Media by N,N′-Dimethyl-N,N′-Dicyclohexyltetradecylmalonamide

Liquid-liquid extraction of platinum(IV) from chloride media was carried out using N,N′-dimethyl-N,N′-dicyclohexyltetradecylmalonamide (DMDCHTDMA) in 1,2-dichloroethane. Platinum can be effectively extracted by DMDCHTDMA without addition of tin(II) chloride, since extraction percentages (%E) of 88% and 99% have been achieved from 6 M and 8 M HCl, respectively. Moreover, platinum can be successfully stripped through a simple contact with a 1 M HCl solution. The effect of some experimental parameters such as equilibration time, diluent, extractant and HCl concentrations was systematically investigated. The loading capacity of DMDCHTDMA was also evaluated. Data obtained from successive extraction-stripping cycles suggest a good stability pattern of DMDCHTDMA. Preliminary extraction data achieved with single metal ion solutions pointed out to a possible separation of platinum(IV) from palladium(II).

Uptake of hazardous heavy metal ions by aqueous solution of poly(acrylamide) prepared through atom transfer radical polymerization process

AbstractPoly(acrylamide) (PACM) used in this study was prepared through an effective atom transfer radical polymerization process and characterized by NMR, FTIR, and thermo gravimetric analysis. Resulting polymer was used for the uptake of heavy metal ions from aqueous solution. Partition coefficient, retention capacity, and metal ion uptake behavior in aqueous solution of PACM at different monomer percent conversions and effect of parameters for optimization of polymerization reaction gives thermally stable PACM. Efficiency of metal ion uptake of different molecular weights of PACM were tested in batches for Ni2+, Pb2+, Cu2+, Zn2+, and Hg2+ ions in single metal solution. Metal ion sorption capacities increase with increase in polymer concentration. Metal ion sorption capacities in single metal system were 6.3 mg g−1 Ni2+, 6.0 mg g−1 Pb2+, 6.9 mg g−1 Cu2+, 6.2 mg g−1 Zn2+, 22.4 mg g−1 Hg2+ for PACM of 88% conversion (Mn = 19,850). Uptake by the PACM indicates that they are effective in removing metal ions from single metal ion solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Polymer enhanced membrane filtration of metals: retention of single and mixed species of metal ions based on adsorption isotherms

The binding and retention of single metal ions and mixtures of metal ions with polyethylenimine (PEI) was studied using polymer enhanced ultrafiltration (PEUF). Using a highly branched chain form of PEI (Sigma Aldrich 181979) with an average molecular weight 750,000 and approximately 60,000, ultrafiltration experiments were carried out in the stirred dead-end ultrafiltration mode. The results of the binding studies show that the Langmuir isotherm offers a good description of the binding process. At pH 5.5, the maximum polymer binding (Q max) and binding affinity constant (K L) were determined according to Langmuir isotherms. It was observed that the maximum amount of metal ions bound to the polymer for Cu2+, Zn2+, Ni2+ and Cd2+ decreased substantially in solutions containing mixtures of metal ions when compared to the values obtained for single metal ion solutions. For Cr6+ and Co2+ no significant decrease was seen. These data indicate that the binding capacity of Cr6+ and Co2+ remain constant in competit...