Separation Of Heavy Metal Ions Research Articles

Influence of N-phthaloyl chitosan on poly (ether imide) ultrafiltration membranes and its application in biomolecules and toxic heavy metal ion separation and their antifouling properties

N-phthaloyl chitosan (NPHCs), which could be dissolved in various organic solvents, is synthesized for the modification of poly (ether imide) (PEI) ultrafiltration membrane. Blend membrane with 2wt% NPHCs exhibited higher pure water flux (112.2lm−2h−1), higher water content (63.4%) and lower hydraulic resistance (3kPa/lm−2h−1). The top surface morphology of the control PEI membrane changed from a dense surface to visible pores with the increase in NPHCs concentration. The surface roughness of PEI membranes increased with an increase in NPHCs concentration in the casting solution. Application studies were carried out to find the rejection and permeate flux of proteins such as bovine serum albumin (BSA), egg albumin (EA), pepsin and trypsin and toxic heavy metal ions such as Cr(III), Zn(II), Cd(II) and Pb(II). The result shows that the flux and separation performances are dependent upon the content of NPHCs. Furthermore, the blend membranes were subjected to the determination of pore statistics and MWCO. It was found that the blending of NPHCs into the PEI membrane had a visible effect upon MWCO and pore size. The significant effect of hydrophilicity of NPHCs on the fouling of PEI/NPHCs blend membranes by BSA was also discussed. It was found that the blend membranes with 2wt% NPHCs content had a higher FRR (88.6%), higher reversible fouling (23.7%) and lower irreversible fouling (11.4%) which explained their improved antifouling properties. Thus, the modified chitosan proved to play an important role in the improvement of UF membrane performance.

Europium(III) complex-functionalized magnetic nanoparticle as a chemosensor for ultrasensitive detection and removal of copper(II) from aqueous solution.

Ultrasensitive, accurate detection and separation of heavy metal ions is very important in environmental monitoring and biological detection. In this paper, a highly sensitive and specific detection method for Cu(2+) based on the fluorescence quenching of a europium(III) hybrid magnetic nanoprobe is presented. This nanoprobe can detect Cu(2+) over a wide pH range (5.0-10.0) with a detection limit as low as 0.1 nM and it can be used for detecting Cu(2+) in living cells. After the magnetic separation, the Cu(2+) concentration decreased to 1.18 ppm, which is less than the US EPA drinking water standard (1.3 ppm), and more than 70% Cu(2+) could be removed when the amount of nanocomposite 1 reached 1 mg.

Separation of Trace Heavy Metal Ions from Leaching Liquor of Low-Grade Pyrolusite with Pyrite and H<sub>2</sub>SO<sub>4</sub>

Separation of trace heavy metal ions with BaS from solutions of five kinds of systems was studied. One was prepared with the solution (called as original solution here) leached from pyrolusite with pyrite and H2SO4, and the other four kinds of systems were prepared in the laboratory according to the composition of the original solution. They are respectively: a ternary system of NiSO4CoSO4ZnSO4; two quaternary systems of (NH4)2SO4NiSO4CoSO4ZnSO4 and MnSO4NiSO4CoSO4ZnSO4; a quintuple system of MnSO4(NH4)2SO4NiSO4CoSO4ZnSO4. The experiments have researched the effect of reaction time and dosage of BaS on the separation of heavy metal ions. According to the results, it took the five systems 10minutes to reach the equilibrium state and re-dissolution was found in the results. As the increasing of BaS dosage, the residual heavy metal ions would reduce, but the results of five systems were different when the same BaS was used.

Synthesis, characterization, thermal behaviour and transport properties of polyvinyl chloride based zirconium phosphate composite membrane

The polyvinyl chloride (PVC) based zirconium phosphate composite membrane was synthesized by co-precipitation method. The composite membrane was characterized by using Fourier transform infrared (FTIR) spectroscopy, thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). The order of charge effectiveness was found to be HgCl2<PbCl2<CdCl2. This composite membrane showed potential applications in the area of separation of heavy metal ions from wastewater because of good stabilities, long lifetimes and cost effectiveness.

Metakaolin-Based Geopolymers for Targeted Adsorbents to Heavy Metal Ion Separation

Geopolymer adsorbents were prepared from silica and metakaolin in different Al and Si components and applied for removal of metal ions, Cs+ and Pb2+, from other heavy metal ions mixture. The geopolymer was optimized at Si/Al = 2 as adsorbent, targeting to Cs+ and Pb2+ separation. The binding behavior was well fitted to Langmuir model, which proved that the metakaolin-based geopolymer had multibinding to adsorb ions. The effective adsorption was also observed independent of NaCl concentration for the Cs+ and Pb2+. This meant that the ion adsorption of geopolymers occurred under non-electrostatic mechanism.

Polyamidoamine dendrimers as sweeping agent and stationary phase for rapid and sensitive open-tubular capillary electrophoretic determination of heavy metal ions

Polyamidoamine (PAMAM) dendrimer generation 2.5 was synthesized and evaluated as sweeping agent for in-column enrichment and as stationary phase for capillary electrochromatographic separation of heavy metal ions, viz., Pb(II), Cu(II), Hg(II), Zn(II) and Co(II), in a running buffer containing 4-(2-pyridylazo)resorcinol (PAR) as a chromogenic reagent. During experiment, a plug of aqueous PAMAM generation 2.5 solution was first introduced to the capillary, followed by electrokinetic injection of the heavy metal ions under a positive voltage. In this step, PAMAM acted as a sweeping agent, stacking the metal ions on the analyte/PAMAM boundary by forming metal ion-PAMAM complexes. The second preconcentration process occurred when PAR, a stronger ligand, moving toward the injection end under the electric field, reached and re-swept the metal ion-PAMAM zone, forming metal ion-PAR complexes. During separation, the neutral PAMAM moved toward the detector with the electroosmotic flow, dynamically coating the capillary wall, forming stationary phases that affected the separation of the metal ions. Due to the function of PAMAM, the detection sensitivity and resolution of the heavy metal ions improved significantly. Under the optimum conditions, the detection limits were 0.299, 0.184, 0.774, 0.182 and 0.047 μg/L for Pb(II), Cu(II), Hg(II), Zn(II) and Co(II), respectively. The method was successfully applied to the determination of heavy metals in snow, tap and rain water samples.

Magnetic separation of heavy metal ions and evaluation based on surface-enhanced Raman spectroscopy: Copper(II) ions as a case study

A new approach was developed for the magnetic separation of copper(II) ions with easy operation and high efficiency. p-Mercaptobenzoic acid served as the modified tag of Fe2O3@Au nanoparticles both for the chelation ligand and Raman reporter. Through the chelation between the copper(II) ions and carboxyl groups on the gold shell, the Fe2O3@Au nanoparticles aggregated to form networks that were enriched and separated from the solution by a magnet. A significant decrease in the concentration of copper(II) ions in the supernatant solution was observed. An extremely sensitive method based on surface-enhanced Raman spectroscopy was employed to detect free copper(II) ions that remained after the magnetic separation, and thus to evaluate the separation efficiency. The results indicated the intensities of the surface-enhanced Raman spectroscopy bands from p-mercaptobenzoic acid were dependent on the concentration of copper(II) ions, and the concentration was decreased by several orders of magnitude after the magnetic separation. The present protocol effectively decreased the total amount of heavy metal ions in the solution. This approach opens a potential application in the magnetic separation and highly sensitive detection of heavy metal ions.

Separation of Heavy Metal Ions from the Solution Obtained by Leaching Low-Grade Pyrolusite with Pyrite and H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;

The manganese sulfate solution leached from low-grade pyrolusite with pyrite and H2SO4 contains heavy metal ions of high concentration, influencing the quality of the final products of manganese compounds and causing manganese ions not to be electrolyzed. The present study was focused on the separation of Co, Ni and Zn ions from the leached solution with BaS. By controlling the pH value at 5.0-6.5, temperature at 50-60°C, reaction time at 15 min and mixing velocity at 78 rpm, the heavy metal ions could be separated effectively. Under the above optimized conditions, the ion concentration of Co, Ni, and Zn in the solution was reduced to 0.06 mg.L-1, 0.27mg.L-1 and 0.01mg.L-1, and the separation efficiency was 99.72%, 99.18% and 99.9% respectively. The obtained pure solution meets the demands of manganese electrowinning.

Functionalization of polymer surfaces by radiation-induced grafting for separation of heavy metal ions

The reported investigations were focused on the elucidation of the most important factors influencing radiation-induced grafting, particularly on studying the relationship between layer structure formed via copolymerization and content of monomers in the initial solution. Sorption capacity of the prepared by radiation grafting adsorber was evaluated by gamma radiometer using 152Eu3+ as a marker monitoring depletion of the radioisotope from the feed solution.When two monomers, AAc and AAm, contributed in the formation of grafted layer, their input into copolymerization was not proportional to their concentrations in the feed solution. It was confirmed that grafting of the monomers shows synergetic effect as the yield of copolymerization exceeds degree of grafting achieved for the individual components.

Magnetic Separation Dynamics of Colloidal Magnetic Nanoparticles

Surface functionalized magnetic nanoparticles (MNPs) are appealing candidates for analytical separation of heavy metal ions from waste water and separation of actinides from spent nuclear fuel. This work studies the separation dynamics and investigates the appropriate magnetic-field gradients. A dynamic study of colloidal MNPs was performed for steady-state flow. Measurements were conducted to record the separation time of particles as a function of magnetic field gradient. The drag and magnetic forces play a significant role on the separation time. A drop in saturation magnetization and variation of particle size occurs after surface functionalization of the MNPs; these are the primary factors that affect the separation time and velocity of the MNPs. The experimental results are correlated to a theoretical one-dimensional model.

Determination of cadmium(II), cobalt(II), nickel(II), lead(II), zinc(II), and copper(II) in water samples using dual-cloud point extraction and inductively coupled plasma emission spectrometry

A dual-cloud point extraction (d-CPE) procedure has been developed for simultaneous pre-concentration and separation of heavy metal ions (Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion) in water samples by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure is based on forming complexes of metal ion with 8-hydroxyquinoline (8-HQ) into the as-formed Triton X-114 surfactant rich phase. Instead of direct injection or analysis, the surfactant rich phase containing the complexes was treated by nitric acid, and the detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by ICP-OES. Under the optimum conditions (pH=7.0, Triton X-114=0.05% (w/v), 8-HQ=2.0×10−4molL−1, HNO3=0.8molL−1), the detection limits for Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ions were 0.01, 0.04, 0.01, 0.34, 0.05, and 0.04μgL−1, respectively. Relative standard deviation (RSD) values for 10 replicates at 100μgL−1 were lower than 6.0%. The proposed method could be successfully applied to the determination of Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Cu2+ ion in water samples.

TiO2/bone composite materials for the separation of heavy metal impurities from waste water solutions

Pure bone material obtained from cow meat, as apatite-rich material, and TiO2-bone composite materials are prepared and studied to be used for heavy metal ions separation from waste water solutions. Meat wastes are chemically and thermally treated to control their microstructure in order to prepare the composite materials that fulfill all the requirements to be used as selective membranes with high performance, stability and mechanical strength. The prepared materials are analyzed using Hg-porosimetry for surface characterization, energy dispersive X-ray spectroscopy (EDAX) for elemental analysis and Fourier transform infrared spectroscopy (FTIR) for chemical composition investigation. Structural studies are performed using X-ray diffraction (XRD). Microstructural properties are studied using scanning electron microscopy (SEM) and specific surface area studies are performed using Brunauer-Emmet-Teller (BET) method. XRD studies show that multiphase structures are obtained as a result of 1h sintering at 700–1200 °C for both pure bone and TiO2-bone composite materials. The factors affecting the transport of different heavy metal ions through the selected membranes are determined from permeation flux measurements. It is found that membrane pore size, membrane surface roughness and membrane surface charge are the key parameters that control the transport or rejection of heavy metal ions through the selected membranes.

Synthesis and characterization of a new guar gum 4‐hydroxybenzoic acid resin and its use for the separation of heavy metal ions in industrial effluents

AbstractHydroxybenzoic acid group has been incorporated onto guar gum by modified Porath's method of functionalization of polysaccharides. The newly synthesized guar gum 4‐hydroxybenzoic acid (GHBA) resin was characterized by Fourier‐transform infrared spectroscopy, elemental analysis, ion‐exchange capacity, column reusability, and physicochemical properties. The distribution coefficient (Kd) values and effect of pH on chelation of these metal ions using batch method were studied. The separations of mixture of Fe2+, Zn2+, Cu2+, Cd2+, and Pb2+ metal ions on GHBA resin on the basis of their distribution coefficient at various pH were also achieved using column chromatography. The effect of experimental parameters such as pH, treatment time, agitation speed, temperature, adsorbent dose, initial metal ion concentration, and flow rate on the removal of metal ions has been also studied. GHBA resin is effective adsorbents for the removal of different toxic metal ions from aqueous solutions and follows the order: Fe2+ &gt; Zn2+ &gt; Cu2+ &gt; Cd2+ &gt; Pb2+. POLYM. ENG. SCI. 2013. © 2012 Society of Plastics Engineers

Synthesis, characterization of a new tamarind based ion exchange resin and use for the separation of heavy metal ions in industrial wastewater

Synthesis, characterization of a new tamarind based ion exchange resin and use for the separation of heavy metal ions in industrial wastewater

Selective transport of zinc and copper ions by synthetic ionophores using liquid membrane technology

This work highlights the role of synthetic carrier (ionophore) in the separation of heavy metal ions. A new series of ionophores; 4,4′-nitrophenyl-azo-O,O′-phenyl-3,6,9-trioxaundecane-1,10-dioate (R1), bis[4,4′nitro-phenylazo-naphthyl-(2,2-dioxydiethylether)] (R2) 1,8-bis-(2-naphthyloxy)-3,6-dioxaoctane (R3), 1,11-bis-(2-naphthyloxy)-3,6,9-trioxaunde-cane (R4), 1,5-bis-(2-naphthyloxy)-3-oxa-pentane (R5) have been synthesized and used as extractant as well as carrier for the transport of various metal ions (Na+, K+, Mg2+, Ni2+, Cu2+ and Zn2+) through liquid membranes. Effect of various parameters such as metal ion concentration, ionophore concentration, liquid–liquid extraction, back extraction, comparison of transport efficiency of BLM and SLM and different membrane support (hen’s egg shell and PTFE) have been studied. In BLM ionophores (R2–R5) transport Zn+ at greater extent and the observed trend for the transport of Zn2+ is R2 > R4 > R3 > R5 respectively. Further transport efficiency is increased in SLM. In egg shell membrane ionophores (R2–R5) transport Zn+ due to their non-cyclic structure and pseudo cavity formation while ionophore R1 transports Cu2+ ions at greater extent due to its cyclic structure and cavity size. Among the membrane support used egg shell membrane is found best for the transport of zinc ions because of its hydrophobic nature and exhibits electrostatic interactions between positively charged zinc ions and –COOH group of egg shell membrane. Thus structure of ionophores, hydrophobicity and porosity of the membrane support plays important role in separation of metal ions.

Synthesis and characterization of nano-composite ion-exchanger; its adsorption behavior

A novel organic-inorganic nanocomposite cation-exchanger has been synthesized via sol-gel method. It was characterized on the basis of FTIR, XRD, SEM, TEM, AFM and Raman studies. The structural studies reveal semi-crystalline nature of the material with the particle size ranging from 1-5 nm. Physiochemical properties such as ion-exchange capacity, chemical and thermal stability of composite material have also been determined. Bifunctional behavior of the material has been indicated by its pH titrations curves. The nanocomposite material exhibits improved thermal stability, higher ion-exchange capacity and better selectivity for toxic heavy metals. The ion-exchange material shows an ion-exchange capacity of 1.8 meq g(-1) for Na(+) ions. Sorption behavior of metal ions on the material was studied in different solvents. The cation exchanger was found to be selective for Pb(II), Hg(II) and Zr(IV) ions. The limit of detection (LOD) and the limit of quantification (LOQ) for Pb(II) ion was found to be 0.85 and 2.85 μg L(-1). Analytically important separations of heavy metal ions in synthetic mixtures as well as industrial effluents and natural water were achieved with the exchanger. The practical utility of polyanilineZr(IV)sulphosalicylate cation exchanger has been established for the analysis and recovery of heavy metal ions in environmental samples.

Functionalization of microcapsules for the removal of heavy metal ions

BACKGROUND: Solvent extraction and ion exchange technologies have been widely used for the recovery or removal of heavy metals from aqueous phases. However, different problems have been encountered on applying these techniques. Although the extractants are highly selective, this technique requires a high level of mechanical agitation to improve the kinetics of the process, a requirement that promotes leakage of the extractant from the aqueous/organic interface to the aqueous phase during separation of the two phases. On the other hand, ion exchangers can easily be regenerated but gel form resins have low selectivity and those with high selectivity (chelating resins) have low diffusion coefficients, a characteristic that leads to low mass transfer rates. An interesting alternative to overcome these limitations is the microencapsulation of extractants within a functionalized polymeric shell. This new type of material would be expected to combine the advantages of the aforementioned methods and improve selective removal of heavy metals from an aqueous phase. RESULTS: Sulfonation of microcapsules indicated that the use of an ethylene glycol dimethacrylate (EGDMA) copolymer enhances the chemical and mechanical properties of the microcapsules. It was found that the recipe used to produce microencapsulated phase change materials (PCM) was also useful to prepare microcapsules with di(2-ethylhexyl)phosphoric acid (DEHPA) as a core material. The synthesized material had a spherical and smooth shape and a DEHPA content of 28.15 wt%. Finally, the ion exchange capacity of the sulfonated material containing DEHPA (3.02 meq g−1) was higher than that obtained without this additive (2.54 meq g−1). High selectivity for copper uptake was also achieved. CONCLUSIONS: Microcapsules containing extractants can be manufactured by the same approach used to produce microcapsules containing PCMs. In addition, particles with improved chemical and mechanical resistance to sulfonation can be synthesized using EGDMA as a crosslinker. Ion exchange studies showed that the presence of DEHPA enhances the ion exchange capacity and selectivity of the microcapsules. Thus this material is a promising alternative for the separation of heavy metal ions. Copyright © 2010 Society of Chemical Industry

Continuous separation of copper ions from a mixture of heavy metal ions using a three-zone carousel process packed with metal ion-imprinted polymer

In this study, a three-zone carousel process based on a proper molecular imprinted polymer (MIP) resin was developed for continuous separation of Cu 2+ from Mn 2+ and Co 2+. For this task, the Cu (II)-imprinted polymer (Cu-MIP) resin was synthesized first and used to pack the chromatographic columns of a three-zone carousel process. Prior to the experiment of the carousel process based on the Cu-MIP resin (MIP-carousel process), a series of single-column experiments were performed to estimate the intrinsic parameters of the three heavy metal ions and to find out the appropriate conditions of regeneration and re-equilibration. The results from these single-column experiments and the additional computer simulations were then used for determination of the operating parameters of the MIP-carousel process under consideration. Based on the determined operating parameters, the MIP-carousel experiments were carried out. It was confirmed from the experimental results that the proposed MIP-carousel process was markedly effective in separating Cu 2+ from Mn 2+ and Co 2+ in a continuous mode with high purity and a relatively small loss. Thus, the MIP-carousel process developed in this study deserves sufficient attention in materials processing industries or metal-related industries, where the selective separation of heavy metal ions with the same charge has been a major concern.

Characterization and ion-exchange behavior of thermally stable nano-composite polyaniline zirconium titanium phosphate: Its analytical application in separation of toxic metals

A ‘polymeric-inorganic’ advanced nano-composite cation-exchanger has been synthesized via sol–gel technique by incorporating polyaniline into inorganic ion-exchanger, zirconium titanium phosphate, a class of mixed material of tetravalent bimetallic acid salts (TMA). The composite shows extraordinary high ion-exchange capacity of 4.52 meq g −1 as well as good chemical and thermal stability than other polyaniline composites prepared so far. The physico-chemical property of the composite, polyaniline zirconium titanium phosphate (PAZTP) was determined using AAS, TEM, SEM, FTIR and TGA-DTA studies. Ion-exchange behavior was also observed to characterize the material. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ions Hg(II) and Pb(II). The analytical applications of the material have been explored by achieving some binary as well as ternary separations of heavy metal ions. A comparative study of the ion-exchange properties of PAZTP with other polyaniline composites has been done.

Bioremediation of soluble heavy metals with recombinant Caulobacter crescentus

To achieve one-step separation of heavy metal ions from contaminated water, we have developed a novel bioremediation technology based on self-immobilization of the Caulobacter crescentus recombinant strain JS4022/p723-6H, which overexpresses hexahistidine peptide on the surface of the bacterial cells and serves as a whole-cell adsorbent for dissolved heavy metals. Biofilms formed by JS4022/p723-6H are effective at retaining cadmium from bacterial growth media or environmental water samples. Here we provide additional experiment data discussing the application potential of this new technology. Supplementation of calcium to the growth media produced robust JS4022/p723-6H cells by alleviating their sensitivity to chelators. After growth in the presence of 0.3% CaCl2⋅2H2O, double the amount of JS4022/p723-6H cells survived the treatment with 2 mM EDTA. Free cells of JS4022/p723-6H effectively sequestered 51% of the total cadmium from a Lake Erie water sample at pH 5.4, compared to 37% retrieved by the control strain. Similar levels of adsorption were observed at pH 4.2 as well. Cells of JS4022/p723-6H were tolerant of acid treatment for 90 min at pH ≥1.1 or 120 min at pH ≥2.5, which provides an avenue for the convenient regeneration of the bacterial cells with acidic solutions. Designs of possible bioreactors and an operation system are also presented.