Chelating Adsorbent Research Articles

Removal of heavy metals from water effluents using supermacroporous metal chelating cryogels

Applications of IDA in, for example, immobilized metal ion affinity chromatography for purification of His-tagged proteins are well recognized. The use of IDA as an efficient chelating adsorbent for environmental separations, that is, for the capture of heavy metals, is not studied. Adsorbents based on supermacroporous gels (cryogels) bearing metal chelating functionalities (IDA residues and ligand derived from derivatization of epoxy-cryogel with tris(2-aminoethyl)amine followed by the treatment with bromoacetic acid (defined as TBA ligand)) have been prepared and evaluated on capture of heavy metal ions. The cryogels were prepared in plastic carriers, resulting in desired mechanical stability and named as macroporous gel particles (MGPs). Sorption and desorption experiments for different metals (Cu²+, Zn²+, Cd²+, and Ni²+ with IDA adsorbent and Cu²+ and Zn²+ with TBA adsorbent) were carried out in batch and monolithic modes, respectively. Obtained capacities with Cu²+ were 74 μmol/mL (TBA) and 19 μmol/mL gel (IDA). The metal removal was higher for pH values between pH 3 and 5. Both adsorbents showed improved sorption at lower temperatures (10°C) than at higher (40°C) and the adsorption significantly dropped for the TBA adsorbent and Zn²+ at 40°C. Desorption of Cu²+ by using 1 M HCl and 0.1 M EDTA was successful for the IDA adsorbent whereas the desorption with the TBA adsorbent needs further attention. The result of this work has demonstrated that MGPs are potential treatment alternatives within the field of environmental separations and the removal of heavy metals from water effluents.

Preparation of monolithic chelating adsorbent inside a syringe filter tip for solid phase microextraction of trace elements in natural water prior to their determination by ICP-MS

A syringe-based sample pretreatment tool, named herein "tip-in chelating monolith", has been developed for simple and facile solid phase microextraction (SPME) of trace elements in natural waters. The tip-in chelating monolith was directly prepared within the confines of a commercially available syringe filter tip by a two-step process: (1) in situ polymerization of a monomer solution consisting of 22.5% glycidyl methacrylate (GMA), 7.5% ethylene glycol dimethacrylate (EDMA), 35% 1-propanol, 28% 1,4-butanediol, and 7% water and (2) its subsequent modification with 1molL(-1) of iminodiacetate solution (adjusted to pH 10) via ring-opening reaction of epoxide. The adsorption properties of the tip-in chelating monolith thus obtained were evaluated through an adsorption/desorption experiment, where the effects of sample solution pH and eluent on the SPME of trace metals and metalloids were systematically examined. Consequently, when sample solution pH was adjusted to 5.0 and 0.9mL of 2molL(-1) nitric acid was used as an eluent, good recoveries of more than 80% were obtained for 27 elements in a single-step extraction. The proposed SPME method was validated through the analysis of two river water certified reference materials (CRMs: JSAC 0301-1 and NMIJ 7201-a). After 50-fold preconcentration (from 50mL of the original river water sample to 1.0mL of final analysis solution), 22 trace elements including Ti, Fe, Co, Ni, Cu, Ga, Cd, Sn and REEs were quantitatively determined by inductively coupled plasma mass spectrometry (ICP-MS). The analytical detection limits were in the range from 0.000003microgL(-1) for Ho to 0.18microgL(-1) for Fe. Good agreement of the observed values with the certified or reference values indicates that the proposed SPME using the tip-in chelating monolith is practically applicable.

Preparation and chelation adsorption property of composite chelating material poly(amidoxime)/SiO 2 towards heavy metal ions

Micron-sized silica gel particles were first surface-modified with coupling agent, γ-methacryloylpropyl trimethoxysilane (MPS), introducing polymerizable double bonds into the surfaces of silica gel particles, and then acrylonitrile (AN) was graft-polymerized in the manner of “grafting from”, resulting in the grafted particles PAN/SiO 2. In succession, the grafted PAN was transformed into the grafted poly(amidoxime) (PAO) via amidoximation transformation reaction with hydroxylamine hydrochloride as reaction reagent, and the composite chelating particles PAO/SiO 2 were obtained. In this work, the chelating adsorption property and mechanism of PAO/SiO 2 particles towards heavy metal ions were mainly investigated, and the adsorption thermodynamics was also researched. The experiment results show that PAO/SiO 2 particles possess strong chelating adsorption ability for heavy metal ions, for example, the saturated adsorption amounts of Pb 2+ and Cu 2+ ions on PAO/SiO 2 particles can get up to 12 and 10 g/100 g, respectively. The adsorption of PAO/SiO 2 towards heavy metal ions is an endothermic chemical adsorption process driven by entropy, and the adsorption capacity increases with raising temperature. The adsorption property of PAO/SiO 2 is dependent on the pH value of the medium, and in a certain pH range, the adsorption ability is strengthened with increasing pH value. The adsorption of PAO/SiO 2 for heavy metal ions is selective, and the adsorption capacity is in the order of Cu 2+ ≫ Ni 2+ > Pb 2+ > Cd 2+.

Equilibrium and Molecular Mechanism of Anionic Dyes Adsorption onto Copper(II) Complex of Dithiocarbamate-Modified Starch

The assembly of dyes molecules on metal-polymer complexes is of interest due to their potential applications in photovoltaic cell, separation, and wastewater treatment. In the present work, the interaction of anionic dyes (acid orange 7, acid orange 10, acid green 25, and acid red 18) with the copper(II) complex of dithiocarbamate-modified starch (DTCSCu) was investigated. The sorption studies showed that the interaction mechanism was based on chelating adsorption. The equilibrium data fitted well with Langmuir-Freundlich isotherm, and the capacities followed the order AO7 > AG25 > AR18 > AO10. It was affected by the structure of the dye. The sulfonate groups located on benzene rings favored efficient adsorption. Despite the difference in capacity, the molar n(dye):n(Cu) ratios for acid orange 10, acid red 18, and acid green 25 were approximately 1:2 when the maximum capacities for the dyes were achieved at the optimal pH of 4. It suggested that one dye molecule bound to one dinuclear copper center on DTCSCu. The molar n(dye):n(Cu) ratio for the smallest dye, acid orange 7 (AO7), approached 1:1, demonstrating two AO7 molecules binding to two copper ions of the dinuclear core. The dyes adsorption related to the dinuclear copper core available on the polymer was further verified by electron spin resonance studies. Such interaction resulted in the formation of a ternary dye-metal-polymer complex. The ternary complexes were more stable than DTCSCu, which favored the adsorptions.

Selective recovery of histidine-containing dipeptides based on metal affinity interactions using chemically modified dextran in combination with ultrafiltration

A recovery system using metal affinity interactions in combination with ultrafiltration (UF) membrane separation was developed for nutraceutically important histidine-containing dipeptides (HCDPs) such as carnosine (Car) and anserine (Ans). Cu(II)-immobilized, chemically modified dextran bearing an iminodiacetic acid group (Cu(II)IDA-EGDE-Dex) was prepared as a complexing material for HCDPs. After the water-soluble Cu(II)IDA-EGDE-Dex captures Car in an aqueous solution, the complex is separated from the aqueous solution with the UF membrane. The recovery of Car using Cu(II)IDA-EGDE-Dex reaches equilibrium within one hour, which is much faster than metal affinity adsorption using a polystyrene chelating adsorbent. Cu(II)IDA-EGDE-Dex captures Car via metal affinity interactions in the presence of 100 mM NaCl, under which conditions the chemically modified dextran does not capture Car. Histidine and the HCDPs were selectively recovered by Cu(II)IDA-EGDE-Dex from a mixed solution containing Car, Ans and 17 amino acids, and from a model solution of bonito broth. The immobilized Car was efficiently eluted from Cu(II)IDA-EGDE-Dex using acetic acid as an eluent.

Radiation synthesis of amino-functionalizated adsorbent and their application to palladium ions’ recovery

In order to prepare a new type adsorbent with an imine affinity ligand for treatment of Pd ( ▪), polypropylene (PP) fabrics modified with amine were prepared by radiation-induced grafting of acrylonitrile (AN) onto polypropylene fabrics and subsequently amination of poly-AN graft chains. Influence of some parameters such as initial concentration and adsorption time on the absorbed amount for palladium ions was investigated. Results suggested that the chelating adsorbent possessed high-adsorption performance toward palladium ions. The grafted and aminated fabrics were characterized by FT-IR and DSC.

Chelation Adsorption Behavior of a Salicylic Acid-Type Chelate Resin for Fe(III) Ions

The nucleophilic substitution reaction of phenyl chloride groups on chloromethylated cross-linked polystyrene(CMCPS) microspheres was conducted using 5-amino salicylic acid(ASA) as an amination reagent.The resultant product was a salicylic acid-type chelate resin(ASA-CPS).Chelation adsorption behavior of the ASA-CPS resin for metal ions was studied and adsorption thermodynamics as well as the adsorption mechanism was also investigated.The effect of medium pH on adsorption of the ASA-CPS resin was examined and the chelation adsorption abilities of ASA-CPS for different metal ions were tested.Experimental results show that the salicylic acid-type chelate resin,ASA-CPS,possesses strong chelation adsorption ability for heavy metal ions.The resin is especially good at adsorbing Fe(III) ions and the adsorption capacity can reach 21 g/100 g at room temperature.Adsorption is a process driven by entropy and higher temperatures facilitate the adsorption process and thus increase the adsorption capacity.In the pH range where the hydrolysis of metal ions is inhibited,an increase in the pH value of the medium will strengthen the chelation adsorption ability of the ASA-CPS resin for heavy metal ions.For different metal ions,ASA-CPS exhibits different adsorption abilities with the following order of adsorption capacity: Fe3+Ni2+Cu2+Zn2+.

The modification of quantum dot probes used for the targeted imaging of his-tagged fusion proteins

In molecular biology and protein detection the immobilized metal ion clusters using a NTA-chelator is a powerful technique in identification and isolation of histidine-tagged fusion proteins. The Oligo-histidine tag should serve as a high affinity binding sequence for the purification of any fusion protein via metal chelating adsorbents. We described the preparation and characterization of bioinorganic conjugates made with highly luminescent semiconductor CdTe–CdS core–shell quantum dots (QDs) for biological labeling. A biocompatible surface-functionalized nanoparticle was designed to sense histidine-tagged fusion proteins. This study demonstrates the synthesis of Ni–NTA conjugated QD nanoparticles and the successful application of these nanoparticles to the detection of histidine-tagged fusion proteins. It is believed that this approach will provide a more convenient methodology for the intracellular localization of histidine-tagged protein, as compared with current methods. These Ni–NTA–QD clusters were shown to target the 6 x histidine region of tagged proteins specially.

Thermally robust chelating adsorbents for the capture of gaseous mercury: Fixed-bed behavior

Thermally robust chelating adsorbents for the capture of vapor-phase mercuric chloride (HgCl 2) have been developed, to address the issue of mercury removal from flue gases from coal-fired power plants. The adsorbents are mesoporous silica substrates functionalized with a chelating agent and coated with an ionizing surface nano-layer. This architecture enables selective, multi-dentate adsorption of mercury directly from the gas phase with high capacity. The capture efficiency of the adsorbents was evaluated in the fixed-bed mode for oxidized mercury at 160 °C. Two chelating adsorbents, one functionalized with 3-mercaptopropyltrimethoxysilane (MPTS) and the other with 2-mercaptobenzothialzole (MBT), were studied. For both adsorbents a high mercury uptake capacity was observed, several times higher than that of commercial activated carbon. The mechanism for mercury uptake in the two adsorbents is different. The effect of pore size on uptake was also evaluated. It was found that pore size does not have a significant effect on the mercury adsorption, and mercury diffusion through the ionic coating is believed to be the rate-limiting step for capture.

Room Temperature Ionic Liquids for Mercury Capture from Flue Gas

Six room temperature ionic liquids (RTILs) were synthesized and tested as coatings for adsorbents for mercury capture from nitrogen at 160 °C. All six RTILs were thermally stable to temperatures above 160 °C. These RTILs were coated on mesoporous silica gel, and the fixed-bed mercury capture characteristics of these adsorbents were observed at 160 °C. Hg0 capture appears to result from the formation of a complex involving Hg0 and ions in the RTIL complex, and not from oxidation by the RTIL. The high observed oxidized mercury capacity for Cl−-based RTILs is believed to be due to greater dissociation of HgCl2 in the RTILs that incorporate chloride anion. The higher hydrogen-bond basicity and dipolarity of these RTILs might underlie improved HgCl2 dissociation. [bmim]Cl was identified as a promising RTIL for the simultaneous capture of elemental and oxidized mercury from the gas phase. A nanostructured chelating adsorbent with a coating of 25 wt % [bmim]Cl has an elemental mercury capacity of 10 mg/g and an oxidized mercury capacity of at least 38 mg/g.

Removal of copper and nickel from concentrated ZnSO 4 solutions with silica-supported chelating adsorbents

The removal of copper and nickel from concentrated zinc sulfate solutions using two different silica-supported chelating adsorbents (designated as WP-1 and CuWRAM) was studied. The WP-1 adsorbent contains branched poly(ethyleneimine) anchored on silica and in CuWRAM the anchored polyamine is further functionalized with 2-(aminomethyl)pyridine groups. Binding equilibrium data of sulfuric acid and metal sulfate with these two adsorbents were obtained from batch adsorption measurements. A non-ideal competitive adsorption (NICA) model was used for data correlation. The estimated equilibrium parameters were utilized in a dynamic column model to calculate the break-through curves of mixed metal sulfate solutions. Results of the adsorption column runs show that the selectivity of CuWRAM and WP-1 is sufficient for a feasible separation of copper in the presence of 250-fold zinc excess. Only partial separation of nickel is possible due to the lower uptake selectivity and the very high Zn/Ni feed ratio of 12,000. WP-1 must be used in unprotonated form because of its basicity and fixed-bed operation becomes difficult because of the precipitation of basic metal sulfates. Separation with a protonated adsorbent prevents precipitation but the metal uptake capacity is very low. Due to the lower basicity of the ligand groups of CuWRAM, competitive adsorption of metals is more favorable and similar uptake capacities are attained in acid-form as with unprotonated WP-1. The results of the separation runs are discussed on the basis of equilibrium and kinetic data measured with individual metals. The experimental data are compared with the calculated results and a satisfactory agreement is found for the break-through behavior of copper in CuWRAM and WP-1.

Recent Patents on Polymeric Adsorbents and their Derivatives for Pollutants Removal from Aqueous Media: A Mini-Review

Water pollution by organic and/or inorganic pollutants has gained considerable attention all over the world. In the past decades, adsorption has been proposed as one of the most effective and simplest approaches to remove pollutants from contaminated waters, and polymer-based adsorbents have been widely used as efficient adsorbents except for activated carbon. Here, we reviewed recent patents on preparation of polymeric adsorbents and their derivatives as well as their application in pollutants removal from waters. Here, we classify the polymer-based adsorbents as four types for review: polymeric porous adsorbents; their chemically modified derivatives, polymer-coated inorganic hybrid adsorbents, and polymeric chelating adsorbents. Some of the features on their preparation, properties, and applications were illustrated by case studies. The forthcoming development in the given field was also discussed.

Adsorption of zinc on polymeric chelating adsorbents in the analysis of natural water

The physicochemical and analytical properties of polymeric chelating adsorbents, polystyrene-2-hydroxy-(1-azo-1′)-2′-hydroxybenzene derivatives, to zinc ions were studied. A possible chemical mechanism of the complexation process was based by a number of parameters. A procedure was proposed for the preconcentration of zinc followed by its stripping voltammetric determination in natural water. The detection limit of the proposed procedure (0.1 μg/L) ensures reliable ecological control of natural waters; the relative standard deviation was 1–4% at a concentration level of n × 10−5%.

Removal of cadmium from scallop processing waste by washing with weak acid solution and utilization of useful constituents for organic fertilizer manufacturing

Hepatopancreases were washed four times with 2% acetic acid solution. In both the washed hepatopancreases and the supernatant of the washing solution, the residual cadmium (Cd) concentration was in accordance with the required standard for organic fertilizers. Hepatopancreases do not naturally contain high levels of nitrogen, but they do contain several amino acids which are useful for cultivation, and these were retained during the washing process. Although the condensed precipitate of the washing solution contained a considerable amount of Cd, Cd elution levels at the time of final disposal met judgment standard for special management industrial waste as a result of kneading and immobilizing with chelating adsorbent for treatment of contaminated soil. The volume of the precipitate of the washing solution was one-fifth of the original hepatopancreas, and the solid waste was suitable for burial at a final disposal site without further treatment.

A Study of the Interaction of HEK-293 Cells with Streamline Chelating Adsorbent in Expanded Bed Operation

Expanded bed adsorption (EBA) is an efficient protein purification process reducing time and steps of downstream processing (DSP) since nonclarified culture media can be processed directly without prior treatments such as filtration or centrifugation. However, cells and debris can interact with the adsorbent and affect bed stability as well as purification performance. To optimize EBA operating conditions these biomass/adsorbent interactions have to be understood and characterized. The adsorption of Human Embryonic Kidney cells (HEK 293) on unprimed and nickel-primed metal affinity adsorbent was studied in a closed loop EBA setup. With the unprimed adsorbent, the overall level of interaction observed was nonsignificant. With the nickel-primed adsorbent and an initial cell concentration ranging from 0.08 x 10(6) to 0.2 x 10(6) cells/mL, biomass/adsorbent interaction was found to be moderate and the adsorption apparent first-order kinetic rate constant was determined to be k = 0.009 to 0.011 min(-1).

Pyrrolidinium Imides: Promising Ionic Liquids for Direct Capture of Elemental Mercury from Flue Gas

A new approach to vapor phase elemental mercury capture has been explored; this approach exploits an ionic liquid coating layer to oxidize elemental mercury for subsequent immobilization by chelating ligands. The room temperature ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane sulfonyl)imide (P14) was selected for study based on its oxidation potential window, thermal stability, and low vapor pressure. Tests were also completed in which KMnO4 was added to P14 to form a new ionic liquid, P14–KMnO4, with a higher oxidation potential. In room-temperature bulk liquid phase capture experiments, 59% of the elemental mercury in the inlet gas was captured using P14 alone; mercury capture using P14–KMnO4 was quantitative. P14 and P14–KMnO4 coatings were successfully applied to mesoporous silica substrates and to silica substrates functionalized with mercury chelating ligands. The coating layers were found to be thermally stable up to 300°C. Fixed-bed tests of nonfunctionalized silica coated with P14 showed an elemental mercury uptake of 2.7 mg/g adsorbent at 160°C; at the same temperature, functionalized silica coated with P14–KMnO4 showed an elemental mercury capacity of at least 7.2 mg/g adsorbent, several times higher than that of activated carbon. The empty bed gas residence time in these tests was 0.04 s. A chelating adsorbent incorporating P14 in the coating layer, may be capable of simultaneous removal of elemental and oxidized mercury from coal combustion flue gases.

Spray-dried chitosan microspheres containing 8-hydroxyquinoline -5 sulphonic acid as a new adsorbent for Cd(II) and Zn(II) ions

In the present study, a new chelating adsorbent was prepared from chitosan microspheres cross-linked with glutaraldehyde by spray drying using 8-hydroxyquinoline -5 sulphonic acid as chelant agent (CTS-SX-CL). Microspheres of the new adsorbent were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX). The effect of pH, contact time and concentration of metallic ions in solution were evaluated on the adsorption behavior of Cd(II) and Zn(II) by CTS-SX-CL. Adsorption was maximum for both Cd(II) and Zn(II) at pH 8.0. Adsorption kinetic curves were obtained and could be fit by the pseudo second-order adsorption model. An analysis of equilibrium adsorption data using the Langmuir isotherm model indicated that the maximum adsorption capacity of CTS-SX-CL was higher than that of CTS-CL for both ions investigated. The adsorption capacity increased 74% for Cd(II).

Simultaneous determination of suspended particulate trace metals (Co, Ni, Cu, Zn, Cd and Pb) in seawater with small volume filtration assisted by microwave digestion and flow injection inductively coupled plasma mass spectrometer

A new technique for the determination of suspended particulate trace metals (P–metals >0.2 μm), such as Co, Ni, Cu, Zn, Cd and Pb, in open ocean seawater has been developed by using microwave digestion coupled with flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Suspended particulate matter (SPM) was collected from 500 mL of seawater on a Nuclepore filter (0.2 μm) using a closed filtration system. Both the SPM and filter were completely dissolved by microwave digestion. Reagents for the digestion were evaporated using a clean evaporation system, and the metals were redissolved in 0.8 M HNO 3. The solution was diluted with buffer solution to give pH 5.0 and the metals were determined by FI-ICP-MS using a chelating adsorbent of 8-hydroxyquinoline immobilized on fluorinated metal alkoxide glass (MAF-8HQ). The procedure blanks with a filter were found to be 0.048 ± 0.008, 10.3 ± 0.3, 0.27 ± 0.05, 3.3 ± 1.8, 0.02 ± 0.03 and 0.85 ± 0.09 ng L −1 for Co, Ni, Cu, Zn, Cd and Pb, respectively ( n = 14). Detection limits defined as 3 times the standard deviation of the blanks were 0.023, 0.90, 0.14, 5.3, 0.078 and 0.28 ng L −1 for Co, Ni, Cu, Zn, Cd and Pb, respectively. Accuracy was evaluated using certified reference materials of chlorella (NES CRM No. 3) and marine sediment (HISS-1). The method was applied to the determination of vertical distributions for P–Co, Ni, Cu, Zn, Cd and Pb in the Western North Pacific.

Studies on chelating adsorption properties of novel composite material polyethyleneimine/silica gel for heavy-metal ions

Firstly, the coordination processes of line-type polyethyleneimine with Cu2+, Cd2+ and Zn2+ were studied by using visible light absorption spectroscopy and chelation conductivity titration method, and the structures of the chelates were determined. Afterwards, polyethyleneimine (PEI) was grafted onto the surface of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP), and the novel composite adsorption material PEI/SiO2 with strong adsorption ability towards heavy-metal ions was prepared. The chelating adsorption properties of PEI/SiO2 for Cu2+, Cd2+ and Zn2+ were researched by both static (batch) and dynamic (flow) methods. The experiment results show that water-soluble polyamine PEI with line-type structure reacts with Cu2+, Cd2+ and Zn2+ easily and quantitatively, and water-soluble chelates with four ligands are formed. The composite material PEI/SiO2 possesses very strong chelating adsorption ability for heavy-metal ions, and the saturated adsorption amount can reach 25.94mgg−1 and 50.01mgg−1 for Cu2+ under static and dynamic conditions, respectively. The isothermal adsorption data fit to Langmuir equation, and the adsorption is typical chemical adsorption with monomolecular layer. The adsorbing ability of PEI/SiO2 towards the three kinds of the ions follows the order of Cu2+>Cd2+>Zn2+. The pH value has great influence on the sorption, and at pH 6–7, the adsorption capacity is the greatest. The fact that adsorption capacity increases with temperature rising indicates the adsorbing process of PEI/SiO2 for metal ions is endothermic. As diluted hydrochloric acid is used as eluent, the adsorbed heavy-metal ions are eluted easily from PEI/SiO2, and the regeneration and reuse without decreasing sorption for PEI/SiO2 are demonstrated.

Recovery of histidine-tagged nucleocapsid protein of Newcastle disease virus using immobilised metal affinity chromatography

An immobilised metal affinity packed bed adsorption chromatography (IMA-PBAC) for the purification of recombinant nucleocapsid protein (NP) of Newcastle disease virus (NDV) directly from clarified feedstock was developed. The XK 16/20 (i.d. = 16 mm) was used as a packed bed column and Streamline chelating adsorbent immobilised with Ni 2+ ion was used as IMA adsorbent. This purification method has resulted in a 59% adsorption and 5.6% recovery of NP protein. Adsorbed NP proteins were successfully recovered using a two-step elution protocol which employed elution buffer 1 containing 50 mM imidazole to eliminate contaminating proteins and elution buffer 2 containing 350 mM imidazole to recover the NP protein at pH 8 with flow velocity of 10 cm h −1. About 70% of the adsorbed NP protein was eluted. The purity of the recovered NP protein was about 70% and the volume of processing fluid was reduced by a factor of 4. The antigenic features of purified NP proteins were confirmed by enzyme-linked immunosorbent assay (ELISA) analysis.