New hydrogel containing sulfur compound prepared by γ irradiation and its application for metal recovery

A new hydrogel that contains sulfur is prepared by radiation polymerization and its application for recovery of Hg²⁺, Pb²⁺, Cd²⁺, and Cu²⁺ ions is discussed. The metal hydrogel complexes are isolated and characterized by using different spectroscopic techniques (UV‐visible, IR, NMR, and mass), thermal analysis (TGA and DSC) measurements, and SEM. Also, the mode of complexation is determined using IR and NMR spectroscopy. The scanning electron micrographs show that the hydrogel has a great ability to recover the metal ions in the following order: Hg²⁺ > Cd²⁺ > Pb²⁺ > Cu²⁺. TGA thermograms are used to investigate the mechanism of thermal decomposition. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 955–966, 2000     

Preparation and adsorption properties of metal ions of crosslinked chitosan azacrown ethers

The novel azacrown ether chitosan derivatives (CCAE‐I, CCAE‐II) were prepared by reaction between crosslinked chitosan with epoxy‐activated azacrown ethers. Their structures were confirmed by elemental FTIR spectra analysis and X‐ray diffraction analysis. The adsorption and selectivity properties of the crosslinked chitosan azacrown ethers for Pb²⁺, Cu²⁺, Cr³⁺, Cd²⁺, and Hg²⁺ were also investigated. The experimental results showed that they have high adsorption capacity for Cu²⁺, Cd²⁺, and Hg²⁺. The adsorption capacity of CCAE‐II is higher than CCAE‐I for Cd²⁺ and Hg²⁺. The selectivity properties of CCAE are better than chitosan and crosslinked chitosan. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3053–3058, 1999     

Chelation ion‐exchange properties of copolymer resin derived from 4‐hydroxyacetophenone,oxamide, and formaldehyde

A copolymer (4‐HAOF) prepared by condensation of 4‐hydroxyacetophenone and oxamide with formaldehyde in the presence of an acid catalyst proved to be a selective chelating ion‐exchange copolymer for certain metals. Chelating ion‐exchange properties of this copolymer were studied for Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, and Hg²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal‐ion uptake involving the measurements of the distribution of a given metal ion between the copolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymer showed a higher selectivity for Fe³⁺ ions than for Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺, Ni²⁺, and Hg²⁺ ions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 787–790, 2003     

Binding of heavy metal ions by formaldehyde-polymerized peanut skins

Peanut skin, when treated with formaldehyde to polymerize tannins, is a highly efficient substrate for removal of many heavy metal ions from aqueous waste solutions. The ions Ag¹⁺, Cd²⁺, Cr⁶⁺, Cu²⁺, Hg²⁺, Ni²⁺, Pb²⁺, Zn²⁺, as well as Ca²⁺ and Mg²⁺, were contacted with formaldehyde-treated peanut skin. Quantitative removal could be achieved with Ag¹⁺, Cd²⁺, Cu²⁺, Hg²⁺, Pb²⁺, and Zn²⁺. Capacity of the substrate for ions was promising for Pb²⁺ (2.1 meq/g substrate), Cu²⁺ (3.0 meq/g), and Cd²⁺ (1.3 meq/g). Sorption from a solution containing Cd²⁺, Cu²⁺, Hg²⁺, Ni²⁺, Pb²⁺, Zn²⁺, on a packed column of formaldehyde-treated peanut skin indicated that Hg²⁺, Pb²⁺, and Cu²⁺ were rapidly and completely bound to the packing, while Cd²⁺, Ni²⁺, and Zn²⁺ were poorly bound until the preferred ions had been removed from solution.     

Sorption Studies of Terpolymers Based on p-Nitrophenol,Triethylenetetramine, and Formaldehyde

Terpolymer resins have been synthesized by condensation of p-nitrophenol, triethylenetetramine, and formaldehyde in the presence of 2 M NaOH as a catalyst with different molar proportions of monomers. Newly synthesized terpolymers were proved to be selective chelation ion exchangers for metal ions like Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺. A batch equilibrium study was carried out over a wide pH range, shaking time, and in media of various ionic strengths of different electrolytes and shows higher selectivity for Hg²⁺, Cd²⁺, and Pb²⁺. Distribution ratios of metal ions were found to be increased by increasing pH of solutions; hence the resins can be used to recover certain metals from waste solutions and removal of iron from boiler water.     

Characterization and adsorption behavior of newly synthesized sodium bis(2-ethylhexyl) sulfosuccinate–cerium (IV) phosphate (AOT–CeP) cation exchanger

A new cationic exchange material, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) with cerium (IV) phosphate (AOT–CeP) has been synthesized. The characterization of the ion exchanger was performed by using infra red spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo gravimetric analysis/differential thermo gravimetric analysis (TGA/DTA/DTG) and elemental analysis. The ion exchange properties like ion exchange capacity, elution and concentration behavior of AOT–CeP were determined by taking the material into a column and elution of H⁺ was done by NaNO₃. The thermal stability of the ion exchanger was studied by determining ion exchange capacity after heating to different temperatures for one hour. The adsorption studies on AOT–CeP demonstrated that the material is selective for Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions. AOT–CeP was found to be effective for the separation of Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions in the presence of alkali metals/alkaline earth metals. This cationic exchanger was also effective for the removal of Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions in the presence of acid and other transition metal ions. Thus, AOT–CeP can be used for the removal of these ions from the waste water during its treatment.     

Synthesis and evaluation of chitosan aryl azacrown ethers as adsorbents for metal ions

New azacrown ether chitosan derivatives (CTS–OC, CTS–NC) were synthesized by reaction of aryl mesocyclic diamine with the C6 hydroxyl group or C2 amino group in chitosan. Their structures were confirmed by elemental analysis, infrared spectra analysis, and X‐ray diffraction analysis. The adsorption and selectivity properties of the aryl azacrown ethers chitosan derivatives for Hg²⁺, Cd²⁺, Pb²⁺, Ag⁺, and Cr³⁺ were also investigated. The experimental results showed that the two chitosan–azacrown ethers have good adsorption capacity for Pb²⁺, Cd²⁺, and Hg²⁺. The adsorption capacity of CTS–OC are higher than that of CTS–NC for Pb²⁺ and Cd²⁺. The chitosan–azacrown ethers have high selectivity for the adsorption of Pb²⁺ and Hg²⁺ with the coexistence of Cd²⁺. The selectivity properties of CTS–OC are better than those of CTS–NC. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3093–3098, 2000     

A new rhodamine-based single molecule multianalyte (Cu, Hg) sensor and its application in the biological system

A new single molecule multianalyte sensor, vanillic aldehyde rhodamine 6G hydrazone has been designed for the selective detection of Cu²⁺ and Hg²⁺ ions. UV/Vis spectroscopy indicates that the sensor is a good chromogenic chemosensor for Cu²⁺ in 1:99 (v/v) ethanol-water media. Whereas, other ions, such as Li⁺, Na⁺, Mg²⁺, K⁺, Ca²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺, Ag⁺, Cd²⁺, Ba²⁺, Hg²⁺ and Pb²⁺ failed to generate a distinct response. Fluorescence spectral data reveals that the sensor is an excellent fluorescent chemosensor for Hg²⁺ in aqueous ethanol solution and with no fluorescent response toward other ions. The spectroscopic behavior of the sensor in living cells indicated that it can be used for the detection of Cu²⁺ and Hg²⁺ in environmental and biological systems. Mechanisms for the high selectivity of the sensor to Cu²⁺ and Hg²⁺ are discussed.     

New Heavy Metal Ion‐Selective Macrocyclic Ligands with Nitrogen and Sulfur Donor Atoms and their Extractant Properties

Abstract

Two new macrocyclic ligands, containing nitrogen and sulfur donor atoms were designed and synthesized in a multi‐step reaction sequence. The macrocycles with amide group were used in solvent extraction of picrates of metals such as Ag⁺, Hg²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Mn²⁺, Co²⁺ and Pb²⁺ from aqueous phase to the organic phase. The metal picrate extractions were investigated at 25±0.1°C by using UV‐visible spectrometry. The extractability and selectivity of the mentioned metal picrates were evaluated according to the organic solvents. The values of the extraction constants (log K_ex) and the complex compositions were determined for the extracted complexes.     

Synthesis of a highly selective bis-rhodamine chemosensor for naked-eye detection of Cu ions and its application in bio-imaging

A bis-rhodamine based fluorescent chemosensor for naked-eye detection of Cu²⁺ with enhanced sensitivity as compared to mono-rhodamine derivative has been synthesized, and its selectivity for Cu²⁺ in the presence of other competitive metal ions (Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺), and application in bio-imaging are demonstrated.     

ION EXCHANGE PROPERTIES OF THE SULFUR-MODIFIED BIOTITE

ABSTRACT

The ion exchange behavior of a sulfur-modified biotite towards Pb²⁺, Hg²⁺, Co²⁺, Cu²⁺, Cd²⁺ and Zn²⁺ ions has been studied. The ion exchange isotherms of divalent cations were determined and concentration equilibrium constants as a function of metal loading were analyzed. Sulfur modified biotite exhibits high affinity for Hg²⁺, Pb²⁺, Cu²⁺ and Cd²⁺ ions in individual solutions and in the presence of electrolytes. About 200 mg Hg/g uptake in 1·10^?3 M Hg²⁺ solution and ～ 35 mg Hg/g in groundwater simulant or an alkaline simulant 2 M in NaN0₃ + 1 M in NaOH was found. The possibility of a complex ion exchange and precipitation mechanism of the sulfur modified biotite towards the soft cations is proposed.     

Functionalized nanostructured silica by tetradentate-amine chelating ligand as efficient heavy metals adsorbent : Applications to industrial effluent treatment

Organofunctionalized nanostructured silica SBA-15 with tri(2-aminoethyl)amine tetradentate-amine ligand was synthesized and applied as adsorbent for the removal of Cu²⁺, Pb²⁺, and Cd²⁺ from both synthetic wastewater and real paper mill and electroplating industrial effluents. The prepared materials were characterized by XRD, N₂ adsorption-desorption, TGA, and FT-IR analysis. The Tren-SBA-15 was found to be a fast adsorbent for heavy metal ions from single solution with affinity for Cu²⁺, Pb²⁺, than for Cd²⁺ due to the complicated impacts of metal ion electronegativity. The kinetic rate constant decreased with increasing metal ion concentration due to increasing of ion repulsion force. The equilibrium batch experimental data is well described by the Langmuir isotherm. The maximum adsorption capacity was 1.85 mmol g^?1 for Cu²⁺, 1.34 mmol g^?1 for Pb²⁺, and 1.08 mmol g^?1 for Cd²⁺ at the optimized adsorption conditions (pH=4, T=323 K, t=2 h, C₀=3 mmol L^?1, and adsorbent dose=1 g L^?1). All Gibbs energy was negative as expected for spontaneous interactions, and the positive entropic values from 103.7 to 138.7 J mol^?1 K^?1 also reinforced this favorable adsorption process in heterogeneous system. Experiment with real wastewaters showed that approximately a half fraction of the total amount of studied metal ions was removed within the first cycle of adsorption. Hence, desorption experiments were performed by 0.3M HCl eluent, and Tren-SBA-15 successfully reused for four adsorption/desorption cycles to complete removal of metal ions from real effluents. The regenerated Tren-SBA-15 displayed almost similar adsorption capacity of Cu²⁺, Pb²⁺, and Cd²⁺ even after four recycles. The results suggest that Tren-SBA-15 is a good candidate as an adsorbent in the removal of Cu²⁺, Pb²⁺, and Cd²⁺ from aqueous solutions.     

Poly (acrylic acid-co-acryloyl tetrasodium thiacalix[4]arene tetrasulfonate) grafted dextrin: new supper metal ion adsorbing hydrogels

Dextrin as a biodegradable natural polymer has hydrophilic nature that capable to increase the swelling properties and biodegradability of the synthetic hydrogels. This study describes the synthesis of a poly (acrylic acid-co-acryloyl tetrasodium thiacalix[4]arene tetrasulfonate) grafted dextrin superabsorbent hydrogels (ADA) via solution polymerization. The effects of acryloyl tetrasodium thiacalix[4]arene tetrasulfonate (ACSTCA) dose (20–60) on swelling properties of the hydrogels were studied. The synthesized hydrogels were characterized by FTIR, TGA, DMTA and rheometry. The metal ion removal capacity of the gels was investigated by atomic absorption for Cd²⁺, Pb²⁺, and Hg²⁺. The tendency of metal ions adsorption decreased in the order of Pb²⁺>Cd²⁺>Hg²⁺. The effect of key operating parameters including ACSTCA content, contact time, adsorbent dosage, solution pH, and crosslinker density was experimentally studied on Pb²⁺ adsorption from aqueous solution. The equilibrium data was analyzed using Langmuir and Freundlich adsorption isotherms. Our experimental data are in best agreement with Freundlich isotherms, and adsorption of metal cation onto hydrogel followed a pseudo second-order kinetic model. According to the thermodynamic parameters, the adsorption of Pb²⁺ occurred spontaneously. The hydrogels could be regenerated after releasing heavy metal ions, and reused 5 times with less than 7 % loss of adsorption capacity.     

Synthesis of a highly selective bis-rhodamine chemosensor for naked-eye detection of Cu2+ ions and its application in bio-imaging

A bis-rhodamine based fluorescent chemosensor for naked-eye detection of Cu²⁺ with enhanced sensitivity as compared to mono-rhodamine derivative has been synthesized, and its selectivity for Cu²⁺ in the presence of other competitive metal ions (Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Sr²⁺, Cr³⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺), and application in bio-imaging are demonstrated.     

Synthesis and Metal‐ion Binding Properties of New N2S4O2‐ and N2S5O2‐Donor Macrocycles

Abstract

Synthetic procedures for new mixed‐donor macrocycle compounds were reported. The macrocyclic compounds were used in solvent extraction metal picrates such as Ag⁺, Hg²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Mn²⁺, Pb²⁺, and Co²⁺. The metal picrate extractions were investigated at 25±0.1°C with the aid of UV‐visible spectrometry. It was found that 6,7,9,10,12,13,23,24‐octahydro‐19H,26Hdibenzo[h,t](1,4,7,13,16,22,10,19) dioxatetrathiadiazasiclotetracosine‐20,27(21H,28H)‐dione showed selectivity towards Ag⁺, Hg²⁺, and Cd²⁺ among the other metals. The extraction constants (Log K_ex) and complex compositions were determined for the Ag⁺ and Hg²⁺ complexes for this compound and 9,10,12,13,23,24,26,27,29,30‐decahydro‐5H,15H‐dibenzo‐[h,w][1,4,7,13,16,19,25‐,10,22] dioxapentathiadiazacycloheptacosine‐6,16(7H,17H)‐dione.     

Sorption of some metal cations by a modified biopolymer based on the mycelium of Penicillium chrysogenum

Summary Three types of a modified biopolymer based on the mycelium of Penicillium chrysogenum were evaluated as to their sorption characteristics for Hg²⁺, Pb²⁺, Cu²⁺ and Cd²⁺. Their useful and total sorption capacities were calculated from their respective breakthrough curves. The highest sorption capacity was recorded for Hg²⁺. Evidence is presented that the retained metals can be easily eluted with diluted mineral acids.     

Binding of several heavy metal ions by polyaspartyl polymers and their application to some Chinese herbal medicines

Water‐insoluble polyaspartyl polymers were synthesized by using water as medium instead of organic medium. Taking Ca²⁺ as a reference, the binding of several heavy‐metal ions, including Pb²⁺, Cd²⁺, Hg²⁺, Cr³⁺, Cu²⁺, and Mn²⁺, by polyaspartyl polymers was studied. The experimental results revealed that polyaspartate is an excellent binding agent for the investigated heavy‐metal ions. These cation ions were bound to polyaspartate polymer by the same mechanism as Pb²⁺, which can be explained by ion exchange model. Since polyaspartate has a protein‐resembling structure that is sensitive to trace heavy metal, it was used to remove some trace heavy‐metal elements in Chinese herbal medicines. It was found that polyaspartate material was an effective agent for the removal of Pb²⁺, Cd²⁺, and Hg²⁺ ions from glycyrrhizin, angelica, and gynostemma pentaphyllum. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation of Chelating Resins Containing a Pair of Neighboring Carboxylic Acid Groups and the Adsorption Characteristics for Heavy Metal Ions

Abstract

For the functional enhancement of chelating resins containing carboxylic acids, copolymer beads were prepared by suspension polymerization of styrene (St), methyl methacrylate (MMA), and divinylbenzene (DVB) in the presence of toluene as diluent. The phenyl rings of the beads were directly chloromethylated, and the carboxylic ester groups of the beads were converted into hydroxymethyl groups by reduction followed by chlorination to give chloromethyl groups, respectively. The chelating resins containing a pair of neighboring carboxylic acid groups (NCAGs) were obtained by the alkylation of chloromethyl groups in copolymer beads with diethyl malonate in the presence of sodium hydride followed by hydrolysis using aqueous alkali solution. Accordingly, the structural effects of the resins on the adsorption of heavy metal ions were investigated. Poly(St‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, and Cu²⁺, whereas poly(MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Cu²⁺, Cd²⁺, and Co²⁺. On the other hand, poly(St‐co‐MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, Co²⁺, and Cu²⁺: a synergistic effect on the adsorption of heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, and Co²⁺ was observed. The adsorption ability of poly(St‐co‐MMA‐co‐DVB)‐based chelating resin among three kinds of chelating resins was relatively good.     

Behavior of acrylic acid–itaconic acid hydrogels in swelling,shrinking, and uptakes of some metal ions from aqueous solution

An experimental research of the absorption properties of metal ions onto synthetic hydrogel obtained by solution polymerization of acrylic acid and itaconic acid in presence of N,N′‐methylenebisacrylamide as crosslinking agent was carried out. The swelling behavior in aqueous salt solutions was studied as a function of divalent cation concentration (Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cd²⁺, Pb²⁺, Hg²⁺) in the external solution ranging from 10^?5 to 1M, at 25°C. The ability of these hydrogels to bind cations was measured at different pH values and metal ion concentrations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 530–536, 2003     

Mechanism of Hg(II), Cd(II) and Pb(II) ions sorption from aqueous solutions by Aspergillus niger spores

ABSTRACT

Recent work has focused on the removal of Pb²⁺, Hg²⁺, and Cd²⁺ by using an organ of Aspergillus niger – spores, which were spherical particles with small diameter (2 µm) characterized by negative charge. Results shown that the biosorption of Pb²⁺, Hg²⁺, and Cd²⁺ from aqueous solutions using spores was analyzed at varying biosorbent dosages, pH levels, contact times and initial heavy metal concentrations. The maximum biosorption capacities of Pb²⁺, Hg²⁺, and Cd²⁺ were 23.9, 27.2, and 21.5 mg/g at a natural pH with the initial concentration were 30 mg/L, respectively. The sequence of biosorption capacity for cationic heavy metals was Pb²⁺>Cd²⁺>Hg²⁺. Spores exhibited a short biosorption equilibrium time of 60 min at a pH range of 4.0–6.0, and the main biosorption mechanism was electronic attraction, ion exchanges and complexation(involved in C = C, C-H, C-O, N-H), the data fit well in the pseudo-second-order kinetic equation and the Freundlich isotherm. In addition, Spores can grow on many kinds of moist agriculture waste without any added nutrition. The results showed that spores could be considered as a potential biosorbent for the removal of cationic heavy metals from aqueous solutions.