Application of a carbon sorbent for the removal of cadmium and other heavy metal ions from aqueous solution

Treatment of flax shive with sulfuric acid produces a carbonaceous material that has been used to remove metal ions from aqueous solution. Metal ions including Cd(II), Cu(II), Cr(III), Co(II), Ni(II), Zn(II) and Pb(II) have been investigated for kinetic behaviour and sorption capacities. These metal ions show fast sorption kinetics following a first order rate equation. Cadmium was chosen as representative of these metal ions and a detailed study was carried out. The effect of pH on sorption was studied and it was found that maximum uptake occurred above pH 3–7, sorption was accompanied by release of protons into the solution and a ratio of [H⁺] released to [Cd²⁺] sorbed of approximately 2 was found. The sorption capacity showed no significant increase with increase of temperature. The presence of other metal ions such as K⁺, Na⁺, Mg²⁺ and Ca²⁺ decreases the Cd(II) capacity, indicating competition for the ion exchange sites. Successive sorption of Cd(II) shows that the capacity exceeds the monolayer capacity calculated from the Langmuir equation. Column studies showed good performance over a total of seven cycles of loading/stripping. These studies indicate that the sorption mechanism for these metal ions is related to a reversible ion exchange process on the carbon surface. © 2002 Society of Chemical Industry     

Preparation,Infra-red,MAS-NMR and Structural Characterization of a New Copper Based Inorganic–Organic Hybrid Compound: [C<Subscript>5</Subscript>H<Subscript>6</Subscript>N<Subscript>2</Subscript>Cl]<Subscript>2</Subscript>CuCl<Subscript>4</Subscript>

The ionic salt [2(C₅H₆N₂Cl)⁺], [CuCl₄]^2? complex of copper(II) has been synthesized and characterized. The X-ray diffraction analysis with a single crystal of this compound showed that the title compound (4-amino-2-chloropyridinium)₂CuCl₄ [(CAP)₂CuCl₄], crystallized at room temperature in the monoclinic system, space group C_2/c (N°.15) and the following : a = 16.0064 (2) Å; b = 7.7964 (10) Å; c = 14.7240 (2) Å; β = 102.497 (10)°; V = 1793.91 (4) ų and Z = 4. The structure was solved by using 1,589 independent reflections down to R value of 0.021. The unit cell is made up of tetrachlorocuprate(II) anions and 4-amino-2-chloropyridinium cations linked together by an extensive hydrogen bond network of types N–H···Cl (N: pyridinium) and N–H···Cl (N: amine), and cation-lone pair of nitrogen element interactions. Solid state NMR spectra showed one and five isotropic resonances, ⁶³Cu and ¹³C, respectively, confirming the solid state structure determined by X-ray diffraction. Impedance spectroscopy study, reported for single crystal, revealed that the conduction in the material was due to a hopping process. This work aims to reveal the thermal properties of a new copper(II) based organic–inorganic hybrid and the conductivity properties that these compounds exhibit.     

Complete Li+ exchange into zeolite X (FAU, Si/Al = 1.09) from undried methanol solution

Complete exchange of Li⁺ into zeolite Na-X, |Na₉₂|[Si₁₀₀Al₉₂O₃₈₄]-FAU, was accomplished using undried methanol solvent (water concentration 0.02 M). A crystal of Na-X was treated with 0.1 M LiNO₃ in the solvent at 333 K, followed by vacuum dehydration at 673 K and 1 × 10^?6 Torr for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques, in the cubic space group $ Fd\overline{3} $ at 100(1) K. The 92 Li⁺ ions per unit cell are found at three different crystallographic sites. The 32 Li⁺ ions occupy at site I’ in the sodalite cavity: these Li⁺ ions are recessed 0.28 Å into the sodalite cavity from their 3-oxygens plane [Li–O = 1.903(5) Å and O–Li–O = 117.8(3)°]. Another 32 Li⁺ ions are found at site II in the supercage, being recessed 0.26 Å into the supercage [Li–O = 1.968(5) Å and O–Li–O = 118.3(3)°]. The remaining 28 Li⁺ ions are located at site III in the supercage [Li–O = 2.00(8) Å].     

Kinetic and thermodynamic effects during the adsorption of heavy metals on ETS-4 and ETS-10 microporous materials

ETS-10 and ETS-4 microporous materials were synthesized in presence of tetralkylammonium (TAA) ions from gels of molar composition w Na₂O–0.10 TAABr–1 SiO₂–z TiO₂–0.6 KF–1.28 w HCl–39.5 H₂O with TAA = tetramethyl-, tetraethyl-, tetrapropyl- and tetrabutyl-ammonium in hydrothermal conditions at 190 °C. The TAA ions enter the microporous channel of ETS-10, while they cannot penetrate the void spaces of ETS-4. The ETS-10 microcrystals are all cubic, while the ETS-4 crystals are laminar and irregular. The microporous volume of ETS-10 is equal to 0.11–0.13 cm³ g^?1, the microporous volume of ETS-4 is very small, 0.002–0.008 cm³ g^?1. The ion exchange of Cs⁺, Cd⁺⁺, Pb⁺⁺ and Hg⁺⁺ ions using their corresponding nitrates show kinetic effects, i.e. the efficiency of ion exchange is higher at 1 than 2 h, the thermodynamic equilibrium. For ETS-10, partially dehydrated cations intervene in the ion exchange, while for ETS-4 well dehydrated ions can only penetrate the available pores.     

Synthesis of organoclays and their application for the adsorption of phenolic compounds from aqueous solution

Organoclays were synthesized by exchanging inorganic cations between layers in Thanh Hoa bentonite using organic cations including benzylhexadecyldimethylammonium (BHDDM⁺), dimethyldioctadecylammonium (DMDOD⁺) and benzylstearyldimethylammonium (BSDM⁺). Inserting organic cations increases material interlayer distance significantly (from 15 Å to 40 Å) and simultaneously enhances affinity of materials toward organic pollutants. The results show that adsorption capacity of organics on organoclays strongly depends on affinity between organic substances and ammonium cations rather than on interlayer distance of organoclays. This means that the sorption of organoclays for organic contaminants was significantly influenced by the nature of the surfactants added to the clay.     

Introducing copper ions into zeolite Y by the thallous ion exchange method: single crystal structure of |Cu21.6Tl39.2|[Si121Al71O384]–FAU

The thallous ion exchange (TIE) method was used for the first time in an attempt to introduce copper ions into zeolite Y (FAU, Si/Al = 1.69). |Cu _10.9 ⁺ Cu _10.7 ²⁺ Tl _39.2 ⁺ |[Si₁₂₁Al₇₁O₃₈₄]–FAU was prepared by reacting fully dehydrated and fully Tl⁺-exchanged zeolite Y (Tl₇₁–Y) with CuCl₂(g) and its decomposition products CuCl(g) and Cl₂(g) at 673 K under anhydrous conditions. Its structure was determined using single-crystal crystallography with synchrotron X-radiation and was refined in the space group ${Fd}\bar{3}$ m (a = 24.769(1) Å) with all 903 unique data; the final error index, R ₁ = 0.075, was calculated using only the 858 reflections with F _o > 4σ(F _o). About 45 % of the Tl⁺ ions were replaced by 21.6 copper ions per unit cell at the following sites (distances to nearest framework oxygen atoms are given): 10.7 Cu²⁺ at site I′ in the sodalite cavity opposite double 6-rings (Cu²⁺–O = 2.093(9) Å), 3.5 Cu⁺ at site II opposite single 6-rings in the supercage (Cu⁺–O = 2.24(3) Å), and 7.4 Cu⁺ at site III near 12-rings in the supercage (Cu⁺–O = 2.45(7) Å). All Cu⁺ ions are in supercages where they are easily accessible to guest molecules. The remaining ca. 39 Tl⁺ ions per unit cell occupy three distinct positions: 12 are at a second site I′ (Tl⁺–O = 2.571(9) Å), 23 are at a second site II (Tl⁺–O = 2.732(10) Å), and 4 are at site III′ (Tl⁺–O = 2.871(16) Å) near triple 4-rings in the supercages.     

Modeling of Sorption Characteristics of Backfill Materials

ABSTRACT

Sorption data analysis was carried out using the Freundlich, Langmuir, and Modified Freundlich isotherms for the uptake of sodium and potassium in an initial concentration range of 10–100 mg/L on backfill materials, viz., bentonite, vermiculite, and soil samples. The soil samples were collected from a shallow land disposal facility at Kalpakkam. The Freundlich isotherm equation is validated as a preferred general mathematical tool for representing the sorption of K⁺ by all the selected backfill materials. The Modified Freundlich isotherm equation is validated as a preferred mathematical tool for representing the sorption of Na⁺ by the soil samples. Since a negative sorption was observed for the uptake of Na⁺ by commercial clay minerals (vermiculite and bentonite clay in the laboratory experiments), sorption analysis could not be carried out using the above-mentioned isotherm equations. Hill plots of the sorption data suggest that in the region of low saturation (10–40 mg/L), sorption of K⁺ by vermiculite is impeded by interaction among sorption sites whereas sorption by soil and bentonite clay is enhanced by interaction among sorption sites. In the region of higher saturation (60–100 mg/L), sorption of K⁺ by all three backfill materials is enhanced by interaction among sorption sites. The Hill plot of the sorption data for Na⁺ by soil suggests that irrespective of Na⁺ concentration, sorption of Na⁺at one exchange site enhances sorption at other exchange sites.     

Oxidized cellulose: An application in the form of sorption filter materials

Oxidized cellulose (oxycellulose) was very effectively used in the form of filter sheets to remove some metal ions from water and from aqueous solutions. Furthermore, oxycellulose was applied in an ion‐exchange column and in a batch process. The mechanisms of the sorption process inside oxycellulose as well as the kinetics of sorption were studied. A comparison of oxycellulose and other adsorption components such as zeolites and ion‐exchange resins was made. The affinity of oxycellulose to metal ions was determined to be in the following order: Cd²⁺, Zn²⁺ > Ni²⁺ ? Ca²⁺ > Mg²⁺ ? Na⁺. The use of oxycellulose was very effective, especially in the form of sorption filters, because this allowed us to use a simple filtration process. Moreover, the specific loading amount of the filter cake was higher for filtration than for the column process under comparable conditions. Oxycellulose in a glass column behaved similarly to an ion‐exchange resin. It showed approximately constant efficiency until the sorption capacity of the adsorbent was exhausted, and then it suddenly dropped. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies on the use of chromium ferrocyanide gels in the treatment of radioactive wastes

The sorption and distribution of some radioisotopes on chromium ferrocyanide gels under different physical conditions has been investigated. The exchanger shows high selectivity for Tl⁺, Cs⁺, Cd²⁺ and Pb²⁺. A complete elution of Cs⁺, Tl⁺ and Rb⁺ is possible with suitable eluants whereas Pb²⁺ and Cd²⁺ cannot be desorbed. The uptake of monovalent ions is by an ion exchange process unlike the sorption of bivalent ions.     

An Interesting Complex: [Cd(l -trp) (d-trp)] n

A novel coordination polymer [Cd(l-trp) (d-trp)] _n (where l-trp and d-trp are l-tryptophan and d-tryptophan or (S)-2-amino-3-(3-indolyl)propionic acid and (R)-2-amino-3-(3-indolyl)propionic acid) was prepared by a solvent-thermal method and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The compound(monoclinic space group P2(1)/c with a = 19.759(2) Å, b = 5.2496(10) Å, c = 9.7594(16) Å, β = 97.2760(10)°, Z = 2) shows a two-dimensional plane structure. The crystallized coordination polymer has a centrosymmetric space group. Each Cd²⁺ ion coordinates with a pair of racemes, and the complex is a mesomer. Although l-trp was used, both l-trp and d-trp appear in the complex.     

Highly Efficient and Selective Transport of Cu(II) with a Cooperative Carrier Composed of Tetraaza-14-Crown-4 and Oleic Acid through a Bulk Liquid Membrane

Tetraaza-14-crown-4 and oleic acid was successfully applied for transport of Cu(II) in chloroform bulk liquid membrane. The uphill moving of Cu(II) during the liquid membrane transport process has occurred. The main effective variable such as the type of the metal ion acceptor in the receiving phase and its concentration, tetraaza-14-crown-4 and oleic acid concentration in the organic phase on the efficiency of the ion-transport system were examined. By using L-cysteine as a metal ion acceptor in the receiving phase, the maximum amount of copper (II) transported across the liquid membrane was achieved to 96 ± 1.5% after 140 minutes. The selectivity of copper ion transport from the aqueous solutions containing Pb²⁺, Tl⁺, Ag⁺, Co²⁺, Ni²⁺, Mg²⁺, Zn²⁺, Hg²⁺, Cd²⁺ and Ca²⁺ ions were investigated. In the presence of CH₃COONH₄ and Na₄P₂O₇ as suitable masking agents in the source phase, the interfering effects of Pb⁺² and Cd²⁺ were diminished drastically.     

Synthesis and crystal structure of a new oxohalide CdPb<Subscript>2</Subscript>O<Subscript>2</Subscript>Cl<Subscript>2</Subscript>

A new compound, CdPb₂O₂Cl₂, is synthesized by the method of solid-phase reactions. The compound has monoclinic symmetry, space group C2/m, a = 12.392(8) Å, b = 3.8040(14) Å, c = 7.658(5) Å, β = 122.64(5)°, and V = 304.0(3) ų. The structure contains one symmetrically independent position of the Pb²⁺ cation coordinated by three O^2? anions (Pb²⁺-O^2? = 2.29–2.34 Å) and five Cl^? anions (Pb²⁺-Cl^? = 3.35–3.57 Å). The Cd²⁺ cation has a symmetric coordination with the formation of two bonds Cd-O = 2.15 Å and four bonds Cd-Cl = 2.73 Å. The oxygen atom is tetrahedrally coordinated by three Pb²⁺ cations and one Cd²⁺ cation, which leads to the formation of oxo-centered heterometallic OPb₃Cd tetrahedra. The tetrahedra are linked together into chains through common Pb atoms and into layered complexes due to sharing of the equatorial Cd atoms. The chlorine atoms are located above the cavities of the oxo-centered layer.     

Sorption of Pb(II), Cd(II), and Ni(II) From Single- and Multimetal Solutions by Recycled Waste Porous Glass

Selective sorption of lead, cadmium, and nickel ions on recycled waste porous glass beads was investigated. Single-metal equilibrations were carried out in demineralized water and ternary metal equilibrations were carried out in demi- and tap water. Freundlich isotherm gave a good correlation of the experimental data. Maximum metal retention (q_max) in single-ion solutions were 18.66 mg/g_RPWG (0.090 mmol/g_RPWG), 4.83 mg/g_RPWG (0.043 mmol/g_RPWG), 4.00 mg/g_RPWG (0.068 mmol/g_RPWG), respectively, for Pb⁺², Cd⁺², and Ni⁺², and lower figures were in the case of ternary systems: 13.50 mg/g_RPWG(0.065 mmol/g_RPWG), 2.23 (0.020 mmol/g_RPWG), 2.05 mg/g_RPWG(0.034 mmol/g_RPWG), respectively, for Pb⁺², Cd⁺², and Ni⁺², with further drastic reduction in tap water. Metal exhausted beads were used as thermal insulators in cement mortars, minimizing their potential impact in the environment.     

Mechanistic elucidation and evaluation of biosorption of metal ions by grapefruit peel using FTIR spectroscopy,kinetics and isotherms modeling,cations displacement and EDX analysis

BACKGROUND: The performance and mechanism of the biosorptive removal of Ni²⁺ and Zn²⁺ from aqueous solution using grapefruit peel (GFP) as a new biosorbent was investigated by using different experimental approaches, such as potentiometric titration, Fourier transform infrared (FTIR) and energy‐dispersive X‐ray spectroscopy (EDX) analysis, chemical blocking of functional groups and concomitant release of cations (Ca²⁺, Mg²⁺, Na⁺, K⁺) from GFP with metal (Ni²⁺, Zn²⁺) uptake. RESULTS: GFP removed Ni²⁺ and Zn²⁺ rapidly, with 84.73% and 92.46% of the equilibrium sorption being reached in 30 min for Ni²⁺ and Zn²⁺, respectively. The equilibrium process was described well by the Langmuir isotherm model, with maximum sorption capacity of 1.33 and 1.51 meq g^?1 for Ni²⁺ and Zn²⁺, respectively. Release of cations (Ca²⁺, Mg²⁺, Na⁺, K⁺) and protons H⁺ from GFP during uptake of Ni²⁺ and Zn²⁺ and EDX analysis of GFP before and after metal sorption revealed that the main mechanism of sorption was ion exchange. FTIR spectroscopy showed that carboxyl and hydroxyl groups were involved in the sorption of Ni²⁺ and Zn²⁺. Blocking of these groups revealed that carboxylic group was responsible for 78.57% and 73.31% of Ni²⁺ and Zn²⁺ removal, respectively whereas 22.63% and 28.54% was due to the hydroxyl group. The GFP could be regenerated using 0.1 mol L^?1 HCl, with more than 98% metal recovery and reused for five cycles without any significant loss in its initial sorption capacity. CONCLUSIONS: The study suggests that GFP has promising potential for use as an efficient and cost‐effective biosorbent for the removal and recovery of Ni²⁺ and Zn²⁺ from aqueous solution. Copyright © 2009 Society of Chemical Industry     

Rapid and phase pure synthesis of microporous copper silicate (CuSH–1Na) with 12-ring channel system

Phase pure sample of the microporous copper silicate CuSH–1Na has been obtained by simplified hydrothermal method without using additives (H₂O₂ and Na₂HPO₄). Ion exchange of Na⁺ by Cs⁺, Ca²⁺ and Sr²⁺ ions showed that the structure can suffer partial replacement of the charge compensating cations. Ion exchange with Cs⁺ resulted in distinct dehydration while the ion exchange with Sr²⁺ increased the total amount of water. Water content in the Ca-exchanged sample is comparable to the as-synthesized sodium phase. Raman spectroscopy revealed that the divalent cations as Ca²⁺ and Sr²⁺ induce stronger local structural deformations than the monovalent Cs⁺. These structural changes have been also followed by the refined lattice distortions. Magnetic analyses showed that CuSH–1Na presents a very weak ferromagnetic interaction along the Cu²⁺ chains with a nearly vanishing Curie–Weiss temperature. This magnetic coupling is associated with super-super-exchange interactions through Cu–Na–O–Na–Cu paths. Antiferromagnetic coupling, attributed to inter-chains super-super-exchange interactions, competes with the ferromagnetic one and prevails at the lowest temperature.     

Characterization of Adsorptive Capacity and Investigation of Mechanism of Cu2+, Ni2+ and Zn2+ Adsorption on Mango Peel Waste from Constituted Metal Solution and Genuine Electroplating Effluent

Abstract

The present study reports the potential of mango peel waste (MPW) as an adsorbent material to remove Cu²⁺, Ni²⁺, and Zn²⁺ from constituted metal solutions and genuine electroplating industry wastewater. Heavy metal ions were noted to be efficiently removed from the constituted solution with the selectivity order of Cu²⁺ > Ni²⁺ > Zn²⁺. The adsorption process was pH-dependent, while the maximum adsorption was observed to occur at pH 5 to 6. Adsorption was fast as the equilibrium was established within 60 min. Maximum adsorption of the heavy metal ions at equilibrium was 46.09, 39.75, and 28.21 mg g for Cu²⁺, Ni²⁺, and Zn²⁺, respectively. Adsorption data of all the three metals fit well the Langmuir adsorption isotherm model with 0.99 regression coefficient. Release of alkali and alkaline earth metal cations (Na⁺, K⁺, Ca²⁺, Mg²⁺) and protons H⁺ from MPW, during the uptake of Cu²⁺, Ni²⁺, and Zn²⁺, and EDX analysis of MPW, before and after the metal sorption process, revealed that ion exchange was the main mechanism of sorption. FTIR analysis showed that carboxyl and hydroxyl functional groups were involved in the sorption of Cu²⁺, Ni²⁺, and Zn²⁺. MPW was also shown to be highly effective in removing metal ions from the genuine electroplating industry effluent samples as it removed all the three metal ions to the permissible levels of discharge legislated by environment protection agencies. This study indicates that MPW has the potential to effectively remove metal ions from industrial effluents.     

Modification of poly acrylic acid using calix[4]arene derivative for the adsorption of toxic heavy metals

Poly acrylic acid (PAA) was grafted with p‐t‐butyl calix[4]arene diamine (distal cone) (2) to adsorb toxic heavy metal and alkali metal cations. The grafting method includes the amidation reaction of PAA with calixarene diamine derivative 2 which was carried out in N,N‐dimethylformamide (DMF) and N–methyl‐2‐pyrrolidone (NMP) as solvents. The modified PAAs (PAA‐C1 and PAA‐C2) were characterized by FTIR, ¹H‐NMR, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). PAA‐C1 and PAA‐C2 were used to evaluate the sorption properties of some toxic heavy metal cations (Co²⁺, Cu²⁺, Cd²⁺, Hg²⁺), alkali metal cations (Na⁺, K⁺, Cs⁺), and Ag⁺. Results showed that the modified PAAs were good sorbents for heavy metal and alkali metal cations. The main goal of this project is to design hydrophobically modified PAA that is suitable for ion selective membranes and chemical sensor devices for adsorption of toxic heavy metals. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of new optically active polymers carrying calix[4]arene and amino acid units in the main chain and their binding properties towards toxic heavy metals

BACKGROUND: A series of novel optically active polymers containing upper rim calix[4]arene was prepared from the polycondensation reaction of calix diamine derivative 2 with two optically active diacid chlorides. RESULTS: The optically active compounds were prepared from the reaction of a pyromellitic dianhydride with two chiral amino acids. The optically active polymers were obtained in a yield of 80–86% and had an inherent viscosity of 0.20–0.26 dL g^?1. The polymers were characterized using Fourier transform infrared and ¹H NMR spectroscopy and elemental analysis. Studies of the complexation of the polymers towards some alkali metal and toxic transition metal cations were performed using solid–liquid sorption procedures and comparisons made with the starting monomer. CONCLUSION: It is evident from the complexation studies that the polymers investigated are good polymeric ionophores for alkali metal cations like Na⁺ and K⁺, for Ag⁺ and for toxic heavy metal cations such as Cu²⁺, Co²⁺, Cd²⁺ and Hg²⁺. These polymers are good candidates for use in chiral stationary phases for separation of enantiomers in ionic media, as well for removing metal ions. Copyright © 2009 Society of Chemical Industry     

Contribution a l'etude des complexes du cation cadmium (II) avec l'acide laćtique et l'acide malonique en milieu Na+(ClO−4)3M A 25°C

The potentiometric study of neutralisation at 25°C, in Na⁺ (ClO^?₄)3M medium, with NaOH as titrant, of solutions: Cd²⁺ cation-lactic acid (between neutralisation rate values 0 to 1); and of Cd²⁺ cation-malonic acid (between neutralisation rate values 1–2), allows consideration of the formation of mononuclear complexes with lactic acid, and mononuclear and polynuclear complexes with malonic acid.The interpretation of experimental data ph = f(x)_R induces one to suppose the existence of the following species: lactic acid: Cd(Lact)⁺, Cd(Lact)₂; malonic acid; Cd(Mal); Cd(Mal)^2?₂; Cd(Mal)^4?₃; Cd₂(Mal)₂; Cd₂(Mal)^2?₃.The constants of formation of those complexes have been determined by non-linear regression.