Adsorption of metal cations on wool carbonising waste. Part 1. Adsorption isotherms

The adsorption of various metal ions (Hg²⁺, Ag⁺, Ni²⁺, Cr³⁺, Al³⁺, Zn²⁺ and Pb²⁺) on wool carbonising waste has been investigated to assess its possible use as an adsorbent in water pollution control. Isotherms show that few metal ions (Hg²⁺, Ag⁺ and Ni²⁺) are adsorbed satisfactorily by this material. Moreover, the adsorption capacity of the plant material within the carbonising waste is higher than that of the keratin fraction. Equations fitting the experimental data can be used for the design of processing units.     

Voltammetric characterization of selective potassium ion transfer across micro-water/1,2-dichloroethane interface facilitated by a novel calix[4]arene derivative

In this study, transfer reactions of alkali and alkaline-earth metal ions across a micro-water/1,2-dichloroethane (1,2-DCE) interface facilitated by a novel calix[4]arene derivative, 5,11,17,23-tetra-tert-butyl-25,27-bis(2′amino-methylpyridine)-26,28-dihydroxy calix[4]arene (APHC4), were investigated by cyclic and differential pulse voltammetry techniques. Well-defined voltammetric behavior was obtained only for K⁺ ion among the used metal ions. The electrochemical data were used to determine the stoichiometry and the appropriate association constant of the occurring complex between K⁺ ion and APHC4. The obtained steady-state voltammograms indicated that the facilitated transfer process occurs with a TIC/TID mechanism according to 1:1 stoichiometry. The logarithm of the association constant () of K(APHC4)⁺ complex in the DCE phase was calculated to be 6.32. Also, the availability of the facilitated transfer for the design of an amperometric screening sensor for K⁺ ion was evaluated in the range of 50–500 μmol dm⁻³.     

Chromogenic sensing of Cu(II) by imino linked thiacalix[4]arene in mixed aqueous environment

Thiacalix[4]arene based imino receptors 4–5 carrying azophenol appendage have been synthesized and studied for their binding abilities towards different metal ions (Li⁺, Na⁺, K⁺, Cd²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Ag⁺, Pb²⁺ and Hg²⁺). Receptor 4 showed selective chromogenic sensing for Cu²⁺ ions in mixed aqueous conditions (THF:H₂O, 9:1 v/v).     

Hg detection by aniline-based conjugated copolymers with high selectivity

Conjugated polymers (P1, P1L and P2-P5) constructed by alkynyl-substituted aniline and substituted arene analogs could be synthesized through Pd-catalyzed Sonogashira coupling. The responsive optical properties of poly(2-ethynyl aniline) (P1 and P1L for different molecular weights, P1L with longer chains on average) toward various metal ions (including Ni²⁺, Ag⁺, Cu²⁺, Zn²⁺, Fe³⁺, Fe²⁺, Mn²⁺, Na⁺, Ca²⁺, Pb²⁺, K⁺, Cr³⁺, Al³⁺, Cd²⁺, Pt²⁺, Au³⁺ and Tl³⁺) were investigated. Hg²⁺ exhibited the most pronounced fluorescence response of both P1 and P1L without interference from those coexistent ions due to aniline in the polymer backbone as the metal binding ligand, while other metal ions does not cause obvious change of fluorescence. Compared with P1, P1L exhibits better sensitivity toward Hg²⁺. Introducing pyridyl, thienyl or phenyl groups into the polymer backbone would weaken the quenching responses to Hg²⁺ compared with P1. The results indicated P1 and P1L could be used as a selective fluorescence sensor toward Hg²⁺.     

Cu2+ Selective Chromogenic Behavior of Calix[4]arene Derivative

This study involves the copper selective chromogenic response of 5, 11, 17, 23-Tetrakis (N-pyrrolidinomethyl)-25, 26, 27, 28-tetrahydroxycalix[4]arene based mannich base (3). Complexation ability of (3) was explored by examining the effect of a series of various metal ions, such as Li⁺, Na⁺, K⁺, Ag⁺, Ba²⁺, Ca²⁺, Mn²⁺, Mg²⁺, Sr²⁺, Ni²⁺, Cd²⁺, Co²⁺, Cu²⁺, Hg²⁺, Pb²⁺, Zn²⁺, Fe²⁺, Fe³⁺, and Al³⁺, by using UV-visible spectroscopy. Ligand (3) exhibited pronounced selectivity toward Cu²⁺ even in the presence of various co-existing ions. The stoichiometric analysis, i.e., Job's plot revealed that (3) form 1:1 complex with Cu²⁺ ion in DMF-H₂O system. The complexation phenomenon was confirmed by FT-IR spectroscopy that favors the selective nature of (3) with Cu²⁺.     

Rhodamine-based fluorescent sensor for mercury in buffer solution and living cells

A novel fluorescent sensor based on thiooxorhodamine B has been prepared to detect Hg²⁺ in aqueous buffer solution. It demonstrates high selectivity for sensing Hg²⁺ with about 383-fold enhancement in fluorescence emission intensity and micromolar sensitivity (K_d = 7.5 × 10⁻⁶ mol L⁻¹) in comparison with alkali and alkaline earth metal ions (K⁺, Na⁺, Mg²⁺, Ca²⁺) and other transition metal ions (Mn²⁺, Ni²⁺, Co²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ag⁺, Pb²⁺, Cr³⁺, Fe³⁺). Meanwhile the distinct color changes and rapid switch-on fluorescence also provide ‘naked eyes’ detection for Hg²⁺ over a broad pH range. Moreover, such sensor is cell-permeable and can visualize the changes of intracellular mercury ions in living cells using fluorescence microscopy.     

Rhodamine-based fluorescent sensor for mercury in buffer solution and living cells

A novel fluorescent sensor based on thiooxorhodamine B has been prepared to detect Hg²⁺ in aqueous buffer solution. It demonstrates high selectivity for sensing Hg²⁺ with about 383-fold enhancement in fluorescence emission intensity and micromolar sensitivity (K_d = 7.5 × 10⁻⁶ mol L⁻¹) in comparison with alkali and alkaline earth metal ions (K⁺, Na⁺, Mg²⁺, Ca²⁺) and other transition metal ions (Mn²⁺, Ni²⁺, Co²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ag⁺, Pb²⁺, Cr³⁺, Fe³⁺). Meanwhile the distinct color changes and rapid switch-on fluorescence also provide ‘naked eyes’ detection for Hg²⁺ over a broad pH range. Moreover, such sensor is cell-permeable and can visualize the changes of intracellular mercury ions in living cells using fluorescence microscopy.     

A new Cu-selective self-assembled fluorescent chemosensor based on thiacalix[4]arene

A new ON–OFF fluorescent chemosensor for Cu²⁺ ions was prepared through self-assembly inside Triton X-100 micelles of p-tert-butylthiacalix[4]arene (TCA) and perylene in water solution. This thiacalix[4]arene-based self-assembled fluorescent chemosensor could realize the direct sensing of Cu²⁺ ions in aqueous solution. Addition of Cu²⁺ ions could result in a quenching of the fluorescence emission of perylene inside the micelles, which is ascribed to intramicellar complex-fluorophore electron-transfer or energy-transfer effects induced by the complexation of TCA with the Cu²⁺ ions. Cu²⁺ ions can be detected selectively in the presence of other metal ions (Zn²⁺, Pb²⁺, Cd²⁺, Mn²⁺, Ni²⁺, Al³⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺) and its concentration in the submicromolar range can be almost linearly determined according to the fluorescence quenching.     

Grafting of tea waste with polyacrylic acid and its potential applications

The indigenous materials such as tea waste were exploited as antimicrobial adsorbent for removing heavy metal ions. It was well known that tea waste was characterized with biodegradability and environmental-friendly product. Grafting copolymerization of acrylic acid onto tea waste was carried out using gamma radiation. The effects of solvent, dose and feeding concentration of acrylic acid have been investigated to achieve the optimum conditions. Grating (%) ranged from 30 to 70 for DMSO and H₂O, respectively. The grafted tea waste was characterized by Fourier transform infrared (FTIR) spectroscopy, swelling study, scanning electron microscopy (SEM) and energy dispersive spectrometry X-rays (EDS). The grafted samples were used in waste water treatment to remove heavy metal ions (Cr³⁺, Pb²⁺ and Hg²⁺). The highest adsorption capacity was 35 and 200 mg/g of Hg⁺² ions for ungrafted and grafted samples, respectively. The results showed that the selectivity among these metal ions is different onto tea waste-graft-polyacrylic acid. The grafted tea waste samples, which complexed with Cr³⁺, Pb²⁺ and Hg²⁺ ions, were found to have antimicrobial features. Therefore, they could be used as adsorbent in removing heavy metal ions with antimicrobial features as well.

     

Synthesis of SPR Nanosensor using Gold Nanoparticles and its Application to Copper (II) Determination

This research describes a colorimetric assay for Cu (II) ions that is highly selective over other metal ions. It is based on the measurement of changes in the surface plasmon resonance absorbance (at 525 nm) of gold nanoparticles (Au NPs) modified with 1,7-diaza-15-crown-5 (Crown-Au NPs). The unique structure of crown ethers and presence of heteroatoms enable the crown-Au NPs to recognize very low concentrations of Cu (II) ions. After aggregation, the surface plasmon absorption band has a red shift so that the nanoparticle solution shows a violet color. The TEM images data show that this color change is a result of crown-Au NPs aggregation upon addition of Cu (II), In contrast, other metal ions Al³⁺, Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Ag⁺, Fe²⁺, Fe³⁺, Hg²⁺, K⁺, Mg²⁺, Mn²⁺, Na⁺, Ni²⁺, Pb²⁺, and Zn²⁺ do not aggregate. The recognition mechanism is attributed to the formation of a sandwich (2+1) between the Cu (II) ion and two diaza-15-crown-5 moieties that are attached to separate nanoparticles. This simple and fast method can be used to determine the Cu (II) ions with a detection limit as low as 200 nM.     

C,N‐Pyridylpyrazole‐Based Ligands: Synthesis and Preliminary Use in Metal Ion Extraction

Abstract

The synthesis of new N‐donor pyridylpyrazole ligands with a functionalized arm is described. The complexation capabilities of these compounds towards bivalent metal ions (Hg²⁺, Cd²⁺, Pb²⁺, Cu²⁺, and Zn²⁺) and alkali metal ions (K⁺, Na⁺, and Li⁺) were investigated using the liquid‐liquid extraction process. The percentage limits of extraction were determined by atomic absorption measurements.     

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.     

Synthesis of Starch-Stabilized Ag Nanoparticles and Hg2+ Recognition in Aqueous Media

The starch-stabilized Ag nanoparticles were successfully synthesized via a reduction approach and characterized with SPR UV/Vis spectroscopy, TEM, and HRTEM. By utilizing the redox reaction between Ag nanoparticles and Hg²⁺, and the resulted decrease in UV/Vis signal, we develop a colorimetric method for detection of Hg²⁺ ion. A linear relationship stands between the absorbance intensity of the Ag nanoparticles and the concentration of Hg²⁺ ion over the range from 10 ppb to 1 ppm at the absorption of 390 nm. The detection limit for Hg²⁺ ions in homogeneous aqueous solutions is estimated to be ~5 ppb. This system shows excellent selectivity for Hg²⁺ over other metal ions including Na⁺, K⁺, Ba²⁺, Mg²⁺, Ca²⁺, Fe³⁺, and Cd²⁺. The results shown herein have potential implications in the development of new colorimetric sensors for easy and selective detection and monitoring of mercuric ions in aqueous solutions.     

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,characterization, and metal ions adsorption properties of chitosan–calixarenes (I)

Calixarene‐modified chitosans (CTS–CA‐I and CTS–CA‐II) were first synthesized by the reaction of chitosan (CTS‐NH₂) with 1,3‐bis‐chloroethoxyethoxy‐2,4‐dihydroxy‐p‐tert‐butylcalix[4]arene (CA‐I) or its benzoyl derivative (CA‐II). Their structures were characterized by infrared and X‐ray diffraction spectroscopy and scanning electron microscopy (SEM). The adsorption of Ni²⁺, Cd²⁺, Cu²⁺, Pd²⁺, Ag⁺, and Hg²⁺ by CTS–CA‐I and CTS–CA‐II was studied and the thermodynamic parameter of two calixarene‐modified chitosans toward Hg²⁺ was deduced. The adsorption properties of CTS–CA‐I and CTS–CA‐II were greatly varied compared with that CTS‐NH₂, especially with the adsorption capacity toward Ag⁺ and Hg²⁺, because of the presence of the calixarene moiety. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1139–1144, 2003     

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.     

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     

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.     

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.     

Physicochemical investigation of radiation‐grafted poly(acrylic acid)‐graft‐poly(tetrafluoroethylene–ethylene) copolymer membranes and their use in metal recovery from aqueous solution

ET‐g‐PAAc membranes were obtained by radiation grafting of acrylic acid onto poly(tetrafluoroethylene–ethylene) copolymer films using a mutual technique. The ion selectivity of the grafted membranes was determined toward K⁺, Ag⁺, Hg²⁺, Co²⁺, and Cu²⁺ in a mixed aqueous solution. The ion‐exchange capacity of the grafted membranes was measured by back titration and atomic absorption spectroscopy. The Hg²⁺ ion content of the membrane was more than that of either the K⁺ or Ag⁺ ions. The presence of metal ions in the membranes was studied by infrared and energy‐dispersive spectroscopy measurements. Scanning electron microscopy of the grafted and metal‐treated grafted membranes showed modification of the morphology of the surface due to the adsorption of K⁺ and Ag⁺ ions. No change was observed for the surface of the membrane that was treated with Hg²⁺ ions. The thermal stability of different membranes was improved more with Ag⁺ and Hg²⁺ ions than with K⁺ ions. It was found that the modified grafted membranes possessed good hydrophilicity, which may make them promising candidates for practical applications, such as for cation‐exchange membranes in the recovery of metals from an aqueous solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2692–2698, 2002