Mixed ligand ion buffers for calibrating ion-selective electrodes at trace levels

1990 ◽  
Vol 333 (1628) ◽  
pp. 163-163 ◽  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Concentration Ratio ◽  
Ph Value ◽  
Mixed Ligand ◽  
Ligand Concentration ◽  
Ion Selective Electrodes ◽  
Equivalence Point ◽  
Metal Ligand ◽  
Standard Solutions

The calibration of cation-selective electrodes has been facilitated by the use of ion buffers. Hitherto, calibration was made using solutions containing the metal ion and an appropriate complexing ligand, such as EDTA in an appropriate concentration ratio, or by changing the pH value of a solution with fixed metal-ligand concentration. To cover a wide calibration range, say from 10 -7 to 10 -3 m [Ca 2+ ], standard solutions involving at least two different ligands had to be prepared. These approaches were both cumbersome and lacked precision in the unbuffered region near the equivalence point of titration of ligand with metal ions.

scholarly journals Effective removal of heavy metal ions from aqueous solutions using a new chelating resin poly [2,5-(1,3,4-thiadiazole)-benzalimine]: kinetic and thermodynamic study

2015 ◽  
Vol 6 (2) ◽  
pp. 310-324 ◽  
Author(s):  
Selvaraj Dinesh Kirupha ◽  
Selvaraj Kalaivani ◽  
Thangaraj Vidhyadevi ◽  
Periyaraman Premkumar ◽  
Palanithamy Baskaralingam ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ph Value ◽  
Thermo Gravimetric Analysis ◽  
Kinetic Studies ◽  
Ion Concentration ◽  
Chelating Resin ◽  
Gravimetric Analysis ◽  
Equilibrium Data ◽  
Experimental Values

A novel poly [2,5-(1,3,4-thiadiazole)-benzalimine] abbreviated as TDPI adsorbent was synthesized using simple polycondensation technique. The synthetic route involves the preparation of 2,5-diamino-1,3,4-thiadiazole from 2,5-dithiourea and subsequent condensation with terephthalaldehyde. The resin was chemically characterized using Fourier transform infrared (FT-IR), 1H-NMR, and 13C-NMR spectroscopic analysis. Surface morphology and thermal stability were analyzed using scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The effect of the pH value of solution, contact time, adsorbent dose, and initial metal ion concentration were investigated by batch equilibrium adsorption experiments. Kinetic studies show that the adsorption of metal ions onto the resin proceeds according to the pseudo-second-order model and the equilibrium data were best interpreted by the Redlich–Peterson isotherm. The experimental values of the adsorption capacities of Pb2+, Cu2+, Ni2+, and Cd2+ on to TDPI could reach up to 437.2, 491.6, 493.7, and 481.9 mg.g−1 respectively. The exothermic nature of the process, the affinity of the adsorbent towards the metal ions and the feasibility of the process are explained in the thermodynamic parameters. The resin stability and re-usability studies suggest that the resin is chemically stable (0.3 N HCl and H2SO4) and could be regenerated without any serious decline in performance.

Metal ion – biomolecule interactions. Part 16. C(2)-H isotopic exchange in Co(III)-coordinated imidazoles

1995 ◽  
Vol 73 (6) ◽  
pp. 772-780 ◽  
Author(s):  
Erwin Buncel ◽  
Fan Yang ◽  
Robert Y. Moir ◽  
Ikenna Onyido
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Hydrogen Exchange ◽  
Isotopic Exchange ◽  
Negative Charge ◽  
Ligand Complex ◽  
Transition State Stabilization ◽  
Anionic Species ◽  
Metal Ligand ◽  
Ligand Bond

Transition-metal-bound imidazoles are suitable models for evaluating the roles of metal ions in biomolecules having the imidazole moiety and similar heterocyclic residues as part of their structure. Such studies provide useful insights into metal–biomolecule interactions in biological systems, especially when the lability of the metal–ligand bond is substantially reduced, such that the identity of the metal–ligand complex is preserved during the course of the reaction under investigation. The present paper reports on a kinetic study of tritium exchange from the C(2) position of the imidazole moiety in the substitution-inert complex cations [Co(NH3)5[2-3H]-imidazole]3+ (1) and [Co(NH3)5-1-methyl-[2-3H]-imidazole]3+ (2). Rate–pH profiles have been determined in aqueous solution at 60 °C. Both substrates are believed to react through rate-determining attack of hydroxide ion (kM+ pathway) at C(2)-T. Dissection of the kinetic data reveals an additional pathway for 1 consequent upon deprotonation of its pyrrole-like N-H(T) to yield 3, which is then attacked by hydroxide at C(2) (kM pathway). The ratio kM+/kM = 103 that is obtained is in accord with the expected reduced reactivity of 3. Comparison of the present data with those reported for a variety of heterocyclic substrates shows that the order of reactivity, protonated [Formula: see text] metal ion coordinated [Formula: see text] neutral form of substrates, prevails. The superiority of the proton over metal ions in catalyzing isotopic hydrogen exchange is attributed to its larger ground state acidifying effect coupled with the greater transition state stabilization it affords, relative to metal ions. The exchange reaction of 3 via the kM pathway is the first example of a reactive anionic species in which the negative charge is located α to the exchanging C-H. Keywords: tritium exchange, cobalt (III)-coordinated imidazoles.

scholarly journals Column Extraction and Separation of Some Metal Ions by Diethylenetriamine Polysiloxane Immobilized Ligand System

2008 ◽  
Vol 5 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Nizam M. El-Ashgar
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ph Value ◽  
Good Separation ◽  
Extraction And Separation ◽  
Ph Values ◽  
Ligand System ◽  
Chromatographic Parameters ◽  
Column Extraction ◽  
Optimum Separation

An extraction chromatographic solid porous polysiloxane functionalized by chelating diethylenetriamine ligand of the general formula P-(CH2)3-NH(CH2)2NH(CH2)2NH2, (Where P represents [Si-O]nsiloxane network) has been evaluated for the separation of Co(II), Ni(II) and Cu(II) from aqueous solutions. The chromatographic parameters of the separation method have been optimized. The ligand system retained Co(II), Cu(II) and Zn(II) effectively when used as a metal ion extractant by controlling the pH value. The ligand system also shows a good separation of a mixture of metal ions Co(II), Ni(II) and Cu(II) when used as chromatographic stationary phase. The optimum separation pH values were 4.5, 4 for Co(II) and Ni(II) respectively, while a solution of 0.1 M HNO3was used to elute Cu(II). Metal ions were also preconcentrated at pH 5.5. The chemisorbed metal ions were regenerated from the solid extractant using 0.5 M HCl.

Removal of Pb(II), Zn(II), Sn(II) and Cu(II) Ions from Aqueous Solutions by Linear Alternating Poly(4,4'-biphenol oxalate) Oligomer

2020 ◽  
Vol 15 (2) ◽  
pp. 73-85
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Metal Ion ◽  
Ph Value ◽  
Equilibrium Concentration ◽  
Ion Uptake ◽  
Uptake Capacity ◽  
Concentration Data ◽  
Hno3 Solution ◽  
Metal Ion Uptake

Poly(4,4′-biphenol oxalate) oligomer was synthesized and characterized by FT-IR, elemental analysis XRD and thermal analysis. The capability of the oligomer to take away Pb(II), Zn(II), Sn(II) and Cu(II) metal ions from aqueous solutions was considered by the known batch and column techniques in terms of concentration, pH value, contact time and temperature. The results indicated that a high initial rate of metal-ion uptake by the oligomer was observed throughout the first 30 minutes, which enlarged slightly amid rising the pH value and then reached its greatest value at pH=5.00 for Pb(II) and Zn(II), pH=4.00 for Cu(II) and pH=6.00 for Sn(II). The oligomer exhibited a high metal-ion uptake capacity to Pb(II) and Zn(II), but a little metal-ion uptake capacity to Cu(II) and Sn(II). Linearized forms of the Langmuir, Freundlich and Dubinin–Radushkevich adsorption isotherms were used to investigate the experimental equilibrium concentration data of Pb(II), Zn(II), Cu(II) and Sn(II). ΔG values demonstrated that the adsorption process of these metal ions on the oligomer is favored while the ΔH values indicated that this process is endothermic. On the other hand, the entropy of the process is positive. In addition to batch experiments, column experiments were performed, where the metal ions were efficiently recovered by treatment of the metal-loaded oligomer with 1.0 M HNO3, 1.0 M HCl and 0.5 M EDTA. The best results were obtained with 1.0 M HNO3 solution.

scholarly journals Adsorption properties of a nanostructured hybrid material containing aluminium towards some metal ions

2011 ◽  
Vol 9 (5) ◽  
pp. 932-940 ◽  
Author(s):  
Albena Detcheva ◽  
Paunka Vassileva ◽  
Ralitsa Georgieva ◽  
Dimitrinka Voykova ◽  
Tsvetelina Gerganova ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Hybrid Material ◽  
Metal Ion ◽  
Ph Value ◽  
Sol Gel ◽  
Transition Metal Ions ◽  
Adsorption Properties ◽  
Adsorption Of Nitrogen ◽  
Pseudo Second Order

AbstractIn the present work the adsorption of some transition metal ions from aqueous solutions on a silica-based nanostructured hybrid material modified by aluminium was investigated. The novel organic-inorganic material was synthesized via a sol-gel method through hydrolysis and co-condensation reactions. Its structure was characterized by means of SEM, XRD and FTIR. Based on the data obtained the most probable cross-linking mechanism for the derived xerogel was proposed. The characterization of its texture parameters was carried out by low-temperature adsorption of nitrogen. The adsorption properties of this material with respect to Cu(II), Cr(III) and Pb(II) ions from single-component aqueous solutions and multi-component aqueous solutions containing also Cd(II) and Fe(III) were evaluated. The effect of contact time, acidity of initial solutions and metal ion concentrations was investigated using the batch method. Pseudo-first order, pseudo-second order and intraparticle diffusion models were used to analyze kinetic data. In all cases the adsorption was significantly affected by the pH value. Equilibrium modelling data were fitted to linear Langmuir, Freundlich and Dubinin-Radushkevich models. Best fit was observed for Langmuir model, which showed determination coefficients greater than 0.992 for all ions studied. The maximum adsorption capacities for single- and multi-component adsorption were calculated.

scholarly journals Production of activated carbon from poultry feathers for waste water treatment

2019 ◽  
Vol 80 (8) ◽  
pp. 1407-1412 ◽  
Author(s):  
Rue Chiramba ◽  
Gratitude Charis ◽  
Nonhlanhla Fungura ◽  
Gwiranai Danha ◽  
Tirivaviri Mamvura
Keyword(s):  
Waste Water ◽  
Heavy Metal ◽  
Activated Carbon ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Ph Value ◽  
Waste Water Treatment ◽  
Limiting Factors ◽  
Poultry Feathers

Abstract Contamination of water bodies by heavy metal ions is a challenge many developing nations like Zimbabwe face, with negative environmental and socio-economic repercussions. Treating affected bodies usually requires a costly consignment of chemicals and activated carbon. This research investigates the possible use of an abundant waste resource – poultry feathers – to make activated carbon for heavy metal ion removal. Poultry consumption in this nation generates more than five million tonnes of feathers a year, with very few uses of this by-product. This research was carried out to evaluate the effectiveness of activated carbon synthesized from poultry feathers with sodium hydroxide as the activating agent. It was tested for removing heavy metal ions from waste water at Lake Chivero and the experimental work done showed that it had a removal efficiency as high as 97%, with a high affinity for lead ions as compared with chromium ions. Upon characterization, the activated carbon showed an iodine number of 520 mg and it worked best at a pH value of 8. The efficiency removal also increased with increasing adsorbent concentration as well as contact time up to a period where these factors ceased to be the limiting factors of the reaction.

Study on the Adsorption of Mixed Cd(II) and Pb(II) Ions by N,O-Carboxymethyl-Chitosan

2011 ◽  
Vol 236-238 ◽  
pp. 2523-2528
Author(s):  
Shan Shan Cheng ◽  
Chao Hua Zhang ◽  
Xi Hong Yang ◽  
Wan Cui Xie
Keyword(s):  
Metal Ions ◽  
Adsorption Capacity ◽  
Metal Ion ◽  
Ph Value ◽  
Carboxymethyl Chitosan ◽  
Effect Of Temperature ◽  
Mixed Solution ◽  
Isotherm Equation ◽  
Mixed Aqueous Solution ◽  
Langmuir Isotherm Equation

TheN,O-carboxymethyl-chitosan (N,O-CMC) was used to investigate the adsorptions of two metals of Cd(Ⅱ) and Pb(Ⅱ) ions in an mixed aqueous solution. The effects on adsorption capacities such as pH value, temperature, adsorbent dose and initial metal ion concentrations were investigated, and the dialysis method was applied to separate the materials after adsorption. The results revealed that the better adsorption ofN,O-CMC for Cd(Ⅱ) and Pb(Ⅱ) ions at the pH 7-8; the effect of temperature on the adsorption was not significant; the absorption of Cd(Ⅱ) and Pb(Ⅱ) ions was enhanced with the increase ofN,O-CMC amount; the adsorption capacity increasesed with the addition of the concentration of initial metal ions in the aqueous phase. The adsorption of Pb(Ⅱ) ion in Cd-Pb mixed solution on theN,O-CMC was well followed as the Langmuir isotherm equation under the concentration range studied, and Cd(Ⅱ) ion was corresponding to Langmuir adsorption equation in 100-200 mg/L and 200-500 mg/L, respectively. Conclusion:N,O-CMC was suitable for adsorbent to removal Cd(Ⅱ) and Pb(Ⅱ) ions, but it can selectively adsorption ions from the mixed solution, the adsorption capacity (Qm) for two metal ions was as follows: Pb(Ⅱ) > Cd(Ⅱ).

scholarly journals Using amine-functionalized magnetite hollow nanospheres (AMHNs) as adsorbents for heavy metal ions

2017 ◽  
Vol 76 (2) ◽  
pp. 452-458 ◽  
Author(s):  
Sen Lin ◽  
Lili Liu ◽  
Yong Yang ◽  
Wei Zhang ◽  
Meng Xu ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Ph Value ◽  
Hollow Nanospheres ◽  
One Pot ◽  
Amine Functionalized ◽  
Physicochemical Features ◽  
Kinetics And Isotherms

In this paper, the amine-functionalized magnetite hollow nanospheres (AMHNs), prepared through a facile one-pot synthesis, were used as heavy metal ion adsorbents, whose morphology and physicochemical features were exploring by transmission electron microscopy, vibrating sample magnetometer, X-ray diffraction and Fourier-transform infrared analyses. Its adsorption performances for Pb2+, Cu2+, Zn2+, Ni2+ and Cd2+ were studied in detail. The adsorption increased with the increase of initial pH value of the solution and could be obviously affected by ionic strength. Also, the adsorption kinetics and isotherms were studied. The adsorption processes for Pb2+, Cu2+, Zn2+, Ni2+ and Cd2+ could all reach equilibrium in 60 min and be described well by the Langmuir thermodynamics model. The saturated adsorption capacities for Pb2+, Cu2+, Zn2+, Ni2+ and Cd2+ were 0.66, 0.47, 0.45, 0.38 and 0.26 mmol/g, respectively. In addition, the competitive adsorption showed the AMHNs had higher affinity to Pb2+ than to other heavy metal ions.

scholarly journals Heavy Metal Ion Adsorption Properties of Methacrylamidocysteine-Containing Porous Poly(Hydroxyethyl Methacrylate) Chelating Beads

2002 ◽  
Vol 20 (7) ◽  
pp. 607-617 ◽  
Author(s):  
Adil Denizli ◽  
Bora Garipcan ◽  
Sibel Emir ◽  
Süleyman Patir ◽  
Ridvan Say
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Metal Removal ◽  
Ph Value ◽  
Heavy Metal Removal ◽  
Ion Concentration ◽  
Heavy Metal Ion ◽  
Adsorption Capacities

Details of the adsorption performance of poly(2-hydroxyethylmethacrylate–methacrylamidocysteine) [p(HEMA–MAC)] beads towards the removal of heavy metal ions from aqueous solution were studied. The metal-complexing ligand and/or co-monomer MAC was newly synthesized from methylacrylochloride and cysteine. Spherical beads of average size 150–200 mm were obtained by the radical suspension polymerization of MAC and HEMA conducted in an aqueous dispersion. The p(HEMA–MAC) beads obtained had a specific surface area of 18.9 m2/g. p(HEMA–MAC) beads were characterized by swelling studies, FT-IR spectroscopy and elemental analysis. Such beads with a swelling ratio of 72%, and containing 3.9 mmol MAC/g, were used for heavy metal removal studies. The adsorption capacities of the beads for selected metal ions, i.e. CdII, AsIII, CrIII, HgII and PbII, were investigated in aqueous media containing different amounts of these ions (10–750 mg/l) and at different pH values (3.0–7.0). The adsorption rate was fast in all cases. The maximum adsorption capacities of the p(HEMA–MAC) beads were 1058.2 mg/g for CdII, 123.4 mg/g for AsIII, 199.6 mg/g for CrIII, 639.1 mg/g for PbII and 1018.6 mg/g for HgII. On a molar basis, the following affinity order was observed: CdII > HgII > CrIII > PbII >AsIII. The adsorption capacity of the MAC-incorporated beads was affected significantly by the pH value of the aqueous medium. The adsorption of heavy metal ions from artificial wastewater was also studied. In this case, the adsorption capacities were 52.2 mg/g for CdII, 23.1 mg/g for CrIII, 83.4 mg/g for HgII, 62.6 mg/g for PbII and 11.1 mg/g for AsIII at an initial metal ion concentration of 0.5 mmol/l. The chelating beads could be regenerated easily with a higher effectiveness by 0.1 M HNO3. These features make p(HEMA–MAC) beads potential candidates for heavy metal ion removal at high capacity.

Structural and spectroscopic studies of transition metal nitrite complexes. II. Crystal structures of cis-Bis(ethane-1,2-diamine)(nitrito-O,O')zinc(II) nitrite and trans-Bis[N,N-dimethyl(ethane-1,2-diamine)]dinitritozinc(II)

1981 ◽  
Vol 34 (10) ◽  
pp. 2061 ◽  
Author(s):  
AJ Finney ◽  
MA Hitchman ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Crystal Structures ◽  
Coordination Polyhedron ◽  
Metal Ion ◽  
Spectroscopic Studies ◽  
Bond Lengths ◽  
Coordination Sites ◽  
Metal Ligand ◽  
Ligand Bond

The crystal structures of the complexes cis-bis(ethane-1,2-diamine)(nitrito-O,O')zinc(II) nitrite and trans-bis[N,N-dimethyl(ethane-l,2-diamine)]dinitritozinc(II) are described. The former compound contains one chelating nitrite, the second group being present as a counter ion. In this complex the coordination polyhedron about the metal ion may be described either as a distorted trigonal bi-pyramid or an octahedron, depending upon whether the chelated nitrite is considered to occupy one or two coordination sites. The second compound is a trans nitrito complex, having an octahedral ligand geometry, though with three markedly different metal-ligand bond lengths. The structures of the complexes are compared with those of analogous nickel(II) nitrite complexes, and the differences are discussed in terms of the electron configurations of the two metal ions.

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