The effect of pH and ligands on the sorption of heavy metal ions by cellulose

1978 ◽  
Vol 31 (7) ◽  
pp. 1501 ◽  
Author(s):  
H Farrah ◽  
WF Pickering
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ethylenediaminetetraacetic Acid ◽  
Zinc Ions ◽  
Natural Systems ◽  
Ph Values ◽  
Hydrated Ions ◽  
Pka Value ◽  
Anionic Complexes ◽  
Copper Lead

The adsorption of copper, lead, cadmium and zinc ions by cellulose suspensions has been examined at pH values ranging from 3.5 to 11. The chemical form of the metal ions has been changed by adding ligands such as oxalic acid, citric acid, tartaric acid, ethylenediaminetetraacetic acid, ethylene- diamine, glycine, cysteine and α,α'-bipyridyl. Stable anionic complexes were not sorbed by the cellulose, and at a given pH cationic complexes were sorbed less than hydrated ions. The presence of excess ligand generally served to mask the precipitation of the metal- hydroxy species which can occur in the pH 6-7 region. ��� The amount of metal cation sorbed increased with pH. This has been attributed to increased ionization of acid functional groups having a pKa value of around 4.4. ��� The implication of the results, in respect to aqueous metal ion levels in natural systems, has been considered.

scholarly journals Multiple α-mannosidase activities in mammalian tissues as shown by metal-ion activation

1977 ◽  
Vol 163 (3) ◽  
pp. 557-564 ◽  
Author(s):  
S M Snaith
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Active Enzyme ◽  
Thiol Groups ◽  
Ion Activation ◽  
Ph Values ◽  
Neutral Ph ◽  
Mammalian Tissues ◽  
Different Types ◽  
Metal Ion Activation

1. Four different types of alpha-mannosidase activity were shown to occur in several tissues from the rat. There is the Zn2+-dependent enzyme, active at acidic pH, and three enzymes that are active near to neutral pH. 2. The ‘neutral’ enzymes are activated by Fe2+, Co2+ or Mn2+. 3. Optimum activities for these three enzymes are shown at pH values of 5.2, 6.5 and 7.3. The activity at pH6.5 is the only one evident without metal-ion activation, but activity is enhanced by all three metal ions. The activity at pH 5.2 is seen only in the presence of Fe2+ or Co2+, and the activity at pH7.3 is seen only in the presence of Co2+ or Mn2+ and in a non-chelating buffer medium. 4. The pH6.5-active enzyme is inactivated by EDTA, but activity is restored by excess of metal ion. 5. The enzymes differ markedly in their stability. The pH6.5-active enzyme is very labile and the pH7.3-active enzyme is the most stable. 6. Tissue preparations vary widely in their activity at pH6.5, but where activity is low it can be increased by incubation with one of the activating metal cations. 7. All the enzymes active at neutral pH are inhibited by heavy-metal ions and stabilized to some extent by thiol groups.

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.

The sorption of lead and cadmium species by clay minerals

1977 ◽  
Vol 30 (7) ◽  
pp. 1417 ◽  
Author(s):  
H Farrah ◽  
WF Pickering
Keyword(s):  
Metal Ion ◽  
Ph Value ◽  
Cadmium Ions ◽  
Ph Values ◽  
Metal Ion Adsorption ◽  
Lead And Cadmium ◽  
Anionic Complexes ◽  
The Stability ◽  
Protonated Ligand ◽  
Ligand Species

The effect of pH changes and the presence of ligands on the uptake of lead and cadmium ions by three types of clay mineral (kaolinite, illite and montmorillonite) has been investigated. ��� In the absence of ligands, metal ion adsorption increases gradually with increasing pH until a threshold pH value is exceeded, whereupon total precipitation/sorption (attributed to formation of hydroxy species) occurs. With ligands present, the threshold point tends to shift to higher pH values, the magnitude of the effect depending on the stability of the metal complex formed. Adsorption of cationic metal complexes is subject to competition from charged protonated ligand species; anionic complexes are not sorbed.

scholarly journals Enhanced Zn2+ion-sensing behavior of a benzothiazole derivative on encapsulation by β-cyclodextrin

RSC Advances ◽  
2016 ◽  
Vol 6 (19) ◽  
pp. 15670-15677 ◽  
Author(s):  
Rajathi Queen Paulpandi ◽  
Sivaraj Ramasamy ◽  
Mosae Selvakumar Paulraj ◽  
F. Guillermo Díaz Baños ◽  
G. Villora ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Zinc Ions ◽  
Selective Binding ◽  
Benzothiazole Derivative ◽  
Ion Sensing ◽  
Enhanced Selectivity

We report, in this paper, a benzothiazole derivative which shows selective binding of zinc ions among a pool of metal ions and the enhanced selectivity of the same metal ion by the derivative in its β-cyclodextrin bound form.

scholarly journals Cu(II) and Ni(II) Interactions with the Terminally Blocked Hexapeptide Ac-Leu-Ala-His-Tyr-Asn-Lys-amide Model of Histone H2B (80–85)

2008 ◽  
Vol 2008 ◽  
pp. 1-10 ◽  
Author(s):  
Katerina Panagiotou ◽  
Maria Panagopoulou ◽  
Tilemachos Karavelas ◽  
Vassiliki Dokorou ◽  
Andrew Hagarman ◽  
...  
Keyword(s):  
Metal Ions ◽  
Binding Sites ◽  
Metal Ion ◽  
Ion Concentration ◽  
Spectroscopic Techniques ◽  
Histone H2b ◽  
Predominant Species ◽  
Ph Values ◽  
Neutral Media ◽  
Peptide System

The N- and C-terminal blocked hexapeptide Ac-Leu-Ala-His-Tyr-Asn-Lys-amide (LAHYNK) representing the 80–85 fragment of histone H2B was synthesized and its interactions with Cu(II) and Ni(II) ions were studied by potentiometric, UV-Vis, CD, EPR, and NMR spectroscopic techniques in solution. Our data reveal that the imidazole N(3) nitrogen atom is the primary ligating group for both metal ions. Sequential amide groups deprotonation and subsequent coordination to metal ions indicated an coordination mode above , in all cases. In the case of Cu(II)-peptide system, the almost exclusive formation of the predominant species CuL in neutral media accounting for almost 98% of the total metal ion concentration at pH 7.3 strongly indicates that at physiological pH values the sequence -LAHYNK- of histone H2B provides very efficient binding sites for metal ions. The imidazole pyrrole N(1) ionization (but not coordination) was also detected in species CuH-4L present in solution above .

scholarly journals Lability of Cd, Cr, Cu, Mn and Pb complexed by aquatic humic substances

2005 ◽  
Vol 30 (2) ◽  
pp. 45-51 ◽  
Author(s):  
G. R. Castro ◽  
C. C. F. Padilha ◽  
J. C. Rocha ◽  
J. P. S. Valente ◽  
A. de O. Florentino ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Metal Ions ◽  
Humic Substances ◽  
Water Samples ◽  
Metal Ion ◽  
Distribution Coefficients ◽  
Metal Exchange ◽  
Aquatic Humic Substances ◽  
Ph Values ◽  
Complexation Time

The lability of Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) complexed by humic substances (HSs) was investigated by means of ion exchange on cellulose modified with p-aminobenzoic groups (Cell-PAB), using a batch procedure. The HSs were extracted from water samples using adsorption in a column packed with XAD 8 resin. The metal-HS complexes were prepared by adding solutions containing all the aforementioned metal ions ( Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) ). The results indicated that the distribution coefficients (Kd) of Cell-PAB decreased with the presence of HSs, and that the lability of metal fractions complexed by HSs decreases in pH values > 4.0, complexation time > 10 h and HS concentration > 500 mg L-1. The metal exchange between HSs and Cell-PAB exhibited the following order of metal ion lability: Cd < Pb < Mn <FONT FACE=Symbol>@</FONT> Cr < Cu.

Adsorption Properties for Superabsorbent of Inverse Suspension Polymerization Poly(acrylate-Co-Acrylamide)

2011 ◽  
Vol 239-242 ◽  
pp. 851-854 ◽  
Author(s):  
Jian Jun Xie ◽  
Na Li ◽  
Kai Huang ◽  
Xin Qiang Han
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Selective Adsorption ◽  
Suspension Polymerization ◽  
Polymer Network ◽  
Adsorption Properties ◽  
Ph Values ◽  
Inverse Suspension Polymerization

Superabsorbent polymers are lightly crosslinked, hydrophilic polymer network having many functional groups. The adsorption properties in heavy metal ion solutions using poly(acrylate-co-acrylamide)(PAAM) are investigated. It is found that PAAM has a high uptake to heavy metal ions, and that the adsorption of heavy metal ions is greatly influenced by pH and the initial solution concentrations. The biggest and the smallest amount of adsorption are Cu2+and Cr3+in CuCl2and CrCl3solution, respectively. It was feasible for selective adsorption of the metal ions in the solution onto PAAM hydrogel by controlling the pH values of the mixing solution for CuCl2, FeCl3, CrCl3.Langmiur equatiom can satisfactorily fit for the adsorption of Cu2+while not fit for that of Fe3+and Cr3+.

Use of agro-waste (Musa paradisiaca peels) as a sustainable biosorbent for toxic metal ions removal from contaminated water

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Contact Time ◽  
Metal Ion ◽  
Equilibrium Concentration ◽  
Ion Concentration ◽  
Contaminated Water ◽  
Musa Paradisiaca ◽  
Percentage Removal ◽  
Adsorbent Dose

A study of removal of heavy metal ions from heavy metal contaminated water using agro-waste was carried out with Musa paradisiaca peels as test adsorbent. The study was carried by adding known quantities of lead (II) ions and cadmium (II) ions each and respectively into specific volume of water and adding specific dose of the test adsorbent into the heavy metal ion solution, and the mixture was agitated for a specific period of time and then the concentration of the metal ion remaining in the solution was determined with Perkin Elmer Atomic absorption spectrophotometer model 2380. The effect of contact time, initial adsorbate concentration, adsorbent dose, pH and temperature were considered. From the effect of contact time results equilibrium concentration was established at 60minutes. The percentage removal of these metal ions studied, were all above 90%. Adsorption and percentage removal of Pb2+ and Cd2+ from their aqueous solutions were affected by change in initial metal ion concentration, adsorbent dose pH and temperature. Adsorption isotherm studies confirmed the adsorption of the metal ions on the test adsorbent with good mathematical fits into Langmuir and Freundlich adsorption isotherms. Regression correlation (R2) values of the isotherm plots are all positive (&gt;0.9), which suggests too, that the adsorption fitted into the isotherms considered.

The Binding and Viscometric Studies of Ni+2, Co+2 and Mn+2 Ions with Protein by Spectrometric and pH Metric Techniques

2019 ◽  
Vol 9 (2) ◽  
pp. 151-162
Author(s):  
Shveta Acharya ◽  
Arun Kumar Sharma
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Protein Molecule ◽  
Vital Role ◽  
Sufficient Evidence ◽  
Structural Requirement ◽  
Nickel Ions ◽  
Cobalt Ions ◽  
Lower Temperature ◽  
Specific Oxidation

Background: The metal ions play a vital role in a large number of widely differing biological processes. Some of these processes are quite specific in their metal ion requirements. In that only certain metal ions, in specific oxidation states, can full fill the necessary catalytic or structural requirement, while other processes are much less specific. Objective: In this paper we report the binding of Mn (II), Ni (II) and Co (II) with albumin are reported employing spectrophotometric and pH metric method. In order to distinguish between ionic and colloidal linking, the binding of metal by using pH metric and viscometric methods and the result are discussed in terms of electrovalent and coordinate bonding. Methods: The binding of Ni+2, Co+2 and Mn+2 ions have been studied with egg protein at different pH values and temperatures by the spectrometric technique. Results: The binding data were found to be pH and temperature dependent. The intrinsic association constants (k) and the number of binding sites (n) were calculated from Scatchard plots and found to be at the maximum at lower pH and at lower temperatures. Therefore, a lower temperature and lower pH offered more sites in the protein molecule for interaction with these metal ions. Statistical effects seem to be more significant at lower Ni+2, Co+2 and Mn+2 ions concentrations, while at higher concentrations electrostatic effects and heterogeneity of sites are more significant. Conclusion: The pH metric as well as viscometric data provided sufficient evidence about the linking of cobalt, nickel and manganese ions with the nitrogen groups of albumin. From the nature and height of curves in the three cases it may be concluded that nickel ions bound strongly while the cobalt ions bound weakly.

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