I= STUDIES ON THE SOURCES OF METALS LIKE CHROMIUM, NICKEL AND LEAD IN THE ENVIRONMENT AND THEIR DETOXICATION
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Title of Thesis
STUDIES ON THE SOURCES OF METALS LIKE CHROMIUM, NICKEL AND LEAD IN THE ENVIRONMENT AND THEIR DETOXICATION

Author(s)
Shahida Gulzar
Institute/University/Department Details
University of Karachi/ Department of Chemistry
Session
2000
Subject
Chemistry
Number of Pages
168
Keywords (Extracted from title, table of contents and abstract of thesis)
chromium, nickel, lead, detoxication, polyaminocarboxylic acids, toxicity, heavy metal, pac acids, cdta, dtpa, edta

Abstract
Using Polyaminocarboxylic acids like CDTA, DTPA & EDTA for detoxification of Pb(II), Za(II) & Cr (III&VI) in presence of essential ions e.g. Fe(III), Za(II)& Ca (II), their complexation of different pH was studied potentiometerically. DTPA was found comparatively stronger acid than CDTA & EDTA as it showed maximum complexation with Fe(III),Zn(II) & Pb (II) at pH below 2, Competiton of selected metals soward PAC acids with respect to concentration ratio at different pH as well as selection of the conditions for the complexation of toxic metals with PAC acids in presence of essential metals were also discussed. PAC complexes of Fe(III) were studied & Fe(III) DTPA was selected as target compound for spectrophotometeric study at max 440mm. Quantitatively determined the percentages of exchange of Fe(II),Za(II) & Ca(II) on addition of Pb(II),Ni(II)& Cr(III&VI), At Ph 4,7 & 9 at 30 C, when Ni (II) was added to iron complex, 63 to above 90% Fe (III) was exchanged wheread Chromium couldnot manage to exchange iron from its complex. During the competition of Fe(III)&Pb(II) at pH 7&9 at 30’C, 65-90%of iron was exchanged from its DTPA complex, further increase was expected on raising the temperature to 60 C while from its CDTA complex, only 40% iron was removed. On interaction of Zn(H) was replaced with Pb(II) of pH 9 at max 250mm & 30”C,95% of Za(II) was replaced with Pb(II),Similarly the displaced amount of Ca(II) from its complex on additions of Pb(II) was 93% under similar experimental conditions.

To make Cr(VI)less toxic, an antioxidant like ascorbic acid was used and redox potential of CDTA & DTPA complexes were determined at pH 4 & 7, PAC acids also have been used and compared as autioxidant at pH 2,4 & 7.DTPA might successfully reduce Cr(VI) at lower pH i.e. 0.1M HCI solution. Finally the domestic industrial effluents were analyzed to determine the above mentioned toxic ions by absorption spectrophotometer

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
107.13 KB
2 1 Environmental Sources Of Lead 2
133.57 KB
  1.1.1 Exposure To Lead 3
  1.2 4
  1.3 Environmental Sources Of Chromium 6
  1.4 Domestic Sources 7
3 2 Biological Activities Of Metals 14
304.54 KB
  2.1 Role Of Metal 14
  2.2 Metal Ion Induced Toxicity 15
  2.3 Essential Beneficial And Toxic Metal 15
  2.4 Binding Groups For Metals In Biological System 24
  2.5 Toxicity Of Heavy Metals 25
  2.6 Different Correclation Between Ld 50 Valuesof Toxic Metals And Their Different Chemical Parameters 27
  2.7 Environmental Factors Affecting Toxicity 28
  2.8 Chemical Speciation 29
  2.9 Detoxification Of Heavy Metal Ions 31
  2.10 Pac Chelates Of Metals 33
  2.11 Literature Survey On Heavy Metal Intoxication By Hydrophilic Drugs 34
  2.12 Comparison Of Pac Acids (Hydrophilic Chelating Agents 36
  2.13 Aim & Scope Of The Study 38
4 3 Methods And Materials 48
148.44 KB
  3.1 Potentiometeric Methods 48
  3.2 Spectrophotometeric Methods 49
  3.3 Materials 53
  3.4 Instrumentation 53
  3.5 Preparation Of Reagents 54
  3.6 Potentiometeric Study 58
  3.7 Spectral Study 61
5 4 Result And Discussion 67
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  4.1 Potentiometeric Study 68
  4.2 Spectrophotometeric Study 79
  4.3 Determination Of Heavy Trace Metals Like Pb(Ii) N(Ii) And Cr(Iii,Vi) From The Industrial Effluents By Atomic Absorption Spectrophotometery 157
  4.4 Conclusion 159
6 5 Future Directions 162
13.1 KB
7 6 References 163
152.77 KB
  6.1 Appendices