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Title of Thesis

Detection Of Heavy Metals And Other Contaminants In Solid And Liquid Samples Using Laser Induced Breakdown Spectroscopy

Author(s)

Talib Hussain

Institute/University/Department Details
Institute of Environmental Science & Engineering / National University of Sciences and Technology, Rawalpindi
Session
2008
Subject
Environmental Engineering
Number of Pages
218
Keywords (Extracted from title, table of contents and abstract of thesis)
Detection, Heavy Metals, Solid, Liquid, Laser, Breakdown, Spectroscopy, ambient, temperature, industrial

Abstract
In this work, Laser-Induced Breakdown Spectroscopic Technique was applied for detection of heavy metals and other contaminants in solid and liquid samples. This technique was applied for qualitative as well as quantitative measurement of elemental concentration present in test samples. A special chamber was designed and fabricated for analysis of solid samples in which provisions were made for insertion of sample, its rotation, evacuation, and introduction of various gases at different pressures. The LIBS system was calibrated and applied for determination of contaminants present in the samples in the pellet forms. Then the system was applied for sample collected from sites such as crude oil waste dump, greenhouse soil, oil spilled contaminated site, mine ore waste, iron slag, and chromium contaminated site from different locations of Saudi Arabia. The role of various binding material in the LIBS performance for trace elemental
analysis of powder samples was also investigated.
The influence of ambient environment such as pressure, temperature, nature of buffer gas on emission feature of solid sample was studied as well. Prior to LIBS application to the actual samples, the important parameters influencing LIBS performance were optimized. In this regard the effect of laser energy, distance between fiber optics and target material, limit of detection, precision, accuracy, repeatability,
delay time were optimized. The concentrations detected with our LIBS system were verified by the conventional method such as ICP and the relative accuracy of the system for various elements was compared and found in the range of 0.03 - 0.6 at 2.5 % error confidence. Most of the elements under investigation showed maximum signal intensity at delay time between 4.0 and 5.5 Ás and laser pulse energy between 20 mJ to 140 mJ. Prior to application of LIBS the plasma parameters such as temperature and electron density were also measured as these parameters play vital role in the sensitivity of LIBS system. The plasma temperature for iron slag sample was estimated using Boltzman plot of LIBS intensity for neutral iron lines and Stark broadening. The maximum plasma temperature and electron densities at 40 mJ energy was 5554 K and 1.46 x 1016 cm-3, respectively for these samples.
In order to analyze the liquid samples different setups were developed and tested. The aim of fabricating the setup for liquid samples analysis was to keep the LIBS system simple, and to improve accuracy & limit of detection of elements under investigation. Calibration curves for metals of interest were drawn from standard solution of these metals in distilled water. Later, the system was pplied for quantitative detection of contaminants in wastewater samples collected from paint industry, syringe manufacturing industry and dairy plant. The results obtained with our LIBS setup were comparable with that obtained from ICP. The experience gained through this work can be useful for the development of a portable LIBS system for on-line analysis of contaminated sites with heavy metals for improvement of the environment and controlling the pollution at industrial sites.

Download Full Thesis
2,680 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 CONTENTS

 

viii
15.3 KB
2

1

INTRODUCTION

1.1 Overview

1.2 Objective

1.3 Thesis Organization

1
135 KB
3 2 LITERATURE REVIEW

2.1 Laser Induced- Breakdown Spectroscopy

2.2 Capabilities of LIBS

2.3 Instrumentation of LIBS

2.4 Advantages and Disadvantages of LIBS

2.5 Application of LIBS

6
200 KB
4 3 THEORETICAL BACKGROUND

3.1 Interaction of Laser Beam with Matter

3.2 Plasma Temperature

3.3 Electron Density

3.4 Effect of Ambient Conditions on LIBS Performance

3.5 Crater Depth

3.6 Role of Binding Materials

32
219 KB
5 4 EXPERIMENTAL SET UP AND PROCEDURE

4.1 Components

4.2 Characterization and Analysis Procedure

4.3 Samples Preparation

4.4 Liquid Samples

48
267 KB
6 5 RESULTS AND DISCUSSION

5.1 Optimization of Various Parameters of LIBS

5.2 Role of Various Binding Materials

5.3 Plasma Temperature (Iron Slag Sample)

5.4 Electron Density

5.5 Calibration Curves for Solid Samples

5.6 Limit of Detection

5.7 Study of Ambient Gas Pressure Effect on LIBS Performance

5.8 Liquid Samples

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7 6 ENVIRONMENTAL APPLICATIONS OF LIBS SYSTEM

6.1 Detection of Nutrients in Greenhouse Soil

6.2 Ore Sample

6.3 Analysis of Iron and Steel Plant Slag

6.4 Monitoring of Chromium in Contaminated Site

6.5 Determination of Chloride in Various Types of Cements

6.6 Gulf Oil Spilled Contaminated Soil

6.7 Detection of Heavy Metals in Crude Oil Residue

6.8 Analysis of Paint Manufacturing Plant Wastewater

6.9 Detection of Hazardous Metals in Plastic Syringes Plant Wastewater

6.10 Dairy Product Plant Wastewater

103


1,784 KB
8 7 CONCLUSION AND RECOMMENDATIONS

7.1 Conclusions

7.2 Recommendations for Future Research Work

180


103 KB
9 8 REFERENCES & APPENDICES

184


121 KB