DETERMINATION OF THE LEVELS OF LEAD AND ZINC IN DISCARDED PRINTED WIRE BOARDS OF MOBILE PHONES, LAPTOPS, DESKTOP COMPUTERS, TELEVISIONS, AND DVD PLAYERS


DETERMINATION OF THE LEVELS OF LEAD AND ZINC IN DISCARDED PRINTED WIRE BOARDS OF MOBILE PHONES, LAPTOPS, DESKTOP COMPUTERS, TELEVISIONS, AND DVD PLAYERS

 ABSTRACT.

 The rate at which printed wire boards (PWBs) of obsolete electrical andelectronic equipment (EEE) are being disposed into the environment is questionable. This is because PWB, contain toxic metals at concentrations that could pose human and environmental threats if not properly disposed of. This study investigated the levels of Zn and Pb, in the PWBs extracted from 35 discarded EEE (15 mobile phones, 10 laptops, 5 desktop computers, 3 televisions, and 2 DVD players). The PWBs were separately crushed with Mechanical milling machine and sieved with 2mm sieve to enable effective extraction of the metals aforementioned. All samples were weighed in duplicate making the total of 70 samples. The metals were extracted using EPA method 3051A with reverse aqua regia of ratio 3:1(HNO3and HCl acids respectively). The extracts were analyzed for Pd and Zn levels using atomic absorption spectrophotometric (AAS) technique. The results were compared with the total threshold limit concentration (TTLC) of Pb and Zn, according to the California department of toxic substance control, (DTSC, 2004). This research revealed that the 82.9% of the samples contained high level of Pb above TTLC (1000mg/kg) and 62.3% of the samples contained high level of Zn above TTLC (5000 mg/kg). This research was in agreement with previous studies. PWBs should therefore, be handled and disposed of as hazardous waste.

TABLE OF CONTENTS

CERTIFICATION…………………………………………………………………………..…...ii

DEDICATION…………………………………………………………………………………..iii

ACKNOWLEDGMENT………………………………………………………………………...iv

LIST OF FIGURES……………………………………………………………………………...ix

LIST OF PLATES.....................................................................................................................x

LIST OF TABLES……………………………………………………………………………….xii

ABSTRACT…………………………………………………………………………………….xiii

CHAPTER ONE 1

INTRODUCTION 1

1.0 Background of study 1

1.1 Heavy metals under study. 2

1.2 Statement of problem 2

1.3 Justification of study. 3

1.4.1 Aim 4

1.4.2 Objectives 4

1.5 Scope of study. 4

CHAPTER TWO 5

Literature Review 5

2.0 Literature review 5

2.1 E-waste generation in Nigeria 6

2.2 Life cycle of Electrical Electronics Equipment in Nigeria 6

2.3. Disposal Problem 8

2.4 The Hazards in E-waste 9

2.6 Printed Wire Board. 9

2.7 Heavy Metals 11

2.8 Heavy Metals Understudy 12

2.8.1 Lead (Pb) 12

2.8.2 Health Effect of Lead. 13

2.8.3 Environmental Impact of Lead 14

2.8.4 Effects of Lead on Soil 15

2.8.5 Effects of Lead on Plants 15

2.8.6 Effects of Lead on Micro-organisms and Animals 16

2.8.7 Zinc (Zn) 17

2.8.8 Health Effect of Zinc 17

2.8.9 Environmental Effect Zinc 19

CHAPTER THREE 20

MATERIAL AND METHOD 20

3.0 Sampling Collection 20

3.1 Sample Preparation 21

3.1.1 Remover of the components on the PWB. 21

3.1.2 Crushing of Samples 21

3.1.3 Sieving of Sample 23

3.2 Method 26

3.2.1 Apparatus. 26

3.2.2 Reagent 27

3.2.3 Preparation of the reverse aqua ragia 27

3.2.4 Experimental Procedures 28

3.3 Recovery Study 31

3.3.1 Procedures for recovering study. 31

3.3.2 Stock Standard Preparation. 32

3.4 Safety precaution taken 33

CHAPTER FOUR 34

RESULTS AND DISCUSSION 34

4.0 Concentration of Lead and Zinc in PWBs 34

4.1 Concentration of Lead and Zinc in phone PWB 34

4.1.1 Lead in Phone PWBs 35

4.1.2    Zinc in Phone PWB 36

4.2    Concentration of Lead and Zinc in Laptop PWB 37

4.2.1 Lead in Laptop PWB 38

4.2.2 Zinc in Laptop PWBs 39

4.3 Concentration of Lead and Zinc in Computer Desktop PWBs 40

4.3.1 Lead in Computer Desktop PWB 41

4.3.2 Zinc in Computer Desktop PWBs. 42

4.4 Concentration of Lead and Zinc in Television PWBs 43

4.4.1 Lead in Television PWBs 44

4.4.2 Zinc in Television PWBs 45

4.5 Concentration of Lead and Zinc in DVD PWBs. 46

4.5.1 Lead in DVD Player PWBs 47

4.5.2 Zinc in DVD Players PWDs. 47

4.6 SUMMARY OF RESULT DISCUSION 49

4.7 Recovery study 53

CHAPTER FIVE 54

CONCLUSION AND RECOMMENDATION 54

5.1 Conclusion 54

5.2 Recommendation 54

REFERENCE……………………………………………………………………………………55

LIST OF FIGURES

Figure 2.1: effect of Zinc intoxication and deficiency 18

Figure 4.1: Concentration of lead in phone PWB vs. TTLC of lead .36

Figure 4.2 Concentration of Zinc in Phone PWBs Vs. TTLC of zinc 37

 Figure 4.3: Concentration of lead in 10 laptop PWBs Vs. TTLC of lead 39

Figure 4.4: Concentration of zinc in 10 laptop PWBs Vs. TTLC of zinc 40

Figure 4.5: Concentration of lead in 5 desktop  PWB Vs TTLC of lead ……………….…….42

Figure 4.6: Concentration of zinc in 5 desktop PWB Vs TTLC of zinc 43

Figure 4.7: Concentration of lead in 3 televisions PWBs Vs TTLC. 45

Figure 4.8: concentration of zinc in 3 televisions PWB Vs TTLC of zinc. 46

  Figure 4.9: Concentration of lead in 2 DVD players PWB Vs TTLC……………….………...47

   Figure 4.10: Concentration of zinc in 2 DVD players PWB Vs TTLC ………………………48

  Figure 4.11: Percentage of lead and zinc in the 35 PWBs above and below the TTLC……..…51

LIST OF PLATES

Plate 1.1: Faulty PWB in a dump site ……………………………………………………………..3

Plate 2.1: idealised life cycle of E-waste in Nigeria………………………………………………7

Plate 2.2: Idealized Life cycle of e-waste in developed countries……………………………….8

Plate 2.3: Environmental impact of e-waste………………………………………………………9

Plate 2.4: Printed wire board……………………………………………………………………..11

Plate 2.5: Solid and powder form of lead………………………………………………………..16

Plate2.6:  Zinc Mineral…………………………………………………………………………..19

Plate 3.1: samples before unsoldering…………………………………………………………...20

Plate 3.2: Samples after unsoldering……………………………………………………………..21

Plate 3.3: Mechanical milling machine…………………………………………………………..22

Plate 3.4: Sample after crushing and before sieving ……………………………………………23

Plate 3.5: 2 mm British Standard sieve…………………………………………………………..24

Plate 3.6: Piston and a mortal……………………………………………………………………24

Plate 3.7: Sample after Sieving…………………………………………………………………..25

Plate3.8: Preparation of Aqua regia……………………………………………………………...28

Plate 3.9: Samples on the hotplate ready for digestion…………………………………………..29

Plate 3.10: Sample filtration……………………………………………………………………..29

Plate 3.11: Addition of distilled water into the sample to make it

up to 100ml in 100ml volumetric flask…………………………………………………………..30

Plate19: Samples in heavy metal sampling bottles ready for AAS analysis. ……………………30

                                                       LIST OF TABLES

Table 3.1: Samples, model and year of manufacture…………………………………………….25

Table 4.1:  showing the Concentration of Pb and Zn in Phone PWBs………………………….35

Table 4.2: concentration of lead and zinc in laptop PWBs………………………………………38

Table 4.3: Concentration of lead and zinc in PWBs of computer desktop……………………..41

Table 4.4: Concentration of lead and zinc in 3 television PWBs………………………………..44

Table 4.5: Concentration of 2 DVD player PWBs……………...……………………………….46

Table 4.6: Summary of results………………………………………………………….………..49

Table 4.7:  Result of Recovery Study…………………………………………………………...53

.

DETERMINATION OF THE LEVELS OF LEAD AND ZINC IN DISCARDED PRINTED WIRE BOARDS OF MOBILE PHONES, LAPTOPS, DESKTOP COMPUTERS, TELEVISIONS, AND DVD PLAYERS



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