Evaluation of Pb and Cu contents of selected component parts of waste personal computers

K Olubanjo,O Osibanjo,Ni Chidi

doi:10.4314/jasem.v19i3.17

Abstract

Electronic waste (e-waste) is one of the fastest growing waste streams in the world. The increasing market penetration in developing countries such as Nigeria, replacement market in developed countries and high obsolescence rate, make e-waste one of the fastest growing waste streams. Thirty five (35) units of waste computer central processing unit (CPU) and 24 units of waste computer monitors of different brands, manufacturers, year of manufacture, and model were collected from different electronic repairers’ shops in Ibadan, South-western Nigeria and investigated for the lead and copper contents. The devices were disassembled and the printed wiring boards (PWB) of the CPUs and monitors; and the cathode ray tube (CRT) of the monitor were milled and representative samples digested with a mixture of HNO 3 -H 2 O 2- HCl and analysed using Atomic Absorption Spectrophotometry (AAS). The results showed very high levels of Cu and Pb in the samples with Cu concentrations ranging from 83100-705300 mg/kg for PWB of CPUs, 39150-630300 mg/kg for PWB of monitors and 73.2-468 mg/kg for CRT. The Pb contents varied from 18060-400650 mg/kg for PWB of CPU, 8460-80850 mg/kg for PWB of monitor and 429-9900 mg/kg for CRT. The results exceeded the Toxicity Threshold Limit Concentration (TTLC) used in characterizing wastes as toxic. The adoption of inappropriate methods in the management of these wastes could result in environmental pollution and human exposure to toxins. Consequently, appropriate measures should be adopted to manage these wastes as hazardous wastes. Keywords : personal computers, printed wiring board, computer monitor, lead, copper,

Highlights

The results show (Table 3) that the lead and copper contents in the printed wiring board (PWB) of the Central Processing Unit (CPU) of all the samples exceed the threshold limits for these metals by 400 times and 282 times respectively, while in the printed wiring board of the monitors, the threshold limit was exceed by 81 times and 252 times respectively
It was observed that the copper content in the cathode ray tube (CRT) is far below the threshold limit for all the samples, while lead content is very high in this part of the component, exceeding the regulatory limit by 10 times
A comparison of our computer data used for this study and other e-waste analyses (Lincoln et al, 2007) indicate that the two elements are above the regulatory limit, though at a lower concentration of 81 times for Cu as compared to 282 times for Cu in the printed wiring boards (PWB) of the central processing unit (CPU) and 252 times in the PWB of monitor for the present study, but lead was found to be 10 times more than the regulatory limit, which is the same value obtained for lead in CRT in the present study

Summary

Introduction

*1OLUBANJO, K; OSIBANJO, O2; NNOROM, I.C2,3 separately and the components were classified into two major parts: Millable parts: Printed wire boards (PWBs including IC packages) for the CPU, monitor, and CRT Non-millable parts: Metal frames, rods and other metal parts. Instrumental analysis: All the sample solutions were analysed for lead and copper with flame atomic absorption spectrophotometer using appropriate lamps and resonance wavelength of the metals.

Results

Conclusion