Heavy Metal Concentration of Surface Dust Present in E-Waste Components: The Westminister Electronic Market, Lagos Case Study

To evaluate the extent of heavy metals (Cd, Cr, Pb, Zn, Fe) contamination from e-waste, surface dust samples were collected from workshops (indoor), around the market areas (outdoor) and from a distance of about 100 metres away from the market area (control) of the Westminister Electronic market in Lagos, Nigeria. Aqua regia digestion was applied to the dust samples prior to determination of heavy metal by atomic absorption spectroscopy (AAS). The AAS analysis revealed mean concentrations in indoor dust (Pb 22.50, Cd 1.80, Fe 108.00, Cr 0.35 and Zn 295.50 mg/kg), outdoor dust (Pb 15.90, Cd 19.00, Fe 103.3, Cr 0.10 and Zn 213.00 mg/kg) and control dust ( Pb 9.40, Cd -, Fe 62.00, Cr – and Zn 78.00 mg/kg). Although the result showed a relatively low contamination in general, it could be inferred that the increased concentration of heavy metals from the indoor electronic waste could be from the interaction of heavy metals in the e-waste components with the settled dust on them over time. Risk assessment predicted that Cd and Zn in the e-waste have the potential to pose serious health risks to workers, customers and local residents of Westminister area, especially children, and this underscores the urgent intervention by relevant government agencies

Comparison of Three Methods of Digestion for Trace Metal Analysis in Surface Dust Collected from an Ewaste Recycling Site

The recycling of e-waste materials potentially contaminates the environment with heavy metals. Analysing the exact contents of heavy metal in e-waste products is germane for the routine monitoring, risk assessment and regulation of the environment. Therefore, the efficiency of three methods of digestion was evaluated for Cd, Fe, Pb, Cr and Zn by AAS in surface dust from an e-waste recycling site and to recommend the most efficient digestion method. The digestion methods were aqua regia, dry ashing followed by aqua regia and nitric acid digestion followed by extraction with HCl. Analysis of variance, Student’s t-test and F-test were performed separately for the indoor, outdoor and control dust samples analytical result. Analytical results indicated that the nitric acid digestion followed by extraction with HCl was the most efficient in recovering Pb and Fe based on recovery efficiency. Aqua regia was found to be an alternative method for recovering Pb and Fe based on cost and time effectiveness. Aqua regia was the most efficient in recovering Zn while aqua regia and nitric acid digestion followed by extraction with HCl were satisfactory for the recovery of Cd. Dry ashing followed by aqua regia was found unsuitable for the analysis of these metals in the samples because it recovers relatively little heavy metals and more analysis time