Assessment of Leaching of some Heavy Metals from Domestic Ceramic Wares

Abstract

The aim of this study is to assess the possible leaching of heavy metals from ceramic wares into different solutions. Ceramic spoon, pot, soup bowl, plate, mug and cup were leached in batch process using hot water and 4 % solutions of glacial acetic acid, HCl acid, NaOH and Na₂CO₃ respectively. Chromium, manganese, lead, cadmium, zinc and copper which were incorporated as glazes in the ceramic wares were determined in the leachates using atomic absorption spectrophotometric technique. The metal concentrations in the leachates ranged between 101.565-233.010 mg/kg for chromium, 44.333-1449.047 mg/kg for manganese and 0.235-6.260 mg/kg for copper. The levels of manganese and copper in the ceramic wares analyzed were above the permissible limits of World Health Organization (WHO) and Society of Glass and Ceramic Decorators. The levels of chromium in the wares with the exception of mug were also above the permissible limits. The results highlight that hot drinks, acidic and alkaline solutions can easily induce leaching of metals from ceramic wares at concentrations higher than permissible limits. The results also indicate 4 % NaOH solution as the most aggressive leachant while hot Lipton tea was the least aggressive. Alkaline leachant solution leached Cu and Cr metals more than other solutions, though statistical analysis of the data did not indicate any significant difference between the leachant solutions. The highest percentage of metals leached were 96 % (Cr), 92 % (Mn) and 86 % (Cu) from pot and soup bowl respectively. Consumption of stored food and drinks from these ceramic wares may be associated with health implications owing to the toxicity of the metals at elevated concentrations.