The Use of Activated Charcoal for Preconcentration of Trace Heavy Metals from River Water in their Analysis by Thermal-Neutron Activation

Abstract

The use of activated charcoal in the separation of some trace heavy metals from water and subsequent analysis by neutron activation has been investigated. The recovery is quite good for As, Cr, Hg and Zn at pH between 8 and 8.5 but poor for Co, Cu, Cd and Sb. Co, Cu and Zn are efficiently adsorbed after complexation with ammonium-pyrrolidinedithiocarbamate at pH 4.5 and 6.5. In both cases about 0.5 g activated charcoal is sufficient for 1 litre water. The procedure is applied to the determination of As, Cr, Hg, Cu, Co and Zn in the polluted Ogba River, the present main source of tap water supply to Benin City. The measured high levels of these metals especially As, Cr and Cu are attributed to contamination due to the effluents from a nearby Wood Preservative Treatment Factory.

Key Words:

• Activated charcoal
• preconcentration
• trace-metals
• water.