ORIGINAL PAPER Electrochemical detection and removal of lead in water using poly(propylene imine) modified re-compressed exfoliated graphite electrodes Thabile Ndlovu • Omotayo A. Arotiba • Srinivasan Sampath • Rui W. Krause • Bhekie B. Mamba Received: 27 June 2011 / Accepted: 27 September 2011 / Published online: 12 October 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Modification of exfoliated graphite (EG) electrode with generation 2 poly(propylene imine) dendri- mer by electrodeposition resulted in an electrochemical sensor which was used to detect lead ions in water to a limit of 1 ppb and a linear response between 2.5 and 40 ppb using square wave anodic stripping voltammetry (SW-ASV). Pb(II) was also removed from spiked water sample using a 40-mm diameter unmodified EG electrode with an applied potential of -1,000 mV for 180 min. A removal efficiency of 99% was calculated from a 150 mL sample. The results obtained in both cases using SW-ASV, correlated with atomic absorption spectroscopy. Keywords Exfoliated graphite  Lead  Poly(propylene imine) dendrimer  Square wave anodic stripping voltammetry  Water 1 Introduction The presence of heavy metals in the environment and their potentially toxic effects on the health of living species is a cause for concern. This is because heavy metals tend to bioaccumulate in higher trophic levels within the food chain and can be toxic even in trace quantities [1–3]. Therefore, the challenge to remediate hazardous metal- containing waste streams generated by mining operations, industrial sites and groundwater is immense. Almost all heavy metals are toxic and excess levels are known to cause both acute and chronic health conditions [4]. Heavy metals cannot be degraded and the natural process of metal mineralisation is very slow [5]. Fundamentally, the removal of heavy metals from water and wastewater is best accomplished by immobilisation and concentration on suitable sorbents whereby the sorbed metals can be removed and reused as raw materials [4]. Since heavy metal ions which are generated in wastewater during industrial processing are extremely toxic to the environ- ment and humans, it is very important that treatment be provided in such a way that their pollutant loads are kept at low concentration levels before being discharged into sewers or water systems [1]. Lead (Pb), a heavy metal, is widely used in industries and it is a well-known water pollutant. Lead poisoning is associated with gastrointestinal disorders, constipation, abdominal pain and central nervous system effects [4]. The harmful effect of Pb on child development can occur without clinical symptoms and might not present any abnormalities during routine testing. However, higher levels or prolonged exposure to Pb result in more severe symptoms such as kidney and nervous system damage [4–6]. These adverse health effects necessitated extensive attention in developing sensitive, reliable and rapid ana- lytical methods [7]. Electrochemistry can be used for the treatment or recovery of pollutants in effluents from industries and municipal plants. Electrochemical devices are effective and inexpensive for environmental monitoring of an increasing range of toxic substances [8]. With its unique ability to oxidise or reduce compounds at a well-controlled electrode potential and by just adding (at the anode) or withdrawing T. Ndlovu  O. A. Arotiba (&)  R. W. Krause  B. B. Mamba Department of Chemical Technology, University of Johannesburg, Doornfontein, PO Box 17011, Johannesburg 2028, South Africa e-mail: oarotiba@uj.ac.za S. Sampath Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India 123 J Appl Electrochem (2011) 41:1389–1396 DOI 10.1007/s10800-011-0360-6