Abstract
M.Tech. (Chemistry)
This study developed carbon nanocomposite modified on exfoliated graphite electrodes that are sensitive and selective for the electrochemical detection of mercury and arsenic. This research explores the new material called exfoliated graphite for the detection of heavy metals in water. The material is relatively cheap and is a promising material for the detection of heavy metals. The exfoliated graphite was prepared by intercalation of natural graphite flakes with a particle size of 300 μm by soaking them in a mixture of concentrated acids, sulphuric acid and nitric acid in the ratio 3:1 respectively. After the intercalation the resulting material was exfoliated. The exfoliation was achieved by subjecting the intercalated graphite to high temperatures of 800 ºC in a furnace for about 30 seconds. The puffed up material was named exfoliated graphite (EG). The EG was compressed into pellets of 5mm using high pressure hydraulic press. The mercury nanocomposite sensor was designed by incorporation of carbon nanotube/polyaniline (CNT/PANI) composite followed by electrodeposition of gold nanoparticles onto the EG electrode. This electrode was named CNT/PANI/AuNPs-EG. The dispersion of carbon nanotubes onto the polymer was obtained via the in situ polymerization method. This electrode was name CNT/PANI/EG. The electrodeposition of gold nanoparticles was achieved by preparing 5 mM of HAuCl4 solution and cycling the potential from -200 mV to 1100 mV for 10 cycles at a scan rate of 50 mV/s. this electrode was used for the detection of mercury in water. The detection limit was calculated to be 0.046 ppb (0.229 nM) and the limit of quantification was 0.152 ppb with a correlation coefficient of 0.9984. Another electrode was prepared for the detection of arsenic. Reduced graphene oxide/cobalt nanoparticles modified on EG electrode. A good detection limit and limit of quantification were found to be 0.31 ppb and 1.01 ppb respectively. The linear regression equation was 𝑦=6.64608×10−4 𝑥+1.96169×10−5 with a high correlation coefficient of 0.9984.