K 0-INAA measurement of levels of toxic elements in oil sludge and their leachability

Abstract

Development of the petroleum industry has resulted in increasing production of oil sludge, the disposal of which risks introducing hazardous elements into the environment. In the frames of these studies the presence of the toxic metals arsenic, chromium and zinc in oil sludge and the leachability of those toxins. Samples were obtained from a refinery plant in Sg Udang, Melaka and from the Miri Crude Oil Terminal, Sarawak, both in Malaysia. k0-Instrumental Neutron Activation Analysis was used to measure mass fractions of elements. The samples were packed and irradiated in a TRIGA Mark II reactor. Mass fraction of arsenic in the oil sludge samples were found to be higher than the EPA pollutant mass fraction limit; mass fractions of chromium and zinc were below of this limit. Samples were also tested for leachability, which was found to be contributed to by controlled diffusion. Slow leachability of arsenic was found to be higher than the EPA limit in these oil sludge samples, influenced by such factors as redox condition. It was found however, that the most leachable of these elements in all samples from both sites was zinc, followed by arsenic and chromium, indicating that zinc may present a more serious threat of environmental contamination than the other two.