Michael Adekunle Olatunji

Influence of adsorption parameters on cesium uptake from aqueous solutions- a brief review

Due to rapid population growth, technological advancement and industrial revolution, the rate of generated waste effluents has become a grave concern. Cesium which possesses high fission yield is generally transferred to liquid wastes especially those emanated from the nuclear power plants, reprocessing of spent fuels, nuclear weapon testing and radionuclides production facilities for medical applications etc. Radiocesium (137Cs) is one of the hazardous radionuclides creating adverse effects on human health and environment. Due to its physical (T1/2 = 30.17y) and chemical characteristics (alkalinity, solubility etc.), it can be easily assimilated by the living organisms. As a result, the removal of cesium from wastewater is imperative from the health point of view. Several techniques are implemented but in recent time, adsorption has been gaining increasing attention to the scientific community owing to a number of reasons. Hence, this paper presents an overview on sorption of cesium from wastewaters. Consequently, several critical parameters such as sorption capacity, percentage efficiency and the influence of several factors on cesium uptake by various adsorbents have been reviewed in details.

Evaluation of radionuclides transfer from soil-to-edible flora and estimation of radiological dose to the Malaysian populace

Malaysia, a rapidly growing industrial country, is susceptible to pollution via large-scale industrial engagements and associated human activities. One particular concern is the potential impact upon the quality of locally resourced vegetables, foodstuffs that contain important nutrients necessary for good health, forming an essential part of the Malaysian diet. As a part of this, it is of importance for there to be accurate knowledge of radioactive material uptake in these vegetables, not least in respect of any public health detriment. Herein, using HPGe γ-ray spectrometry, quantification has been performed of naturally occurring radionuclides in common edible vegetables and their associated soils. From samples analyses, the soil activity concentration ranges (in units of Bq/kg) for (226)Ra, (232)Th and (40)K were respectively 1.33-30.90, 0.48-26.80, 7.99-136.5 while in vegetable samples the ranges were 0.64-3.80, 0.21-6.91, 85.53-463.8. Using the corresponding activities, the transfer factors (TFs) from soil-to-vegetables were estimated, the transfers being greatest for (40)K, an expected outcome given the essentiality of this element in support of vigorous growth. The TFs of (226)Ra and (232)Th were found to be in accord with available literature data, the values indicating the mobility of these radionuclides to be low in the studied soils. Committed effective dose and the associated life-time cancer risk was estimated, being found to be below the permissible limit proposed by UNSCEAR. Results for the studied media show that the prevalent activities and mobilities pose no significant threat to human health, the edible vegetables being safe for consumption.

Natural radioactivity and effective dose due to the bottom sea and estuaries marine animals in the coastal waters around Peninsular Malaysia

Malaysia is among the countries with the highest fish consumption in the world and relies on seafood as a main source of animal protein. Thus, the radioactivity in the mostly consumed marine animals such as fishes, crustaceans and molluscs collected from the coastal waters around Peninsular Malaysia has been determined to monitor the level of human exposure by natural radiation via seafood consumption. The mean activity concentrations of naturally occurring radionuclides (226)Ra ((238)U), (228)Ra ((232)Th) and (40)K ranged from 0.67 ± 0.19 Bq kg(-1) (Perna viridis) to 1.20 ± 0.70 Bq kg(-1) (Rastrelliger), from 0.19 ± 0.17 Bq kg(-1) (Teuthida) to 0.82 ± 0.67 Bq kg(-1) (Caridea) and from 34 ± 13 Bq kg(-1) (Caridea) to 48 ± 24 Bq kg(-1) (Teuthida), respectively. The mean annual committed effective dose due to the individual radionuclides shows an order of (228)Ra > (226)Ra > (40)K in all marine samples. The obtained doses are less than the global internal dose of 290 µSv y(-1) set by the United Nations Scientific Committee on the Effects of Atomic Radiation, discarding any significant radiological risks to the populace of Peninsular Malaysia.

Radiological study on newly developed composite corn advance lines in Malaysia

Owing to population growth, there has been high demand for food across the world, and hence, different agricultural activities such as use of phosphate fertilizers, recycling of organic matters, etc, have been deployed to increase crop yields. In Malaysia, a total of nine composite corn advance lines have been developed at the Institute of Biological Sciences, University of Malaya and are being grown under different conditions with a bid to meet the average daily human need for energy and fiber intake. To this end, the knowledge of radioactivity levels in these corn advance lines are of paramount importance for the estimation of possible radiological hazards due to its consumption. Hence, the radioactivity concentrations of 226Ra, 228Ra and 40K in the corn have been determined using HPGe γ-ray spectrometry. The activity concentrations in the corn ranged from 0.05 to 19.18 Bq kg−1 for 226Ra, from 0.10 to 3.22 Bq kg−1 for 228Ra and from 26.4 to 129 Bq kg−1 for 40K. In order to ascertain the radiological safety of the population regarding maize consumption, the daily intakes of these radionuclides as well as the annual effective dose were estimated. The total effective dose obtained due to the ingestion of radionuclides via maize consumption is 15.39 μSv y−1, which is less than the international recommendations.

Cadmium-109 Radioisotope Adsorption onto Polypyrrole Coated Sawdust of Dryobalanops aromatic: Kinetics and Adsorption Isotherms Modelling

A radiotracer study was conducted to investigate the removal characteristics of cadmium (109Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited 109Cd removal from its aqueous solution. The experimental data for 109Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor’s materials and the toxicity of 109Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of 109Cd radioisotope from radionuclide-containing effluents.

Polypyrrole-based nanocomposite adsorbents and its application in removal of radioactive materials

Abstract Conducting polymers form an important aspect of research in science and engineering due to their various interesting properties, such as inherent high flexibility, structural diversity, light weight, and mechanical stability. Among them, polypyrrole due to its facile and easy synthesis at low cost, high electric conductivity, environmental friendliness, and ease of tailoring into nanocomposites has expanded its applications beyond the original scope of conventional polymers. Considering these properties, incorporation of nanofillers in polypyrrole for fabricating polypyrrole-based nanocomposites is currently receiving immense attention as beneficial resources for developing high-efficient adsorbents for addressing environmental issues. This chapter focuses on the synthesis of polypyrrole and its nanocomposites and the key issues for achieving high performance in the treatment of liquid radioactive wastes. Survey of literature on the recent studies on the uptake of radioactive materials and their nonradioactive homologues via applications of polypyrrole-based nanocomposite adsorbents was made. Finally, general outlook of the future prospects of polypyrrole-based nanocomposites in the removal of radioactive materials and possible problems they may encounter is presented.

Radiation dose to Malaysian infants from natural radionuclides via consumption of powdered milk

Milk is the basic food stuff for the infants because they generally consume more milk on a daily basis as its minerals and proteins are essential for their growth and development, therefore, it is very important to assess the natural radioactivity levels and the associated dose in the widely consumed powered infant’s milk. As a result, 14 brands of infant’s powdered milk were collected from different supermarkets around Selangor, Malaysia and analysed for 226Ra, 232Th and 40K activities. The obtained mean activity of 226Ra, 232Th and 40K are 3.05±1.84, 2.55±2.48 and 99.1±69.5 Bqkg−1, respectively. Among the analysed milk samples, the brand from Philippines (Lactogen) showed low level of radioactivity while Singaporean brand (S26 SMA Gold) showed the highest. The estimated mean annual effective doses due to the ingestion of natural radionuclides in the sampled milk are 635 and 111 µSv for infant ≤ 1y and infant 1-2y, respectively. The obtained dose value does not yet pose any significant radiological hazar...

Development and Characterization of Polypyrrole-Based Nanocomposite Adsorbent and Its Applications in Removal of Radioactive Materials

Development of environmental friendly materials is desirable in the fields of science and engineering for various purposes. In environmental science, they find applications commonly in environmental remediation and the recovery of valuable metals. This aspect is of particular concern to health sciences due to the toxic effects and non-biodegradable nature of many substances that have found their way into the human body via environmental media. As for instance, though cobalt possesses some importance in diet it has been linked to health problems like cardiomyopathy, asthma etc. via overexposure. As a result, removal of this substance from the aqueous media of our environment is crucial. In this study, polypyrrole conducting polymer incorporated with biomass waste (sawdust) was prepared by simple chemical oxidative polymerization as a composite adsorbent for 57Co radionuclide removal from aqueous solution. The as-prepared composite material was characterized by FESEM, XRD and BET surface analysis. In the 57Co adsorption studies, the effects of several factors such as adsorbent dosage, contact time and competitive metal ions were investigated for real wastewater treatment applications. The results indicated that the removal process was rapid and reached saturation within 3 hours of contact of adsorbent and adsorbate at ambient temperature. Both Na+ and K+ coexisting ions were found to affect 57Co adsorption and the uptake percentage was reduced from 54.9 to ~ 20% at 0.1M of both Na+ and K+ ions. Langmuir isotherm model was used to fit the maximum sorption capacity.