Accumulation of some toxic mineral elements in selected foods marketed in Nigeria

Levels of iron, copper, zinc, manganese, lead, cadmium and nickel in selected foods marketed in Nigeria were determine by atomic absorption spectrometry following wet digestion with a mixture of nitric, perchloric and sulphuric acids (3:2:1). Sixteen fresh an canned food samples were purchased at supermarket stores and local markets in and around Owerri, Nigeria and analysed for levels of the indicated elements. The results showed that the levels of Cd, Pb, Ni, Mn, Cu, Fe, and Zn were 0.16–0.33, 1.63–4.50, 0.06–1.11, 0.19–33.3, 0.12–5.20, 0.52–233.3 and 0.46–19.6ppm, respectively. Marked variations were observed in the levels of elements determined in all the food samples analyzed as indicated by the high coefficient variation. Dietary implications of these metals are also discussed. Keywords: toxin, mineral elements, food, Nigeria Plant Products Research Journal Vol. 8(1) 2004: 18-2

Heavy meal decontamination of polluted soils using Bryophyllum pinnatum

Phytoremediation was carried out with Bryophyllum pinnatum as a means of cleaning up soils contaminated with heavy metals. Maximum levels of metals accumulated were Ni (11.91 mg/kg), Pb (399.90 mg/kg), Cr (32.48 mg/kg), V (5.81 mg/kg) and Cd (3.12 mg/kg) and this occurred in the 4th month of study. Results of this study indicate that B. pinnatum is an efficient metal hyperaccumulator for phytoremediation of metal contaminated soils

Fluorescence Studies of Binding of Dansylglycine and Dicoumarol to Bovine Serum Albumin

Dansylglycine was used as a fluorescent probe to study the binding of dicoumarol to bovine serum albumin (BSA) at pH 7.4. The fluorescence of dansylglycine was greatly enhanced on binding to BSA with a blue shift in wave-length of the emission maximum. Fluorescence data indicated that dansylglycine was bound tightly to one high-affinity binding site with an association constant of (2.6 ± 0.2) x 106 M-1 in addition to several low-affinity secondary sites. The fluorescence of dansylglycine: BSA complex was quenched by the binding of dicoumarol. This indicates a competition for the binding sites between dicoumarol and dansylglycine in favour of dicoumarol. The fluorescence quenching data indicated that BSA had one high - affinity binding site for dicoumarol with an association constant of (1.46 ± 0.03) x 106 M-1. It was concluded that the binding sites for these drugs are located in the hydrophobic region of BSA. Key Words: Bovine Serum albumin, dansylglycine, dicoumarol, hydrophobic sites. Bio-Research Vol.2(1) 2004: 124-13

Cadmium (II) Adsorption from Aqueous Solutions Using Onion Skins

Staff PublicationThe potential of onion skins for removal of aqueous Cd(II) was investigated. Onion skin powder was chemically modified using thioglycolic acid to develop a suitable, low-cost, and efficient adsorbent for the removal of Cd(II) from aqueous solutions. Influences of temperature, contact time, initial concentration of Cd(II), adsorbent dosage, and pH on the removal of Cd(II) were probed. Optimal adsorption conditions were found at pH 5 and 4, and at 60- and 30-min equilibrium time for the modified and native onion skins, respectively. The equilibrium process was well described by the Freundlich isotherm model. The maximum Cd(II) adsorption capacities, from the Langmuir model, are 17.86 mg/g (modified) and 21.28 mg/g (native). The adsorption process followed the mechanism of physisorption. Pseudo second-order rate equation fitted the kinetic data better than the pseudo first-order rate equation for the two adsorbents. Thermodynamic parameters, such as standard free energy change (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°), were calculated for adsorption experimental studies. The results showed that the adsorption of Cd(II) on native/unmodified and modified onion skins was a feasible process and exothermic under the studied conditions. The Cd(II) adsorbed was efficiently desorbed from adsorbent using 0.3 M HCl

Preliminary assessment of the performance of oyster shells and chitin materials as adsorbents in the removal of saxitoxin in aqueous solutions

<p>Abstract</p> <p>Background</p> <p>This study evaluated the adsorption capacity of the natural materials chitin and oyster shell powder (OSP) in the removal of saxitoxin (STX) from water. Simplified reactors of adsorption were prepared containing 200 mg of adsorbents and known concentrations of STX in solutions with pH 5.0 or 7.0, and these solutions were incubated at 25°C with an orbital shaker at 200 RPM. The adsorption isotherms were evaluated within 48 hours, with the results indicating a decrease in STX concentrations in different solutions (2–16 μg/L). The kinetics of adsorption was evaluated at different contact times (0–4320 min) with a decrease in STX concentrations (initial concentration of 10 μg/L). The sampling fractions were filtered through a membrane (0.20 μm) and analyzed with high performance liquid chromatography to quantify the STX concentration remaining in solution.</p> <p>Results</p> <p>Chitin and OSP were found to be efficient adsorbents with a high capacity to remove STX from aqueous solutions within the concentration limits evaluated (> 50% over 18 h). The rate of STX removal for both adsorbents decreased with contact time, which was likely due to the saturation of the adsorbing sites and suggested that the adsorption occurred through ion exchange mechanisms. Our results also indicated that the adsorption equilibrium was influenced by pH and was not favored under acidic conditions.</p> <p>Conclusions</p> <p>The results of this study demonstrate the possibility of using these two materials in the treatment of drinking water contaminated with STX. The characteristics of chitin and OSP were consistent with the classical adsorption models of linear and Freundlich isotherms. Kinetic and thermodynamic evaluations revealed that the adsorption process was spontaneous (ΔG_ads < 0) and favorable and followed pseudo-second-order kinetics.</p