Analysis of sediment samples for some trace and major metals from Okaba coal mine in Kogi State, Nigeria by energy-dispersive x-ray fluorescence spectrometry: Effect of seasonal variations on the concentrations of these metals

Coal sediment samples from Okaba coal mine in Kogi State, Nigeria, were subjected to analysis for some metallic and non-metallic compositions. Of 35 elements determined by energy-dispersive X-ray fluorescence  spectrometry, a number of anomalously high levels were recorded. Elements determined are Al, Si, P, S, K, Ca, Ti, Cr, Mn, V, Fe, Ni, Cu, Zn, Rb, Zr, Ru, Ba, Sr, Y, Se, Os, Bi, Sb, Pb, Mg, Na, Se, Br, As, Cl, Au, Nb, Hg and W. Most of the known or potential metal contaminants are included in this list. The extent of contamination of sediments by metals analysed is greatest for Fe and then in decreasing order Al, K, Ti, Ru, Zr, Sb, Pb, Ba, Cu, V, Mn, Sr, Cr, Y, Bi, Rb, As, Au, Sc and Os. Results are presented. It was observed from seasonal variations that flooding and leaching contributed to the increase in the concentrations of the metals studied at the downstream. Metals such as Mg, Na, Se, Os, Bi, Nb, Hg and W were not detected at all levels. Thus the coal mine contributed greatly to these concentrations in all the sediment samples. Seasonal variations play an important role in the concentrations of the metals studied. This was evident at the downstream part of the sediment samples were elevated concentrations were observed.Keywords: coal, trace metals, ED-XRF, sediments, seasonal variation

Trace and major metal abundances in the shale and coal of various seams at Okaba coal mine, Kogi State, Nigeria

The distribution of a number of trace and major elements in the shale and coal of differing seams in Okaba, Kogi State, Nigeria, was studied using energy dispersive x-ray fluorescence spectrometer. The study was necessary to compare the quality of Okaba coal to world standards of coal quality. Major elements of Al, K, Ca and Fe showed concentration ranges of 5.93±2.49 – 8.42±0.003 mg/g, 0.18±0.46 – 2.16±0.0 mg/g, 0.53±0.41 – 2.23±0.35 mg/g and 6.05±0.004 – 18.28±1.2 mg/g respectively. The mean concentrations are 7.24mg/g (Al), 1.25 mg/g (K), 0.91 mg/g (Ca) and 11.86 mg/g (Fe). These values are clearly above the recommended concentrations in coal quality standards and for air emission standards by the World health organization. Trace metals of Ti, Cr, Mn, V, Ni and Cu showed concentration range of 0.84±0.007 – 2.98±0.007 mg/g , 0.03±0.0 – 0.12±0.025 mg/g, 0.02±0.11 – 0.30±0.02 mg/g, 0.02±0.44 – 0.2±0.05 mg/g, 0.01±0.075 – 0.12±0.001 mg/g and 0.03±0.02 – 0.62±0.001 mg/g respectively. These results indicate that Okaba coal and shale is enriched in the major elements analysed in comparison to worldwide averages of coal while the trace elements with exception of Ti are below the coal quality standards. Correlations between the various metals were also established. The S content correlated inversely well with the K content of both the shale and coal. Expectedly, the percentage Si content was high in the shale1  (26.70%) and shale2 (26.38%), while the lowest concentration was  recorded at Okaba coal seam 5 (6.58%). The absence of Cl, Br, Na, and Mg in the samples clearly indicates the extent of surface leaching on the study area. This is evident by the various mountainous depressions in the study area.Keywords: Trace metals, EDXRF, coal, shale, major metals, seam

Biosorptive removal of cobalt (II) ions from aqueous solution by Amaranthus hydridus L. stalk wastes

The objective of this study was to investigate the possibility of using Amaranthus hybridus L. stalk as an alternative to high cost commercial adsorbent materials for the removal of Co (II) from aqueous solution. The experiment was carried out by batch method at 33°C. The influence of pH, contact time and initial metal ion concentration were evaluated. It was observed that pH had marked effect on the Co (II) uptake. The optimum contact time between the adsorbent and the adsorbate was found to be 90 min. Maximum adsorption was obtained at pH 5. Freundlich models were used to correlate equilibrium data on sorption of Co (II) ion at 33°C and pH 5, and different coefficients were calculated. The data generated, fitted well with Freundlich adsorption model. The biomass was successfully used for removal of cobalt (II) ion from synthetic aqueous solution and the technique appears industrially applicable and viable.Key words: Biosorption, cobalt, aqueous solution, Amaranthus hydrides

Chemical composition of Annona senegalensis from Nupe land, Nigeria

The proximate, mineral composition, amino acids content and phytochemical screening of Anona senegalensis seed vegetable collected from different farm site in Bida town, Niger State, Nigeria, were carried out using standard methods of food analysis. The results of the proximate composition show that the sample contained 12.20% moisture, 12.10% ash, 24.00% fat, 17.60% crude fibre, 8.80% crude protein and 25.3% of carbohydrate, respectively. Mineral composition in mg/g from the results revealed that calcium, potassium, magnesium, zinc, iron, copper, manganese, lead and chromium values are 1.35, 0.47, 0.24, 0.48, 1.80, 0.29, 0.13, 1.10 and < 0.1, respectively. The phytochemical screening indicates the presence of saponins, steroid, flavonoid and glycoside in the sample. The results revealedhigh values of amino acid content in the sample and the values are comparable to Food and Agricultural Organization/ World Health Organization (FAO/WHO) standard

Speciation of some selected heavy metals in coal bottom ash from Okaba Coal, Ankpa, Nigeria

Speciation of coal cotton ash from Okaba in Kogi State Nigeria was carried out using flame atomic absorption spectrometry. Results of this research showed that the elements studied (Cr, Fe, Cu, Ni, Pb, Cd and Zn) were all observed in at least three fractions of the sequential extraction procedure. Pb showed more presence in the exchangeable fraction (80±0.03 µg/g) which is a serious problem to plants and human due to weathering activities in the soil. Most of the elements with high concentration in the residual fractions were found to be thermally stable and of low volatility (Cu and Zn). Chromium occurred mostly as a reducible fraction (80±0.02 µg/g) while Fe occurred mostly as bound to carbonate species. Cadmium was generally low in all the fractions analysed. This trend may be attributed to high volatility of Cd species. Similarly, Ni had a distribution in all the fractions with the highest in the reducible fraction (39±0.01 µg/g) and lowest in the carbonate bound fraction (24 ±0.01 µg/g). The exchangeable fraction of the elements studied is consistent with previous studies of coal bottom ash speciation. The ash matrix may also have contributed to a significant rise in the concentration of Ni at the exchangeable fraction thereby leading to significant variations in metal concentration over the ash particle.Keywords: Speciation, heavy metals, coal, Ankpa, bottom ash

Bioavailability of metals in some selected plants grown on an abandoned coal mine overburden using energy dispersive X-ray fluorescence technique

This study focuses on the bioavailability of some metals in Mangifera indica, Parkia biglobosa, Proposis africanus, Anacardium occidentale and Manihot esculenta plants grown on an abandoned coal mine overburden. The analytical technique used in this study is energy dispersive x-ray fluorescence spectrometry. The results indicate that the plants have the tendency to bioaccumulate the metals studied in this order: Proposis africanus > Anacardium occidentale > Manihot esculenta > Parkia biglobosa > Mangifera indica. The various concentrations of the observed metals in the plants grown in overburden soil were considerably lower than those observed from the control soil. This however was attributed to the increase in the sorption of metals with increasing pH. The concentration of metals in the overburden plants ranged from 0.60 – 18.00 mg/kg (Ti); 1.03 – 1.78 mg/kg (Cr); 5.81 – 67.27 mg/kg (Mn); 6.03 – 51.17 mg/kg (Fe); 0.30 – 2.91 mg/kg (Ni); 2.32 – 15.66 mg/kg (Cu); 0.54 – 6.15 mg/kg (Re); 3.50 – 8.90 mg/kg (Au); 0.16 – 3.69 mg/kg (Zn); 0.69 – 3.55 mg/kg (Sr); 14.04 – 111.57 mg/kg (Ru); 0.67 – 2.84 mg/kg (Y) and 1.79 – 15.22 mg/kg (Ba). For the control plants 50 Km from mine site overburden, the observed concentration ranged from 2.34 – 14.40 mg/Kg (Ti); 1.16 – 2.56 mg/kg (Cr); 4.19 – 54.95 mg/kg (Mn); 15.05 – 101.50 mg/kg (Fe); 0.79 – 4.56 mg/kg (Ni); 5.99 – 24.45 mg/kg (Cu); 2.77 – 10.77 mg/kg (Re); 4.70 – 12.00 mg/kg (Au); 0.08 – 49.08 mg/kg (Zn); 1.10 – 5.08 mg/kg (Sr); 41.37 – 210.24 mg/kg (Ru); 1.18 – 4.10 mg/kg (Y) and 0.29 – 7.52 mg/kg (Ba). The values obtained are far above World Health Organization tolerable daily intake and are attributed to the nature of the soil in the mineral rich coal basin.Keywords: Biosorption, bioremediation, absorption, heavy metals, overburde