Modern Scientific Press

ABSTRACT: The south bank of River Benue usually cultivated both in the wet and dry seasons is characterized by anthropogenic activities such as wastes disposal, burning of animal skin and remains and heavy traffic on the bridge. Run-off water from rains could wash heavy metals amongst other contaminants into the river or leave them as sediments on the farm soils and these could be taken up by the vegetables grown on them. This gave impetus to investigating the concentrations of Cd, Cr, Cu, Ni and Pb in Telfairia occidentalis (fluted pumpkin), Talinium triangulare (water leaf) and Amaranthus hybridus (spinach) cultivated along the south bank of River Benue in Makurdi and their farm soils using atomic absorption spectroscopy. The mean concentrations (mg/kg) of Cd, Cr, Cu, Ni and Pb in T. occidentalis were 0.0043, 0.0268, 0.2501, 0.2047 and 0.1868; T. triangulare: 0.0058, 0.0090, 0.0902, 0.2207 and 0.1641 and A. hybridus: 0.0078, 0.0172, 0.0863, 0.0714 and 0.2441, respectively. The mean concentration of the heavy metals in the farm soils ranged between 0.0146 mg/kg cadmium to 4.4992 mg/kg lead in T. triangulare and A. hybridus farm soils respectively. The concentrations of the metals in the vegetables and farm soils showed strong positive correlations. The soil-plant transfer factors of the heavy metals revealed very high absorption of Ni (2.094) and Cu (2.601) by T. triangulare and A. hybridus, respectively. T. occidentalis recorded high absorption of Ni (0.758) and Pb (0.646). Generally, the concentrations of the heavy metals in the soils and vegetable were below the permissible limits set by European Union, WHO/FAO, and Nigerian Agency for Food and Drug Administration and Control (NAFDAC).

ABSTRACT: The present investigation deals with the interesterification, using immobilized lipase of marine microalga Chlorella salina oil for producing biodiesel. Lipase was extracted from a marine bacterial isolate, Bacillus sp.S23 (KF2206559.1), confirmed by 16S rRNA sequencing. The enzyme was encapsulated in sodium alginate beads, which is cost effective and environment friendly. The study was carried out for the effect of enzyme loading, temperature, molar ratio, water, reaction time and agitation. The optimum condition required for the process to occur were: 1.5g enzyme bead, 1:12 molar ratio of oil to methyl acetate, temperature 35oC, 8% water, 60 h reaction time and 250 rpm agitation speed. The maximum biodiesel conversion efficiency was found to be 92.34%. Reusability of immobilized enzyme was evaluated by 10 cycles of repeated batch cycles, finding they were stable and there was no loss of lipase activity in the presence of methyl acetate as acyl acceptor. The biodiesel composition was analysed using GC-MS. This work indicates that the immobilized enzyme could interesterify microalgal oil in an efficient manner, also being a cost effective process.

ABSTRACT: Solar energy is currently represents the most abundant inexhaustible, non- polluting and free energy resources that could be used economically to supply man’s increasing energy demands. This paper presents the experimental performance study of a parabolic trough concentrator, which was constructed and investigated under climatic conditions of Dundaye at Sokoto Energy Research Center, Usmanu Danfodiyo University Sokoto, Nigeria. The collector was constructed using locally available materials with design parameters as: Focal distance of 0.15m, 1.82m length of the collector and depth of the collector as 0.33m.The experimental test conducted to evaluate the collector showed that the maximum outlet water temperature attained was 110^oC, which is fairly acceptable, considering that it was an attempt to use local materials. Even though it encountered some problems such as inaccuracy in tracking the sun since it is manually tracked. However, the results obtained have shown that the temperature achieved is almost equivalent to the temperature at which the matter changes from liquid (water) to gas (steam). In this case it can be said that when appropriate tracking mechanism is used, this collector could be used for steam generation which can turns steam turbine for electricity generation.

ABSTRACT: The foremost interest in this research is to assay the potential of the leaves and stems of Ricinus communis in generation of Biogas under anaerobic condition. Three digesters were studied which include Ricinus communis leaves, Ricinus communis stem and Cowdung (reference sample). The slurries in each digester contained 40 g sample and 800 ml of water (i.e. 0.05gcm-3 slurry concentrations). Physicochemical characterization of the digesters for percentage moisture contents (%MC), ash content (%AC), volatile matter (%VM), total solid (%TS), and carbon contents (%CC) were also assayed. The results of the pH varied from 6.8 to 7.1, the temperature fluctuated from 27^oC to 33^oC. The retention time was 84 days (i.e. 12 weeks). The total volumes of biogas generated were 7.92, 6.13 and 4.38 Litres for Cowdung, Ricinus communis and Ricinus communis stem respectively. The biogas production capacity order for the three substrates during the 12 weeks period is Cowdung > Ricinus communis leaves > Ricinus communis stem. Physicochemical analysis on some parameters that affect the Biogas generation process was also conducted.