Determination and fractionation of potentially toxic elements in urban particulates

Urban environmental pollution is of increasing concern. There is a need for improved analytical methods to assess risk from potentially toxic elements in urban soils and related material. This thesis focuses on development and application of such methods, notably the modified BCR sequential extraction procedure. The analytes studied were Cr, Cu, Fe, Mn, Ni, Pb and Zn, and quantification was by ICP-AES and ICP-MS. Results obtained by BCR extraction of urban allotment soils were compared with those from aqua regia digestion, 0.05 M EDTA extraction, and the SBET. Correlation analysis and principal component analysis (PCA) grouped analytes into a set mainly of lithogenic origin (Cr, Fe, Mn,Ni) and another of mainly anthropogenic origin (Cu, Pb, Zn). The PCA indicated relationship between amounts of analytes released in step 1 of the sequential extraction and EDTA-extractable analytes, and between results of the SBET method and those obtained with EDTA. The BCR extraction was then miniaturised for application to urban airborne particles. The fractionation pattern was not affected by reducing the sample mass from 1 g to 0.0625 g for particles < 45 μm and 500 - 1000 μm in diameter, but changing the size of vessel used did have an effect. When the miniaturised extraction was applied to test samples presented on filter dynamics measurement system (FDMS) filters a significant Zn blank was found. Despite this, recoveries within 30 % of certified values were obtained when 0.1 g test portion of BCR CRM 701, loaded onto FDMS filters, were extracted. Finally, the chemometric identification of substrates and element distribution (CISED) method was miniaturised and adapted for application to particulate samples on FDMS filters. Four distinct physicochemical components were extracted from BCR 701 using the traditional CISED method, but 11 components when the CRM was loaded onto a filter. The mobilities of the PTE as predicted by the CISED were in good agreements with fractionation patterns obtained using the BCR sequential extraction protocol.Urban environmental pollution is of increasing concern. There is a need for improved analytical methods to assess risk from potentially toxic elements in urban soils and related material. This thesis focuses on development and application of such methods, notably the modified BCR sequential extraction procedure. The analytes studied were Cr, Cu, Fe, Mn, Ni, Pb and Zn, and quantification was by ICP-AES and ICP-MS. Results obtained by BCR extraction of urban allotment soils were compared with those from aqua regia digestion, 0.05 M EDTA extraction, and the SBET. Correlation analysis and principal component analysis (PCA) grouped analytes into a set mainly of lithogenic origin (Cr, Fe, Mn,Ni) and another of mainly anthropogenic origin (Cu, Pb, Zn). The PCA indicated relationship between amounts of analytes released in step 1 of the sequential extraction and EDTA-extractable analytes, and between results of the SBET method and those obtained with EDTA. The BCR extraction was then miniaturised for application to urban airborne particles. The fractionation pattern was not affected by reducing the sample mass from 1 g to 0.0625 g for particles < 45 μm and 500 - 1000 μm in diameter, but changing the size of vessel used did have an effect. When the miniaturised extraction was applied to test samples presented on filter dynamics measurement system (FDMS) filters a significant Zn blank was found. Despite this, recoveries within 30 % of certified values were obtained when 0.1 g test portion of BCR CRM 701, loaded onto FDMS filters, were extracted. Finally, the chemometric identification of substrates and element distribution (CISED) method was miniaturised and adapted for application to particulate samples on FDMS filters. Four distinct physicochemical components were extracted from BCR 701 using the traditional CISED method, but 11 components when the CRM was loaded onto a filter. The mobilities of the PTE as predicted by the CISED were in good agreements with fractionation patterns obtained using the BCR sequential extraction protocol

Studies on biogas production from fruits and vegetable waste

Organic compounds decompose under anaerobic condition to yield biogas. This work presents results of the study on biogas production from fruits and vegetables waste materials and their effect on plants when used as fertilizer (Using digested and undigested sludge). It has been observed that the highest weekly individual production rate is recorded for the cow dung (control) slurry with average production of 1554 cm3, followed by pineapple waste which had 965 cm3 of biogas, then by orange waste which had 612cm3 of biogas, lastly, pumpkin and spinach wastes had 373 cm3 and 269 cm3 respectively. The results obtained shows that difference in the production of biogas to a large extent depends on the nature of the substrate. All the substrates used appeared to be good materials for biogas production and their spent slurries can be used as a source of plant nutrients. Key words: Biogas, Anaerobic digestion, Substrate, Vegetable waste, Cow dun

Fractionation of potentially toxic elements (PTE) in soils irrigated with wastewater using modified BCR sequential extraction procedure

No Abstrac

A Modified Boost-Boost High Gain DC-DC Converter for Photovoltaic (PV) Based Off- Grid Applications

This study presents a single switch non-isolated DC-DC converter good for photovoltaic (PV) applications. The proposed topology was constructed using two classical DC-DC boost converters by arranging them in cascade for providing high voltage gain, low duty-cycle, less stress across the semiconductor devices, less size, and low cost. The operating principle and steady-state analysis of an individual component of the proposed topology in continuous conduction mode (CCM) are discussed and the results obtained improved the ones in literatures. The prototype of 120 V DC output voltage with 9 V DC input voltage is implemented and the result obtained validate the simulated result of the proposed converter. Keywords: DC-DC converter, Photovoltaic (PV), Single switch, High gain, Duty-cycle

Stability assessment of na-doped mesoporous gamma alumina catalyst in transesterification reaction

The leaching of active species was reported to have been the major problem among alkali doped heterogeneous catalysts. Modifying the structure and texture of catalyst support can improve the catalyst’s stability and its activity. In this study, mesoporous gamma alumina, with exellent textural properties, was modified using different amount of NaOH by wet impregnation method, and the catalyst's stability evaluated. The catalysts were characterized using Fourier Transform Infra-Red (FTIR) spectroscopy, N2-sorption (BET), Basic Back Titration, Field Emission Scanning Electron Microscopy (FESEM), and X-Ray Fluorescence (XRF) spectroscopy. There was increased in the number of basic sites and decreased in surface area with increased in the amount of NaOH doping. The FESEM image indicated the incorporation of Na into the alumina after modification. The catalysts were employed in the methanolysis of corn oil, and the biodiesel product analyzed using Proton Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infra-Red/Attenuated Total Reflection (FTIR-ATR) analyses. The reaction conditions for the methanolysis were catalyst loading (5 wt%), oil:methanol molar ratio (1:15), temperature (65 °C) and reaction time (3 h). Highest biodiesel yield of 98.9% was obtained in the present of 15% Na/Al2O3 catalyst. From the leaching test, the catalyst was found to be relatively stable, as only 0.7% of Na2O was leached out. The lixiviation study further buttresses this assertion, with only about 13.5% yield, ruling out any considerable homogeneous contribution in catalytic activity

Comparison of two non-specific flow-through sequential extraction approaches to identify the physico-chemical partitioning of potentially harmful elements in a certified reference material

Two non-specific sequential extraction methods utilising chemometric data processing (chemometric identification of substrates and element distribution, CISED) have been developed and used to determine the physico-chemical partitioning of potentially harmful elements (PHE) in certified reference material BCR CRM 701 (lake sediment). A miniaturized centrifugation method in which the sample was extracted on a filter insert in a polypropylene centrifuging tube, and a quasi-flow through method in which the sample was supported on a TX40 filter in a 47 mm in-line polycarbonate filter holder, gave similar results. The CISED data processing identified nine components. Seven of these were of geochemical origin – two carbonate components, an Al/Fe oxide/hydroxide component, three Fe-dominated components and one Si-dominated component – while the others represented the TX40 filter blank. The overall extraction capabilities of the methods were similar to that of the well-established BCR sequential extraction (Σsteps 1–3). However, whilst the BCR extraction is operationally defined, the CISED provides information on associations between PHE and the geochemical components identified. The flow through CISED procedure has potential applications in investigating the chemical speciation of PHE associated with urban airborne particular matter

Commercial policy and industrialisation in Nigeria, 1963-1978

As a contribution to the continuing debate among trade and development economists as to the role of industrial strategies in the pattern of economic development, this study analyses the experience of one developing country, Nigeria, with an import substitution strategy. The performance of the industrial sector is critically assessed and related to the trade policy adopted. Using published data, the study covers 24 industries and a period of 16 years, beginning 1963 and extending to 1978. An analysis of the structure of protection reveals a considerably high and wide ranging levels of effective protection, in favour of consumer-goods oriented sectors. The relationship between these rates of effective protection on the one hand and import substitution and sectoral growth on the other was examined using various parametric and non-parametric tests of association. The evidence, which is only suggestive in nature, indicates that the structure of protection does play a role, albeit a minimal one, in stimulating industrial growth. Using Input-Output techniques, the employment, foreign exchange and output implications of the present strategy of Import- Substitution and of a hypothetical strategy of export promotion are analysed. There is a general absence of 'key' employment sectors and, paradoxically, an export promotion strategy is found to be less employment generating and more capital using but less foreign exchangeusing than the existing strategy. Although there is a considerable scope for capital-labour substitution in many industries, it was found that the often recommended policy of getting prices 'right' will not be sufficient to bring about an appreciable improvement in the employment situation. The development of factor productivity between 1963 and 1978 for each of the 24 industries was analysed; and three possible determinants of productivity are investigated: capital intensity and technical progress, output growth (the Verdoorn's Law) and trade policy. With regards to the latter, it was found that periods of especially slack productivity growth roughly correspond to those in which there was especially restrictive trade policy as quantified by high erps. The economic efficiency of the manufacturing sector was appraised using the criteria of net social profitability, social rate of return and Domestic Resources Costs (DRCs). Evidence was found in support of the hypothesis that the resource pull of protection to the protected industries is accompanied by higher rates of private, but lower rates of social profitability for the more heavily protected sectors. The overall conclusion of the thesis is that the policies of protection should have been more rationally applied and the IS strategy more rationally executed in line with the country's enunciated objectives

Determination and fractionation of potentially toxic elements (PTE) in soils from an urban allotment

Paper describing the determination and fractionation of potentially toxic elements (PTE) in soils from an urban allotment

Social entrepreneurship as a panacea for insecurity challenges in northern Nigeria

The myriad of problems facing Northern Nigeria, especially high poverty incidence, illiteracy, economic inequality, and conflicts cannot be adequately overcome by the government alone. There is the urgent need for an alternative community intervention mechanism to compliment government’s efforts in confronting social problems on sustainable basis. Today, Social Entrepreneurship is considered critical in achieving vital socio-economic objectives in nations worldwide. Unfortunately, the subject has not received adequate attention in academic and policy discussions in Nigeria.This paper, therefore, is aimed at examining the concept of Social Entrepreneurship in the Nigerian context and also shows how innovative social interventions have assisted in reducing the menace of insecurity problems in Northern Nigeria.The analysis conducted in the paper has benefited extensively from contemporary literature on the subject, observations and interviews with members of three community organisations in northern Nigeria. Accordingly, the paper found that social entrepreneurship has not been fully understood in Nigeria, even though the activities of social groups have tremendously help in reducing the problem of insecurity bedevilling the region. The community organisations observed lacked proper organisation, funding and capacity.With better enlightenment and sensitisation, coupled with improved capacity to generate and manage funding, community organisations will be in better position to augment government’s initiative in restoring peace and security in the northern Nigeria