Earth Sciences

Permanent URI for this community

http://192.168.18.118:4000/handle/20.500.12661/11

Browse

Now showing 1 - 20 of 242

Pulping sisal fibres: effects of chemical concentration, na2so3/na2co3 ratio and fiber to chemical ratio
(University of Dar es Salaam, 1994) Katima, J.H.Y.; Halfani, M.R.; Ntalikwa, J.W.
This paper reports on pulping of hard fibres extracted from the leaves of agave sisalana using sodium sulphite buffered with sodium carbonate as pulping chemical. The cooking was carried out at I68C for a cooking period of 6 hours, with varying chemical concentration, sodium sulphite to sodium carbonate ratio and fibre to chemical ratio. The results show that both the pulp yield and pulp viscovity decrease with increasing chemical concentration, whereas Kappa number of pulp decreases to a limit of about 16.45. Brightness increases significantly with an increase in the ratio of Na3SO/Na2CO3. The pulp yield obtained indicated the following maximum strength indices: tensile index: 75.60/Nm/gJ, burst index: 6.05/kPa. m2/g/and tear index: 19.30/Nm2/kg). These values are higher than those reported for bleached pine kraft pulp; that is tensile index: 50.52/Nm/g), burst index: 5.77/kPam2/g/and tear index: 18.91/Nm2/kg) with a brightness of 81.0% ISO. These make sisal a promising candidate for non-wood pulping process.
Distribution of organic matter and calcium carbonate in the shelf sediments off Penner River, east coast of India
(Elsevier, 1997) Seetharamaiah, J.; Swamy, A.S.R.
Organic matter and calcium carbonate in the shelf sediments off penner river are mainly controlled by the texture of the sediments. The outer shelf (30-50 m depth) sediments of the southern and northern parts have a higher content of organic matter (1.2 to 2.22%). The sharp differences in organic matter content (varies from 0.8-1.6%) and fine nature of the sediments at the river mouth reveals detrital contribution. A calcium carbonate rich zone (30-40%) associated with coarse sands occurs opposite to penner river mouth (20-50 m depth). The source for high concentration of calcium carbonate in the coarse sands (relict) are molluscan shells, shell fragments and foraminifera indicative of the in situ origin . It is inferred that the calcium carbonate supports that the coarse sands are stillstand deposits admixtured with present conditions.
Electrophoresis of colloidal α-alumina
(2001) Ntalikwa, J. W.; Bryant, R.; Zunzu, J. S. M.
Measurements of the electrophoretic mobility (u E) of particles of colloidal α-alumina were made as a function of pH, electrolyte concentration and electrolyte type (NaCl, NaNO3 and KCl) using two similar instrumental techniques. Significant differences (50% or less) in the values of u E of particles in NaCl were obtained from the two instruments; however, the isoelectric points (IEPs) (the pH at which u E=0), estimated from the two sets of measurements, occurred at 7.5 ± 0.3 and 7.8 ± 0.05 and were not significantly different. The latter estimate corresponds with those for particles in KCl and NaNO3 of 8.05 ± 0.11 and 7.95 ± 0.18, respectively, made using the same instrument and indicate that the IEP was a weak function of electrolyte type. When cations acted as counterions (pH > IEP), the absolute magnitudes and the ranges of u E with electrolyte concentration were found to be significantly less than when anions acted as counterions (IEP > pH). Estimates of the zeta potential (ζ), made using various procedures, showed variations of up to 25% at low ratios of electrical-double-layer thickness (κ −1) to particle radius (a) (κa∼10) and were of a similar scale to differences in u E, but no significant variations (95% confidence) in ζ were obtained at high values (κa∼200).
Provenance study of siliciclastic sediments, Jhura Dome, Kachchh, Gujarat
(Geological Society of India, 2005) Mishra, Diwakar; Tiwari, R. N.
Provenance of the siliciclastic rocks of Patcharn and Chari Formations (Bathonian to Oxfordian) has been ascertained by means of heavy mineral studies. The study shows abundance of transparent heavies like garnet, zircon, tourmaline, staurofite, rutile, hornblende, andalusite, kyanite, anatase and epidote, in decreasing order, and constitute 26.47 per cent of total heavies. The opaque group is represented mainly by goethite and limonite, which constitute 73.45 per cent. The statistical data of heavies reveals that garnet, zircon and tourmaline are more or less uniform throughout the stratigraphic column and constitute 43.92 per cent, 22.27 per cent and 19.99 per cent respectively. The average percentage of staurolite and rutile is 5.40 and 4.52. The percentage of anatase, kyanite, hornblende, anddusite and epidote is very less. On the basis of distribution pattern of heavy minerals in stratigraphic column, heavies are grouped into two distinct assemblages i.e. (i) Garnet-Staurolite-Hornblende-Kyanite-Epidotaes semblage, (ii) prismatic and rounded to subrounded grains of Zircon-Tourmaline-Rutile assemblage. The presence of heavy mineral assemblages in the stratigraphic column reveals that the sediments of Patcham and Chari Formations have been derived mainly from two 1ithologicalIy different Precambrian terrains; one is dominated by metamorphic rocks and the other is igneous (acid and basic), besides a little contribution of sedimentary source. Source rocks were situated close to basin of deposition in the noflheast and east i.e. Aravalli range and north and northwest dominated by Granite-Syenite suite belonging to Nagar-Parkar Massif. The variable ZTR index indicates manifestation of relief and climatic change in the source area.
Lithofacies and depositional dynamics of golden Oolite (Bathonian), Kachchh Mainland, Gujarat (India)
(Elsevier, 2006) Mishra, Diwakar; Tiwari, R.N.
The Golden Oolite Member of the Patcham Formation consisting of 84 m thick alternate sequence of limestones and mudstone are well exposed in the Jhura Dome, Kachchh Mainland, Gujarat. Petrographic study of limestones reveals four types of microfacies: oolitic fossiliferous grainstone (A1); fossiliferous intraclastic grainstone (A2); sandy fossiliferous grainstone (A3); and pebbly fossiliferous grainstone (A4). The microfacies normally form microfacies assemblages with calcareous mudstone (B1) and are stacked vertically in ascending order as A1–A3, A1–B1, A4–B1 and A2–B1. The assemblage (A1–A3) is characterised by interbedding of moderately to thickly bedded, hard and compact, golden coloured oolitic fossiliferous grainstone and sandy fossiliferous grainstone exhibiting small scale low angle planar cross beddings. It contains well preserved bioclast. Assemlage (A1–B1) is distinguished by rhythmic alternations of earthy, concretionary calcareous mudstone and moderately to very thickly bedded golden coloured oolitic fossiliferous grainstone showing ripple bedding, abundant bioclast and reworked intraclasts, whereas assemblage (A4–B1) exhibits rhythmic alternations of bioturbated, earthy, concretionary calcareous mudstone and moderately to thickly bedded pebbly fossiliferous grainstone. Assemblage (A2–B1) is characterised by earthy,bioturbated,calcareous mudstone containing thin uneven beds of fossiliferous intraclastic grainstone having micritic intraclast and microfossils. The study of lithofacies suggests two main depositional processes for the formation of golden oolite: (1) The high energy physical sedimentation from current flows during transgression characterized by irregular to sharp nature of basal contact of each cycle, abundance of well preserved bioclasts and reworked intraclasts and large scale ripple bedding; (2) Settling of fines from suspension during fair-weather period as distinguished by homogenous fine grained interbeds of mudstone in the sequence. The transition of facies from A1–A3 to A2–B1 marks deepening upward event during Bathonian period from shallow inner shelf to calcareous mud dominated outer shelf. The energy condition was very high during deposition of the lower and middle part (A1–A3 and A1–B1 assemblage) whereas low to very low as revealed by abundance of bioturbated calcareous mudstone (B1) with episodic interruption of moderate to high energy storm event depositing A4 (pebbly fossiliferous grainstone) microfacies during the upper part (A4–B1 and A2–B1 assemblage) of the sequence.
Process development of the synthesis of 2, 3-dichlorophenylpiperazine
(Beijing University of Chemical Technology, 2007) Hiji, Morris Frank; Zheng, GuoJun; Yuan, QiPeng
The new pathway for the synthesis of 2, 3-dichlorophenylpiperazine from cheap raw material, 2, 3-dichloroaniline is presented. The hydrogen sulphate salt of 2, 3-dichloroaniline was converted to the corresponding Aryl Iodide in good yield of 81 % by reacting with conc. H2SO4 and NaNO2 to form intermediate diazonium salt, which was further displaced by Kl. The desired product was obtained by reacting Aryl Iodide and piperazine in the presence of CuI as catalyst, proline as ligand, K2C03 as base and dimethyl sulfoxide as solvent with yield of 20 % . The method is simple, utilizes cheap catalyst and ligand, insensitive to moisture; it is easy to separate the product, and can undergo large-scale production.
Microfacies analysis of transgressive condensed sequence: a study from the Oxfordian of Kachchh Basin, Gujarat
(Geological Society of India, 2007) Tiwari, R. N.; Mishra, Diwakar
1-9m thick Dhosa Oolite Member of Chan Formation exposed in Kachchh Mainland, western India, represents a condensed transgressive sequence of the Oxfordtan age. It is composed of hard and compact, fossilifeious, sandy/conglomeratic oolitic limestone interbedded with friable, thinly bedded calcareous siltstone/fine sandstone Field&petrographic studies revealed six microfacies namely, (i)sandy/pebbly ironstone(A1), (ii)conglomeratic fossililerous ironstone (A2), (iii)conglomeratic fossiliferous oolitic packstone(B1), (iv) sandy oolitic packstone (B2), (v) siltstone (C1), (vi) fine grained sandstone (C2). These microfacies are grouped in to three microfacies assemblages namely (i)sandy oolitic Packstone-Siltstone assemblage (B2-C1), (ii) Siltstone-Fine grained sandstone assemblage (C1 - C2) and (iii) conglomeratic fossiliferous oolitic packstone - fine grained sandstone assemblage (C2-B1). The study of microfacies suggests that the deposition of the Dhosa Oolite Member took place in an open marine shallow shelf environment with clear proximal-to'distal trend from southeast to northwest. Two transgressive pulses were responsible for its formation. An earlier slow and frequently interrupted transgression together with subsidence is lecordedby abrupt change in clastic grain size, mixing of two lithologies and abundance of siliciclastics in each microfacies Later, rapid transgression is suggested by the extremely reduced thickness, erosive to irregular contacts, development of intraformatjonal conglomerates, multi phase reworked sediments, an increase in the abundance of carbonates and ammonites and negligible sediment input Lateral vanation in the microfacies and their assemblages together with variable extent of marine mega fauna (ammonites) from southeast to northwest marks the depositional slope ot the basin towards northwest during studied interval. The mixed lithologies in this condensed sequence together with the bioturbated nature of sediments suggest that the rate of sedimentation was extremely slow.
Determination of surface charge density of α-alumina by acid - base titration
(2007) Ntalikwa, Justin W.
The surface charge density (so) of colloidal alpha alumina suspended in various 1:1 electrolytes was measured using acid-base titration. An auto titrator capable of dispensing accurately 25 ± 0.1 μL of titrant was used. The pH and temperature in the titration cell were monitored using single junction electrodes and platinum resistance thermometers, respectively. A constant supply of nitrogen gas in the cell was used to maintain inert conditions. The whole set up was interfaced with a computer for easy data acquisition. It was observed that the material exhibits a point of zero charge (PZC), this occurred at pH of 7.8 ± 0.1, 7.6 ± 0.2, 8.5 ± 0.1, 8.3 ± 0.1 for NaCl, NaNO3, CsCl and CsNO3 systems, respectively. It was also observed that below PZC, so increases with increase in electrolyte concentration (Co) whereas above PZC, so decreases with increase in Co. It was concluded that so of this material is a function of pH and Co and that its polarity can be varied through zero by varying these parameters.
High energy transgressive deposits from the Late Jurassic of Wagad, Eastern Kachchh, India
(Elsevier, 2008) Mishra, Diwakar
The whole sedimentary succession (ca 600 m thick) of Wagad area ranging in age from Callovian to Early Kimmeridgian has been divided in to three Formations namely Washtawa, Kanthkot and Gamdau in ascending order. Prograding Kanthkot Formation was frequently interrupted by transgressions. Field and petrographic investigations revealed that the Kanthkot Formation represents three fossiliferous marker beds corresponding to Transgressive sequence I; Transgressive sequence II and Transgressive sequence III. These transgressive sequences are composed of two lithounits: medium to coarse grained/gritty, graded to massive, sheetlike, fossiliferous calcareous sandstone (storm lag unit I) and fossiliferous mudrocks (swell lag unit II). The thickness of the unit I varies from 5 to 75 cm and contains mostly convexly oriented shell fragments and whole shell of Pelecypods, Cephalopods and Brachiopods. Unit II (5-15 cm) is distinguished by sheetlike, massive or laminated, yellowish colour, soft fossiliferous mudrocks. This unit is intercalated with moderately bioturbated sandy siltstone. Unit I is dominant over Unit II in the sequences. Study suggests that the transgressive units were deposited close to wave base by high energy storm flows followed by low energy marine swells during transgression. The intense storms played a major role in the distribution of siliciclastics and nonclastic materials. Storms are evidenced by the occurrence of two distinctly different types of units (storm lags and swell lags). High energy levels are characterized by sand dominated sequence, abundance of reworked sediment particles, high proportion broken shells with convex up orientation and erosional and sharp nature of basal contacts of units together with well preserved bioclasts. Sudden short term changes from high to low energy during transgression are explained by the occurrence of medium to coarse grained siliciclastics interbedded with moderately bioturbated mudrocks. Moderately bedded individual strata, high content of coarse clastics along with polished granule size quartz and abundance of comminuted shells indicate a significant change in depositional setting, possibly closure approach of the source of terrigenous fraction or source uplift. Synrift sedimentation in the present study is documented by an abundance of coarse clastics and an over all aggradational nature of transgressive sequences.
Sedimentology, sequence stratigraphy and syn-rift model of younger part of Washtawa formation and early part of Kanthkot formation, Wagad, Kachchh basin, Gujarat
(Springer Nature, 2009) Mishra, Diwakar; Biswas, S. K.
The 600 m thick prograding sedimentary succession of Wagad ranging in age from Callovian to Early Kimmeridgian has been divided into three formations namely, Washtawa, Kanthkot and Gamdau. Present study is confined to younger part of the Washtawa Formation and early part of the Kanthkot Formation exposed around Kanthkot, Washtawa, Chitrod and Rapar. The depositional architecture and sedimentation processes of these deposits have been studied applying sequence stratigraphic context. Facies studies have led to identification of five upward stacking facies associations (A, B, C, D, and E) which reflect that deposition was controlled by one single transgressive — regressive cycle. The transgressive deposit is characterized by fining and thinning upward succession of facies consisting of two facies associations: (1) Association A: medium — to coarse-grained calcareous sandstone — mudrocks alternations (2) Association B: fine-grained calcareous sandstone — mudrocks alternations. The top of this association marks maximum flooding surface as identified by bioturbational fabrics and abundance of deep marine fauna (ammonites). Association A is interpreted as high energy transgressive deposit deposited during relative sea level rise. Whereas, facies association B indicates its deposition in low energy marine environment deposited during stand-still period with low supply of sediments. Regressive sedimentary package has been divided into three facies associations consisting of: (1) Association C: gypsiferous mudstone-siltstone/fine sandstone (2) Association D: laminated, medium-grained sandstone — siltstone (3) Association E: well laminated (coarse and fine mode) sandstone interbedded with coarse grained sandstone with trough cross stratification. Regressive succession of facies association C, D and E is interpreted as wave dominated shoreface, foreshore to backshore and dune environment respectively. Sequence stratigraphic concepts have been applied to subdivide these deposits into two genetic sequences: (i) the lower carbonate dominated (25 m) transgressive deposits (TST) include facies association A and B and the upper thick (75m) regressive deposits (HST) include facies association C, D and E. The two sequences are separated by maximum flooding surface (MFS) identified by sudden shift in facies association from B to C. The transgressive facies association A and B represent the sediments deposited during the syn-rift climax followed by regressive sediments comprising association C, D and E deposited during late syn-rift stage.
Combating climate change in Kenya: efforts, challenges and opportunities
(Marsland Press, 2009) Omambia, Anne Nyatichi; Shemsanga, Ceven; Li, Yilian
Increase in emissions of CO2 gas and other greenhouse gases (GHG) such as methane, nitrous oxide, CFC, HCFC and halogens into the atmosphere has led to the overall rise in mean global temperature over the years and the resultant climate change. Key anthropogenic activities responsible include fossil fuel combustion and land -use changes especially tropical deforestation. For developing countries such as Kenya, climate change is a threat to livelihood support systems. Kenya is currently experiencing the effect of climate change especially variation in weather patterns. Prolonged drought and famine has currently left over 10 million people faced with starvation, while floods and resurgence of pests and diseases have been noted in other parts of the country. Widespread poverty, inadequate socio-economic resources and a large climate -dependent agricultural sector makes the country vulnerable to the vagaries of climate change and ill-equipped to adapt to the long-term changes in climate. In spite of these, Kenya has embarked on various measures to mitigate climate change such as adoption of clean development mechanism, reaforestation and spread of green technology. This research focused on Kenya’s effort hitherto in combating climate change, the challenges thereon and opportunities for improvement.
Heavy metal contamination in agricultural soils and water in Dar es Salaam city
(Academic Journals, 2010) Mwegoha, W. J. S.; Kihampa, C.
Heavy metals in soil and water were determined at four points along Msimbazi River valley in Dar es Salaam city, which is popular for vegetable farming. Results indicated that the concentration of chromium in water ranged from (1.414±0.922) to 0.01 mg/L. Maximum and minimum lead concentrations of 0.113 and 0.083 mg/L were detected. The concentration of copper was generally low at all sites, ranging from (0.013±0.005) to (0.016±0.005) mg/L. The concentration of lead in water throughout the river exceeds the WHO (2004) drinking water limit of 0.01 mg/L, ranging from (0.113±0.104) to (0.083±0.059) mg/L. Cadmium concentration at all sampling points was below detection limit of 0.01 mg/L. Soil analysis indicated that the concentrations of heavy metals are highest at the top soil and decreased with depth. Lead had the highest concentration of (22.85±1.502) mg/kg; which did not exceed the TZS (2003) maximum limit of 200 mg/kg for soils. Chromium had maximum and minimum concentrations of (502.33±150.991) and (174.707±168.278) mg/kg, respectively, with most of samples exceeding the TZS (2003) permissible limit of 200 mg/kg. The maximum and minimum concentrations of copper were (21.073±2.881) and (4.513±1.713) mg/kg, respectively, lower than the TZS (2003) permissible limit of 100 mg/kg. Cadmium concentrations at all sampling points were lower than the permissible concentration of 100 mg/kg in soils (TZS, 2003). The presence of heavy metals in soil and water indicates the potential for pollution transfer from these media to the food chain, especially since this valley is popular for vegetable cultivation.
Optimization of biodiesel production from jatropha oil
(Trans Tech Publications Ltd., 2010) Okullo, Aldo; Temu, A.K.; Ntalikwa, J.W.; Ogwok, P.
The most important factors that influence biodiesel production are temperature, molar ratio, catalyst amount, time and degree of agitation. This study investigated the effects of temperature, molar ratio and degree of agitation and their interactions on the yield and purity of biodiesel produced from Jatropha oil. Factorial design and response surface methodology (RSM) were used to predict yield and purity of biodiesel as functions of the three variables. Interactions of all the factors were found to be significant on both yield and purity responses. Temperature and molar ratio main effects were found to be significant on the yield whereas only temperature main effect was significant on the purity of the biodiesel. The optimum conditions of operations were; temperature of 54 oC, molar ratio of methanol to oil of 6:1 and stirring speed of 660 rpm. Using these conditions, biodiesel yield of 95% (wt) was obtained with a purity of 97%. This model can be used to predict the yield and purity of biodiesel from jatropha oil within the ranges of temperature (30 – 60oC), stirring rate (300 -900 rpm), and molar ratio (3 – 9 mol/mol) studied.
The cost of climate change in Tanzania: impacts and adaptation
(Marsland Press, 2010) Shemsanga, Ceven; Omambia, Anne Nyatichi; Gu, Yansheng
In recent years, Tanzania has witnessed a number of climate related disasters namely, flooding, droughts, widespread crop failures, livestock deaths and intensification of climate sensitive diseases among others. Regular climate discussions in the country have often underestimate crucial problems related to climate change like chronic energy crisis and influx of people to urban areas arguably because of failing agriculture in farming areas. This paper has highlighted the fact that the poor, usually with limited resources and who contribute the least to the causes of climate change are the most affected in many ways. In addition, it gives a detailed account of the issues of climate change in Tanzania and explains the effects of climate variability using examples. The effects of climate change in the country are widespread and significantly interfere with agriculture, while at the same time, reducing the ability of the society to deliver services. Indigenous knowledge such as survival skills and coping mechanisms adopted by different societies in Tanzania, have been discussed in the paper. Such coping mechanisms however are overwhelmed by the impacts of climate change on the people. Different institutions including the government have taken some positive steps towards combating climate change; however the efforts done so far are insufficient. In addition, addressing climate change in Tanzania is hindered with inadequate resources, corruption and poor coordination and implementation of combating measures. Generally current climate variability in the nation is an issue of concern for all future plans and must be addressed.
Transesterification reaction kinetics of jatropha oil for biodiesel production
(2011) Okullo, A.; Temu, A. K.; Ntalikwa, J. W.
Biodiesel, defined as the monoalkyl esters of vegetable oils and animal fats, is becoming prominent among alternatives to conventional petro-diesel due to economic, environmental and social factors. Transesterification is the most preferred method of biodiesel production. Knowledge of transesterification reaction kinetic enables prediction of the extent of the chemical reaction (or the conversion) at any time under particular conditions. It is also essential in the optimization of operating conditions in industrial applications and in the design of reactors for biodiesel production. In this study, transesterification of jatropha oil with methanol was carried out in a well mixed reactor at different agitation speeds (600-900 rpm) and temperatures (35-65 oC) using sodium hydroxide as a catalyst. The methanol to oil molar ratio of 6:1 was used and catalyst loading was 0.5% weight of oil. Mass transfer controlled state was assumed to be minimal using the above agitation speeds. A second order kinetic model was used to determine the reaction rate constants. The goodness of fit predicting the moles of methyl ester in the reaction products was determined by correlation coefficient (R2) and least square curve fit. The forward reactions were the most important as revealed by the rate constants.
Physico-chemical properties of biodiesel from jatropha and castor oils
(Gazi University, 2012) Okullo, Aldo; Temu, A. K.; Ogwok, P.; Ntalikwa, J. W.
Biodiesel is becoming prominent among the alternatives to conventional petro-diesel due to economic, environmental and social factors. The quality of biodiesel is influenced by the nature of feedstock and the production processes employed. High amounts of free fatty acids (FFA) in the feedstock are known to be detrimental to the quality of biodiesel. In addition, oils with compounds containing hydroxyl groups possess high viscosity due to hydrogen bonding. American Standards and Testing Materials, (ASTM D 6751) recommends FFA content of not more than 0.5% in biodiesel and a viscosity of less than 6 mm2/s. The physico-chemical properties of jatropha and castor oils were assessed for their potential in biodiesel. The properties of jatropha and castor oils were compared with those of palm from literature while that of biodiesel were compared with petro-diesel, ASTM and European Standards (EN14214). Results showed that high amounts of FFA in oils produced low quality biodiesel while neutralized oils with low amounts of FFA produced high quality biodiesel. The quality of biodiesel from jatropha and castor oils was improved greatly by neutralising the crude oils
Climate change impacts, vulnerability, and adaptation in East Africa (EA) and South America (SA)
(Springer Nature, 2012) Omambia, Anne Nyatichi; Shemsanga, Ceven; Hernandez, Ivonne Andrea Sanchez
In recent decades, global climate change has continued to cause devastating impacts to various places on Earth. Geographic and socioeconomic characteristics in East Africa (EA) and South America (SA) make the regions among the most vulnerable to the current temperature variations attracting several studies with wider implications. Presently, in these two regions, remarkable evidence of climate change includes repeated droughts and increase in dry lands affecting water and food availability for humans, livestock, and wildlife (EA), intensification of climate-sensitive diseases, sea level rise, fast retreat of glaciers on Mount Kilimanjaro in Tanzania, Mount Kenya in Kenya, and Andeans Mountains of South America, change in the rainfall patterns in the Amazon forests and in the whole of EA, and increasing of the frequency and intensity of the El Niño and La Niña phenomenon in the South Pacific that affect both EA and SA, among others. Although these two regions are not major contributors of greenhouse gases (GHGs), the poor conservation of strategic ecosystems through deforestation of the Amazon forests in SA and various forests in EA coupled with intensification of agriculture, land degradation, rapid rates of urbanization and industrialization all driven by rapid population increase are putting a strain on valuable natural resources whose conservation would be critical in mitigating climate change. Adaptation measures have been constrained by climate change impacts. In both regions, poverty is widespread and climate change impacts have jeopardized most poverty alleviation initiatives including realization of some of the Millennium Development Goals (MDGs). Moreover, both regions have a strong dependency on rain-fed agriculture for economic development with hydroelectricity and biomass as main sources of energy. Consequently, adaptation measures are required for all the sectors, but especially in agriculture, health, and energy where the loss of soil productivity, increasing spread of climate-sensitive diseases, reduction of water and energy source supply are already threatening the social and economic security of both regions. Both regions have a wealth of indigenous knowledge and coping mechanisms of various local communities that should be incorporated into conventional adaptation measures of climate change. This chapter describes the main climate change impacts in EA and SA, vulnerabilities thereon, and adaptation measures that offer an opportunity to the two regions to develop in a sustainable way.
Biomass gasification using a horizontal entrained-flow gasifier and catalytic processing of the product gas
(Cardiff Insitute of EnergyCardiff University, 2012) Legonda, Isack Amos
A novel study on biomass-air gasification using a horizontal entrained-flow gasifier and catalytic processing of the product gas has been conducted. The study was designed to investigate the effect of catalyst loading on the product gas. The use of a horizontal entrained-flow gasifier reactor was used toassess the effect of the gasifier reactor orientation on the gasification process. Both experimental and computational fluid dynamics (CFD) approaches were employed. The gasification tests were conducted at 800oC and equivalence ratio of 0.23 while the product gas was catalysed at 350-400oC and a gas hourly space velocity (GHSV) of 8000h-1. Preparation and characterisation of wood powder and catalysts were performed using classical methods. Moreover, the syngas and tar composition were analysed using a gas chromatograph (GC) and GC-mass spectrometer (GC-MS) respectively. The research findings showed that maximum fuel conversion and cold gas efficiency using a horizontal entrained-flow gasifier were 99% and 70%respectively. The gasifier length can also be reduced from the common 1000-2000 mm to 500 mm. The catalysis study showedthat pumice and kaolin have limited catalytic effect on the product gas.However,doping with CeO2, ZrO2, CuO and NiO improved the syngas heating value, coking resistance and tar conversion. A notable increase in syngas LHVwas achievedusing ceria doped pumice (8.97MJ/Nm3) and copper doped pumice (8.66MJ/Nm3) compared to6.67 MJ/Nm3of non-catalytic test. For the tested catalysts, CeO2doped pumice exhibited highest coking resistance. Furthermore, catalytic tar conversion was mainly through cracking and partial oxidation reactions. The lowesttar yield was found to be 3.55g/Nm3using kaolin-ceria-zirconia catalystcompared to 14.92 g/Nm3of non-catalytic gasification. Tar reduction usinguntreated pumice was through adsorption and ranged4-6 g/Nm3.In general, the results of this study suggest that there exist a sensitivity to the gasifier orientation on the overall gasification process. It has also shown that metal oxides have both beneficial and detrimental effects of syngas composition. Although syngas heating value increased with increasing catalyst loading, H2showed a decreasing trend highlighting that further catalyst modification is required. Furthermore, pumice and kaolin can be utilised as catalyst support in the gasification technology. However, further experimental investigation on doping various catalytic metals and testing at different operating conditions are hereby proposed.
Chemical water quality of bottled drinking water brands marketed in Mwanza City, Tanzania
(Indian Academy of Sciences, 2012) Mihayo, I.Z; Mkoma, S.L
Water is a useful resource for domestic, industrial and agricultural purposes and its importance to man cannot be overemphasized due to its essentiality in body metabolism and proper functioning of cells. The present study was carried out to determine the physico-chemical quality of bottled drinking water brands available in retail shops in Mwanza city (Tanzania), and compare with drinking water standards. The results show that water type for different bottled water brands when classified according to TDS ranged from very low concentrations (brands A and B) to low concentrations (brands C, D, E, and F). Based on the classification criteria of total hardness, most brands were considered to have soft water except for brand E which had moderately hard water. The dominant component to all bottled water brands was SO42− accounted 48% to 90% of the total major ions, whereas Cl− accounted for 8% to 25%. Somewhat high contributions up to 20% was observed for Ca2+, while Mg2+ was below 9%, and Fe2+ and NO3− were below 6%. Brand D has exceptionally high levels for Cl−, NO3−, and Mg2+ ions. When compared with Tanzania Bureau of Standards (TBS) and World Health Organization (WHO) guidelines for drinking water, analysed parameters in all brands were within TBS and WHO limit values for drinking water. The study therefore concludes that the analysed bottled water brands are safe for human consumption. However, it recommends other water quality parameters such as microbiological and heavy metal be studied in future.
Gas chromatographic determination of glycerol and triglycerides in biodiesel from jatropha and castor vegetable oils
(Trans Tech Publications Ltd., 2013) Okullo, Apita, Aldo; Ogwok, P; Temu, Abraham K.; Ntalikwa, J.W.
Monoacylglycerols and diacylglycerols are intermediate compounds in biodiesel which result from incomplete transesterification reaction during biodiesel production. Traces of free glycerine and partially reacted triacylglycerols are also found in biodiesel. These contaminants cause serious operational problems in engines, such as engine deposits, filter plugging, and emissions of hazardous gasses. Increased levels of these contaminants in biodiesel compromise quality which is vital for commercialisation of this product. In this work, levels of free glycerine and total glycerine in jatropha methyl ester (JME) and castor methyl ester (CME) were determined using gas chromatography (GC) equipment. Amounts of free and total glycerine in JME and CME were generally high compared to the ASTM D6751 and EN14214 recommended values. Free glycerine from JME was 0.1% wt compared to 0.02% wt (ASTM D6751) and 0.01% wt (EN14214) values whereas the total glycerine from JME was 2.96% wt compared to 0.24 %wt (ASTM D6751) and 0.21% wt (EN14214). These discrepancies could have resulted from insufficient purification of the product and incomplete conversion or due to the high temperature associated with GC analysis that might have caused pyrolysis or thermal degradation of certain lipid components. Castor methyl ester free glycerine was 0.14% wt while total glycerine was 13.21% wt. This can still be explained by the same reasons given for JME. Thermal decomposition of lipid components in a GC could have interfered with the summative mass closure calculations that were done to determine the total composition of the biomass.

Browse

Browsing Earth Sciences by Issue Date

Results Per Page

Sort Options