Browsing by Author "Ilomo, Ophery Ozias"

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    Preparation and characterization of polymeric materials from Tanzanian cashewnut shell liquid.
    (University of Dar es Salaam, 2001) Ilomo, Ophery Ozias
    Polymeric materials are now becoming inseparable from human beings. These materials are increasingly being made for use in various industrial and domestic activities. In this study Micron-Sized Polymeric Particles (MSPP) were prepared by a condensation reaction between Cashew Nut Shell Liquid (CNSL) and formaldehyde in an aqueous medium at 60°C through an emulsion polycondensation method. Sodium Lauryl Sulfate (NaLS) was used as a stabilizer and an emulsifier. Polymerization rate and yield were both found to increase as pH of the reaction mixture increases or as emulsifier concentration increases. The MSPP were found to have sizes ranging from 0.1 to 4.4 um. The sizes were found to decrease as the emulsifier concentration increase or increase as NaOH concentration increase. The latter reduced the effective concentration of the emulsifier. These particles appeared to be physically stable in alkalis, mineral acids and organic solvents. The surfaces of MSPP were chemically modified by reaction with monochloroacetic acid to produce an Ion Exchange Resin (IER). Cation Exchange Capacity (CEC) of IER was found to vary from 3.8 to 5.4 meq/g depending on both the method used to determine CEC and the size of the particles. Cation exchange of both modified (IER) and unmodified MSPP were investigated and the former was found to exchange up to 86.36 mg of calcium ion per gram of the polymer, whereas the latter could exchange up to about 6.57 mg of calcium ion per gram of the polymer at 30°C. On the other hand the pKa of the IER prepared was found to be 6.2. Generally, these results showed that the IER prepared are useful and suitable for ion exchange applications.
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    Temporal and spatial variation in stable isotope and heavy metals in sediment and coral reef of the coastal marine areas of Tanzania
    (University of Dar es Salaam, 2017) Ilomo, Ophery Ozias
    Trace metals concentrations, carbon and total nitrogen contents, coral growth rates, CaCO3 content, Sr/Ca ratio, δ13C, δ15N and δ18O of both the bulk sediment and coral cores retrieved mainly between the land and the fringing reefs off Dar es Salaam City and off Zanzibar Town were used to (i) assess levels of contamination; (ii) document temporal and spatial variation in anthropogenic perturbation of the marine environment and (iii) reconstruct sea surface temperature (SST) on different timescales. The results showed metal concentrations in both sediments and coral samples were significantly higher off Dar es Salaam as compared to Zanzibar sites (P<0.01). The elevated degree of heavy metals contamination (Cd>2) and enrichment (EF>1) suggesting an increase in anthropogenic pollution resulting from discharge of untreated industrial and domestic effluents. The δ13C and δ18O averaging 1.18‰ and 1.79 ‰ respectively were more enriched in 13C and 18O, suggesting that the sediment contains carbonate originating mainly from marine shallow waters. Lower enrichment of 15N (average 1.96 ‰) were probably due to low primary productivity and inflow of terrestrial sources in the Zanzibar channel. The Porites coral growth rate was between 7 to 12 mm yr-1 and SST variability was observable. The lowest SST was in the year 1710 probably representing the little ice age. The reconstructed and recent instrumental SST data are positively correlated (r=0.7, P<0.01). Remarkable temporal increase in N-content in corals (0.01 to 0.30%) and the elevated δ15N at Tanga (7.04‰) and Dar es Salaam (9.78‰) might be due to anthropogenic activities. Authorities are advised to establish a strict industrial and domestic effluents management framework to municipalities and industries to prevent further pollution.