Browsing by Author "Masalla, Edward Victor"

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    Investigation on phase equilibrium data for seed oil-ethanol- water ternary system
    (University of Dar es Salaam, 1993) Masalla, Edward Victor
    An investigation on phase equilibrium data for seed oil-ethanol-water ternary system was studied. Different oil samples for experiments were collected from local oil industries in different areas of Tanzania, MOPROCO at Morogoro, SHIRECU at Shinyanga, VOIL at Mwanza and from individual palm oil millers at Kigoma. Physical and chemical properties analysed for oil samples showed that crude oils have high amount of FFA, acid value and with exceptional high Ph value for palm oil. Higher values of viscosity were noted for crude oils, difference in refractive index and density is not significant for all oil samples. Oil: ethanol –water mixture rations (wt%) between 50 : 50 and 20 : 80 were applied for UCST data determination. Oil samples with oil : ethanol ratio of 80 : 20 consisting of different values of FFA and pH at ethanol concentrations ranging from 80 : 0% to 99.8% was used for the investigation of water concentration, FFA and pH effects on UCST. Oil: ethanol –water mixture ratio (wt%) between 5: 95 and 80 : 20 were applied for solubility temperature and vapour pressure determinations. For conjugate phase equilibria, bulk solution composition having a constant oil sample of 50% by weight was introduced in the separating funnel containing a mixture of absolute ethanol with water at a ratio of 2: 48 and 10: 40 weight percent respectively. Following phase separation, extract and raffinate phases were obtained. Ethanol concentrations in extract phases were determined by Gas chromatography where peaks for the corresponding ethanol concentration were obtained by subtraction. Working temperature and pressure was 30˚c and 1 atm. respectively. It has been found that, crude oil samples have higher values of acid values, FFA and viscosity compared to refined oil samples. Higher values of FFA and acid values were noted for palm oil sample. Remarkable influence on the variation of oil and waterconcentrations to UCST of seed oil –ethamol-water termary system was observed. UCST for refined oils are approximately 35% higher compared to crude ones, this difference is however, not significant when higher ethanol concentrations are used. FFA and pH were found to have an influence on UCST and solubility data. This dependency was not significant at low and high oil concentrations. Pressure increase was experienced as ethanol concentration decreased. This depicts the optimum range of 95.6 to 100% ethanol concentration for less pressurized solvent extraction equipments. Conjugate phase data reveals low values of equilibrium constant whose equilibrium curves downwards. The results are in agreement with literature, that for the equilibrium constant being less than unit, its equilibrium curves downwards (Phillip Wankat, 1979). Tie-line data results indicate that, data points representing concentration of the phase composition lie on the lie-lines authenticating accuracy of experimental results. Experimental and correlated data analysis by UNIQUAC equation indicate a deviation of about 8.0% for cotton seed oil with low values of FFA and about 2.0% for palm oil with high FFA value. This show that, using ASSAY DATA in Hyprotech process simulator (HYSIM), seed oils with higher values of FFA give less deviation from experimental to analysed correlated data. With respect to experimental results it is concluded that, solvent recycling process should be considered in designing a solvent extraction plant when ethanol is considered as solvent. The consideration being in regard to lower values of phase equilibrium constants which influence excessive use of solvent. However, solvent recycling process will optimize solvent requirements in seed oil extraction. Ethanol concentration ranging between 95.6 to 100% for seed oil extraction process is recommended. The concentration range offers lower vapour pressures, thus limiting the use of pressurized equipments which is ideal for safety reasons. Pilot plant design for seed oil extraction is suggested for further work so as to utilize the already established data in connection with seed oil –ethanol –water ternary system.
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    Process development for citric acid production from sisal waste
    (University of Dar es Salaam, 2003) Masalla, Edward Victor
    Process development for citric acid production from sisal bole juice was taken as a study on wider utilization of a sisal plant. The study based on establishing optimum conditions for inulin hydrolysis and parameters suitable for citric acid production from sisal bole juice by fermentation process. Before hydrolysis, sisal bole juice extract containing inulin was analysed for physical and chemical properties. The juice was found to have physical and chemical properties as indicated in Tables: 3.1 and 3.2 respectively. The mineral composition may vary depending on the soils where the sisal is grown. Sisal bole inulin was chemically hydrolysed using concentrated hydrochloric acid (36%w/w). Hydrolysis temperatures ranged from 60°C — 100°C, reaction time 0 — 60 minutes and pH 0.5 - 3.0. Inulin hydrolysis showed a maximum fructose yield of 116.52g/l at around pH range of 1.0 - 2.0, hydrolysis temperature of 100°C and reaction time of 50 minutes. The fructose yield of 116.52g/l corresponds to 92.5% conversion of sisal bole juice inulin into fructose, which compares well with that of 95% conversion achieved in commercial inulin hydrolysis by Zeolite LZ-M-8. A significant decrease in fructose yield was noted at pH less than 1.0 and pH greater than 2.0. Batch fermentations were carried out aerobically by incubating the cultured media into 300ml flasks for 23 days. Aspergillus Nigger strain was used to evaluate the effects of initial sugar concentration of 60g/l - 150g/l, Nitrogen and Phosphorous sources ranging from 0.1g/l - 3.0g/l and 1.0g/l - 3.0g/l respectively on citric acid yield. Ammonium Sulphate and Potassium di-hydrogen Phosphate were used as nitrogen and phosphorous sources. All experiments showed Aspergillus Nigger strain need high initial sugar concentration ranging from 90g/l - 150g/l in the medium to induce citric acid accumulation. This may be probably due to the dependence of Aspergillus Nigger to literally overfeed themselves before they start releasing the citric acid. In all experiments high yield of citric acid happened around day 17 for all initial sugar concentration of 60g/l - 150g/l, nitrogen and phosphorous supplements ranging from 0.1g/l - 3.0g/l and 1.0g/l - 3.0g/l. Citric acid yield increased with increase in initial sugar concentration from 60g/l - 120g/l where maximum citric acid yield of 83.65g/l was noted at 120g/l and thereafter a decrease in citric acid yield 73.14g/l happened at initial sugar concentration 150g/l, at too high sugar concentrations, the microbes might have difficulties to grow well. Batch B4 had same N/P sources concentration range as for Bl, B2 and B3, with constant initial pH 5.5 and initial sugar concentration of 120g/l. B4 results showed maximum citric acid yield of 80.88g/l at N/P sources concentration of 2.5/1.5(g/l). The N/P sources concentration in B4 were almost similar to Bl (3.0/1.5) with citric acid yield of 83.65g/l. The N/P concentration results indicated that N source to P source ratio by around 1 or 2 lead to better citric acid yield. The effect of pH in all experiments was noted at low initial pH. Bl with initial pH 5.5 showed maximum citric acid yield 83.65g/l as compared to maximum citric acid yield 42.67g/1 at initial pH 2.0 that being 49.0 % decrease in citric acid yield.