School of Chemical and Bio Engineering

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    A Study on The Flour Properties and Qualities of Wheat-Based Biscuits Supplemented with Faba-Bean and Cassava Flour
    (Addis Ababa University, 2023-09) Gebremedhn Brhane; Shmeles Shumi (PhD)
    Faba beans and other legumes are significant due to their high nutritional value. The goal of this study is to investigate on the flour properties and qualities of wheat-based biscuits supplemented with faba-bean and cassava flour. The study examined the proximate composition of both (composite flour and biscuit flour), rheological, and functional properties. Besides mineral content, total energy, gluten content, texture, color attribute, and sensory evaluation have been studied. The formulation for composite flour was developed using a D-optimal mixture design ratio applying Design-Expert®, version 13. Accordingly, 16 composite flour samples were developed (T1, T2……. T16 and control sample) and evaluated using the standard method. The gluten content of wheat flour was significantly different from the whole formulated composite flour and also the samples were significantly different from each other at (p<0.05). The proximate composition shows that the crude protein content of faba-bean flour (23.13±0.00%) is two times more than that of wheat flour (11.75±0.00%) and eight times more than that of cassava flour (2.9±0.02%), respectively. Whereas, composite flours show lower water absorption capacity and higher oil absorption capacity and water solubility than wheat flour. The result showed that the pasting temperature range was 72.55 to 76.70 °C compared with the pasting temperature of the control sample (89.65 °C). Moreover, biscuit developed from 40.5% wheat flour, 40% cassava flour and 19.5% faba-bean flour biscuit looked almost similar to the wheat flour biscuit in all aspect with overall acceptability of 8.05±0.64. In this study the 40.5% wheat flour, 40% cassava flour and 19.5% faba-bean flour biscuit was found to be the most acceptable biscuit and had high crude protein, crude fiber and low gluten content. On the other hand, adding faba-bean flour to wheat-cassava flour positively affects the physical, chemical, color attribute, texture, alkaline water retention capacity, staling rate and sensory characteristics of the biscuits.
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    Accelerated Shelf-life Prediction and Quality Characterization of Edible Cotton, Peanut and Soybean Seed Oils Produced in Ethiopia
    (Addis Ababa University, 2017-10-23) Addisu, Alemayhu; Shimelis, Admassu (Assoc.Prof.)
    Edible oils are regarded as an important component of the diet because they are source of energy, essential fatty acids, and also provide characteristic flavors and textures to foods. The purpose of this research study was to determine the qualities of edible cottonseed, peanut and soybean oils processed in Ethiopia and predict their shelf-life using ASTM. The AOAC method of Analysis was employed in the determination of the physical and chemical characteristics of the oils. The result obtained for edible soybean, peanut and cottonseed oils, respectively were; specific gravity at 20/20OC: 0.929, 0.943 and 0.922, refractive index at 20OC: 1.48850, 1.48508, and 1.48565, photometric color index: 5.262, 15.908 and 216.316, insoluble impurities: 0.001, 0.004, and 0.013% (w/w), moisture content: 0.210, 0.219 and 0.220% (w/w), peroxide value: 1.299, 2.398, and 3.396meq O2/kg of oil, iodine value: 136.740, 97.536 and 101.112grams of iodine absorbed/100g oil, Saponification value: 210.345, 210.779 and 208.411mgKOH/g, unsaponifiable matters: 0.169, 0.069 and 0.383% (w/w), and acid value: 0.420, 0.630 and 0.561mgKOH/g. Fatty acid profiles were also determined by GC-MS as methyl esters. The results showed that the predominant fatty acid in edible soybean and cottonseed oils was linoleic acid 42.807 and 41.587%, respectively while oleic acid (46.252%) was major fatty acid in edible peanut oil. The shelf-life of edible oils was tested applying ASTM. The oils were subjected to three different elevated temperatures: 35, 45 and 55OC in acceleration chamber and hydrogen peroxides formation were monitored for six successive weeks. The evaluation was performed graphically (fitting of experimental data to a linear equation) after completion of the experiments. Accordingly, the model that best fitted the experimental data corresponds to a zero order kinetic model for all edible oil investigated. Arrhenius relation was applied to model that effect of temperature on the rate constant of peroxide formation. Combining the kinetic model identified and the rate constant model equation, a general shelf-life model equation that could help to predict the shelf-life of oils studied at any temperature was developed. Employing predictive model developed, the shelf-life of the domestic edible oils was determined at room temperature (25OC) and amounts 36.9 weeks for soybean oil, 42.1 weeks for peanut oil and 37.8 weeks for cottonseed oil. The result obtained for most physicochemical quality parameters of the edible oils considered were within the standard range indicated by Ethiopia Standard Agency. From fatty acid profile analysis it can be concluded that edible soybean, peanut and cottonseed oils are an excellent source of essential fatty acid omega-6 (linoleic acid) and omega-9 (oleic acid). Comparatively edible peanut oil had longer shelf-life than edible soybean and cottonseed oils. The shelf-life of properly refined edible oils is typically 12 – 18 months at ambient temperature. From shelf-life assessment, all edible oils investigated scored lower shelf-life. So, to minimize the oxidation of edible oils and maximize the shelf-life, it is recommended to use: antioxidants, sequestering agents and selection of appropriate packaging material (colored glass bottle). Besides, FFAs are more susceptible to oxidation than the glycerol esters of these fatty acids. Therefore, any increase in the acidity of the oil must be absolutely avoided during refining of the oil.
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    AComparative Study on Selected Tomato Varieties for Manufacturing Paste
    (Addis Ababa University, 2016-06) Abdu, Jemal; Edecha, Mekonen
    The favorable climatic condition, vast irrigation sources, abundant labor and other factors in Ethiopia are viable for the production and processing of tomato fruits, generally for fruits and vegetables. Tomato and tomato-based products are important sources of many established nutrients that have health benefits. This study aimed to compare the performance of selected local and foreign tomato varieties for manufacturing paste. The pastes were produced from three raw tomato varieties namely; Galilea (GL), Galilema (GLM), and Melkasalsa (MS). The Merti tomato paste in cans was used as a control sample which is commercially available in the market. The raw tomato and pastes proximate contents were determined using standard methods of analysis. Moreover, fruit weight, firmness, viscosity, and pH analyzed by instruments whereas Vitamin C and titratable acidity were determined using titration method. The samples were analyzed in triplicate. The data were analyzed using SPSS statistical software to compare the mean values of tomato varieties at the probability level of P < 0.05. The results of raw tomato varieties proximate analysis showed in the range: moisture (94.1 - 96.3%), ash (0.58 - 0.63%), protein (4.94 – 5.25%), fat (0.01 - 0.49%) and fiber (1.7 - 1.78%) whereas pastes result shows moisture (73.4-83.9%), ash (2.9 - 3%), protein (11.46 – 15.14%), fat (0 - 0.5%), and fiber (2.36 - 4.09%). Raw tomato varieties physicochemical analysis results showed in the range: fruit weight (47.86 – 63g), firmness (4.09 – 4.13Kg), titrable acidity (0.541 – 0.462%), pH (4.32 – 4.51), viscosity (6.5 – 10.7mPa.s), natural total soluble solids (4.3 - 4.8°Brix), and vitamin C (16 – 17.6mg/100g) and color rating scale 6 whereas pastes natural total soluble solids (16 - 24°Brix), titrable acidity (0.73 – 1.0%), sugar-acid ratio (21.92 – 29.63), pH(4.3 – 4.5),viscosity (0.8 – 2.12Pa.s) and vitamin C (11 – 14.11mg/100g) and the color(13 – 17SRM). From all the above quality parameters, the most criteria for tomato paste varieties selection are total soluble solids, firmness, color, and moisture contents. Results showed that Galilea and Galilema have high total soluble solids (24°Brix) while Melkasalsa has low (16°Brix). Therefore, the study identified that local Galilema varieties are the best performance of paste at industry level. Key words: Tomato, Paste, Physicochemical Properties, Variety, Manufacturing, Proximate Analysis
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    Activated Carbon Preparation and Characterization from Flax Straw for Removal of Pb (II) Ions from Aqueous Solution and Industrial Wastewater
    (Addis Ababa University, 2021-09) Tayto, Mindahun; Shegaw, Ahmed (PhD)
    There are different modern technologies to remove heavy metals from industrial effluent. However, applying these modern technologies is impossible in all situations. Hence, investigating alternative technologies like adsorption by AC for such kinds of problem is very important. Considering this, the aim of this study was to prepare AC from flax straw and investigate its potential for the removal of Pb (II) ions from aqueous solution and paint industry wastewater. AC was prepared by chemical activation method using H3PO4 as activating agent. The effects of activation time, activation temperature and activating agent concentration on yield and iodine number were studied by using RSM. The effects of initial Pb (II) ion concentration, adsorbent dose, contact time and pH on removal efficiency were studied by using synthetic wastewater prepared from lead nitrate on a batch mode. The collected wastewater sample was characterized before and after treatment according to APHA methods. AC was characterized and results showed that the flax straw AC had 8.04% of moisture, 6.04% of ash, 18.615% of volatile matter, 79.421% of fixed carbon, 459.807 mg/g of iodine number and surface area of 489.455 m2/g. Physico-chemical characteristics revealed that raw wastewater had a concentration of 3.95 mg/L Pb (II), 158.52 mg/L BOD5, 2482 mg/L COD, and 652.667 mg/L TSS. The highest removal efficiencies of Pb (II) metal ion which was achieved from aqueous solution and paint wastewater were found to be 95.16% and 78.73%, respectively. The experimental data are fitted with pseudo-second order model and adsorption of Pb (II) on flax straw AC fits the model of Langmuir very well. The results suggested that flax straw AC can be used as adsorbent to remove Pb (II) ion from paint industry wastewater.
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    Activation of Peanut Shell Using Phosphoric Acid for The Bleaching Process of Niger Seed Oil
    (Addis Ababa University, 2019-06) Shikur, Wudu; Kumsa, D
    In this study, a two-stage process was conducted. The first stage was carrying out for the activation process of Peanut shell powder at different temperatures and concentrations to select the optimum parameters. The second stage was bleaching of Niger seed oil using the chosen activated peanut shell powder adsorbent. The peanut shell collected from Sululta, Ethiopia was activated by phosphoric acid, and further bleaching experiments were conducted to assess the activated powders effect on the bleaching capacity of Niger seed oil. The Two key parameters of the acid activation process were acid concentration and activation temperature. The highest bleaching capacity was obtained around 3M acid concentration and at 350 o C of activation temperature as optimal activation. The PSP and PAAPSP at optimal condition were characterized by XRD, FTIR and SEM with EDS. The results of the XRD showed that the PSP is composed of cellulose, hemicellulose and lignin polysaccharide. The XRD analysis of PAAPSP illustrated the presence of crystalline carbonaceous structure and different alumino silicate minerals. X-ray and FTIR data confirmed that acid activation degrades cellulose. The results of the analysis by Energy Dispersive Spectroscopy (EDS) showed that, presence of carbon, oxygen, silica, alumina and phosphorous. Full factorial Box Behnken design (BBD) experimental design was employed to correlate the bleaching parameters (temperature, time and dosage of PAAPSP) to the percentage color reduction for Niger seed. The result showed that the optimum condition for the bleaching process was a temperature of 110 o C, a period of 20 minutes and 3% PAAPSP dosage which resulted in 88.02% bleaching performance of the Niger seed oil. The experimental result was in agreement with the model prediction. Generally, the study has shown that the phosphoric acid activated peanut shell powder is a good adsorbent for the bleaching of the Niger seed oil. This research has further established that acid activated peanut shell powder has the capacity to remove not only pigments but also reduce the free fatty acid and peroxide value of unbleached oil.
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    Activation of Raw Bentonite (Afar Region) Using Sulfuric Acid for Rapeseed and Niger Seed Oil Bleaching
    (Addis Ababa University, 2017-06) Shemsu, Leena; Tekola, Beteley (PhD)
    In this study, a two-stage process was conducted. The first one was carrying out the activation process of raw bentonite at different conditions and the optimum parameter was chosen. The second process was bleaching of Niger seed oil and rapeseed oil using the chosen activated bentonite. The raw bentonite collected from Gewane in Afar region was activated by sulfuric acid and the design of various experiments in order to assess and simulate the effects of the acid activation of raw bentonite on the bleaching capacity of Niger seed oil is described. Two key parameters of the acidic activation, namely acid concentration and activation temperature, were considered. The highest bleaching capacity was obtained around 3M acid concentration and at 90oC of activation temperature as optimal activation. The raw and activated bentonite at optimal condition was characterized by XRD, FTIR and SEM with EDS. The results of the XRD showed that the raw bentonite is composed of montmorillonite, quartz, muscovite, hematite, feldspar and cristobalit. X-ray and FTIR data confirmed that acid activation affects both the octahedral and the tetrahedral sheets. The results of the analysis by Energy Dispersive Spectroscopy (EDS), showed that, presence of silica, alumina and iron as major constituents, along with traces of sodium, potassium, magnesium, calcium, and titanium in the form of impurities. These exchangeable cations were removed partially by acid attack. Full factorial experimental design was employed to correlate the bleaching parameters (temperature, time and dosage of clay) to the percentage color reduction for Niger seed and rapeseed oil bleached. The result showed that the optimum condition for the bleaching process was a temperature of 900C, a period of 30 minutes and 4 % clay dosage which resulted in 94.37% bleaching of the Niger seed oil. For rapeseed oil, the maximum bleaching efficiency, which is 96.01%, was obtained at 110 0C, a time period of 45 minutes and 1% clay dosage. The experimental result was in agreement with the model prediction. Generally, the study has shown that the clay is a good adsorbent for the bleaching of both oils. This research has further established that acid activated bentonite has the power to remove not only pigments but also reduce the free fatty acid of unbleached oils. Keywords: Bentonite, Acid activation, Characterization, Bleaching, Niger seed oil, Rapeseed oil
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    Adaptive Control Design for a MIMO Chemical Reactor
    (Addis Ababa University, 2004-07) Yimam, Abubeker; Venkatanarasaiah, D. (PhD)
    The major disadvantage of non-adaptive control systems is that these control systems cannot cope with fluctuation in the parameters of the process. One solution to this problem is to use high levels of feedback gain to decrease the sensitivity of the control system. However high gain controllers have two major problems: large signal magnitude and closed loop instability. The solution to this problem is to develop a control system that adapts to changes in the process. This paper presents the design of adaptive controller to a MIMO chemical reactor. The proposed adaptive controller is tested by using Math lab Simulink program and its performance is compared to a conventional controller for a different situation. The paper demonstrated that while the adaptive controller exhibits superior performance in the presence of noise the convergence time is typically large and there is a large overshoot. To resolve these problems of adaptive controller, the proposed controller is redesigned by modifying the adaptation law. And the results show a significant improvement in the performance of the adaptive controller without excessive increase in the adaptation rate. life of the low and middle income inner-city residents of Addis Ababa. Financial, institutional and legal problems are also seen as the major problems that hinder the implementation of LDPs in Addis Ababa
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    Adsorption of Heavy Metal from Constituent Waste Water by Tea Waste Adsorbent
    (Addis Ababa University, 2016-06) Oljira, Lalise; Kiros, Solomon (PhD)
    Most industries such as electroplating, textile, fertilizer, batteries, leather, and others in less developed countries discharge huge volumes of untreated wastewater into water bodies. The industrial wastewater may contain toxic chemicals in excess of the threshold level when released into the environment, particularly to the aqueous environment and soil; significantly degrade the quality of the water thereby affecting river health substantially and subsequently human health. There are several techniques for removing toxic chemicals such as ion exchange, membrane filtration, adsorption, irradiation and chemical and biological treatments. However, the adsorption method is believed to be the better option because it is cost-effective, efficient, simple and easy to operate, and environmentally friendly according to many studies. Accordingly, this method can be a preferable option for developing countries like Ethiopia, where advanced treatment technologies for high volumes of toxic industrial waste water are unaffordable. The aim of this work was to determine the potential of tea waste (TW) as a useful adsorbent for the removal of copper and zinc ions from aqueous systems. The study was conducted using batch experiments with constituted wastewater having copper and zinc ion concentration of 1000 mg·L-1. The effects of initial concentration, contact time and pH on adsorption efficiency were investigated. Adsorption isotherm was also studied. Generally, the result showed an increase in removal efficiency with increase in contact time, pH and decrease of initial concentration. The adsorption equilibrium data correlate well with Freundlich model and Langmuir model respectively for zinc removal and copper removal with regression coefficient (R2=0.9913, R2=0.981). The results showed that efficiencies of (TW) for the removal of copper and zinc ion were 95.98% and 99.80% respectively at optimum point of 5pH, 10ppm, and 120min. These results clearly indicate the efficiency of tea waste (TW) as a low-cost adsorbent for treatment of wastewater containing copper and zinc ions. Therefore, it is recommended that tea waste can be used, as a low cost and abundant source for the removal of heavy metals as an alternative to more costly materials. KEY WORDS: Copper, zinc, toxicology, adsorption, tea waste, batch study, atomic adsorption spectrometer.
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    Adsorption of Methylene Blue Dye from Synthetic Wastewater using Chitosan/graphite Composite Adsorbent; Statistical Optimization
    (Addis Ababa University, 2023-11) Soliyana Teshome; Shimelis Kebede (PhD)
    The study aimed to synthesize a chitosan/graphite composite (CGC) for methylene blue dye removal from synthetic wastewater using the impregnation method. Expanded graphite was prepared by reacting graphite with H2SO4 and H2O2 at room temperature, then washed, dried, and heated. The specific surface area of graphite increased from 1193.75m2/g to 1223.648m2/g. The composite adsorbent material was synthesized using the impregnation method, with chitosan to expanded graphite ratio of 75:25. The CGC was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller (BET) method, scanning electron microscope (SEM), and point of zero charge analysis. The optimized experimental design resulted in 98.61% removal efficiency at initial concentration of 5.24 mg/L, pH of 9.98 and contact time of 95.43. The adsorption of methylene blue dye onto CGC was best fitted with Langmuir isotherm, with an R2 value of 0.9974 and adsorption capacity of 98g/g. The kinetics of adsorption were best fitted to pseudo-second order with an R2=99.39.
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    Adsorption-Anaerobic Digestion coupling process for molasses vinasse Treating
    (Addis Ababa University, 2018-07) Mohammed, Seid; Shemelis, Kebede (PhD)
    The production of ethanol from biomass results in the co-current production of acidic material known as distillery spent wash or vinasse. It is generated at a rate of 10 to 15 times greater than the ethanol itself, and is characterized by a high dissolved organic matter content. Anaerobic digestion is the most effective methods for the treatment of such type of wastewater. In this work, a combined adsorption–anaerobic digestion treatment of distillery wastewater was studied in order to develop an effective procedure for increasing the anaerobic biodegradability of vinasse to reduce its environmental impact. The adsorption stage with banana peel as a pretreatment was evaluated for removal of phenolic compound. The removal of phenolic compound with this biosorbent was carried out using Box-Behnken experimental design taking 3 factors, adsorbent dose, contact time, and particle size. The maximum phenol removal recorded was 76.425% at the optimum condition (adsorbent dose of 20 g/L, contact time of 129.98 min, and particle size of 0.53 mm). Removals of 22% in chemical oxygen demand (COD) was obtained in this stage. Among the adsorption isotherm models analyzed, the Langmuir model fitted best to the experimental data with maximum adsorption capacity of 4.12 mg/g, and also the adsorption mechanism follows pseudo-second order model. The pretreated vinasse was undergone to an anaerobic digestion process in the second stage under mesophilic condition. After anaerobic digestion, a global removal of 84% in COD, and over 95% in phenols content were obtained. It was shown that, a combination of treatment method (i.e. banana peel biosorption and anaerobic digestion) is a promising option for simultaneous removal of phenol and COD from molasses vinasse under the stated conditions.
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    Aflatoxin Content of Peanut (Arachis hypogaea) in Relation to Shelling and Storage Practice of Ethiopian Farmers
    (Addis Ababa University, 2010-06) Legesse, Eshetu; Abate, Dawit (PhD)
    The threat of aflatoxin contamination in food commodities and its association with health risks in both animals and humans continues to raise increasing concern over years. In this research, A. flavus species found in association with peanuts in storage and their potential to produce aflatoxin in collected samples was determined. About 11 to 87% of collected peanut samples were infected with various moulds including Rhizopus sp., Fusarium sp., Aspergilus flavus, A. niger, other Aspergillus sp., Penicillium sp., and other undefined sp. Aspergillus flavus is known to be the most patent aflatoxigenic strains infects 80.69 % of the total samples analyzed. Eighty five percent of the tested isolates of A. flavus were capable for the production of aflatoxins. From the total of 52 peanut (Arachis hypogaea) samples analyzed, 38 (73.06 %) were positive for aflatoxin. The average levels of aflatoxins detected in the seed samples were between 0.57(from Babile new harvest sample) to 447.02 ppb (from Babile three month stored in pp bag). The higher level of toxicity is more than twenty times greater than the acceptable dosage (20 ppb: US Standards) in peanuts of three month stored after wet shelling. This research pointed out that the storage and shelling practice of farmers have effects in aflatoxin contamination in peanut despite enormous efforts to control this mycotoxin. Keywords: Peanuts (Arachis hypogaea), A. flavus, aflatoxins, shelling and storage practice
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    Ammonium Chloride Production and Optimization of Brine Ammoniation for Lime Removal in Leather Processing
    (Addis Ababa University, 2014-06) Moreda, Michael; Kaba, Tassisa (PhD)
    Leather industry occupies a place of prominence in Ethiopian economy in view of its massive potential for employment, growth and export. The need of import substituting leather processing chemicals from locally available feed stocks is an urgent matter both from economic and environmental point of view. One of the chemicals used in leather processing is ammonium chloride which is a deliming agent in Beam house operation. In this study, the production of ammonium chloride from proven available urea feed stocks ammonia, carbon dioxide and from the cheapest chlorine source sodium chloride which is readily available in Ethiopia, and its use and efficiency as a deliming chemical as compared to standard ammonium chloride is analyzed. A modified Solvay process approach was adopted in search of a route to the production of ammonium chloride locally. The method involves brine purification, ammoniated brine formation, carbonation of ammoniated brine, separation of sodium bicarbonate from ammonium chloride containing mother liquor, evaporation of ammonium chloride filtrate, cooling of the evaporated ammonium chloride filtrate to crystallize, centrifugation and drying of ammonium chloride which is collected as a white solid crystal of 98.5 - 99.5 wt.% NH4Cl. This preparation met the established specification for ammonium chloride of Indian Society for Testing and Materials (ISTM). The maximum yield of ammonium chloride (92.5%) was produced when the brine ammoniation reaction was carried out at a temperature of 100C, ammonium solution to saturated brine molar ratio of 2 and reaction time of 1 hour. Therefore, these values can be considered as optimal for ammonium chloride production using ammonium solution, dry ice and saturated brine in batch reactor. The reaction temperature was varied in the range of 100C - 200C, ammonium solution to saturated brine molar ratio was varied in the range of 1 – 3; and reaction time was varied in the range of 0.5 - 1.5 hours. Testing of the optimal product on leather met the IULTCS standards.
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    Anaerobic Co-Digestion of Slaughterhouse Wastewater with Water Hyacinth (Ecchornia Crassipes) For Biogas Production Using Rumen Fluid as Inoculum: Characterization and Parametric Optimization
    (Addis Ababa University, 2021-10) Rakeb, Kifle; Zebene, Kiflie (PhD)
    The purpose of the present study was to characterize and optimize the co-digestion of Slaughterhouse wastewater with Water Hyacinth (WH) for biogas production using rumen fluid as inoculum. The slaughterhouse wastewater and water hyacinth were first characterized to determine their potential for biogas production. Water Hyacinth reducing sugar content was determined (11.94 g/L) using dinitrosalicylic acid (DNSA). Co-digestions were carried out in batch reactors. The effects of substrate composition (ratio of WH to SWW), hydraulic retention time and pH on methane production and COD removal efficiency were investigated and optimized using RSM-Optimal (custom) design. Accordingly, the optimum methane production and COD removal efficiency were found to be 76.2% and 59.1%, respectively at HRT of 40 days, a substrate composition of 50%SWW: 50%WH and a pH of 7. Furthermore, the bio-digestate was investigated for fertilizer potential. Results show its nutrient values were below the FAO suggested values. FAO suggests a minimum of 5% sum (N+P+S) for an organic fertilizer. Results show that co-digestion of SWW with WH is promising way for producing biogas and simultaneously to control the spread of WH. In addition, it is suggested to blend the bio-digestate with organic manure for enhancement of fertilizer potential.
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    Analysis and Optimization of Para-Xylene Production Process From Sugarcane Bagasse
    (AAU, 2018-06) Brhanu, Gebreslassie; Hundessa, Dessalegn (PhD)
    Lignocellulosic biomass has a great potential for biofuel and fine chemical productions. This study focused on the effective conversion of the lignocellulosic biomasses, particularly sugarcane bagasse to the most valuable aromatic hydrocarbon called Para-xylene via two-step acid-catalyzed hydrolysis, dehydration, hydrogenation, and Diels-Alder cycloaddition reaction steps. Para-xylene is one of the most important aromatic hydrocarbons, which is used for the production of purified polyethylene terephthalate (PET), in which it is used for the production of world plastics. So, the production of fine chemicals from biomass helps to reduce the dependence of the imported oils as well as used to improve the overall economic and sustainability of the world. In this study, the effect of operating variables on the Diels-Alder cycloaddition reaction between the biomass-derived furan and the suitable dienophile, which is called Maleic anhydride, was investigated and optimized using the most reactive and selective Lewis acid catalyst (AlCl 3 ). In the Diels Alder cycloaddition reaction, the effects of reactant molar ratio, catalyst loading and reaction time on the conversion of DMF and the yield of dimethyl benzoic acid was investigated and optimized using Design expert®7 software. As the result, 41.4% conversion of DMF and 64.6% yield of dimethyl benzoic acid were obtained at the optimum values of the operating variables such as molar ratio of the reactant, catalyst loading and reaction time. And also, the effects of acid concentration and reaction time on the dehydration of dimethyl benzoic acid to Para-xylene were investigated, and 70.36% conversion of dimethyl benzoic acid and 49.66% yield of Para-xylene were obtained. In addition to this, the final product (Para-xylene) was analyzed using FTIR and GC-MS. As the result, the FTIR result is the same with the standard functional group of 1,4-dimethyl benzene, and 30.88% composition of Para-xylene were obtained using GC-MS.
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    Analysis of Fillers for Production of Alternative Building Materials Using Magnesia Cement
    (Addis Ababa University, 2008-01) Tadele, Tamrat; Assefa, Berhanu (PhD)
    Fillers, which are available in the country, are essential for the production of magnesia cement boards. These include pumice and lignocellulostic fillers such as bagasse, sawdust and coffee husk. While applying these fillers to produce the boards, their nature and performance should be studied. Magnesia cement was used as binding materials; varying boards were produced for different proportion fillers with fixed ratio of magnesium oxide and magnesium chloride. For the board produced, density, water absorption, and setting time as well as mechanical properties such as the compressive strength and the bending strength determined. In addition, the effects of different fillers on the properties of the board and production cost were examined. When the saw dust and coffee husk filler substituted the current used bagasse filler, the water absorption and setting time of the boards reduced. While the density, bending strength and compressive strength of the board increased. The mix ratio of fillers and pumice powder had also influence on the physical and mechanical property of the boards. The test results showed as the proportion of the pumice increased, the mechanical strength of the boards increased and the setting time of the cement paste reduced. The cost analysis showed that the saw dust board production cost was lower than coffee husk and bagasse board cost. While the production cost of the coffee husk board was slightly higher than others. viii In aim of production of filler boards as alternative building materials are, the cost comparison showed in the possibility of producing relatively low price than the hollow concrete blocks included finishing work cost.
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    Anchote (Coccinia abyssinica (Lam.) Cogn) Starch and Flour Modification Using Hydrothermal Treatments and Valorization as Functional Ingredients in the Development of Food Products
    (Addis Ababa University, 2024-06) Yohannes Toles; Shimelis Admassu (Prof.)
    Anchote (Coccinia abyssinica (Lam.) Cogn) is an underutilized root and tuber crop indigenous to Ethiopia and potentially an important source of starch. The native users cultivate anchote for its medicinal, economic, nutritional, and socio-cultural benefits. The anchote tuber has a significant number of beneficial nutrients, such as carbohydrates, protein, fat, fiber, and different minerals. Compared to other root and tuber crops, this crop is renowned for its vital protein and calcium content. Anchote tubers have a high starch content (75–79%), making them a suitable alternative source of starch for use in several industrial applications. However, understanding the physicochemical properties of starch generated from such underutilized roots and tubers is critical in order to develop unique value-added products. The quality of starch is determined by its physicochemical properties, which include its morphology, particle size, amylose content, crystallinity, thermal properties, and swelling powers. However, there is still a dearth of studies on important anchote starch properties from different genotypes: the rheological properties of anchote starch gels, intrinsic characteristics like storage texture kinetics, and the effect of starch concentration on the gel rheological properties of anchote starch gels, which are so important for their food applications. Thus, this study examines the properties of native and hydrothermally modified starches from four anchote tuber cultivars and compares them to potato and cassava starches. It also investigates the effects of hydrothermal modifications on the pasting, morphological, and thermal properties of anchote flour-starch mix. The study also examines the impact of partial replacement of gluten-free teff flour with modified anchote flour-starch mixes on gluten-free biscuits. The granule sizes of the anchote cultivars varied, but they all exhibited a B-type crystalline structure similar to that of potato starch. The amylose content of anchote starches ranged from 15.8–22.3%. The phosphorus in anchote starches ranged from 82 to 93 mg/100 g, which is much higher than that of potatoes and cassava (60.3 and 5.8 mg/100 g, respectively). This high phosphorus content influences the functional properties of anchote starches, making them well-suited for use in various types of noodles, glucose syrups, and viscous products. Anchote starches had a significantly different gelatinization temperature and enthalpy than potato and cassava starches, ranging from 60.97 to 69.33 °C and 16.87 to 18.38 J/g. Significant differences were also noticed in the pasting properties of anchote cultivar starches. In comparison to potato and cassava, they demonstrated greater stability to heating and shearing, with higher trough viscosity (TV) (2046 to 2280 mPa·s), lower breakdown viscosity (BV) (248 to 487 mPa·s), and a higher final viscosity (FV) (3409 to 3686 mPa·s). These properties are significant in the food processing industry and when high gel viscosity is needed after cooling. In comparison to cassava and potato gels, anchote starch gels displayed considerably greater viscoelastic moduli and much lower (tan δ)1 values. These rheological features are typical of true gels. According to the present findings, anchote starch had acceptable color characteristics that were similar to those of potato and cassava starches. The anchote starch exhibited lightness (L*) and whiteness values above 95 across different cultivars. As the cooking temperature increased from 40 - 90 °C, the swelling power (SP) and water solubility index (WSI) of anchote starches demonstrated a clear rise. It's important to note that the rate of increase differed significantly from that of the control starches, with anchote starches showing a lower increase compared to potato starches and cassava starch in the following order: anchote starches < potato starches < cassava starch. Compared to potato (PS) and cassava (CS) starch gels, anchote starch gels had lower (tan δ)1 values and demonstrated better elasticity, withstanding higher stresses before breaking their structure. In addition, they were more stable at higher concentrations and exhibited higher viscoelastic moduli even at lower concentrations than the PS and CS gels. The study of the textural evolution of the gels over storage revealed that anchote starch gels were less adhesive than PS gel and had initial and final hardness that was significantly higher (≥40%) after 192 hours. The hydrothermal treatments (ANN and HMT) significantly altered the pasting characteristics of anchote starches. The pasting properties (PV, TV, and BV) were decreased significantly after HMT and ANN treatment. HMT significantly reduced the PV of anchote starches compared to ANN treatment. The lower BV values obtained in all studied cultivars show the higher stability of modified anchote starches to thermal treatment and mechanical shearing. The ANN treatment significantly (p < 0.05) increased the final viscosity (FV) compared to HMT and native anchote starches. The rheological property shows the dominance of the elastic over the viscous behavior, having higher G′ values than G″ in the entire frequency range for all studied starch gels. The G′, G′′, and (tan δ)1 values were significantly decreased upon HMT treatment, while ANN treatment significantly increased the G′ and G′′ of anchote starches related to the native starches. Both HMT and ANN increased gelatinization temperatures and decreased enthalpy in all cultivars studied. The study found that the B-type structure of anchote starches remained unchanged after hydrothermal treatments. However, ANN and HMT treated anchote starches had higher relative crystallinity compared to native starches. These results showed that ANN and HMT treatments efficiently modified the rheological, pasting, and thermal properties of anchote starches isolated from four cultivars. The hydrothermal treatments significantly (p < 0.05) affected the pasting properties of anchote flour (DF) and anchote flour-starch mix (DFS). The PV and BV of DF and DFS anchote samples were decreased upon ANN and HMT treatment. The addition of anchote starch to anchote flour significantly improved color characteristics, and carbohydrate contents in both native and hydrothermally modified samples. The study showed that HMT and ANN treatment significantly (p < 0.05) reduced the phytate, tannin, and total phenol contents in both DF and DFS, while the HMT treated samples had the lowest phytate contents compared to ANN and native samples. Likewise, the study showed that the hydrothermal treatments significantly affected the hydration properties (WAC, OAC, SP, and WSI) of studied DF and DFS. The HMT and ANN treatments did not affect the FTIR spectra of studied anchote samples. However, hydrothermal treatments raised the gelatinization temperatures (TO, TP, and TC) of DF and DFS. The results revealed that hydrothermal treatments enhanced the thermal stability of DF and DFS samples. As a result, it appears that the HMT and ANN anchote flours would be appropriate for applications requiring heat stability. The growing consumer demand for gluten-free food products has led to an increased need for innovative gluten-free ingredients that offer improved nutritional benefits. Thus, this study examines the impact of the partial replacement of gluten-free teff flour (TF) by modified anchote flour-starch mixes (HMT-DFS and ANN-DFS) on the physical, nutritional and sensory characteristics of gluten-free biscuits. The result showed that the color, proximate compositions, pasting, and functional characteristics of the gluten-free flours used in this study varied significantly (p < 0.05). HMT-DFS and ANN-DFS flours had higher L*, a*, b*, and whiteness values compared to TF flour. The protein contents of gluten-free HMT-DFS and ANN-DFS flours were almost similar, while those of TF flour had a slightly higher protein content. But HMT-DFS and ANN-DFS had significantly higher ash contents and lower fat and fiber contents compared to TF. The pasting properties of the studied flour samples varied significantly (p < 0.05). The lowest BV value of the ANN-DFS and HMT-DFS samples shows that they have the highest stability to thermal treatment and mechanical shearing; thus, these samples are ideal functional ingredients in formulations of food products that require higher thermal treatments. The study showed that substituting gluten-free HMT-DFS and ANN-DFS flours for teff flour did not affect biscuit thickness, but slightly increased spread ratio. However, the inclusion of HMT-DFS and ANN-DFS significantly influenced color features. The study also found that incorporating anchote flour-starch mix into teff flour significantly affected color characteristics at higher substitution levels. The study found that gluten-free biscuits AB10, AB20, HB10, and HB20 had superior physical and sensory properties compared to control biscuits. These biscuits had higher ash, fat, and fiber contents than the control WB biscuits and comparable values with the control TB biscuits. The study also found that incorporating a modified anchote flour-starch mix in gluten-free teff flour biscuits enhanced proteins, carbohydrates, energy values, and mineral contents, making it a useful functional ingredient for gluten-free formulations. Therefore, the present findings showed that the hopeful potential utilizations of modified anchote flour and starches as functional ingredients in food processing, product development, novel food product formulations, and additional industrial applications.
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    Application of Hydro-Metallurgy (Wet Etching) To Recovery A Precise Metal (Gold) From A Wasted Printed Circuit Broad (WPCB): Case Study of Ministry of Information Communication and Technology (MICT)
    (Addis Ababa University, 2017-11) Kidist, Wendium; Berhanu, Assefa (PhD)
    This thesis research is undertaken with the main objective of assessing the existing e-waste management in Ethiopia by taking ministry of information and communication technology as a case study and to propose e-waste recycling approach (hydrometallurgy) to recover gold. To meet the research objectives a blend of qualitative and quantitative methods were used where unstructured key informant interviews, Observation of the e-waste disposal site from the selected govermental organization and computer recycling and refurbishment center (CRTC) at Kality were combined with Case study at laboratory scale hydro-metallurgy to recover gold from waste printed circuit boards (PCB).It is found that E-waste is expected to be a huge problem in the future, given the rise in consumption trend of the target institutions and the general importation trend of the country. There is high accumulation of old ICT equipment in the target institutions of the study. Parallel to that, The current trend of lifecycle management of this electronic waste at CRTC and at Addis Ababa University is out date and the precious metals like that of gold are not properly recycled.in addition by applying hydrometallurgical approach (wet etching), from a sample of 500 gm printed circuit board 1.66 gm of gold was recovered with mineral composition of 99.71% Au, 0.12% Ni,0.16% Cu. this research under takes an experimental procedure where, At the start of the experiment 20 gram of fingers was used for on batch. And added to on an empty beaker. The next step will be dilution of the hydrochloric acid, hydrochloric acid with the concentration of 35% will be diluted by adding 57 ml of water on the biker. Finally we can get hydrochloric acid with the concentration of 15% with a volume of 43 ml. next the addition of hydrogen per oxide which has a concentration of 15% with a volume of 50 ml and the reaction proceeds for 6hr after that The combination of hydrochloric acid and hydrogen per oxide will detached the gold fingers from the silicon chips and a film of gold fingers will float, finally Using kitchen strainer and a large coffee filter the gold foils will be filtered out of the acid peroxide solution. The results were obtained by taking Hydrochloric acid to hydrogen per oxide proportion(1:0.5,1:0.4,1:0.9),retention time( 6hr,12hr,21hr) and hydrochloric acid concentration of ( 5%,10%,15%) as factors and on the basses of the study the optimum conditions to get a maximum amount of gold (0.2455 gm) was HCl: H 2 O 2 proportion of (1:0.5), HCl concentration (10%) and retention tine (12hr) .In conclusion, to draft a solution and act accordingly, the government through its instruments should put a system in place.
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    Approach Towards High Performance Water Vapour Permeability Upper Leather from Goat Skin
    (Addis Ababa University, 2014-09) Mekonnen, Bekele; Muralidharan, B (PhD); Das, B.N. (PhD); John, Sundar (Mr.)
    The mechanism of increasing WVP Goat upper leather, the processes have been developed. These process developed during the project were, increased percentage of bating enzyme during bating process, increased the duration time of liming process, avoided the qubracho powder and acrylic syntan during retanning process, decreasing of synthetic fat liquor and instead used semi synthetic fat liquor, increased the percentage of degreaser during degreasing process, after wet blue for 2hrs treated the leather with 1% of urea and acetic acid. For each process, the physical properties such as WVP, tensile strength, percentage elongation at break, tear strength and grain crack were carried out. The result obtained from each process at crust and finished listed in chapter 4 in table form. The experiments carried out for both control and experiments for all experiments.
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    Approaches to Near Zero Utilization of Water in the Post tanning Operations of Leather Processing
    (AAU, 2014-09) Solomon, Fessehaye; K J., Sreeram (PhD)
    Any industrial activity would generate waste, whose form would be as solid, liquid and/or gas. While industrialization is important to a nation’s economy, the wellbeing of human kind is even more important. The conflict for water between mankind consumption and industrial activity is increasing day by day as the population is increasing. An industrial activity like leather processing is a water intensive process, with most of the industries consuming 35 L of water to process every kilogram of hide/skin. While it is easy to wish away an activity like leather processing, an analysis of the relevance of this industry to Nation building would reveal that this is the only industry that uses a byproduct of meat industry, viz., skin and converts it into a fashion commodity. In the transformation, a host of rural men and women are involved directly or indirectly. For the nation, it is a good source of export income. This research work is one of an out-of-the-box thinking of systematic reduction and utilize known concepts of recycle, reduce or recovery of used water from processing. For this, the methodology has relied upon the replacement of water with environmentally benign and clean/green solvent for transporting chemicals into the skin matrix instead. The work consists of identifying the appropriate solvent or solvent mixture that a) did not have any adverse effect on the fibre structure, b) where a significant number of leather auxiliaries could be dissolved or dispersed and c) could be easily recovered and reused. The combination of solvents was selected from amongst reported clean/green solvents and the solubility / stability of the auxiliary dispersions determined by the measurement of the zeta potential of the system. The initial interaction of the dispersed auxiliaries with skin matrix being one of adsorption, various models of adsorption can be fitted to understand the nature of binding. The physical and visual properties of developed leathers have also been compared.
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    Assesment of Maerua Subcordata Root As Biosorbent for The Removal of Cr (Vi) Ions From Tannery Waste Water
    (Addis Ababa University, 2015-05) Berecha, Mesfin; Negusie, Agizew (PhD)
    Chromium containing wastes are generated by industries such as leather tannery, electroplating, paint and pigment manufacturing. The form of Cr (VI) is responsible for human carcinogen as well as water and soil pollution. The main objective of the present study was to evaluate the possibility of using Maerua Subcordata as a Biosorbent for the removal of Cr (VI) from tannery waste water and aqueous solution. The study was conducted in Addis Ababa university Environmental science laboratory center and Ethiopian leather industry development institute laboratory center, from January to May, 2015. Maerua Subcordata was collected from South Omo Zone DasenechWoreda and cut in to small pieces, dried in the sunlight and grind to produce the powder, treated with H3PO4 (45%w/w). Physical characterization such as moisture content and bulk density of activated Maerua Subcordata was done and it was found low moisture content which indicates high quality of the biosorbent.The Biosorption of Cr (VI) from aqueous solution and real tannery waste water by activated Maerua Subcordata was studied. The biosorbent was characterized by FTIR spectroscopy and characterization of the Maerua Subcordata suggested the possible contribution of carboxyl and hydroxyl groups in Cr (VI) Biosorption. The Biosorption efficiency of the Maerua Subcordata was dependent on the pH of the Cr (VI) solution, with pH 3 being optimal. The removal rate of Cr (VI) ions increased with increase in contact time and remained constant after an equilibrium time of 60 min. The removal of Cr (VI) ions increased with increase in biosorbent concentration with the optimal biosorbent dosage at 125 mg/L. Both Langmuir and Freundlich model were followed by adsorption of Cr(VI) on activated MaeruaSubcordata. But Langmuir model best describes the adsorption data with coefficient of determination (r2) value 0.993.The maximum adsorption capacity obtained from Langmuir model is 4.54mg/g.The RL value obtained from Langmuir model shows the adsorption is favorable. When applying the biosorbent to real waste water 86.5% removal efficiency was obtained. The reduction in efficiency might be due to the presence of interfering ions which compete with Cr (VI) ion for Biosorption. Therefore, the study revealed that the activated Maerua Subcordata could be used as an excellent biosorbent for the removal of Cr (VI) chromium from Tannery wastewater and aqueous solution. Key words: Hexavalent chromium, Activated Maerua Subcordata, Biosorption