Process Engineering

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    Production of Lactic Acid from Taro Waste Starch:Comparative Analysis of Different Lactic Acid Bacteria Strains and Exploring their Potential as Bio preservative
    (Addis Ababa University, 2024-02) Tensae Abera; Andualem Bahiru
    This study aimed to optimize fermentation parameters for maximizing lactic acid production from taro waste starch. Three bacterial strains, namely Lactococcus lactis, Enterococcus faecalis, and Lactobacillus paracasei, were selected for evaluation. The growth performance of these strains was assessed using an initial one variable at a time experimental design (OVAT). Each.variable, including temperature, incubation time, and pH, was varied individually while keeping the others constant to evaluate their effects on lactic acid yield. After the initial assessment, the fermentation parameters were optimized using response surface methodology with a central composite design. The optimized conditions were determined based on two replication experiments and the results from the analysis. The aim was to achieve maximum lactic acid yield from taro waste. Among the three bacterial strains evaluated, Lactococcus lactis demonstrated the highest potential for lactic acid production. Comparative analysis revealed that Lactococcus lactis outperformed Enterococcus faecalis and Lactobacillus paracasei in terms of lactic acid production. The optimization process confirmed the suitability of Lactococcus lactis for achieving higher yields of lactic acid from taro waste. Under the optimized conditions of a fermentation temperature of 35 °C, a fermentation time of 48 hours, and a pH of 6.5, Lactococcus lactis achieved the highest lactic acid yield of 33.74 g/L. The study suggests exploring alternative bacterial strains and considering factors beyond growth potential when evaluating strains for lactic acid production. Additionally, the potential use of lactic acid as a preservative for fruits and other food items can be further explored based on the study's findings.
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    Synthesis and Characterization of Frankincense Scented Castor Oil Body Soap
    (Addis Ababa University, 2023-09) Eleni Tesfaye; Anuradha Jabasingh (PhD)
    Scented body soap is a type of soap that has been infused with fragrance or essential oils. This gives the soap a pleasant smell that can last for hours after bathing. Scented body soap is available in a wide variety of scents, so there is something to suit everyone's taste. In this thesis work the extraction of oil from castor seeds and infusion of frankincense and their utilization to produce soap has been conducted. The soap has been produced from castor seeds by using pre-treatment of castor seed, extraction of castor oil, neutralization and saponification methods. The extraction and refining of castor oil using stage wise equipment is carry out. In this project, the castor seed oil was extracted at a temperature of 80 and a time of 5 hr. by screw press. And the oil yield of 35% was obtained. Frankincense scented castor oil body soap was synthesized using the cold process method. The soap was characterized using Fourier transform infrared (FTIR) spectroscopy, which revealed the presence of functional groups indicative of fatty acids, esters, alcohols, methyl groups, and aromatic compounds. The soap was also evaluated for its lathering ability and moisturizing properties. The soap was found to be soft, have a good lathering ability, and be moisturizing. The saponification parameters used were temperature in the range of 85 to 90 oC, water to lye ratio in the range of 1.5 to 2 hr. and castor oil volume in the range of 5 to 10ml. The optimized conditions were at a temperature of 85 oC, water to lye ratio of 1.75 and a volume of castor 10ml.stable lather, fluffy lather, and moisturizing optimized. The FTIR spectrum of the soap showed peaks at 1745.6 cm−1, 2852.6 cm−1, and 2921.8 cm−1, 719.8 cm−1 which are indicative of the presence of carbonyl (C=O) groups, methyl (CH3) groups, and aromatic (C=C) groups, respectively. The presence of these functional groups is consistent with the expected composition of the soap, which is made with castor oil, frankincense essential oil, and sodium hydroxide. The optimized stable lather, fluffy lather and moisturizing, value found in the entire batch studied were 3.2, 9.7, 6.9, 9.99 respectively. The moisturizing properties of the soap were evaluated by measuring the skin moisture content of participants before and after using the soap. The results showed that the soap significantly increased the skin moisture content of the participants. Overall, the frankincense scented castor oil body soap was found to have good physical and chemical properties. It is a soft, lathering, and moisturizing soap. The soap is also made with natural ingredients, including frankincense essential oil, which is known for its many therapeutic benefits.
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    Extraction, characterization and optimization of Botanical Gin flavor from Juniper berries, Cassia bark and Ginger
    (Addis Ababa University, 2023-10) Melkamu Getaneh; Shegaw Ahmed (PhD)
    The botanical gin flavor was extracted from juniper berry as the main ingredient in a variety of ways. Quality was never stays the same and the yield of flavor and quality was influenced by different factors. The cheapest approach for flavor extraction in this instance was the water distillation using ethanol as a solvent method. The factor variable which affect the extraction process was botanical weight and alcohol concentration and the response was yield and sensory evaluation analysis. At 0.5 kg of botanical weight and 35% alcohol concentration in the extraction experiment, the minimal oil yield of 0.78% was obtained. A 1.5 kg botanical weight and a 50% alcohol concentration produced the highest oil yield of 2.76%. The physico chemical properties of the flavor studied for the optimum yield showed that the flavor was odorous and colorless, having 1.36619 refractive index value at 25oc, 1.108cp dynamic viscosity, 75oc boiling point, 0.8569 specific gravity, 4.84 pH, 0.307 degree optical rotation, 0.16 ml/g acid value, 2.44ml/g iodine value, 0.08% free fatty acid and 21.4 oBrix. The chemical composition of the flavor identified by GC-MS had β-pinene (4.89%), Terpinolene (8.57%), Cyclopropane, trimethyl (2-methyl-1-propnylidene) (8.35%), citronellol (6.34 %), γ-terpinene (1.60%), β- humulene (4.35%), globulol (4.23 %) and citral (2.90%). Gin liquor's sensory qualities was also assessed and obtained a good taste at 1.5kg botanical weight and 50% alcohol concentration at which both response were having 95.5% desirability. The findings of this investigation showed that the gin flavor extracted from procera juniper berry, cassia bark and ginger satisfy the requirement.
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    Synthesis of Ethyl Ester Sulfonate Surfactant (EESS) from Castor Oil via Transesterification and Sulfonation for Detergent Application
    (Addis Ababa University, 2023-11) Dibora Marie; Nurelegne Tefera (PhD)
    Due to the need to preserve natural resources, there is a growing need for renewable and biodegradable raw materials for industrial production. According to oleochemistry research, renewable resources have advantages over petrochemicals that make them ideal for making ecologically and consumer-friendly goods. In this investigation, unusual and environmentally friendly methods were used. Transesterification of castor oil was followed by sulfonation with sulfuric acid to produce anionic ethyl ester sulfonate (EES) surfactant. The synthesis of fatty acid esters from castor oil utilizing ethanol as a transesterifying agent and an alkaline catalyst was improved using a box behnken experimental design that took into account variables (reaction duration, catalyst quantity, and oil:ethanol molar ratio). Using a response surface curve and analysis of variance, the impacts and significance of the models on the response variable and ethyl ester yield produced from castor oil were investigated. The best yield was obtained using an oil:ethanol molar ratio of 1:16, a catalyst concentration of 1.00 wt.%, and an 80-minute reaction period. The effects of the EESS sulfonation reaction variables (sulfonation temperature, sulfonation duration, and sulfonating agent/ethyl ester (EE) molar ratio) on yield were studied using a one variable at a time experimental design (OVAT). According to the OVAT study, the best sulfonation settings for synthesizing EESS from castor oil were 80°C sulfonation temperature, 3.00 hours sulfonation duration, and a molar ratio of 1:1 H2SO4/EE, resulting in an EESS yield of 78.4%. The FTIR and NMR (-CH) groups, as shown by the FTIR and NMR (-CH) groups, were verified in the synthesized product, indicating the intended EESS product. EESS had a critical micelle concentration of 1.57 mol/L and an active matter concentration of 64.35%.
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    Production, Characterization and optimization of Food-grade Lubricant from the Rapeseed
    (Addis Ababa University, 2023-10) Yemariamnesh Mamuye; Solomon Kiros (PhD)
    In food processing manufacturing line, Cross-contamination is a major concern for any equipment used in the handling, packaging or processing of ingredients used in the food or beverage industry. In this research work, the production, purification and characterization of food grade lubricants from rapeseed are performed by double transesterification conversion methods. Experiments on the production and purification of food grade lubricants were performed according to standard scientific procedures. The rapeseed oil was extracted in the Soxhlet apparatus using normal hexane, and the relevant physicochemical properties (viscosity, density,acid value, free fatty acid value, PH and saponification number )were measured and analyzed in accordance with the ASTM and EN standard of oil quality. In addition, Rapeseed biodiesel was produced in the first transesterification conversion process using the solvent ethanol and NaOH used as catalyst and the same quality parameters as oil was done rapeseed biodiesel. Finally, food grade lubricants were produced from rapeseed biodiesel, ethylene glycol solvent and KOH were used as catalyst. Molar ratio, temperature and catalyst concentration were among the main variables of the experimental process studied. The box-Behnken design was applied in the manufacturing process in the design software to achieve the lubricating product interaction and individuality. The maximum product 94% was obtained at a temperature of 165ºC, the molar ratio was 3:1 and a 1% catalyst concentration by weight was consumed. The properties(density,viscosity,acid value, pour point, cloud point and flash point) of the manufactured food grade lubricants have been tested and conformed to ASTM quality specifications of food grade lubricant.
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    Optimization and Characterization of Briquettes Developed from Wheat Straw and Coffee Husk as an Alternative Energy Source In Cement Industry
    (Addis Ababa University, 2023-10) Misganaw Workneh; Shegaw Ahmed
    The process of making cement uses a lot of energy and produces emissions. Both the overall environmental impact of the cement industry and energy security are enhanced by the substitution of alternative fuels for coal. Because they are widely used in the making of cement, fossil fuels like coal, coke, and heavy fuel oil are not renewable and are predicted to release massive volumes of greenhouse gases (GHG) into the atmosphere during their life cycle, which includes mining, processing, transportation, and burning. This study looked at whether briquetting wheat straw and coffee husks would be a suitable alternative energy mix for cement pyro processing. Understanding the physiochemical and thermal properties of raw coffee husk, wheat straw, and mixed briquetted pellet required characterization for proximate analysis, final analysis, calorific value, bulk density, and ash composition of the fuel. Box Behnken design (BBD) was used to optimize process factors that impact the calorific value, such as particle size (<100μm, 100 ~ 175μm, and 175 ~ 250μm), mixing ratio (30%, 50%, and 70%), and carbonization temperature (300°C, 350°C, and 400°C). The findings indicated that the optimized parameters were as follows: a maximum calorific value of 5616.52 Kcal/kg, a mixing ratio of 70% coffee husk to 30% wheat straw, and a particle size of around 100μm. Lastly, the calorific value, volatile matter, moisture content, ash content, and fixed carbon content of the briquette have all been measured and found to be 5676.24 Kcal/Kg, 52.5%, 3.5%, 7.6%, and 39.84%, respectively
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    Statical Process Optimization on Adsorption of Phenol from Water Using Activated Carbon Prepared from False Banana (Enseteventricosum) Leaf
    (Addis Ababa University, 2023-10) Mohammed Keder; Anteneh Wodaje (PhD)
    The reason for this current study was to examine the potential of an adsorbent produced from EL to recover phenol from wastewater. Using agricultural wastes as valuable resources to create ACs from biomass wastes is one of the greenest resolutions. The main objective of this study was to use a chemical activation technique to produce ACs from readily available waste EL. An essential property for the synthesis of AC is the EL's cellulose concentration (18.4%), lignin level (10.3%), MC of 8.35%, VM of 71.09%, AC of 3.28%, FCC of 17.28%, and yield of 49.30% at 400°C. With a nitrogen flow rate of 150ml/min, the process of carbonization was conducted for 30, 60, and 90minutes at 400, 500, and 600°C. The char product was treated with 37% phosphoric acid (H3PO4) at diverse impregnation ratios (0.5, 1 and 1.5). It was found that 500°C, a 60-minute contact period, and an impregnation ratio of 1 in AC5 were ideal for the production of AC. With respect to surface area (1023m2/g), iodine number (984mg/g), and total pore volume (0.45cm3/g), AC5 was the largest. Scanning electron microscopy (SEM) analysis showed that the samples' uneven surface structure. Several functional groups that aid in adsorption was found when Fourier Transform Infrared Spectroscopy (FTIR) was examined. Using phenol as a separate adsorbate and the ideal conditions (PH=6, adsorbent dosage=0.4g, initial concentration=10mg/l, and contact time=120min) at room temperature, the adsorption capacity of generated activated carbon (AC5) was investigated. It was demonstrated that as initial concentration increased, the capacity of adsorption increased. The maximal phenol elimination capability of the AC5 adsorbent is 95%. With the aid of the model, a relationship between the three experimental variables and the percentage of elimination was constructed. It looked into the phenol adsorption equilibrium isotherms utilizing the Freundlich, Temkin, and Langmuir isotherm models. For the concentration range of 10-150 mg/L, the monolayer adsorption capacity was 5.80mg/g, according to equilibrium data that followed the Langmuir model. There were kinetic analyses done. It was discovered that the data fit a pseudo-second order model. The best phenol elimination was obtained with an initial phenol PH of 6 and contact duration of 80 minutes. The study concluded that phenol could be effectively removed from aqueous solutions using activated carbon obtained from discarded Enset leaves.
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    Characterization-and Energy Enhancement of Dawuro Coal Using Froth Flotation and Alkali/Acid Leaching
    (Addis Ababa University, 2023-10) Leager Minwuyelet; Abubeker Yimam (PhD)
    Ethiopia has huge deposits of low-rank coal, which is characterized by calorific-value (an_ average_4,500_kcal/kg), high_ash_content (up to 50%), high moisture content (up to 35%) and high volatile matter. Thus, the country_is_still dependent-on partial import of better quality-coal,_and so, significant amount of money in foreign-exchange is spent to meet the demand. Therefore, this study was carried out on domestic coal beneficiation by applying the froth-flotation and alkali-acid leaching, sequentially, for_enhancing_the_quality_of Dawuro Coal, in Southwestern-Region_of_Ethiopia. The Design-Expert-(version-13) software was_used for the experimental_design_and the RSM_with_BBD were applied for modeling_the_influence of some factors on the_performance_of flotation and_alkali-acid leaching experiments. Flotation experiments were conducted by considering particle_size, collector-and_frother-dosages as independent variables, and_then, alkali- and acid-leaching experiments were carried out, sequentially, both by using leaching concentration, temperature and time as independent variables. For each, ash-reduction was defined as process-response (dependent variable). The test_results revealed that the resulted ash-reduction models were found to_be statistically_significant and also the_predicted_values were in_good_agreement with_the_experimental results – with R2 value of 0.9801, 0.9858, and 0.9711 for ash-reduction in flotation, alkali and acid-leaching, respectively. Results revealed that particle-size for flotation and leaching concentration followed by temperature for both alkali and acid leaching play important role in ash-reduction. The maximum ash reduction of 73.84%, 71.88% and 49.40% were obtained at the working conditions: (125-63 μm particle-size, 55 g/ton diesel-oil/collector, and 370 g/ton n-octanol/frother), (1 mol/dm3 NaOH, 220 oC and 60 minutes), and (1 mol/dm3 HCl, 80 oC and 3 hours) for flotation, alkali and acid leaching, respectively. The result from proximate-analysis shows that the raw-samples of coal contain 10.67% moisture, 33.73% ash, 30.34% volatile matter, 25.26% fixed-carbon, and 0.67% sulfur with 3,643.08 kcal/kg calorific value. The results for the treated coal sample show that the ash content was 8.92%, 2.51% and 1.27%; and sulfur percentage was 0.45%, 0.38% and 0.37% with 4,996.20 kcal/kg, 6,195.29 kcal/kg and 7,124.58 kcal/kg of calorific values for flotation-concentrate, alkali-leached and acid-leached coal samples, respectively. The results of this study confirm that the treated-samples of coal resulted in higher-heating-values and fixed-carbon, and lower-ash and sulfur-contents as_compared to the_raw_sample. Hence, with the determined optimum conditions, applying froth-flotation followed by sequential alkali/acid leaching is effective to increase the heating-values and upgrade the energy/quality of the sample coal, being as suitable energy source for industries like cement_and_steel.
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    Quality Characterization of Haricot Bean (Phaseolus Vulgaris L.) and Pumpkin Flours for the Development of Functional Kemesha, A Traditional Food in Ethiopia
    (Addis Ababa University, 2023-06) Derese Wodajo; Shimelis Admassu (Prof.)
    Traditional foods are significant in using local resources and are generally more available to rural communities. Kemesha is a traditional food of the Arsi Zones in Ethiopia, made by mixing common wheat flour (Triticum aestivum) and water, followed by sheeting, rolling, cutting, and sun-drying. However, the process is labor-intensive, extremely sluggish, and produces uneven quality and unhygienic products. The study aimed to standardize, optimize and characterize Kemesha while enhancing its nutritional and functional qualities to increase its appeal. Initially, documenting the existing Kemesha-making process, then standardizing Kemesha based on the sensory acceptability test and quality characterization. The compositional analysis showed that standardized Kemesha contains 9.22, 2.13, 8.90, 1.25, 2.41, and 76.08 g/100 g moisture, fat, protein, crude fibre, and ash content, respectively. Findings on textural properties also revealed that the firmness, springiness, cohesiveness, adhesiveness, and chewiness were 904.94 g, 0.28, 0.45 24.94 g*s, and 114.40 g, respectively. Standardized Kemesha has a low cooking loss (7.25%) and a high water absorption percentage (180.62%). Wheat-based food is high in carbohydrates but low in other vital nutrients, including protein, fibre, and bioactive ingredients, which frequently cause nutrient imbalances among consumers. However, there has been a noticeable rise recently in the desire for a balanced diet that contains all the essential components, has fewer calories, and offers health benefits as a functional food. So, the study’s goal was also to use characterized haricot bean and pumpkin flour as raw materials to increase the nutritional value and functionality of standardized Kemesha, thereby increasing its acceptability. It is crucial to conduct a thorough analysis to preserve the bioactive components and other nutritional values of the crops while minimizing their anti-nutritional values to produce the value-added food product Kemesha from dry beans and pumpkin flour. Before processing first, we assessed the impact of bean variety on the geometric characteristics and mass-volume-area attributes of four improved haricot bean varieties. The moisture content, 1000 seed weight, and true density varied significantly (p < 0.05) in the range of 9 to 11.28%, 199.9 to 529.93 g, and 1127.52 to 1212.40 kg.m-3; also, the dimensional properties of the improved haricot bean were significant (p < 0.05) among the varieties indicating that these would require some variation in the processing equipment design. Then, the impacts of soaking (for 24 hours), germination (for 96 hours), autoclaving (at 121°C for 30 minutes), and germination followed by autoclaving processing methods were assessed on the physicochemical properties of haricot bean flours. The beans flour composition varied significantly from 8.05 to 9.72%, 23.11 to 27.96 %, 1.33 to 2.87 %, 3.82 to 5.97 %, 3.45 to 5.52%, and 51.79 to 57.14%, respectively for moisture, crude protein, crude fat, crude fibre, ash, and carbohydrate contents. Germinated flour demonstrated a notable degree of DPPH scavenging activity (EC50) and a range of total flavonoids and phenols (2.79 to 3.69 mg QE/g and 0.72 to 1.04 mg GAE/g, respectively). The germination process decreases flour’s thermal and pasting properties, which could enhance its better utilization in the food industry due to the loosening structure caused by increased amylase activity. Additionally, sprouted flour has the potential to be employed in a number of culinary products as a functional ingredient and nutritional supplement. During pumpkin processing, pre-drying methods are essential to prevent the effect of high temperatures involved in conventional air drying, which degrade the color, nutritional value, and bioactive component of pumpkin flour and boost drying effectiveness. In these experiments, the pre-drying methods comprised ultrasonication for 10, 20, or 30 minutes, microwave blanching for 6 minutes at 300 W, and combined ultrasound followed by microwave blanching. The proportions in terms of moisture, ash, crude fat, crude protein, crude fibre, and carbs in the pumpkin flours were 7.57 to 8.23 %, 5.73 to 6.57 %, 1.17 to 1.85 %, 8.72 to 11.32 %, 10.92 to 13.11 %, and 61.47 to 64.23 %, respectively. In comparison to other pre-drying treatments, 20UM was the optimum method in terms of reducing drying time (32.78 %), preserving a color change (9.06), total phenol (6.31-229.99 mgGAE/g), total flavonoid (1.97-135.22 mgQE/g), total carotenoid (131.50-9.84 g/g), and DPPH activities during processing. In order to expand the potential applications of pumpkin flour in functional food products, the fibre and bioactive components of the flour were enhanced through particle size reduction. After pre-drying treatment, the pumpkin flour ground to a particle size of < 75 μm exhibited the highest concentrations of total phenol, flavonoids, and carotenoids (6.52±0.59 mg GAE/g, 1.92±0.85 mg CE/g, and 139.79±0.96 μg/g). However, the moisture content and color brightness showed a decline after pretreatment and improved when the particle size was reduced.The maximum pasting viscosities were found in the pretreated fine-milled flour (20UM1), whereas the lowest viscosities were found in the untreated coarse-milled flour (CON3). Generally, 20UM1 flour has outstanding composition, thermal, functional, and structural features compared to other flours, making it a superb component to increase the important ingredients in various food formulations. The production of Kemesha, which included common wheat flour, haricot beans, pumpkin flour, and carboxymethyl cellulose, was optimized in this study using a D-optimal approach to determine the most significant factors. The outcomes of numerical optimization and model validation showed that the combination of 63.00 g of common wheat flour, 19.01g of germinated haricot bean flour, 14.51 g of ultrasonically fine-milled pumpkin flour, and 3.48 g of carboxymethyl cellulose per 100 g of flour composition with 0.596 desirability’s was viable for the preparation of kemesha. The total phenolic, flavonoid, and carotenoid content of the optimized functional Kemesha was 7.47, 3.67, and 149.20 times greater than that of the control Kemesha. The increase in these phytochemicals signifies that this Kemesha may offer the user the natural health benefits of pumpkin and germinated haricot beans. The study found that the addition of CMC, finely ground ultrasonicated pumpkin flour, and germinated haricot bean flour has improved the nutritional value, texture, cooking properties, and sensory characteristics of Kemesha. Furthermore, the optimized Kemesha exhibited improved cooking loss (4.95%) and water absorption (220.68%) compared to the standardized control Kemesha.
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    Synthesis, Parametric Optimization and Characterization of Gum Arabic Powder
    (Addis Ababa University, 2023-10) Lubaba Moshe; Anuradha Jabasingh (PhD)
    Gum Arabic, or acacia gum, is the resin exuded by Acacia Senegal trees. It also has several industrial applications. But these, natural gum Arabic exudates are contaminated by sand, dirt, insects, pieces of bark and leaves, bacteria and so forth. This condition makes the gum exudes to be unsuitable for the immediate use. Therefore, finding the purification process of gum Arabic is the first and the most important step. This mechanism improves the quality of the product and makes direct immediate use of acacia gum in the industry. The core objective of this research work was to produce purified, dried, instant gum Arabic powder and develop optimization of the freeze drying operating conditions. Finally characterization of the powder was carried out and yield was determined. To conduct this study, impurities of gum exudates were removed by three major separation processes. This is carried out by dry cleaning, aqueous solution cleaning and freeze drying process respectively. In this study, different concentrations of dissolved gum Arabic solution and drying temperature of 25%w/v to 33.33%w/v and -50°C to -30°C as maximum and minimum values were used respectively. Optimization for these drying parameters was carried out by the central composite design, using the Response Surface Methodology (Design experiment software version 11). During the experiment, it was observed that the acacia gum yield at different runs ranged from 96.35g to 214.1g and the moisture content ranged from 6.07% to 13.9%. An optimum acacia gum yield of 136.12g and minimum moisture content 10.16% were observed at -31.8°C temperature and 33.33% (w/v) feed solution concentration. The two main factors considered for this research study, namely feedstock concentration and drying temperature had a statistically significant effect (p<0.05) on both responses named the powder yield and moisture content. After the synthesis, the product (acacia gum powder) was characterized using FTIR spectroscopy, NMR Spectroscopy, TGA Analysis and DSC Thermogravimetric Analysis.
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    Parametric Optimization for Adsorptive Removal of Lead Ions by Magnetic Activated Carbon Prepared from Corn Cob
    (Addis Ababa University, 2022-09) Yoktan Seifu; Abubeker Yimam (PhD)
    Water pollution has been a major challenge to environmental engineers today due to the release of toxic heavy metals from various industries. Among various heavy metals, Lead ion (Pb2+) is considered as highly toxic, and causes various health disorders. Different sources of Lead ion (Pb2+) pollution include effluents from mining, electroplating, painting, and electroplating industries. Among various technologies, adsorptive removal of Lead ion (Pb2+) by using different adsorbents is more promising and economical. Among various adsorbents used, Magnetic activated carbon (MAC) is well known for its high adsorption capacity due to its large surface area, and pore volume. Corn Cob is lingo-cellulosic material that was selected as the precursor for the preparation of Magnetic Activated Carbon. Activated carbon was prepared through prior chemical activation using phosphoric acid following embedding of the prepared Activated Carbon by Iron oxide. The effect of various process parameters such as carbonization temperature, and Carbonization time were investigated on Lead ion (Pb2+) removal efficiency. The results indicated that BET surface area of 504 m2/ g. at approximately 610°C carbonization temperature, and 3hr. of carbonization time was measured. Effect of adsorbent dosage, pH, and initial Pb2+ concentration were studied. Optimum removal of Lead ion was recorded at 0.6 g. adsorbent dosage, pH of 5, and initial Lead ion concentration of 75 mg /l w ith Lead ion removal efficiency of 92.86% and desirability of 0.844 Kinetics and isotherm studies indicated that the adsorption mechanism of Corn Cob based Magnetic Activated Carbon follows pseudo second order (R2=0.9902) while Freundlich isotherm model well fitted the adsorption data with R2=0.9841. In terms of regeneration, adsorption efficiency of CCMAC for six cycles decreased from 89.34 to 34.68%. Corn Cob can be a good precursor for Magnetic Activated Carbon preparation and can be used to remove Pb2+ from wastewater.
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    Development of Inoculated Fermentation System for the Production of Ethiopian Honey Wine, Tej, with Suspended Mixed Starter Culture
    (Addis Ababa University, 2022-06) Eskindir Getachew; Shimelis Admassu (Prof.); Hundessa Dessalegn (PhD)
    Traditional alcoholic beverages are widely produced and consumed in Ethiopia. Tej, Ethiopian honey wine, is one of Ethiopia's most popular spontaneously fermented traditional alcoholic beverages, usually made from honey and gesho (Rhamnus prinoides). However, this spontaneous way of fermentation increases the likelihood occurrence of suck and/or slow fermentation, making the process difficult to predict, control, and correct. Furthermore, it may also cause the product to have off flavor and inconsistent quality. As a result, the overall goal of this research is to create a direct fermentation system for Tej fermentation system, which is the assumed solution to the aforementioned problems. To achieve this goal, a physico-chemical and microbial ecological investigation, microbial isolation and strain selection, and kinetic study were carried out. Based on the honey production potential, Tej consumption culture, accessibility, and suitability for sample collection, study area for this research was selected to be Addis Ababa (AA), Debre Markos (DM), and Bahir Dar (BD), Ethiopia. The physicochemical properties of Tej samples collected from the aforementioned areas varied significantly from household to household and location to location. The alcohol and sugar contents ranged from 6.36 to 11.34 g/100 mL and 0.37 to 31.6 g/L, respectively. However, the microbial profiles were dominated by a few fermentative microorganisms. The bacterial community structure of Tej samples was dominated by the genera Lactobacillus (53.15%) and Zymomonas (38.41%). Similarly, the fungal community was exclusively dominated by the genus Saccharomyces (99.66%). Moreover, the microbial communities shifted to Lactobacillus and Saccharomyces dominance as Tej fermentation period progressed to the end. Furthermore, throughout these spontaneous fermentation period, the number of bacterial gene copies was half that of fungal gene copy numbers. After the intensive purposeoriented screening and genotypic identification the isolated strains were Saccharomyces cerevisiae, Pichia fermentans, Wickerhamomyces anomalus, Lactobacillus hilgardii, Lactobacillus paracasei, and Lactobacillus parabuchneri. These isolated microbial strains were then used to ferment honeymust in various combinations. The more mixed the microbial strains are, the more the fermented product resembles the control sample in terms of physicochemical properties and volatile compound profile. Moreover, to reduce the possibility of sluggish and stuck fermentation, the medium was supplemented by diammonium phosphate (DAP). Higher fermentation rate was observed for the medium supplemented with the nitrogen concentration greater than 140 mg/L. A predictive kinetic model for microbial growth, substrate utilization, and product formation rate was developed using two substrate limitation (Monod and Teissier) and product inhibition (Ghose and Tyagi) models.After simulation and parameter estimation, the Teissier model adequately described yeast assimilated nitrogen (YAN) utilization and ethanol production. Whereas Monod-Cheirsilp and Monod kinetic modes effectively described lactic acid bacteria (LAB) growth and sugar consumption rates. In general, the microbiological ecology analysis, isolation of dominant strains, and design of fermenting medium performed in this study yielded promising results for the modernization of Ethiopian honey wine, Tej. However, much more input from future research findings is required for the complete process upgrade, particularly in the areas of fermentation parameter optimization.
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    Catalytic Conversion of Sugarcane Bagasse into Furfural
    (Addis Ababa University, 2022-04) Negesso, Wakushie; Belay, Woldeyes (Prof.); Hundessa, Dessalegn (PhD)
    The production of furfural, high-value-added platform chemicals, is hampered by the typical drawbacks of homogeneous acid catalysts, such as difficulty in separating the catalyst from the reaction mixture. As a result, developing a heterogeneous catalyst to overcome the limitations of current commercial processes is highly desirable. The carbon-based catalysts were synthesized by carbonizing and functionalizing teff-straw as a carbon precursor in concentrated sulfuric acid simultaneously and showed the ability to dehydrate xylan/xylose to generate furfural. As shown by FTIR, the catalyst comprises functional groups such as –SO 3 iv H, –COOH, and –OH, which are extremely beneficial to catalytic performance. The elemental analysis of the samples also confirmed the successful attachment of sulfur to the carbon structure and XRD results, the diffraction peak at 2 from 15 to 30 o , depicted the amorphous nature of the catalyst prepared. Experimental runs, catalytic and thermal, were carried out over the prepared catalyst to investigate catalytic activities such as overall conversion, selectivity, and catalyst stability. Conversion of xylose to furfural was investigated using a Teff straw-based sulfonated catalyst (TSSC) in water/toluene as an extraction medium. A maximum furfural yield of 62.50% was obtained at 190°C for 20 min with 0.2g solid acid. Besides, hydrolysis of sugarcane bagasse to xylose using a dilute sulfuric acid catalyst was investigated. An optimum xylose yield of roughly 0.18g/g of dry bagasse was obtained in 32 minutes with 0.77% sulfuric acid at 143 °C. Model-Based Calibration Toolbox in MATLAB software was used for the design of experiments, statistical modeling, and optimization. Although the combined effect of temperature, acid concentration, and time was positive towards the formation of glucose and furfural, harsher treatment conditions showed negative effects on the yield of xylose. The experimental data were analyzed to create a kinetic model for lignocellulosic biomass conversion to furfural using the synthesized catalyst. The kinetic model for the dehydration of xylose to furfural was developed using experimental data obtained based on the Central composite design. The well-evaluated kinetic model matched well with the experimental data and kinetic parameters. The thermodynamic analysis suggested that the presence of toluene, in the reaction system, as a solvent for instantaneous extraction of furfural enhanced furfural production while decreasing degradation rate as compared to water-only system.
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    Pulp Yield Determination of Ethiopian Highland Bamboo (Yushania Alpina) By Soda/Aq Catalytic Pulping
    (Addis Ababa University, 2021-06) Andualem, Legesse
    The ever growing demand for pulp, paper and paper products in Ethiopia on one hand and the continually increasing price of woody pulp on the other hand necessitates looking for an alternative source of pulp. The country is endowed with a huge potential of naturally growing bamboo and accessible and suitable land for its possible plantation. Bamboo grows rapidly, is easy to spread, and is highly productive and easy and suitable for harvest. Looking for an environmentally friendly pulping technique for appropriate utilization of such resource is essential. This research investigated the pulp yield of Ethiopian highland bamboo (Yushania alpina) using soda-Anthraquinone (AQ) catalytic pulping and characterized the paper made of such pulp. Samples of bamboo have been harvested from Western Ethiopia Jimma area, air and oven dried, milled, and the bamboo chips were cooked (pulped) using autoclave digester with 10%,15%, and 20% alkali charge; at cooking temperatures of 140, 160 and 1800C for 120, 150 and 180 minutes. The optimum operating condition that maximizes the pulp yield and minimizes the kappa number was obtained at active alkali concentration of 15.8%, cooking temperature of 158.6°C and cooking time of 156 minutes to be 50.7% and 13.4 respectively. This optimum condition was used to make laboratory scale paper and its mechanical properties were assessed. The tensile, bursting and tearing indexes were found to be 30.2Nm/g, 1.602kPam2/g and 12.5mNm2/g respectively. These values indicate that quality paper comparable to the one obtained from softwood pulp, with desirable properties can be obtained from Ethiopian highland bamboo with an environmentally friendly pulping procedure of soda – AQ pulping.
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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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    Production, Characterization and Optimization of Starch Based Biodegradable Bioplastic from Waste Potato Peel with the Reinforcement of False banana (Ensete ventricosum) Fiber
    (Addis Ababa University, 2021-09) Tarekegn, Yohannes; Beteley, Tekola (PhD)
    Recently, environmental pollution from petroleum-based synthetic plastics become the headache of the world. Their greatest problem is that they are not biodegradable. To combat this serious issue producing biodegradable bioplastics is becoming the best solution ever. In this study, potato peel starch (PPS) based bioplastic film was developed. The proximate composition of potato peel was found to be 8.13, 4.89, 10.13, 0.27, 9.52 and 51.16 % by dry weight basis for moisture, ash, crude protein, crude fat, crude fiber and starch content, respectively. PPS contained 18.6, 0.01, 0.53, 0.00 and 27.93 % for moisture, ash, protein, fat and amylose, correspondingly. A bioplastic film was prepared by a method of gelatin casting, in which the effect of 13.33, 23.33 and 33.33 % v/w (HCl or glycerol to PPS ratio) concentration of HCl and glycerol as well as drying temperature (45oC, 55oC and 65oC) was studied. The experiment was designed and optimized by a three-variable, three-level Box–Behnken design using Response Surface Methodology (Design Expert® software version 13.0.1). The ANOVA analysis showed that the model is significant with P<0.0001. The optimum values of the influencing factors were found to be HCl concentration 23.33 %v/w, glycerol 20 %v/w and drying temperature of 48oC. Under optimal conditions a bioplastic film with tensile strength of 6.449MPa, percent elongation at break of 19.87%, biodegradability of 83.92 and water absorption of 59.94 % was synthesized with insignificant difference from model predicted result. A bioplastic film reinforced with 6% w/w False banana fiber has shown remarkably enhanced maximum tensile strength recorded to be 8.878MPa. Furthermore, analysis of FTIR, XRD and surface morphology were conducted. The produced bioplastic film had sufficient physicochemical properties confirming the usage of waste potato peel as a source of starch for the synthesis of biodegradable bioplastics that can substitute conventional plastics.
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    Production of Eco Bricks Using Tannery Sludge as a Partial Substitute for Clay
    (Addis Ababa University, 2021-10) Haregewoin, Nida; Abubeker, Yimam (PhD); Lemma, Dendena (PhD) Co-Advisor
    Tannery sludge is an unavoidable by-product of waste water treatment plants of leather industries and with no safe disposal options; it has the potential to become a significant environmental burden for Ethiopia in the future. Presently, the sludge generated from the leather industries will be land filled without any kind of treatment. Because sludge contains a high concentration of organic and inorganic components, including heavy metals, its accumulation is a burden on the industry and has negative consequences for the environment and human health. As a result, an alternative sludge disposal strategy is required. The major goal of this research was to see if using TS with certain proportions in the manufacturing of bricks may be a viable alternative to natural clay. In laboratory-controlled conditions, clay bricks were made with various proportions of sludge (10%, 15%, 20%, and 25% by weight) with firing temperature of 800℃, 900℃ and 1000℃and its potential as a construction material was evaluated based on its Compressive strength, water absorption, weight loss on ignition, bulk density, firing shrinkage, electrical conductivity and heavy metal leaching properties. As a result, increasing the sludge content in bricks resulted in a decrease in compressive strength and increase in water absorption. When TS content was increased from 0% to 25%, the compressive strength of TS bricks decreased significantly, from 30.24 MPa to 20.15 MPa. Water absorption increased from7.03% to 16.03% when sludge proportion was increased from 0% to 25% at firing temperature of 1000°C. In addition, total shrinkage and weight loss in burning were compared to raw brick, revealing that total shrinkage did not differ significantly, while weight loss in burning varied from 12.25 % to 30.8 % in raw brick to 25% TS brick at firing temperature of 1000°C. Furthermore, the sludge altered up to a 15% mixing ratio demonstrates minimal heavy metal leachability as analyzed by TCLP and is compatible with the USEPA standard. As a result of the research, tannery sludge has the potential to be used in the production of sludge bricks with sludge proportion of 10% to 15% and firing temperature of 900°C to1000°C.
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    Synthesis of Bamboo Derived Sulfonated Solid Acid Catalyst for the Hydrolysis of Cellulose and Epoxidation of Cottonseed Oil
    (Addis Ababa University, 2021-07) Elyas, Belay; Berehanu, Assefa (PhD); Beteley, Tekola (PhD); Cabello, Francisco Medina (Prof)
    Nowadays the use of biomass derived sulfonated catalyst in the place of mineral acid becomes a hot research spot. Biomass derived catalysts own multiple quality regards to environment, reuse of catalyst and in facilitating down-stream process. In this work, bamboo derived sulfonated catalysts were prepared with consecutive carbonization and sulfonation process. The synthesized catalysts were characterized and its activity was evaluated through cellulose hydrolysis and epoxidation of cottonseed oil. The catalyst was prepared through carbonization of bamboo saw-dust at three different temperatures; 400 °C, 450 °C, and 500 °C and then sulfonated using concentrated sulfuric acid (> 96 %), at 150 °C temperature for 15 h. The synthesized catalyst was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), elemental analysis, thermogravimetric analysis (TGA) coupled with mass spectrophotometer, ammonia temperature-programmed desorption (TPD), total acid content (titration method), and surface area analyzer (surface area, total pore volume, and pore size). The FTIR spectroscopy result of the catalyst indicated a sulfonate group (-SO3H) which was not found in the respective char of the catalyst. Moreover, elemental analysis of the catalyst showed significant amount of elemental sulfur in the catalyst. The acid content analysis revealed maximum amount of acid density (0.58 mmol/g) in the catalyst which its char was prepared at 500°C. The catalyst activity was primarily studied in the hydrolysis of crystalline cellulose. The hydrolysis was performed using autoclave reactor with varying hydrolysis temperature and time. The final product for total reducing sugars were analyzed using dinitro salicylic acid (DNS) method. From this study, the highest of total reducing sugar yield was found (4.0 %) at a temperature of 150 °C over a hydrolysis period of 8 h. The reuse capacity of the catalyst was tested in three successive hydrolysis reactions and the results showed that the catalyst maintain its activity in each hydrolysis reaction. The catalyst activity was further studied using microwave reactor in the hydrolysis of crystalline cellulose. The converted cellulose and glucose yield after the hydrolysis were analyzed by total organic carbon (TOC) analyzer and high performance liquid chromatography (HPLC). The combined effects of the synthesized catalyst and microwave reactor in crystalline cellulose hydrolysis resulted higher glucose yield. The effects of the synthesized catalyst on the hydrolysis of crystalline cellulose was studied with varying operating temperature and time. The maximum yield of glucose was found 43.5 % at a reaction temperature of 180°C and 60 minute of reaction time. Similar conversion and glucose yield were attained in second run showing the reusable potential of the synthesized catalyst. Cellulose hydrolysis operating condition optimization was performed using response surface methodology. Three-factor and three- level Box-Behnken design was employed to study the effects of hydrolysis temperature, hydrolysis time and catalyst to substrate ratio on total converted cellulose and glucose yield. Additionally, prior to the hydrolysis took place, the crystalline cellulose was milled using vibrational mill. The XRD result of the milled cellulose showed that vibrational milling could decrease the crystallinity index from 96.4 % to 59.55 % and the crystallite size from 3.61 nm to 2.09 nm within 60 min milling time. The result of optimization revealed both response best explained in quadratic model. The respective analysis of variance (ANOVA) showed that the proposed quadratic models could be used to navigate the design space. The optimum hydrolysis conditions were found out to be hydrolysis temperature of 175 °C, hydrolysis time of 74 minutes and catalyst to substrate ratio of 1.25 g/g. Under these conditions the total amount of converted cellulose and glucose yield were 79.4% and 61.1%, respectively. Model validation was performed at the given operating conditions. A cellulose conversion of 78.5 ± 0.75 and glucose yield of 60.6 ± 0.4 were found. These results indicated that the predicted values were in a good agreement with the experimental results. In addition to running cellulose hydrolysis tests, the synthesized catalyst activity was tested in the epoxidation of cottonseed oil. Bamboo derived sulfonated catalyst (BSC) was used for all epoxidation reactions. The effects operating conditions such as: catalyst loading, epoxidation temperature, and amount of peroxide on the oxirane content were studied. In general, the results of relative percentage conversion of oxirane indicated that the given operating conditions significantly affected it. On the other hand, the maximum amount of relative percentage conversion of oxirane content 36.8 % was obtained at temperature of 60 °C, reaction time of 8 h, catalyst loading of 15 %, and mole ratio of hydrogen peroxide to double bond (DB) of the oil was 2.
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    Cultivation of Microalgae for Biofuel Production: Coupling With Sugar Factories
    (Addis Ababa University, 2021-06) Deribew, Tefera; Abubeker, Yimam (PhD)
    Due to many important characteristics of microalgae including high oil content, ability to overcome harsh conditions and high photosynthetic efficiency the production of biofuels from algal biomass has gained interest. However, large scale production of biofuel from microalgae is still uncertain primarily due to a lack of feasibility of the process and that it proves to be capital and energy-intensive. Therefore, an integration of microalgal cultivation with other processes for achieving an inexpensive nutrient and a reduced energy use has paramount importance. Coupling of microalgal biofuel production with other process such as wastewater treatment, industrial and power plants has been found helpful in increasing feasibility of the process. The main objective of the present study was to evaluate the potential of sugar factories’ wastes to support the growth of microalgae for biofuel production. A case study approach was followed considering a sugar factory, Metahara sugar factory, with annexed distillery plant. Two scenarios were considered. In the first scenario the wastewater from the sugar mill was used as the only nutrient source for the growth of the microalgae. In the second scenario the vinasse from the ethanol production plant was used as an additional nutrient source along with the wastewater from the sugar mill. Economic feasibility was also performed for the second scenario. The first scenario of the study shows that 12 mg of total nitrogen (TN) and 7.4 mg of total phosphorus (TP) per liter of wastewater could be transferred to algal growth ponds, and approximately 121 tons/year algal biomass would be produced from the integrated process. By applying all the underlined assumptions reductions of COD (mg O2/L) from 2200 to 447, BOD5 (mg O2/L) from 1200 to 207, total nitrogen, TN (mg/L) from 15 to 0.6 and total phosphorus, TP (mg/L) from 10 to 1.5 were found from the coupled process. The results from second scenario of the study showed three products: biodiesel production of 188 ton/year, biogas production of 2011000 m3/year, and bio-fertilizer production of 42 tons/year. Economic evaluation of the coupled process for the biofuel production showed that in order for the biodiesel from microalgae to be competitive with the current petroleum its minimum selling price (MBSP) needs to be reduced at least by half. Sensitivity analysis on the MBSP shows that oil content of the microalgae and nitrogen content in the waste effluents are the two dominant factors which significantly affect the feasibility of the process. This study investigated the potential of a future possible bio-refinery and environmental pollution reduction concept by coupling microalgae biomass production with sugarcane-processing factory wastes and by-products. It was found that the factory wastes and by-products have a significant potential for a viable biofuel production from microalgae. Study on the biology of the microalgae to get a robust strain with high oil content, the development of energy-efficient and cost-effective harvesting technology, and study on the development of selective, sensitive and inexpensive control methods, etc. are essential future research works for boosting viability of biofuel production from microalgae.
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    Synthesis and Characterization of Α-Ferric Oxide from Local Iron Ore in Ethiopia
    (Addis Ababa University, 2021-10) Dawit, Dilallah; Beteley, Tekola (PhD)
    Ethiopia has a huge deposits of iron ore and 𝛼-ferric oxide, (𝛼-Fe2O3) has received great interest and extensively used in agriculture, chemical industries, paint industries, as catalysts, magnetic materials, gas sensors, lithium-ion batteries and waste water treatment plants. Therefore, this study is to synthesize 𝛼-ferric oxide from local iron ore in Ethiopia. Iron ore samples has been studied from two different regions (Sekota and Axum) and characterized in geological survey of Ethiopia laboratory with the grade of 46.56% and 65.81% of iron oxide composition found from Sekota and Axum respectively. The sample from Axum was reacted with hydrochloric acid and ammonium hydroxide by fluctuating three process variables: particle size, calcination temperature and calcination time. The effect of these different particle size (0.125mm – 2mm), calcination temperature (500 – 600 °C) and calcination time (90 – 150 minutes) towards the yield of 𝛼-ferric oxide, (𝛼-Fe2O3) synthesis were investigated by using design of expert (DOE) version 12.0 software and Box-Behnken design method. Based on analysis of variance (ANOVA), the determination coefficient, R2 obtained was 0.9878. Optimization processing condition that synthesizes highest yield of 77.103 % was at particle size (<0.125mm), calcination temperature (500 °C) and calcination time, (126.73 minutes). Characterization of 𝛼-ferric oxide, (𝛼-Fe2O3) powder samples were investigated by means of numerous characterization methods like; X-Ray Diffractometer (XRD), Fourier Transform Infrared (FTIR) and Major and minor oxide analysis. From FTIR spectrum Iron-oxide group (Fe-O) and atmospheric carbon dioxide (CO2) were found. The characteristic peak occurring at 2θ = 33.4° indicated presence of 𝛼-Fe2O3 in the samples with 14 nm particle size. The synthesized particles confirmed 91.56% of Fe2O3 by Major and minor oxide analysis which is acceptable purity. Last of all, From the result it is conceivable to say that producing of such chemical from local raw materials can help as upbringing idea for next studies.