School of Chemical and Bio Engineering

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Browsing School of Chemical and Bio Engineering by Subject "Activated carbon"

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    Preparation and Characterization of Activated Carbon from Flower Waste Biomass for Methylene blue Removal
    (Addis Ababa University, 2019-11) Getu, Maru; Sintayehu, Nibret (PhD)
    Activated carbon (AC) can be used as an adsorbent to remove pollutants from waste water streams. 520 kg flower biomass waste is generated daily at a single floriculture industry in Ethiopia. Despite AC has been produced from different lignocellulosic biomass waste, utilizing Flower waste biomass (FWB) as a precursor to produce AC has an advantage of being new raw material, easily available, renewable precursor, and can be a way of reducing environmental pollution. This study presents synthesis of AC from FWB by chemical activation method using ZnCl2 and removal of methylene blue (MB) using the as-prepared AC. The parameters in the study were impregnation ratio, carbonization temperature, and carbonization time. Higher BET surface area of 750 m 2 -1 g , pore volume of 1.91 cm 3 -1 g and pore diameter of 1.89 nm was obtained at 1:1 impregnation ratio, ° 500 C carbonization temperature, and 1 hr of carbonization time. Effect of adsorption dosage, PH, initial dye concentration, and contact time on percentage removal of MB were studied. Maximum removal of MB was recorded at 0.05 g adsorbent dosage, 60 min contact time, PH of 10, and initial dye concentration of 10 mg L -1 . Kinetics and isotherm studies showed that the adsorption mechanism of MB using FWB based AC follows pseudo second order while both Langmuir and Freundlich model well fitted the adsorption data with maximum removal efficiency of 94.2% and adsorption capacity of 22.39 mg g -1 . FWB can be a good precursor for AC production and can be used to remove MB from wastewater.
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    Preparation, Characterization and Application of Coffee Husk Based Activated Carbon for Adsorption of Cr(VI) From Aqueous Solution
    (Addis Ababa University, 2015-07) Teshome, Awugchew; Jabasingh, Anuradha(Perofessor)
    This research proposed coffee husk as a low-cost material for production of activated carbon and investigated its application for adsorption of Cr(VI) from aqueous solution. The initial work involved, the optimization of process parameters involved in preparation of activated carbon by chemical activation using H3PO4. Four parameters such as concentration of H3PO4, impregnation ratio, carbonization temperature and holding time were optimized by Response Surface Method (RSM) using Box-Behnken design technique and the produced activated carbon applied for Cr(VI) adsorption. RSM revealed that the effect of on operational parameters on Iodine number and yield of coffee husk activated carbon was best described by quadratic polynomial model. Analysis of variance (ANOVA) revealed a good agreement between experimental and predicted value. The characterization result showed that the coffee husk activated carbon has good properties and compared favourably with other reference activated carbons. FTIR test and point of zero charge pH, showed the presence of acidic functional groups on surface. Cr(VI) adsorption shows that the system was pH dependent. The linear regression analysis of kinetic data confirmed that pseudo-second order rate expression best fitted for all temperature. Langmuir equation was found to fit the equilibrium data for Cr(VI) adsorption with monolayer capacity of 78.74, 84.03 and 92.59 mg/g at 25, 35 and 45oC respectively. Thermodynamic analysis asserted endothermic and spontaneous nature of the system with involvement of chemical adsorption process. Key word; Activated carbon, Coffee husk, process optimization, Cr(VI) adsorption