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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/2679

Authors: Anteneh, Mesfin
Advisors: Dr. Tassisa Kaba
Copyright: May-2009
Date Added: 6-May-2012
Publisher: AAU
Abstract: Waste brewery yeast has been used for biosorption of lead and nickel. The dried, ground and protonated yeast has been contacted with Lead (II) and Nickel (II) solutions so as to investigate impact of PH, Contact time, presence of co-ion, and study equilibrium and kinetics of the sorption process. PH has been found to affect lead sorption considerably in the test range of 3 to 6 where the optimum sorption capacity was found to be PH of 3 to 4. Nickel sorption remained almost unaffected in the PH range 3-7. The higher proportion of the heavy metal ion has been sorbed during 5 to 10 minutes of contacting and equilibrium has been reached within 60 minutes where the optimum sorption time is 30min. Langmuir and Freundlich adsorption models have been used in the equilibrium study in order to fit the equilibrium data procured after 24 hours of contacting. As to the Langmuir isotherm model, maximum adsorption capacity qmax and affinity,b were found to be 312.5 mg/g and 0.237 for lead and 526.3 mg/g and 0.005 for nickel respectively. For Freundlich model Kf and n have been determined to be 0.946 and 0.971 for lead and 0.239 and 1.133 for nickel respectively. Concerning the kinetics of the metal uptake process, rate of metal uptake has been determined for varying metal dose in the range of 10-200mg/l and yeast dose in the range of 0.5 – 4 g/l. the curve fitted better to freundlich model than Langmuir model. The equilibrium uptake capacity (qe) rate constant(k) and initial rate of uptake(h) were calculated for metal doses ranging from 10- 200 mg/l and yeast biomass dose of 0.5-4 g/l. qe shows an increasing trend for increasing metals dose and is inversely related to yeast dose, similarly, K and h also show increasing trend for metal dose. As to the co-ion tests conducted sorption of lead decreased from 576mg/g to 444.5mg/g when nickel concentration was increased from 50 mg/l to 700 mg/l. But to the contrary increasing dose of lead did not affect the sorption of nickel. Based on recovery tests, he recoverability of lead (80%) was significantly higher than that of nickel (38%).
URI: http://hdl.handle.net/123456789/2679
Appears in:Thesis - Chemical Engineering

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