Center for Materials Engineering

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Browsing Center for Materials Engineering by Author "Dawit, Ayana (PhD)"

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    Synthesis and Characterization of Cellulose-based Aerogel from Mixed Organic Solid Wastes
    (Addis Ababa University, 2020-10) Kidist, Worku; Dawit, Ayana (PhD)
    Cellulose-based aerogels are materials that are produced from cellulose, which is the most abundantly available natural polymer. Like other aerogels, cellulose-based aerogels have low density and highly porous structure made from interconnected network of cellulose fibers. Those properties of cellulose-based aerogels prepared from easily available raw materials, that make it potential alternative material applicable for the removal of oil and organic solvents. The direct discharge of oil and organic solvent containing waste water damages the marine ecological environment and intoxicate life thereby, imposing immediate and longtime damages. In this work, cellulose-based aerogels were synthesized by mixing cellulose-rich organic solid waste materials. Cellulose-based aerogels were produced combining textile cotton fabric (100 % cotton), waste paper, and waste banana peel without pretreatment. Sol-gel process followed by freeze drying was executed to successfully fabricate the cellulose-based aerogel. Precooled NaOH/urea solution was used at standard NaOH/Urea/water (7:12:81) ratio for cellulose dissolution by varying precursor/solvent ratio and dissolution time. Further, hydrophobic modification using carbon nanoparticles/acetone solution was performed to the cellulose-based aerogel with the best characteristic properties. This gave the aerogel an oil/organic solvent selectivity property during waste water treatment. A cellulose-based aerogel with the lowest density of 0.127 g/cm3 that showed a macroporous structure with 91.5 % porosity and specific surface area of 192.24 m2/g. Sorption capacity and removal efficiency tests were done for cooking oil, engine/motor oil, ethanol, and benzene. Accordingly, sorption capacities of 15.74, 13.81, 13.98, and 13.98 g/g were recorded respectively. After the removal tests the efficiency of cellulose-based aerogels were found to be 80.89 % for cooking oil, 77.2 % for engine/motor oil, 76.48 % for ethanol, and 74.1 % for benzene. The aerogel was recycled to be reused a number of times in which it was able to remove more than 50 % of contaminants up to the third cycle. Hence, the characteristics and pollutant removal performance of cellulose-based aerogel make it a potential candidate for oily and organic solvent containing waste water treatment.