Synthesis of Silica Xerogel from Bottom Ash of Reppi Waste to Energy as A Methylene Blue Adsorbent on Textile Wastewater

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Addis Ababa University


Dyes are water soluble complex organic compounds, it present in the textile dyeing process and they are nonbiodegradable waste in the textile wastewater. In Ethiopia, most textile factories are located nearby water bodies and they discharge their color effluent to canals, rivers, lakes, and streams without treatment. Those Effluents can harm all forms of living things. Among those dyes discharging MB dye without treatment can affect human life and aquatic life. The aims of this research were to synthesis silica xerogel from bottom ash by the sol-gel process to treat dyehouse waste. In this study the first stage was the leaching treatment to reduce heavy metal elements and to increase silica extraction, the second step was extraction process was employed to synthesize sodium silicate at different parameters such as extraction time (1, 2, and 3h), NaOH concentration (1, 2 and3M) and solid to liquid (wt: vol) ratio (1:1, 1:2 and1:3) with constant temperature 750c. Since the sol-gel process for all extracted sodium silicate were done at the same parameter such at room temperature, hydrosol pH 3, the addition of water 40mL slow constant stirring, 18h aging time, drying at 1050c for 24 hr and final silica gel pH7. The High percent of purity (84.1321%) of silica gel was obtained with the ratio 1:1.5, 2:5hr, and 2M of NaOH concentration with 0.901 desirability chosen as optimal sodium silicate extraction parameter. The physical and chemical characteristics of the mesoporous silica materials were analyzed using BET, FTIR and also their purity, moisture content, and bulk density was characterized. The results indicated that the BET surface area and pore diameter of the synthesized silica materials were 253.1 m2/g and 18.38Å; respectively. The FTIR spectra confirmed the existence of a surface hydroxyl group and the occurrence of symmetric Si–O stretching. The results indicate that purity, moisture content, and bulk density were 84.13, 5.26%, and 0.73gm/cm3 respectively. Under the experimental conditions at 30.85 min, 0.1g silica gel dosage for 13.94mg/L dye concentrations were found for maximum dye removal efficiency (86.101%) with0.99desirability. The optimal condition was checked on textile dye house water, which dye concentration was 14.81mg/L, the result becomes 84.62% dye removal efficiency. Consequently, the experimental results indicated that the bottom ash has the potential to be used as silica gel for dye removal.



silica gel, Methylen blue, bottom ash, removal efficeincy