Preparation of fly ash-based aerogel and investigating their adsorption capacity of organic molecules

Millions of tons of fly ash are released every year as a by-product in thermal power plants. These fly ashes spread out with the air and water and threaten the entire ecosystem, especially living things, due to the harmful components it contains. However, it contains high levels of silica as well as harmful components. By making use of this feature, the fly ash is recycled, and the silica component is extracted and made usable, while the carbon footprint is significantly reduced. This extracted silica component replaces expensive precursors used in aerogel production. Silica aerogel material has an exceptionally high surface area, low density, low thermal conductivity, etc. Thanks to its properties, it is used in space exploration, microelectronic sonics, acoustics, laser experiments, optics, medicine and water treatment applications. In this thesis, it is aimed to remove textile dyes in wastewater by utilizing the adsorption property of aerogel material. Anionic dyes such as methyl orange (MO) and xylene orange (XO) are widely used in the textile industry and are chemicals that threaten human life (toxic, carcinogenic and allergenic) when mixed with drinking water. For all these reasons, in this study, it is aimed to remove MO and XO dyes mixed with water from water in a short time (less than 30 minutes) with an efficiency of more than 90%. For this purpose, a precursor for the aerogel material was formed by extracting the silica component from fly ash, which is an inexpensive source. From this precursor, an aerogel with a surface area of 810 m2 g-1 was successfully produced by the ambient pressure drying method. By coating the protonable amine groups on the aerogel material with the silanation (tri amino propyl tri ethoxy silane, APTES) method, the adhesion of anionic dyes such as MO and XO to the aerogel adsorbent by electrostatic interaction was increased. In the experiments, it was determined that APTES coated aerogel adsorbent, which was used in very low amounts, removed both MO and XO dyes from water 100%. In addition to all these, to measure the reusability of the adsorbent, 10 cycles of the adsorption-desorption experiment were performed and tested. In the 10th cycle, 83% of the MO dye was removed from the water, while 88% of the XO dye was removed. Another advantage of this study is that the dye removal process took less than 5 minutes.