Improvement method for usage of fly ashes from different areas at adsorption of heavy metal ions

Fly ash is a significant waste that is released of thermal power plants and defined as very fine particles that are drifted uptaken by the flue gases due to the burning of coal. The amount of fly ash emerging in the world is approximately 600 million tons per year. Less than %25 of the total produced fly ash is utilized in the world. In recent years, Turkey has made inevitable of the expansion of the thermal power plants due to the increasing energy demand. In our country, approximately 13 million tons of fly ash per year are obtained at thermal power plants. It is expected that this amount will increase in the next years, depending on energy consumption. In our country, it is expected that 50 million tons of waste ash per year will be produced until 2020. It is already well known that the released waste from the thermal power plants causes significant problems. Assesment of this waste has been proven very beneficial in environmental, technical and economical terms, especially the production of concrete and cement in the construction sector. However, the amount of fly ash produced is very large, implementation of additional utilization areas are extremely important.The aim of this study is to investigate the possibility of using the pellets which consist the fly ashes taken from different regions of Turkey and binders (bentonite, ulexite and solution of molass) such as low-cost adsorbents for adsorption of heavy metals ions in waste water. First of all, fly ashes taken from different regions of Turkey were characterized by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier Transform İnfrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM) to view the morphology of raw materials, and Brauner-Emmett-Teller analysis (BET) for surface area analysis, sieve analysis, moisture (%), CaO (%) and Loss of Ignition (LOI) (%) of fly ashes. Then, the fly ashes and binders which are bentonite (0 and 1% in terms of fly ash, w/w), ulexite (0 and 1% in terms of fly ash, w/w) and molass (0-0.75 mL) were pelletized. The pellets were used in adsorption experiments and samples from waste water were taken during the experiments in range of 30-150 minutes were analyzed.The effects of process parameters like species of fly ash, amount of bentonite, amount of ulexite, amount of molass, time, type of pellet (spherical, cylindrical), species of high metal, pH and concentration on adsorption yield were investigated. It was seen that the experiments were not carried out successfully when the spherical pellets were used at adsorption of zinc and lead. When the cylindrical pellets were used, optimum points for Zn adsorption were Orhaneli fly ash (10 gr), bentonite (0%, in terms of fly ash, w/w) ve molass (0.25 ml) for the pellets are prepared by Orhaneli fly ash and Çatalağzı fly ash (10 gr), bentonite (1%, in terms of fly ash, w/w), molass (0.50 ml) for the pellets are prepared by Çatalağzı fly ash. Optimum points for Pb adsorption were Orhaneli fly ash (10 gr), bentonite (1%, in terms of fly ash, w/w) ve molass (0.50 ml) for the pellets are prepared by Orhaneli fly ash and Çatalağzı fly ash (10 gr), bentonite (1%, in terms of fly ash, w/w), molass (0.25 ml) for the pellets are prepared by Çatalağzı fly ash. In conclusion, it was seen that fly ashes which are the waste of thermal power plants, were pelletized with molass which is the waste of sugar industry and other binders by different methods and were used for adsorption of high metals from wastewater, so the wastes can be evaluated.