New Materials Synthesized by Sulfuric Acid Attack Over Power Plant Fly Ash

Abstract

In the current work, the preparation of a complex wastewater coagulant based on polymeric sulfates of aluminum/iron from fly ash is presented. The performance of the coagulation�flocculation process is mostly influenced by the coagulant type, which enhances the aggregation of particles and leads to formation of fast-settling flocs by charge neutralization or chain-bridging mechanisms. Within the preparation process, the reaction temperature was controlled at 80�C and 90�C for 4 h, the synthesized materials being characterized through different techniques (SEM, EDAX, FTIR, and XRD) and further used as coagulants for real wastewater treatment. As a novelty of this study, it can be mentioned that there were analyzed the possibilities of capitalization of Romanian fly ash collected from Iasi area and its transformation into complex based on aluminum - iron sulfates. Fly ash containing different concentrations of Fe2O3 and Al2O3 was successfully used in producing complex coagulants by reacting with 10% technical sulfuric acid solution. The produced complex coagulants contain both polymeric ferric sulfate (PFS) and polymeric aluminum sulfate (PAS) (demonstrated by complex characterization) and proved to be effective in wastewater treatment. These sustainable materials exhibited a good performance in coagulation�flocculation process (e.g. it was obtained a TSS removal efficiency of 84% at the coagulant dosage of 60 mg/L).