Mesoporous silica production from Bergama Gold Mine waste and investigations of its production parameters

The aim of this study was the synthesis of MCM-41 from Bergama gold mine waste, which provided a high silicon source, and the investigation of the synthesis? parameters. The silicon contents of the gold mine waste were investigated with XRF analysis, which proved the waste contained silicon. The analysis indicated that the gold mine waste contained 77.7% silicon by weight and also has other components (Al2O3, K2O, CaO, TiO2, MnO, Fe2O3, MoO3 ve BaO.)For the extraction of silicon from gold mine waste, two different methods were investigated, ultrasonic and fusion. The solutions obtained with these methods were examined using ICP/OES analysis, reporting silicon contents of 5470 mg/L and 28030 mg/L respectively. Accordingly, the fusion method is optimal for the synthesis of MCM-41; therefore, this method was used for experimental synthesis of MCM-41.The reaction time, temperature, and pH adjustments are the parameters which have most influence on the synthesis? mechanism. For the purpose of examining these parameters, the synthesis was achieved at different reaction times (15 minutes, 30 minutes, 60 minutes, 90 minutes and 180 minutes), reaction temperatures (30 oC, 40 oC, 50 oC, 60 oC and 70 oC) and both alkaline pH adjustments (1-6 pH) and asidic pH adjustments (7-14 pH). According to the XRD and FT-IR analysis, the optimum conditions were discovered to be at 30 oC, 60 minutes and pH 11.After the discovery of the optimum conditions for the MCM-41 synthesis, from gold mine waste (MA), and for a comparison, a reference synthesis of MCM-41 (MSS), from a pure silicon source (TEOS), was done. The properties of MSS were examined by XRD, FT-IR, SEM and TG/DTG analysis. In addition, the properties of MA were examined by XRD, FT-IR, XPS, TEM, SEM and TG/DTG analysis. The effect of calcinations to MSS and MA were studied with XRD and FT-IR analysis and the investigated calcinations assisted the evaporation of surface moisture, surfactant and silanol groups.In addition the thermal analysis were done before calcination process and due to this analysis Kissenger-Akahire-Sunose (KAS) and Friedman (FR) kinetic methods were examined for MSS and MA structures. These two kinetic methods? results were proved to be nearly identical.