Semi-quantitative analysis study of the impact of microwave treatment on fly ash

Abstract

Pre-processing provides an effective way for fly ash's high value-added utilization. However, the shortcomings of pre-processing methods such as grinding and flotation are apparent, with many disadvantages that make it more challenging to use efficiently. Microwave heating helps the SiO2-Al2O3 bond break, not only can make the structural change of the material can also promote the chemical reaction process. In the article, XRD, SEM, FT-TR, ammonia nitrogen adsorption, and other methods were used to analyze the changes in the properties of fly ash before and after microwave pre-treatment, the change of adsorption performance of fly ash before and after microwave treatment was analyzed. The study found that under microwave conditions of 600W and 15min, the adsorption rate of ammonia nitrogen by fly ash reached the maximum of 29.67%. The intensity of mullite and amorphous diffraction peaks decreased after 20 minutes at 600W. The Si-O-(Si, Al) and Si-O-(Si) bonds showed significant changes at 15 and 20 minutes under 600W conditions. Based on the results, microwave conditions were selected at 600W for different periods, and semi-quantitative analysis was carried out by XRD-Rietveld, infrared peak fitting, and nuclear magnetic resonance. The XRD-Rietveld analysis showed that the amorphous phase content reached 46.18% at 15 minutes. In the infrared peak fitting, the fitting area at 1300-900cm-1 and 600-400cm-1 peaks reaches 56.92% at 25 minutes and 17.5% at 15 minutes, respectively. The silicon-oxygen network's degree of connection and polymerization is reduced after 15 minutes of microwave treatment for the nuclear magnetic resonance analysis.