Zeolitization Of Fly Ash And Their Applications In Treating Wastewater

This program makes use of silicon dioxide and alumina in fly ash, and then activates it by alkali hydrothermal reaction after acidification to make it a kind of absorbents to be used in disposal of wastewater such as printing. The purpose is to dispose wastewater with castoff and protect agricultural water resource.In this paper, the chemical and physical properties and mineral components of fly ash are mentioned. Present condition of fly ash comprehensive utilization is also discussed especially in field of disposal of wastewater. Alkali concentration, liquid-solid ratio, reaction time and bake temperature are analyzed in experiment of absorbent preparation. Color removal rate and COD removal efficiency are studied by changing the factors such as dosage, pH value, temperature and temporal time. Reprocess test of absorbent is also researched. The mechanisms of adsorption and zeolitization are initial studied. The main results are as follows:(1) The optimal conditions to prepare absorbent is acidification time, 24h; alkali concentration, 3mol/L; liquid-solid ratio, 10; crystallization temperature, 100℃; crystallization time, 8h; sintering temperature, 500℃; sintering time, 1h.(2) Dosage is maximal influence factor to color removal rate. Temperature is minimal influence factor. Color removal rate can reach over 90% after ten-minute adsorption.(3) Color removal rate of actual printing and dyeing wastewater can reach over 80% when the condition is pH value, 7; dosage, 10g/L; temporal time, 10min. Meanwhile, its COD removal efficiency can reach over 70%. COD removal efficiency of domestic sewage can reach over 90% when the condition is dosage, 8g/L; temporal time, 8min.(4) The absorbent that had been used can be reprocessed, and the reprocessed one has good performance in the adsorption also. Its first adsorptive ability is 85% of primal absorbent.