Experimental investigation on ammonia-nitrogen adsorption performance of ZSM-5 molecular sieve prepared from coal gangue and fly ash

Utilizing waste to treat waste not only resolves environmental issues but also enhances the resource value of waste. This study focused on the preparation of ZSM-5 molecular sieves from fly ash (FA) and coal gangue (CG) and their effectiveness in treating ammonia nitrogen in wastewater. The results indicated that with an FA to CG ratio of 7:3, an alkali fusion temperature of 750 degrees C, a crystallization temperature of 180 degrees C, and a crystallization time of 12 h, the crystallinity of the synthesized ZSM-5 molecular sieve exceeded 90 %. The optimal adsorption capacity was observed at an initial ammonia nitrogen concentration of 150 mg/L, with the addition of 150 mg of ZSM-5 molecular sieve and an adsorption time of 100 min. Under these conditions, the removal rate of ammonia nitrogen in simulated wastewater reached 88 %. Although the adsorption capacity for ammonia nitrogen in natural wastewater slightly decreased, the removal rate still exceeded 80 %. Furthermore, the results of the cycling test showed that after five cycles in simulated wastewater and natural wastewater, the removal rates reached 81 % and 73 %, respectively, indicating excellent stability.