Efficiency, mechanism and application prospect of ammonium adsorption and desorption over a sodium-acetate-modified synthetic zeolite.

Adsorption is an effective approach for remediating ammonium pollution, and zeolite has exceptional efficacy for the adsorption of ammonium. The investigation of ammonium adsorption using coal-fly-ash-based zeolite has gained remarkable attention in contemporary research. In this work, a sodium-acetate-modified synthetic zeolite (MSZ) was used to absorb ammonium in simulated wastewater. The MSZ had an adsorption capacity for ammonium of 27.46 mg g, and the adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetics model. The adsorption and desorption of ammonium were controlled by ion exchange, pore diffusion, and electrostatic attraction processes. Ion exchange was responsible for 77.90% of the adsorption process and 80.16% of the desorption process. The MSZ was capable of continuously removing large amounts of ammonium from wastewater through fixed bed adsorption. After 5 regeneration cycles, MSZ still maintained 75% adsorption characteristics for ammonium. Using MSZ adsorbed with ammonium as a soil amendment increased the germination rate of mung beans by 10%. Furthermore, it also increased the stem length, root length, and fresh weight by 20-30%. These findings suggest that MSZ provides a promising application prospect to mitigate ammonium pollution and recycle ammonium resources.