Adsorption characteristics and mechanisms of high-levels of ammonium from swine wastewater using natural and MgO modified zeolites

Abstract

A B S T R A C TThis paper focuses on the effectiveness of removing ammonium by both natural and MgO modified zeolites and the theoretical aspects of adsorption including mechanisms. Results have demonstrated that the zeolite synthesized by integrated calcination with MgO at 400˚C performances a good ammonium adsorption capacity as high as 24.9 mg g −1 , an increase by 97.6 and 68.2% compared to that of natural zeolite itself and natural zeolite that heated in 400˚C for 4 h (12.6 and 14.8 mg g −1 , respectively), when its dose was adjusted at 27 g L −1 with solution pH of 8.3 and agitation speed of 280 r min −1 at 25˚C. Negative Gibbs free energy change indicated the spontaneous nature of the adsorption. In addition, both ionexchange and molecular adsorption being the main mechanisms, in which ion-exchange dominated the ammonium adsorption process near neutral pH, and the molecular adsorption was of secondary importance, and contributed less to the total ammonium removal according to the experimental results under neutral pH conditions.

Microwave-assisted synthesis of coal fly ash-based zeolites for removal of ammonium from urine

“…Nonetheless, the concentration of K + ions in solution was reduced after adsorption indicating possible re-adsorption by the adsorbents due to its strong affinity to zeolites. 38 On the other hand, coal fly ash demonstrated minimal cation exchange due to its low cation exchange capacity and therefore displayed the lowest ammonium ion removal ( Table 6 ). Ion-exchange was not the only controlling mechanism during the adsorption process.…”

Removal of Ammonium from Swine Wastewater Using Synthesized Zeolite from Fly Ash

“…The removal function is based on the adsorption of zeolites for nonionic ammonia and on the ion exchange of zeolite with ionic ammonia, because zeolite can provide sorption sites with exchangeable cations for NH 4 + and porosity for free ammonia [43]. The form of ammonia existing in solutions is determined by pH, temperature, and others [44]. The free ammonia is prone to be adsorbed in the channel of zeolite in the form of physical adsorption.…”

Synthesis of Zeolite-Supported Magnesia-magnetite Nanoparticles and Its Efficient Application in Ultrasound-Assisted Adsorption of Dairy Wastewater: Optimization and Modeling of Process by RSM and ANN

“…3 Zeolite-based magnesia compounds are among the most popular adsorbents that, by 52 a synergistic effect, could overcome most problems triggered by the removal of 53 organic and inorganic pollutants in liquid or gaseous phases [13][14][15].…”