The effect of particle sizes on ammonium adsorption kinetics and desorption by natural zeolites

Authors : Veli UYGUR, Canan ŞANLI ÇELİK, Enise SUKUSU

Pages : 371-377

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Publication Date : 2019-12-23

Article Type : Research Paper

Abstract :Reducing the particle size of the adsorbents is an efficient way of manipulating the adsorption/desorption characteristics of the adsorbate. Therefore, we tested the effect of micronisation of two natural clinoptilolite specimens on the ammonium insert ignore into journalissuearticles values(NH4+); adsorption/desorption.  One g of adsorbent equilibrated with 20 mL solution containing 0-600 mg NH4+ L-1 at constant ionic strength. The adsorbate was extracted by molar KCl solution. Sorption kinetic was studied at 50, 300 and 600 mg L-1 concentrations for 5, 10, 20, 30 min; 1, 2, 4, 8, 16, and 24 h. The sorption data well confirmed both Freundlich and Langmuir sorption models. The Langmuir adsorption capacities insert ignore into journalissuearticles values(16667 mg kg-1); of both zeolites were similar but the sorption maximum of Gordes zeolite with 250-500 µm was smaller insert ignore into journalissuearticles values(14286 mg kg-1);. The particle size dependency was apparent for Gordes zeolite. The desorption ratio was dependent on initial NH4+ concentration, particle size, and zeolite type. In general, there was an increase in desorption ratio up to 300-400 mg L-1 initial ammonium concentrations. Results of the kinetic study indicated that the adsorption data better fitted the pseudo second-order kinetic model than the Elovich model. Zeolite having well-structured porous nature can be used in larger particle size to scavenge NH4+ from the polluted water sources, but initial sorption rate can be improved by particle size reduction. The sorption data indicated that the zeolites may be used for NH4+ removal from the polluted water sources or improving the sorption capacity of coarse soils to alleviate ammonium leaching problem.
Keywords : Natural clinoptilolite zeolite, ammonia, adsorption, desorption, particle size