Separation and Purification Technology 46 (2005) 155–160 Ammonium removal from aqueous solution by natural zeolite, Transcarpathian mordenite, kinetics, equilibrium and column tests Myroslav Sprynskyy a,b , Mariya Lebedynets a,c , Radoslaw Zbytniewski a , Jacek Namie´ snik d , Boguslaw Buszewski a,∗ a Department of Environmental Chemistry and Ecoanalytics, Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarina Str., 87-100 Toru´ n, Poland b Department of Oil and Gas Hydrogeology, Hydrogeochemistry and Hydrosphere Protection, Institute of Geology and Geochemistry of Combustible Minerals, Ukrainian National Academy of Sciences, 3a Naukova Str., 79053 L’viv, Ukraine c Department of Ecological and Engineering Geology and Hydrogeology, Ivan Franko L’viv National University, 4 Grushevsky Str., 79005 L’viv, Ukraine d Department of Analytical Chemistry, Chemical Faculty, Technical University of Gda´ nsk, 11/12 G. Narutowicza, 80-952 Gda ´ nsk, Poland Received 3 November 2004; received in revised form 3 May 2005; accepted 9 May 2005 Abstract The scope of this study was ammonium ions removal from synthetic aqueous solutions by raw and pretreated natural zeolite, Transcarpathian mordenite under static and dynamic conditions. The cation exchange capacity of the Transcarpathian mordenite regarding ammonium ions was evaluated as 1.64 meq/g at 1000 mg/l initial NH 4 –N concentration. The dynamic exchange capacity exceeded one estimated in equilibrium study at the same initial concentration that may be conditioned by the constant removal of ion exchange products. Ammonium uptake rate was controlled by particle diffusion with diffusion coefficients determined in the range of 0.7–3.6 × 10 -12 m 2 /s. Efficiency of ammonium sorption may be improved by slowing down of initial solution rate in the column test and non-significantly by NaCl and HCl pretreatment of the mordenite. Ammonium sorption by the mordenite increased from the coarser to the finer fraction but this dependence became weaker to low flow rates. It was established that hydrogen ions displaced exchangeable cations on the mordenite in distilled water and hydrochloric acid with destroy of the zeolite framework structure in the last case. NH 4 + -ions removal from aqueous solutions occurs mainly by ion exchange with Na + - and Ca 2+ -ions at the practically equal parts of them because of the weakest affinity of the mordenite to these cations. © 2005 Elsevier B.V. All rights reserved. Keywords: Mordenite; Ion exchange; Ammonium removal; Kinetic and column tests 1. Introduction Ammonium ions being often the primary form of the widespread nitrogen pollution of hydrosphere compromise mostly the surface waters causing increases of oxygen demand and eutrophication in rivers and lakes. Natural processes of water purification from nitrate(V) ions are often impossible in subsurface aquifers due to recharge sources, filtration velocities and water volumes. Hence, prevention of ∗ Corresponding author. Tel.: +48 56 611 48 37; fax: +48 56 611 48 37. E-mail address: bbusz@chem.uni.torun.pl (B. Buszewski). nitrogen pollution with ammonium removal from wastewater as a necessary stage is of a great importance. Among various methods available for ammonium removal from waters and wastes ion exchange looks like the most attractive one when the effective, low cost materials are used as exchangers. Zeolites being crystalline hydrated aluminosilicates of framework structure contain pores occupied by water and alkali and alkaline earth cations and are the well-known ion exchangers all over the world [1,2]. Despite the great interest in ion exchange with zeolites, few data exist on the ammonium ions exchange with mordenite, in terms of diffu- sion coefficient especially [1,3–6]. Ion exchange, as a rule, 1383-5866/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2005.05.004