Characteristics of ammonium adsorption by natural zeolite in solution

Selecting the natural clinoptilolite of Jinyun county, Zhejiang province, China, as experimental material, the kinetics of NH4+ adsorption by the natural zeolite was investigated. The diameter of the zeolite is 2~3.2 mm.. The result of the experiment shows that the process of ammonium adsorption by the natural zeolite is fitted to Langmuir adsorption isotherm and the first-order kinetics. The maximum of NH4+-N adsorption by the zeolite is 1.624 mol·kg-1 (zeolite) and the constant of reaction rate is 0.188 2 h-1. Through determining the amount of various cations in the solution, including of Ca2+, Na+, K+, Mg2+ and NH4+, Ca2+ and Na+ in zeolite crystal were considered as dominating participant in the process of ion exchange. Exchange amount of Ca2+, Na+ with NH4+ in solution oc- cupied about 96% of the total ion exchange amount. The ion in zeolite crystal distributing again in the solution results in the unequal exchange in the early exchange phase.