In this study, the ammonium removal efficiency of zeolite and activated carbons in the aqueous phase was investigated by batch adsorption assay. Among the adsorbents examined, synthetic zeolite A-4 was the most effective at ammonium removal in aqueous solution. The removal efficiency was measured under various reaction conditions of pH, adsorbent dosage, stirring speed, and initial ammonia concentration. The optimum pH was established to be between 6 and 7. The highest removal efficiency of 53% was achieved at a speed of 50 rpm. The higher the amount of adsorbent used, the higher the removal efficiency achieved, up to 89%. Finally, the adsorptive capacity of synthetic zeolite A-4 was determined as 26.6 mg/g at 1000 mg-N/L of ammonium, whereas that of natural zeolite was measured as 16.0 mg/g. The obtained adsorption data was fitted to both Langmuir and Freundlich isotherm models, and the Langmuir isotherm model (= 0.9900) provided a better correspondence than the Freundlich isotherm (= 0.9538). A value of 1/n between 0.1 and 1 was shown to be advantageous for the adsorption removal processes.
