In this study, the optimum ammonium removal by activation of synthetic zeolite in the aqueous phase was investigated by batch ion exchange adsorption assay, and its surface changes due to activation modification was elucidated accordingly. Among the adsorbents examined, modified synthetic zeolite A-4 was the most effective at ammonium removal. The best activation condition of zeolite A-4 was established by Na+ and 300 °C heat treatment at pH around 6 to 7. Besides, the removal efficiency was investigated under various reaction conditions of pH, adsorbent dosage, stirring speed, and initial ammonium concentration. Finally, the adsorptive capacity Qe of synthetic zeolite A-4 activated by Na+ and heat treatment was determined as 31.9 mg/g at 1,000 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 provided a better correspondence than the Freundlich isotherm. Finally, regeneration cycles for synthetic zeolite A-4 was determined for further industrial applications and efficient ammonium removal.
This work was supported by the Ministry of Trade, Industry and Energy (MOTIE, Korea) under KETEP Program No. 20162220100260, \u2018Development of Innovative Technology against Accidental Release of Toxic Gases in Industrial Sectors\u2019. This work was also supported by the Next-Generation Biogreen 21 Program (SSAC, No. PJ013128) funded by the Korean government RDA (Rural Development Administration). This work was partially supported by the National Research Foundation of Korea (NRF) grant, funded by the Korea government (MEST) (NFR-2018R1D1A1B07046920).
