期刊
WATER RESEARCH
卷 158, 期 -, 页码 246-256出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.watres.2019.03.045
关键词
Adsorption; Ligand-exchange; Mechanism; Phosphate; Reusability; Zeolite
资金
- Korea Institute of Civil engineering and building Technology (KICT), Rep. of Korea [20190151-001]
In this study, Fe-Zeolite-A as a phosphate adsorbent was synthesized by incorporating iron into the framework of Zeolite-A using ammonium iron citrate as the Fe(3+)source. The adsorption (in acidic condition) and desorption of phosphate (in alkaline condition) from an aqueous solution was repetitively performed for 18 times in batch test using Fe-Zeolite-A. The rate of adsorption and desorption of PO43- was much faster (consistently) than any of the reported study so far. The crystalline phase of pristine zeolite changed to amorphous after one adsorption phase and ultimately transformed into a highly amorphous phase after 18 adsorption/desorption cycles. It was due to the formation of more active sites on the surface of the zeolite by a release of atoms, breaking of bonds and deposition of metal and phosphate compounds on the surface (by rigorous acid/base treatment). Increase in active sites enhanced the sorption efficiency of Fe-Zeolite-A. With the help of microscopic and spectroscopic techniques, it was found that Fe3+, Al(3+)and Na+ metal ions of the Fe-Zeolite-A were involved in the adsorption/desorption of PO43-. Fe3+ ion exhibited ligand exchange mechanism by exchanging -OH ions with PO43-. Al(3+)and Na+ exhibited interactions like precipitation, hydrogen bonding, and diffusion respectively to adsorb PO43-. Fe3+ metal ion dominated over other metal ions by ligand exchange principle, making the sorption process a highly reversible one. The adsorbent showed quantitative adsorption/desorption capacity even after continuous 18 cycles indicating a higher level of reusability. (C) 2019 Published by Elsevier Ltd.
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