Adsorption of ammonium by different natural clay minerals: Characterization, kinetics and adsorption isotherms

A Alshameri, H He, J Zhu, Y Xi, R Zhu, L Ma, Q Tao - Applied Clay Science, 2018 - Elsevier
Applied Clay Science, 2018Elsevier
This research presented six natural clay minerals (NCM) evaluated for the effectiveness of
NH 4+ adsorption from aqueous solution. For the first time, the NH 4+ adsorption capacities
of kaolinite, halloysite, montmorillonite, vermiculite, palygorskite, and sepiolite were
examined and compared in the same study. All the NCM were fully characterized by XRD,
SEM/EDS, XRF, FTIR, CEC, zeta potential and nitrogen adsorption-desorption isotherms to
better understand the adsorption mechanism-property relationship. Adsorption kinetics …
Abstract
This research presented six natural clay minerals (NCM) evaluated for the effectiveness of NH4+ adsorption from aqueous solution. For the first time, the NH4+ adsorption capacities of kaolinite, halloysite, montmorillonite, vermiculite, palygorskite, and sepiolite were examined and compared in the same study. All the NCM were fully characterized by XRD, SEM/EDS, XRF,FTIR, CEC, zeta potential and nitrogen adsorption-desorption isotherms to better understand the adsorption mechanism-property relationship. Adsorption kinetics showed that the adsorption behavior followed the pseudo-second-order kinetic model. The adsorption isotherms fitted by the Langmuir model illustrated that among all the NCM studied, vermiculite (50.06 mg/g) and montmorillonite (40.84 mg/g) showed the highest ammonium adsorption capacities. Our results revealed that the cation exchange is the main mechanism for the NH4+ adsorption. Additionally, negatively charged surface, water absorption process and surface morphology of NCM might also contribute to the high adsorption capacity for the NH4+. The maximum adsorption capacities for all NCM were rapidly obtained within 30 min with a dosage of 0.3 g/25 mL at pH of 7. The results illustrated that the NCM have significant potential as economic, safe and effective adsorbent materials for the NH4+ adsorption from the aqueous solution.
Elsevier
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