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An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid
Wang, L., C. Han, M. Nadagouda, AND D. Dionysiou. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid. JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, 313:283-290, (2016).
Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21±1 oC was up to 60 mgC•g−1. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, Raman spectroscopy, and high resolution transmission electron microscopy. The results showed the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for counter ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased remarkably after acid modification. Batch experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions due to strong electrostatic interactions between negative functional groups of HA and positive charges of ZnO-coated zeolite adsorbents.