Hydrothermal modification of natural zeolites to improve uptake of ammonium ions

Journal of Chemical Technology & Biotechnology (Impact Factor: 2.5). 03/2005; 80(4):376 - 380. DOI: 10.1002/jctb.1224

ABSTRACT The modification of natural zeolites was carried out under hydrothermal conditions to improve the effectiveness of the uptake of ammonium ions. Natural zeolites originating in Japan, such as mordenite and clinoptilolite with quartz, feldspar and a trace of layered silicate, were treated with 0.1, 0.3, 1.0 and 3.0 M NaOH solutions at temperatures from 25 to 150 °C under autogenous pressure for 7 days. After the hydrothermal treatment, the transformation of the zeolites to phillipsite, hydroxyl-sodalite and analcime was observed, depending on the temperature and NaOH concentration. The amounts of ammonium ions taken up into the hydrothermally-treated zeolites were compared with those of the starting materials. The treated products, containing mainly phillipsite, took up twice the amount of ammonium ions as the starting materials. The maximum uptake of ammonium ions was 1.92 mmol g−1. The number of ammonium ions taken up into phillipsite was equal to the number of Na+ ions released from phillipsite. These results indicate that the uptake of ammonium ions proceeds by an ion-exchange mechanism with Na+ ions. Copyright © 2005 Society of Chemical Industry

  • [Show abstract] [Hide abstract]
    ABSTRACT: The Chinese natural zeolite, in which clinoptilolite coexists with quartz was treated hydrothermally with NaOH solutions, either with or without fusion with NaOH powder as pretreatment. Zeolite Na-P, Na-Y and analcime were identified as the reacted products, depending on the reaction conditions such as NaOH concentration, reaction time and hydrothermal temperature. The products were identified by X-ray diffraction, and characterized by Fourier transform IR and ICP. With hydrothermal treatment after fusion of natural zeolite with NaOH, high purity of zeolite Na-Y and Na-P can be selectively formed, their cation exchange capacity (CEC) are 275 and 355 meq/100g respectively, which are greatly higher than that of the natural zeolite (97 meq/100g). Furthermore, the ammonium removal by the synthetic zeolite Na-P in aqueous solution was also studied. The equilibrium isotherms have been got and the influence of other cations present in water upon the ammonia uptake suggested an order of preference Ca(2+)>K(+)>Mg(2+).
    Journal of hazardous materials 01/2009; 166(2-3):1014-9. · 4.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Natural zeolites are abundant and low cost resources, which are crystalline hydrated aluminosilicates with a framework structure containing pores occupied by water, alkali and alkaline earth cations. Due to their high cation-exchange ability as well as to the molecular sieve properties, natural zeolites have been widely used as adsorbents in separation and purification processes in the past decades. In this paper, we review the recent development of natural zeolites as adsorbents in water and wastewater treatment. The properties and modification of natural zeolite are discussed. Various natural zeolites around the world have shown varying ion-exchange capacity for cations such as ammonium and heavy metal ions. Some zeolites also show adsorption of anions and organics from aqueous solution. Modification of natural zeolites can be done in several methods such as acid treatment, ion exchange, and surfactant functionalisation, making the modified zeolites achieving higher adsorption capacity for organics and anions.
    Chemical Engineering Journal. 01/2010;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The present study concerns the synthesis of zeolites from Neogene sedimentary and pyroclastic rocks exposed around the Sochagota Lake, Paipa (Boyacá). Two synthesis methods were used: conventional hydrothermal treatment and alkaline fusion followed by hydrothermal reaction. Both raw materials and synthesised zeolytic products were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Several zeolytic phases were synthesised, including faujasite (FAU), phillip-site (PHI) and sodalite (SOD). The results showed that the alkaline fusion approach was more efficient regarding hydrothermal conversion of the raw materials than conventional hydrothermal treatment, taking into account that zeolytic products having a higher degree of crystallinity and few impurities were obtained in this way. This study was aimed at applying experimental mineralogy to a laboratory simulation of the geological conditions in which zeolites can occur as the basis for defining criteria for exploring natural zeolites in Colombia, with prospects for the profitable exploitation of these mineral resources in different parts of Colombia.
    Earth Sciences Research Journal 12/2011; 15(2):89-100. · 0.13 Impact Factor

Full-text (2 Sources)

Available from
Jun 3, 2014