Synthesis and characterization of Na-P1 (GIS) zeolite using a kaolinitic rock

Abstract

This work focuses on the hydrothermal synthesis of Na-P1 zeolite by using a kaolinite rock coming from Romana (Sassari, Italy). The kaolin is calcined at a temperature of 650 °C and then mixed with calculated quantities of NaOH. The synthesis runs are carried out at ambient pressure and at variable temperatures of 65 and 100 °C. For the first time compared to the past, the Na-P1 zeolite is synthesized without the use of additives and through a protocol that reduces both temperatures and synthesis times. The synthesis products are analysed by X-ray diffraction, high temperature X-ray diffraction, infrared spectroscopy, scanning electron microscopy and inductively coupled plasma optical emission spectrometry. The cell parameters are calculated using the Rietveld method. Density and specific surface area are also calculated. The absence of amorphous phases and impurities in synthetic powders is verified through quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. The results make the experimental protocol very promising for an industrial transfer.

Synthesis and characterization of analcime (ANA) zeolite using a kaolinitic rock

“…For the chemical composition of kaolin and its mineralogical, morphological and spectroscopic characterization, see Novembre et al 47 . The kaolin was triturated, and the sandy fraction was separated by retention in a sieve; then the fraction below 90 μm was collected, suspended in distilled water, sonicated, and centrifuged for separation of the silt fraction and collection of the clay fraction 49 . Preliminary calcination of kaolin was carried out in open porcelain crucibles heated in a Gefran Model 1200 furnace (Gefran Spa, Brescia, Italy) to the calcination temperature (650 °C) at a pressure of 1 atm.…”

“…Identification of analcime and relative peak assignment was performed with reference to the following JCPDS code: 00-019-1180. Both the crystalline and amorphous phases in the synthesis powders were estimated using quantitative phase analysis (QPA) applying the combined Rietveld and reference intensity ratio (RIR) methods; corundum NIST 676a was added to each sample, amounting to 10% (according to the strategy proposed by Novembre et al 47 , 49 and the powder mixtures were homogenized by hand-grinding in an agate mortar. Data for the QPA refinement were collected in the angular range 5°–110° 2theta with steps of 0.02° and 10 s step −1 , a divergence slit of 0.5° and a receiving slit of 0.1 mm.…”

“…As regards the use of clays, kaolin is the material already tested in the synthesis of analcime. Among clay minerals, in fact, kaolinite is the most used phyllosilicate in the zeolitic synthesis because of its particularly large supply and availability and the well-known activity of thermally treated kaolin clays (metakaolin) when treated with alkali-based reagents 43 – 49 . Rios et al 50 treated kaolinite with NaOH and obtained co-crystallization of analcime and other zeolites; Hegazy et al 22 synthesized analcime by hydrothermal reaction of kaolin and commercial sodium silicate solution at 200 °C for 24 h under autogenous pressure; Atta et al 40 synthesized analcime from kaolin after 72 h aging and 24 h reaction time at temperature of 180 °C; Jamil et al 41 mixed Kaolinite, Ludox 40 and NaOH and get analcime after 30 min at 160 °C in a microwave system; Moraes et al 51 treated calcined kaolin and diatomaceous earth with NaOH at 210 °C for 24 h and obtained analcime with minor amounts or residual quartz; Kwaky-Awuah et al 52 synthesized powders of LTA, analcime and X zeolite starting from Kaolin and bauxite; Ramirez-Zamora et al 33 synthesized polimineralic powders of analcime by fly ash and kaolinite; Abdul-Moneim et al 53 treated kaolin with NaOH at 170 °C for 36 h and obtained co-crystallizations of analcime, cancrinite and sodalite.…”

“…a kaolinitic rock coming from Romana (Italy). This kaolin has already been successfully used in the past in the synthesis of useful minerals 47 – 49 . Romana kaolin has the advantage of being characterized by an excess of silica compared to common commercial kaolin, being its mineralogical composition made of kaolinite plus minor amounts of quartz and opal-crystobalite 47 .…”

Synthesis and Characterization of Analcime (ANA) Zeolite using a Kaolinitic Rock

“…The scope of the present work is to synthesize monomineralic powders of Analcime by testing a natural rock, i. e. a kaolinitic rock coming from Romana (Italy). This kaolin has already been successfully used in the past in the synthesis of useful minerals [28][29][30]. Roman kaolin has the advantage of being characterized by an excess of silica compared to common kaolins, being its mineralogical composizion made of kaolinite plus minor amounts of quartz and opal-crystobalite [28].…”