Zeolitisation of perlite fines: Mineralogical characteristics of the end products and mobilization of chemical elements

Christidis, GE; Paspaliaris, I; Kontopoulos, A

dc.contributor.author	Christidis, GE	en
dc.contributor.author	Paspaliaris, I	en
dc.contributor.author	Kontopoulos, A	en
dc.date.accessioned	2014-03-01T01:15:23Z
dc.date.available	2014-03-01T01:15:23Z
dc.date.issued	1999	en
dc.identifier.issn	0169-1317	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13471
dc.subject	Alkalinity	en
dc.subject	Hydroxysodalite	en
dc.subject	Perlitic glass	en
dc.subject	Zeolite-P(c)	en
dc.subject	Zeolite-V	en
dc.subject	Zeolitisation	en
dc.subject.classification	Mineralogy	en
dc.subject.other	perlite	en
dc.subject.other	zeolite	en
dc.subject.other	Alkalinity	en
dc.subject.other	Alumina	en
dc.subject.other	Caustic soda	en
dc.subject.other	Glass	en
dc.subject.other	High temperature effects	en
dc.subject.other	Potassium	en
dc.subject.other	Silica	en
dc.subject.other	Silicon	en
dc.subject.other	Sodium	en
dc.subject.other	Hydroxysodalite	en
dc.subject.other	Perlitic glass	en
dc.subject.other	Zeolitization	en
dc.subject.other	Zeolites	en
dc.title	Zeolitisation of perlite fines: Mineralogical characteristics of the end products and mobilization of chemical elements	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0169-1317(99)00007-1	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0169-1317(99)00007-1	en
heal.language	English	en
heal.publicationDate	1999	en
heal.abstract	This study examines the synthetic zeolites produced from perlite waste. Zeolitisation was carried out in autoclaves with NaOH solutions at 100 degrees-140 degrees C. The volcanic glass was converted to zeolite-P-c, zeolite-V and hydroxysodalite. The rate of conversion of the glass and the transformation of zeolites depended on temperature, time and NaOH concentration. The principal chemical changes observed between the initial glass and the end product involved the removal of Si and K and the uptake of Na. The amount of Si and K released increased with increasing alkalinity, reaching a steady state in the whole temperature range. The amount of Si at the steady state decreased with increasing temperature, while that of K followed an opposite trend. Therefore, the SiO2:Al2O3 ratio of the solid phase at steady state increased with increasing temperature. The amount of Na taken up increased with increasing alkalinity, increasing the Na2O:Al2O3 ratio and decreasing the SiO2:Na2O ratio of the solid phase, as reaction progresses. The crystallinity of zeolite-P-c increased with the amount of Na2O present in solution up to a maximum value, then decreased rapidly. The zeolite-P-c initially formed had a high SiO2:Al2O3 ratio, which then decreased gradually until zeolite-V was formed. Both zeolites were replaced by hydroxysodalite at higher alkalinity. Zeolite-V was metastable and converted to zeolite-P-c after prolonged exposure to the atmosphere. The average cation exchange capacity (CEC) of the zeolite products is 3.0 meq/g and equilibrium was attained very fast, suggesting that the products can be efficiently used for removal of ammonia from agricultural wastewater. At the described experimental conditions, hydroxysodalite was the stable Na-rich, Si-poor and zeolite-P, was the stable Si-richer phase. (C) 1999 Elsevier Science B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	Applied Clay Science	en
dc.identifier.doi	10.1016/S0169-1317(99)00007-1	en
dc.identifier.isi	ISI:000082847600001	en
dc.identifier.volume	15	en
dc.identifier.issue	3-4	en
dc.identifier.spage	305	en
dc.identifier.epage	324	en