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The present research accounted for an accurate selection of representative samples from zeolitized deposits of different world geographical areas commonly mined and marketed by American and European mining companies. These geomaterials displayed high contents of clinoptilolite, phillipsite, and chabazite and were deeply characterized from mineralogical, chemical, and technological points of view. A preliminary quality control of the selected materials allowed us to determine the presence of undesired minerals and/or elements. A thermodynamic investigation of the surface exchange reactions between the selected zeolite-rich rocks and the surfactant agents (HDTMA-Br/Cl, hexadecyltrimethylammonium bromide/chloride, BC-Cl, benzalkonium-chloride, CP-Cl, cetylpiridinum-chloride) enabled us to verify the extent and the compactness of the formed micelle and to foresee their future behavior through interaction with molecules of anti-inflammatory drugs (drug delivery). The encouraging results pave the way towards good perspectives on the possible use of zeolite-rich rocks in the pharmaceutical sector through a preliminary basic protocol for the characterization and monitoring of the batches to be employed.

This work aimed to investigate the possible use of phillipsite (PHI) and chabazite (CHA), superficially modified with the cationic surfactant cetylpyridinium chloride (CP), for the controlled release of diclofenac sodium (DS) and compare them with the commercial clinoptilolite (CLI). Zeolites were characterized by confocal scanning laser microscopy (CLSM), powder X-ray diffraction and laser light scattering (LS). Furthermore, drug loading, powder flowability and in vitro drug release kinetics in simulated intestinal fluid (SIF), were investigated to assess the relationship between rock mineralogy and their pharmaceutical properties. Results showed that surfactant-modified natural zeolites (SMNZ)-CLI powder presents the best flow properties, followed by SMNZ-PHI and SMNZ-CHA. DS loading was very rapid (

The pozzolanic action played by five natural zeolite-rich materials (three clinoptilolite- and one each mordenite- and analcime-bearing rocks) coming from Turkey, has been examined, evaluating also the influence of various chemical–physical parameters, such as grain size of the zeolitic materials and nature of the cation present as extra-framework component of the structure. Pozzolan activity has been estimated by the official test of the European Standards and by thermogravimetry, finding a good accordance between the two procedures. Clinoptilolite-rich rocks gave the best results, but performance turned out to depend on the specific surface area and pre-enrichment in a potassium form. Experimental data analysis demonstrated that the pozzolanic reaction is kinetically controlled by the diffusion of reactants through a layer of dense reaction products. Experimental blended cements with the five zeolite-rich rocks were also prepared and the compressive strengths measured as a function of the curing time. The effectiveness of the pozzolanic action was monitored by XRD and FTIR analyses. An accurate microstructural study of the hardened pastes was also carried out and point analysis performed, pointing out that the zeolite-lime interaction is characterized by two stages: initially zeolite subtracts calcium from the environment by cation exchange, then it acts as a true pozzolan as soon as its structure breaks down.

This paper aims at testing the use of mixtures constituted by natural zeolitized products and SiC-bearing industrial wastes (sludge deriving from polishing of porcelain stoneware tiles, hereafter DPM) for the production of lightweight expanded aggregates as constituents of structural and/or thermo-insulating lightweight concretes. Two commercial products have been used as zeolite natural source: Cab70 (Yellow facies of Campanian Ignimbrite) and IZclino (Turkish clinoptilolite-rich epiclastite). Different amounts of a calcareous material (Pozzano limestones — hereafter CP) from the Sorrento peninsula (Naples — Italy) were also added to a Cab70–DPM mixture. All raw materials were characterized by means of mineralogical (XRPD) and chemical (XRF) analyses. All the products and mixtures were tested from a technological point of view by means of fusibility and firing tests in order to evaluate the expanding properties. It was evidenced that the expansion of the mixture was deeply depending on the occurrence of SiC in the industrial waste. The addition of CP (10 wt.%) to the mixtures accounts for an even increased expansion, though this is accompanied by a worsening of the mechanical features of the material. These results along with literature data allowed to select 3 mixtures (70% Cab70–30% DPM, 70% IZclino–30% DPM, 60% Cab70–30% DPM–10% CP) and each of them was used for the preparation of 5 l of lightweight aggregates afterward employed for the manufacture of lightweight concretes. It was remarked that natural zeolitized materials mixed with DPM (30 wt.%) can provide lightweight aggregates with densities ranging between 0.8 and 1.0 g/cm 3 suitable for the preparation of structural lightweight concretes. The addition to the mixture of CP (10 wt.%) produces less dense aggregates (0.6–0.7 g/cm 3 ) potentially useful for the manufacture of thermo insulating lightweight concretes.

In view of zeolite potentiality as a carrier for sustained drug release, a clinoptilolite-rich rock from California (CLI_CA) was superficially modified with cetylpyridinium chloride and loaded with diclofenac sodium (DS). The obtained surface modified natural zeolites (SMNZ) were characterized by confocal scanning laser microscopy (CLSM), powder X-ray diffraction (XRPD) and laser light scattering (LS). Their flowability properties, drug adsorption and in vitro release kinetics in simulated intestinal fluid (SIF) were also investigated. CLI_CA is a Na- and K-rich clinoptilolite with a cationic exchange ability that fits well with its zeolite content (clinoptilolite = 80 wt.%); the external cationic exchange capacity is independent of the cationic surfactant used. LS and CLSM analyses have shown a wide distribution of volume diameters of SMNZ particles that, along with their irregular shape, make them cohesive with scarce flow properties. CLSM observation has revealed the localization of different molecules in/on SMNZ by virtue of their chemical nature. In particular, cationic and polar probes prevalently localize in SMNZ bulk, whereas anionic probes preferentially arrange themselves on SMNZ surface and the loading of a nonpolar molecule in/on SMNZ is discouraged. The adsorption rate of DS onto SMNZ was shown by different kinetic models highlighting the fact that DS adsorption is a pseudo-second order reaction and that the diffusion through the boundary layer is the rate–controlling step of the process. DS release in an ionic medium, such as SIF, can be sustained for about 5 hours through a mechanism prevalently governed by anionic exchange with a rapid final phase.

Three Italian zeolitized volcanoclastic deposits with predominant phillipsite, chabazite or clinoptilolite were selected to investigate their attitude to form ceramized products of the Cs- and Sr-enriched forms and to evaluate the effectiveness of immobilization by means of leaching tests. The mineralogical evolution was carefully followed after thermal treatments at increasing temperatures (800 °C up to 1100 °C) which led to the crystallization of prevailing pollucite for Cs-exchanged phillipsite and chabazite and of a Sr-feldspar (about 35 wt.%) along with cristobalite and amorphous matter for all Sr-exchanged zeolites. Cs-enriched clinoptilolite at the same temperature was almost totally amorphous. Leaching tests confirm the substantial immobilization of the polluting cations in the ceramized materials with slight higher values only for the Cs-enriched clinoptilolite, mostly amorphous. Finally, calorimetric tests account for a hydrolysis process widely decreasing after thermal treatments at 1100 °C for phillipsite and chabazite, both Cs- and Sr-enriched, substantially similar for Sr-enriched clinoptilolite and definitely increased in the prevailing amorphous Cs-enriched clinoptilolite. © 2011 Elsevier B.V. All rights reserved.

The aim of this research is to assess the possible use of Italian zeolitic rocks for the production of lightweight aggregates. In particular, both the expansion at high temperature and the technological features of fired products were investigated. Fifteen zeolite-bearing volcanoclastites from Northern Sardinia and three zeolitized tuffs from Campania and Tuscany (Sorano and Campanian ignimbrites and Neapolitan Yellow Tuff) were taken into account. The firing expansion turned out to be mainly dependent on the chemical composition (especially SiO 2 and fluxing oxides such as Fe 2 O 3 , Na 2 O, K 2 O, MgO and CaO) and the water content (largely related to the zeolite amount) of the raw materials. Other relevant parameters were the temperature of maximum expansion (ranging between 1350 and 1500 °C, without additives) and soaking time (between 2 and 5 min). Some products are highly impervious to water (water absorption below 1%) and exhibit a considerable firing expansion (>100% in volume), a low bulk density (0.5–0.7 g·cm −3 ) and fair technical properties (loose weight and strength of particles). These encouraging results make some of the investigated tuffs interesting raw materials for the production of lightweight aggregates.

Two clinoptilolites from genetically different volcanoclastic formations have been studied. Both deposits are located in the Logudoro region (North-Western Sardinia, Italy) within epiclastic and pyroclastic formations related to calcalkaline volcanic activity. Chemical characterization performed by electron microprobe analysis on both samples showed a quite similar composition ([Si/(Si+Al)] = 0.81/0.82), with the exception of some extra-framework cations. In particular the epiclastic clinoptilolites turned out to be much higher in Mg content (0.72 vs. 0.26 a.f.u.) and considerably lower in K (1.10 vs. 2.37 a.f.u.) than the pyroclastic clinoptilolites. Previous investigations evidenced a different behaviour of the two clinoptilolite samples towards cation exchange processes and a substantial difference between the theoretical and experimental CEC. In this frame, Rietveld refinements based on synchrotron data allowed to define a different cationic population within the four exchangeable cation sites.