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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.

Main purpose of the research was to define an operative protocol, applicable at industrial scale, optimizing the functionalization of natural zeolites with surfactants, especially in pharmaceutical and environmental sphere. Three zeolite-rich samples from Italy (PHI_SAV), Slovakia (CLI_SK) and California (CLI_CA) were used for preparation of SMNZ. Two different protocols allowed to carry out surfactant adsorption equilibrium runs and surfactant sorption kinetics by varying different parameters: mixing speed (4000, 6000, and 8000 rpm); contact time (15 ÷ 90 min) and initial surfactant concentration (from 25% to 200% of the external cation exchange capacity - ECEC) at a constant solid/liquid ratio (1 g/50 mL). Zeolite-rich materials were treated with solutions of cetylpiridinium chloride (CP-Cl). The functionalization of SMNZ was obtained by using a high-speed disperser. The amount of absorbed surfactant onto two carriers (CLI_SK and PHI_SAV) was evaluated through kinetic experiments under the following conditions: the initial CP-Cl concentration of 150% of the ECEC and a disperser speed of 8000 rpm. Results showed that after 15 min, equilibrium was attained with the adsorbed amount of about 0.14 meq/g of CP-Cl (equivalent to the ECEC of the investigated zeolitic support), confirming formation of monolayer (emi-micelle). The functionalization (micelle formation) of two samples occurred after 70 min of solid/liquid interaction with a total yield equal to 150% of the ECEC, thus indicating formation of a patchy bilayer. By contrast, CLI_CA behaves completely differently since the formation of emi-micelle was achieved only at much higher speed (18000 rpm) and not earlier than 90 min of mixing.

Two zeolite-rich rock samples extracted from Campanian Ignimbrite tuff quarries, southern Italy, usually used as binding and anticaking agents in animal feeding, were characterized and tested in terms of their resistance in stomach, small and large intestine of pig, using a three step in vitro digestibility trial. The mineralogical composition and major and trace-elements analysis were performed after each digestion step using XRPD and ICP-OES techniques. The main zeolite phases identified are phillipsite and chabazite. Results showed that in vitro physical-chemical conditions (pH 2–3 and T 39 °C) the release of Pb and other elements from the zeolite structure is extremely low and due to the limited breakdown of the zeolite framework and glass/amorphous matter hydrolysis, by the gastric liquids. This aspect also suggests that zeolites, after the total permanence in the animal body digestive tract, can further perform their important function of cation exchanger, with also relevant relapses on the growth and health of the animal species, as well as on the environment. Moreover, the contact of zeolite material with liquids of small and large intestine leads to negligible release of undesirable elements, which are far less than those envisaged by the European Regulations.