Piergiulio Cappelletti

Phillipsite and Al-tobermorite mineral cements produced through low-temperature water-rock reactions in Roman marine concrete

Abstract Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000-year-old Roman harbor concrete. Pliny the Elder, however, in first century CE emphasized rock-like cementitious processes involving volcanic ash (pulvis) “that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass (fierem unum lapidem), impregnable to the waves and every day stronger” (Naturalis Historia 35.166). Pozzolanic crystallization of Al-tobermorite, a rare, hydrothermal, calcium-silicate-hydrate mineral with cation exchange capabilities, has been previously recognized in relict lime clasts of the concrete. Synchrotron-based X-ray microdiffraction maps of cementitious microstructures in Baianus Sinus and Portus Neronis submarine breakwaters and a Portus Cosanus subaerial pier now reveal that Al-tobermorite also occurs in the leached perimeters of feldspar fragments, zeolitized pumice vesicles, and in situ phillipsite fabrics in relict pores. Production of alkaline pore fluids through dissolution-precipitation, cation-exchange and/or carbonation reactions with Campi Flegrei ash components, similar to processes in altered trachytic and basaltic tuffs, created multiple pathways to post-pozzolanic phillipsite and Al-tobermorite crystallization at ambient seawater and surface temperatures. Long-term chemical resilience of the concrete evidently relied on water-rock interactions, as Pliny the Elder inferred. Raman spectroscopic analyses of Baianus Sinus Al-tobermorite in diverse microstructural environments indicate a cross-linked structure with Al3+ substitution for Si4+ in Q3 tetrahedral sites, and suggest coupled [Al3++Na+] substitution and potential for cation exchange. The mineral fabrics provide a geoarchaeological prototype for developing cementitious processes through low-temperature rock-fluid interactions, subsequent to an initial phase of reaction with lime that defines the activity of natural pozzolans. These processes have relevance to carbonation reactions in storage reservoirs for CO2 in pyroclastic rocks, production of alkali-activated mineral cements in maritime concretes, and regenerative cementitious resilience in waste encapsulations using natural volcanic pozzolans.

The characterization of natural gemstones using non-invasive FT-IR spectroscopy: New data on tourmalines

Fourteen samples of tourmaline from the Real Museo Mineralogico of Federico II University (Naples) have been characterized through multi-methodological investigations (EMPA-WDS, SEM-EDS, LA-ICP-MS, and FT-IR spectroscopy). The samples show different size, morphology and color, and are often associated with other minerals. Data on major and minor elements allowed to identify and classify tourmalines as follows: elbaites, tsilaisite, schorl, dravites, uvites and rossmanite. Non-invasive, non-destructive FT-IR and in-situ analyses were carried out on the same samples to validate this chemically-based identification and classification. The results of this research show that a complete characterization of this mineral species, usually time-consuming and expensive, can be successfully achieved through non-destructive FT-IR technique, thus representing a reliable tool for a fast classification extremely useful to plan further analytical strategies, as well as to support gemological appraisals.

The combined use of steam-treated bentonites and natural zeolites in the oenological refining process

Abstract Industrial minerals, particularly bentonites, have long been used in treatments to improve the stability and shelf life of white wines. We evaluated a new combination of rocks and minerals, including steam-treated bentonites and natural zeolites (chabazite and phillipsite), to greatly reduce the risk of protein and tartaric instability of wines. Detailed mineralogical, chemical and electrokinetic studies of these materials were conducted using powder X-ray diffraction (PXRD), X-ray fluorescence (XRF), microporosimetry, BET surface-area analysis and zeta-potential measurements. Several model wine solutions containing Bovine Serum Albumin (BSA) were prepared to evaluate the oenological performance of the rock/mineral combinations. UV-VIS spectrophotometry and ion chromatography were used to evaluate the degree of wine stabilization from the protein and tartaric point of view. The experimental results showed that steam treatment modifies both the microporosity and external surface area of the bentonite. These changes in surface area, along with creation of hydrophobic surfaces, significantly modified the behaviour of the steam-treated bentonites, requiring an increase in the amount of material necessary to bring the protein content to required levels. An important benefit derived from the use of steam-treated bentonites is that the pre-mixing with water before addition to wine is not necessary, as the material is readily dispersed. Finally, the addition of natural zeolites effectively decreased the potassium content, thereby improving the tartaric stability of white wines. In addition, this procedure results in minimal waste, as the bentonite-zeolite mixture can be reused as soil amendments in agriculture.

New data on Cu‑exchanged phillipsite: a multi‑methodological study

AbstractnThe cation exchange capacity of a natural phillipsite-rich sample from the Neapolitan Yellow Tuff, Southern Italy (treated in order to obtain a 95xa0wt% zeolite-rich sample composed mainly of phillipsite and minor chabazite) for Cu was evaluated using the batch exchange method. The sample had previously been exchanged into its monocationic form (Na), and then used for the equilibrium studies of the exchange reactionxa02Na+xa0⇆xa0Cu2+. Reversibility ion exchange tests were performed. The isotherm displays an evident hysteresis loop. Interestingly, the final Cu-exchanged polycrystalline material was green-bluish. Natural, Na- and Cu-exchanged forms were analyzed by X-ray powder diffraction, and the Cu-phillipsite was also investigated by transmission electron microscopy (TEM). Structure refinement of Cu-phillipsite was performed by the Rietveld method using synchrotron data, and it indicates a small, but significant, fraction of Cu sharing with Na two–three independent extra-framework sites. The TEM experiment shows sub-spherical nano-clusters of crystalline species (with average size of 5xa0nm) lying on the surfaces of zeolite crystals or dispersed in the amorphous fraction, with electron diffraction patterns corresponding to those of CuO (tenorite-like structure) and Cu(OH)2 (spertiniite-like structure). X-ray and TEM investigations show that Cu is mainly concentrated in different species (crystalline or amorphous) within the sample, not only in phillipsite. The experimental findings based on X-ray and TEM investigations, along with the hysteresis loop of the ion exchange tests, are discussed and some general considerations about the mechanisms of exchange reactions involving divalent cations with high hydration energy are provided.

Petrogenesis and deformation history of the lawsonite-bearing blueschist facies metabasalts of the Diamante-Terranova oceanic unit (southern Italy)

Handling Editor: Donna Whitney Abstract The Neotethyan oceanic Diamante-Terranova unit (DIATU; southern Apennines– Calabria–Peloritani Terrane system) includes basic rocks that during the Cenozoic were subducted and metamorphosed to lawsonite-blueschist facies conditions. Petrological and structural observations (both at the mesoand micro-scale) show that lawsonite growth was continuous during three distinctive ductile deformation stages (D1–D3). These likely occurred close to the metamorphic peak, estimated at 350–390°C and 0.9–1.1 GPa, producing an equilibrium assemblage made of blue Na-amphibole, lawsonite, chlorite and pumpellyite. Locally, pods dominated by quartz and epidote (plus chlorite, calcite and green Ca-amphibole) developed at similar conditions (350–370°C, 0.8–0.9 GPa). Post-peak evolution during the final exhumation of the DIATU along the subduction channel, also consisted of three deformation stages, defined by folding (D4) and normal faulting (D5) and finally by strike-slip faulting (D6), affecting both the blueschist unit and the unconformably overlying Tortonian conglomerates. Vorticity analysis on syn-tectonic lawsonite crystals indicates that severe flattening occurred during the D2 stage, with a significant secondary non-coaxial strain component along the W–E plane. This is associated with an eastward tectonic vergence, consistent with the subsequent D3 and D4 folding stages characterized by a dominant ENE tectonic transport. It is suggested that exhumation started from the D2 stage and continued during D3 at similar HP/ LT metamorphic conditions. The widespread occurrence of unreacted lawsonite crystals suggests that exhumation was very fast and supports the idea that concurrent ductile deformation might play a role in its preservation.

Surface-modified phillipsite-rich tuff from the Campania region (southern Italy) as a promising drug carrier: An ibuprofen sodium salt trial

Abstract The encapsulation and delivery of drugs often involves the use of expensive microporous materials, and we have investigated the potential for natural zeolites from the widespread volcanic formations of southern Italy as alternatives to these carriers. Surface-modified natural zeolites (SMNZs) with diverse micellar structures (patchy and complete bilayers) were obtained by using different cationic surfactants [cetylpyridinium chloride (CP-Cl), benzalkonium chloride (BC-Cl), hexadecyltrimethylammonium chloride (HDTMA-Cl), and bromide (HDTMA-Br) with phillipsite-rich tuff from the Campania region (southern Italy)]. Loading and release kinetics tests of sodium ibuprofen (IBU) were carried out with organo-phillipsite composites using Fourier transform infrared spectroscopy (FTIR) and thermal analysis coupled with evolved gas analysis (EGA). Results from these tests were mathematically modeled to evaluate IBU adsorption and release mechanisms. The maximum loaded amount of IBU was attained for organo-phillipsite modified with HDTMA-Br (PHB), which showed a complete bilayer micellar structure. Whenever a patchy bilayer micellar structure formed, the lowest adsorptions of IBU were observed. Equilibrium adsorption results were fit using Langmuir, Sips, and Toth models. Pseudo-first-order and pseudo-second-order fits to the loading kinetic data provided significant goodness of fit. Good fits to the release kinetic data were obtained using first-order and Weibull equations, shedding new light on the release mechanism of IBU from phillipsite. The active amount of IBU on the modified zeolite surface was almost totally available for pharmaceutical purposes.