Mariano Mercurio

Anion exchange selectivity of surfactant modified clinoptilolite-rich tuff for environmental remediation

Lately, the functionalization of industrial minerals with high technological properties, such as natural zeolites, is shaping as a promising approach in environmental sphere. In fact, under the specific conditions, the surface functionalization via adsorption of cationic surfactants reverses the surface charge of the mineral, enabling zeolites to simultaneously interact either with organic contaminants or inorganic anions. This aspect allows zeolites to be used in the remediation of contaminated fluids. The present research shed new light on some still not fully understood aspects concerning exchange kinetics such as anion-exchange mechanisms and selectivity of surface modified minerals. For this purpose the mineralogical characterization and the surface properties evaluation (X Ray Powder Diffraction, chemical analysis, thermal analysis, ECEC and AEC) of a clinoptilolite-rich tuff were performed, and the anion exchange isotherms of the sample, modified with hexadecyltrimethylammonium chloride or bromide (HDTMA-Cl/-Br), were determined. Ion-exchange equilibrium data of uni-uni valent reaction were obtained by solutions containing Br(-), Cl(-), NO3(-) or ClO4(-). Liquid phase was analysed via high performance liquid chromatography. Thermodynamic quantities (Ka and ΔG(0)) were determined and compared with the Hofmeister series. The value of the ECEC, calculated in batch conditions, was about 137 mmol/kg, in good agreement with that evaluated in dynamic conditions, while the AEC data were different for the SMNZ-Br and -Cl samples, amounting to 137 and 106 mmol/kg, respectively, thus indicating a different compactness of the bilayer formed in the two cases. Moreover, the anion isotherm results and the mathematical evaluation of the thermodynamic parameters, demonstrated the good affinity of SMNZ-Br towards chloride, nitrate and perchlorate, and of SMNZ-Cl for nitrate and perchlorate, also endorsing the possibility of using the same thermodynamic approach developed to describe cation exchange selectivity in zeolites. Finally, it was also verified that the zeolite modified with HDTMA-Cl is able to better exploit its anion exchange capacity compared to the same zeolite modified with HDTMA-Br.

Surface modified natural zeolite as a carrier for sustained diclofenac release: A preliminary feasibility study

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 5h through a mechanism prevalently governed by anionic exchange with a rapid final phase.

Adsorption of the mycotoxin zearalenone by clinoptilolite and phillipsite zeolites treated with cetylpyridinium surfactant.

In this study, organozeolites were prepared by treatment of the natural zeolites (clinoptilolite and phillipsite) with cetylpyridinium chloride (CP) equivalent to 50 and 100% of their external cation exchange capacities (ECEC). Organoclinoptilolites (ZCPs) and organophillipsites (PCPs) were characterized by FTIR spectroscopy, thermal analysis, determination of the point of zero charge and zeta potential. Adsorption of zearalenone (ZEN) by ZCPs and PCPs at pH 3 and 7 was investigated. Results showed that adsorption of ZEN increases with increasing amounts of CP at the zeolitic surfaces for both ZCPs and PCPs but the adsorption mechanism was different. Adsorption of ZEN by ZCPs followed a linear type of isotherm at pH 3 and 7 while ZEN adsorption by PCPs showed non linear (Langmuir and Freundlich) type of isotherm at both pH values. Different interactions between the ZEN molecule (or ion) and ZCPs and PCPs occurred: partition (linear isotherms) and adsorption in addition to partition (non linear isotherms), respectively. For the highest level of organic phase at the zeolitic surfaces, the maximum adsorbed amount of ZEN was 5.73mg/g for organoclinoptilolite and 6.86mg/g for organophillipsite at pH 3. Slightly higher adsorption: 6.98mg/g for organoclinoptilolite and 7.54mg/g for organophillipsite was achieved at pH 7. The results confirmed that CP ions at both zeolitic surfaces are responsible for ZEN adsorption and that organophillipsites are as effective in ZEN adsorption as organoclinoptilolites.

Thin walled pottery from Alife (Northern Campania, Italy)

The ancient town of Allifae (modern Alife) represents one of the most interesting settlements of the Northern Campania area and together with the ancient city of Cales , was a thriving production centre of pottery. Excavations carried out inside the city wall, near the south gate, the so called, Porta Fiume, unearthed a huge dump of thin-walled ware, where the most abundant forms were cups and beakers, decorated with grooves or rouletting. The dump has been dated late Augustan/Tiberian age and the thin-walled vessels found can be identified with similar wares from Allifae, Cubulteria, Caiatia and perhaps Neapolis. Horace in his Sermones (II, 8,39) cited the Allifana beakers (described as fictiles ac subtiles by a Horace scholiast) and they could possibly be identified with the thin-walled wares produced in Allifae. If this the case, then the thin-walled vessels produced in Allifae were known in Rome as early as the end of I century B.C. In order to investigate and characterize the Allifae thin-walled pottery, twenty-one samples were selected and mineralogical-petrographic analyses (OM, XRD, XRF and SEM/EDS) were carried out. The clayey raw material used was a low-CaO alluvial clayey deposit from the Middle Valley of the Volturno River. The potters probably handled the sediment by a levigation process in order to remove the coarser grains, and making the clay suitable to produce such thin walls. Comparison with other regional production of thin-walled pottery allowed us to strictly distinguish the Allifana beakers.

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.

May the use of Italian volcanic zeolite-rich tuffs as additives in animal diet represent a risk for the human health?

IIn Europe the use of zeolite-rich tuffs as additives in animal feeding is well established and ratified by legislation. Quality checks on batches are mandatory to determine the undesirable elements such as lead that, among the heavy metals, plays a primary role for its devastating effects on the quality life of living beings. The present study aimed at determining the total and leached Pb for different samples of Campanian zeolite-rich tuffs related to the most relevant volcanic eruptions (Campanian Ignimbrite and Neapolitan Yellow Tuff). Other samples deriving from other Italian and extra-european exploitation sites were used for comparative tests. The research demonstrated that lead occurrence is linked to the specific paragenesis of the investigated rocks whereas the leached Pb largely depends on the type of zeolite and its amount. It was also established that the use of Campanian zeolite-rich tuffs as additives in animal feeding can be tolerated as these materials are well comparable to analogous products from the minerogenetic point of view such as the clinoptilolite of volcanic origin.

Non-invasive FTIR spectroscopy: new preliminary data for the identification of mineralogical phases forming Cultural Heritage materials

This paper focuses on the application of external reflection Fourier Transform Infrared spectroscopy for the classification of some minerals commonly used as gemstones and mineral collection: quartz (colourless, tourmalinated and smoky varieties), calcite and aragonite.The results highlight the differences between reflectance and absorbance spectra, allowing a faster, cheaper and non-destructive approach for the identification of monocrystalline minerals.

The “Tufo Giallo della Via Tiberina” (Sabatini Volcanic District, Central Italy): a complex system of lithification in a pyroclastic current deposit

The Sabatini Volcanic District belongs to the Roman magmatic province of Central Italy, and the Tufo Giallo della Via Tiberina was one of the most voluminous pyroclastic flow-forming eruptions in this district. Post-depositional processes strongly affected this pyroclastic flow deposit leading to the crystallization of different authigenic phases (chabazite, phillipsite, feldspar). A field volcanological survey, along with a careful mineralogical characterization of a large amount of samples of the lithified facies, allowed us to reconstruct a type section primarily based on the amounts of the main authigenic phases. Chabazite always prevailed over phillipsite throughout the entire section, although in the innermost portions of the deposit, where temperatures remained high, chabazite mostly converted into a more stable phase such as an adularia-like phase. In addition to the zeolitization process, the fairly strong mechanical properties of this tuff can be also ascribed to the diffuse occurrence of microcrystalline calcite, which re-precipitated as a secondary phase after the dissolution of carbonaceous clasts.

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.