Nicola Gargiulo

Preparation and characterization of polyethylenimine-modified mesoporous silicas as CO2 sorbents

Abstract Functionalization of MCM-48 and SBA-15 mesoporous silicas with polyethylenimine (PEI) has been achieved using the wet impregnation technique, and the obtained materials have been tested as media for CO 2 adsorption. Increasing PEI loading resulted in decreasing of the surface area and pore size of the potential adsorbents. PEI-modified mesoporous systems did not sorb any N 2 at 77 K, on the contrary both materials were able to sorb large amounts of CO 2 at 348 K and at very low pressure. At PEI loading of 50 wt% in MCM-48 and 44 wt% in SBA-15 adsorption capacities over 6 wt% were obtained. CO 2 desorption from the mesoporous silica samples under vacuum was close to 100%. These materials could be successfully used as sorbents to capture CO 2 after combustion or as H 2 stream purification media.

Gallium-containing mesoporous bioactive glass with potent hemostatic activity and antibacterial efficacy

Haemorrhage remains the leading cause of potentially survivable death in both military and civilian populations. Although a large variety of hemostatic agents have been developed, many of them have an inadequate capacity to induce hemostasis and are not effective in killing bacteria. In recent years, mesoporous bioactive glasses (MBGs) were found to be effective in inducing hemostasis. However, the materials may not be considered as ideal hemostats since they do not offer antimicrobial activity. The gallium ion (Ga+3) not only exhibits antibacterial properties but also accelerates the blood coagulation cascade. The aim of this study was to develop MBGs containing various concentrations of Ga2O3 (1, 2 & 3 mol%) via the evaporation-induced self-assembly (EISA) process and investigate whether the addition of Ga3+ would induce both hemostatic and antibacterial effects. The results indicated that the incorporation of lower Ga2O3 content (1 mol%) into the MBG system improved structural properties including the specific surface area, mesopore size and pore volume as well as the release of silicon and calcium ions. The bioactive glass was found to stimulate blood coagulation, platelet adhesion and thrombus generation and exerted an antibacterial effect against both Escherichia coli and Staphylococcus aureus. Likewise, Ga-doped MBGs showed excellent cytocompatibility even after 3 days, with the 1% Ga2O3-containing MBG attaining the best biocompatibility that render them safe hemostatic agents for stopping bleeding. This study demonstrated that the lowest Ga2O3-substituted MBG can be a potent candidate for controlling haemorrhage and wound infection.

Potency and Cytotoxicity of a Novel Gallium-Containing Mesoporous Bioactive Glass/Chitosan Composite Scaffold as Hemostatic Agents

Chitosan-based hemostats are promising candidates for immediate hemorrhage control. However, they have some disadvantages and require further improvement to achieve the desired hemostatic efficiency. Here, a series of 1% Ga2O3-containing mesoporous bioactive glass-chitosan composite scaffolds (Ga-MBG/CHT) were constructed by the lyophilization process and the effect of various concentrations of Ga-MBG (10, 30, and 50 wt %) on the hemostatic function of the CHT scaffold was assessed as compared to that of Celox Rapid gauze (CXR), a current commercially available chitosan-coated hemostatic gauze. The prepared scaffolds exhibited >79% porosity and showed increased water uptake compared to that in CXR. The results of coagulation studies showed that pure CHT and composite scaffolds exhibited increased hemostatic performance with respect to CXR. Furthermore, the composite scaffold with the highest Ga-MBG content (50 wt %) had increased capability to enhancing thrombus generation, blood clotting, and platelet adhesion and aggregation than that of the scaffold made of pure CHT. The antibacterial efficacy and biocompatibility of the prepared scaffolds were also assessed by a time-killing assay and an Alamar Blue assay, respectively. Our results show that the antibacterial effect of 50% Ga-MBG/CHT was more pronounced than that of CHT and CXR. The cell viability results also demonstrated that Ga-MBG/CHT composite scaffolds had good biocompatibility, which facilitates the spreading and proliferation of human dermal fibroblast cells even with 50 wt % Ga-MBG loading. These results suggest that Ga-MBG/CHT scaffolds could be a promising hemostatic candidate for improving hemostasis in critical situations.

A chromium-based metal organic framework as a potential high performance adsorbent for anaesthetic vapours

In this work, a chromium-based metal organic framework (Cr-MOF) was synthesized, characterized and tested for the adsorption of a model highly ozone-depleting anaesthetic (sevoflurane). Adsorption isotherms were measured at different temperatures e.g., 283, 298, 313 and 328 K on both Cr-MOF and a conventionally used reference adsorbent. At the temperatures used in this study, the Cr-based MOF showed a significantly higher sevoflurane (selected anaesthetic) equilibrium adsorption capacity compared to the reference sample, although adsorption on the selected MOF did not take place on all active sites (i.e., it did not expose its coordinatively unsaturated sites). Moreover, sevoflurane adsorption on Cr-MOF was found to be fully reversible in the 283–328 K temperature range, and the adsorbent was fully regenerated by vacuum treatment at ambient temperature. The semiempirical Sips model was successfully used to fit sevoflurane adsorption data, substantially confirming the phenomenological aspects of the process inferable from the experimental results.

Modeling pedogenization of zeolitized tuffs. II: medium-term weathering of phlegraean yellow tuff and red tuff with black scoriae by water and humic acids

An experimental pedology research program was started aiming at modeling the potential pedogenization of zeolitized tuffs. The present study deals with a medium-term weathering of Phlegraean Yellow Tuff (PYT, with phillipsite>chabazite) and Red Tuff with Black Scoriae (RTBS, with chabazite>phillipsite) under discontinuous treatment by water (W) and by humic acids (HA). Significant amounts of cations, increasing in the sequence Al<Fe<Mg<Ca, were extracted by both water and humic acids. The humic acids showed in all cases the highest extracting efficiency. All cations, especially calcium, were more easily removed from PYT than from RTBS. The only exception was iron which was preferentially removed from RTBS by HA. At the end of the experiment, smectite was not any more detected in the PYT residues. On the whole, the results indicate that PYT is more prone than RTBS to both humic acid and water weathering due to its different mineralogy.

Properties of zeolitized tuff/organic matter aggregates relevant for their use in pedotechnique. III: organic matter stability and exchange properties

Abstract A study was performed to evaluate the suitability of zeolitized tuffs to restore degraded soils. Ca-saturated Neapolitan yellow tuff or clinoptilolite-rich tuff from Turkey were mixed with organic matter either as humic matter (tannic acid, humic acids) or non-humic matter (polygalacturonic acid). Organic matter was strongly stabilized in clinoptilolite-rich tuff aggregates based on humic matter, whereas it was more easily oxidized in models with non-humic matter. Cation exchange capacity (CEC) was determined according to Ba/Mg-TEA method and by ammonium acetate procedure. The former method underestimated the CEC of the zeolitized tuffs, but was able to detect the contribution of organic matter to the CEC of aggregates. The latter method provided consistent CEC values for the zeolitized tuffs, but underestimated the exchange activity of the organic components of aggregates. CEC of aggregates including tannic acid was practically nil. Binding tannic acid to zeolite via Ca-bridges, results evidently in occlusion of zeolite pores.

Ion exchange kinetics and thermodynamics of hydrosodalite, a narrow pore zeolite

The ion-exchange properties of a synthetic hydrosodalite (Na-hS) have been investigated by kinetic and thermodynamic analysis of exchange reactions of the original sodium form for lithium, potassium and calcium forms. Kinetic curves, modelled by a Langmuir-type equation, revealed that exchange rate for lithium and for potassium are of the same order, whereas they are two order faster than for calcium. Thermodynamic analysis of the cation exchange isotherms pointed out that sodalite is selective for sodium over the other three cationic forms examined, which is consistent with the preference exhibited by the sodalite type for sodium environments, either in natural or in laboratory crystallization. Na/Li and Na/Ca exchanges are incomplete, whereas unexpectedly Na/K exchange turns out to be complete, even though K+ dimension exceeds the width of the access window to sodalite cages. The obtained results have been discussed in terms of Eisenman–Sherry theory, pointing out agreements and discrepancies.

Properties of zeolitized tuff/organic matter aggregates relevant for their use in pedotechnique. IIb: Structural characterization with emphasis on surface and porosity properties

Abstract A study is in progress aiming at characterizing the chemical, chemical-physical and structural properties of organo-zeolite aggregates relevant for their use in pedological technologies for soil restoration. This paper deals with the surface and porosity properties of organo-zeolite aggregates formed by Neapolitan Yellow Tuff (N), tannic acid (T), and Ca 2+ bridging ion, with different T/N ratios. T acted as a molecular plug. dramatically decreasing both the surface area and the micropore volume.

Titanium biomedical foams for osseointegration

Abstract: This chapter describes the state of the art of titanium foam for tissue attachment and, in particular, for implant osseointegration as the final application for bone tissue reconstruction. The chapter first introduces a description of the titanium alloys used for biomedical applications. Next, a section on the processing techniques for the foaming of the titanium or titanium alloys, as well as the surface treatments for the control of physical and chemical surface properties, is given. This overview aims at emphasizing the range of technological approaches to obtain functional biomedical foams. A section on methods for endowing titanium surfaces with biomolecules for tissue integration is also included. Finally, a survey on tissue response to material implantation is presented, with a focus on the titanium interfaces previously described.

Nanoporous Materials as H2S Adsorbents for Biogas Purification: a Review

Biogas is one of the most promising renewable sources of energy. However, it is also a gas mixture containing acidic gases, such as H2S, useless for energetic purposes, environmentally harmful and damaging for energy conversion devices. This review focuses on nanoporous materials as adsorbents of H2S for biogas purification processes. Cation-exchanged zeolites and impregnated activated carbons have been thoroughly studied since many years for this application, providing good results, in particular for what concerns activated carbons, despite having a limited regenerability. Amino-functionalized ordered mesoporous silicas produced very interesting results, both in terms of adsorption performances and regeneration capacity, but they are largely untested in large-scale “real-life” applications, and deserve further investigations, in particular for H2S and CO2 discrimination. On the contrary, despite reporting very good results, there are only few papers dealing with H2S adsorption on nanoporous metal organic frameworks.