D. Vuono

Synthesis Methods of Carbon Nanotubes and Related Materials

The challenge on carbon nanotubes is still the subject of many research groups. While in the first years the focus was on the new synthesis methods, new carbon sources and support materials, recently, the application possibilities are the principal arguments of the studies. The three main synthesis methods discussed in this review are the arc discharge, the laser ablation and the chemical vapour deposition (CVD) with a special regard to the latter one. In the early stage of the nanotube production the first two methods were utilized mainly for the production of SWNTs while the third one produced mainly MWNTs. The principle of CVD is the decomposition of various hydrocarbons over transition metal supported catalyst. Single-walled (SWNT), multi-walled (MWNT) and coiled carbon nanotubes are produced. In some case, interesting carbonaceous materials are formed during the synthesis process, such as bamboo-like tubes, onions, horn-like structures. In this paper, we refer to the progresses made in the field of the synthesis techniques of carbon nanotubes in the last decade.

Synthesis and characterization of the microporous titanosilicates ETS-4 and ETS-10

In the last years the interest in new zeolitic structures has increased. Some of these materials possess improved catalytic and adsorptive properties in comparison with the classical aluminosilicates. Among these materials are the AlPOs which opened new roads in the study of zeotypes. Subsequently, the study of titanium- and silicon-based molecular sieves was deepened. Among the numerous synthesized structures ETS-10 is a totally synthetic one while ETS-4 is the synthetic counterpart of the mineral zorite. In this paper a complete study is devoted to the ETS-10 and ETS-4 crystallization fields as a function of the quantities of Na2O and TiO2 in the initial gel. The influence of the initial pH on the two phases was also studied. The crystallization curves as a function of time for ETS-10 and ETS-4 with different initial Na and Ti contents were determined and analyzed. The SEM pictures allowed one to determine the morphology of the two ETS phases. Their compositions were determined by chemical analysis, and local structural characteristics were derived from NMR analysis.

Concrete products with waste's plastic material (bottle, glass, plate)

Plastic material is not easily biodegradable even after a long period, in fact a wide variety of waste materials can be utilized as inert in matrix cement. In this paper we have focused the attention on the use of plastic material particles incorporated as aggregate in concrete and we have evaluated the chemical, physical and mechanical properties

From hydrophobic to hydrophilic polyvinylidenefluoride (PVDF) membranes by gaining new insight into material's properties

This work provides an easy and versatile strategy to manufacture novel polyvinylidenefluoride (PVDF) membranes by solution casting and phase separation techniques displaying tailored physicochemical and microstructural features depending on the opportune combination of functionalization by blending chemical additives (multiwalled carbon nanotubes, MWCNTs) and manufacturing procedure. The systematic study of the effect of (i) polymer concentration, (ii) use of pore forming additives (LiCl), and (iii) type and concentration of MWCNTs, on the PVDF crystalline composition and membrane microstructure, highlights the strong relationships of these parameters with the wettability, fouling and transport attributes of the formed membranes. The results provide the key to discriminate membrane preparation conditions favoring hydrophilic, low fouling, and highly selective PVDF–MWCNTs membranes, for water-treatment applications in pressure-driven membrane operations, from conditions favoring the formation of hydrophobic and waterproof membranes, to be used in the membrane contactors field. Also, they open exciting perspectives for a more effective development of PVDF-based nanostructured membranes for advanced separations based on a comprehensive investigation and understanding of materials properties.

Synthesis and ion exchange properties of the ETS-4 and ETS-10 microporous crystalline titanosilicates

This paper deals with the ETS-4 and ETS-10 titanosilicates synthesised hydrothermally using titanium (IV) chloride as titanium source, without any organic additives and no seeding. The starting materials were gels of molar composition: 1.49SiO 2 :xNa 2 O:yTiO 2 :0.6KF: 1.28·xHCl:39.5H 2 O, where: 0.5≤x≤2.5 and 0.1≤y≤0.4. By varying the amount of Na 2 O and TiO 2 respectively, the crystallization domains of the titanosilicates mentioned above were found. The optimal gel composition for crystallization was found kinetically. A high purity and crystallinity ETS-10 was obtained for 1.0 mole Na 2 O and 0.2 mole TiO 2 . The ETS-4 and ETS-10 phase mixture is due to a co-crystallization process. The physico-chemical characterisation of these synthesised materials was carried out by XRD, SEM, TG/TDG/DSC, EDS and sorption of 137 Cs and 60 Co radionuclides.

Study of the thermal dehydration of metal-exchange ETS-10 titanosilicate

The ion exchange of nickel, cobalt and copper on ETS-10 and the dehydration kinetics of metal-exchanged ETS-10 titanosilicate were studied by means of X-ray diffraction, scanning electron microscopy and thermal analyses. The number of water molecules in the metal-exchaned ETS-10 is higher than in parent ETS-10 and the activation energies for dehydration vary in the sequence: ETS-10> Ni-ETS-10 >Co-ETS-10 >Cu-ETS-10. A part of copper cations precipitate on the strong basic surface of ETS-10 as claringbullite (Cu4Cl(OH)7·0.5H2O). The differential thermogravimetry (DTG) curves show that the maxima of dehydration temperature are shifted towards lower temperature as the metal concentration increases.

Influence of zirconium on the crystallisation kinetics of ETS-4 molecular sieves

The scope of the paper is to synthesize and characteirze ETS-4 molecular sieve starting from gels containing titanium and zirconium: xNa2O-0.2TiO2-0.6KF-yZrO2-1.28xHCl-1.49SiO2-39.5H2O with 0.5≤x≤1.5 and 0.0≤y≤0.2. The study is based on the physicochemical characterization of the various products and on the determination of the kinetic parameters.

Ionic exchange and thermal characterisation of different cation exchanged forms of ETS-4

Abstract The main object of this paper is the study of thermal stability and ionic exchange capacity of ETS-4 exchanged with different cations. The ETS-4 molecular sieve sample was exchanged with Li + , Na + , K + and NH 4 + . Different cation exchanged forms of ETS-4 were heated at different temperatures for 2 hours and the degree of cristallinity was determined by X-ray diffraction. Moreover, an exchange was effectuated with solutions at different concentrations in order to determine the ionic exchange capacity of different ionic forms of ETS-4.

Synthesis and Characterisation of Hydroxyapatite

The aim of this study is to synthesise hydroxyapatite by hydr othe mal reactions and to compare the resultant pure phases obtained in static and dynamic conditions. Introduction The study of biomaterials begins in the XX th century, but in the last 25-30 years it shows a significant development. Polymer materials are replacing organs, but they do not sti mulate the growth of bonetissue. This function is done, indeed, by ceramic materials. Those materials have biocompatibility, bioactivity and good mechanical properties. The main applications of thes e materials are: prosthesis, as hip prosthesis, knee prosthesis and others [1]. The use of materials like bone tissue offers good potentiality. Calcium phosphate based materials are considered an a pproach of bio-mimetic type. The mostly used in biomaterials are hydroxyapatite (HA), octacal cium phosphate (OCP) and ß-tricalcium phosphate (ß-TCP). In the years ’90, HA was used to coat metallic pr osthesis, increasing the biocompatibility with bone tissue. In 1992 Menabue et al. studied the producti n of bioceramics with controlled porosity [2].In 1995 Fabbri et al. synthesised hydroxyapatit e-based porous aggregates [3]. In 1999 Martinetti and Nataloni studied biomimetism in maxillo facial surgery [4]. In 1996 Ito et al. synthesised HA from hydrothermal synthesis using hydroxyapatite disk as see ds [5]. Experimental HA is synthesised using CaHPO 4 (Aldrich), commercial HA (HAcom., Aldrich) and distilled water. The synthesis procedure is the following: 2.5 g of CaHPO 4 and 0.15 g of HA in powder are mixed in 300 ml of distilled water. The mixture is homogenised for 15 minutes a nd inserted into PTFE-lined Morey type inox steel autoclaves of 50 cm . The autoclave is put in a thermoventilated oven at 100°C. The synthesis is carried out in two ways: (1) in static condit ions; (2) in dynamic conditions. The powder extracted from the autoclave at different times of synthes is is recovered by filtration, washed with distilled water and dried at about 100°C for 24 h. The samples w ere identified by powder XRD on a Philips PW1830 diffractometer using CuK α radiation. The scanning speed was 0.02°s -1 in the 5-45° 2θ range. The morphology of the HA is determined by scanning electro n microscope MICROSPEC WDX-2A using a 25 KV accelerating potential. Chemical microanalysis was carried out by EDS ZAF-ZAF-4/FLS analy sis. Results and discussion The study was carried out to optimise the amounts of reagents needed to produce HA in powde r. The initial system is the following (in moles): xCaHPO 4 – yH2O – 1.5*10 -4 HAcom where: 1.0*10≤x≤2.6*10 and 11.7≤y≤21.7. The amount of HA com is considered as an optimal parameter to start the reaction and was not varied in this study. The research is carried out using two synthesis conditions: synthesi s of HA with stirring (dynamic conditions) and without stirring (static conditions). Figure 1 shows the crystallisation field of HA produced in static conditions as a function of the amounts of CaHPO 4 and H2O. Key Engineering Materials Online: 2003-12-15 ISSN: 1662-9795, Vols. 254-256, pp 43-46 doi:10.4028/www.scientific.net/KEM.254-256.43

Polyvinylidenefluoride/carbon nanotubes mixed matrix membranes with tailored properties

Membrane operations are promising tools for efficient and environmentally friendly separations. However, the development of advanced membranes with tailored properties is a key issue to be addressed in order to better exploit the potentialities of membrane-based separations. An important approach toward this aim is the development of mixed matrix membranes in which an organic and an inorganic phase coexist in order to have synergic effects on membrane properties. The peculiar properties of carbon nanotubes (CNTs) such as high electrical and thermal conductivity, high strength and unique transport properties, has motivated a considerable effort to produce CNT-polymer composites in order to engineer membrane properties. In this work the roughness, wettability, morphology, crystalline phase and pore size of polyvinylidenefluoride (PVDF) membranes were tailored working on the membrane preparation conditions, as well as, by blending the polymer with multiwalled carbon nanotubes (MWCNTs). A study on the effect ...