Sabrina Portofino

Steam gasification of waste tyre: Influence of process temperature on yield and product composition

An experimental survey of waste tyre gasification with steam as oxidizing agent has been conducted in a continuous bench scale reactor, with the aim of studying the influence of the process temperature on the yield and the composition of the products; the tests have been performed at three different temperatures, in the range of 850-1000°C, holding all the other operational parameters (pressure, carrier gas flow, solid residence time). The experimental results show that the process seems promising in view of obtaining a good quality syngas, indicating that a higher temperature results in a higher syngas production (86 wt%) and a lower char yield, due to an enhancement of the solid-gas phase reactions with the temperature. Higher temperatures clearly result in higher hydrogen concentrations: the hydrogen content rapidly increases, attaining values higher than 65% v/v, while methane and ethylene gradually decrease over the range of the temperatures; carbon monoxide and dioxide instead, after an initial increase, show a nearly constant concentration at 1000°C. Furthermore, in regards to the elemental composition of the synthesis gas, as the temperature increases, the carbon content continuously decreases, while the oxygen content increases; the hydrogen, being the main component of the gas fraction and having a small atomic weight, is responsible for the progressive reduction of the gas density at higher temperature.

End-of-Waste SiC-Based Flexible Substrates with Tunable Electrical Properties for Electronic Applications

We demonstrated the suitability of polymer composites filled with silicon carbide (SiC) powders derived from a recycling process for applications in electronic devices manufacturing. SiC powders have been synthesized from the process byproducts and used as fillers in the formulation of polystyrene (PS)/SiC composites, which have been used in the preparation of substrates using the solution-casting technique. Different substrates have been prepared by changing the concentration of SiC in the composite in the range from 6.7 to 67 wt % and used in simple electronic devices by performing gold contacts in both planar and stacked configurations. The electrical behaviors of both stacked and planar devices were investigated in direct current (DC) and alternate current (AC) regimes. The experimental results showed that charge percolation could be considered an explanation for the abrupt change in the differential conductivity observed around 30 wt %. Fowler-Nordheim tunneling at high fields has been found to be compatible with static characteristics and with high-frequency AC measurements and, therefore, charge tunneling between SiC islands has been proposed as the physical mechanism provoking the changes in charge transport in the substrates investigated. From this first experimental analysis, it appears that SiC/PS composites could suit their use in tunneling-gate dielectrics (i.e., in transistors suitable for their applications in nonvolatile random-access memory) for low concentrations or as a continuous semiconducting media when SiC is dispersed in high-concentration composites.

Nonvolatile RRAM cells from polymeric composites embedding recycled SiC powders

Silicon carbide powders have been synthesized from tires utilizing a patented recycling process. Dynamic light scattering, Raman spectroscopy, SEM microscopy, and X-ray diffraction have been carried out to gather knowledge about powders and the final composite structure. The obtained powder has been proven to induce resistive switching in a PMMA polymer-based composite device. Memory effect has been detected in two-terminal devices having coplanar contacts and quantified by read-write-erase measurements in terms of level separation and persistence.

Preliminary experimental results of the hierarchical growth of carbon nanotubes on recovered carbon fibers by CCVD method

9th International Conference on Times of Polymers and Composites: From Aerospace to Nanotechnology

New Designed Procedure for G/sio2/sic Nano-heterojunctions Growth on Recycled 3c-sic Powder

Few layer graphene/SiO2/SiC (G/SiO2/SiC) core-layers-sheath nano-heterojunctions were obtained by a new easy and cheap designed procedure by thermal annealing at atmospheric pressure and low temperature on 3C-SiC powder derived from exhausted activated carbon. Recycled SiC was chosen as growth substrate to realize a convenient process and to increase the added value of the recycled, combining the favourable properties of different substances. SiC powder and the advanced materials obtained were carefully characterized by the combining use of different techniques: transmission electron microscopy (TEM) with EDAX probe, scanning electron microscopy (SEM), X-ray diffraction analysis, Raman spectroscopy, thermogravimetric analysis coupled with quadrupole mass detector (TG-DTG-MASS).

Synthesis of Ceramic Materials from Waste Residues

In the frame of a wide research program devoted to the matter recovery from waste by means of thermal processes, particular efforts have been put into the study of biomasses and waste residue of peculiar composition, which could be used as precursors of ceramic materials. Rice shells are waste biomasses coming from the purification process of rice, which show a high carbon and silica content. The exploitation of these peculiarity promoted a series of experimental activities, aimed at the production of ceramic materials through high temperature carbothermal synthesis reactions. The synthesis products were characterized by X Ray Diffraction (XRD) and scanning electron microscopy (SEM) and the data confirmed the production of ceramic silicon nitride (Si3N4) at high yield and purity, under the adopted process parameters.