Andrey Ryzhikov

Energetic performances of pure silica STF and MTT-type zeolites under high pressure water intrusion

Experimental water intrusion–extrusion isotherms were performed at room temperature on two pure silica MTT- and STF-type hydrophobic zeolites (zeosils) with 1D channel and cage pore systems, respectively by applying or releasing a high hydraulic pressure. These zeosils were obtained by hydrothermal synthesis in fluoride medium and characterized by structural and physicochemical methods before and after water intrusion. The system “MTT-type zeosil–water” displays a spring behavior with an intrusion pressure of 176 MPa and a stored energy of 5.3 J g−1. No influence of water intrusion on the structure of MTT-type zeosil was found. The “STF-type zeosil–water” system shows a combination of shock-absorber and bumper behavior in the first cycle with an intrusion pressure of 51 MPa. Nevertheless in the following cycles the system demonstrates a spring behavior with an intrusion pressure of 38 MPa. Such behavior can be explained by the formation of silanol groups under intrusion in some pores confirmed by NMR spectroscopy and TG data.

Organometallic Synthesis of CuO Nanoparticles: Application in Low-Temperature CO Detection

A metal-organic approach has been employed for the preparation of anisotropic CuO nanoparticles. These nanostructures have been characterized by transmission and high resolution transmission electron microscopy, field-emission scanning electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The CuO nanoparticles have been deposited as gas-sensitive layers on miniaturized silicon devices. At an operating temperature of 210 °C, the sensors present an optimum response toward carbon monoxide correlated with a fast response (Rn) and short recovery time. A high sensitivity to CO (Rn≈150 %, 100 ppm CO, RH 50 %) is achieved. These CuO nanoparticles serve as a very promising sensing layer for the fabrication of selective CO gas sensors working at a low temperature.

Influence of LiCl aqueous solution concentration on the energetic performances of pure silica chabazite

In order to study the energetic performances of different “pure silica chabazite–LiCl aqueous solution” systems, intrusion–extrusion experiments were performed under high pressure. Depending on the LiCl concentration in the aqueous medium (0 M, 5 M, 10 M, 20 M), an increase of the stored (4.4, 9.9, 13.5, 24.3 J g−1) and restored (2.6, 8.1, 11.8, 20.5 J g−1) energies are observed. Therefore, compared to the “pure silica CHA–H2O” system, the stored energy is increased by 5.5 times for the “pure silica CHA–20 M LiCl” one. The zeolite samples were characterized (XRD, TG, NMR spectroscopy, N2 adsorption and SEM) before and after the intrusion–extrusion process in order to better understand the influence of the LiCl concentration on the system behavior.

Ultra-sensitive SnO 2 gas sensors based on hierarchical octahedra

The controlled hydrolysis of Sn11 precursor ([Sn(NMe)2]2) yields micrometric Sn3O2(OH)2 octahedra, formed by a self-assembly process. The water content and alkylamine surfactants are major parameters for the growth process. These structures have been employed to prepare highly sensitive gas sensors, which present 7% variation of their resistance at only 0.25 ppm CO.

Porous sorbents for the capture of radioactive iodine compounds: a review

The number of studies on the capture of radioactive iodine compounds by porous sorbents has regained major importance in the last few years. In fact, nuclear energy is facing major issues related to operational safety and the treatment and safe disposal of generated radioactive waste. In particular during nuclear accidents, such as that in 2011 at Fukushima, gaseous radionuclides have been released in the off-gas stream. Among these, radionuclides that are highly volatile and harmful to health such as long-lived 129I, short-lived 131I and organic compounds such as methyl iodide (CH3I) have been released. Immediate and effective means of capturing and storing these radionuclides are needed. In the present review, we focus on porous sorbents for the capture and storage of radioactive iodine compounds. Concerns with, and limitations of, the existing sorbents with respect to operating conditions and their capacities for iodine capture are discussed and compared.

Heterogeneous lyophobic systems based on pure silica ITH-type zeolites: high pressure intrusion of water and electrolyte solutions

The energetic performances of pure silica ITH-type zeolites were studied by high pressure intrusion–extrusion in water and LiCl aqueous solutions at different concentrations. When pure water was intruded, a bumper behavior was exhibited with an intrusion pressure of 82 MPa and an absorbed energy of 6.6 J g−1. Changing the intruded liquid from water to LiCl aqueous solutions, an increase of the intrusion pressure was observed with 119, 175 and 280 MPa for 5 M, 10 M and 20 M LiCl aqueous solutions, respectively. The energy that the latter system could absorb (30.8 J g−1) was among the highest ever reported. A change in the behavior with LiCl concentration was also observed. The “ITH-type zeosil–20 M LiCl solution” system demonstrated a combination of bumper and shock-absorber behaviors, whereas a bumper behavior was displayed for water and the other LiCl aqueous solutions. All the zeolite samples were characterized before and after intrusion–extrusion experiments (XRD, SEM, N2 adsorption–desorption, TG and NMR analysis) in order to understand the influence of LiCl concentration on the “zeosil–liquid” system behavior.

Intrusion–extrusion of electrolytic solutions in zeolites for energy storage

Rossella Arletti1, Laura Ronchi2, Simona Quartieri3, Giovanna Vezzalini4, Andrey Ryzhikov2, Habiba Nouali2, Jean Daou2, Joel Patarin2 1Dipartimento Di Scienze Della Terra, Torino, Italy, 2Université de Strasbourg (UDS), Université de Haute Alsace (UHA), Equipe Matériaux à Porosité Contrôlée (MPC), Institut de Science des Matériaux de Mulhouse (IS2M), UMR CNRS 7361,, Mulhouse, F-68093, France, 3Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra, Università di Messina, Messina S. Agata, I98166, Italy, 4Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, Modena, Modena, I41100, Italy E-mail: rossella.arletti@unito.it