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This study reports on the synthesis and characterization of sulfated Al 2 O 3 and of composite membranes, prepared by dispersing the functionalized oxide in Nafion, acting as electrolytes in proton-exchange membrane fuel cells. Different synthetic routes were explored to obtain nanometric alumina particles with sulfate groups. Structural and morphological characteristics of the inorganic compounds and the nature of the bond of the sulfates with the oxide were investigated by x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, N 2 adsorption and thermal gravimetric analysis. Key properties of the hybrid membranes were elucidated in terms of thermal characteristics, water uptake and ionic exchange capacity. Functionality of the nanocomposite membranes, compared with plain Nafion, was tested in hydrogen-fed fuel cells. Polarization and power density curves and in-situ electrochemical impedance spectroscopy were accomplished to evaluate the effect of temperature on the cell performance. It is shown that well-addressed variations in the synthetic routes are able to determine different morphologies and dimensions of the particles and different degrees of functionalization. The incorporation of alumina in Nafion changes the characteristics of the membrane, with special regard towards hydration. In-situ fuel cell electrochemical tests reveal improved electrode-composite membrane interface properties as the working temperature of the cell increases. [ABSTRACT FROM AUTHOR]

Starting from the knowledge of ancient materials, the present work aims at developing green eco-friendly restoration mortars. A multi-step approach is proposed for this purpose including a characterization of ancient mortars, followed by that of the raw materials, ending with an in-depth one of the new products. Therefore, new mortars have been produced following the ancient recipe used in the construction of the Aqua Traiana aqueduct (Rome, 2nd century CE). Minero-petrographic and mechanical features, along with the assessment of porosity, water absorption, hydraulic index, and the evaluation of phytotoxicity toward microalgae cells, have been considered to evaluate the new products. The results proved that the nature of the aggregate and of the binder influence the porosity and the formation of newly reaction phases. The growth of these minerals creates a porous network inside the binder paste which shows an efficient reactivity in the formation of C-S-H compounds. [ABSTRACT FROM AUTHOR]

Aqua Traiana is an ancient Roman aqueduct, built to supply water to the ancient city of Rome and still working nowadays. This work is focused on the characterization of its mortars, and in particular the binders, to identify the reasons of such a durable resistance. Samples collected inside the aqueduct were analysed by Optical Microscopy (OM) in thin sections, X-ray Powder Diffraction (XRPD), Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDS), High Resolution Field Emission Scanning Electron Microscopy (HR-FESEM-EDS), Electron Microprobe (EMPA), Differential Scanning Calorimetry coupled with Thermogravimetric Analysis (DSC-TGA), Fourier-Transform Infrared spectroscopy (FTIR), X-ray Absorption Near Edge Structure (XANES) spectroscopy and N 2 adsorption/desorption measurements. The presence of an amorphous gel-like C-(N,K)-A-S-H binder and the complete absence of calcite in Trajan Age samples constitute a unique case, and may be the reason of the high hydraulicity of the mortar. Establishing how these features were produced could allow them to be replicated in high-durability and high-compatibility restoration mortars. • Ancient mortars from Aqua Traiana are characterised by a multi-analytical approach. • Trajan mortars have pozzolanic aggregate, amorphous gel-like binder without calcite. • The absence of calcite in Trajan samples constitutes a unique case in history. • The amorphous binder gives better hydraulicity and mechanical strength. • High-durability and green mortars could be produced from ancient recipes. [ABSTRACT FROM AUTHOR]

• Fly ash from a coal gasification plant was used for the synthesis of zeolite X. • Only zeolite X showed CO 2 adsorption capacity among different synthesis products. • The effect of three parameters was studied to improve the CO 2 adsorption capacity. • NaOH/CFA ratio 1.4, crystallization at 80 °C for 7 h yielded best adsorption result. The coal fly ash (CFA) from a coal gasification plant was used as raw materials for X zeolites synthesis by fusion and hydrothermal method and the ability of CFA-derived zeolites to adsorb CO 2 was studied. After characterization of CFA, factors affecting the synthesis of different zeolites from this CFA, i.e., NaOH/CFA weight ratio, crystallization temperature and crystallization time were investigated. X-ray powder diffraction showed that only the experimental conditions corresponding to 1.2 NaOH/CFA, 7 h and 90 °C have led to a mixture composed by NaX and amorphous compounds without the formation of other crystalline structures. This product has a specific surface area of 498 ± 4 m2/g and exhibits a CO 2 adsorption capacity of 2.18 molCO 2 /kg, corresponding to 57% of commercial 13X. Results showed that this feature is directly related to this specific crystalline product and not to other zeolitic forms or to amorphous phases. The design of experiment, named central composite full factorial, was accounted to optimize these synthesis parameters in order to maximize the CO 2 adsorption capacity of the CFA-derived zeolites. Thermogravimetry experiments showed that the experimental setting corresponding to 1.4 NaOH/CFA, 80 °C and 7 h has led to a material with an adsorption capacity of 3.3 molCO 2 /kg, the 86% of commercial 13X. Furthermore, results highlighted that all the examined synthesis parameter are significant for the purpose of improving CO 2 adsorption capacity of CFA-derived zeolites but too high values entail the production of more stable and useless (for this purpose) zeolites. [ABSTRACT FROM AUTHOR]