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In this work, the chromium-based MIL-101 metal organic framework has been synthesized and investigated as a fully regenerable, high capacity sorbent for siloxanes, which are common contaminants in raw biogas from anaerobic digestion. Adsorption isotherms of D4, the most common siloxane in waste treatment plants, have been collected at different temperatures and modelled by means of the Langmuir theoretical isotherm. The selected metal organic framework shows a remarkable affinity for siloxane adsorption and an outstanding saturation capacity weakly dependent on temperature. Moreover, repeated adsorption isotherms, collected after a reactivation treatment of the same adsorbent sample, clearly indicate full regeneration capabilities. Considering that chromium-based MIL-101 is also a noticeable H2S adsorbent, the results reported in this work pave the way to its potential application for the simultaneous removal of the two main poisoning compounds contained in biogas.

An innovative and facile synthesis of cobalt based inorganic pigment was carried out by means of a low energy thermal conversion of a cobalt-exchanged zeolite. The Na-A [LTA] zeolite was used, since it is a low cost and easily available raw material. The ion exchange mechanism allowed to control, at microscopic level, the composition of the zeolitic precursor. Several chromatic effects could be obtained by varying the treatment temperature and/or the cobalt concentration in the contact solution. The reliability of these new zeolite-based pigments was tested in porcelain manufacture, in collaboration with the Institute for the Capodimonte porcelain “Giovanni Caselli”. The developed cobalt pigments were successfully tested either in the porcelain mixture to obtain a coloured product or in the decoration step (such as ingobbio, colored glazes and “third fire decoration”).

The paper represents the “state of the art” on sustainability in construction materials. In Part 1 of the paper, issues related to production, microstructures, chemical nature, engineering properties, and durability of mixtures based on binders alternative to Portland cement were presented. This second part of the paper concerns the use of traditional and innovative Portland-free lime-based mortars in the conservation of cultural heritage, and the recycling and management of wastes to reduce consumption of natural resources in the production of construction materials. The latter is one of the main concerns in terms of sustainability since nowadays more than 75% of wastes are disposed of in landfills.

The requirement for environmentally friendly construction materials for sustainable development is nowadays an important issue and the geopolymer technology provides a good solution to replace, as binder, the ordinary cement materials for green building. Fly ash, an industrial by-product currently disposed of as waste, can be used as feedstock for geopolymers with an excellent greenness. In order to preserve the eco-friendly nature of the fly ash based geopolymer and enhance the mechanical properties that represent a weak point of the cementitious materials, limiting their application fields, a new fly ash based geopolymer composite was introduced. For this purpose, inorganic, organic and natural short fibers, i.e. E-glass, aramid and hemp respectively, were considered as reinforcement. The mechanical response of these composites under quasi-static and dynamic load conditions was investigated and compared to plain geopolymers, drawing the attention to the hemp reinforced ones, because of their low coast and eco-friendly nature.

This review presents “a state of the art” report on sustainability in construction materials. The authors propose different solutions to make the concrete industry more environmentally friendly in order to reduce greenhouse gases emissions and consumption of non-renewable resources. Part 1—the present paper—focuses on the use of binders alternative to Portland cement, including sulfoaluminate cements, alkali-activated materials, and geopolymers. Part 2 will be dedicated to traditional Portland-free binders and waste management and recycling in mortar and concrete production.

In this work, the potentialities of the amino-functionalized, chromium-based MIL-101 metal organic framework (NH2-MIL-101) as a high capacity, fully regenerable hydrogen chloride adsorbent have been proved by a thorough adsorption thermodynamics investigation. The chosen adsorbent showed high gaseous HCl adsorption capacities and, to the best of our knowledge, it is the first example of a totally regenerable substrate for this kind of adsorbate, as evidenced by both experimental and modeling results. This paves the way to the implementation of greener, more energetically efficient pressure/temperature swing adsorption processes to purify biogas feeds for high-temperature fuel cells.

The galeb of Kebili is a sun-dried brick belonging to the construction tradition of the homonymous “oasis city” of southern Tunisia, obtained by mixing water, fired gypsum-rich Sahara sand and palm wood ash. In recent years, great efforts have been made to enhance the features of these construction materials while preserving the traditional production techniques. In order to evaluate possible improvements in the brick’s physical and mechanical properties, both different firing techniques of raw materials and various ash content in the composition, have been considered. Experimental results showed that modifying the traditional method of combustion by firing the sand at a controlled temperature (160 °C) in a standard oven, allows to obtain a galeb brick with improved mechanical and physical properties. Moreover, keeping the traditional method of combustion, mechanical and physical properties may be optimized by adding a controlled amount of raw ash (about 5 %) in the galeb bricks composition.

The microstructure evolution of lime putty upon aging was investigated by slaking quicklime (CaO) with an excess of water for 3, 12, 24, 36, 48 and 66 months. The as-obtained lime putties were characterized in the water retention and in the particle size distribution using the static laser scattering (SLS). The same lime putties, dehydrated by lyophilization, were also investigated in the pore size distribution by mercury intrusion porosimetry, in the surface area by the BET method and, finally, in particle morphology by scanning electron microscopy (SEM). The effect of the extended exposure of quicklime to water confirms a shape change from prismatic crystals of portlandite, Ca(OH)(2), into platelike ones. Simultaneously a growth of larger hexagonal crystals at the expense of the smallest ones (Ostwald ripening) favours a secondary precipitation of submicrometer platelike crystals of portlandite. The shape change and the broader particles size distribution of portlandite crystals upon aging seem to contribute to a better plasticity of lime putty. (C) 2010 Elsevier B.V. All rights reserved.

The capillary rise of water in porous stones of masonries can be stopped by interleaving appropriate cement-lime mortars between the building stones. The type of cement in the mortar influences the time requested for the formation of an impermeable lime layer, responsible of the phenomena.

The sintering of zircon-based (ZrSiO 4 ) ceramics prepared from a batch containing ball clay and wollastonite as additives has been studied. Physical properties of extruded and dry pressed specimens fired at 1280 °C are compared with those of extruded test specimens of pure zircon fired at 1600 °C. The sintering aids of zircon determine the formation of a glassy phase in which the zircon is embedded. The partial crystallization of such a glassy phase, performed with a nucleation and crystal growth process, enhances the strength of the fired zircon-based bodies. These materials have been utilized as a grinding medium for industrial frits and glazes.

Aluminosilicate refractory bricks exposed for a long period to the action of heavy oil combustion products were analysed. The bricks located in zones characterized by higher working temperatures are mainly degraded by Na 2 O and V 2 O 5 , while SO 3 represents the most important contaminant at lower working temperatures. Two series of different mixtures were prepared, taking into account the significant increase in the contaminant contents of the refractory bricks exposed to fuel oil products. V 2 O 5 , Na 2 O and SO 3 were added to as-received aluminosilicate refractory and to a mullite-cristobalite mixture. These mixtures, in pelletized form, were thermally treated at temperatures ranging between 600 and 1300°C. The results enable the differences between the data obtained in laboratory and those observed in refractory bricks employed in combustion chambers to be explained. In this last case, in fact, preferential contact between impurities and refractory material may be expected in microzones of the brick characterized by the presence of cracks and pores in which the fuel oil impurities might concentrate.