Biochar for gas sensors devices

In recent years, biochar applications are present in many fields [1]. It has been studied as substitution for more expensive carbon materials like carbon nanotubes, graphene and others. The evident advantage for biochar is its low cost of production, being an environmentally friendly source of huge carbon content. On the other hand, nowadays the main application of this material is as field amendment in agriculture [2]. Starting for the peculiarity of biochar, it is possible to modify its features. For instance, after high temperature treatments, its surface area can increase sharply. Please click on the file below for full content of the abstract

Deterioration of dolostone by magnesium sulphate salt: an example of incompatible building materials at Bonaval Monastery, Spain

Since its abandonment 185 years ago, the XII century Santa Maria de Bonaval Monastery located in Guadalajara (Spain) has suffered significant deterioration: first the roof was lost, followed by partial collapse of the walls, moisture infiltration and extensive loss of stone surfaces due to salt weathering. This case study is a clear example of the incompatibility of some building materials: in this case, the combination of sulphate-bearing mortars and magnesium-rich stone and mortars leading to extensive weathering by magnesium sulphate crystallization. Samples of plaster, bedding and core mortars, stone fragments and flakes, salt crust and powders were collected, as well stone samples from the historic quarries located close to the Monastery. Characterization by XRD (X-ray diffraction), ESEM-EDS (environmental scanning electron microscopy with energy dispersive X-ray spectroscopy) shows that the most important stone-type used in the structure, dolostone, is mainly affected by magnesium sulphate salts (epsomite, MgSO4 · 7H2O), although other salts as kalicinite (KHCO3) and mercallite (KHSO4) were also detected. The connected porosity and pore size distribution determined by mercury intrusion porosimetry and capillarity behaviour suggest that the core mortar could easily be dissolved and the stone, plaster and bedding mortars are able to transport infiltrating solutions, giving rise to the precipitation of magnesium sulphate in the mortar joints and over the surface of the stone. Due to their chemical incompatibility, the combination of sulphate and magnesium-bearing mortars and stone with high magnesium content appears to be problematic and should be avoided in future restoration work.Ministry of Science and Technology JCCM, Toledo (Spain) and the European Social Fund; Spanish projects C.I.C.Y.T.-CGL2004-03564/BTE and MATERNAS-S-0505/MAT/000094

Elaboration and characterization of novel humidity sensor based on micro-carbonized bamboo particles

In this work, eco-friendly, low cost and efficient humidity sensors were prepared from micro-sized pyrolyzed bamboo. Two types of pyrolyzed particles were investigated: as such carbonized bamboo (CB) and annealed ones (CBA). After pyrolysis, the materials were first manually ground and then, attrition milled. The synthesized particles were characterized by using field emission-scanning electron microscopy (FESEM), Raman spectroscopy, specific surface area (SSA) measurements and thermogravimetric analysis (TGA). The sensing materials were screen-printed onto commercial α-alumina substrates with platinum electrodes prior to firing at 300°C for 1 h. The humidity sensing characteristics of the pyrolyzed bamboo based sensors were investigated at room temperature in the relative humidity (RH) range from 0.0 to 96.0%. The pyrolyzed bamboo based humidity sensors exhibited an excellent response towards humidity starting from 10% RH, while CBA showed a response starting from 20% RH. Finally, the response and recovery times were reasonably fast (less than 2 min)