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Conservation and restoration of heritage structures represents a highlighted issue, the main challenge being to bring the cultural objective to its original state, or as close as possible to it by using eco-friendly materials with lover impact on the environment and human health. Within this study, the calcium zincate nanoparticles have been synthesized starting from the eggshels wastes through the precipitation method. For this purpose, the raw eggshells were washed for organic traces removal and disolved in concentrated HCl solution to form CaCl2. The Ca(Zn(OH)3)2•2H2O was obtained by adding into the chemical reaction media a solution of zinc acetate dihydrate previously dissolved in 100mL of methanol under vigorous stirring at room temperature and precipitating with NaOH 12M solution. The white precipitate was characterized by field emmision scanning electron microscope (SEM), X-Ray diffraction (XRD) and thermal analyses (DTA-TG). The Scherrer equation result showed the nanometric size of calcium zincate crystallite, about 23nm. [ABSTRACT FROM AUTHOR]

The work relates to a composition of an additive mortar with a volumetric weight below 250kg/mc, the thermal conductivity coefficient below 0,08kcal/m×h×°C, mechanical strengths more than 7daN/cm² with self-cleaning effect after commissioning. In order to obtain a selfcleaning effect over time by eliminating chromatic deviations, the composition of ZnO, TiO2 and the three colored ceramics mixture is reformulated by optimizing the content based on color adjustment, by using a specialized software and CIE L*a*b* colorimetry for pressed bulk powders, at the medium one given by the patina. The composition optimization is performed by modifying, as appropriate, the addition rate of eggshell powder by a reformulated percentage related to the three fine colored ceramic powders. The freshly prepared mortar is applied to the restoration of the historical monument's facades through physical-structural and chromatic reintegration interventions. Depending on the conservation state of the apparent structures, two stages with differentiated specific operations are used: for surfaces without gaps, but chromatically degraded and with deposits of embedded dirt, it is spread with a trowel in the form of thin plasters on fiberglass mesh and in case of damage with deep lacunars areas the consolidation of the mobile structures will be first executed and grouting with a simple mortar based on river sand, expanded perlite, Portland cement and water in gravimetric ratio sand:perlite:cement:water = 2:1:2:5. After strengthen the same thin plasters will be applied on the fiberglass mesh. The new mortar allows the accomplishing of a series of advantages both in the processes of paste obtaining, as well as during commissioning and after, respectively within the period of integration in the tourist circuit. [ABSTRACT FROM AUTHOR]

The heritage conservation always remains a scientific and complex task. Either used for preservation of cellulose-based artifacts or as limestone consolidant, the nano-Ca(OH)2 is often associated with its carbonation process. The use of waste materials for nano-Ca(OH)2 synthesis transforms the entire process into a handy and sustainable one. Within this study, the calcium hydroxide nanoparticles have been synthesized from eggshell wastes through the precipitation method. For this purpose the raw eggshells were washed for organic traces removal and disolved in concentrated HCl solution to form CaCl2. The nano-Ca(OH)2 was obtained by adding into the chemical reaction media a solution of NaOH, the white precipitate being afterwards dried at 100°C for two hours. The synthesized nanoparticles were characterized by X-Ray fluorescence (XRF), scanning electron microscope (SEM), XRay diffraction (XRD), thermal analyses (DTA-TG) and laser granulometry using as comparative specimen a commercial calcium hydroxide. The granulometer analyses showed that the particle size of the obtained nano-Ca(OH)2 was in the range 10 - 150nm, these results being also confirmed by SEM images. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Industrialization on a global scale has led to water pollution with a variety of persistent organic pollutants, highly toxic and hazardous to the living organisms and also difficult to remove with the existing wastewater treatment technologies. Various methods have been tested for removing these organic contaminants, among which nanotechnology appears to be one of the most promising approaches, as nanomaterials present larger specific surface area and particular physical, chemical and biological properties (developed due to small particle size) suitable for environmental applications. In recent years, SiO2, TiO2 and ZnO nanoparticles have been the focus of interest in the wastewater treatment investigations. In the present paper, ZnO nanoparticles were synthesized through the hydrothermal method. The concentration of the alkaline solution was varied in order to obtain ZnO nanoparticles with a high crystallinity degree. The obtained nanoparticles were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results showed that the concentration of the alkaline solution influences the size and shape of the particles [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)