Synthetic calcium carbonate improves the effectiveness of treatments with nanolime to contrast decay in highly porous limestone

Abstract

Three synthetized polymorphs of calcium carbonate have been tested in combination with the suspension of nanolime particles as potential consolidating agents for contrasting stone decay and overcome some of the limitations of nanolime agents when applied to substrates with large porosity. The modifications induced in the pore network of the Maastricht limestone were analyzed with microscopy and in a non-invasive fashion with small angle neutron scattering and synchrotron radiation micro-computed tomography. A reduction in porosity and pore accessibility at the micrometric scale was detected with the latter technique, and ascribed to the improved pore-filling capacity of the consolidation agent containing CaCO3 particles. These were found to be effectively bound to the carbonated nanolime, strengthening the pore-matrix microstructure. Penetration depth and positive effect on porosity were found to depend on the particle size and shape. Absence of significant changes in the fractal nature of the pore surface at the nanoscale, was interpreted as indication of the negligible contribution of nanolime-based materials in the consolidation of stones with large porosity. However, the results indicate that in such cases, their effectiveness may be enhanced when used in combination with CaCO3 particles, owing to the synergic effect of chemical/structural compatibility and particle size distribution.

Electrochemical Capture and Storage of CO2 as Calcium Carbonate

“…Figure 2b shows an SEM image of SrCO 3 , which demonstrates a flower‐like microstructure where the elongated needle like structures show a highly textured surface, which is consistent with previous observations on the morphology of this material, [29] whereas EDS analysis confirmed that Sr, C, and O are present (Figure 2e). In the case of CaCO 3 , coalesced cubic crystals with a smooth texture was observed (Figure 2c), which is highly indicative of calcite formation, [30] whereas EDS analysis confirmed the presence of Ca, C, and O (Figure 2f). MnCO 3 was found to crystallize in a spherical shape of different sizes, which exhibited a highly textured surface (Figure 2d), consistent with a previous report, [31] and EDS analysis confirmed the presence of Mn, C, and O.…”

Efficient Carbon Capture and Mineralization Using Porous Liquids Comprising Hollow Nanoparticles and Enzymes Dispersed in Fatty Acid-Based Ionic Liquids

“…A definitive assessment of the morphology of CaCO 3 crystals was performed using SEM, infrared spectroscopy, and PXRD analysis. Figure a–c shows representative SEM images of CaCO 3 extracted from [CA–MA–PLs]; a combination of different crystal structures of various shapes including pseudocubical, rod-like, and spherical structures were seen, much in resemblance to CaCO 3 crystals reported in the literature. − Figure a shows that cubic calcite crystals of sizes 2.5 × 2.7 μm were observed, while in another area within the same sample, different sizes of aragonite rod-like crystals with an average size of 7.6 × 2.2 μm were seen (Figure b); vaterite was also observed in certain regions with an average size of 11 ± 3 μm (Figure c) (average sizes have been provided in the Supporting Information, Figure S19). XRD analysis (Figure d) showed peaks of calcite crystals at 2θ = 23, 29, 31,39, 44, 46, 48, 56, 60, and 65° corresponding to (012), (104), (110), (113), (202), (024), (211), and (214) planes, respectively (PDF#05–0586) .…”

Advanced mapping of inorganic treatments on porous carbonate stones by combined synchrotron radiation high lateral μXRPD and μXRF

“…This technique, when complemented with the elemental information of micro-X-ray fluorescence (μXRF) mapping, becomes particularly well-suited for the micro-analysis of highly heterogeneous systems, especially when the new phases are present in minor fractions if compared to the substrate’s minerals or are poorly crystalline. These techniques, although well-known and already used in many fields over the years 31 – 35 , in CH materials are mainly used in the examination of oil paintings 22 – 39 and wall paintings 40 , 41 , ceramics 42 , 44 , paper 45 , and metals 46 , 47 , but, to the best of our knowledge, have not been employed to study the reaction products of inorganic consolidation solutions on porous carbonate stones in CH.…”