Calcium Carbonate CaCO3 Research Articles

Analysis of the settling process to improve the quality of phosphate products of the Djebel Onk deposit

The object of the study is the phosphates of the Djebel Onk region, which are part of a vast group of phosphate deposits formed in the Late Cretaceous-Eocene period on the South and Southeast Mediterranean shores. These concentrations of economic interest are operated near the town of Bir El Ater (Tebessa, Algeria). The mining industry based on the extraction and processing of different minerals while respecting the environmental framework plays an important role in the economy of a country. The economic potential of each country will be determined based on the level of production of metals and various mineral substances. In the case of the Djebel Onk phosphate ore, the most dominant mineral in addition to P2O5 is calcium carbonate CaCO3 with more than 50 % in the all-mineral content. In addition, phosphate concentrate contains harmful elements which reduce the value of the market product. Therefore, this study aims to recover the enriched product efficiently and profitably with a minimum of deleterious elements. This work aims to develop a treatment technology with a minimum rejection rate, which allows for achieving production goals and reducing environmental impacts. For this purpose, we proposed an enrichment of these phosphate discharges from the settling process utilizing pneumatic selection (Turbo Separator Ventilate – TSV). The results of the chemical analyses confirm the significant difference in useful and major elements (P2O5) and the minor and harmful elements (MgO). According to the granulochemical analysis of each slice, it is possible to note that the P2O5 content is similar to the various particle-size slices. It is therefore necessary to treat the mass of waste if we want to recover as much phosphate as possible. The obtained X-ray diffractograms highlighted appreciable differences between the raw phosphates and the concentrates, in fact, the qualitative and quantitative variation of the mineralogical species, particularly the calcite, quartz, dolomite, and apatite. TSV is a process used to improve the quality and quantity of phosphate and to eliminate the layer below 0.8 mm. Corresponding to the analyses it was appeared that the P2O5 content 29.5–30 % of the settled product increases to 30.2–31 % after dust removal. Then it is possible to achieve an increase in the quality of phosphate from 63/65 % TPL to 66/68 % TPL.

Application of calcium carbonate (CaCo3) at different time intervals on the growth of freshwater lobster (Cherax quadricarinatus)

Freshwater lobsters are one of the crustacean commodities that have started to be developed through cultivation. Besides having high nutritional value, freshwater lobsters have a stable sales value or price throughout the year. Freshwater lobster is a crustacean commodity that is not easily stressed or easily attacked by disease. The availability of calcium is essential for lobster growth, especially the formation of its shell. This research aims to determine the effectiveness of adding calcium carbonate at different time intervals by adding 150 mg/L CaCO3 lime. The study was conducted from June to July 2020 at the Aquaculture Environmental Laboratory, Bogor Agricultural Institute. The research used a Completely Randomized Design (CRD) with five treatments and three replications. The treatment used was K+ and K-, and the time interval for adding CaCO3 was once every five days, once every ten days, and once every 15 days. The aquarium measures 100 x 50 x 51 cm with a water height of 21 cm. The lobster used measures 1.5 cm. The research results after statistical testing showed that aquarium A1 (addition of CaCO3 every five days) experienced an increase in length of 0.67 cm. Weight of 0.67 g, B1 (addition of CaCO3 every ten days) experienced an increase in length of 0.87 cm and weight of 0.78 g, C1 (addition of CaCO3 every 15 days) experienced an increase in length of 0.97 cm and weight of 0.98 g, K+1 experienced an increase in length of 1.05 cm and weight of 1.06 gr, K-1 experienced an increase in length of 0.46 cm and weight of 0.45 g.

ТЕХНОЛОГИЯ ЗАМКНУТОГО ЦИКЛА ПОЛУЧЕНИЯ СТРОИТЕЛЬНОГО ГИПСА ИЗ ОТХОДА ЭНЕРГЕТИКИ И ДЫМОВЫХ ГАЗОВ ТЕПЛОВОЙ ЭЛЕКТРОСТАНЦИИ

A closed-cycle technology for building gypsum producing using energy waste and flue gases of thermal power plants has been developed. The technology is based on an absorption method for purifying gas emissions from industrial enterprises from sulfur dioxide SO2 using a suspension of carbonate sludge and obtaining a finished product – gypsum dihydrate. The commercial gypsum is obtained by using a suspension of carbonate sludge as a reagent. The suspension is formed at the stage of preliminary purification of natural water during coagulation and liming. Coagulation is carried out with ferrous sulfate heptate FeSO4×7H2O, liming – with a saturated solution of lime milk Ca(OH)2. As a result of combining the two processes, a suspension of a certain chemical composition is formed. The chemical composition of the sludge and its technological characteristics are presented. The main substance in the chemical composition is calcium carbonate CaCO3, which allows using a sludge suspension in the chemical reaction of the interaction of flue gases from thermal power plants with the formation of building gypsum. An absorber with a fluidized nozzle has been selected and designed to purify gas emissions from wet suspensions and produce commercial dihydrate gypsum. Hollow or solid hydrophobic polyethylene balls were selected as nozzles to reduce the adhesion of sludge suspension particles to their surface. A technological scheme is presented for purifying flue gases from sulfur dioxide to obtain the finished product – building gypsum. The scheme includes the proposed adsorber, sludge suspension tank, hydrocyclone and filter press. The cost of the resulting commercial building gypsum was calculated, which amounted to 15 rub./year, the payback period was 3,5 years. The prevented environmental harm from soil and land degradation from the introduction of this technology at thermal power plants was calculated by reducing the emission of sulfur dioxide into the air, which amounted to about 1 mil. rub./year.

Kinetics of zinc leaching from intermediate feedstocks

The aim of the work was to study the leaching kinetics of zinc from the compound CaO. ZnO, formed during the sintering of dust from electric arc furnaces with limestone, as well as to identify the mechanisms by means which such chemical interactions occur. The object of the study was the dust sinter of electric arc furnaces with limestone obtained at the Chelyabinsk Zinc Plant. It was found that zinc is contained in sinter in the form of readily soluble CaO. ZnO. The elemental composition of the initial dusts and sinter was determined by the spectral atomic emission method using inductively coupled plasma on a Spectroblue optical emission device and spark spectrometry. The phase composition of the materials was studied on a Bruker D8 Advance X-ray diffractometer. The initial sinter was milled to apowder state having a particle size of ~0.04 mm and with a yield of ~97% of the composition, %: 11.9 Zn; 28.5 Ca; 16.6 Fe; 0.38 Mg; 0.14 Pb; 0.05 Cl. Experiments on the leaching of Zn with NaOH solution were carried out at the following parameters: the initial concentration of zinc in the pulp was 0.202 g-ion/dm3 ; alkali concentration – 5‒9 mol/dm3 NaOH; L:S = 9:1; pulp mixing rate – 10‒20 rad. c-1; temperature – 333‒363 K; duration – 0.5–2.5 hours. It has been shown that zinc from sinter passes into solution as sodium tetrahydroxozincate Na2[Zn(OH)4], while calcium remains in the cake, mainly as insoluble Ca(OH)2, which reacts with carbon dioxide to form insoluble calcium carbonate CaCO3. The process of dissolving zinc from the sinter corresponds to the external diffusion mode of mutual transfer of the initial reagents and reaction products through the surface layer of the liquid at the interface of the “liquid–solid” phases with an activation energy value equal to 12.44 kJ/mol. Thus, with the studied parameters of zinc leaching with NaOH solution, the process proceeds in an external diffusion mode. The results are of interest when identifying conditions corresponding to the intradiffusion and kinetic modes of zinc leaching.

Structural performance of self-healing concrete by Bacillus bacteria with addition of rice husk ash

The spores of the bacillus bacteria release calcium carbonate (CaCo3) that fill-up the microcracks in the concrete, that is to say that this biological agent added in the concrete instead of deteriorating the material works as a self-healing agent, several investigations have studied the influence of this bacillus bacteria in the concrete mainly in the species baccilus genus showing its benefits for the concrete with respect to its increase of resistance in the concrete. On the other hand, a replacement for the cementitious material has also been studied, finding that rice husk ash (RHA) in a proportion of 10% not only works as a replacement but also contributes to an increase in the strength of the concrete. In the present work, the mechanical properties of fresh and hardened concrete were investigated with a 10% replacement of RHA and four concentrations of bacillus subtilus bacteria. The study presents the use of bacillus subtilus specie and its behaviour with the addition of rice husk ash. The results showed an increase in compressive strength of up to 25,83% compared to conventional concrete and 44.80% compared to concrete with RHA addition. This research aims to promote the use of bacteria in concrete, as they not only provide an increase in compressive strength but also enhance the concrete's service life by endowing it with self-healing capabilities.

Flue Gas Desulfurization Scrubbers in Heavy Diesel Combustion Plants

Through the purification technology of flue gas desulfurization, ultralow emissions of SO2 flue gas in industrial flue gas can be achieved. In this article, wet flue gas desulphurization (FGD) processes using limestone (calcium carbonate CaCO3) and caustic (sodium hydroxide NaOH) as absorption solution are introduced in terms of fluid mechanics and mass transfer phenomena as well as absorption unit processes. Also initial investment and operation costs are compared for wet flue gas desulphurization processes using limestone and and caustic.

RADIOCARBON STEP-COMBUSTION OXIDATION METHOD AND FTIR ANALYSIS OF TRONDHEIM CaCO3 PRECIPITATES OF ATMOSPHERIC CO2 SAMPLES: FURTHER INVESTIGATIONS AND INSIGHTS

ABSTRACT Eight atmospheric carbon dioxide samples (as calcium carbonate—CaCO3—precipitates) from Lindesnes site (58ºN, 7ºE), belonging to 1963 and 1980 (four samples from each year) and stored at the National Laboratory for Age Determination (NTNU), have been reevaluated through radiocarbon (14C) analysis. Previous 14C results indicated the presence of a contaminant, which was not removed through different chemical cleansing procedures (e.g., hydrochloric acid—HCl and/or hydrogen peroxide—H2O2). Here, we present a follow up investigation using 14C step-combustion and Fourier-transform infrared spectroscopy (FTIR) analysis. Results from 14C data indicate unsuccessful removal of the contaminant, while further FTIR analysis displayed the presence of moisture. This finding alludes to the possibility that the contaminant is of ambient air-CO2 deeply embedded in CaCO3 powders (within clogged CaCO3 pores and/or bonded to the lattice). Samples were found exposed to air-CO2 and humidity. These conditions may have lasted for years, possibly even decades, leading to the 14C offsets detected here.

Behavior of Calcium Compounds under Hydrothermal Conditions during Alkaline Leaching of Aluminosilicates with the Synthesis of Fillers for Composites

Calcium oxide plays an important role in alumina production by binding SiO2 from aluminosilicate raw materials (bauxite, nepheline, kaolinite, etc.) in aluminum-free compounds. The efficiency of the hydrochemical technology depends on the activities of calcium oxide or its compounds introduced into the alkaline aluminosilicate slurry. In this paper, we considered the effects of different calcium compounds (calcium carbonate CaCO3, gypsum CaSO4·H2O, calcium oxide CaO and calcium hydroxide Ca(OH)2), introduced during the hydrothermal stripping of aluminosilicates with alkaline solutions, on the degree of aluminum oxide extraction, with the subsequent production of fillers for composites. Ca(OH)2 was obtained by the CaO quenching method. Extraction of Al2O3 in an alkaline solution was only possible with Ca(OH)2, and the degree of extraction depended on the conditions used for CaO quenching. The effects of temperature and of the duration of CaO quenching on particle size were investigated. In potassium solution, the best results for Al2O3 extraction were obtained using CaSO4·H2O gypsum. The obtained solutions were processed using the crystallization method.

Impacts of Different Sources of Carbonates on Growth of <i>Fusarium oxysporum</i> f. sp. <i>lycopersici</i> in Different Growth Media

<em>Fusarium</em> <em>oxysporum</em> f. sp. <em>lycopersici</em> (FOL) is the most common soil-borne pathogen that causes wilt in many plant crops, among which the tomato is one of the most susceptible crops. This experiment is conducted to analyse the impacts of inorganic carbon compounds i.e., calcium carbonate CaCO<sub>3</sub>, sodium carbonate Na<sub>2</sub>CO<sub>3</sub> and potassium bicarbonate KHCO<sub>3</sub> on the growth of FOL causing wilt in tomato plant in different culture media including Malt Extract Agar (MEA), Potato Dextrose Agar (PDA) and V8. Three concentrations viz 0.5 g/L, 1 g/L and 1.5 g/L of each carbonate are applied. The study indicates that the efficiency of carbon compounds is related to the nature of the media. Among various carbon compounds tested in the present study, maximum growth is obtained with KHCO<sub>3</sub> while FOL showed least growth with Na<sub>2</sub>CO<sub>3</sub> in each of the three media. MEA has more profound effect on limiting the growth and biomass of the fungus than compared to V8 and PDA. This shows <em>Fusarium</em> growth is restricted in the chemical environment containing Na<sub>2</sub>CO<sub>3</sub> and MEA. In addition, the study reflects that <em>Fusarium</em> thrives well in PDA containing KHCO<sub>3</sub> in each of its three concentrations which may be involved in vegetative and reproductive growth. This study paves a path for further research on how the growth behavior of FOL can be controlled under the influence of inorganic carbon compounds in the soil and yet in the face of environmental changes.

Optimizing the addition of calcium carbonate (CaCo3) on the growth and survival of glass eel (Anguilla sp.)

The development of eel fish cultivation has quite good business opportunities and prospects. However, the main obstacle in cultivating eel fish is the high mortality in the glass eel phase, so it has a survival rate of 30-50% and slow growth, namely less than 3.1%. One effort to maximize glass eel maintenance is through optimizing alkalinity as a buffer for water quality. The alkalinity level in the maintenance medium can be regulated by adding calcium carbonate (CaCO3). This research aims to determine the effect of adding CaCO3 to the rearing media on glass eels' growth and survival rate. The study was conducted for 14 days in March 2023. The method was wholly randomized with three replications in 3 treatments (P1=0 mg L-1, P2=50 mg L-1, P3=100 mg L-1). Analysis of research data used the ANOVA test. Adding CaCO3 produced a natural effect on length growth with a value of 0.16 cm, weight growth of 0.73 mg L-1, and a survival rate of 74%. The treatment did not naturally affect the alkalinity levels in the glass eel maintenance media. The best treatment effect was found in P2 (50 mg L-1). These results show that adding CaCO3 to the glass eel-rearing media decreased but did not naturally affect alkalinity levels.

Diagnosis of two local mushroom species (Pleurotus spp.) and their production management

The present study confirmed the identity of two Iraqi mushrooms by using the internal transcribed spacer (ITS) sequence; the genomic DNA of two isolates was amplified using ITS1 and ITS4 primers, and the data analyzed through Basic Local Alignment Tool( BLAST) search was achieved using the National Center for Biotechnology Information (NCBI) database. The result shows that the nucleotide sequence of two mushrooms blasted against the sequence from the Gene Bank database that Pleurotus ostreatus and Pleurotus eryngii matched 99% and 100%, respectively. The second stage of the current study was the comparison of different agro-waste, including wheat straw(WS), corncob(CC) and sawdust(SD) supplemented with 25% wheat bran(W) and 2% calcium carbonate (CaCo3) on mycelium growth, yield and biological efficiency (BE) of local oyster mushroom which comparison with Chinese strain pleurotus ostreatus121 and pleurotus eryngii 080. The highest growth average of local P. ostretus on the SD substrate was 1.50 cm, and P.eryngii was recorded at 1.18 cm. The substrate CC was the most suitable for the yield of mushroom local P. ostreatus and P. ostreatus121(485.40 and 418.50 g/bag, respectively), while local P. eryngii recorded 470.40 in the same substrate. It was also found that the WS substrate recorded the highest BE for each local isolate and Chinese strain. Keywords: Iraqi strains, Pleurotus spp., agricultural wastes, wild agricultural mushrooms

Fourier Transform Mid-Infrared Spectroscopy (FT-MIR) as a Method of Identifying Contaminants in Sugar Beet Production Process-Case Studies.

Food safety has received considerable attention in recent years. Methods for rapid identification of a variety contaminants in both the final product and the manufacturing process are constantly developing. This study used Fourier Transform Mid-Infrared Spectroscopy (FT-MIR) spectroscopy to identify various contaminants endangering white sugar production. It was demonstrated that inorganic compounds (calcium carbonate-CaCO3), plastic contaminants (polypropylene), and oily contaminants (compressor sealing and lubrication lubricant) can be identified with a high degree of precision. FT-MIR spectroscopy was proved to be a useful technique for detecting sugar contaminants rapidly and precisely even without the application of a sophisticated spectra analysis. Commercial databases of reference spectra usage significantly simplify and facilitate the application of this method.

Eco-friendly belite cement elaborated from shell and glass powder

The purpose of this study is to use inorganic wastes to completely replace traditional raw materials for the production of belite rich clinkers, waste glass as a source of SiO2 oxide and shells as a source of calcium carbonate CaCO3 to synthesize belite-rich cement. After grinding, the raw materials were blended to synthesize the dicalcium silicate phase (Ca2SiO4) in a heat treatment up to 1000 °C. The clinkers produced were rich in elaborated Ca2SiO4, mixed with gypsum and shell powder as a source of calcium carbonate to form belitic cements. The cements were prepared and hydrated with different proportions of belitic clinker (56, 62 and 72%).The specimens were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The results of the XRD and FTIR analyses demonstrate that hydration of the three cements over time leads to the formation of crystallized C-S-H compounds, which increase in abundance after 90 days upon the increase of the C2S percentage. We have attempted here to provide an update on the development of high-belite cements with low CO2 emissions.

Characteristics of ceramic-like coatings obtained by plasma electrolyte oxidation on different Ti alloys

Plasma electrolyte oxidation was used to modify the surface of different Ti alloys: c.p. Ti (α hcp structure), Ti–15Nb (α′+β structure) and Ti–33Nb–33Zr (stable β cubic structure) and the influence of elements and microstructure in the TiO2-based ceramic layer formed as well as the surface properties was analyzed. The XRD patterns confirmed the presence of TiO2 (anatase and rutile) in the c.p. Ti. For Ti–15Nb (wt.%) indicated the presence the same oxides also of pentoxide niobium (Nb2O5). For Ti–33Nb–33Zr (wt.%) indicated just the presence of rutile as the stable oxide one at room temperature and dioxide zirconium (ZrO2). In addition, the formation of calcium carbonate CaCO3 and calcium phosphate Ca3(PO4)2 was detected in all 3 materials. The ceramic-like layer was more homogeneous for c.p. Ti and Ti–15Nb and more irregular hole like-pores for Ti–33Nb–33Zr. Bioactive ions used were detected in all alloys and the roughness for Ti–15Nb was higher compared to c.p. Ti. and Ti–33Nb–33Zr. The contact angle for the three samples was higher than 100°.

Modeling effective elastic and thermal conductivity of composite materials reinforced with plastic waste: Analytical and numerical approaches

AbstractThe properties of materials used in building are enhanced by adding nanoparticles for improve energy efficiency. The objective of this study is to offer both numerical and analytical modeling methods of the thermal conductivity and mechanical property of composite materials. Various mineral charges were employed to reinforce the organic matrices of saturated polyester resin (UPR) with calcium carbonate (CaCo3) and expanded perlite particles. The study employs the finite‐element software COMSOL to conduct a numerical investigation of thermal transport in an elementary cell. The purpose is to ascertain the thermal conductivity of composites and examine the impact of contact resistance and the volume fraction of nanoparticles on the effective thermal conductivity. The results indicate that the numerical model proposed is consistent with the Hashin‐Shtrikman analytical model and experimental measurements. In another hand, the mechanical property is computed based on Mori‐tanaka analytical model of homogenization and finite element method by Digimat‐MF/FE, which gives enhanced elastic behavior of composite in function of volume fraction of nanoparticles, with high Young modulus and low Poisson ratio. The results indicate the performance of nanoparticles in improving thermomechanical behavior of building materials, and also in other applications.

Characterization of belitic cement mortars elaborated from shell and glass powders, microstructure and mechanical properties

The purpose of this study is to use waste glass as a source of silicium oxide SiO2 and shells as a source of calcium carbonate CaCO3 to replace traditional raw materials for the production of belite-rich clinkers and to investigate the hydration characteristics of the resulting mortars. After grinding, the raw materials were mixed to synthesize the belite phase in a heat treatment from 500 °C to 1000 °C. The belitic clinkers were, mixed with shell powder (CaCO3) and gypsum. The cements were synthesized with different proportions of belitic clinker and the hydration of the mortars was performed by increasing the percentage of belitic clinkers. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the mineralogy of hydrated samples during different curing times of 28, 65 and 90 days. The mechanical strength of mortars was measured for 28, 65 and 90 days. The results obtained show that the strength of all the samples increases with the curing time. The mortar containing 56 % of C2S has the highest value of mechanical strength 30.05 Mpa after 90 days of curing compared to other mortars. We have attempted here to review the development of high-belite cements by simple heat treatment at relatively low temperature and low CO2 release.

An approach to using foraminifera in sequence stratigraphic analysis of Wadi Qena, Central Eastern Desert, Egypt

In Egypt, Wadi Qena Middle Eastern Desert, Paleogene successions exposed at Hawashiya and Abu Had sections from north to south were measured and comprehensively investigated for their foraminiferal content. The Dakhla, Tarawan, and Esna formations make up the investigated sections. The studied successions are subdivided into six biozones; they are five zones of the Late Paleocene (Igorina albeari subzone (P3b), G. Globanomalina pseudomenardii/P. Parasubbotina variospira subzone (P4a), Acarinina subsphaerica subzone (P4b), A. soldadoensis/G. pseudomenardii subzone (P4c), Morozovella velascoensis zone (P5), and one zone of the Early Eocene (P. Pseudohastigerina wilcoxensis/M. velascoensis zone (E2). The paleoenvironmental interpretations and interpretation of sea level changes over the study area during the Paleocene-Eocene time interval have been carried out based on the lithostratigraphy, biostratigraphy, paleoecologic parameters (total foraminiferal number (TFN), diversity indices of foraminifera, life strategies of planktonic foraminifera, planktonic/benthonic (P/B) foraminiferal ratio, agglutinated/calcareous benthonic foraminiferal ratios, benthonic foraminiferal biofacies and total organic carbon (TOC), and calcium carbonate CaCo3%). Five sequences are identified in the studied Lower Paleogene successions in the Wadi Qena area. Four depositional sequences are determined in the Paleocene, and one in the Lower Eocene. A comprehensive description of these depositional sequences and their boundaries is provided. The findings of the current study are calibrated with sequence stratigraphy of the world sea-level variations.

Evaluating the Potentials of PLSR and SVR Models for Soil Properties Prediction Using Field Imaging, Laboratory VNIR Spectroscopy and Their Combination

Pedo-spectroscopy has the potential to provide valuable information about soil physical, chemical, and biological properties. Nowadays, we may predict soil properties using VNIR field imaging spectra (IS) such as Prisma satellite data or laboratory spectra (LS). The primary goal of this study is to investigate machine learning models namely Partial Least Squares Regression (PLSR) and Support Vector Regression (SVR) for the prediction of several soil properties, including clay, sand, silt, organic matter, nitrate NO3-, and calcium carbonate CaCO3, using five VNIR spectra dataset combinations (% IS, % LS) as follows: C1 (0% IS, 100% LS), C2 (20% IS, 80% LS), C3 (50% IS, 50% LS), C4 (80% IS, 20% LS) and C5 (100% IS, 0% LS). Soil samples were collected at bare soils and at the upper (0–30 cm) layer. The data set has been split into a training dataset 80% of the collected data (n = 248) and a validation dataset 20% of the collected data (n = 61). The proposed PLSR and SVR models were trained then tested for each dataset combination. According to our results, SVR outperforms PLSR for both: C1 (0% IS, 100% LS) and C5 (100% IS, 0% LS). For Soil Organic Matter (SOM) prediction, it achieves (R2 = 0.79%, RMSE = 1.42%) and (R2 = 0.76%, RMSE = 1.3%), respectively. The data fusion has improved the soil property prediction. The highest improvement was obtained for the SOM property (R2 = 0.80%, RMSE = 1.39) when using the SVR model and applying the second Combination C2 (20% of IS and 80% LS).

Microporous Ceramics Based on β-Tricalcium Phosphate

Microporous ceramic material, based on β-tricalcium phosphate β-Ca3(PO4)2 with grain size 2–5 μm, pore size smaller than 10 mm, and density 1.22 g/cm3 corresponding to ~40% of the theoretical density (3.07 g/cm3) of β-Ca3(PO4)2, was obtained from a powder mixture with a given molar ratio Ca/P = 1.5 after firing at 1100 °C. A homogenized powder mixture of synthetic dicalcium hydrogen phosphates with the molar ratio Ca/P = 1 and calcium citrate tetrahydrate Ca3(C6H5O7)2·4H2O with the molar ratio Ca/P = ∞ was used for microporous ceramic preparation. The phase composition of calcium phosphate powder, synthesized from an aqueous solution of phosphoric acid H3PO4 and calcium carbonate CaCO3 powder, included brushite CaHPO4·2H2O as the predominant phase. Formation of β-tricalcium phosphate β-Ca3(PO4)2 during firing occurred due to the heterophase interaction of the products of thermal decomposition of the components of the starting powder mixture, namely, calcium pyrophosphate Ca2P2O7 and calcium oxide CaO. The formation of arch-like structures from β-tricalcium phosphate β-Ca3(PO4)2 grains, which were tightly sintered together, hindered the shrinkage of ceramics. The microporous ceramics obtained, based on β-tricalcium phosphate β-Ca3(PO4)2, can be recommended as a biocompatible and biodegradable material for treatment of bone defects and as a substrate for bone-cell cultivation.

Cascade System for Biomineralization in Cement: Project, Construction and Operationalization to Enhance Building Energy Efficiency

Anthropogenic and natural actions cause internal and external fractures in concrete. To recover these structures, bio-concretes have been developed with bacteria of the genus Bacillus. These microorganisms consume calcium lactate, synthesize calcium carbonate and biomineralize CaCO3 crystals within the structures of concrete. The aim of the present study was to construct equipment, denominated “Cascade System for Biomineralization in Cement” (CSBC), to determine the limiting velocity of the biomineralization of CaCO3. The construction of the equipment took into consideration chemical and biochemical phenomena responsible for biomineralization. Parts made with 3D printing and a circuit with Arduino UNO R3 board were used in the assembly of the system. The prototype proved to be stable and can be considered a promising tool for future application in research of the regeneration of reinforced concreted in a practical, fast and economical way, especially to the energy sector.