CaCO3 Levels Research Articles

Analysis of the Effect of Crystal form on Precipitated Calcium Carbonate (PCC) of Dead Coral Reefs with the Addition of HNO3 Concentration

Many dead coral reefs found on the coast have not been treated optimally and currently their use is still limited as decoration in aquariums. Coral reefs contain calcium carbonate, silicon dioxide, sodium oxide, magnesium peroxide, and Iron (III) oxide, with a calcium carbonate content of around 73.76%. Because of its high calcium carbonate content, it can be used as a raw material for making PCC (Precipitated Calcium Carbonate) which is widely used in the industrial, health and food sectors. The aim of this research is to obtain the optimal temperature and time for CaO levels, as well as the effect of nitric acid solution concentration on the yield with a high level of purity in PCC products using the carbonization method. The fixed variables are: coral reef mass, independent variables: temperature, calcination time and nitric acid concentration and dependent variables: CaO yield and CaCO3 levels. The calcination temperature used was 700℃, 750℃, 800℃, 850℃, 900℃ and HNO3 concentration 1.50M, 2.00M, 2.50 M, 3.00M, 3.50M with Ca analysis using AAS and PCC morphology and content using SEM-EDX. Optimal conditions are the results of calcination at a temperature of 900℃ with an HNO3 concentration of 3.50 M resulting in a yield of 76% with a purity of 98.58%, pH 8, white with a Ca concentration (ppm) of 1,962,630 and the crystal form obtained at 3.00 M HNO3 is calcite and 3.50 M HNO3 is vaterite.

Karakterisasi Alat Filtrasi Air Portable Berdasarkan Variasi Jumlah Absorber Karbon Aktif Limbah Tongkol Jagung

Sumbawa Regency is an area with soil water content containing lime. There was even lime blockage in the pipe holes used. So this research aims to create a portable filtration device that is cheap and efficient. The aim of this research is to characterize a portable water filtration device with an innovative absorber from corncob waste. The way this research works is the process of carbonizing corn cob waste and then activating it using 0.5 M NaOH for 24 hours. The absorber is then filled into a portable filter with dimensions of 50 cm in length and 4 inches in diameter. Filtration is carried out by flowing the collected well water into the water reservoir through a filter. Tests are carried out on water that has not been passed through a filter. After that, characterization was also carried out on the water that had passed through the filter. This characterization consists of Total Dispended Solid (TDS), Temperature, pH, Ca levels, and turbidity. The TDS value obtained decreases with the increasing number of absorbers used, namely from 203, 163, to 123 ppm. In addition, the temperature of the test water has almost no change. The resulting results were temperatures of 32, 33, and 32oC. The resulting pH value shows a decrease with an increase in the number of absorbers used, namely from 8.3; 7.7; 7.3. For turbidity, there was a decrease in the turbidity rate with an increase in the number of absorbers used, namely from 0.29 NTU to 0.3 NTU, and 0.28 NTU. In addition, CaCO3 levels decreased with an increase in the number of absorbers used, namely from 330 mg/l, 290 mg/l, and 240 mg/l. This value has met the threshold set by PMK No. 32 of 2017.

FTIR and XRD Characterization of the Cements Available in Commercial Market of Nepal

In the engineering material characterizations and analytical domains where the specific physicochemical properties of the materials are probed through various sophisticated instrumental tools and techniques, the XRD and FTIR spectroscopy stand as the standalone applications as the former discloses the crystallographic structure, crystallite/grain sizes, and the chemical compositions of the specific materials nondestructively while the latter reveals details about the IR active vibrations modes of each covalent bond of their chemical constituents. In the present studies, we employ both of these techniques, and characterize the specifically selected variable manufactured ready-to-use dry OPC type cements available in the commercial markets of Nepal. The former technique derived the specific 2\(\theta\) value deterministic for identifying the closely packed interatomic layers with the significant levels of CaCO3, Ca(OH)2, and arsenic As5+ based AsO43- unit bearing crystalline phases in each samples. The calculated crystallite sizes of them are found as equal as that reported for the calcite based OPC cements, and are directly adopted to depict their utmost intermixing propensities with the carbon dust and hence, act as the most potential evidence of unlocking the possibility of inventing cement-carbon composites based supercapacitors and conductive devices, and of speculating their distinguishable hydration rates and setting times. And, the latter technique produced intense IR active bands in the designated wave number regions are used to confirm their silicate (SiO42-) tetrahedra, amorphous CaCO3 phases & the CO32-unit holding chemical constituents, 2CaO.SiO2 and 3CaO.SiO2 type chemical compounds explicitly. The presence of diffused type IR bands specific to the Al2O3 based chemical compounds signified that all of them contains significant levels of the alumina based hardening elements, but the complete absence of the peak typical to the Mg-O signified that none of them contains magnesia. The similar analyses of the IR bands further reveal that none of them possesses heavy and active type CaCO3, but have trace amounts of the AsO43- based chemical compounds as predicted by the XRD. The intensive peak area and the depth intensity studies of the designated IR bands speculate the dissimilar quantitative proportions and percentage compositions of these chemical constituents in them. The authors believe that the general results presented herewith illuminate the fundamental chemical constituents to be incorporated compulsorily into the OPC type cements so that they function normally and exhibit good cementitious abilities.

Adhesion and Cohesion Strength of Phenol-Formaldehyde Resin Mixed with Different Types and Levels of Catalyst for Wood Composites

Phenol-formaldehyde (PF) resin is one of the most well-known adhesives for exterior use. PF adhesive is one of the commercial thermoset polymers that is used extensively due to its many benefits. This study investigated the influence of different types and levels of catalysts, i.e., NaOH and CaCO3 at 1% and 5% based on the solids content of PF resin on the adhesive properties, adhesion, and cohesion strength of PF resin. The results show that the catalyst type significantly influenced the PF adhesive viscosity and pH. Furthermore, the catalyst level significantly affected the PF adhesive’s solids content, viscosity, and gelation time. The cohesion strength of PF-CaCO3-1% was more significant than the PF control at 75 °C. According to the DMA analysis, the mixed PF-NaOH-5% provided the highest storage modulus, followed by the PF-CaCO3-1%, with values that were not statistically different from one another. The adhesion strength of PF-CaCO3-1% was the highest, whereas the adhesion strength of the PF control was the lowest, as confirmed by the cohesion strength. According to the findings, adding CaCO3-1% as a catalyst of PF resin would result in better adhesive adhesion and cohesion properties for wood composites in the future.

The Effectiveness of Slow Sand Filtration on Reduction of Iron (Fe) and Calcium (CaCO3) Levels in Water

Ground water or well water is the largest source of clean water used. The most common obstacle in using groundwater is the problem of iron (Fe) and calcium (CaC03) content in raw water. This research aims to determine the effectiveness of slow sand filtration to reduce Fe and CaCO3 levels in water. This type of research is a pure experimental study in a re-treatment design (One Group Pretest Posttest). The samples of raw water were taken from water pump wells owned by residents on JI. Datu Adam, Lere Village. Sample testing after slow sand filtering was carried out at the UPTD Laboratory of the Office of Environment, Donggala. The filter was carried out with a medium thickness of 45 cm sand, 5 cm gravel sand, 7 cm gravel and 5 cm high puddle water. Before filtering the test results Fe 0.4mg/L and CaCO3 546.37mg/L. Based on the effectiveness test of slow sand filtration with 3 treatments, it was found that the levels of substances after filtering were iron (Fe) 0.29, 0.21 and 0.I2 mg/L respectively, while calcium (CaCO3) was 273.41, 241.35 and 210.11 mg/L respectively. From these results, slow sand filtration is effective in reducing Fe and CaCO3 levels in water. The community is expected to be able to use simple filtering media such as slow sand filters to reduce iron (Fe) and calcium (CaCO3) levels in water. It is also expected to provide additional knowledge studies in the field of public health, especially environmental health.

Effect of dietary macronutrient composition and buffering capacity on chyme characteristics and digestion kinetics in the gastrointestinal tract of freshwater rainbow trout (Oncorhynchus mykiss)

The aim of this study was to investigate the impact of dietary macronutrient composition and buffering capacity (BC) on chyme characteristics and digestion kinetics in freshwater rainbow trout (Oncorhynchus mykiss). Dietary macronutrient composition was altered by changing the protein-to-energy ratio (P:E) while keeping the fat-to-starch ratio constant. Dietary BC was increased by supplementation of CaCO3. The experiment lasted for 6 weeks. Fish were fed four diets having high and low P:E ratio and high and low CaCO3 level. This experiment was planned according to a 2x2x2 factorial design. The three factors were dietary P:E ratio, BC and time sampling after feeding (3 and 7 h). Chyme was collected from four gastrointestinal tract (GIT) segments (stomach, proximal, middle and distal intestine) and analysed for dry matter (DM), pH, osmolality, crude protein (CP) and mineral content. Relative water fluxes (RWF), electrolyte fluxes, kinetic of digestion and faecal digestibility (ADCs) were measured using yttrium oxide (Y2O3) as an inert marker. All chyme characteristics (including water fluxes) were not influenced by the interaction effect between dietary factors and sampling time (p > 0.05). Both dietary treatments did not affect chyme DM in the stomach. Low P:E diet increased (p < 0.001) chyme DM in all the intestinal segments. Dietary CaCO3 only affected (p < 0.05) chyme DM in the distal intestine. Low P:E diet decreased (p < 0.001) chyme pH in all GIT segments compared to the high P:E diet. Low CaCO3 diet decreased chyme pH in the proximal and middle intestine (p < 0.05) compared to the high CaCO3 diet. RWF were affected only by the dietary P:E ratio in the stomach and in the proximal intestine. Fish fed the high P:E diet had a lower water influx in the stomach and a higher water influx in the proximal intestine than fish fed the low P:E diet. Dietary P:E ratio affected electrolyte fluxes in the GIT, while no effect of CaCO3 was detected. Both dietary factors had a minimal or no effect on the kinetic of digestion in the different GIT segments, while a significant effect was present in all ADCs. Our findings suggest that dietary macronutrient composition, rather than buffering capacity, is the primary factor responsible for changes in chyme characteristics, water and ion fluxes in the GIT of freshwater rainbow trout. Furthermore, changes in dietary macronutrient composition and buffering capacity significantly affect faecal digestibility but are not reflected in digestion kinetics.

Tara (Caesalpinia spinosa) in Natural and Agroforestry Systems under an Altitudinal Gradient in the Peruvian Andes: Responses to Soil and Climate Variation

This research examined how edaphoclimatic variations are related to dendrometric variables of the Tara tree in natural and agroforestry systems in Cajamarca, Peru. Evaluations followed three approaches: (a) principal components analysis (PCA) with environmental factors and altitude classes with 1 °C of temperature variation for edaphic and dendrometric variables; (b) evaluation of possible differences by the bootstrap method for the different variables in the PCAs; and (c) correlation analysis between plant density, plant and crown height, stem and crown diameter, and the number of stem branches with the physical and chemical attributes of the soil and with air temperature. In the altitudinal gradient from 2021 to 3007 ± 7 m, the temperature ranged from 19.8 to 13.4 ± 0.4 °C; the soils possessed alkaline pH, high organic matter (OM), K and CEC, lower contents of CaCO3, N, P, K, B, Cu, Fe, Mn, and Zn. The soil properties with the most significant contribution to PCAs were OM, CEC, N content, and sand, with no variation among environments but among altitudes. None of the dendrometric variables varied as a function of altitude and temperature in PCAs run in the natural environment. However, in the agroforestry environment, there was a greater crown diameter, and tree and crown height in the 2185 m altitude class associated with Medicago sativa. In contrast, the opposite behavior was found in these variables and in the altitude class 2798 m associated with low Fe content, and already in the altitude class at 3007 m, a larger stem diameter is associated with higher levels of CaCO3. The anthropic effect on the agroforestry environment did not significantly alter the soil’s CEC, OM, N, and sand. Tara’s crown diameter and tree height appeared higher in agroforestry environments. The variations of Fe and CaCO3 in the soil might have influence on the development of Tara individuals in natural and agroforestry environments. It is important to carry out further studies for a better understanding of the relationship between the production of Tara pods and soil fertility in altitudinal variation, aiming to improve the income and employment of family farmers who exploit Tara in the Peruvian Andes.

Effect of added calcium carbonate without and with benzoic acid on weanling pig growth performance, fecal dry matter, and blood Ca and P concentrations

Abstract The objective of these studies was to determine the effects of increasing levels of calcium carbonate (CaCO3) with and without benzoic acid on weanling pig growth performance, fecal dry matter (DM), and blood Ca and P concentrations. In experiment 1, 695 pigs (DNA Line 200 × 400, initially 5.9 ± 0.02 kg) were used in a 28 d study. Pigs were weaned at approximately 21 d of age and randomly assigned to pens and then pens were allotted to one of five dietary treatments. Treatment diets were fed from weaning (day 0) to day 14, with a common diet fed from days 14 to 28. Dietary treatments were formulated to provide 0%, 0.45%, 0.90%, 1.35%, and 1.80% added CaCO3 at the expense of ground corn. From days 0 to 14 (treatment period), average daily gain (ADG) and G:F decreased (linear, P ≤ 0.01) as CaCO3 increased. From days 14 to 28 (common period) and for the overall experiment (days 0 to 28), there was no evidence of differences in growth performance between treatments. For fecal DM, there was a trend (quadratic, P = 0.091) where pigs fed with the highest CaCO3 diets had the greatest fecal DM. Experiment 2 used 360 pigs (DNA Line 200 × 400, initially 6.2 ± 0.03 kg) in a 38 d study. Upon arrival to the nursery facility, pigs were randomly assigned to pens and then pens were allotted to one of six dietary treatments. Dietary treatments were fed in three phases with treatment diets fed from days 0 to 10 and days 10 to 24, and a common phase 3 diet fed from days 24 to 38. Dietary treatments were formulated to provide 0.45%, 0.90%, and 1.35% added CaCO3 with or without 0.5% benzoic acid (VevoVitall, DSM Nutritional Products, Parsippany, NJ) added at the expense of ground corn. There was no evidence (P &amp;gt; 0.05) for any CaCO3 by benzoic acid interactions. For the experimental period (days 0 to 24), there was a tendency for benzoic acid to increase ADG (P = 0.056), average daily feed intake (ADFI; P = 0.071), and gain-to-feed ratio (G:F; linear, P = 0.014) as CaCO3 decreased. During the common period (days 24 to 38), pigs previously fed benzoic acid had increased (P = 0.045) ADG and marginally increased (P = 0.091) ADFI. For the overall study, pigs fed benzoic acid had increased ADG (P = 0.011) and ADFI (P = 0.030), marginally increased G:F (P = 0.096) and final body weight (P = 0.059). Serum Ca decreased (linear, P &amp;lt; 0.001) as CaCO3 decreased in the diet. These data show that decreasing the CaCO3 content in the nursery diet immediately after weaning may improve ADG and G:F. Dietary addition of benzoic acid may also provide beneficial effects on ADG and ADFI, regardless of dietary Ca level.

Analisis Kandungan Kalsium Karbonat (CaCO3) Batu Gamping Di Kelurahan Bontoa Kecamatan Minasate’ne Kabupaten Pangkajene Dan Kepulauan

&#x0D; The research had been carried out with the aim of finding out and analyzing the quality of the calcium carbonate content (CaCO3) of limestone as a raw material for making marble. To determine the CaCO3 content, the method was using gravimetric method by weighing empty beaker mass parameter, and the mass of sample and beaker plus HCl 2N level as the final mass after the reaction. The used sample consist of two blocks, they were block one on the coordinate point of 4º48’-4º51’ LS and 119º35’-119º37’ BT and block two on the coordinate point of 4º47’-4º51’ LS and 119º37’-119º39’ BT. The sampling technique was using a chisel and hammer. The result of the research shows that the average of CaCO3 content at the two sampling points was obtained each of 85,530 % and 84,6897%. It is obtained that the level of CaCO3 in the limestone meets the Standar Industri Indonesia (SII) requirement, which is above 50% and it means that the sampling point in Bontoa village, Minasate’ne district, Pangkajene Regency and Island able to be used as marble raw material. &#x0D;

Solubilization of phosphorus by low molecular weight organic acids and amino acids in calcareous soils

In order for plants to perform well in nutrient-deficient calcareous soils, they have an efficient adaptive technique of root exudate secretion, which contains low molecular weight organic acids. They enhance nutrient release and thereby increase the nutrient availability in calcareous soils. The present study aimed to investigate the effect of concentration and time of incubation of low molecular weight organic acids on P solubilization from calcareous soils collected from various locations of Coimbatore district with varying levels of calcareousness. An incubation experiment was conducted with five calcareous soils with varying levels of free CaCO3 viz., (1, 7.5, 12.5, 17.5 &amp; 21.5%) by incubating with seven different concentrations (0, 20, 40, 60, 80 &amp; 100 mM) of four organic (citric, malic, oxalic and acetic acid) and two amino acids (glycine and lysine) for nine incubation time intervals (5, 10, 20, 30, 60, 120, 240, 960 &amp; 1440 mins) on a factorial experiment based on completely randomized design (CRD). Available P was analyzed to find the solubilization efficiency of various organic and amino acids. The organic acids were more efficient when compared to amino acids in P solubilization, especially citric acid followed by oxalic and malic acids, at 100 mM concentration incubated for 1440 mins. Also, the solubilization increased with increasing concentration and incubation time, irrespective of the soil calcareousness, but the magnitude of phosphorus extraction decreased with increasing soil calcareousness. Incubating the calcareous soils with 100 mM of citric acid for 1440 min solubilized more amount of phosphorus. Hence it can be concluded that addition of 100 mM citric acid will influence the phosphorus release even from highly calcareous soils.

ANALISIS PENCEMARAN KUALITAS KIMIA AIR SUMUR DANGKAL DI PERMUKIMAN KUMUH RW IV KELURAHAN BANGKA JAKARTA SELATAN

Use of groundwater as a water source in South Jakarta is quite high with a usage value of 3,768,226 m3. Most of the shallow groundwater in RW IV Bangka village are at a depth of &lt;25 mbgl, so they have the potential to be polluted.. Moreover that village categorized as slums area, where there is high risk to be polluted by poor environment. . This study aims to analyze the level quality of Fe and CaCO3 pollution and their correlation with the risk factors in shallow well water in RW IV Bangka Village. This type of research is analytic observational with a cross sectional approach. The research population was the total number of wells in the residential area of RW IV, with the research sample using purposive random sampling of 30 shallow wells. The results showed that 100% of the samples met the requirements for pH (x̄= 8,0) and CaCO3 (x̄= 253 mg/l) levels. Meanwhile, for Fe (x̄= 0,29 mg/l) value , there were 7 samples (23,2%) that did not meet the requirements. Chi-square statistical analysis showed that there was no relationship between latrine distance (p=0,666), distance of other pollutants (p=0,675), standing water around the well (p=1,00), and SPAL conditions (p=0,304) with the Fe quality in shallow well water. However, based on the prevalence ratio (PR), the highest risk was found in other pollutant distance factors compare to others (PR=1,524). The conclusion that, although the levels of Fe and CaCO3 in shallow well water are quite high, statistical analysis shows that there is no correlation from environment risk factors for these two value levels by reason, most of well type for sampling is bore well type which is low for contamination.

Combined application of calcium carbonate and NPKS fertilizer improves early-stage growth of poplar in acid soils

The cultivation of Populus spp. on acid soils is difficult mainly due to low nutrient availability, limiting the distribution and use of this marketable tree species. In this paper we report the results of two experiments, in which a granulated highly reactive micronized calcium carbonate (CaCO3) was tested at increasing levels to improve the effect of NPKS fertilization on poplar growth. Twin field and pot experiments were carried out in 2017 using two different poplar clones, both of which are often used in Italy. In addition to analysing the data from the two experiments separately, common patterns were evaluated using a mixed-effect model with CaCO3 level and fertilization as fixed effects, and the experiment type as random effect. Growth was assessed in terms of total height, diameter and biomass. Taken together, the results from the two experiments showed that fertilization led to enhanced growth of poplar, but this effect was stronger when soil conditions in terms of pH and exchangeable Ca were at a sufficiently high level. Available nutrient concentrations in the soil and foliar nutrient concentrations in the plant suggested co-limitation of poplar growth by N and Ca. In conclusion, the results of this study on one hand emphasize the importance of adapting the level of CaCO3 to the given soil conditions, and on the other hand ask for further studies addressing the relative importance of elevated pH and improved Ca nutrition.

Geospatial Distribution of Iron in Major Sugarcane Growing Soils of Sivagangai, Tamil Nadu, India

The present study was undertaken to assess the available DTPA iron status in the major sugarcane growing soils of Southern Sivangai district, Tamil Nadu, India. A total of 500 geo referenced surface (0-30 cm) were collected from five blocks viz., Kalaiyarkovil, Padamathur, Sivagangai, Thiruppachetty and Thiruppuvanam and analyzed for basic soil properties and available DTPA iron. Simple correlation was worked out to ascertain the degree of relationship between soil properties and available DTPA iron content of soil study area. The available DTPA iron in the entire sugarcane growing soils ranged from 2.95 to 5.79 mg kg-1, 2.11 to 4.31 mg kg-1, 3.49 to 5.59 mg kg-1, 1.99 to 5.66 mg kg-1 and 3.94 to 6.39 mg kg-1 in soil samples of Kalaiyarkovil, Padamathur, Sivagangai, Thiruppachetty and Thiruppuvanam respectively. In the soil samples from Kalaiyarkovil, Padamathur, Sivagangai, Thiruppachetty, and Thiruppuvanam, the results revealed that 52, 59, 55, 53, and 51 % of the soils were deficient in available iron and 33, 29, 35, 30 and 32 % of the soils were moderate in available iron, and 15, 12, 10,5 and 17 % of the soils were sufficient in available iron. As per the nutrient index study, the soils of study area recorded very low to low fertility rating for available iron and the mean nutrient index value (NIV) ranged from 1.42 to 1.64 in the soil of the study area. SOC and CEC were found to have a beneficial impact on iron availability, whereas EC and CaCO3 levels had a negative impact on DTPA iron availability.

Calcium Carbonate Particles Filled Homopolymer Polypropylene at Different Loading Levels: Mechanical Properties Characterization and Materials Failure Analysis

Calcium carbonate (CaCO3) particles have been widely used in filling thermoplastics for different applications in automotive, packaging, and construction. No agreement has been reached in the research community regarding the function of CaCO3 for enhancing toughness of homopolymer polypropylene (HPP). This study was to understand the effect of different loading levels of CaCO3 on HPP toughness, including notched and unnotched impact strength. A batch mixer was used to thermally compound CaCO3 particles with HPP at loading levels of 10, 20, 30, 40, and 50 wt.%, followed by specimen preparation using an injection molding process. The mechanical properties of the composites, including tensile, flexural, and impact were characterized. The results indicated that tensile strengths decreased significantly with increasing loading levels of CaCO3 particles while the tensile and flexural modulus increased significantly with increasing particle loadings. The composite tensile properties changed linearly with increasing CaCO3 loadings. The notched Izod impact strength of the composites was sustained by adding CaCO3 particles up to 40 wt.% while the unnotched impact strength decreased significantly with the addition of CaCO3 particles. Different deformation mechanisms between notched (fracture propagation) and unnotched (fracture initiation and propagation) impact tests were proposed to be the reason.

Selected physicochemical properties and sensory acceptability as affected by addition of lecithin and calcium carbonate in extruded breakfast cereals made with silkworm pupae powder and rice flour

SummaryEffects of Lecithin (LC):Calcium carbonate (CaCO3) ratios (0.00:0.50, 0.10:0.40, 0.25:0.25, 0.40:0.10 and 0.50:0.00%w/w) on selected physicochemical properties and sensory acceptability of extruded breakfast cereals made with silkworm (Samia ricini D.) pupae powder and rice flour were investigated. The control sample was made without LC:CaCO3. Compared to the control, addition of LC significantly (P ≤ 0.05) reduced sectional expansion index, water solubility index and hardness, while increasing L*, bulk density and water absorption index of the samples. Increasing the CaCO3 level decreased bulk density while increased L*, ΔE*, sectional expansion index and crispness. The LC:CaCO3 interaction influenced aw, moisture, porosity and sensory liking, especially at 0.10:0.40%w/w which was suitable to produce the breakfast cereals. All samples had a protein content between 31.70% and 33.76% (dry basis), which made them qualified as a “high‐protein” source. The white malt–honey flavour coating increased liking scores of the finished product compared to the uncoated ones.

Characterization of a Novel CaCO3-Forming Alkali-Tolerant Rhodococcus erythreus S26 as a Filling Agent for Repairing Concrete Cracks.

Biomineralization, a well-known natural phenomenon associated with various microbial species, is being studied to protect and strengthen building materials such as concrete. We characterized Rhodococcus erythreus S26, a novel urease-producing bacterium exhibiting CaCO3-forming activity, and investigated its ability in repairing concrete cracks for the development of environment-friendly sealants. Strain S26 grown in solid medium formed spherical and polygonal CaCO3 crystals. The S26 cells grown in a urea-containing liquid medium caused culture fluid alkalinization and increased CaCO3 levels, indicating that ureolysis was responsible for CaCO3 formation. Urease activity and CaCO3 formation increased with incubation time, reaching a maximum of 2054 U/min/mL and 3.83 g/L, respectively, at day four. The maximum CaCO3 formation was achieved when calcium lactate was used as the calcium source, followed by calcium gluconate. Although cell growth was observed after the induction period at pH 10.5, strain S26 could grow at a wide range of pH 4–10.5, showing its high alkali tolerance. FESEM showed rhombohedral crystals of 20–60 µm in size. EDX analysis indicated the presence of calcium, carbon, and oxygen in the crystals. XRD confirmed these crystals as CaCO3 containing calcite and vaterite. Furthermore, R. erythreus S26 successfully repaired the artificially induced large cracks of 0.4–0.6 mm width.

Improved Method of Boron Fertilization in Rice (Oryza sativa L.)–Mustard (Brassica juncea L.) Cropping System in Upland Calcareous Soils

Calcareous soils are highly deficient in boron (B) due to having high levels of free CaCO3 and low organic matter. This has become one of the most important deficient micronutrients in Indian soil after zinc (Zn). For various rice (Oryza sativa L.)-based cropping systems, B fertilization is essential for increasing crop productivity and the biofortification of the crop, thus a suitable soil application protocol for B fertilization is required for B-deficient soils. In a six-year experiment, different rates of B application, namely, 0.5, 1.0, 1.5, and 2.0 kg ha−1 y−1, were evaluated to determine the effects of three different modes of B fertilization, i.e., applied only in the first year, applied in alternating years, and applied every year, in a rice (Oryza sativa L.)–Indian mustard (Brassica juncea L.) cropping system. It was observed that the application of B at 1.5 kg ha−1 every year or 2 kg ha−1 in alternate years resulted in the highest yield of rice and mustard, as well as the maximum system productivity of the rice–mustard cropping system. Application of 2 kg ha−1 of B in the initial year showed the maximum B uptake by rice, while application of 1.5–2.0 kg ha−1 of B every year resulted in the maximum B uptake by the mustard crop. Application of B at 2 kg ha−1 in alternate years or 1.5 kg ha−1 every year was the best B-application protocol in B-deficient calcareous soils for ensuring the highest productivity of the rice–mustard cropping system and B availability in the soil.

Pengaruh Variasi Kadar CaCO3 terhadap Pertumbuhan Fase Superkonduktor BPSCCO–2212 Menggunakan Metode Pencampuran Basah

This research was conducted to determine the effect of CaCO3 levels on the formation of superconducting phase BPSCCO - 2212 by calculating the level of purity of the phases formed and looking at the microstructure. The variation of CaCO3 was 0.95, 1.00, 1.05 and 1.10 mole using the wet mixing method. The samples were calcined at 800 ° C for 10 hours, and sintered at 820 ° C for 20 hours. Synthesized samples were characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The XRD’s chacterization results show that the level of purity of the formed phases increases with increasing Ca levels with maximum point at BPSCCO-2212/1.10 mole. The highest volume fraction was 79,06% in the BPSCCO-2212/1.10 sample. While the lowest volume fraction was 72.10% in the BPSCCO-2212/0.95 sample. Meanwhile, the highest degree of orientation was 20.59% at BPSCCO-2212/0.95. The lowest degree of orientation was 8.46% at BPSCCO-2212/1.10. SEM’s chacterization results show of all samples have been oriented altought not perfect yet and have relatively little space between slabs (voids).

Metal Bioaccumulation by the Neotropical Clam Anomalocardia flexuosa to Estimate the Quality of Estuarine Sediments.

This investigation evaluated the bioaccumulation potential of the tropical estuarine bivalve Anomalocardia flexuosa for trace metals. To this aim, chemical and sedimentological analyses and bioaccumulation tests were performed. The sediments were mainly composed by fine-sands and mud, with variable levels of organic matter and CaCO3. Muddy sediments from a depositional site (P2) presented the highest concentrations of metals, despite SEM/AVS not indicating bioavailability. Bioaccumulation factors showed high ratios for Cd, Ni, and Zn, while associations between the contents of mud, organic matter, CaCO3 and metals in sediments and tissues of A. flexuosa were indicated by a principal component analysis. The SEM/AVS was not effective to predict the bioavailability through dissolved metals. The results showed that contaminants were bioavailable, while the performed bioaccumulation test proved to be a reliable technique for assessing sediment contamination in estuarine regions. Moreover, A. flexuosa was considered an adequate test organism for bioaccumulation studies.

Pemanfaatan Cangkang Telur Puyuh Sebagai Pengikat Logam Berat Timbal (Pb) dalam Air

Timbal (Pb) adalah logam berat yang bersifat toxic. Pb dapat membahayakan lingkungan dan kesehatan organisme. Beberapa limbah bahan organic memungkinkan digunakan sebagai pengikat logam berat. Cangkang telur puyuh mengandung CaCO3 sebesar 55,46%, sehingga memungkinkan untuk dijadikan adsorben untuk menyerap logam berat seperti Pb. Tujuan penelitian ini untuk menganalisis perbedaan kadar Pb pada air yang tidak diberi limbah serbuk cangkang telur puyuh yaitu 0 gr/l (P0) dan diberi perlakuan serbuk cangkang telur puyuh teraktivasi termal pada suhu 800°C dengan variasi massa 1,5 g/l (P1),3,5 g/l (P2), dan 5,5 g/l. Selanjutnya, dilakukan pengadukan menggunakan Jar Test dengan kecepatan 250 rpm selama 10 menit dan didiamkan selama 30 menit. Penelitian ini merupakan penelitian adalah True Experiment dengan Rancangan Acak Lengkap. Data dianalisis menggunakan uji One Way Anova dengan α = 0,05. Hasil menunjukkan bahwa terdapat perbedaan signifikan antara kelompok kontrol dengan kelompok perlakuan (p-value&lt; 0,0001). Perbedaan paling signifikan terjadi pada kelompok penambahan serbuk cangkang telur puyuh teraktivasi sebanyak 5,5 g/l (P3) memiliki penurunan tertinggi dari pada kelompok lainnya yaitu dengan persentase 85,71 %. Cangkang telur puyuh dapat mengikat cemaran timbal (Pb) dalam air.