The Role of Manganese Carbonate Precipitation in Controlling Fluoride and Uranium Mobilization in Groundwater

2021 ◽  
Author(s):  
Ashwini Kumar Mohapatra ◽  
Surya Sujathan ◽  
Aravinth S. S. Ekamparam ◽  
Abhas Singh
Keyword(s):  
Manganese Carbonate ◽  
Carbonate Precipitation

scholarly journals The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charalampos Konstantinou ◽  
Yuze Wang ◽  
Giovanna Biscontin ◽  
Kenichi Soga
Keyword(s):  
Calcium Carbonate ◽  
Calcium Chloride ◽  
Urease Activity ◽  
Coarse Sand ◽  
Carbonate Precipitation ◽  
Population Densities ◽  
Carbonate Cements ◽  
Microbially Induced Carbonate Precipitation

AbstractProtocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise the process with regard to the amount of injected chemicals, the ratio of urea to calcium chloride, the method of injection and injection intervals, and the population of the bacteria, usually using fine- to medium-grained poorly graded sands. This study assesses the effect of varying urease activities, which have not been studied systematically, and population densities of the bacteria on the uniformity of cementation in very coarse sands (considered poor candidates for treatment). A procedure for producing bacteria with the desired urease activities was developed and qPCR tests were conducted to measure the counts of the RNA of the Ure-C genes. Sand biocementaton experiments followed, showing that slower rates of MICP reactions promote more effective and uniform cementation. Lowering urease activity, in particular, results in progressively more uniformly cemented samples and it is proven to be effective enough when its value is less than 10 mmol/L/h. The work presented highlights the importance of urease activity in controlling the quality and quantity of calcium carbonate cements.

Non-stoichiometric hydrated magnesium-doped calcium carbonate precipitation in ethanol

2019 ◽  
Vol 55 (86) ◽  
pp. 12944-12947 ◽  
Author(s):  
Giulia Magnabosco ◽  
Andrea M. M. Condorelli ◽  
Rose Rosenberg ◽  
Iryna Polishchuk ◽  
Boaz Pokroy ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Crystallization Process ◽  
Ion Solvation ◽  
Absolute Ethanol ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation

The effect of Mg2+ on the precipitation pathway of CaCO3 in absolute ethanol has been studied to investigate the role of ion solvation in the crystallization process.

scholarly journals Modeling and Optimization of Manganese Carbonate Precipitation Using Response Surface Methodology and Central Composite Rotatable Design

2021 ◽  
Vol 7 (3) ◽  
Author(s):  
Meschack Mukunga Muanda ◽  
Pele Pascal Daniel Omalanga
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Ph Value ◽  
Sulfate Solution ◽  
Magnesium Carbonate ◽  
Manganese Carbonate ◽  
Carbonate Precipitation ◽  
Optimum Conditions ◽  
Solution Ph ◽  
Central Composite

A sulfate solution containing 1773.965 mg/L Mn2+, 3216.178 mg/L Mg2+ and 566.254 mg/L Ca2+ was used to perform the maximum recovery of manganese and minimum recovery of magnesium. Carbonate precipitation was used due to the better selectivity for manganese over magnesium and other impurities recovery compared to hydroxide precipitation. Four factors were studied: solution pH value, contact time, reaction temperature and sodium carbonate consumption. Analysis of variance (ANOVA) and response surface methodology (RSM) were used to determine the optimum. Under the optimum conditions, the manganese and magnesium recoveries were the highest and the lowest respectively, while the pH, the time, the temperature and the volume of Na2CO3 were the lowest.  The values of the four factors were found as followed: 8.9293, 60.69 min, 77.95°F, and 50.7650 mL respectively. Moreover, the recoveries of manganese and magnesium were 99.9799% and 4.3045% respectively. The results show that optimization using RSM is effective in improving carbonate precipitation of manganese.

scholarly journals Role of Na-Montmorillonite on Microbially Induced Calcium Carbonate Precipitation

Molecules ◽  
2021 ◽  
Vol 26 (20) ◽  
pp. 6211
Author(s):  
Guowang Tang ◽  
Cangqin Jia ◽  
Guihe Wang ◽  
Peizhi Yu ◽  
Haonan Zhang
Keyword(s):  
Calcium Carbonate ◽  
Sandy Soil ◽  
Carbonate Precipitation ◽  
Soil Consolidation ◽  
X Ray Diffraction ◽  
Calcium Carbonate Precipitation ◽  
X Ray ◽  
Significant Attention ◽  
Previous Reaction

The use of additives has generated significant attention due to their extensive application in the microbially induced calcium carbonate precipitation (MICP) process. This study aims to discuss the effects of Na-montmorillonite (Na-MMT) on CaCO3 crystallization and sandy soil consolidation through the MICP process. Compared with the traditional MICP method, a larger amount of CaCO3 precipitate was obtained. Moreover, the reaction of Ca2+ ions was accelerated, and bacteria were absorbed by a small amount of Na-MMT. Meanwhile, an increase in the total cementing solution (TCS) was not conducive to the previous reaction. This problem was solved by conducting the reaction with Na-MMT. The polymorphs and morphologies of the CaCO3 precipitates were tested by using X-ray diffraction and scanning electron microscopy. Further, when Na-MMT was used, the morphology of CaCO3 changed from an individual precipitate to agglomerations of the precipitate. Compared to the experiments without Na-MMT in the MICP process, the addition of Na-MMT significantly reduced the hydraulic conductivity (HC) of sandy soil consolidated.

Carbonate precipitation in the alkaline lake Specchio di Venere (Pantelleria Island, Italy) and the possible role of microbial mats

2016 ◽  
Vol 67 ◽  
pp. 168-176 ◽  
Author(s):  
Marianna Cangemi ◽  
Paolo Censi ◽  
Andreas Reimer ◽  
Walter D'Alessandro ◽  
Dorothea Hause-Reitner ◽  
...  
Keyword(s):  
Microbial Mats ◽  
Carbonate Precipitation ◽  
Alkaline Lake
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