scholarly journals Forecasting the durability of reinforced concrete under conditions of microbiological corrosion

2021 ◽  
Vol 274 ◽  
pp. 04003
Author(s):  
Konstantin Strokin ◽  
Denis Novikov ◽  
Viktoriya Konovalova
Keyword(s):  
Aspergillus Niger ◽  
Calcium Hydroxide ◽  
Vital Activity ◽  
Cement Concrete ◽  
Microbiological Corrosion ◽  
Concrete Corrosion ◽  
Calcium Cations ◽  
Equilibrium Concentrations ◽  
Bacterial Corrosion ◽  
Kinetics Of

The article presents data on the study of the kinetics of liquid corrosion of cement concrete infected with microorganisms Bacillus subtilis and Aspergillus niger. The equilibrium concentrations of calcium cations during fungal and bacterial corrosion of cement concrete in an aqueous medium are established. According to the profiles of calcium hydroxide concentrations in the thickness of cement concrete during fungal and bacterial corrosion, it was found that during fungal corrosion of concrete, the intensity of interaction of calcium hydroxide with the products of the vital activity of microorganisms is higher than during bacterial corrosion. In case of fungal corrosion under conditions of Aspergillus niger infection, citric acid has the greatest impact on concrete since its amount in the products of the vital activity of microorganisms is maximum. Profiles of concentrations of aggressive substances by the thickness of the concrete sample show that bacterial corrosion proceeds more slowly than fungal corrosion and allow us to calculate the time to reach the maximum concentration of aggressive substances at the surface of steel reinforcement in concrete. Corrosion of reinforcement in concrete with fungal corrosion will begin in 2.5 years after infection, with bacterial corrosion after 5.5 years.

The kinetics of the autolytic phase of growth in cultures of Aspergillus niger

1986 ◽  
Vol 94 (2) ◽  
pp. 75-78 ◽  
Author(s):  
R. Lahoz ◽  
F. Reyes ◽  
G. G�mez Alarc�n ◽  
L. Cribeiro ◽  
M. A. Junquera ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Kinetics Of

Low Cement/High Fly Ash Concretes: Their Properties and Response to Chemical Admixtures

1987 ◽  
Vol 113 ◽  
Author(s):  
V. H. Dodson
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Calcium Hydroxide ◽  
Pozzolanic Reaction ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Fly Ashes ◽  
Chemical Admixtures ◽  
Reaction With Water

ABSTRACTIn practice, the amount of fly ash added to portland cement concrete varies depending upon the desired end properties of the concrete. Generally, when a given portland cement concrete is redesigned to include fly ash, between 10 and 50% of the cement is replaced by a volume of fly ash equal to that of the cement. Sometimes as much as twice the volume of the cement replaced, although 45.4 kg (100 lbs) of cement will only produce enough calcium hydroxide during its reaction with water to react with about 9 kg (20 lbs) of a typical fly ash. The combination of large amounts of certain fly ashes with small amounts of portland cement in concrete has been found to produce surprisingly high compressive strengths, which cannot be accounted for by the conventional “pozzolanic reaction”. Ratios of cement to fly ash as high as 1:15 by weight can produce compressive strengths of 20.7 MPa (3,000 psi) at I day and over 41.4 MPa (6,000 psi) at 28 days. Methods of identifying these “hyperactive” fly ashes along with some of the startling results, with and without chemical admixtures are described.

scholarly journals Kinetic Study of the Recovery of Phosphorus from Wastewater by Calcium Hydroxide Solution

2019 ◽  
Vol 25 (6) ◽  
pp. 19-29
Author(s):  
Shams Asem Mahdi ◽  
Raghad Fareed Qasim
Keyword(s):  
Oxalic Acid ◽  
Calcium Hydroxide ◽  
Phosphorus Concentration ◽  
Ambient Conditions ◽  
Residual Phosphorus ◽  
Mixing Speed ◽  
Dissolution Reaction ◽  
Best Value ◽  
Percentage Removal ◽  
Kinetics Of

This research presents a study for precipitating phosphorus (as phosphate ion) from simulated wastewater (5ppm initial concentration of phosphorus) using calcium hydroxide Ca(OH)2 solution. The removal of phosphorus by Ca (OH)2 solution is expected to be very effective since the chemical reaction is of acid-base type but Ca(OH)2 forms complex compound with phosphate ions called. Hydroxyapatite Ca5 (PO4)3OH. hydroxyapatite is slightly soluble in water. This research was directed towards sustainable elements as phosphorus. Kinetics of the dissolution reaction of hydroxyapatite was investigated to find the best factors to recover phosphorus. The effect of concentration of Ca(OH)2 (180- 380 ppm) on phosphorus precipitation on the outputs like the residual phosphorus concentration in the simulated solution, the percentage removal of phosphorus and the weight of the precipitate was also studied. The residual phosphorus decreased with increasing Ca(OH)2 concentration while the percentage removal, as well as the weight of the precipitate, increased with increasing Ca(OH)2 concentration at constant temperature and mixing speed. The best Ca(OH)2 concentration was obtained depending on the lowest amount of the residual phosphorus concentration. The best value obtained was 230 ppm at a fixed mixing speed of 400 rpm and a temperature of 20°C.  The best value for Ca(OH)2 concentration under fixed stirring speed and temperature was applied on a real wastewater taken from the detergent factory. The percentage removal was 30. 69% due to the complexity of the real sample. Oxalic acid was chosen to dissolve hydroxyapatite because it is an organic acid, less hazardous than mineral acids and of less cost. Kinetics of the dissolution reaction of hydroxyapatite in (160 ppm) concentration oxalic acid under ambient conditions (20°C and 1 atm (and mild stirring (200 rpm) was studied using the differential method for determining the order of the reaction which was 0.4296 and the rate constant 0.0743 (L/mg)-0.5704. min-1. The reaction was considered as a rate-controlled reaction.  

Kinetics of Aspergillus niger growth at high glucose concentrations in different types of the cultures

1997 ◽  
pp. 49-58 ◽  
Author(s):  
E. Favela-Torres ◽  
M. García-Rivero ◽  
J. Cordova-López ◽  
S. Roussos ◽  
G. Viniegra-González ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
High Glucose ◽  
Different Types ◽  
Kinetics Of

scholarly journals Tunable Mn Oxidation State and Redox Potential of Birnessite Coexisting with Aqueous Mn(II) in Mildly Acidic Environments

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 690
Author(s):  
Juan Liu ◽  
Yixiao Zhang ◽  
Qian Gu ◽  
Anxu Sheng ◽  
Baogang Zhang
Keyword(s):  
Oxidation State ◽  
Organic Pollutant ◽  
Equilibrium Concentration ◽  
Aquatic Environments ◽  
Oxidation Potentials ◽  
Average Oxidation State ◽  
Subsurface Environments ◽  
Equilibrium Concentrations ◽  
Kinetics Of ◽  
Manganese Oxide Mineral

As the dominant manganese oxide mineral phase in terrestrial and aquatic environments, birnessite plays an important role in many biogeochemical processes. The coexistence of birnessite with aqueous Mn2+ is commonly found in the subsurface environments undergoing Mn redox cycling. This study investigates the change in Mn average oxidation state (AOS) of birnessite after reaction with 0.1–0.4 mM Mn2+ at pH 4.5–6.5, under conditions in which phase transformation of birnessite by Mn2+ was not detectable. The amount of Mn2+ uptake by birnessite and the equilibrium concentration of Mn(III) proportionally increased with the initial concentration of Mn2+. The Mn AOS of birnessite particles became 3.87, 3.75, 3.64, and 3.53, respectively, after reaction with 0.1, 0.2, 0.3, and 0.4 mM Mn2+ at pH 5.5. Oxidation potentials (Eh) of birnessite with different AOS values were estimated using the equilibrium concentrations of hydroquinone oxidized by the birnessite samples, indicating that Eh was linearly proportional to AOS. The oxidation kinetics of bisphenol A (BPA), a model organic pollutant, by birnessite suggest that the logarithms of surface area-normalized pseudo-first-order initial rate constants (log kSA) for BPA degradation by birnessite were linearly correlated with the Eh or AOS values of birnessite with AOS greater than 3.64.

Microbiological Corrosion in Waterfloods

CORROSION ◽  
1961 ◽  
Vol 17 (8) ◽  
pp. 386t-390t ◽  
Author(s):  
J. M. SHARPLEY
Keyword(s):  
Corrosion Damage ◽  
Field Evaluation ◽  
Suggested Method ◽  
Microbial Flora ◽  
Microbiological Corrosion ◽  
Sulfate Reducing ◽  
Bacterial Corrosion ◽  
Reducing Bacteria ◽  
Evaluation Techniques

Abstract It is commonly observed that most bacterial corrosion in waterfloods occurs as pit corrosion. A hypothesis has been advanced to explain a portion of the mechanism underlying bacterial pit corrosion and a suggested method has been presented for determining the possible relationships between the general microbial flora and microorganisms capable of participating in pit corrosion. Topics discussed include role of sulfate-reducing bacteria, correlation between bacteriological examinations and corrosion damage, cultural techniques, laboratory and field evaluation techniques, and detection of sessile microorganisms. 3.3.4, 3.2.2, 8.4.3

Kinetics of growth of Aspergillus niger during submerged, agar surface and solid state fermentations

1998 ◽  
Vol 33 (2) ◽  
pp. 103-107 ◽  
Author(s):  
E. Favela-Torres ◽  
J. Cordova-López ◽  
M. García-Rivero ◽  
M. Gutiérrez-Rojas
Keyword(s):  
Solid State ◽  
Aspergillus Niger ◽  
Agar Surface ◽  
Kinetics Of
Sign in / Sign up

Export Citation Format

Share Document