Formation Of Calcium Carbonate Deposits Research Articles

Effect of Surface Modification on the Characteristics of Sisal Fiber Reinforced Concrete Treated with Na2CO3

Concrete with fiber as a reinforcing material is one of the important fields of research that is gaining traction in this upcoming green technology revolution. By adding fibers to concrete, the tensile strength properties are vastly improved without compromising the strength characteristics, and cost fluctuation is minimal. This research is being carried out to improve the qualities of concrete that have been infused with chemically treated sisal fiber in varied ratios. The paper investigates and describes the effects of sisal fiber when it is chemically treated and infused with concrete, comparing it to ordinary concrete in strength tests. Water absorption, workability, and other material characteristics of Sisal fiber reinforced concrete with 0.5 per cent, 1 per cent, 1.5 per cent, and 2 per cent fiber replacing cement by volume fraction and a sisal fiber aspect ratio of 1:100 are compared to the traditional M30 concrete grade. After being treated with an alkaline solution, 0.5 per cent and 1 per cent sisal fiber reinforced concrete increased tensile and compressive strength, as well as the formation of calcium carbonate deposits on the fiber interfaces; this also contributes to the concrete’s corrosion resistance and durability.

Microbiologically Induced Carbonate Precipitation in the Restoration and Conservation of Cultural Heritage Materials.

Microbiologically induced carbonate precipitation (MICP) is a well-known biogeochemical process that allows the formation of calcium carbonate deposits in the extracellular environment. The high concentration of carbonate and calcium ions on the bacterial surface, which serves as nucleation sites, promotes the calcium carbonate precipitation filling and binding deteriorated materials. Historic buildings and artwork, especially those present in open sites, are susceptible to enhanced weathering resulting from environmental agents, interaction with physical-chemical pollutants, and living organisms, among others. In this work, some published variations of a novel and ecological surface treatment of heritage structures based on MICP are presented and compared. This method has shown to be successful as a restoration, consolidation, and conservation tool for improvement of mechanical properties and prevention of unwanted gas and fluid migration from historical materials. The treatment has revealed best results on porous media matrixes; nevertheless, it can also be applied on soil, marble, concrete, clay, rocks, and limestone. MICP is proposed as a potentially safe and powerful procedure for efficient conservation of worldwide heritage structures.

Inhibition of scaling water of Tiznit region by "LEVALL®10".

Combating the formation of calcium carbonate deposits in potable water pipes presents a challenge for water treatment systems, The use of inhibitors is one of the best techniques to prevent or delay the formation of these deposits. It is therefore essential to find a new generation of scale inhibitors, which is distinguished, on the one hand, by a better inhibiting effectiveness of calcium carbonate, and, on the other hand, by their ecological effect due to the respect of health and environment norms.

The Effect of Hydrogen Absorption on the Passivity of Oxides on Carbon Steels

Pipelines are designed for a wide variety of applications. Their use in the energy sector for the transportation of crude oil, natural gas, and other petrochemical commodities is still regarded as the safest, fastest and most economical mode of product transmission and delivery. The degradation of the structural integrity of pipelines caused by corrosion has been an on-going problem. Depending on in-service use, different forms of corrosion can occur, with the deleterious effects depending on which type of corrosion is occurring, such as stress corrosion cracking (SCC) and hydrogen induced cracking (HIC) due to hydrogen embrittlement (HE). Further, the hydrogen may affect the protectiveness of any FeIII oxide present on the steel surface. This study investigates the effects of H absorption by X60, X65, X70 steels. A range of electrochemical techniques, such as monitoring the corrosion potential (Ecorr), polarization resistance (Rp) measurements, cyclic voltammetry (CV), and H permeation experiments (using the Devanathan-Stachurski (D-S) approach) have been used to investigate the effect of H on the steel and the oxides present on the steel surface. Surface analytical techniques such as X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were used to determine the effect of H on the composition of the oxide and to identify the distribution of H trapping sites. The apparent diffusivity of H in X65 was found to depend on the composition of the solution on the reduction side of the D-S cell. The steady-state current measured in the oxidation cell was dependent on the solution composition in the reduction cell. The presence of calcium caused a sharp decrease of oxidation current, likely due to the quick formation of calcium carbonate deposits, whereas magnesium caused a gradual decrease in the observed oxidation current, which is likely due to the thickening of the magnesium hydroxide on the surface. The presence of both calcium and magnesium in the solution affects the amount of H that diffuses through the steel, likely by blocking adsorption sites on the steel surface. Blocked adsorption sites reduce the concentration of atomic hydrogen on the surface and lead to a decrease in the observed steady-state current. Thermal desorption data show that, in the X65 steel, a majority of the H trapped within the steel requires activation energy (Ea) of < 50 kJ/mol for its release, indicating that it is located in reversible trapping sites. SIMS data suggest that trapping occurs predominantly along grain boundaries, with the extent of H trapping at these sites possibly affecting the resistance of the surface FeIII oxides present. The RP values measured after cathodic charging for the pearlite-containing steel (X65) were lower than those obtained on the bainite-containing steel (X70). The presence of FeO on the steel surface after cathodic charging suggests partial oxide reduction, with this reduced oxide being more prominent on the X65 than on the X70 steel. Polarization resistance measurements were used to study the role of hydrogen on the passivity of the steel covered by iron oxides. It has been shown that at open circuit conditions the increase in RP value is slower when the steel has been charged with H. The phase of X70 being investigated was predominantly bainite, which is more resistive to hydrogen absorption. X70, after hydrogen charging, was found to have a lesser change in steady-state RP than did the X65. Further, the retardation of the resistance increase at open circuit was more prominent on the X65 than on the X70. XPS confirmed that more FeO was present on the X65 sample after charging than on the X65 after charging followed by potentiodynamic polarization experiments. All this suggests that, at open circuit conditions after the steel was charged with H, hydrogen being released from reversible trapping sites reduces the FeIII oxide to FeO. The reduction of FeIII to FeO, due to either the charging or release of atomic hydrogen trapped within the lattice, is likely causing a decrease in the resistance of the passive oxide.

Architecture in Aqueous Flux: The CaCO3 Depositional House

A petrifying well in northern England inspired architect James Eagle to explore how crystallisation could be applied to architecture. Begun as his fifth‐year MArch thesis at the University of Greenwich, London, and further developed thereafter, his proposals for the CaCO3 Depositional House use porous templates and cybernetics to guide the formation of calcium carbonate deposits into fantastical yet functional structures, from windows to sanitary facilities. He describes the process, the project, the prototype, and its implications for architecture's future.

Determination of the effectiveness of new green scale inhibitors for reverse osmosis

The effectiveness of a number the test samples of new antiscalants (lightly crosslinked polymers of acrylic and methacrylic acids and crosslinking agents based on allyl ethers and other compounds, and a copolymer of maleic anhydride and methacrylic acid) has been experimentally compared with that of traditionally used scale inhibitors based on hydroxyethylidene diphosphonic acid, nitrilotriphosphonic acid, and the commercial inhibitor Aminat-K. The results of the experimental study of the kinetics of formation and buildup of the crystalline deposit of calcium carbonate in the presence and the absence of scale inhibitors depending on the composition of feedwater and the yield of a filtrate are reported. The experiments have been performed with the use of feedwater from the Moscow water-supply line. Equations for determining the rates of formation of calcium carbonate deposits in membrane devices in the presence of an inhibitor depending on the chemical composition of feedwater and the filtrate yield have been derived; these equations make it possible to recommend a work-cycle time before chemical cleaning operations.

Ultrastructural evidence for transepithelial calcium transport in the anterior sternal epithelium of the terrestrial isopod Porcellio scaber (Crustacea) during the formation and resorption of CaCO 3 deposits

Before the molt, terrestrial isopods store large amounts of calcium carbonate between the epithelium and the old cuticle of the first four anterior sternites. In order to test whether the anterior sternal epithelium has specific structural differentiations indicative of transepithelial ion transport, the anterior sternal epithelium and, as a control, the posterior sternal epithelium were studied using electron-microscopical techniques. During the formation of calcium carbonate deposits, the basolateral plasma membrane of the anterior sternal epithelium forms an elaborate interconnected network of interstitial dilations and channels. Numerous osmiophilic granules occur within this basolateral intercellular network during resorption of the calcium carbonate deposits. Electron energy-loss spectroscopy of the osmiophilic granules indicates that they contain calcium. During the resorption of the calcium carbonate deposits, the apical plasma membrane of the anterior sternal epithelium has many subcuticular folds. An interstitial network, osmiophilic granules, and apical, subcuticular folds do not occur in the posterior sternal epithelium. Taken together, these structural features are indicative of transepithelial ion transport and are probably necessary for the formation and resorption of the anterior sternal calcium carbonate deposits.