Calcite Seeds Research Articles

High-level of bio-cementation by microbially induced carbonate precipitation technique with nano calcite seeds

The bio-cementation process through bacterial mineralization has emerged as an eco-friendly solution for soft or loose sandy soils, particularly in areas with ground slopes and high rainfall. This approach is aligned with sustainable development goals, promoting environmentally responsible and long-lasting solutions. In this context, ureolytic bacteria capable of decomposing urea for calcium carbonate precipitation are the primary agents for bio-cementation. This study explores the effects of nano calcite as nucleation sites on the MICP capacity to enhance the bio-cementation process. The microstructure of the precipitation was analyzed alongside its capacity for MICP. In addition, a simulated rainfall model was set up to evaluate the erosion resistance of sand samples. The findings of this study can guide the development of eco-friendly solutions for soil stabilization in environmentally vulnerable areas.

Different skeletal protein toolkits achieve similar structure and performance in the tropical coral Stylophora pistillata and the temperate Oculina patagonica

Stony corals (order: Scleractinia) differ in growth form and structure. While stony corals have gained the ability to form their aragonite skeleton once in their evolution, the suite of proteins involved in skeletogenesis is different for different coral species. This led to the conclusion that the organic portion of their skeleton can undergo rapid evolutionary changes by independently evolving new biomineralization-related proteins. Here, we used liquid chromatography-tandem mass spectrometry to sequence skeletogenic proteins extracted from the encrusting temperate coral Oculina patagonica. We compare it to the previously published skeletal proteome of the branching subtropical corals Stylophora pistillata as both are regarded as highly resilient to environmental changes. We further characterized the skeletal organic matrix (OM) composition of both taxa and tested their effects on the mineral formation using a series of overgrowth experiments on calcite seeds. We found that each species utilizes a different set of proteins containing different amino acid compositions and achieve a different morphology modification capacity on calcite overgrowth. Our results further support the hypothesis that the different coral taxa utilize a species-specific protein set comprised of independent gene co-option to construct their own unique organic matrix framework. While the protein set differs between species, the specific predicted roles of the whole set appear to underline similar functional roles. They include assisting in forming the extracellular matrix, nucleation of the mineral and cell signaling. Nevertheless, the different composition might be the reason for the varying organization of the mineral growth in the presence of a particular skeletal OM, ultimately forming their distinct morphologies.

Extreme halophilic bacteria promote the surface dolomitization of calcite crystals in solutions with various magnesium concentrations

In this study, we conducted experiments on the transformation from calcite to protodolomite using bacteria. The surface dolomitization of calcite seed crystals was initiated by Vibrio harveyi J4, a newly isolated extreme halophilic bacterium, under increasing magnesium concentrations of 0, 0.05, 0.10, 0.15, to 0.20 mol L–1. The mineralogy, surface morphology, elemental composition, and lattice structure of the calcite crystals before and after bacterial treatment were analyzed by XRD, SEM-EDS, AFM and TEM, respectively. Organic functional groups within newly-formed minerals were determined by FTIR and XPS. The weight loss of minerals in the experimental group and control groups was measured by TGA and DSC. The experiments resulted in numerous nano-spheroidal-hemispheroidal precipitates being formed on the surface of the calcite seeds, whereas dissolution took place on the calcite crystal surfaces in control experiments with no bacteria. The nano-spheroids-hemispheroids were confirmed to be disordered protodolomite. The number of protodolomite spheroids on the calcite crystal surfaces increases dramatically with increasing concentration of magnesium. Since no calcium ions were added to the bioreactor, the protodolomite nano-spheroids-hemispheroids are considered to have been formed through some dissolution of the calcite to provide the Ca2+ ions in a local precipitation process. The mechanism of protodolomite precipitation is thought to be related to the presence of acidic amino acids and polysaccharides in the EPS of the extreme halophilic bacteria. These results suggest that in addition to promoting the precipitation of dolomite, micro-organisms may also play a key role in the dolomitization of calcite.

Insights into microbially mediated cementation in modern beachrock in the Xisha Islands, South China Sea

The present paper supplies biological and lithological evidence for the mechanisms of biochemical cementation in modern beachrocks on the tropical Yongle Atoll, Xiasha Islands in the South China Sea. High-throughput sequencing was used to precisely determine the epilithic microbial community in beachrocks. Microscopic mineralogical examination of sedimentary grains further showed complex processes from rapid carbonate precipitation. The results from 18/16 s rRNA diversity examination indicated that green algae and cyanobacteria only occupied a small proportion of the community, albeit they had considerable amounts. The occurrences of Lyngbya (Family Oscillatoriaceae), Calothrix and Dichothrix (Family Rivulariaceae) with light colour may be related to calcified sheaths coated on the living cells. The short rod-like Mg calcite in Lyngbya sheaths and anhedral to euhedral Mg calcite in Calothrix or Dichothrix sheaths were organominerals mediated most likely by photosynthesis of microorganisms with chloroplasts. Different initial crystal patterns were closely related to different cyanobacterial extracellular polymeric substance (EPS) structures. After cell death, these microcrystals were released into the voids and removed by interstitial water. The carbonate seeds scattered all around the particle surface and then began to enlarge the grain size with the degradation of organic matter. Different paths of crystal growth eventually cemented the intertidal grains abiotically or biotically. This case sheds light on cryptic microbially mediated mineralization in beachrock. Even though chemical processes were considerable in the formation of the beachrocks on the modern reef flat, the pervasive microbial geological processes occurred quietly but effectively. • Epilithic biotic communities in the beachrock were studied by genetic sequencing. • Cyanobacteria filaments Lyngbya , Calothrix and Dichothrix have calcified sheaths. • Magnesium calcite seeds in cyanobacterial EPS are biominerals. • Microbially-mediated carbonates rapidly consolidate the beachrock.

Influence of precipitation rate and temperature on the partitioning of magnesium and strontium in calcite overgrowths

To study the incorporation of magnesium (Mg) and strontium (Sr) in calcite precipitated over synthetic calcite seeds (overgrowths) as a function of the precipitation rate (R*, μmol/m2 h), we performed precipitation experiments wherein temperature and precipitation rates were decoupled at intervals of approximately 3.63–5.22 μmol/m2 h. In most sample reactions, high‑magnesium calcite (HMC) overgrowths co-precipitated with aragonite from the stirred solutions exposed to an atmosphere of NH3 and CO2 gases throughout the spontaneous decomposition of (NH4)2CO3. The percentage of aragonite in the solid CaCO3 increased with both temperature and dissolved inorganic carbon (DIC). The order of reaction with respect to the [DIC] is temperature dependent and is 1.9, 2.4, and 2.9 at temperatures of 12.5, 25.0, and 37.5 °C, respectively. The magnesium distribution coefficient (DMg) increases significantly with increasing R*, temperature, and Mg/Ca ratio in the fluid. The strontium distribution coefficient (DSr) increases with R* and with increasing MgCO3 concentrations in the calcite overgrowths. However, it is independent of temperature.

Application Of Seeding Crystallization as a Pre-Treatment Stage for The Reduction of Scaling Tendency of Seawater Feed to Thermal Desalination Units

Objective: The fouling inhibition in seawater desalination and scale control using crystallization with calcite seeds is evaluated experimentally in this study. Methods: The growth kinetic parameters are determined experimentally, correlated and discussed at different operating conditions. Supersaturation levels represent driving force behind the growth of crystals, which is influenced directly by seawater pH values and temperatures. Results: Results indicate that the initial pH value of seawater must be controlled to be in the range (8-9) and calcite seeds will not have the potential to start the growth process in seawater at the normal pH (7.36). The growth kinetic parameters are determined from the measured desupersaturation curves. Conclusion: It is found that the growth process of calcite is controlled by the surface integration step. The growth rate of calcite increases with increasing temperature and seeding ratio (up to 1 g/L), while it decreases with increasing the salinity of seawater.

A sample cell for the study of enzyme-induced carbonate precipitation at the grain-scale and its implications for biocementation

Biocementation is commonly based on microbial-induced carbonate precipitation (MICP) or enzyme-induced carbonate precipitation (EICP), where biomineralization of text {CaCO}_{3} in a granular medium is used to produce a sustainable, consolidated porous material. The successful implementation of biocementation in large-scale applications requires detailed knowledge about the micro-scale processes of text {CaCO}_{3} precipitation and grain consolidation. For this purpose, we present a microscopy sample cell that enables real time and in situ observations of the precipitation of text {CaCO}_{3} in the presence of sand grains and calcite seeds. In this study, the sample cell is used in combination with confocal laser scanning microscopy (CLSM) which allows the monitoring in situ of local pH during the reaction. The sample cell can be disassembled at the end of the experiment, so that the precipitated crystals can be characterized with Raman microspectroscopy and scanning electron microscopy (SEM) without disturbing the sample. The combination of the real time and in situ monitoring of the precipitation process with the possibility to characterize the precipitated crystals without further sample processing, offers a powerful tool for knowledge-based improvements of biocementation.

Calcite seed-assisted microbial induced carbonate precipitation (MICP).

Microbial-induced calcium carbonate precipitation (MICP) is a biological process inducing biomineralization of CaCO3. This can be used to form a solid, concrete-like material. To be able to use MICP successfully to produce solid materials, it is important to understand the formation process of the material in detail. It is well known that crystallization surfaces can influence the precipitation process. Therefore, we present in this contribution a systematic study investigating the influence of calcite seeds on the MICP process. We focus on the changes in the pH and changes of the optical density (OD) signal measured with absorption spectroscopy to analyze the precipitation process. Furthermore, optical microscopy was used to visualize the precipitation processes in the sample and connect them to changes in the pH and OD. We show, that there is a significant difference in the pH evolution between samples with and without calcite seeds present and that the shape of the pH evolution and the changes in OD can give detailed information about the mineral precipitation and transformations. In the presented experiments we show, that amorphous calcium carbonate (ACC) can also precipitate in the presence of initial calcite seeds and this can have implications for consolidated MICP materials.

Carbonation reactivity enhancement of γ-C2S through biomineralization

Most of the calcium silicates exhibit high carbonation reactivity, and thus start to be utilized in the production of low carbon concrete due to the growing pressure of carbon mitigation in the cement industry. In this study, powdered γ-C2S, with limited hydraulicity, is preconditioned in a suspension consisting of urease-producing bacterium and urea. This biomineralization process induces the precipitation on the γ-C2S surface of calcite crystals with spherical shape, the size of which is dependent on the urea suspension concentration. The effect of the pre-existing calcite crystals on the carbonation behavior, mechanical and micro-morphology of γ-C2S compacts is investigated. Results indicate the compressive strength are significantly improved with the pre-existing calcite crystals, and the increasing percentage is 43.66 % at 30 min carbonation and 0.25 mol/L urea concentration. The strength enhancement is found to be associated with the pre-existing calcite crystals acting as nucleation seeds which accelerate the carbonation at the early stage. In addition, the pre-existing calcite seeds induce the preferential formation of calcite in the crystalline carbonation products of γ-C2S, which may be beneficial to the enhancement of the carbonated products.

Growth of calcite seeds in a magnetized environment

Using the constant-composition technique, the growth rates of calcite seeds in a simulated cooling-water environment, i.e., at a temperature higher than room temperature and in the presence of impurity, were measured in a stirred-tank crystallizer under the influence of a magnetic field. When the impurity was absent, the magnetic field would gradually reduce the growth rate of calcite seeds and would have varying impact on the time needed for the seeds to stop growing for different levels of supersaturation, temperature, and pH. In the presence of impurities, including Sr2+ and Fe2+ in the concentration range between 0 and 2.0ppm, the growth experiments were conducted at two temperatures, i.e., 25°C and 35°C. In the presence of Sr2+ the calcite seeds grew steadily after a premagnetization time of 20h, which was long enough to completely stop the growth of calcite seeds in the absence of impurities. On the other hand, the effect of Fe2+ on calcite growth rate in the presence of magnetic field was rather complicated; either reduced or enhanced rate has been observed. The magnetic field indeed inhibited or stopped the growth of calcite seed for some instances.

Influence of etidronic acid and tartaric acid on the growth of different calcite morphologies

AbstractThe influence of organic additives on the crystal growth of different calcite morphologies in two crystallization processes operating under steady state and batch mode is described. The crystal growth kinetics and overgrown morphological observations of rhombohedral, scalenohedral and prismatic calcite seed crystals in the systems containing etidronic acid (HEDP) and tartaric acid (TA) were investigated. The crystallization systems were of low supersaturations (SI<1.1) and of moderate pH (8.0). Kinetic parameters of the crystal growth in the presence of selected additives, such as reduction of the growth rates, rate constant and reduced critical supersaturation were calculated and correlated with additive concentration and different calcite seeds. The results indicate strong interactions of HEDP molecules and weak but specific interactions of TA for calcite surfaces. Interactions occur at the step edges which finally results in the expression of near-{hk0} faces and highly polar faces, consisting of solely Ca layer on the surface, stabilised by TA and HEDP molecules, respectively. The affinity of both additives is significantly higher for scalenohedral and prismatic calcite in contrast to rhombohedral calcite seeds. The effect of calcite seed morphology was attributed to different surface energetics of the predominant crystal faces of the studied calcite seeds.

Dissolved sulfide-catalyzed precipitation of disordered dolomite: Implications for the formation mechanism of sedimentary dolomite

Dolomite is a common mineral in the rock record. However, the rarity of modern dolomite and the notorious difficulty in synthesizing dolomite abiotically under normal Earth-surface conditions result in the long-standing “dolomite problem” in sedimentary geology. Some modern dolomites are associated with sediments where microbial sulfate reduction is active; however, the role of sulfate-reducing bacteria in dolomite formation is still under debate. In this study, we tested the effect of dissolved sulfide on the precipitation of Ca–Mg carbonates, which has been never explored before although dissolved sulfide is one of the major products of microbial sulfate reduction. Our results demonstrated that dissolved sulfide with a concentration of as low as several millimoles can enhance the Mg2+ incorporation into the calcitic structure, and promote the crystallization of high magnesian calcite and disordered dolomite. We also conducted seeded precipitation in experimental solutions containing dissolved sulfide, which showed that calcite seeds can inhibit the precipitation of aragonite and monohydrocalcite (CaCO3·H2O), and induce more Mg2+ incorporation. We propose that accumulated dissolved sulfide in pore waters in organic-rich sediments may trigger the precipitation of disordered dolomite which can be considered as a precursor of some sedimentary dolomite. Our adsorption experiments revealed a strong adsorption of dissolved sulfide onto calcite faces. We suggest that adsorbed dissolved sulfide can lower the energy barrier to the dehydration of Mg2+–water complexes on the growing carbonate surfaces. This study sheds new light on understanding the role of sulfate-reducing bacteria in dolomite formation and the formation mechanism of sedimentary dolomite.

Calcite Reinforced Silica–Silica Joints in the Biocomposite Skeleton of Deep‐Sea Glass Sponges

AbstractThe hierarchically structured glass sponge Caulophacus species uses the first known example of a silica and calcite biocomposite to join the spicules of its skeleton together. In the stalk and body skeleton of this poorly known deep‐sea glass sponge siliceous spicules are modified by the addition of conical calcite seeds, which then form the basis for further silica secretion to form a spinose region. Spinose regions on adjacent spicules are then joined by siliceous crosslinks, leading to unusually strong cross‐spicule linkages. In addition to the biomaterials implications it is now clear, from this first record of a biomineral other than silica, that the hexactinellid sponges are capable of synthesizing calcite, the ancestral skeletal material. We propose that, while the low concentrations of calcium in deep sea waters drove the evolution of silica skeletons, the brittleness of silica has led to retention of the more resilient calcite in very low concentrations at the skeletal joints.

Synergetic effects of temperature and magnetic field on the aragonite and calcite growth

The effects of temperature and magnetic field on aragonite and calcite growth were investigated in a stirred-tank crystallizer, using the constant-composition technique. At room temperature without magnetization, the calcite seeds grew but the aragonite did not. When the growth rates of the aragonite and calcite seeds were measured in the presence of a magnetic field at temperatures above room temperature, the synergetic effects were significant but with differing effects on the different seeds. The cluster-transformation mechanism was used to explain the growth rate data. Finally, the aragonite growth rate data were compared with data obtained in a fluidized bed.

Visualization of acoustic cavitation effects on suspended calcite crystals

The acoustic cavitation (42,080 Hz, 7.1 W cm −2 or 17 W) effects on suspended calcite crystals, sized between 5 and 50 μm, have been visualized for the first time using high speed photography. High speed recordings with a duration of 1 s containing up to 300,000 frames per second, revealed the effect of cluster and streamer cavitation on several calcite crystals. Cavitation clusters, evolved from cavitation inception and collapse, caused attrition, disruption of aggregates and deagglomeration, whereas streamer cavitation was observed to cause deagglomeration only. Cavitation on the surface gave the crystals momentum. However, it is shown that breakage of accelerated crystals by interparticle collisions is unrealistic because of their small sizes and low velocities. Crystals that were accelerated by bubble expansion, subsequently experienced a deceleration much stronger than expected from drag forces, upon bubble collapse. Experiments with pre-dried crystals seemed to support the current theory on bubble nucleation through the presence of pre-existing gas pockets. However, experiments with fully wetted crystals also showed the nucleation of bubbles on the crystal surface. Although microjet impingement on the crystal surface could not be directly visualized with high speed photography, scanning electron microscopy (SEM) analysis of irradiated calcite seeds showed deep circular indentations. It was suggested that these indentations might be caused by shockwave induced jet impingement. Furthermore, the appearance of voluminous fragments with large planes of fracture indicated that acoustic cavitation can also cause the breakage of single crystal structures.

Application of seeded batch crystallization methods for reduction of the scaling tendency of seawater – A study of growth kinetics of calcium carbonate in seawater

AbstractThe objective of this study is to evaluate the applicability of a seeded batch crystallization method as a pre‐treatment stage to the reduction of the the scaling potential of seawater. The crystallization process of calcium carbonate in supersaturated seawater is studied experimentally in a seeded batch crystallizer. Results show that the initial pH value of seawater must be adjusted to be in the range of 8‐9. Calcite seeds will not have the potential to start the growth process in seawater at he the normal pH (7.36) compared to the above mentioned range. The growth kinetic parameters are determined from the measured desupersaturation curves. It is found that the growth process of calcite is controlled by surface integration step. The growth rate of calcite increases with increasing temperature and seeding ratio (up to 1 g/L), while it decreases with increasing the salinity of seawater. Crystals of calcite morphology are found to be growing faster than seeds of aragonite morphology. Stirrer speed has no distinct effect on the growth rate of calcite in seawater. (© 2009 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Seeded crystallization of calcite and aragonite in seawater as a pretreatment scale control process, a study of supersaturation limits

The seeding crystallization of calcite and aragonite in seawater was evaluated theoretically and experimentally. The level of supersaturation with respect to calcium carbonate, which is the driving force for the crystal growth, was found to be influenced by the pH value of seawater, the temperature and the seed morphology. It was proven experimentally and theoretically that the level of supersaturation in seawater with respect to calcium carbonate is more sensitive to pH than to temperature. The growth process of calcite or aragonite cannot start if the pH value of seawater is not adjusted to be higher than 8.0 in the basic medium. An initial pH value of 8.2 is found to be enough to initiate the growth process of both calcite and aragonite seeds. Calcite seeds were found to be subjected to higher levels of supersaturation than aragonite.

Growth of nanofibrous barium carbonate on calcium carbonate seeds

Fibrous barium carbonate (BaCO 3/witherite) crystals 50–100 nm in diameter and several microns in length were grown on calcium carbonate (CaCO 3) seeds at temperatures as low as 4 °C. The BaCO 3 fibers were deposited onto calcite rhombs or CaCO 3 films using the polymer-induced liquid-precursor (PILP) process, which was induced with the sodium salt of polyacrylic acid (PAA). The structure and morphology of the resultant fibers were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and polarized light microscopy (PLM). Fibers were successfully grown on calcite seeds of various morphologies, with a range of barium concentrations, and PAA molecular weight and concentration. Two categories of fibers were grown: straight and twisted. Both types of fibers displayed single-crystalline SAED diffraction patterns, but after examining high-resolution TEM lattice images, it was revealed that the fibers were in fact made up of nanocrystalline domains. We postulate that these nanocrystalline domains are well aligned due to a singular nucleation event (i.e., each fiber propagates from a single nucleation event on the seed crystal) with the nanocrystalline domains resulting from stresses caused by dehydration during crystallization of the highly hydrated precursor phase. These BaCO 3 fibers grown on calcite substrates further illustrate the robustness and non-specificity of the PILP process.

Calcite-seeded crystallization of calcium phosphate for phosphorus recovery

For phosphorus recovery from wastewater, the present paper aims at understanding the crystallization of calcium phosphate by using calcites (Juraperle and Coccolith) as seeds from hard water. Synthetic hard water with 60 mg C l −1 carbonate and 10 mg P l −1 phosphate was prepared and used in the batch experiments of calcite-seeded crystallization. The solution composition was measured throughout the batch crystallization process, and the corresponding saturation indices with respect to the minerals were calculated with PHREEQC Program. The surface of the calcite seeds was observed and measured with environmental scanning electron microscopy (ESEM), Fourier transform infrared (FTIR) and BET method. The studies show that both calcites are effective seeds for the crystallization of calcium phosphate from hard water; the used calcites are more efficient than the original ones because newly formed crystals with calcium phosphate have covered their surfaces. The studies show that the calcite seeds can be used for phosphorus recovery from hard waters.

“Active filtration” for the elimination and recovery of phosphorus from waste water

A seed-induced crystallization process was developed to remove and recover phosphorus from waste water, i.e. attention has been especially drawn to gain a phosphorus-rich product, which can be recycled by the phosphorus industry and/or may directly be used as a fertilizer. The necessity of phosphorus recovery from phosphorus sinks is due to the fact that the world reserves of phosphorus rock will run out within the following 80–100 years. On the other hand, phosphorus is an essential nutrient for all forms of life, which cannot be replaced by any other element. For the development of this phosphorus recovery process, continuous-flow fixed-bed column and expanded-bed experiments were carried out in the laboratory scale using calcite (cc) and tobermorite-rich crushed gas concrete (cgc) as seeds. The experiments revealed that cgc was much more efficient in phosphorus removal from organic-enriched waste water compared to calcite seeds. Under suitable conditions, a phosphorus removal efficiency of 80–100% could be achieved for a time period of up to 4 months yielding a product containing about 10% P per weight. Furthermore, the physical and chemical properties of the product obtained proved the ability for phosphorus recovery. The results of FTIR and XRD investigations showed the transformation of cgc into calcite, the formation of hydroxyl apatite-like compounds on the seed material during the reaction with waste water, and finally the residual quartz originating from the cgc. A comparison of the results of laboratory- and half-scale fixed-bed column experiments revealed a shortened life-cycle of the columns with higher phosphorus concentrations of the inflow waste water, i.e. the velocity of Ca depletion within the fixed-bed system is governed by the P concentration. Active filtration using cgc seems a promising development for phosphorus removal and recovery from waste water. Thus, it should be possible in the near future to replace state-of-the-art methods of waste water treatment plants (WWTPs), such as metal precipitation or enhanced biological phosphorus removal (EBPR), which have the only aim of phosphorus removal, by a rather simple technology with the paramount goal of phosphorus recovery.