Colloidal Calcium Carbonate Research Articles

Efficient isolation of new lactobionic acid-producing microorganisms from environmental samples by colloidal calcium carbonate agar plate-based screening.

Lactobionic acid (LBA) has recently emerged as an important substance in various industries, such as cosmetics, foods, and pharmaceuticals. In this study, we developed a simple, efficient, and high-throughput method for screening LBA-producing microorganisms. First, an agar plate was prepared to isolate LBA-producing microorganisms by utilizing the property of LBA to solubilize colloidal calcium carbonate (CaCO3), resulting in the formation of a clear halo around colonies on a nutrient broth agar plate containing CaCO3. Subsequently, LBA production from the isolated microorganisms was confirmed using high-performance liquid chromatography (HPLC). Approximately 560 colonies from soil samples in Ulsan, Korea were screened and a clear halo was observed around three colonies on the prepared LBA-screening agar plate. The culture supernatants of these three colonies were analyzed by HPLC and it was found that these strains could produce LBA from lactose. Phylogenetic analysis by comparing their 16S rRNA nucleotide sequences revealed that these strains were Pseudomonas spp. and Alcaligenes faecalis. This is the first report highlighting that A. faecalis can produce LBA. As per the aforementioned results, the LBA-screening method that we devised here is highly effective for isolating and identifying new LBA-producing microorganisms.

Bioinspired selective synthesis of liquid-crystalline nanocomposites: formation of calcium carbonate-based composite nanodisks and nanorods.

Here we report new organic/inorganic hybrid colloidal liquid crystals that consist of colloidal calcium carbonate (CaCO3)/poly(acrylic acid) (PAA) hybrid nanodisks. We selectively synthesized anisotropic liquid-crystalline CaCO3-based nanodisk and nanorod composites in water/methanol mixtures, which formed discotic and calamitic nematic liquid crystals in their colloidal dispersions, respectively. The vaterite nanodisks and calcite nanorods were selectively synthesized in methanol-rich and water-rich solutions, respectively. The observation of these materials with transmission electron microscopy clarified the atomic-scale structures of these nanodisks and nanorods, revealing the self-organized CaCO3/PAA hybrid structures with the ability to form colloidal liquid crystals. The liquid crystals were prepared under mild and aqueous conditions by methods using acidic polymers inspired by the biomineralization process. The present approach provides new insights into the design of organic/inorganic hybrid colloidal liquid crystals and development of environmentally friendly functional hybrid materials.

Ultraviolet-curable polyurethane acrylate nanocomposite coatings based on surface-modified calcium carbonate

Abstract Polyurethane acrylate/surface-modified colloidal calcium carbonate (PUA/SCaCO3) nanocomposite coatings were successfully prepared via a UV-curing technology. The structural and morphological features of the PUA/SCaCO3 nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), and wide angle X-ray diffraction (XRD). The physical properties were strongly dependent upon chemical and morphological structures that originated from differences in SCaCO3 loading. A critical SCaCO3 concentration was observed for the evolution of both the structure and physical properties of the PUA/SCaCO3 nanocomposites as a function of SCaCO3 content. The thermal stability was measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively, and displayed some enhancement with the incorporation of SCaCO3 into PUA. Although the nanomechanical properties increased up to 3 wt% SCaCO3 content, they decreased due to lack of interfacial interaction with high SCaCO3 loading. Most importantly, the water uptake and water vapor transmission rate (WVTR) varied from 5.51 to 1.78 wt% and 28.9 to 19.9 g/m2 day, respectively, exhibiting significant enhancement in water resistance. The results clearly reveal that the performance of UV-curable PUA/SCaCO3 nanocomposites is strongly dependent on organically-modified colloidal SCaCO3 nanoparticles.

炭酸カルシウム・ナノ粒子は作物の栄養状態を改善し耐虫性を高める

Nanoparticles and nanotechnology have been applied in agriculture, including for plant nutrition improvement, and pest control. Little research has been conducted on nano-calcium carbonate in plant protection and nutrition. In this study, we compared the effects of nano-calcium carbonate and colloidal calcium carbonate and found that nano-calcium carbonate treatments were better at increasing calcium content when sprayed on Tankan (Citrus tankan) leaves. Field tests on California red scale (Aonidiella aurantii) and Oriental fruit flies (Bactrocera dorsalis) both showed that nano-calcium yielded better control rates. Moreover, bioassays of Oriental fruit flies conducted using calcium carbonate particles yielded lower LC50 values for nano-calcium. Additionally, nano-calcium performed better in terms of protection efficacy against oviposition punctures from Oriental fruit flies on the Indian jujube. Nano-calcium yielded better overall results than colloidal calcium for fertilization, plant protection, and pest control.

Residual stress behavior and physical properties of transparent polyimide/surface-modified CaCO3 nanocomposite films

A series of polyimide (PI) nanocomposite films with various surface-modified colloidal calcium carbonate (SCaCO3) contents were prepared and their physical properties were investigated to understand their possible use as polymer substrates. The morphology, thermal stability, residual stress behavior, moisture barrier and optical properties of nanocomposite films were investigated as a function of the SCaCO3 content and were found to be strongly dependent upon the chemical and morphological structures. With the addition of up to 0.5 wt% SCaCO3 in the PI matrix, resultant nanocomposite films exhibit not only enhanced thermal properties, but also minimized residual stress and excellent optical properties, simultaneously. With increasing SCaCO3 content, the water vapor transmission rate (WVTR) is greatly decreased from 630.76 to 484.22 g/m2/day. The residual stress was in the range of 26.0 to 12.1 MPa and is highly dependent on both temperature variation and SCaCO3 content. Although the residual stress becomes lower at 0.5 wt% SCaCO3 content, it increases at relatively high SCaCO3 loadings due to inadequate dispersion of the SCaCO3 and low interfacial interactions between the polymer and filler surfaces. Therefore, further studies are needed to maximize the performance of nanocomposite films by enhancing the compatibility of the polymer matrix and fillers.

Structure of Strongly Alkaline Alkyl Salicylate Additives

We have studied the structure and composition of strongly alkaline alkyl salicylate Detersol-300 and complex Kompleksal-250 additives. Potentiometric titration, chromatography, IR-spectroscopy, and X-ray diffraction were used to study the effect of the components of Detersol-300 and Komplaksal-250 on the structure of these additives. The micelles of the alkyl salicylate additives consist of spherical cores containing colloidal calcium carbonate completely coated with an adsorption shell of alkyl salicylate (sulfonate). Calcium carbonate has a vaterite structure, which does not change during synthesis of the complex salicylate/sulfonate additive Kompleksal-250.

Wall function model for particulate fouling applying XDLVO theory

A computational fluid dynamics (CFD) model for particulate fouling in heat exchangers has been developed. Particulate fouling is generally considered as a serial process of the transport of the particles into the vicinity of the wall and the adherence on the surface. Particle adhesion on the surface is described by a mass transfer coefficient based on the XDLVO theory. For modelling particle transport, the generally accepted models were applied. A wall function approach was developed for calculating the near-wall particle transport in order to avoid the use of excessively small computational cells. The model is based on the assumption of local equilibrium of the forces affecting the particle transport. The wall function model is compared to a detailed CFD model and to experimental results from a fouling test apparatus using the assumption of a smooth and already fouled surface. Comparisons were made with several heat fluxes and mass flow rates applying various high concentrations of colloidal calcium carbonate (CaCO3) particles suspended in water. Results of simulations are in fairly good agreement with measurements. The wall function model allows the applications of coarser computational grids and therefore modelling of practical industrial heat exchangers.

Effect of the particle size on the viscoelastic properties of filled polyethylene

Composites of surface treated and non-treated colloidal calcium carbonate and high-density polyethylene with different filler loading were prepared. Their viscoelastic properties were studied by dynamic strain sweep and small-amplitude oscillatory shear, and compared to those of the corresponding composites of micron-sized calcite. The specific surface area of the filler enormously increases as the average particle diameter becomes smaller than 600nm, leading to a strong tendency to agglomeration (soft flocks) and aggregation (hard clusters that need attrition to be disintegrated). In nanocomposites, more and stronger filler clusters are formed than in microcomposites due to the large contact area between the particles. The clusters have different shapes and maximum packing than the nearly spherical primary particles, thus enhance the moduli and viscosity of the composites. The obtained results indicate that the higher moduli and viscosity of the nanocomposites is not a direct consequence of the particle size but is due to the presence of more agglomerates and aggregates. Clusters that are local structures and do not represent a space-filling filler network enhance the moduli in the low frequency region more than at high frequencies and increase the storage more than the loss modulus. The presence of strong local structures in the nanocomposites leads to weak log moduli–log frequency dependence in the low frequency (terminal) region. Polymer adsorption on the particles' surface results in a transient filler–polymer network and slow dynamics of the bound polymer, which contribute to the moduli of the complex fluid. The sum of all these factors leads to gradual increase in moduli and to a shift of the crossover frequency to lower values. Above a certain filler volume fraction, the composite responds as a viscoelastic solid (storage modulus>loss modulus over the whole frequency range and both moduli are frequency independent in the terminal zone of the log–log plot).

Crystallization of Calcium Carbonate Observed In-situ by Combined Small- and Wide-angle X-ray Scattering

The transformation of amorphous colloidal calcium carbonate into single microcrystals was observed in supersaturated solutions in situ. The observations are done by simultaneous time-resolved small-angle and wide-angle X-ray scattering experiments (TR-SAXS/WAXS) at a third generation synchrotron source. TR-SAXS/WAXS demonstrates that the particles generated by reaction of Ca2+ and CO32- ions are amorphous. The transformation of these amorphous CaCO3 particles proceeds via dissolution and subsequent heterogeneous nucleation of the crystalline modification on the walls of the quartz capillary containing the reacting mixture. The crystalline modifications thus generated could be identified. No solid−solid transition is observed. TR-SAXS/WAXS is therefore well-suited to follow the mineralization from aqueous solution in great detail.

Formation and Growth of Amorphous Colloidal CaCO3 Precursor Particles as Detected by Time-Resolved SAXS

Time-resolved synchrotron small-angle X-ray scattering (SAXS) studies were performed to investigate the unseeded formation and growth of colloidal calcium carbonate particles. Equimolar aqueous solutions of CaCl2·2H2O and Na2CO3 were rapidly mixed in a stopped-flow apparatus, and SAXS data were recorded using an image-intensified CCD detector. It is shown that SAXS allows studying those processes in situ, with a very good time resolution. It can provide unsurpassed real-time information about the particle size, shape, polydispersity, inner structure, and density. In these studies, well-defined, spherical CaCO3 particles with colloidal dimensions up to ca. 270 nm and a remarkable uniformity in size could be observed. After a short nucleation period, the number density of the growing spheres remains constant. From the evaluation of the absolute scattering intensities, the particle mass density could be determined to be ca. 1.62 g/cm3, which is considerably lower than the density of the crystalline modificat...

Structure of Ultrabasic Sulfonate Greases

The effect of different components on the structure of ultrabasic calcium sulfonate during formation of a complex system was investigated by potentiometric titration and IR spectroscopy. Colloidal calcium carbonate has a calcite structure in the initial simple ultrabasic calcium sulfonate, in the intermediate model systems containing calcium tetraborate or 12–hydroxystearate, and in the final ultrabasic calcium sulfonate, and this structure does not change on conversion of the simple sulfonate grease into a complex grease. Micelles of the complex ultrabasic sulfonate grease consist of nuclei containing colloidal calcium carbonate and tetraborate coated with a calcium sulfonate and 12–hydroxystearate adsorption shell.

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Low crystalline porous aggregates of hydroxyapatite (HAp) were prepared with colloidal calcium carbonate and phosphoric acid. Particle size and specific surface area of spherical HAp aggregates were controllable by two-step phosphoration with colloidal calcium carbonate and ammonium dihydrogenphosphate using low crystalline porous aggregates of HAp as seeds. The HAp aggregates after two-step phosphoration showed high crystallinity and thermal stability.

Preparation of Spherical Hydroxyapatite Using Colloidal Calcium Carbonate as Seed Crystal

Preparation of Spherical Hydroxyapatite Using Colloidal Calcium Carbonate as Seed Crystal

Particle Size Determination of (Functionalized) Colloidal Calcium Carbonate by Small Angle X-Ray Scattering—Relation with Antiwear Properties

Three different colloidal calcium carbonate additives were each functionalized with dithiodiglycolic acid in order to convert 10 percent of the calcium carbonate content into the appropriate calcium carboxylate salt. The generated sulfurized calcium salts are located inside the micellar cores. Investigation of colloidal size distribution using small-angle-X-ray scattering has shown that the reaction takes place inside each micelle without modification of the general shape, and without any aggregation phenomena. Evaluation of the antiwear properties of each modified or unmodified product in a four-ball test shows that a minimum particle size is required to obtain a significant antiwear effect.

Kinetics and interfacial interactions in the adhesion of colloidal calcium carbonate to glass in a packed-bed

The adhesion of colloidal particles of calcium carbonate flowing through a packed-bed of glass, at different ionic strengths of the aqueous solutions has been studied. The experimental results are compared with those predicted by the Levich–Smoluchowski kinetic model and discussed in terms of the interfacial contributions to the adhesion between the particles and the substrate. Both materials have a negative zeta potential ranging from −75 to −10 mV (glass) and from −30 to 0 mV (calcium carbonate) in the range of electrolyte (NaCl) concentration used (10 −4–0.5 M). Thus the electrostatic component of free energy of interaction of glass–calcium carbonate is always repulsive. The surface free energy components of the two surfaces were studied by contact angle measurements (glass) and thin-layer wicking method (calcium carbonate). Glass behaves as an electron-donor monopolar surface (Lewis sense, see the work of C.J. van Oss, Interfacial Forces in Aqueous Media, Marcel Dekker, New York, 1994) at the lowest NaCl concentrations, but manifests a slight dipolar character (electron-acceptor component around 1.7 mJ/m 2) at [NaCl]>0.1 M. Calcium carbonate surface is also strongly monopolar at the lowest concentrations but the electron-acceptor component of its surface free energy predominates over the electron-donor component at the NaCl concentration 0.5 M. The determination of the free energy changes associated to interactions between surfaces in aqueous media demonstrated that, for [NaCl]≤10 −2 M, the adhesion between calcium carbonate and glass is a more favourable process than the aggregation between calcium carbonate particles. The contrary occurs for higher NaCl concentrations, i.e., the interaction between calcium carbonate particles is the dominant process and a further deposition of aggregates on glass could be the mechanism for the adhesion phenomena. The stability factors determined from the Levich–Smoluchowski theory allow the kinetic description of the coagulation phenomena involved in the adhesion processes in terms of efficiency of collisions between the interacting surfaces.

Phosphosulfuration of Colloidal Calcium Carbonate—Evaluation of Antiwear and Extreme-Pressure Properties

Colloidal calcium carbonate conventionally used as detergent in lubricant, i.e., overbased calcium sulfonate, was functionalized by the product of the reaction of calcium hydroxide and tetraphosphorus decasulfide with water to yield a mineral calcium thiophosphate, or with isopropanol to yield an organic calcium dialkyl dithiophosphate. These two species are respectively comicelized with the initial calcium carbonate colloidal core. The colloidal nature of these products was confirmed and they were evaluated in a four-ball test and compared to the original nonfunctionalized colloidal additive. Both modified products exhibit improved extreme-pressure performances, while their antiwear properties compared to those of the original overbased substrate remain at least at the same level.

Scaling analysis of sediment equilibrium in aggregated colloidal suspensions

The equilibrium of aggregated colloidal suspensions under gravity is studied both theoretically and experimentally. Using a simplified model to describe the compaction of the gelled suspension, we show that the volume fraction of the particles needed to form a stable gel is not intrinsic to the physicochemical system but depends on the height of the sample, its aspect ratio, and the friction between the suspension and the cell wall. A scaling analysis is developed to predict the various regimes encountered and to calculate the variations of the equilibrium sediment height as a function of the volume fraction of the particles and the height, and width of the sample. Good agreement is found with systematic measurements performed on aqueous colloidal calcium carbonate suspensions.

Colloidal suspensions of calcium carbonate in soils and their likely significance in the formation of calcic horizons

Evidence is presented to demonstrate that colloidal suspensions of calcium carbonate can be produced in the laboratory from naturally occurring CaCO 3 (Upper Chalk) and from a range of calcic horizons (Typic Hapludalf, southern England; Calcixerollic Xerochrept, southern Iran; and Xerollic Calciorthid, lower Egypt). Calcium carbonate in these calcic horizons and associated k-fabrics is in the form of colloidal-sized platelets. Particle size and ability to remain in colloidal suspension were determined for unground and for “TEMA” ground samples. Particle composition was determined using X-ray diffraction, differential thermal analysis and from X-ray fluorescence spectra (XRF). Particle morphology was obtained using the scanning electron microscope (SEM). The spatial morphological patterns observed in the calcic horizons of the three soils consisted of silt-sized, calcite platelets linked together by discontinuous coatings of both single and aggregated clay-sized, calcite platelets. Thus, as calcium carbonate in the soils was shown to be in colloidal form, the spatial and morphological patterns observed at the submicroscopic scale are attributed to physical transport of colloidal complexes rich in calcium carbonate. On mobilization, these colloidal complexes will be transported through inter-, intra- and transpedal pores by movement of soil water and deposited on ped surfaces and as linings to pore walls. Transport of colloidal calcium carbonate and deposition from suspension onto ped and pore surfaces is considered to be enhanced by irrigation practices and by lateral throughflow of water, that is by periodic and discrete soil/water/gravity events.

Use of Polyphosphates for Developing Protective Calcite Coatings

Success attained in work with synthetic recirculated water with a low ME of calcium carbonate and containing colloidal calcium carbonate has suggested that a practical field method might be devised for developing permanent protective coatings in relatively short periods of time. In order to explore this possibility, studies were begun with a continuous flow of Michigan State University tap water. In a series of tests, the tap water flow was divided to feed sodium hydroxide and sodium carbonate to a bypassed portion. The high, 10.5 pH level in the bypassed flow resulted in the development of colloidal calcium carbonate in that line. Data and qualitative observations reported here show that a useful approach to the problem of the formation of protective calcium carbonate coatings in iron water mains has been developed. The experimental data lead to these conclusions: Michigan State University tap water develops hard, dense, calcite coatings on iron nipples within a few hours at velocities of 8.0‐13.5 fps and a momentary calcium carbonate excess of about 5 ppm. Momentary excesses as high as 60 ppm, with a flow velocity of 1.5 fps, develop similar coatings, an uncontrolled momentary excess of more than 30 ppm results in heavy deposits of loose calcite, which vary from fine to coarse grain; the addition of O.5‐1.5 ppm metaphosphate controls calcium carbonate precipitation and permits the use of momentary‐excess values as high as 100 ppm without encrustation of feed lines or piping. With a velocity of 3.0 fps, thin, translucent calcite coatings have been developed which have useful anticorrosion value; calcite coatings have been obtained with metaphosphate concentrations of 2.2 ppm and calcium levels as high as 1,500 ppm (as CaCO3); however, these coatings are not superior to those obtained at lower metaphosphate and calcium levels; the DFI and ME values have proved to be more useful for predicting carbonate deposition than Langelier's or Ryznar's indexes; microscopic examination of the coatings developed on sandblasted metal has shown imperfections and rusting in the translucent calcite coatings, it is believed that imperfections are at points of deep penetration by high‐velocity sand grains during sandblasting; and, better coatings were obtained in 2‐hr experiments at 3.0 fps than at 1.5 fps. In general, better coatings have resulted at high velocity than at low velocity, probably because of the decreased thickness of the laminar boundary film, more rapid mixing rate, and increased velocity distribution.