Calcium Carbonate Solution Research Articles

Comparison of calcium scaling in direct contact membrane distillation (DCMD) and nanofiltration (NF)

Calcium scaling is commonly encountered in membrane separation processes with a profound impact on permeate flux and energy efficiency of these processes. Direct contact membrane distillation (DCMD) and nanofiltration (NF) were selected to study calcium scaling impact on thermal and pressure driven membrane processes. Calcium sulfate (CaSO4) and calcium carbonate (CaCO3) solutions with salinity in the range from 3000 to 30,000 mg/L were used as the feed. All DCMD and NF tests were performed at identical feed temperature (i.e., 40 °C) and shear conditions (i.e., Re = 771 ± 28). The average size of CaSO4 and CaCO3 crystals formed in the DCMD system was larger and the scale was more porous than in the NF system. The permeate flux in NF system was impacted by both calcium scales regardless of the feed salinity, while only CaSO4 scale formed at low salinity affected the performance of DCMD system. Surface crystallization in NF systems is likely extended into the membrane pores, which lead to permanent reduction in membrane permeability. This study demonstrated that the impact of calcium scaling is affected by both feed salinity and separation driving force, and is much less severe in thermal than pressure driven membrane processes.

Characterization of Iron Removal Process Products from Atmospheric Lateritic Ore Leaching Solution by using 20 and 25% of Calcium Carbonate

AbstractElectric vehicles become the alternative to solve the climate change and global warming problems by providing a more eco-friendly and sustainable source of energy. As the demand for sustainable vehicles increased, the functionality of batteries become crucial. One of the important aspects inside the batteries is nickel. Nickel plays a big role in lithium-ion batteries by delivering greater amounts of energy density with a higher storage capacity, which means it provides bigger efficiency to the batteries. Yet, the attempt of optimizing nickel extraction remains a challenge. Therfore, nickel extraction process of lateritic ore with high efficiency is investigated by using hydrometellurgy process, specifically the iron removal process in atmospheric condition in mixed hydroxide precipitates (MHP) route.The reagent solution of (20% w/w and 25% w/w) calcium carbonate (CaCO3) at pH (1, 2, 3) were utilized as additive in this process. The precipitates resulted from PLS were characterized by x-ray diffraction (XRD) and Scanning Electron Microscopy - Energy Dispersive X-Ray (SEM–EDS), while the filtrates were investigated by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Analysis based on precipitates demonstrates that the acid neutralization process took place with a sufficient amount of iron in the precipitates with the least amount of nickel. In addition, all pH and concentration of precipitates qualitatively illustrate the same neutralization process involving calcium and sulfur. From the results of filtrate through ICP testing in this study, pH 1 for both 20% and 25% concentration provides the lowest recovery rate alongside the smallest ppm compare to pH 2 and 3; thus, the iron precipitates in the formation of iron sulfide and/or iron sulfate. Overall, the optimum parameter is 25% of calcium carbonate, pH 1, 90oC for 2 hours of agitation to reduce the amount of iron in the solution.

POSS-Functionalized Graphene Oxide/PVDF Electrospun Membranes for Complete Arsenic Removal Using Membrane Distillation.

This work demonstrates very high removal rates (below the detection limit of 0.045 ppb) of inorganic arsenic from water using electrospun polyvinylidene difluoride (PVDF) membranes enhanced by the addition of functionalized graphene oxide in membrane distillation. This shows potential for applications in the many parts of the world suffering from arsenic-contaminated groundwater. These membranes were enhanced by the addition of reduced graphene oxide functionalized with superhydrophobic polyhedral oligomeric silsesquioxane molecules (POSS-rGO) into the spinning solutions. The flux of the best-performing rGO-enhanced membrane (containing 2 wt % POSS-rGO) was 21.5% higher than that of the pure PVDF membrane and almost double that of a commercial polytetrafluoroethylene (PTFE) membrane after 24 h of testing, with rejection values exceeding 99.9%. Furthermore, the flux of this membrane was stable over 5 days (∼28 L m–2 h–1) of continuous testing and was more stable than those of the PTFE and control membranes when treating a concentrated fouling solution of calcium carbonate and iron(III) sulfate heptahydrate. It also achieved higher permeate quality in these conditions. The Young’s modulus and ultimate tensile strength of the best-performing membrane increased by 38 and 271%, respectively, compared to the pure polymer membrane, while both had similar porosities of ∼91%.

Effects of calcium on the structure of intestinal microbiota in ovariectomized rats

To study the effect of calcium content on bone mineral density and intestinal microbiota in ovariectomized rats. A total of 30 Wistar rats were randomly divided into 3 groups, namely the sham operation group, the model group and the calcium carbonate supplement group. Postmenopausal osteoporosis rats were established by ovariectomy(OVX). After the first week of modeling, each group was intragastric separately. The calcium carbonate solution was given to the calcium carbonate supplement group, and the same amount of sterile water was given to the other two groups. The animals were executed at the end of the 12 weeks. Left femur was taken and bone mineral density(BMD) was detected by dual-energy X-ray absorptiometry. The total DNA of fecal samples was aseptically extracted and the Illumina Miseq platform was to carry out high-throughput sequencing. Compared with the sham operation group, the body mass increment of rats in the model group was significantly increased, the level of BMD was significantly reduced(P<0. 05), the intestinal microbiota diversity was not significantly changed, the Firmicutes abundance was decreased, and the Bacteroidetes abundance was increased. Compared with the model group, the body mass increment of rats in the calcium carbonate supplementation group was significantly reduced and BMD was significantly increased(P<0. 05). There was no significant change in the intestinal microbiota diversity, Firmicutes were increased, and Bacteroidetes were decreased. Calcium supplementation can improve bone mineral density and inhibit the increase of body mass during the experiment period, and its mechanism may be related to regulating the structure of intestinal microbiota.

Silanized Silica-Encapsulated Calcium Carbonate@Natural Rubber Composites Prepared by One-Pot Reaction.

This article demonstrates the one-pot reaction, an efficient and environmentally friendly organic synthesis method, utilized to prepare the silanized silica-encapsulated calcium carbonate@natural rubber composites (SSC@NR), following first mixing the calcium carbonate (CaCO3) solution, silica (SiO2) sol solution and a small amount of Si-69 solution, to modify the surface of CaCO3 particles, and then wet mixing with natural rubber latex. The obtained silanized silica-encapsulated calcium carbonate (SSC) particles were tested by TGA, FTIR and XRD, to substantiate the effect of surface modification. Moreover, the effects of the amount of SSC on the Mooney viscosity, curing characteristics, physical and mechanical properties and dynamic mechanical properties of the SSC@NR were investigated. The results show that the surface of modified CaCO3 is effectively coated with SiO2 particles by means of physical and chemical combination, to achieve the effect of surface coating. When the optimum amount of SSC filler is 40 phr, the SSC can form better physical adsorption and chemical combination with the NR molecular chains and can be evenly dispersed in the rubber matrix, resulting in the conspicuous improvement of physical and mechanical properties, such as the tensile strength, tear strength, elongation at break and abrasion resistance. Meanwhile, the compound with SSC has preferable processability and dynamic mechanical properties.

Effect of water compounds on photo-disinfection efficacy of TiO2 NP-embedded cellulose acetate film in natural water

Abstract Photocatalysis disinfection has great potential for irrigation water disinfection to improve fresh produce safety. Titanium dioxide (TiO2) nanoparticle (NP)-embedded cellulose acetate (CA) film has shown effectiveness against Escherichia coli (E. coli) O157:H7 in water. The current study evaluated the effect of natural water compounds on the photo-disinfection efficacy of TiO2 NP-embedded CA film. Humic acid, calcium carbonate (CaCO3), and kaolin clay solutions were prepared at four concentrations, respectively. When concentration increased from 0 to 20 ml/L, inactivation of E. coli O157:H7 in humic acid, CaCO3, and kaolin clay solutions decreased from 6 log to 5, 4, and 2 log CFU/ml, respectively after 3 h treatment. Turbidity, UVT-254, water hardness, total suspended solids (TSS), and total organic carbon (TOC) of the solutions were measured. UVT-254 and turbidity had the highest correlation with the inhibition effect of water compounds on photo-disinfection efficacy. A prediction equation was developed with UVT-254 and water hardness as independent variables to predict photo-disinfection efficacy in natural water. E. coli O157:H7 decreased by 1 and 2.5 log CFU/ml in unfiltered and filtered natural creek water samples after treatment. The results from this study showed promise in the use of TiO2 NP-embedded CA film to inactivate pathogens in natural water.

Resilient Intracrystalline Occlusions: A Solid-State NMR View of Local Structure as It Tunes Bulk Lattice Properties.

In many marine organisms, biomineralization—the crystallization of calcium-based ionic lattices—demonstrates how regulated processes optimize for diverse functions, often via incorporation of agents from the precipitation medium. We study a model system consisting of l-aspartic acid (Asp) which when added to the precipitation solution of calcium carbonate crystallizes the thermodynamically disfavored polymorph vaterite. Though vaterite is at best only kinetically stable, that stability is tunable, as vaterite grown with Asp at high concentration is both thermally and temporally stable, while vaterite grown at 10-fold lower Asp concentration, yet 2-fold less in the crystal, spontaneously transforms to calcite. Solid-state NMR shows that Asp is sparsely occluded within vaterite and calcite. CP-REDOR NMR reveals that each Asp is embedded in a perturbed occlusion shell of ∼8 disordered carbonates which bridge to the bulk. In both the as-deposited vaterites and the evolved calcite, the perturbed shell contains two sets of carbonate species distinguished by their proximity to the amine and identifiable based on 13C chemical shifts. The embedding shell and the occluded Asp act as an integral until which minimally rearranges even as the bulk undergoes extensive reorganization. The resilience of these occlusion units suggests that large Asp-free domains drive the vaterite to calcite transformation—which are retarded by the occlusion units, resulting in concentration-dependent lattice stability. Understanding the structure and properties of the occlusion unit, uniquely amenable to ssNMR, thus appears to be a key to explaining other macroscopic properties, such as hardness.

Amino Acid and Oligopeptide Effects on Calcium Carbonate Solutions.

Biological organisms display sophisticated control of nucleation and crystallization of minerals. In order to mimic living systems, deciphering the mechanisms by which organic molecules control the formation of mineral phases from solution is a key step. We have used computer simulations to investigate the effects of the amino acids arginine, aspartic acid, and glycine on species that form in solutions of calcium carbonate (CaCO3) at lower and higher levels of supersaturation. This provides net positive, negative, and neutral additives. In addition, we have prepared simulations containing hexapeptides of the amino acids to consider the effect of additive size on the solution species. We find that additives have limited impact on the formation of extended, liquid-like CaCO3 networks in supersaturated solutions. Additives control the amount of (bi)carbonate in solution, but more importantly, they are able to stabilize these networks on the time scales of the simulations. This is achieved by coordinating the networks and assembled additive clusters in solutions. The association leads to subtle changes in the coordination of CaCO3 and reduced mobility of the cations. We find that the number of solute association sites and the size and topology of the additives are more important than their net charge. Our results help to understand why polymer additives are so effective at stabilizing dense liquid CaCO3 phases.

Ion Pairing and Multiple Ion Binding in Calcium Carbonate Solutions Based on a Polarizable AMOEBA Force Field and Ab Initio Molecular Dynamics.

The speciation of calcium carbonate in water is important to the geochemistry of the world's oceans and has ignited significant debate regarding the mechanism by which nucleation occurs. Here, it is vital to be able to quantify the thermodynamics of ion pairing versus higher order association processes in order to distinguish between possible pathways. Given that it is experimentally challenging to quantify such species, here we determine the thermodynamics for ion pairing and multiple binding of calcium carbonate species using bias-enhanced molecular dynamics. In order to examine the uncertainties underlying these results, we derived a new polarizable force field for both calcium carbonate and bicarbonate in water based on the AMOEBA model to compare against our earlier rigid ion model, both of which are further benchmarked against ab initio molecular dynamics for the ion pair. Both force fields consistently indicate that the association of calcium carbonate ion pairs to form larger species is stable, though with an equilibrium constant that is lower than for ion pairing itself.

Optimizing Extraction of Proteins from Carcinus Maenus After Removal of Low‐Molecular Weight Chitins

Crab shells as waste products are presently of economic interest only for the value of the chitin polymer present in their shells, which may be used to formulate foods or pharmaceutical products. Other materials in the crab shells, including protein, are discarded as waste. Crab shells have a large protein content A key question to examine is if there are bioactive proteins and/or peptides that have health benefits which could be recovered and utilized as a value added fraction from the waste stream. For example proteins isolated from crab shells have been found to contain antimicrobial and moderate antitumor agents (Sawssen, 2015.)In this work, the procedures used for removal of low molecular weight (LMW) chitin were followed (Ye, 2016). After removal of LMW chitin, the acetic acid extraction of proteins from crab shells was optimized using 50%, 25% and 12% acetic acid. One of the challenges associated with the extraction of proteins from crab shells is the concomitant demineralization of the shells which results in a high calcium carbonate solution in solution. In this project, a variety of different methods for separating the protein from the acidic solution and the calcium carbonate were utilized including dialysis, polyethylene glycol precipitation strategies.These findings will be of value to the community of researchers investigating either bioactive materials in the shells of marine organisms.

Phase relations in the calcium carbonate/ammonium phosphate system under aqueous conditions and 25°C

AbstractA theoretical and experimental approach was applied to investigate phase relations in a system containing calcium carbonate and different ammonium phosphate solutions. Using laboratory experiments and thermodynamic modeling, this paper provides an insight into the formation of stable phase assemblages in the calcium carbonate and mono‐, di‐, triammonium phosphate aqueous system. Focus is placed on the morphological and mineralogical characterization and thermodynamic calculation of calcium phosphates precipitating due to the reaction between the calcium carbonate and ammonium phosphate solutions. Correlations between the formed stable calcium phosphate phases and the ammonium phosphate precursors are provided. Advantages and limitations of various analytical and modeling techniques used in this study such as geochemical equilibrium‐based modeling, X‐ray diffraction, scanning electron microscopy, and thermal analysis, are critically evaluated. Additionally, possible impacts of the ammonium phosphate solution type on the kinetics of phase transformations are discussed.

Mineral Filling Pattern in Complex Fracture System of Carbonate Reservoirs: Implications from Geochemical Modeling of Water-Rock Interaction

Much research has been conducted on physical and numerical modeling that focus on stress state and structural controls on subsurface geofluid flow, yet very few attempts have been made to discover and quantify the mineral precipitation/dissolution kinetics in complex fracture system such as Tarim Basin of China. We conducted a geochemical simulation study using the outcrop fracture networks in Ordovician carbonate rocks in Tabei Outcrop Area of Tarim Basin. Structural analysis, filling analysis within the fracture networks and surrounding rocks were used to constrain the generation and geochemical evolution of the geofluids. Using an advanced reactive transport simulation platform TOUGHREACT, a pertinent thermodynamic system was applied to establish the geological model of the fracture-surrounding rock, where the corresponding calcium carbonate (CaCO3) solution was configured to replace the deep saturated hydrothermal fluids. Different types of mineral parameters were considered with material balance and phase equilibrium calculation to perform numerical simulation of multi-field, e.g., pressure field, temperature field, seepage field and chemical field under formation conditions. The simulation results were consistent with field observations. The major findings of this simulation study include: (1) Along with fluid injection, local dissolution occurred within the fractures and matrix, but with the gradual saturation of calcium ions and the increasing pH value, considerable calcite precipitation occurred. (2) The dissolution/precipitation in different fractures was mainly affected by their structure and physical properties, resulting in changes in fluid flow rate, temperature, pressure and ion concentration over time. (3) In the same group, the degree of mineral filling of small-aperture fractures, low-angle fractures and shallow fractures was significantly higher than other types of fractures. (4) The better the connectivity between reticular fractures and the higher the linear density of fractures, the lower the mineral filling degree. (5) Dissolution phenomenon strengthened within large-aperture conjugated fractures gradually along the flow direction. The proposed methodologies in this study can be applied to model effective fracture filling of other deep reservoirs.

EFFECT OF WATER QUANTITY AND FOLIAR SPRAY WITH SOME SAFELY SUBSTANCES ON GROWTH, YIELD QUALITY AND STORABILITY OF GARLIC 1- GROWTH, YIELD, WATER RELATIONS AND LEAF PIGMENTS

Two field experiments were carried out during two successive winter seasons of 2015-2016 and 2016-2017 at the Experimental Farm, El Kassasein Horticultural Research Station, Ismailia Governorate, to clarify the effects of different rates of irrigation water; i.e., 1300, 1950 and 2600 m3/ fed. and foliar spray with some safely substances; i.e., potassium chloride, algae extract, potassium humate and calcium carbonate in addition to control treatment on growth, bulb quality, yield, water relations as well as leaf pigments and proline amino acid content of garlic plants (Allium sativum L.) cv. Chinese, grown under sandy soil conditions using drip irrigation system. Irrigation water quantity at 2600 or 1950 m3/ fed. were the superior treatments which significantly increased vegetative growth characters, bulb physical characters, total water, free water, water utilization and total yield without significant differences between them in most cases. Meanwhile, chlorophylls, bound water, water economy and proline amino acid content were at their maximum values under water stress (1300 m3/ fed.). Aqueous solution of calcium carbonate at 6% and/ or potassium humate at 0.2% as foliar spray had significant effect, in most cases, on plant growth, bulb physical characters, free water, water economy and total yield without significant differences between them. The interaction between calcium carbonate at 6% and/ or potassium humate at 0.2% and irrigation water quantity at 1950 m3/ fed. enhanced plant growth, bulb physical characters, total water, free water, water economy and total yield.

EFFECT OF WATER QUANTITY AND FOLIAR SPRAY WITH SOME SAFELY SUBSTANCES ON GROWTH, YIELD QUALITY AND STORABILITY OF GARLIC 2- STORABILITY AND VOLATILE OIL PERCENTAGE

Two field experiments were carried out during two successive winter seasons of 2015-2016 and 2016-2017 at the Experimental Farm, El Kassasein Horticultural Research Station, Ismailia Governorate, to clarify the effects of different rates of irrigation water ,i.e.( 1300, 1950 and 2600 m3/ fed.) and foliar spray with some safely substances ,i.e.( Potassium chloride at 1% ,Algae extract at 0.3%, Potassium humate at 0.2%, Calcium carbonate at 6% and control treatment) on volatile oil percentage and oil yield per plant of garlic plants (Allium sativum L.) cv. Chinese, grown under sandy soil conditions using drip irrigation system. This work aimed also to study the effect of the abovementioned treatments on garlic plants during storage at different periods; i.e., 40, 80, 120, 160 and 200 up to 320 days. Irrigation water quantity at 2600 or 1950 m3/ fed. were the superior treatments which significantly increased volatile oil percentage and oil yield per plant. Aqueous solution of calcium carbonate at 6% and/ or potassium humate at 0.2% as foliar spray had a promotive effect, on volatile oil percentage and oil yield per plant. The interaction between calcium carbonate at 6% and/ or potassium humate at 0.2% and irrigation water quantity at 2600 or 1950 m3/ fed. enhanced volatile oil percentage and oil yield per plant. Regarding storage experiment, the obtained results showed that there were a considerable and a continuous increase in weight loss and sprouting % as the storage period was extended, while TSS% was increased by increasing storage period. Increasing irrigation water up to 2600 m3/fed. significantly increased weight loss and sprouting %, while TSS% was decreased. Foliar application with calcium carbonate at 6% and/ or potassium humate at 0.2% were the superior treatments for increasing TSS% and decreasing weight loss and sprouting percentage. As for the triple interaction treatments, the beast values of weight loss, sprouting and TSS% at the end of storage period were noticed by irrigation with1300 m3/fed. and foliar spray with CaCo3 and/or potassium humate followed by irrigation with 1950 m3/fed. with the same foliar application solutions

Molecular Dynamics Simulation on Aqueous Solution of Calcium Carbonate System

Molecular dynamics simulation was used to investigate two models of aqueous solution ofcalcium carbonate system between 283K and 373K. The diffusion coefficients of water moleculesdemonstrated that both the electropositive surface (110) on Model-I and neutral surface (104) onModel-II showed interaction with the water molecules, and the surface (110) exhibited strongerelectrostatic interaction with water molecules than the latter, besides obvious anomaly appeared near343K on Model-I. On the other hand, surface (110) exhibited anomalous influences on Ca2+ andCO32- ions near 313K and 343K on Model-I, and only a broad anomaly on CO32- ions near 343K onModel-II. The binding energies between surface (110) / (104) and Ca2+ /CO32- ions demonstrated thatthe surface (104)were more favorable for the growth of the new crystal but weak for the diffusion.

Coral calcification, mucus, and the origin of skeletal organic molecules

Biocalcification encompasses the kinetic and structural, abiotic and biologically mediated processes involved in the formation of calcium carbonate skeletons by marine organisms and represents a key process in the global carbon cycle. Throughout the geological record, this process has evolved repetitively and has altered global biogeochemical cycles. Besides the structural variability of calcium carbonate polymorphs laid down by different organisms, biogenic carbonate skeletons are characterized by the presence of organic molecules that are incorporated into the growing skeleton. Major advances have identified the macromolecules associated to the organic matrix within marine calcifiers, however, it has yet to be established the actual role these organic molecules play in the calcification process. In this study, we isolated the effect of skeletal organic molecules (SOM) on the precipitation of calcium carbonate on coral skeleton fragments by adding extracted SOM or coral mucus (CM) to oversaturated calcium carbonate solutions. We found that the precipitation rate did not change regardless if organic molecules were present or not. However, the primary polymorph did change between the treatments, suggesting that organic molecules influence the surface processes that lead to the formation of the crystal lattice but not the kinetic processes that transport ions to the crystal surface. Since SOM and CM both altered the crystal polymorph but not the crystallization rate, we argue that SOM may not represent a specialized biomineralization toolkit, but that SOM originate from CM and the requirement of the polyp to adhere to the substratum.

Precipitation of Calcium Carbonate (CaCO3) in Water–Monoethylene Glycol Solutions

The influence of monoethylene glycol (MEG) on the precipitation process of calcium carbonate at constant supersaturation, 25 °C, and pH 8.5 was investigated. MEG aqueous solutions supersaturated with respect to all calcium carbonate polymorphs were used since they are often encountered in oil production processes where they are used as a hydrate inhibitor. Both seeded and unseeded experiments were done in aqueous supersaturated calcium carbonate solutions containing MEG over the concentration range 0–80% v/v. The presence of MEG affected the induction times and the subsequent rates of precipitation in unseeded, spontaneous precipitation of calcium carbonate. At low values of the supersaturation ratio (SRcalcite = 77.62–15 135.61 or σcalcite = 7.81–122) and for MEG concentrations in the range 30–80% v/v, the solutions were stable for 4 days. At lower than 30% v/v MEG concentrations, calcium carbonate precipitation took place past induction periods between 160 and 500 min. The morphological examination of the precipitates showed that in the presence of low MEG concentrations (10–20% v/v) the precursor vaterite was stabilized. The homogeneous nucleation and growth of calcium carbonate in the absence and in the presence of MEG was also investigated by the inoculation of stable supersaturated solutions with quartz and calcite seed crystals. In both cases nucleation and growth of calcium carbonate was significantly reduced with increasing MEG concentration in the solutions.

Reference materials selection for the stable carbon isotope analysis of dissolved carbon using a wet oxidation system.

Wet chemical oxidation combined with isotope ratio mass spectrometry has become a routine technique for analyzing the stable carbon isotope composition of dissolved organic (DOC) and inorganic (DIC) carbon. However, methodological inconsistencies between laboratories in using different reference materials lead to a discrepancy in results. We experimentally tested the precision and accuracy of the analysis of commonly available international reference materials and other chemicals potentially suitable for laboratory standards. The solid international reference materials and other simple chemicals were used to prepare water solutions. A range of carbon concentrations was chosen to optimize tests for (1) precision and accuracy, (2) linearity, (3) detection limits, (4) memory effects, and (5) efficiency of DIC removal from a DOC/DIC mixtures. Samples were analyzed using an LC-IsoLink coupled with a Delta V Plus isotope ratio mass spectrometer (Thermo Fisher Scientific). The analytical setup had a negligible memory effect, good reproducibility (<0.21‰) and accuracy (maximum difference from the true values <0.35‰) for the analyzed organic compounds if approximately ≥9 × 10-09 moles of dissolved carbon was injected into the system (~11 mg C L-1 if a 10-μL loop was used). Analyses of sodium bicarbonate or calcium carbonate solutions had a two-fold lower accuracy despite maintaining a high precision. Aqueous solutions of international reference materials such as L-glutamic acids (USGS40, USGS41), benzoic acid (IAEA-601) and sucrose (IAEA-CH-6) can be successfully used for direct normalization of results to the VPDB scale. By contrast, analyses of caffeine and urea returned very reproducible but highly inaccurate results and these materials are not recommended for standards.

Oil majors invest in CO2 capture company

Venture investment arms of Chevron and Occidental Petroleum have invested an undisclosed sum in Carbon Engineering, a Canadian firm that is developing a chemical method of capturing CO2 from the atmosphere. In the process, CO2 reacts with calcium hydroxide to create a calcium carbonate solution. Carbonate pellets are formed, then decomposed into concentrated CO2 and solid calcium oxide. The CaO is then hydrated to regenerate the hydroxide. Carbon Engineering raised about $8 million in July.

PHOTOCATALYTIC ACTIVITY UNDER VISIBLE LIGHT REGION OF Ca-MODIFIED TiO2NP FILMS PREPARED BY SPARKING OFF Ca-ELECTROPLATED Ti TIPS

In this work, calcium (Ca)-modified titanium dioxide (TiO2) nanoparticulate (NP) films were successfully prepared using sparking off Ca-electroplated Ti tips. Aqueous solution of calcium carbonate (CaCO3) was used as electrolyte in the electroplating process. The experiment was carried out using electric current of 0.02[Formula: see text]mA applied to titanium electrodes for 10[Formula: see text]min. The NP films with small and uniform size were deposited on quartz substrate using the sparking process with a high DC voltage of 4[Formula: see text]kV in ambient air. The as-deposited NP films were then annealed at 800∘C, 900∘C and 1000∘C for 3[Formula: see text]h under atmospheric pressure to improve their crystallinity. Morphology, structural and optical properties of the NP films were characterized by SEM, XRD, Raman, XPS and UV-Vis spectroscopy. The effects of annealing temperature on the properties of the as-deposited and annealed NP films were reported. Furthermore, photocatalytic activity against 10 [Formula: see text]M of methylene blue (MB) under visible light region will be discussed.