Solid Calcium Carbonate Research Articles

Preferential formation of uniform spherical vaterite by harnessing vortex flows and integrated CO2 capture and mineralization

The use of calcium bearing resources to facilitate solvent regeneration and CO2 reuse via carbon mineralization offers a low energy pathway for the production of calcium carbonate. However, a crucial challenge is the lack of specificity in the formation of various calcium carbonate polymorphs during carbon mineralization. One of the less explored but highly effective approaches to tune the morphology and crystal structure of specific carbonate phases involves tuning vortex flows. This approach is an alternative to utilizing chemical reagents that need to be regenerated for tuning the morphologies and crystalline structures to direct the formation of specific carbonate phases. In this study, the efficacy of using homogeneous vortex flows in limiting the agglomeration of carbonate particles and directing the formation of metastable vaterite phases is discussed and contrasted with the influence of inhomogeneous conventional feed flow patterns on precipitated calcium carbonate (PCC). Herein, a Taylor-Couette Carbonate Conversion (TC3) reactor is used to direct the formation of spherical vaterite particles with uniform particle size distribution preferentially over calcite and other phases. The formed vortex patterns inside TC3 reactor provide homogeneous reaction spaces conducive to PCC formation, ensuring uniform mixing throughout the process. By increasing the rotational speed and the residence time, higher purity carbonates with more uniform sizes are obtained. Furthermore, preferential vaterite formation is also observed in leachates obtained from alkaline industrial residues such as construction and demolition waste and steel slag. Thus, the proposed approach is effective in harnessing multiple waste streams such as CO2 emissions and alkaline industrial residues to produce calcium carbonate phases such as vaterite with structural and morphological specificity.

Solid CaCO3 Formation in Glioblastoma Multiforme and its Treatment with Ultra-Nanoparticulated NPt-Bionanocatalysts.

Glioblastoma multiforme (GBM), the most prevalent form of central nervous system (CNS) cancer, stands as a highly aggressive glioma deemed virtually incurable according to the World Health Organization (WHO) standards, with survival rates typically falling between 6 to 18 months. Despite concerted efforts, advancements in survival rates have been elusive. Recent cutting-edge research has unveiled bionanocatalysts with 1% Pt, demonstrating unparalleled selectivity in cleaving C-C, C-N, and C-O bonds within DNA in malignant cells. The application of these nanoparticles has yielded promising outcomes. The objective of this study is to employ bionanocatalysts for the treatment of Glioblastoma Multiforme (GBM) in a patient, followed by the evaluation of obtained tissues through electronic microscopy. Bionanocatalysts were synthesized using established protocols. These catalysts were then surgically implanted into the GBM tissue through stereotaxic procedures. Subsequently, tissue samples were extracted from the patient and meticulously examined using Scanning Electron Microscopy (SEM). Detailed examination of biopsies via SEM unveiled a complex network of small capillaries branching from a central vessel, accompanied by a significant presence of solid carbonate formations. Remarkably, the patient subjected to this innovative approach exhibited a three-year extension in survival, highlighting the potential efficacy of bionanocatalysts in combating GBM and its metastases. Bionanocatalysts demonstrate promise as a viable treatment option for severe cases of GBM. Additionally, the identification of solid calcium carbonate formations may serve as a diagnostic marker not only for GBM but also for other CNS pathologies.

Enhancing performance and sustainability of ultra-high-performance concrete through solid calcium carbonate precipitation.

Ultra-high-performance concrete (UHPC) exhibits high compressive strength and good durability. However, owing to the dense microstructure of UHPC, carbonation curing cannot be performed to capture and sequester carbon dioxide (CO2). In this study, CO2 was added to UHPC indirectly. Gaseous CO2 was first converted into solid calcium carbonate (CaCO3) using calcium hydroxide, and the converted CaCO3 was then added to UHPC at 2, 4, and 6 wt% based on the cementitious material. The performance and sustainability of UHPC with indirect CO2 addition were investigated through macroscopic and microscopic experiments. The experimental results showed that the method used did not negatively affect the performance of UHPC. Compared with the control group, the early strength, ultrasonic velocity, and resistivity of UHPC containing solid CO2 improved to varying degrees. Microscopic experiments, such as heat of hydration and thermogravimetric analysis (TGA), demonstrated that adding captured CO2 accelerated the hydration rate of the paste. Finally, the CO2 emissions were normalized according to the compressive strength and resistivity at 28 days. The results indicated that the CO2 emissions per unit compressive strength and unit resistivity of UHPC with CO2 were lower than those of the control group.

REPORT ON FUNGI ASSOCIATED WITH CORAL SKELETON FROM SAINT MARTIN'S ISLAND, BANGLADESH

A total of 9 fungal species belonging to four genera were found to be associated with coral skeleton collected from Saint Mar tin’s Island, Bangladesh. The isolated fungi were Arthrinium Kunze, Aspergillus flavus Link, Fusarium nivale (Fr.) Sorauer, F. oxysporum Schltdl., F. sambucinum Fuckel, F. semitectum Berk. & Ravenel, F. stoveri Booth, F. trichothecioides Wollenw and Penicillium Link. The genus Fusarium was predominant among the associated fungi. This is the first report of fungal association with solid calcium carbonate substrate like coral skeleton from Bangladesh. Fusarium sambucinum and F. stoveri are first time recorded from Bangladesh. Bioresearch Commu. 9(1): 1203-1207, 2023 (January)

Novel regimes of calcium carbonate dissolution in micron-scale confined spaces

We report the discovery of novel regimes of calcium carbonate dissolution in micron-scale confined spaces through microfluidic experiments. In the experiments, hydrochloric acid is injected into a microfluidic chamber with pre-deposited calcium carbonate solids. As the acid flow rate is decreased, the dissolution of calcium carbonate transits from a liquid/solid single-phase reactive transport regime to a gas/liquid/solid two-phase one. The two-phase regime further splits into two different regimes, one with fluctuating and the other with nonfluctuating gaseous CO2 phase. We name the three regimes as “Nongaseous”, “Gaseous Breathing”, and “Gaseous Nonbreathing”. The experimental observations are reproduced and interpreted by mathematical modeling. Results show that the regimes are controlled by the ratio of H+ concentration and saturated CO2 concentration, the Peclet number and the second Damkohler number. Dimensionless diagrams distinguishing different regimes are presented and an empirical relationship is proposed. Our results offer insights into various engineering and natural processes, e.g., geological carbon storage, petroleum reservoir acidizing, Karst dissolution, and others that are governed by small scale multiphase reactive flow physics.

아연 이온화 장치에 의한 물 중 탄산칼슘 스케일 생성 억제 및 제거 효과 측정

Scale inhibition effect of the physical water treatment device that emits zinc cation in water was evaluated. The inhibition effect of scale formation was confirmed by the difference in precipitation amount of calcium carbonate prepared from calcium chloride and sodium carbonate solution with distilled or zinc ionized water. For measuring removal effect of solid calcium carbonate on the filter paper, the ground water passed through the ionizer or not was poured on the filter paper and the differences of weight loss of solid CaCO₃ were observed. In the experiments for inhibition, the addition of zinc ion did not appear to change the amount of calcium carbonate precipitate. On the other hand, zinc ion leaving the filter clumped fine calcium carbonate particles to increase turbidity, and it was estimated that scale particles expected to have grown by zinc ions were discharged by water flow. Although the concentration of zinc ions from the ionization device is only tens of ㎍/L, the exposure of zinc ions for a long period of time was expected to slowly release the scale generated on the inside wall of the pipe.

Insight into the high-efficiency adsorption of pyrene by Schiff base porous polymers: Modelling and mechanism

Pyrene (PYR) as one of polycyclic aromatic hydrocarbons (PAHs) has attracted increasing attention due to their carcinogenicity, mutagenicity and toxicity. A novel Schiff base porous organic nanocomposite is successfully synthesized via the encapsulating and etching processes. Nano-scale calcium carbonate was used as the solid core in Schiff base derived by condensation of 1, 4-Diaminobenzene and Benzene-1, 4-dicarboxaldehyde. After that, the solid state calcium carbonate was etched by low concentration hydrochloric acid. Finally, Schiff base polymer with porous structure was obtained through filtration, rinsing and drying. XRD, SEM, BET, XPS, Raman, FTIR and TGA technologies were used to characterize the samples. As expected, the novel Schiff base porous organic polymer (SBPP-0.5) exhibited excellent adsorption capacity for PYR. Based on adsorption isotherms and kinetics investigation, PYR adsorption on Schiff base porous organic polymer is mainly affected by chemical interactions. The adsorption sites are uniform and the aromatic structure of planer PYR molecules could inevitably present intense π-π interactions with the aromatic nucleus of Schiff base porous organic polymer. The adsorption process is multi-stage and film diffusion dominated the adsorption process, which is mainly occurred in the initial adsorption stage. This work shows that Schiff base polymer with complicated microstructure can be used for PAHs removing.

Evaluating durability parameters of concrete containing limestone powder and slag under bacterial remediation

Microbiological methods, in which bacteria serve as catalysts and contribute to urea hydrolysis by producing the urease enzyme, can be used to enhance concrete durability and repair the entrained pores and micro-cracks. The hydrolysis of urea in a calcium-rich environment leads to the formation of solid calcium carbonate that fills concrete pores and cracks. At least 7% of the total carbon dioxide available on a global scale originates from cement production. This has encouraged efforts to decrease cement consumption in concrete structures and to replace it with such cement-like materials as fly ash, blast furnace slag, micro silica, or limestone powder. Slag and fine limestone have nowadays gained wide applications as cement replacements for their technical, economic, and environmental advantages. The present study was designed and implemented to investigate concrete durability, water absorption, carbonation depth, and water penetration depth in specimens containing slag and fine limestone powder in their concrete mixes, where exposed to the bacterial treatment. For this study, 78 concrete cubes of 100 mm in size, 78 cubes of 70 mm, and 78 prisms of 120 × 200 × 200 mm3 were made using six concrete mix designs containing two limestone powder ratios of 0 and 15% and three slag ratios of 0, 20, and 40% as replacements for cement. The specimens were subsequently treated for 28 days in one of the curing media of tap water, seawater, and a solution of calcium lactate and urea. Finally, the surfaces of the specimens were treated for two weeks in one of the above media. Results showed improved durability in both concrete specimens with bacteria in their mix designs and those subjected to surface treatment with bacteria. Moreover, all the specimens with bacteria recorded lower values of water absorption, carbonation, and water penetration depths than those lacking bacteria. As regards the cement replacement materials, it was found that limestone powder served as a source of calcium for bacteria and that slag enhanced the compressive strength of concrete and reduced its permeability. Finally, the solution of calcium lactate and urea from among the curing media investigated was found to have better effects on the specimens either containing bacteria in their mix designs or subjected to surface remediation with bacteria.

Effect of precipitation mineralization reactions on convective dissolution ofCO2: An experimental study

When CO${}_{2}$ dissolves in a solution of calcium ions, a precipitation mineralization reaction can take place, producing solid calcium carbonate particles that sink to the bottom of the host phase. Convective motions present both above and below the reaction front favor the entrainment of CO${}_{2}$ toward the bottom, which is favorable for the security of carbon sequestration techniques. An experimental study of the influence of such a precipitation reaction on convective dissolution of CO${}_{2}$ is conducted.

Research and Evaluation of a New Autogenic Acid System Suitable for Acid Fracturing of a High-Temperature Reservoir.

An organic ester p-nitrobenzyl acetate (PNBA) was synthesized and used to establish a kind of autogenic acid system through the hydrolysis of ester to acetic acid in situ. The autogenic acid system can form a homogeneous solution by adding an organic solvent. The autogenic acid system possesses the desired characteristic in which hydrolysis can generate a small amount of acetic acid below 120 °C and a large amount of acid above 140 °C in 2 h. The acid-generated ability at different time and temperature was studied in detail. The dissolution of solid calcium carbonate and carbonate rocks by the autogenic acid system was investigated. The autogenic acid displayed lower dissolution ability on a carbonate rock and weak corrosion of a N80 steel sheet at 150 °C. The autogenic acid is especially suitable for acid fracturing and dissolution of rocks in a high-temperature carbonate reservoir.

Estivation in the Apple Snail Pomacea maculata: Mobilization of Calcium Granules in the Lung

The effect of long-term estivation on the abundance of calcium granules in the lung tissue of the apple snail Pomacea maculata Perry was studied. Electron-dispersive spectrophotometric analysis of the shell and the granular inclusions in the lung show that both structures are composed of calcium carbonate. The layers forming the shell are similar to those found in the shells of other gastropods. Calcium granules are extremely abundant in the tissues of the lung of P. maculata. The spherical granules consist of concentric layers of material inside calcium cells. There are three distinct populations of hemocytes in P. maculata hemolymph, two cell types with granulocytic morphology and one agranular type. Selective staining shows that hemocytes contain large amounts of calcium, implicating these cells in the transport of calcium carbonate from storage sites to other tissues. The pCO2 of the hemolymph increases in estivating gastropods, and it has been suggested that stores of solid calcium carbonate are mobilized to buffer the resulting acidity. Results of this study show that a large decrease in the abundance of calcium carbonate granules in the lung tissue occurs during estivation. In addition, there is evidence that a calcium binding protein is present in the hemocytes.

Confining Iron Oxide Nanocubes inside Submicrometric Cavities as a Key Strategy To Preserve Magnetic Heat Losses in an Intracellular Environment.

The design of magnetic nanostructures whose magnetic heating efficiency remains unaffected at the tumor site is a fundamental requirement to further advance magnetic hyperthermia in the clinic. This work demonstrates that the confinement of magnetic nanoparticles (NPs) into a sub-micrometer cavity is a key strategy to enable a certain degree of nanoparticle motion and minimize aggregation effects, consequently preserving the magnetic heat loss of iron oxide nanocubes (IONCs) under different conditions, including intracellular environments. We fabricated magnetic layer-by-layer (LbL) self-assembled polyelectrolyte sub-micrometer capsules using three different approaches, and we studied their heating efficiency as obtained in aqueous dispersions and after internalization by tumor cells. First, IONCs were added to the hollow cavities of LbL submicrocapsules, allowing the IONCs to move to a certain extent in the capsule cavities. Second, IONCs were coencapsulated into solid calcium carbonate cores coated with LbL polymer shells. Third, IONCs were incorporated within the polymer layers of the LbL capsule walls. In aqueous solution, higher specific absorption rate (SAR) values were related to those of free IONCs, while lower SAR values were recorded for capsule/core assemblies. However, after uptake by cancer cell lines (SKOV-3 cells), the SAR values of the free IONCs were significantly lower than those observed for capsule/core assemblies, especially after prolonged incubation periods (24 and 48 h). These results show that IONCs packed into submicrocavities preserve the magnetic losses, as the SAR values remained almost invariable. Conversely, free IONCs without the protective capsule shell agglomerated and their magnetic losses were strongly reduced. Indeed, IONC-loaded capsules and free IONCs reside inside endosomal and lysosomal compartments after cellular uptake and show strongly reduced magnetic losses due to the immobilization and aggregation in centrosymmetrical structures in the intracellular vesicles. The confinement of IONCs into sub-micrometer cavities is a key strategy to provide a sustained and predictable heating dose inside biological matrices.

CaCO3 supplementation of low-carbon wastewaters for the cultivation of Microalgae : a study with Desmodesmus multivariabilis

Microalgal biomass cultivated in wastewater has the potential for refining to energy products such as biodiesel and biohydrogen with the additional benefit of also treating the wastewater. As many species of microalgae can employ both Heterotrophic and Autotrophic modes of carbon synthesis, low-carbon waters benefit from the addition of inorganic carbon to the water. Capital and operational costs are a deterrent to using CO2 and other alternatives may be more attractive. NaHCO3 is a popular alternative but as a result of its solubility and alkalinity quickly raises the pH of the water which inhibits algal growth due the presence of free ammonia at high pH values. In this experiment, the growth of a South African strain of Desmodesmus multivariabilis was studied in the presence of solid calcium carbonate. Calcium carbonate was chosen for its low solubility, which would potentially allow for its dissolution to be driven by the inorganic carbon uptake in the media. The performance was compared to that of aerated wastewater and wastewater with solid CaSO4 as a non-carbon-containing substitute. It was found that there were significant differences in the growth and metabolism of all three experiments. Growth in the presence of solid calcium carbonate and calcium sulphate showed a preference for attached growth in the vicinity of solids, while suspended growth was preferred when just air was supplied. Furthermore, the experiment with air showed the highest growth rate, nitrogen uptake and a biomass yield that was more than an order of magnitude higher than with CaCO3. The experiment with CaSO4 showed low yields and growth rates, possibility indicating and inhibitory effect of the CaSO4. In the presence of CaCO3, a very high yield of extracellular organic metabolites was observed. The presence of these metabolites, as well as the stability of the pH and low growth, is a possible indication that the organism was controlling the pH as a defence mechanism. Despite not being a favourable substrate for growing D. multivariabilis, the high yield of extracellular metabolites may have a commercial potential, and the nature and use these metabolites deserve further investigation.

SOLID CaCO3 FORMATION IN WATERS OF CIRCULATING COOLING SYSTEMS OF POWER PLANTS UNDER THE CONDITIONS OF ELECTRIC LOAD CHANGE

The rate of solid calcium carbonate (Dve) formation in circulating water (CW) of circulating cooling systems (CCS) of power plants with cooler towers and the stability index of such water at changing electric load is analyzed. The relationship between streams of CCS, namely, feeding, evaporation and blow, which exist under the condition of constant CCS water volume and dependence of evaporation flow upon units load are the basis of analysis. Such dependence is based on the fact that the main channel of heat dissipation after steam turbine units is evaporation in cooling towers. The general expression has been obtained in quasiequilibrium approximation that establishes the relation between Dve and CW stability index. This dependence allows calculating CW stability degree for any models of CaCO 3 formation kinetics and to obtain corresponding Dve value. It has been shown that the rate of solid CaCO 3 formation is directly proportional to electrical load of power plant, Ca 2+ ion concentration in feed water and fraction of used heat dissipated by evaporation, antiproportional to stability index, inverse to CCS water volume and the average efficiency of power plant.

Experimental investigation on size degradation of bridging material in drilling fluids

Solid particle size distribution (PSD) of drilling fluids is one of the key factors for the formation damage and lost circulation control. However, particle size degradation occurs during the long-term process of drilling fluid circulation in the wellbore, consequently resulting in severe formation damage. In this study, size degradation experiments of calcium carbonate solids in the period of drilling fluid circulation are conducted to understand the effect of initial particle size, rotation speed, shear time, fluid viscosity, temperature, pH, salinity, and solid concentration on size degradation of bridging material (BM). The size degradation rate of D90 is taken as the characterization of particle size degradation. The results show that ① the degree of size degradation sharply increases with increasing solid initial size, rotation speed, and shear time. Under the experimental conditions, size degradation rate of sample with D90 = 44.153 μm is up to 30%~40% at a rotation speed of 1000 rpm over 30 min; ② there is a critical particle size in the range 15–20 μm for size degradation over 90 min. When the particle size drops to this critical size, no size degradation occurs obviously; ③ size degradation decreases with increasing fluid viscosity; ④ fluid temperature, pH, salinity, and solid concentration have little effect on size degradation. The evaluation criterion of size degradation is established, and an empirical model is developed to calculate the size degradation. Two mechanisms of the formation damage induced by size degradation are revealed. Based on the particle size degradation, the strategy for the optimization of PSD and solid supplement is presented. We believe that this strategy will be of great significance to designing the particle size distribution of BM for drilling fluids in the field.

Interactive Effects of Water Chemistry, Hydrodynamics, and Precipitated Calcium Carbonate Causing Erosion Corrosion of Copper in Hot Water Recirculation Systems: Case Study and Experimental Work

Erosion corrosion, or flow-induced failure, of copper is a complex phenomenon driven by a multitude of water quality, hydrodynamic, and electrochemical factors. This most common form of corrosion attack in hot water is likely to increase with newer Legionella risk-management regulations promulgating increased water recirculation, hotter water temperatures, and higher chlorine disinfectant dose. The current work reports findings from an investigation into widespread copper plumbing failure due to erosion corrosion in a large building complex by systematically exploring the effects of relevant water chemistry and hydrodynamic variables on localized erosion corrosion attack. The results seriously call into question decades of conventional wisdom by demonstrating that hard waters are not inherently less aggressive than soft water; in fact, if calcium carbonate solids form they can become even more aggressive. Entrained particles significantly accelerated attack on copper pipe walls, especially in high-turbulence areas like bends. This is the first research study to reliably reproduce rapid erosion corrosion failures in realistic potable water chemistry in the laboratory.

Effect of Corrosion Inhibitors on In Situ Leak Repair by Precipitation of Calcium Carbonate in Potable Water Pipelines.

Corrosion inhibitors can affect calcium carbonate precipitation and associated in situ and in-service water distribution pipeline leak repair via clogging. Clogging of 150 μm diameter leak holes represented by glass capillary tubes, in recirculating solutions that are supersaturated with calcite (Ωcalcite = 13), demonstrated that Zn, orthophosphate, tripolyphosphate, and hexametaphosphate corrosion/scaling inhibitors hinder clogging but natural organic matter (NOM) has relatively little impact. Critical concentrations of phosphates that could inhibit leak repair over the short-term in one water tested were: tripolyphophate (0.05 mg/L as P) < hexametaphosphate (0.1 mg/L) < orthophosphate (0.3 mg/L). Inhibitor blends (Zn+orthophosphate and Zn+NOM+orthophosphate) had stronger inhibitory effects compared to each inhibitor (Zn, orthophosphate or NOM) alone, whereas Zn+NOM showed a lesser inhibitory effect than its individual component (NOM) alone due to formation of smaller CaCO3 particles with a much more negative zeta-potential. Overall, increased dosing of corrosion inhibitors is probably reducing the likelihood of scaling and in-service leak repair via clogging with calcium carbonate solids in potable water systems.

Impact of Friction on the Uniaxial Soil Sample Compression Process

Abstract The objective of the research was to determine the impact of the friction force between the cylinder wall and soil on the soil compaction resistance in relation to the sample height and diameter of the compaction plate. Samples with the diameter of (D) 100 mm and heights (H) of 30, 50 or 100 mm made of of soil material collected from subsoil of the selected plastic soils were used. The soil material wasidentified by the following properties: the granulation type, density of the solid phase, humus and calcium carbonate content, reaction, plastic and liquid limit. Properties of the samples were described with moisture, dry density of solid particles, porosity of aeration, plastic degree and saturation. The samples were loaded with plates of varied diameters (d A: 20; 30; 50; 70; 80; 90 and 98 mm) measuring at the same time forces on the main plate (F A) and the bottom one (F B) with the fixed diameter (d B=98 mm). The registered relationships between the forces F A and F B and plate sinkage (samples deformation) were used for determination of the impact of external friction forces (between the cylinder wall and soil) on the compression resistance of soils. It was found out that the participation of the friction force in relation to the height of samples and plate diameter varied from 0 to ca. 70%. It was proved that one may avoid the impact of the plate diameter d A on the measurement of force F A, when the relation d A /D, for samples with the heights of H30 and H50, is respectively within 0.5 ≤ d A /D &lt; 0.8 and 0.5 ≤ d A /D &lt; 0.7.

Calcium Carbonate Mineralization in a Confined Geometry

Injection of CO2 in porous aquifers, where mineralization takes place via chemical reactions, is one possible long-term solution considered for storage of this greenhouse gas. This mineralization is investigated here experimentally in a confined geometry by injecting radially an aqueous solution of carbonate into a solution of calcium ions to produce solid calcium carbonate. Various precipitation patterns are observed depending on the injection rate and concentrations of the reactants. The pattern properties are quantified to analyze the influence of the growth conditions on mineralization. We show the existence of critical concentrations of reactants, which are functions of the flow rate, above which the amount of precipitate drops significantly.

Mineral Carbonation of Phosphogypsum Waste for Production of Useful Carbonate and Sulfate Salts

Phosphogypsum (CaSO4·2H2O) waste is produced in large amounts during phosphoric acid (H3PO4) production. Minor quantities are utilized in construction or agriculture, while most of the material is stockpiled, creating an environmental challenge to prevent pollution of natural waters. In principle, the gypsum waste could be used to capture several hundred Mt of carbon dioxide (CO2). For example, when gypsum is converted to ammonium sulfate ((NH4)2SO4) with ammonia (NH3) and CO2, also solid calcium carbonate (CaCO3) is generated. The ammonium sulfate can be utilized as a fertilizer or in other mineral carbonation processes that use magnesium silicate-based rock as feedstock, while calcium carbonate has various uses as e.g. filler material. The reaction extent of the described process was studied by thermodynamic modeling and experimentally as a function of reactant concentrations and temperature. Other essential properties such as purity and quality of the solid products are also followed. Conversion efficiencies of >95% calcium from phosphogypsum to calcium carbonate are obtained. Scalenohedral, rhombohedral and prismatic calcite particles can be produced, though the precipitates contain certain contaminants such as rare earth metals and sulfur from the gypsum. A reverse osmosis membrane cartridge is also tested as an alternative and energy-efficient method of concentrating the ammonium sulfate salt solution instead of the traditional evaporation of the process solution.