Precipitation Of Inorganic Salts Research Articles

Combined settlement and clogging in drainage sand layer for suspended solids, colloids and inorganic salts

Blockage of leachate drainage facilities is a common engineering problem in landfill operation. The key factors that cause blockage of drainage facilities in landfill leachate are the deposition of suspended solids (SS) with colloids and the precipitation of inorganic salts. To determine the combined sedimentation law of SS, colloids and inorganic salts, a combined sedimentation test of suspended solids, colloids and inorganic salts was conducted. To further clarify the resulting clogging characteristics of the water-conducting sand layers, a sand column blocking test were conducted, and mineral composition and grain characteristics of sediments were determined. The experimental results shown that the colloids (silver iodide) and inorganic salts (calcium chloride or aluminum sulfate) increased the sedimentation rate of SS by 8 to18 times. Among them, the effect of AgI colloid was the most significant, followed by effect of calcium chloride, while effect of aluminum sulfate was the weakest. Compared with sand column clogging caused by SS, this combined migration shortened the sand column clogging time by more than half and reduced hydraulic conductivity by nearly two to three orders of magnitude. This study contributes to the accurate assessment of the service performance of landfill leachate drainage systems.

Optical coherence tomography and digital image processing for scaling and Co-precipitation investigation on reverse osmosis membrane

Scaling known as the precipitation of inorganic salts is a main concern in the reverse osmosis (RO) process due to its effects on the process performance and life-time of membranes. Although single salt precipitation has been continuously studied, the co-precipitation of salts is rarely investigated due to its complexity, especially under process hydrodynamic conditions. Recently, optical coherence tomography (OCT) has been adopted as an in situ and rapid technique for monitoring the fouling in membrane processes. This study aims to develop an approach using OCT and digital image processing for qualitative and quantitative analysis of single salt precipitation and co-precipitation on RO membrane under hydrodynamic conditions. The effects of supersaturation, sodium chloride (NaCl), flow rate, and applied pressure are investigated. The developed approach enables the detection of crystal growth under the OCT. The morphology of precipitated salt, i.e CaSO4, including crystal shape and size obtained from OCT acquisition, agrees with the images from a scanning electron microscope (SEM). The growth of each crystal in co-precipitation of CaSO4 and CaCO3 is well detected in appearance time and growth pattern. This is beneficial to differentiate crystal morphology in the co-precipitation system. The quantitative surface coverage proportion and total volume are in well correlated the changes of RO performance parameters of permeate flux, conductivity (feed, concentrate, and permeate), and Ca2+ concentrate profile by time, which allows the scaling progress to be directly evaluated over time. This study reveals the high potential of combining OCT acquisition and digital image processing for direct observations and studying single salt and co-precipitation under RO hydrodynamic conditions, which can be extended for another type of composite fouling.

A novel approach based on RGB image analysis for the investigation of scale formation and performance of inhibitors under flow conditions

Scale is one of the main flow assurance issues in oil and gas production because reduces productivity or even stops production. The evaluation of scale formation and performance of inhibitors under flow conditions is essential for managing this problem. A conventional method for this evaluation is the tube-blocking test performed in a dynamic scale loop (DSL) system monitoring the differential pressure caused by the scale formation. However, this system does not provide information to understand the precipitation process prior to scaling and the inhibition mechanisms. This work presents a novel approach based on RGB (red, green, and blue) image analysis for the investigation of scale formation and performance of inhibitors under flow conditions. This approach uses a viewing cell coupled to the output of a DSL that allows detecting the inorganic salt precipitation and formation of its deposits under flow conditions via RGB image analysis. Several calcium carbonate scale experiments were conducted by mixing different concentrations of bicarbonate ions (1,000–4,000 mg L−1) with calcium ions (4,000 mg L−1) and controlling the temperature (80 °C), flow rate (10.0 mL min−1), ionic strength (19,980 and 40,000 mg L−1 of Cl−), and pH (6.8). The results via RGB image analysis agreed with those provided by the differential pressure, including the evaluation of the performance and minimum inhibitory concentration of three chemicals: EDTA and two commercial inhibitors. This novel approach not only allows the determination of the scale formation time as the DSL but also allows the study of crystallization and crystals growth. Furthermore, it provides information helpful to better understanding the inhibition mechanisms.

Thermoresponsive homo-polymeric ionic liquid as molecular transporters via tailoring interchain π-π interactions and its unique temp-resistance behavior during ions pairing

In this study, a polymeric ionic liquid (PIL) called Poly[ECH-BIM]Cl was polymerized by ring-opening and quaternization reaction of benzimidazole and epichlorohydrin without additional ion-exchange reaction. Both 1H NMR and fourier transform infrared (FTIR) confirmed the chemical structure of Poly[ECH-BIM]Cl. Poly[ECH-BIM]Cl in water was thermoresponsive and its UCST transition was studied by UV–vis spectrometry, dynamic light scattering (DLS) and scanning electron microscopy (SEM) at variable temperature. Moreover, the first introduced Temp-resistance behavior during ions pairing found Poly[ECH-BIM]Cl had properties similar to those of the precipitation of inorganic salts from their saturated solutions. The variable-temperature 1H NMR analysis demonstrated that the tailored interchain π-π interactions promoted the aggregation of macromolecular chains and particles formed from Poly[ECH-BIM]Cl aqueous solution. The results showed that increasing the interaction between cations of PIL can endow its thermosensibility and the possibility of being a programmable shuttle.

Experimental Study on Solidification Characteristics of Sessile Urine Droplets on a Horizontal Cold Plate Surface under Natural Convection.

As the human excreta, urine is often used as one of the test materials in medical research due to its composition and content directly reflecting the health status of the body. Considering that the substances in urine may show different effects on its freezing process, solidification characteristics of sessile urine droplets on a horizontal cold plate surface under natural convection were experimentally investigated by comparing with those of water droplets under same conditions. To make the conclusion analysis more reasonable, the urine of a human without any diseases, especially metabolic diseases, was treated and used. The characteristics include nucleation location, dynamic variation of droplet color, and temperatures at different heights inside the droplet, and so forth. It was found that, similar to that of a water droplet, the solidification process of a urine droplet also experiences the following four stages: supercooling, recalescence, freezing, and cooling, in chronological order. Differently, the urine droplet changes from transparent to blur white at the supercooling stage due to the precipitation of inorganic salts. For nucleation locations, 46.67% cases are at the bottom, while others are at the top and middle of urine droplets. For a 10 μL droplet on a surface of -30 °C, urine has a 0.95 s freezing duration shorter than water, and a 5.31 °C lower phase-transition temperature. Results of this study are expected to reflect the content of substances in urine and thus provide references for urinalysis of patients with metabolic diseases.

An experimental study of calcium carbonate precipitation with hydrate inhibitor in MEG recovery unit

Monoethylene glycol (MEG) is a thermodynamic inhibitor of gas hydrate formation used in the oil industry. Regeneration of MEG for reinjection in wells is necessary to minimize operating costs due to the large amounts of this additive employed. However, this scenario favors the precipitation of inorganic salts from the produced water, mainly calcium carbonate (CaCO3). This work is devoted to evaluating the CaCO3 precipitation in water + MEG mixtures (0–50 vol.% MEG) at different concentrations of reacting salts (0.01–0.1 mol L−1) and temperatures (25–60 °C). The focused beam reflectance measurement (FBRM) technique was used for inline monitoring of chord length and CaCO3 particles distribution in the suspension for 60 min. Optical microscopy was used to understand the particle precipitation phenomena. FBRM results show that the size distribution and the number of CaCO3 particles in the aqueous solution vary with time, temperature, reacting salts, and MEG concentrations. The higher the salt concentration, the larger both the size and number of precipitated chords. Temperature expressively affects salt precipitation. For a given concentration of MEG, the enhancement in temperature favors the increase in the amount and size of chords. Specifically, for 10% v/v of MEG solutions, the particle size increases from 8.0 ± 0.5 μm (at 25 °C) to 20.4 ± 2.1 μm (at 60 °C). Additionally, at 30% v/v of MEG in the solution, the particle size increases from 5.4 ± 0.4 μm (at 25 °C) to 15.5 ± 0.2 μm (at 60 °C). These outcomes are related to the reduction in CaCO3 solubility and the improvement in MEG viscosity with temperature. Optical microscopy measurements corroborate the FBRM data, thus demonstrating the influence of the parameters MEG concentration, ionic concentration, and temperature have on the number and size of precipitated carbonate crystals.

The effect of inorganic salt precipitation on oil recovery during CO2 flooding: A case study of Chang 8 block in Changqing oilfield, NW China

Static experiments and dynamic displacement experiments were conducted to quantitatively determine the amount of precipitate generated by the CO 2 -formation water reaction at different temperatures, pressures, and scaling ion concentrations during CO 2 flooding in the Chang 8 block of Changqing Oilfield, the influence of precipitate on the physical properties of reservoirs was investigated, and the corresponding mathematical characterization model was established. The mathematical characterization equation was used to correct the numerical simulation model of E300 module in Eclipse software. The distribution pattern of inorganic salt precipitates during continuous CO 2 flooding in Chang 8 block was simulated, and the influence of inorganic salt precipitates on oil recovery was predicted. The inorganic salt precipitate generated during CO 2 -formation water reaction was mainly CaCO 3 , and the pressure difference and scaling ion concentration were proportional to the amount of precipitate generated, while the temperature was inversely proportional to the amount of precipitate. The rate of core porosity change before and after CO 2 flooding was positively correlated with temperature and flooding pressure difference. The core porosity increase in the CO 2 -formation water-core reaction experiment was always lower than that of CO 2 -distilled water-core reaction experiment because of precipitation. The area around the production wells had the most precipitates generated with the injection of CO 2 . The oil field became poor in development because of the widely distributed precipitate and the recovery decreased to 33.45% from 37.64% after 20-year-CO 2 flooding when considering of precipitation.

Microalgal exopolymeric substances fouling in submerged vacuum membrane distillation and its mitigation via enhanced air bubbling

This work aims at studying the fouling behaviour of submerged vacuum membrane distillation (S-VMD) in desalinating the algal-blooming seawater. A dynamic microalgal fouling phenomenon and its mitigation via air bubbling was investigated over the time. At the early stage of S-VMD operation, the precipitation of inorganic salts on the membrane surface was responsible for initiating the flux decline. In the later stage, significant amounts of EPS surrounding the microalgae cell aggregates were precipitated on the inorganic scalants and further increased the membrane fouling rate. Based on the exopolymeric substances (EPS) extraction analysis, hydrophilic polysaccharides as a result of the aggregation of microalgal cells was firstly observed, followed by dominating protein fouling over the long run S-VMD operation. Excreted proteins increased the hydrophobicity of the EPS by reducing the surface charge, thus leading to a strong hydrophobic interaction with membrane surface at the 60 h of S-VMD operation. Compared to the non-bubbling S-VMD system, the system subjected to 0.167 m/s air bubbling showed superior and stable flux performance with lower extent of fouling.

Mathematical Characterization of Inorganic Salt Precipitation From the Reaction of CO2 With Formation Brine and Its Application

In the process of CO2 enhanced oil recovery (CO2-EOR), CO2interacts with formation brine containing high concentrations of scale-forming ions to produce inorganic salt precipitation, which blocks the rock pore throats, changes the characteristics of the reservoir and thereby reduces the oil recovery rate. In this study, a series of experiments on the static reaction of CO2-formation brine were conducted. The amounts of precipitation formed from the interaction of CO2-formation brine under various conditions were tested. Using the PHREEQC software, the mathematical characterisation formulas between the precipitation amount and various environmental factors (e.g. temperature, pressure difference, scale-forming ion concentration and pH) were established. On this basis, a numerical simulation model of CO2 flooding in a typical area of Oilfield C was established. The distribution of inorganic salt precipitation during continuous gas flooding was predicted, and the effect of inorganic salt precipitation on oilfield recovery was analysed.

Precipitation of Inorganic Salts in Mitochondrial Matrix.

In the mitochondrial matrix, there are insoluble, osmotically inactive complexes that maintain a constant pH and calcium concentration. In the present paper, we examine the properties of insoluble calcium and magnesium salts, such as phosphates, carbonates and polyphosphates, which might play this role. We find that non-stoichiometric, magnesium-rich carbonated apatite, with very low crystallinity, precipitates in the matrix under physiological conditions. Precipitated salt acts as pH buffer, and, hence, can contribute in maintaining ATP production in ischemic conditions, which delays irreversible damage to heart and brain cells after stroke.

Inorganic mineral precipitation from potable water on heat transfer surfaces

In this study, an experimental approach mimicking processes encountered in electric kettles has been designed to investigate the influence of heating and cooling rate, and water composition on the kinetics of inorganic salt precipitation taking place when water is heated from ambient temperature up to its boiling point. The kinetics of salt precipitation in the bulk solution have been monitored through turbidity measurements as well as tracking ion concentration throughout the heating/cooling process and the experimental findings highlight the critical role of the cooling step on the overall amount of salts that precipitate. The presence of magnesium ions in the water was found to influence the precipitation of calcium carbonate which was found to be the dominant salt crystallising out of solution; calcium sulphate was not observed.

Use of a dynamic system and reflectance measurements to assess the impact of monoethylene glycol on calcium carbonate scale

The build-up of scale in petroleum production systems is a major hindrance to the efficient production of oil and gas. One of the most common types of scale is calcium carbonate, but the formation of gas hydrate is also a recurring concern, especially in offshore and subsea deep water production. Thermodynamic inhibitors are usually used to avoid hydrate formation, but they contribute to the precipitation of inorganic salts. As monoethylene glycol (MEG) is the most commonly used thermodynamic inhibitor, the purpose of this work was to evaluate the effect of MEG on the formation of calcium carbonate scale using a Dynamic Scale Loop (DSL) to evaluate scale inhibitors. The results show, as expected, that the larger the amount of MEG, the lower the calcium carbonate scale formation time. In addition, to better understand the DSL results and the formation and growth of crystals, focused beam reflectance measurement (FBRM) was performed. The results confirm that the addition of MEG decreases the growth rate by hindering the agglomeration of crystals due to an increase in the viscosity of the solutions.

Increasing efficiency of calcium sulfate scale prevention using a new mixture of phosphonate scale inhibitors during waterflooding

Inorganic salt precipitation is one of the main problems in oilfield operations. Different factors affect scale formation and inhibition. Calcium sulfate scale formation occurs during waterflooding due to incompatibility of injection and formation waters. In this work, synthetic formation and injection waters were prepared to determine the influence of reservoir conditions (temperature and pressure), and mixing ratio of the waters on calcium sulfate scale deposition during waterflooding. A new mixture of phosphonate scale inhibitors (SI) was developed for increasing the inhibition efficiency of calcium sulfate scale formation in oil reservoirs. The developed mixture consists of three different industrial phosphonate SI and some additives. The concentrations of components of the developed mixture of phosphonate SI were determined on the basis of a synergistic inhibition effect. The maximum value of the synergistic inhibition effect was about 1.091. Performance of the developed mixture and four different industrial SI (HEDP, ATMP, PPCA and DTPMP) was determined by jar test. The experimental results showed that the developed mixture of phosphonate SI has a better inhibition performance than the industrial inhibitors under any conditions. Its effectiveness was more than 90% at any reservoir temperature (60–120 °C) and content of formation water in the solution (10–90%). Furthermore, a minimum inhibitory concentration of the developed mixture of phosphonate SI was about 25 mg/L. Moreover, formation damage due to calcium sulfate precipitation in carbonate rock samples with and without the use of scale inhibitors was investigated. Without the addition of any SI, the damaged permeability was about 58% of the initial rock permeability. The damaged permeability in the presence of the developed mixture of phosphonate SI was about 93.5% of the initial permeability of the used rock samples. Also, a new correlation was developed for predicting a permeability reduction of the rock samples due to calcium sulfate precipitation. The coefficient of determination between experimental and predicted (form correlation) data was 0.99. In addition, the developed mixture of phosphonate SI had the enhanced adsorption/desorption capacities. Its squeeze lifetime was longer up to 22.6% than other inhibitors. The corrosion rate in the solution of the developed mixture of phosphonate SI was lower than 0.063 mm/y at any concentration.

Solubilities and Glass Formation in Aqueous Solutions of the Sodium Salts of Malonic Acid With and Without Ammonium Sulfate.

The solubility of sodium hydrogen malonate and sodium malonate in water both with and without ammonium sulfate present has been studied using differential scanning calorimetry and infrared spectroscopy. The crystals that form from sodium hydrogen malonate/water solutions were determined to be sodium hydrogen malonate monohydrate by single-crystal X-ray diffractometry. The crystals formed in sodium malonate/water solutions were determined to be sodium malonate monohydrate, a compound whose structure had not been previously known. When ammonium sulfate is added to these respective aqueous systems, the precipitation solids contain sodium sulfate decahydrate under low to moderate ammonium concentrations and lecontite (NaNH4SO4·2H2O) under high ammonium concentrations, which can be found under dry atmospheric conditions. Thus, it appears the presence of malonate and hydrogen malonate ions does not significantly affect the precipitation of inorganic salts in these systems. The glass transition temperatures of all solutions were also determined, and it was observed that the addition of ammonium sulfate slightly lowers the glass transition temperature in these solutions.

Effect of Temperature and Composition on the Stability of Crude Oil Blends Studied with Chemical Imaging in Situ

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging approach has been applied in situ to investigate the behavior of crude oil blends at different conditions. The ratio between mixed crude oils and temperature has been varied to study how these factors influence the stability of the blends. Obtained spectroscopic results have been used to correlate the composition of the blends with respect to the incompatibility of crude oils. The chemical compositions of precipitates formed from the blends at 60 and 200 °C have been examined by FTIR spectroscopy. The change of asphaltene solubility in crude oil blends as well as the precipitation of inorganic salts, sulfates, have been observed at higher temperature. Based on available spectroscopic data, the formation of hydrogen bonds between sulfoxide groups of precipitated inorganic sulfates and hydroxy groups of asphaltenes or similar condensed aromatic species has been proposed.

INVESTIGATION OF THE ASPHALTENE INHIBITOR EFFECT ON REDUCTION OF THE SCALING INTENSITY IN FORMATION AND WELLS

In this paper, the problem of precipitation of inorganic salts and their prevention are discussed during development of oilfields. Scale inhibitors are used to control the formation of inorganic salts in the fields. The effectiveness analysis of the scale inhibitors is essential because active concentrations of scale inhibitors are low and must be accurately measured. The addition of polymer asphaltene inhibitor in a scale inhibiting system affects the crystallization and efficiency of the scaling prevention in the downhole equipment and the bottom zone of productive formations. In this paper, the results of using inhibitor, which is a composition that based on nitrilotrimetilfosphonic acid to prevent calcium sulfate precipitation, are presented. The changes in the concentration of the salt by using an asphaltene inhibitor are considered in carbonate reservoir type core samples. The calcium sulfate induction period is investigated in the presence of the polymeric asphaltene inhibitor. Efficiency of scaling prevention is evaluated by measuring the mass of the formed salts in the core samples in the presence of the asphaltene inhibitor. The peak of the calcium sulfate deposition occurs at a total mineralization of 140 g/l of formation water. The results of the experiments showed that the asphaltene inhibitor has a negative effect on the inhibition of calcium sulfate. The driving force of calcium sulfate deposition is sharply decreased in the presence of the asphaltene inhibitor with decreasing the induction period. This force obtains the minimum value within 49 minutes of the induction period. The results of investigation can be used to effectively protect the carbonate reservoirs and downhole equipment from the calcium sulfate precipitation in the presence of the asphaltene inhibitor.

Fabrication of gel cast BN/Si3N4 composite ceramics from surface-coated BN powder

BN/Si3N4 composite ceramics with different BN content were prepared by water-based gel casting process with raw and Y–Al-oxides-coated BN powder, separately. A Y–Al oxides layer with the thickness ranging from dozens to hundreds of nanometers, serving as sintering additives, was coated on the surface of BN particles with the method of precipitation of inorganic salts. As a result, the fluidity of BN/Si3N4 slurry with Y–Al-oxides-coated BN powder was much improved compared to that with raw BN. SEM examination showed the Y–Al-oxides-coated BN particles were homogeneously distributed within the Si3N4 grain boundaries, and BN aggregation was barely detected. The BN/Si3N4 composite ceramic prepared by Y–Al-oxides-coated BN powder showed a better sintering behavior than those prepared by raw BN due to the formation of fine and homogeneous microstructure in it. Compared to the BN/Si3N4 ceramic with 15vol% raw BN, the density and flexural strength of the ceramic with the same content of surface-coated BN were significantly improved to 8.5% and 67.2%, respectively.

Advantages obtained through the elimination of chemical products in the pre-treatment process of large desalination plants for the control of fouling, biofouling and scaling in reverse osmosis membranes

Abstract This paper presents the results of research work conducted as part of a doctoral thesis and undertaken with the aim of resolving the problem of accelerated fouling of reverse osmosis membranes (made from spiral-wound polyamide), as a result of the deposition of colloidal particles (particulate fouling), the precipitation of inorganic salts (scaling) and the accumulation of living and/or dead biological matter (biofouling). The reverse osmosis modules affected form part of the Las Palmas III (LP3) desalination plant run by the company EMALSA (Spanish initials: Empresa Mixta de Aguas de Las Palmas). This plant is located on the island of Gran Canaria (Spain) and supplies potable water to around half a million people.

Effects in the solubility of CaCO3: Experimental study and model description

Crude oil is usually co-produced with reservoir water, with increasing content in the production fluid along field life. Changes in temperature, pressure, and/or chemical composition may cause significant precipitation of inorganic salts (“scales”) during production. Therefore, the knowledge of the influence that different variables may have on salt solubility is critical to anticipate or identify potential flow assurance problems related to scales. The present work is specifically focused in the study of calcium carbonate precipitate formation as a main component of “scales”. Due to the number of variables involved in calcium carbonate precipitation (temperature, pressure, CO2 partial pressure, other salt content) and the heterogeneity of reservoir conditions, there are serious limitations to perform a full experimental study covering all the possible precipitation scenarios. Solubility data presented in this work, both previously reported and experimentally determined, cover a wide range of experimental conditions.A simulation model that allows quantitative predictions in different scenarios is an interesting tool. A versatile simulation algorithm was developed using ASPEN PLUS® 7.1 from Aspen Technology, Inc., that allows different experimental conditions and the quantification of the influence of temperature, pressure and pH in CaCO3 solubility. This simulation scheme was applied to describe both literature and new experimental solubility data. Predicted results were in reasonable agreement with experimental information. The solubility of calcium carbonate decreases with temperature, increases with pressure and shows a maximum in presence of NaCl. The CO2 partial pressure has strong effect because it is direct relation with solution pH that modify the amount of ionic species present in the aqueous solution, and hence increasing the solubility of calcium carbonate. Special attention was devoted to such pH effect but, in order to have a fully predictive model, no parameters fit was carried out. The main conclusion of this work is the suitable simulation scheme to describe and predict the solubility of calcium carbonate at different conditions.

High recovery of concentrated RO brines using forward osmosis and membrane distillation

Vacuum-enhanced direct contact membrane distillation (VEDCMD) and forward osmosis (FO) were investigated for water recovery enhancement in desalination of brackish water. Past studies have demonstrated that both VEDCMD and FO can be effectively utilized in the treatment of a wide range of highly concentrated feed solutions. In the current study, two reverse osmosis (RO) brine streams with total dissolved solids concentrations averaging 7500 and 17,500 mg/L were further desalinated by VEDCMD and by FO. In both processes, high water recoveries were achieved; however, recoveries were limited by precipitation of inorganic salts on the membrane surface. Various cleaning techniques were able to remove the scale layer from the membrane and restore water flux to almost initial levels. FO achieved water recoveries up to 90% from the brines and VEDCMD achieved water recoveries up to 81% from the brines. Addition of a scale inhibitor during both processes was effective at maintaining high water flux for extended time. When considering the total water recovery (the recovery from the RO processes combined with the batch recovery from the VEDCMD or FO process), greater than 96 and 98% total recoveries were achieved for the two different brine streams.