Scale Inhibition Performance Research Articles

Investigation of scale inhibition effect and mechanism of S-HGMF in the clean recirculating cooling water system

The formation of scales in a recirculating water system is a common problem in industrial water treatment; it seriously affects the production in various industries and pollutes the environment. Although conventional scale inhibition methods are effective, they are expensive and harm the environment. Herein, an advanced method is proposed to solve the scaling issue in recirculating cooling water systems using the superconducting high-gradient magnetic field (S-HGMF) treatment. The scale inhibition performance could be improved by changing the magnetic flux density, operation time, and flow rate. The results showed that S-HGMF could increase the number of hydrogen bonds in the recirculating cooling water, enhance molecular interaction, increase the thickness of the ion hydration shell, reduce the nucleation rate, stabilize the water quality, improve the solubility of scale-forming ions, and inhibit scale formation. The scale inhibition performance reached 8.10%. Interestingly, S-HGMF had a memory effect in that it could maintain the scale inhibition effect for some period after treatment completion. Moreover, S-HGMF changed the crystal structure of the scale and promoted the transformation of the scale to a metastable phase. Ultimately, calcite was transformed to aragonite to reduce the precipitation of hard scale (calcite), achieving the purpose of scale inhibition. As a physical method, the application of S-HGMF to inhibit scaling has great potential for industrial applications.

The evaluation of Bacillus-secreted polyglutamic acid as anti-scaling treatment for circulating cooling water.

Polyaspartic acid is considered a green agent for the treatment of circulating cooling water. However, its chemosynthetic process is not green, as it requires significant amounts of energy and causes water pollution. In this work, we identified an analog of polyaspartic acid, namely polyglutamic acid (γ-PGA), which could be directly produced by Bacillus spp., and we explored its performance and scale inhibition mechanism as a scale inhibitor. We found that γ-PGA secreted by B. megaterium with a molecular weight of ~ 70kDa showed poor scale inhibition, while the γ-PGA secreted by B. licheniformis with a molecular weight of ~ 15kDa had a 26.87% higher efficiency compared to commercially available polyaspartic acid. The scale inhibition mechanism was explored using the γ-PGA material secreted by B. licheniformis. Fourier transform spectrometer, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy analysis demonstrated that the scale inhibition performance of γ-PGA was due to the combination of its functional groups and Ca2+, which affected the growth process of CaCO3 and inhibited the formation of CaCO3. This study provided deeper insight into scale inhibition performance related to the scale inhibition mechanism.

An investigation on scaling failure of heat exchanger in cooling water system of natural gas purification plant

AbstractIn this study, a natural gas purification plant adopts open circulating water system, which cannot work properly and hinder the normal production of natural gas due to the problems such as scaling and blockage in the operation of heat exchanger device was reported. Qualities of the make‐up water and recirculating cooling water were evaluated by parameters such as hardness, alkalinity, pH, and conductivity. X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and optical microscope were employed to study the crystal structure, composition, and morphology of the scale deposits. The flow rate of the water in the tube bundle was calculated according to the design scale of these exchangers. The Langelier Saturation Index (LSI) was used to analyze the scale tendency of the cooling water system. The scale inhibition performance of the inhibitor was verified by static inhibition method. Results show that the scale mainly contains calcium carbonate, and the quality of circulating water is reasonably controlled with a proper range. However, there are three units sharing one cooling water system, of which the flow rate cannot be adjusted according to the actual heat load. The calculation results confirmed that the circulating water velocity in the tube bundle did not exceed 0.9 m/s. Although the scale inhibitor has a scale inhibition efficiency of more than 90% for the simulated circulating water at 80°C, the LSI analysis results showed that the high local temperature on the surface of the tube bundle caused by the low flow rate of water will increase the scaling tendency of the heat exchanger. Furthermore, the untimely injection of the inhibitor in the daily management and operation also greatly increased the risk of system scaling. This paper proves that the scaling of circulating water heat exchanger in the purification plant is mainly caused by device design and poor daily management. In order to prevent future failures, potential solutions and mitigation strategies were put forward.

PH-responsive smart composite coating with active anticorrosion and efficient scale inhibition properties

In this work, porous polysulfone (PSF) microcapsules were prepared using the method of mixed solvent volatilization, these microcapsules were used as a carrier, 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) was used as an active substance for scale and corrosion inhibition, and stearic acid (SA) was used as a coating to prepare a pH-responsive smart microcapsule slow-release filler. Then, the smart microcapsules were added to a polyurea resin to prepare a pH-responsive smart composite coating with anti-corrosion and scale inhibition properties. The results showed that SA/PSF/HEDP microcapsules have significant pH-triggering activity in an alkaline environment. The alkaline supersaturated CaCO3 solution test showed that the composite coating has excellent scale inhibition performance. This is attributed to the in the microcapsules being released to the coating surface, achieving the purpose of complexation and solubilization. Local electrochemical impedance spectroscopic (EIS) proved that the SP/SA/PSF/HEDP composite coating has good corrosion resistance. This is attributed to the release of corrosion inhibitors, which can form a dense protective film on the metal. The scale inhibition efficiency of the composite coating was as high as 78.57 %, and the impedance modulus value is increased by three orders of magnitude.

Study on the Corrosion and Scale Inhibition Mechanism of the Thiourea-Modified Polyepoxysuccinic Acid (CNS-PESA)

In this paper, thiourea-modified polyepoxysuccinic acid (CNS-PESA) was synthesized and used as a corrosion and scale inhibitor for the circulating cooling water system of the factory. Polyepoxysuccinic acid (PESA) has been widely used in industrial water treatment due to its good corrosion inhibition and scale inhibition performance. It also acts as a reliable material for dispersion of iron oxide, good biodegradation efficiency, and phosphorus-free content. The scale inhibition performance for calcium carbonate and calcium phosphate scale with corrosion inhibition performance using different inhibitor concentrations, temperatures, pH, and calcium ion concentration on scale inhibition efficiency were studied. The scanning electron microscope (SEM) analysis on the scale and corrosion of carbon steel with two methods as GB/T 18175-2000 “Measurement of inhibitors in water treatment: rotation coupon method” and electrochemical method for CNS-PESA and PESA were utilized. Compared to using CNS-PESA and PESA for calcium carbonate and calcium phosphate, the scale inhibition rates were increased by 6% and 18.7%, and the corrosion inhibition rate increased by 22.4%. The scale inhibition efficiency of CNS-PESA is best when the calcium ion concentration is less than or equal to 350 mg/L. Moreover, the thiourea-modified polyepoxysuccinic acid (CNS-PESA) was phosphorus-free corrosion and scale inhibitor and minimizes environmental pollution problems.

Scale inhibition performance of an electric field on a heat transfer surface: Experiments and molecular dynamics simulation

Because of the electric field method has the characteristics of energy saving, environmental protection and high efficiency, it is the focus of research in this field at present. In this study, a molecular dynamics method was used to simulate the effect of an electric field on the interaction of Ca2+ and CO32− in calcium carbonate solution with the surface of calcite crystals (1, -1, 0), and through experiments, the performance of an electric field with an intensity of 1000–1400 V/m (step 100 V/m) to inhibit calcium carbonate deposition on the heat transfer surface was studied. The simulation results showed that the binding energy of Ca2+ and CO32− to the surface of calcite crystals (1, -1, 0) decreased after the application of an electric field. By analysing the diffusion coefficient and radial distribution function of Ca2+ and CO32−, the electric field was shown to effectively prevents the diffusion and combination of to the calcite (1, -1, 0) crystal plane, which can effectively prevent the growth of calcium carbonate on the heat transfer surface. The experimental results showed that the fouling resistance is significantly reduced after electric field treatment. The results of scanning electron microscopy (SEM) and macroscopic analysis of fouling on heat transfer surface also show that electric field can effectively inhibit fouling. When the electric field intensity is 1300 V/m, it has the best anti-scaling effect. Therefore, the calculation results are basically consistent with the simulation conclusions.

Evaluation of microbial agents as corrosion and scale inhibitor for industrial cooling water applications.

In this study, six strains of microbial agents were investigated as environmently friendly scale and corrosion inhibitors for industrial cooling water applications. The static jar tests along with characterization methods were applied to evaluate the scale inhibition performance. Results showed that under a concentration of 240 mg/L, the nitrobacteria, denitrobacteria and Lactobacillus agents reached high CaCO3 scale inhibition efficiencies of 83, 82, and 86% respectively. Characterization methods indicated the deposited crystals morphologies were modified and the crystals peak intensities were lowered. In addition, weight loss measurements, electrochemical measurements, surface characterization analyses were conducted to study the corrosion inhibition performances and mechanisms. It was found that at 40 °C, Bacillus cereus agent with 200 mg/L possessed the highest corrosion inhibition efficiency of 60.11% at 3 d, together with the second-lowest current density of 13.0 μA cm-2 at 12 d. The corrosion inhibition mechanisms were attributed to biofilm accumulation and biomineralization on Q235 CS surfaces to form protective film. The results suggested microbial agents have promising potential as environmently friendly scale and corrosion inhibitors for industrial cooling water applications.

Synthesis, characterization and scale inhibition performance evaluation of novel dendrimers with the initiator core of pentaerythritol derivative

In this work, a series of novel poly(amido amine) dendrimers with the initiator core of pentaerythritol derivative (denoted by PER-PAMAMs), environment-friendly phosphorus-free scale inhibitors, were synthesized through Michael addition reaction and amidation reaction by divergent approach. The chemical structures and functional groups of the synthesized products of different generations were characterized by Fourier transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR) techniques. The scale inhibition performance of PER-PAMAMs dendrimers on silicate scale and calcium carbonate scale was investigated by static scale inhibition experiments. The influences of concentration, working temperature, and pH value on the scale inhibition performance were evaluated systematically. The results indicate that PER-PAMAMs have good scale inhibition performance on both silicate scale and calcium carbonate scale, and 1.0G PER-PAMAM is superior to 2.0G PER-PAMAM. Furthermore, good synergistic effects were observed between PER-PAMAMs and PAPEMP, the silicate scale inhibition rate (24 h) of the composite formula, PER-PAMAM 1.0G (80 mg/L)/PAPEMP (15 mg/L), can reach about 95%. The calcium carbonate scale inhibition rate of the composite formula, PER-PAMAM 1.0G/PAPEMP (10 mg/L), can reach about 95%. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to analyze the scale depositions to deduce the underlying mechanisms.

Exploring Modified Alendronic Acid as a New Inhibitor for Calcium-Based Oilfield Scales

Organophosphorus compounds are well known as oilfield scale inhibitors. Earlier work showed that a series of new and well-known bone-targeting drugs incorporating non-toxic bisphosphonates (BPs) (PO3H2–C–PO3H2) gave good scale inhibition performance against calcite scale based on produced water from the Heidrun oilfield, Norwegian Sea, Norway. However, these chemicals showed only moderate calcium compatibility activity. In this project, we attempted to improve the inhibition performance and calcium tolerance of non-toxic BPs by introducing various functional groups (phosphonate (SI-2), sulfonates (SI-3 and SI-5), and carboxylates (SI-4, SI-6, and SI-7)) in the inhibitor structure backbone. All modified alendronic acid derivatives were screened for calcite and gypsum scale inhibition according to the NACE Standard TM0374-2007 protocol. We also report the calcite scale inhibition performance of all synthesized SIs according to the Heidrun oilfield, Norwegian Sea, Norway. In addition, the calcium tolerance and thermal stability activities of all synthesized SIs are reported. The tolerance results showed that all SIs gave better calcium compatibility than BPs reported earlier, with SI-5 giving the best results at high calcium concentrations (10,000 ppm). The corresponding attachment of an iminodi methylene/ethylene sulfonic moiety (i.e., SI-3 and SI-5) showed worse performance against gypsum scaling, whereas the methylenephosphonate derivative (SI-2) and the carboxylated derivatives (SI-4, SI-6, and SI-7) showed improved performance. For calcite scaling, the NACE standard test gave significantly lower inhibition results than the Heidrun-based produced water due to the former having a higher calcium concentration and calcite supersaturation. It was also found that SI-2, SI-5, and SI-7 showed good thermal stability at 130 °C for 1 week.

Effect of supercritical CO2 flooding on the produced water quality and performance of the scale inhibitors in a typical tight sandstone oilfield

In order to enhance oil recovery, supercritical CO2 (scCO2) flooding has been applied in many oilfields to extract oil and gas post primary recovery. However, it causes serious scaling problems in the reservoir, oil well and production tubing. In this article, the produced water quality before and after scCO2 flooding in carbonate reservoirs are analyzed. The scaling trend of produced water before and after scCO2 flooding was calculated by using the Davis-stiff saturation index and Ryznar stability index methods. Static experiments and scanning electron microscope (SEM) are used to study the scale inhibition performance and mechanism of HEDP, ATMP, MA-AA, and PAA on CaCO3 in produced water before and after scCO2 flooding. The results show that after scCO2 flooding, the quality of produced water changes obviously, thus the scaling trend of produced water increases, the growth of CaCO3 crystal is affected and the scale inhibition efficiency of conventional scale inhibitors decreases.

Characterization of scalants and strategies for scaling mitigation in membrane distillation of alkaline concentrated circulating cooling water

Treatment of circulating cooling water via reverse osmosis for water reuse is attractive. However, the discharge of the concentrated circulating cooling water (CCCW) is still an issue to environment. In this paper, direct contact membrane distillation (DCMD) was exploited to treat alkaline CCCW for water reclamation and volume reduction. Results suggested that the alkaline CCCW can be concentrated to achieve high volume concentration factor. DCMD performance decline was primarily due to calcium carbonate (CaCO3) scaling. The CaCO3 deposited on the membrane surface was identified as calcite. Various strategies were adopted to mitigate membrane scaling. Acidization of the CCCW can effectively improve system performance. Additionally, the main scalant transformed from CaCO3 to calcium sulfate (CaSO4) with initial pH decrease. Physical cleaning using deionized water can effectively remove CaSO4 and restore DCMD performance. Compared with commercial antiscalants (sodium polyaspartic acid and amino trimethylene phosphonic acid), EDTA showed excellent scale-inhibition performance. The calcium and magnesium in the CCCW were efficiently pre-removed by chemical softening and ion exchange methods, resulting in improvement of DCMD performance. Given scale inhibition and chemical agent costs, chemical softening was the best strategy to alleviate membrane scaling. Our work suggested that DCMD can be selected as a promising approach for treating the high alkaline CCCW combined with proper strategies to control membrane scaling.

Synthesis of polyaspartic acid-capped 2-aminoethylamino acid as a green water treatment agent and study of its inhibition performance and mechanism for calcium scales

Polyaspartic acid (PASP), a well-known green scale inhibitor for industrial water treatment, might be decomposed with prolonged duration, and its anti-scaling performance against CaCO3 and CaSO4 is diminished at a low concentration (<10 mg L−1) and a high temperature. With semi-ethylenediaminetetraacetic acid (EDTA) tetrasodium salt as the mimicking model, novel phosphorus-free PASP-capped 2-aminoethylamino acid (PASP–ED2A) containing side chains bearing multi-functional groups is rationally designed and successfully prepared via the ring-opening reaction of cheap poly(succinimide) under mild reaction conditions with the assistance of readily available 2-aminoethyl amino acid. The static scale inhibition method is used to evaluate the scale inhibition performance of the as-synthesized PASP derivative. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy are utilized to monitor the crystallization process of calcium carbonate and calcium sulfate scales, and density functional theory calculations are conducted to shed light on the relationship between the molecular structure and scale inhibition mechanism of PASP–ED2A. Results show that the as-prepared PASP–ED2A shows better scale inhibition performance for CaCO3 and CaSO4 than PASP with a low concentration, a high temperature, and an extended duration. Particularly, PASP–ED2A with a concentration of 10 mg L−1 exhibits the best scale inhibition performance for CaCO3; its scale inhibition capacity is about two times as much as that of PASP. The reason lies in that the coordination atoms in the molecular structure of PASP–ED2A can chelate with Ca2+ to inhibit the combination of Ca2+ with anions and prevent the generation of CaCO3 and CaSO4 scales. The PASP–ED2A derivative can more efficiently retard the formation and growth of CaCO3 and CaSO4 crystal nuclei and exerts better inhibition performance against CaCO3 and CaSO4 scales than PASP.

Effect of the passive films on CaCO3 scale depositing on Q235 steel: Electrochemical and surface investigation

The deposition of the CaCO3 scale in circulating cooling water is a common and serious concern in the industry, which hinders the heat transfer, reduces water flow and blocks membrane filters. This paper aims at studying the effect of the γ-Fe2O3, Fe2(MoO4)3·γ-Fe2O3 and FePO4·γ-Fe2O3 passive films on CaCO3 scale deposition on Q235 steel by electrochemical methods, including linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) tests. The scale and corrosion inhibition performance of the passive films was evaluated by the residual current density (ir) and charge transfer resistance (Rct) values. Electrochemical results suggested that the passive films could inhibit corrosion and reduce the CaCO3 scale deposition on Q235 steel and the FePO4·γ-Fe2O3 complex passive film showed the best anti-scaling effect. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) tests showed that the passive films could lead to a decrease in the proportion of aragonite to calcite under cathodic water reduction conditions and the composition of the FePO4·γ-Fe2O3 complex passive film could deform the CaCO3 crystal.

Carboxyl or phosphate functionalization polyamidoamine dendrimer efficient scale inhibitor: Preparation and properties

Stringent water resources scarcity and severe environmental restriction requires environmentally friendly and efficient scale inhibitors exploitation. Functionalization of polyamidoamine dendrimers for scale inhibitor was performed using 2-phosphate-1, 2, 4-butane tricarboxylic acid (PBTCA) and succinic anhydride (SA). In this study, PBTCA modified polyamidoamine dendrimers (PAMAM-1), SA modified first and second generation polyamidoamine dendrimers (CAMAM-1 and CAMAM-2) are prepared. Static scale inhibition method is employed to assess the scale inhibition efficiency of linear low molecular polyacrylic (LPAA), PBTCA, PAMAM-1, CAMAM-1 and CAMAM-2 against CaCO3 and CaSO4. The results show that carboxyl terminated polyamidoamine dendrimers has excellent scale inhibition performance comparable to PBTCA and PAMAM-1. Compared to LPAA and PBTCA, dendritic structure can effectively improve the scale inhibition performance of the scale inhibitor. Furthermore, the scale inhibition performance enhances with increasing generation of carboxyl-terminated polyamidoamine dendrimer. The inhibition efficiency of CAMAM-2 against CaCO3 and CaSO4 is about 96.3% and 95.2% at a concentration of 10 mg/ L. Moreover, The CAMAM-2 performs above 85% scale inhibition at Ca2+concentration is 4000 mg/L and 90% scale inhibition at border pH 5–9. The FT-IR, XRD and SEM-EDX results show that the CaCO3 changes from stable calcite to metastable aragonite and vaterite, and the needle like structure of CaSO4 is destroyed to small crystals. CAMAM-2 only occupies the crystallization site and distorts the lattice of calcium scale in the crystal growth process rather than adsorb on the final crystal surface. This paper provides data support for the application of phosphate or carboxyl terminated polyamidoamine dendrimer in scale inhibition.

Simple spray method preparation of slow-release porous microcapsule for long-term active anti-corrosion and scale-inhibiting coatings

Anti-scaling is a key challenge in various industrial productions. The use of coatings is the most effective strategy for protecting metal equipment. An excellent scale inhibitor is 1-hydroxy ethylidene-1, 1-diphosphate (etidronic acid) (HEDP), which is usually incorporated into wastewater and discharged directly with the water flow. In this study, HEDP was coated with poly-α-ethyl cyanoacrylate (PEC) by a simple spray method. The corresponding slow-release microcapsules, which we named PEC&HEDP, were successfully prepared. In addition, a correct mass of the microcapsules was added to the spray polyurea elastomer (SPUA) coating. The resulting SPUA/PEC&HEDP70&30 composite coating exhibited excellent anti-corrosion and scale-inhibiting effects. Electrochemical impedance spectroscopy and salt spray corrosion test were used to assess the corrosion resistance of the coating. The results showed that the barrier performance of the composite coating improved significantly. In addition, the scale inhibition performance of the composite coating was tested in a supersaturated CaCO3 solution. The results showed that the scale inhibition rate of the composite coating was higher by as much as 80.5% relative to the pure SPUA coating. This work provides a new and simple method for designing and preparing a slow-release microcapsule composite coating intended for scale control.

Chitosan-acrylic acid-polysuccinimide terpolymer as environmentally friendly scale and corrosion inhibitor in artificial seawater

A biodegradable and non-phosphorus chitosan derivative (CTS-AA-PSI) was synthesized with chitosan, acrylic acid and polysuccinimide, which can be used as a new environmentally friendly scale and corrosion inhibitor. The structure of CTS-AA-PSI was confirmed by FTIR, 1H NMR and 13C NMR. The CTS-AA-PSI showed outstanding scale inhibition performance with a scale inhibition rate of 87.96% at the concentration of 25 mg/L. The electrochemical impedance results indicated that CTS-AA-PSI showed a significant corrosion inhibition effect in a 3.5% NaCl solution with a corrosion inhibition rate of 71.17% when the dosage was 500 mg/L. In addition, the biodegradability experiment showed that its degradation rate was 72.32% on the 28th day. It was demonstrated that the CTS-AA-PSI is a readily biodegradable material. The possible scale inhibition mechanism was explored by SEM, XRD, XPS and EEM. The results indicated that the excellent scale inhibition performance of CTS-AA-PSI was related to its chelating and lattice-distortion ability, which inhibited the formation and precipitation of CaCO3 crystal. These findings suggest that CTS-AA-PSI is a quite promising candidate for an environmentally friendly scale and corrosion inhibitor.

Nanosilica modified with polyaspartic acid as an industrial circulating water scale inhibitor

Given the special performance of nanosilica with its small size, large specific surface area and high surface activity, nanosilica containing reactive amino group (denoted as SiO2–NH2) and polysuccinimide were allowed to take part in polymerization reaction to afford SiO2–NH2 modified polyaspartic acid (denoted as SiO2–NH2/PASP), a potential polymer scale inhibitor with good water solubility for industrial circulating water. The scale inhibition performance of the as-prepared SiO2–NH2/PASP was evaluated by static scale inhibition test; and its scale inhibition mechanism was explored by means of scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Results indicated that SiO2–NH2/PASP exhibits excellent scale inhibition performance against CaSO4 and CaCO3 at very low concentrations (optimum scale inhibition rate of 100% and 68%, respectively), and the presence of 5 mg/L of SiO2–NH2/PASP greatly increases the inhibition efficiency of CaSO4 and CaCO3 scale by 21% and 53%, obviously higher than that of pure PASP.

Synthesis and Study of Modified Polyaspartic Acid Coupled Phosphonate and Sulfonate Moieties As Green Oilfield Scale Inhibitors

The petroleum industry has strived for several years to explore environmentally friendly scale inhibitors with no acute environmental impact. Well-known industrial biodegradable polyaspartic acid is widely used as a potent scale inhibitor (SI) against various inorganic scales in industrial circulating cooling water and topside petroleum applications. However, polyaspartic acid showed weak thermal stability at the petroleum reservoir temperatures. Here, we attempt to develop a new class of polyaspartic acid for squeeze treatment applications under harsh conditions. In this project, a series of modified polyaspartic acid, including pendant anionic functional moieties (phosphonate and sulfonate) were synthesized and investigated as new SIs to inhibit the calcium carbonate (calcite, CaCO3) and barium sulfate (barite, BaSO4) scales under oilfield conditions. These classes were synthesized via aminolysis of polysuccinimide with nucleophilic amine reagents under alkaline conditions. The products are polyaspartic acid-capped aminomethylene phosphonic acid (SI-2), polyaspartic acid-capped bisphosphonic acid (SI-3), polyaspartic acid-capped aminomethanesulfonic acid (SI-4), and polyaspartic acid-capped aminoethanesulfonic acid (SI-5), as well as in-house synthesized polyaspartic acid (SI-1). The scale inhibition activities of these compounds against carbonate and sulfate scales were determined using the dynamic scale loop test at 100 °C and 80 bar. Furthermore, the long-term thermal aging and calcium tolerance experiments were also investigated. It was found that polyaspartic-acid-capped aminomethylene phosphonic acid (SI-2) gave outstanding calcite scale inhibition performance and showed excellent thermal stability at 130 °C for 7 days compared to SI-1 and other modified SIs (SI-3-SI-5). This phosphonated polymer also exhibited superior calcium tolerance performance with Ca2+ ions up to 100 ppm, and moderate performance in the range of 1000–10 000 ppm calcium ions. This project highlights the success of designing and developing a new environmentally friendly calcite SI-based polyaspartic acid under harsh oilfield conditions.

Application of modified cellulose-based antiscalant in reverse osmosis membrane scaling control

<p indent=0mm>Applying membrane scaling is a key problem in reverse osmosis (RO) desalination processes. By dosing antiscalant, we can effectively inhibit inorganic scale and control RO membrane scaling. Accordingly, in this work, an environmentally friendly modified cellulose-based antiscalant is synthesized by the etherification of cellulose and subsequent graft copolymerization using the etherification product carboxymethyl cellulose (CMC), acrylic acid (AA), and sodium allyl sulfonate (SAS): CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS). The influence of molecular structure, CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) dose, and coexisting anions with respect to inhibiting the calcium-sulfate scale in the RO system are investigated. The results indicate that dosing CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) can significantly prolong the induction time of calcium-sulfate crystallization, inhibit the formation of calcium-sulfate scale, greatly alleviate both membrane fouling and membrane flux decline caused by membrane-surface scale formation, and effectively improve the membrane filtration efficiency. Static tests, scanning electron microscopy, optical microscopy, X-ray diffraction, conductivity measurements, and dispersion experiments suggest that the scale inhibition mechanism of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) can be attributed to the chelation and dispersion effects of the introduced anionic groups, and that the carboxyl groups are more efficient in the inhibition of calcium-sulfate scale than the sulfonic groups. In addition, an appropriate number of sulfonic groups on the graft chain of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS) can improve the water solubility of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS), as well as effectively stabilize the scale-formed substances and enhance the scale inhibition efficiency. If the proportion of sulfonic groups is too high, the content of the carboxyl groups decreases accordingly, which reduces the chelation and dispersion effects of CMC-<italic>g</italic>-P(AA-<italic>co</italic>-SAS), which, in turn, reduces the scale inhibition performance.

Evaluation of Arginine‐Modified Polyepoxysuccinic Acid as Anti‐scaling and Anti‐corrosion Agent

AbstractArginine‐modified polyepoxysuccinic acid (Arg‐PESA) was used as a scale inhibitor to study its anti‐scaling and anti‐corrosion performance. The existence of arginine groups enhances the adsorption and chelation of calcium substances, thus inhibiting the formation of a calcium scale. The effects of temperature, scale inhibitor concentration, pH, and calcium ion concentration on scale inhibition performance were studied. The morphologies and structures of the calcium scale and carbon steel coupons were observed and characterized by spectroscopic and microscopic methods. The interaction between Arg‐PESA and different crystal surfaces of calcium carbonate was simulated by molecular dynamics to elucidate the anti‐scaling mechanism. The addition of Arg‐PESA also significantly enhanced the dispersion of iron oxide.