Polymaleic Acid Research Articles

Hydrolytic polymaleic acid: An environmentally friendly inhibitor for the flotation separation of parisite from calcite and fluorite

Hydrolytic polymaleic acid (HPMA) was used as a highly selective depressant instead of water glass to achieve the flotation separation of parisite from calcite and fluorite. The inhibitory effect and mechanism of HPMA on fluorite and calcite was investigated using micro-flotation, zeta potential, contact angle measurements, adsorption measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and quantum chemical calculations. The results from single and artificially mixed minerals showed that parisite could be successfully separated from calcite and fluorite by using HPMA as a depressant. Further analysis revealed that HPMA chemically adsorbed onto the Ca2+ active sites of calcite and fluorite, forming a hydrophilic compound, Ca(COOR), which prevented the octyl hydroxamic acid (OHA) collector adsorbing on their surfaces. In contrast, HPMA only weakly physically adsorbed onto the surface of parisite, allowing it to maintain good floatability after conditioning with HPMA. Therefore, HPMA has a potential as an inhibitor for effectively separating parisite from fluorite and calcite in rare earth ore flotation process.

Mechanistic insights into flotation separation of galena and chalcopyrite with polymaleic acid as Pb-affinity depressant: Experiments and MD simulations

Utilization of novel and highly efficient organic depressants in separation of various minerals in flotation is always a research hotspot. Herein, polymaleic acid (PMA) was utilized as an eco-friendly depressant with high affinity for lead to effectively separate chalcopyrite from galena via the flotation method. Flotation trials showed that PMA, added at low dosages, could considerably depress galena, while chalcopyrite was minimally affected, thereby achieving the separation of both minerals. Adsorption tests indicated that PMA strongly and selectively adsorbed on galena than on chalcopyrite, which significantly reduced the reactive activity of xanthate on galena. These findings were supported by contact angle measurements. Surface properties investigations also corroborated the stronger adsorption of PMA observed on galena. Molecular dynamic simulations suggested that the introduction of PMA into an aqueous system resulted in the accumulation of water molecules on galena. Simultaneously, the adsorption strength of PMA on galena increased during the interaction process between PMA and galena. These effects altered the surface characteristics of galena and increased its surface hydrophilicity. The present work provides mechanistic insights into the separation of metallic sulfide minerals in the presence of organic acid via the flotation method.

Preparation of Nano-PbWO4 Particles by Polymaleic Acid Modification: A Highly Filled Nonwoven Membrane Used To Improve the Wearing Comfort and Radiation Safety of γ-ray Protection Products

Preparation of Nano-PbWO₄ Particles by Polymaleic Acid Modification: A Highly Filled Nonwoven Membrane Used To Improve the Wearing Comfort and Radiation Safety of γ-ray Protection Products

Comparative study of a low phosphorous co‐polymer inhibitor with commercial scale inhibitors used in cooling water systems

AbstractTo reduce the economic loss caused by scale formation and corrosion of equipment and pipelines, a low phosphorus polymer scale inhibitor is synthesized and characterized, the ability of the polymer to mitigate the calcium scale and the influences of operating conditions on CaCO3 scale are investigated by static tests. X‐ray diffraction (XRD) and scanning electron microscope (SEM) studies are performed to understand the morphological changes of the scales in the presence of the polymer. The interaction between polymer molecules and calcite crystal surface is studied by molecular dynamics simulation. The synthesized polymer is compared with the commercial product such as hydrolysis polymaleic acid (HPMA), polyacrylic acid (PAA), and 1‐hydroxy ethylidene‐1,1‐diphosphonic acid (HEDP). The experimental results show that the polymer shows better inhibition of calcium scale than the commercial product. The scale inhibition efficiency of the polymer is 92% at 10 mg/L for CaCO3 scale, 83% at 14 mg/L for Ca3(PO4)2 scale, and 98% at 6 mg/L for CaSO4 scale. SEM and XRD analysis show that the polymer induces the conversion of CaCO3 from calcite to arachite and crystal. The interaction of the polymer with both 104 and 1–10 calcite crystal surfaces are more stable than that of commercial product. The experimental results are in good agreement with those of molecular dynamics simulation.

Synergistic effects of polymaleic acid and di(dioctylpyrophosphato) ethylene titanate on B4C modification in highly filled polymer fibers for improved neutron protection safety and wear comfort of articles

Developing wearable articles with radiation protection safety and wear comfort is one of the urgent issues in that flourishing nuclear technologies are accompanied by increasing radiation threats. However, current wearable articles either display insufficient shielding performance or exhibit poor air and water vapor permeability, which are difficult to meet the growing demand of personal protection in nuclear environments. In this paper, polymaleic acid (PMA) and di(dioctylpyrophosphato) ethylene titanate (DPET) have been used to superficially modify boron carbide (B4C) particles for constructing sufficient hydrogen bonds with polyvinyl alcohol (PVA) matrix. Synergistic effects of PMA and DPET lead to enhanced interfacial interaction. As high as 55 wt% B4C/PVA fibers have been obtained with smooth wet spinning. Their multi-layered fabrics display excellent air and water vapor permeability meanwhile thermal neutron shielding. Three-layer B4C/PVA fabrics have 89.2 % thermal neutron (0.025 eV) shielding rate. In addition, 321.1 mm/s air and 2236.2 g/m2·24 h water vapor permeability have been measured. Besides, the fabrics still show great flexibility in spite of the fibers with extreme filling of inorganic particles. This work provides alternative wear articles to cope with the dilemma of radiation protection safety and wear comfort in neutron radiation environments.

Kilogram-Scale Synthesis of Extremely Small Gadolinium Oxide Nanoparticles as a T1-Weighted Contrast Agent for Magnetic Resonance Imaging.

Magnetic resonance imaging contrast agents are frequently used in clinics to enhance the contrast between diseased and normal tissues. The previously reported poly(acrylic acid) stabilized exceedingly small gadolinium oxide nanoparticles (ES-GdON-PAA) overcame the problems of commercial Gd chelates, but limitations still exist, i.e., high r2/r1 ratio, long blood circulation half-life, and no data for large scale synthesis and formulation optimization. In this study, polymaleic acid (PMA) is found to be an ideal stabilizer to synthesize ES-GdONs. Compared with ES-GdON-PAA, the PMA-stabilized ES-GdON (ES-GdON-PMA) has a lower r2/r1 ratio (2.05, 7.0 T) and a lower blood circulation half-life (37.51min). The optimized ES-GdON-PMA-9 has an exceedingly small particle size (2.1nm), excellent water dispersibility, and stability. A facile, efficient, and environmental friendly synthetic method is developed for large-scale synthesis of the ES-GdONs-PMA. The weight of the optimized freeze-dried ES-GdON-PMA-26 synthesized in a 20L of reactor reaches the kilogram level. The formulation optimization is also finished, and the concentrated ES-GdON-PMA-26 formulation (CGd=100mm) after high-pressure steam sterilization possesses eligible physicochemical properties (i.e., pH value, osmolality, viscosity, and density) for investigational new drug application.

Effect of polymaleic acid and microwave radiations on reverse osmosis membrane's performance and properties: A response surface methodology approach

Polymaleic acid was tested for its ability to control inorganic fouling in reverse osmosis (RO) system for the first time as a membrane surface modifier. Using the design of experiments (DoE) based on the response surface methodological (RSM) approach, the effect of polymaleic acid concentration and microwave radiation time duration was studied on the membrane permeation properties. Considering the objective of achieving maximum water permeance and salt rejection properties, the conditions of polymerization were optimized using RSM and experimentally validated in the lab. At the optimum conditions of 10 mg·L−1 polymaleic acid, and 27 s radiation time, the pure water permeance and salt rejection were 3.05 L·m−2·h−1·bar−1, and 97.8 %, respectively. The optimized membrane was characterized through microscopic and spectroscopic techniques. When tested for its performance under inorganic fouling conditions, the modified membrane demonstrated a negligible decline in permeate flux for 6 h, and no formation of calcium sulfate precipitates on the membrane surface. This research aims to promote the development, optimization, and application of dual-functional RO membranes that can control different types of membrane fouling.

Desalinization of degraded soils by atmospheric precipitation and Biosolvent for saving water resources

In the Syrdarya region of Uzbekistan, the influence of atmospheric precipitation on changes in the degree of salinity and chemical composition of the upper 30 cm soil layer was studied. Experiment options: 1 - loosening the soil to a depth of 70 cm, 2 - loosening, followed by soil treatment with preparation containing polymaleic acid. A decrease in the degree of soil salinity by 7 - 8 dS/m has been established with the help of only 302 mm of precipitation, without water wasted for leaching. The decrease in soil salinity was: according to EU, 56% - in option 2, and 52% - in option 1. According to TDS, the salinity reduction was: - 61 and 52%, according to SO “4. - 58 and 47%. The content of calcium in the variant with the use of Biosolvent decreased by 48%, and in the control variant, it increased by 15%. It has been estimated that with a decrease in salinity from 16 to 8 dS/m, a possible increase in the yield of a salt-tolerant barley crop by 1.6 t/ha is possible. Taking into account the costs of loosening and tillage with the preparation, the net income of the farmer can be $480/ha.

Stable Binding Conformations of Polymaleic and Polyacrylic Acids at a Calcite Surface in the Presence of Countercations: A Metadynamics Study.

Elucidating the stable binding conformations of additives at the surface of CaCO3 crystals is essential to biomineralization, scale inhibition, and materials technology. However, accomplishing this by experimental means is rather difficult. In this study, molecular dynamics simulations based on a metadynamics approach were conducted to elucidate the stable binding conformations of a deprotonated polymaleic acid (PMA) additive and two deprotonated poly(acrylic acid) (PAA) additives with different polymerization degrees in the presence of various countercations at a hydrated calcite (104) surface. The simulated free-energy surfaces suggested the existence of several slightly different stable binding conformations for each additive. The appearance of these distinct binding conformations is speculated to originate from different balances of interactions between the additive, the calcite surface, and the countercations. The binding conformations and binding stabilities at the calcite surface were affected by the countercations, with Ca2+ ions producing a more pronounced effect than Na+ ions. Furthermore, the simulation results suggested that the binding stability at the calcite surface was higher for the PMA additive than for the PAA additives, and the PAA additive with a polymerization degree of 10 displayed a binding stability that was similar to or lower than that of the PAA additive with a polymerization degree of 5. The present simulation method provides a new strategy for analyzing the binding conformations of complex additives at material surfaces, developing additives that stably bind to these surfaces, and designing additives to control crystal growth.

Effect of antiscalants on organic fouling potential of rough membrane in membrane distillation: Focusing on the evaluation of interfacial interaction

Impacts of antiscalants on fouling potential of rough membranes were explored in membrane distillation (MD) system, and three antiscalants were applied in this study, including 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), diethylene triamine penta methylene phosphonic acid (DTPMPA), and polymaleic acid (HPMA). Deteriorated organic fouling caused by 150 mg/L lysozyme (LYS) solutions was observed with the addition of antiscalants in MD influent, due to variations of surface properties induced by adhesion of antiscalants. In MD operation of LYS solutions, a mild flux drop of 37.7% was obtained for unmodified PTFE membrane, while PBTCA, DTPMPA, and HPMA groups all demonstrated severe flux decline of 58.4%, 46.4%, and 63.5%, respectively. Methods of surface element integration and extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory were applied to estimate interfacial interaction among foulants-reconstructed membrane surface. MD membranes initially adhered by PBTCA and HPMA both demonstrated higher surface roughness and correspondingly lower energy barrier, promoting sharper depositions of LYS and faster flux decline. A four-stage pattern was roughly proposed for organic fouling development in MD, which was notably affected by adherence of antiscalants. Comparatively, MD membranes adhered by DTPMPA displayed relatively lower surface roughness and higher interaction energy barrier, suggesting that DTPMPA might be a feasible method for MD fouling mitigation.

Zero liquid discharge treatment of brackish water by membrane distillation system: Influencing mechanism of antiscalants on scaling mitigation and biofilm formation

• The anti-scaling performance of PBTCA, DTPMPA, and HPMA in MD system was studied. • Regulation mechanism of antiscalant on the MD fouling layer formation was presented. • Usage of DTPMPA in MD existed the risk of phosphate crystals and membrane wetting. • HPMA was suitable for the long-term operation of zero-liquid discharge MD system. Membrane distillation (MD) is increasingly regarded as a promising technique for brine management and zero liquid discharge (ZLD) disposal of seawater and brackish water owing to its excellent effluent quality and higher salt tolerance. However, membrane fouling issues of MD, especially scaling, have been confirmed as a crucial challenge impeding its large-scale utilization. Presently, the scaling issue of conventional membrane-based desalination techniques including reverse osmosis (RO) and ultrafiltration (UF), has been effectively controlled via the usage of antiscalants. Hence, this work applied three representative antiscalants of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), diethylene triamine penta methylene phosphonic acid (DTPMPA), and polymaleic acid (HPMA) in MD devices to restrain the scaling of polytetrafluoroethylene (PTFE) membrane during the ZLD treatment of synthetic brackish water. Furthermore, influences of antiscalant presence on variations of feed water qualities and the corresponding biofilm formation were also comprehensively studied via the high throughput sequencing method of 16S rDNA and 16S rRNA as well as a confocal laser scanning microscopy (CLSM). Compared to DTPMPA (77.4%-97.8%) and HPMA (42.1%-97.8%), a higher anti-scaling efficiency was obtained for PBTCA (90.6%-98.1%) in MD system, while the membrane biofilm formed in PBTCA group exhibited a remarkable appearance of live cells (14.046 μm 3 /μm 2 ). The secondary fouling of phosphate scale and pore wetting might be induced by the utilization of DTPMPA in MD plants, sharply increasing the effluent conductivity to 176.4 μS/cm (12 d). Comparatively, HPMA could be largely combined with salt ions to form loose slags with good fluidity, promoting the reuse of MD membranes and the subsequent disposal of MD brine.

Morphology control of laser-induced dandelion-like crystals of sodium acetate through the addition of acidic polymers

Crystal growth speeds, crystal sizes and the morphology of sodium acetate (CH3COONa) crystals in the presence of polymaleic acid and polyacrylic acid with different concentrations were investigated in supersaturated solutions of sodium acetate. The technique of non-photochemical laser-induced nucleation (NPLIN) was used to produce initial crystallites of anhydrous CH3COONa. The anhydrous CH3COONa crystal growth in solution after laser irradiation resembled the formation of dandelion seed heads. Even though NPLIN could offer temporal–spatial control of crystal nucleation without the addition of acidic polymers, the crystal growth rates were heterogeneous for crystallites along the laser pathway, which led to irregular crystalline sizes and morphologies. Here, a controllable approach from crystal nucleation to crystal growth has been designed through the addition of acidic polymers in the laser-induced growth of anhydrous CH3COONa crystals. In the presence of an acidic polymer, both the crystal growth and the morphological modification were controlled from tuft-shaped crystals to dandelion-like crystals. As bulk solid thicknesses and crystal growth speeds can be modified by different mass fractions of acidic polymer, a mathematical model was established to analyse the dynamics of crystal growth under the effect of acidic polymers. The model reproduces remarkably well the experimental trend and predicts experimental results. The changes in supersaturation and the number of nuclei through the addition of acidic polymers were analysed to investigate the underlying mechanism of morphological difference.

Preparation of Ag NPs and Its Multifunctional Finishing for Cotton Fabric.

To explore the combination of silver nanoparticles (Ag NPs) prepared in a green manner with cotton fabrics and the washing durability of the fabric after the combination. In this paper, the natural material, honeysuckle extract, was used as a reducing agent to prepare the Ag NPs’ solution. The structure and size of Ag NPs were analyzed using ultraviolet–visible spectrophotometry (UV–vis), transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy characterization. The results showed that Ag+ was successfully reduced to Ag0 by the honeysuckle extract, the particle size was about 10.59 nm, and the potential was −42.9 mV, so it had strong electrostatic repulsion and good stability. Meanwhile, it was found that the synthesized Ag NPs were well coated by the honeysuckle extract, so they would not aggregate. Then, the cotton fabric was finished with Ag NPs’ solution by the dipping method using a complex of polymaleic acid (PMA) and citric acid (CA) as a cross-linking agent to fix Ag NPs on the cotton fabric. The structures of cotton fabrics before and after finishing were characterized using FT-IR, scanning electron microscopy (SEM), XRD, X-ray photoelectron spectroscopy (XPS), and thermogravimetric (TG) analysis, and the multifunctional properties of the finished cotton fabrics were explored by measuring the antibacterial rate, the wrinkle recovery angle (WRA), and the UV protection factor (UPF) value. The results show that Ag NPs were successfully loaded onto cotton fabric, and the PMA + CA compound was successfully cross-linked to the fabric. The cross-linked Ag NPs’ cotton fiber was rougher than that before cross-linking, and its TG stability improved. The PMA + CA compound fixed Ag NPs on the cotton fabric through chemical bonds, so it still had a 99% antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 50 washings. Compared with unfinished cotton fabric, the UPF value and WRA of the cross-linked Ag NPs cotton increased by 34.09 and 98°, respectively, and its color did not change much.

Microbially-induced mineral scaling in desalination conditions: Mechanisms and effects of commercial antiscalants

Reverse osmosis (RO) technology is promising in the sustainable production of fresh water. However, expansion of RO use has been hindered by membrane fouling, mainly inorganic fouling known as scaling. Although membrane mineral scaling by chemical means have been investigated extensively, mineral scaling triggered by microbial activity has been largely neglected.In this study, the simultaneous biomineralization of CaCO3 and CaSO4 in the presence of three different microbial communities from fresh water, wastewater, and seawater was investigated. In the presence of either 13 or 79 mM of Ca2+ and SO42- in the media, the fresh water microbial community produced calcite/vaterite and vaterite/gypsum, respectively; the wastewater community produced vaterite and vaterite/gypsum, respectively; and the seawater community produced aragonite in both conditions. The results showed that the concentration of salts and the microbial composition influence the types of precipitates produced.The mechanisms of crystal formation of CaCO3 and gypsum by these communities were also investigated by determining the need for metabolic active cells, the effect of a calcium channel blocker, and the presence of extracellular polymeric substances (EPS). The results showed that metabolically active cells can lead to production of EPS and formation of Ca2+ gradient along the cells through calcium channels, which will trigger formation of biominerals.The prevention of biomineralization by these consortia was also investigated with two common polymeric RO antiscalants, i.e. polyacrylic acid (PAA) and polymaleic acid (PMA). Results showed that these antiscalants do not prevent the formation of the bio-precipitates suggesting that novel approaches to prevent biomineralization in RO systems still needs to be investigated.

Development of dual quantum dots-based fluorescence-linked immunosorbent assay for simultaneous detection on inflammation biomarkers

Simultaneous detections of different but clinically relevant biomarkers are of extremely importance in biomedicine. Due to their unique photophysical properties, quantum dots (QDs) are ideally suited for highly sensitive multiplexed determination. Herein, a dual quantum dots-based fluorescence-linked immunosorbent assay (dQDs-FLISA) for simultaneous and quantitative detection of inflammation biomarkers (i.e. serum amyloid A (SAA) and C-reactive protein (CRP)) has been established. After being coated by amphiphilic oligomers (polymaleic acid n-hexadecanol ester, PMAH), the red-QD and green-QD with high quantum yields were used as fluorescence probes to couple SAA and CRP antibodies, respectively. Cross-reactivity among the SAA and CRP’s antibodies and antigens have been carefully examined by interference experiments, and it was successfully avoided by the specific probe adding sequence. Therefore, the assay provided a broad linear analytical range, including SAA quantitative range of 10–1,000 ng mL−1 with linear correlation (R2) of 0.992, and CRP quantitative range of 10–1,000 ng mL−1 with R2 of 0.998. The limit of detections (LODs) for SAA and CRP using dQDs-FLISA were 2.39 ng mL−1 and 6.37 ng mL−1, respectively. The accuracy of the assay has been confirmed with recoveries of 92.13%–101.85%. More importantly, the assay results showed good specificity, the QD-antibody probe could couple corresponding antigen (CRP or SAA) high-efficiently and it could be out of interference of other antigens and substances in serum. Given its good performance, the proposed dQDs-FLISA method offers great potential for simultaneous and quantitative detection of other biomarkers in in vitro diagnostic (IVD).

Effect of polymaleic acid on saline sodic soils

Saline-sodic soils in Middle Awash Valley area of Ethiopia have very high soluble sodium content and exchangeable sodium percentage (ESP). Leaching soluble salts with water alone could not fasten reclamation of these soils. Because all pore spaces of the soil were already sealed off with precipitated soluble salts; which retarded percolation of leaching water to the soil. Hence, Polymaleic acid was tested under controlled pot leaching under laboratory condition. The treatments were control (leaching with water only), 10, 20, 30 and 40ml polymaleic acid per kilogram of soil. Each treatment was replicated four times. As a result of leaching and polymaleic acid application to the saline - sodic soil, the ECe of the soil was was drastically reduced as the rate of polymaleic acid rate was increased. At the end of leaching, soluble cation and anions were also drastically decreased as compared to the control treatment. Hence, polymaleic acid soil conditioner could be used as an amendment for reclamation of high saline - sodic soils.

Spherulitic growth and morphology control of lithium carbonate: the stepwise evolution of core-shell structures

In this paper, we demonstrate morphologies, controlling factors (temperature, supersaturation and additives) and formation processes of lithium carbonate (Li2CO3) spherulites. Li2CO3 crystals were synthesized via a reaction crystallization and the effect of supersaturation was studied by changing temperature, adding antisolvent and altering Li+ ions concentration. Star-like and flower-like polycrystalline particles were produced without additives. By addition of sodium hexametaphosphate (SHMP), spherical particles could be obtained composed of radially arranged crystallites and core-shell structure was evolved at lower temperature. Time-resolved experiments were performed to detect the nucleation time and morphological changes. It was found that SHMP strongly inhibited nucleation and induced noncrystallographic branching. Two formation mechanisms were proposed to illustrate the stepwise evolution of core-shell spheres under different conditions. In addition, sodium tripolyphosphate exhibits similar effects with SHMP, while polymaleic acid modulates a different spherulitic growth mode. These findings provide new insights into spherulitic growth and fabrication of spherical particles.

RETRACTED ARTICLE: Formation of polyelectrolyte multilayer films with controlled wettability via layer-by-layer electric-assembly

Taking the positive charged poly (diallyldimethylammonium chloride), PDDA, and negative charged polymaleic acid, PMA, as raw materials, the polyelectrolyte multilayer film, PMF, with oppositely charged surfaces was prepared by the layer-by-layer electric-assembly, LBLEA, method. Experimentally, the applied voltage was varied and the electrostatic force, EF, was controlled in enhancement or reduction, respectively. Results showed that these PMFs have oppositely surface wettability because the PDDA surface was sensitively responded to the voltage increase with EF enhancement to form the hydrophobic C=C structure, and the PMA surface was oppositely sensitively responded to the voltage increase with EF reduction to form the hydrophilic Cl−–COOH structure, respectively. A related mechanism has been discussed by investigating the effect of voltage increase on the surface tension of these two polyelectrolyte solutions.

Synergetic Properties of Some Polymers with Antiscaling and Anticorrosive Action for Industrial Cooling Water Systems Protection

In this study, to examine synergistic effect of various combinations of the following polymers: PSO-1 (an oligomer phosphinosuccinic in neutralized state) and PMA-M1 (mixture by weight ratio 1/1 from 2-phosphonobutane-1-2, 4 tricarboxilic acid with polymaleic acid) were investigated as corrosion inhibitors for carbon steel of type OL 37, OLC 45 and for copper and brass. Using the microwaves energy, new polymers with antiscaling and anticorrosive properties were synthesized in microwaves field. These new polymers were obtained by radical polymerization of acrylic and/or acrylsulfonate water-soluble monomers in presence of microwaves field chain transfer agents, under the action of peroxidic initiators. The inhibitive properties of these organic compounds were analyzed by electrochemical measurements, FT-IR spectroscopy and by scanning electron microscopy (SEM) of the electrode surface. Also, a variety of short-time corrosion tests on laboratory scale were used to determine the performance and application parameters under different environmental conditions. The metallographic micrographies and scanning electron microscopy made before and after the potentiodynamic polarizations pointed out the evolution of the corrosion process. The inhibition activity analysis of the organic compounds was made by assuming that, the mechanism of inhibition by organic molecules is chemisorption and that the energetic of the corrosion process per se is unaffected by the addition of substituients on the parent compound. We presume that, these organic compounds inhibit corrosion of these materials by a protective mechanism, forming insoluble complexes and repairing the porous oxide layer. The addition of these new organic polymers offers protection by forming an adsorption organic barrier film at the electrode surface. The corrosion parameters obtained from polarization curves and from EIS spectra are in good concordance and point out the inhibitory action of these new organic polymers. The addition of the organic inhibitors led in all the cases to inhibition of the corrosion rate. The organic compounds used are adsorbed on the electrode surface according to a Langmuir isotherm. The inhibition process was attributed to the formation of the adsorbed film on the metal surface that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface The negative value of thermodynamic parameter like Gibbs free energy of adsorption indicates the spontaneity of adsorption process. Moreover, characterization utilizing FT-IR confirms the adsorption of inhibitors and the constitution of corrosion products on the materials surface. EIS and potentiodynamic polarization results demonstrate its corrosion protection capacity

Study on inhibitors' performance under the condition of high concentration ratio in MED system

Improving the concentration ratio to reduce the emission of concentrated brine is required in some desalination plants. However, scaling problem will be aggravated with higher concentration. In this study, scaling tendency was analyzed according to two indexes including the Langelier Saturation Index and the Ryznar Stability Index. Four kinds of inhibitors were analyzed. Their inhibition performance under the condition of high concentration ratio in MED system was studied by both static jar tests and experiments on a small-scale falling film evaporation apparatus. Results indicate that severe scaling problems would occur when high concentration ratio encounters high temperature. Under the experimental condition, for which the temperature was 70 °C and the concentration ratio was 2.5, the alkaline scales were calcium carbonate. No magnesium hydroxide was formed. Calcium sulfate began to appear and increase when the concentration ratio exceeded 2. All inhibitors showed controlling effect on scale formation. Inhibitor A with its main constituents of HPAA and polymaleic acid showed the best inhibition performance. Better inhibition performance was achieved with higher inhibitor dosage, but no obvious improvement was observed when inhibitor dosage exceeded 5.5 ppm. The present study is helpful to the MED system under the condition of high concentration ratio.