Polymaleic Acid Research Articles

Progressing the understanding of chemical inhibition of mineral scale by green inhibitors

Reducing the formation of inorganic deposits in processing industrial waters presents a challenge for desalination systems. Our topic of research progresses the understanding of scaling phenomena in seawater and the effects of green inhibitors.In order to understand the processes occurring at the liquid–surface interface, a procedure has been developed to follow in situ and in real-time the growth of scale particles in the micrometer size range and to quantify the effects of inhibitor on the crystal evolution. Experiments were carried out with a green additive, polymaleic acid, at a concentration of 1 and 4 ppm and with PPCA (commercial phosphonate inhibitor) used as inhibitor reference.On the one hand, results showed that polymaleic acid reduces the formation of scale by acting on the nucleation and growth process namely at a concentration of 4 ppm. In this paper a comprehensive description of the inhibitor/surface interactions will be presented. The role of the green additive in affecting the interface will be discussed in relation to the principal mechanisms by which the inhibitors function.

Partial molar volume of anionic polyelectrolytes in aqueous solution

In this work the partial molar volumes ( V ) of different anionic polyelectrolytes and hydrophobically modified polyelectrolytes (PHM) were measured. Polymers like polymaleic acid- co-styrene, polymaleic acid- co-1-olefin, polymaleic acid- co-vinyl-2-pyrrolidone, and polyacrylic acid (abbreviated as MAS- n, PA- n-K 2, AMVP, and PAA, respectively) were employed. These materials were investigated by density measurements in highly dilute aqueous solutions. The molar volume results allow us to discuss the effect of the carboxylic groups and the contributions from the comonomeric principal chain. The PAA presents the smaller V, while the largest V value was for AMVP. The V of PHM shows a linear relationship with the number of methylene groups in the lateral chain. It is found that the magnitude of the contribution per methylene group decreases as the hydrophobic character of the environment increases.

In vitro transdermal iontophoretic delivery of leuprolide under constant current application

Transdermal delivery of Leuprolide, a nonapeptide LHRH agonist, was studied using constant current iontophoresis to explore methods for improving iontophoretic efficiency and determine the feasibility of delivery of therapeutic doses of the drug. Universal buffer consisting of citrate, phosphate and borate was used to carry out in vitro permeation experiments with heat separated human epidermis at pH 4.5 and 7.2. In addition, the effect of substituting this buffer with a macromolecular electrolyte, polymaleic acid, on the drug flux and the transference number was studied. Current densities from 0.5 to 2.3 μA/cm 2 were used requiring moderate potential differences between 60 and 420 mV to be applied thus limiting irreversible epidermal membrane alterations. The rather high electrical resistance of the epidermis of the order of 200 kΩ cm 2 was related to the sub-physiological electrolyte concentration. Resistance was continuously monitored to guarantee barrier integrity of the membrane. The permeation rate increased linearly with the current density for the universal buffer and was at pH 7.2 almost double that at pH 4.5 despite the greater ionic valence of the drug at pH 4.5 compared to pH 7.2; this being because of the opposite direction of the electroosmotic flow at the two pH values. Drug transference number at both pH values was approximately 0.5%. Replacement of the universal buffer with polymaleic acid yielded higher drug permeation rates and increased its transference number at comparable pH. Transference number, however, was still approximately 1% at the highest current density, showing that concomitant ions from added electrolyte or extracted from the skin and the electrodes accounted for 99% of the total current. Further, transference number of the drug with polymaleic acid appeared to increase with current density. The fluxes obtained for both electrolyte systems with the present experimental arrangement could be extrapolated to deliver therapeutically relevant doses of the drug.

Ester Crosslinking Treatmen for Reducing the Fibrillation Tendency of Lyocell Fibers

Lyocell fibers have excellent properties, but they show a distinct tendency to fibrillate with wetting and mechanical stress. Chemical modification by esterification of these fibers could be a good means of solving this problem. A scanning electron microscopy analysis shows that treatment with polycar oxylic acids can effectively reduce the fibrillation tendency of lyocell fibers. A revised wet abrasion test method is used to measure fibrillation tendency. Wet abrasion time and mechanical property measurements reveal that fibers treated with 5-6% 1,2,3,4-butanetetra-carboxylic acid or 13-14% polymaleic acid exhibit satisfactory fibrillation resistance and mechanical properties.

Channel flow cell studies on the evaluation of surface pretreatments using phosphoric acid or polymaleic acid for calcite stone protection

The dissolution kinetics of surface-pretreated and weathered calcite was investigated in dilute acid using a channel flow cell with microdisk detection. Two pretreatments were studied, polymaleic acid and phosphoric acid. Treatment with polymaleic acid was shown to significantly passivate calcite but to a lesser extent than the phosphoric acid and the former coating was found to be less effective for protection of calcite from acid attack. However, treatment of calcite with phosphoric acid resulted in the passivation of calcite from acid attack which strongly inhibited dissolution, an effect that was enhanced even further after exposure to the environment.

Transfer of Eu (III) associated with polymaleic acid to Bacillus subtilis

The aim of this study is to contribute to the understanding of the distribution of Eu(III) between dissolved organic matter and microorganisms, and to investigate the effect of competitive ions such as Ca +2 on adsorption properties. Polymaleic acid (PMA), is used as synthetic organic matter, having similar properties as natural fulvic acid, and Bacillus subtilis is chosen as microorganism. A double labeling method was used: [ 14C]MPA and 152Eu to quantify the behavior of the various components. Preliminary experiments showed that the adsorption of polymaleic acid onto Bacillus subtilis was negligible at pH=5 in 0.15 mol/l of NaCl. In the absence of Ca +2, the transfer of Eu(III) from PMA to B. subtilis could be described by a simple empirical model based on data obtained from sorption isotherms on the reference systems Eu(III)/PMA and Eu(III)/ B. subtilis. In the presence of Ca +2, the transfer was increased. The hypothesis that Ca +2 ions acted as a bridging agent between PMA and the bacteria was proposed.

Complexation studies of Eu(III) with alumina-bound polymaleic acid: effect of organic polymer loading and metal ion concentration.

To contribute to the comprehension of the metal ion sorption properties in mixed mineral-organic matter systems, interaction studies between Eu(III) and polymaleic acid (PMA)-coated alumina colloids were carried out at pH 5 in 0.1 M NaClO4. The studied parameters were the metal ion concentration (1 x 10(-10) to 1 x 10(-4) M) and PMA loading on alumina (gamma = 10-70 mg/g). The data were described by a surface complexation model. The constant capacitance model was used to account for electrostatic interactions. The results showed thattwo sites were necessary to explain the sorption data. At high Eu loading, Eu is surrounded by one carboxylate group and one aluminol group. The existence of this ternary surface site was in agreement with time-resolved laser-induced fluorescence spectroscopy measurements. At low metal ion concentrations, a surface site corresponding to a 1:1 Eu/COO-stoichiometry was deduced from modeling. Spectroscopic data did not corroborate the existence of this latter site. This discrepancy was explained by postadsorption kinetic phenomenon: a migration of the metal ion within the adsorbed organic layer.

Complexation and luminescence spectroscopic studies of europium(III) with polymaleic acid

Summary The complexation behavior of europium(III) with polymaleic acid (PMA) was studied at pH 5 in 0.1 M NaClO4 by anion exchange (AE). The concentration range investigated was from E-9 M to E-4 M for the europium ion and from 1 to 50 mg/l for the polymer. The quantitative description of experimental data showed the formation of a 1 : 1 Eu : PMA complex and the existence of at least two distinct interaction environments ("sites") of Eu with the polymer chain whose proportions varied with the ratio between total Eu and PMA concentrations. The existence of different sites was further demonstrated by Time Resolved Laser-induced Fluorescence Spectroscopy (TRLFS) measuring the lifetimes and emission spectra of EuPMA complexes. By using empirical relationships, environments implying 1 : 2 and 1 : 1 Eu : COO− coordination could be deduced. The results show similarities with published data obtained for fulvic and Aldrich humic acids as far as complexation properties at pH = 5 are concerned.

The Effect of Surface Pretreatment with Polymaleic Acid, Phosphoric Acid, or Oxalic Acid on the Dissolution Kinetics of Calcium Carbonate in Aqueous Acid

The kinetics of calcite dissolution in aqueous acidic solution following various surface treatments was investigated using the channel flow cell method with microdisk electrode detection. Pretreatment of calcite with solutions of polymaleic acid, phosphoric acid, or oxalic acid for up to 24 h is shown to provide protective coatings over the calcite, which substantially reduces further acid attack on the surface. Quantitatively each pretreatment was found to lead to a rate constant for proton-induced calcite dissolution of as low as 0.003 cm s−1, an order of magnitude less than that observed for untreated calcite, 0.035 cm s−1 at 21°C.

Role of chemical constituents in recycle brine on the performance of scale control additives in MSF plants

To combat the scaling problems in multistage flash (MSF) desalination plants, either mineral acids or scale control additives (SCAs) are used. Scaling phenomena from acid is controlled by adjusting pH and total alkalinity and requires stoichiometric amounts while SCAs act non-stoichiometrically by threshold effect or crystal distortion effect. Antiscalant dose rates in brine are found to vary from plant to plant. Efficiency of SCA could be influenced by its chemical nature, plant configuration and design, heat transfer rates and its surface and antiscalant reaction with brine constituents. The study was carried out to understand the varied dose rate and the role of some of the brine chemical constituents on the efficiencies of antiscalants. Experiments conducted with a bench-top system by simulating the MSF conditions at 95°C with brine and performance of SCA were evaluated using the threshold effect technique. Performance or efficiency of two SCAs, viz., polyphosphonate based (PPN) and polymaleic acid based (PMA) were evaluated in the presence of traces of copper, chromium, nickel, molybdenum and iron, which are present in the brine as corrosion products. Effects of humic substances, particulates, and chlorine which is used as biocide, are also evaluated. Results of bench-top studies revealed that Cu, Fe, and Cr do have a detrimental effect on the performance of two SCAs (PPN and PMA), while Mo and Ni do not have an adverse effect. Humic substances and particulates also do not have significant effect. However, chlorination of SCA does reduce the performance of SCA.

Piezoresonance sensor for ammonia with polymaleic acid as the sensitive coating

Results of the study of a piezoresonance sensor with polymaleic acid as the sensitive coating for the determination of the concentration of ammonia in air are presented. The influence of the mass of the polymer coating, the flow rate of the carrier gas, and relative humidity on the performance characteristics of the sensor was studied. The mechanism of the interaction of ammonia with the sorbent in the presence of water vapors is proposed based on experimental data and quantum chemical calculation. It is found that the sensor exhibits high selectivity for ammonia in the presence of vapors of saturated and aromatic hydrocarbons. The detection limit for ammonia at the humidity 45–55% is 0.04 mg/m3, which makes it possible to determine ammonia at a level of the maximum permissible concentration for inhabited areas; the concentration characteristic of the sensor is linear in the concentration range 0.04-40 mg/m3.

The performance of different anti-scalants in multi-stage flash distillers

The Saline Water Conversion Corporation (SWCC) of Saudi Arabia is an internationally recognized authority on scale control in multi-stage flash (MSF) distillers. This international recognition came about as a result of many years of work on this topic. There are publications of SWCC on MSF scaling phenomena over the past couple of decades. During the last decade, there was a monumental growth in SWCC's installed MSF plant capacities. The majority of SWCC MSF distillers were designed to operate with the additive scale control method rather than the previously predominant method of carbonate depletion through chemical reaction with sulfuric or hydrochloric acid. The Research and Development Center (RDC) in Al-Jubail has been involved during the last 3 years in the evaluation of available commercial scale inhibitors. Eight tests have been carried out at the RDC MSF pilot plant, Jeddah Phases III and IV and Al-Jubail Phase II to evaluate the effectiveness of three anti-scalants. These tests by anti-scalant types and places are (1) polycarboxylates in Al-Jubail II, RDC pilot plant and Jeddah IV; (2) polymaleic acid in Jeddah IV and RDC pilot plant; and (3) polyphosphonate in Jeddah III and the RDC pilot plant. This paper presents qualitative and quantitative performance results of three different anti-scalants. The threshold effect of these anti-scalants was tested on laboratory scale. In pilot and commercial plants the variation of the fouling factor with time was examined and quantified. The evaluation tests conducted on the commercial plants revealed that all the examined anti-scalants were successful in inhibiting alkaline scale formation and improving plant performance at a top brine temperature ranging between 105 and 110°C and with respective dosing rates of 1.5 and 3.0 ppm.

Effect of various forms of iron in recycle brine on performance of scale control additives in MSF desalination plants

Scale control additives (SCA) or antiscalants are used in multistage flash desalination plant to prevent fouling problems. Effective dose rates of some of these SCA are found to vary from plant to plant. Efficiency of antiscalants could be influenced by its chemical nature, plant configuration and design, heat transfer rate and its surface and antiscalant reaction with brine constituents. To understand the variation in concentration of SCA and effect of brine constituents on efficiency of SCA, some bench top experiments at 95°C with brine were conducted using the threshold effect technique. Two SCA, a polyphosphonate based (PPN) and polymaleic acid based (PMA) were used for these evaluations. The effect of Fe 3+, Fe 2+, Fe 2O 2. Fe(OH) 3, and rust on efficiency of SCA was determined. The threshold effect method, which measures the total alkalinity and calcium content of supernant to evaluate efficiency of SCA, was found to be an effective technique. Recycled brine constituents and corrosion products, especially Fe and its various chemical forms affect the efficiency of SCA at 2 ppm concentration and at 95°C in 1.4 times concentrated seawater brine. Various chemical hydrated and hydroxylated forms of Fe present in brine, viz., Fe 3+(H 2O) 6, Fe(OH) 3, Fe 2+, Fe 2O 3, rust, etc., all showed detrimental effect on efficiency of SCA. Among all the species of iron, Fe(OH) 3, reduced the efficiency of SCA by maximum of 40%. Among the two antiscalants, PPN showed 10–12% better efficiency in the presence of various iron species compared to PMA under similar bench top experimental conditions. The effect of brine constituents on PMA was more pronounced compared to PPN perhaps due to better complexing ability of the former.

Reductive Transformation of Dioxins: An Assessment of the Contribution of Dissolved Organic Matter to Dechlorination Reactions

The susceptibility of dioxins to dissolved organic carbon (DOC)-mediated dechlorination reactions was investigated using 1,2,3,4,6,7,9-heptachlorodibenzo-p-dioxin (HpCDD), Aldrich humic acid (AHA), and polymaleic acid (PMA) as model compounds. The dechlorination yields were on the order of 4−20% which, when normalized to phenolic acidity, was comparable to yields observed in the presence of the humic constituents catechol and resorcinol. Based on the ratio of dechlorination yields as a function of phenolic acidity and electron transfer capacity, differences in electron transfer efficiency to dioxins are likely combined effects of specific interactions with the functional groups and nonspecific hydrophobic interactions. Hexa- and pentaCDD homologues were dominant in all incubations, and diCDD constituted the final product of dechlorination. The rates of appearance of lesser chlorinated products (pM-nM/d) were similar to those observed in sediment systems and followed thermodynamic considerations as they decreased with a decrease in level of chlorination. Generally, both absolute and phenolic acidity-normalized rate constants for AHA-mediated reactions were up to 2-fold higher than those effected by PMA. These results indicate that the electron shuttling capacity of sediment DOC may significantly affect the fate of dioxins, in part through dechlorination reactions.

Utilização de água salina e condicionador de solo na produção de beterraba no semi-árido brasileiro

O experimento foi conduzido no Campo Experimental da Embrapa Semi-Árido em Petrolina - PE, no primeiro semestre de 1997 com o objetivo de avaliar o efeito de diferentes níveis de salinidade da água de irrigação e do condicionador de solo Sper Sal (ácido polimaléico) na produção de beterraba (Beta vulgaris L.), cultivar Early Wonder. O delineamento experimental foi de blocos ao acaso com quatro repetições. Os tratamentos foram: água com condutividade elétrica de 0,1 (água do Rio São Francisco - testemunha) 4 e 8 dS/m e água com condutividade elétrica 0,1, 4 e 8 dS/m mais Sper Sal, com parcelas de 2 m². Os resultados obtidos mostraram que as produtividades variaram de 20,2 a 65,4 t/ha para os tratamentos irrigados com água salina mais Sper Sal e água do Rio São Francisco, respectivamente. Não se verificou diferença significativa na produtividade quando do uso de água com níveis de salinidade de 4 e 8 dS/m, cujas produtividades foram 29,4 e 26,3 t/ha respectivamente. Nos tratamentos com Sper Sal, observou-se que na concentração salina de 4 dS/m, o condicionador de solo demonstrou ser mais eficiente, em relação à concentração de 8 dS/m.

Formaldehyde-free Durable Press Finishing Based on Polymaleic Acid Chemistry

Cross-linking mechanisms are discussed with thermal analysis and FTIR data suggesting that the wrinkle-resistant effects produced by polymaleic acid result from formation of ester bonds, via cyclic anhydrides. The characteristics of polymaleic acid resins are outlined, using molecular modelling to demonstrate their potential to penetrate cotton fibres and form multiple crosslinks. The persistence of these bonds through multiple wash cycles is investigated. The CROSSLINK cotton-finishing system is based on polymaleic acid chemistry and trial data are used to show that this formaldehyde-free technology produces wrinkle-resistance/durable press performance comparable with DMDHEU, together with significantly enhanced secondary properties.

Studies of nanoparticulate cadmium sulfide in amphiphilic polymaleic acid octadecanol ester Langmuir-Blodgett films

The reversed micelles of CdS nanoparticles capped with oligomer–polymaleic acid octadecanol ester (PMAO) were synthesized by a colloid chemical method in an aqueous system. The chemical ratio of PMAO between the carboxylic group and the hydrocarbon chain was controlled to 1.5 : 1. The PMAO-capped CdS nanoparticles were transferred on to CaF 2 and Si substrates by the Langmuir–Blodgett (LB) technique. Surface pressure–area isotherms indicated that PMAO-capped CdS nanoparticles could form a stable monolayer on the water subphase. The measurement of FTIR and small angle X-ray diffraction showed that the reversed micelles of PMAO-capped CdS nanoparticles were formed with a uniform size and order in LB films. The photoluminescence properties of PMAO-capped CdS both in the solution and in the LB film indicated that the photoluminescence peaks of reversed micelles obviously changed as a result of the energy transfer from PMAO to CdS and the interaction between clusters.

Preparation and structure of quantum-sized cadmium sulfide grown in amphiphilic oligomer Langmuir–Blodgett films

An amphiphilic oligomer, polymaleic acid with octadecanol ester (PMAO), with ratios of 2:1, 3.7:1 and 6:1 between the carboxylic groups and the hydrocarbon chains, was synthesized and has been used as a matrix to form and grow quantum dot-sized CdS particles. The formation of quantum-sized CdS particles during exposure of Langmuir–Blodgett (LB) films of CdPMAO to hydrogen sulfide has been studied using Fourier transform infrared spectroscopy and UV-vis absorption spectra. This showed that hydrogen bonding of the PMAO molecules were replaced by the metal ion (Cd 2+) bridges to form the bridging complex structures before the reaction with H 2S. The intensities of the asymmetric ν a(COO −) and symmetric ν s(COO −) stretching modes were reduced after the reaction. But the presence of the asymmetric ν a(COO −) and symmetric ν s(COO −) stretching mode in spectra implied that not all the CdPMAO oligomers in the film were converted to PMAO after exposure to H 2S gas. The result from the UV-vis absorption spectra indicated that the CdS within PMAO LB films showed a larger blue shift of the optical absorption edge with the decrease of the ratio between the carboxylic groups and the hydrocarbon chains. Moreover, it could be deduced that the size of the aggregate of the sulfides within PMAO LB films was smaller than that formed in stearic acid LB films.

Formation of Branched Fractal CdS Patterns in Oligomer LB Monolayers: A Study Using Transmission Electron Microscopy

Transmission electron microscopy images of the treelike fractal aggregates of CdS nanoparticles in amphiphilic oligomer (polymaleic acid with octadecanol ester) LB matrix were observed. The features of these aggregates were developed into the micrometer regime. By changing the ratio between carboxylic groups and hydrocarbon chains, as well as the surface pressure, different fractal CdS patterns could be obtained. These results lead us to propose the mechanism of the formation of branchlike patterns, very much analogous to two-dimensional irreversible fractal-growth models such as diffusion-limited aggregates (DLA). Weak hydrophobic and hydrophilic interaction for interfacial molecular recognition at the organic/inorganic interface had been proposed as providing a possible elucidation for the formation of some aspects of a self-similar fractal-like pattern. At a ratio of 7:1, the fractal dimension was calculated by the box-counting method, and the dominant value was 1.69 ± 0.03, which was in good agreement with two-dimensional DLA.

EFFECTS OF ORGANIC ACIDS ON SALT PRECIPITATION IN DRIP EMITTERS AND SOIL

Three organic acid compounds were evaluated for preventing precipitation of salts and/or removing salts indrip irrigation systems and soils. Three experiments were conducted to measure drip emitter clogging, ponded infiltrationand soil salinity change. All acid compounds included maleic acid, a form of dicarboxylic acid. The first organic acid wascomposed of polymaleic acid, maleic acid, surfactant blend, and inert ingredients. The second was an anionic polymerwith maleic acid as the organic acid. The third included a soap and was a 1:1 stoichiometric equivalent of an organiccarboxylic acid and an amine base. The first and third organic acid significantly reduced drip emitter clogging comparedto a water-only treatment. The third organic acid was significantly better than the first for reducing clogging. The thirdorganic acid and water-only treatments significantly reduced soil sodicity below the drip irrigation laterals during thestudy. Ponded infiltration tests with organic acid in water were also conducted. All three organic acid treatments producedsignificantly lower infiltration rates than the water-only treatment. This may have occurred because salt precipitates inthe soil were removed and pores were clogged.