Liquid-phase Polymer-based Retention Research Articles

Comparative Study of the Removal Efficiency of Nalidixic Acid by Poly[(4-vinylbenzyl)trimethylammonium Chloride] and N-Alkylated Chitosan through the Ultrafiltration Technique and Its Approximation through Theoretical Calculations.

Emerging antibiotic contaminants in water is a global problem because bacterial strains resistant to these antibiotics arise, risking human health. This study describes the use of poly[(4-vinylbenzyl) trimethylammonium chloride] and N-alkylated chitosan, two cationic polymers with different natures and structures to remove nalidixic acid. Both contain ammonium salt as a functional group. One of them is a synthetic polymer, and the other is a modified artificial polymer. The removal of the antibiotic was investigated under various experimental conditions (pH, ionic strength, and antibiotic concentration) using the technique of liquid-phase polymer-based retention (LPR). In addition, a stochastic algorithm provided by Fukui's functions is used. It was shown that alkylated N-chitosan presents 65.0% removal at pH 7, while poly[(4-vinylbenzyl)trimethylammonium chloride] removes 75.0% at pH 9. The interaction mechanisms that predominate the removal processes are electrostatic interactions, π-π interactions, and hydrogen bonding. The polymers reached maximum retention capacities of 1605 mg g-1 for poly[(4-vinylbenzyl) trimethylammonium chloride] and 561 mg g-1 of antibiotic per gram for alkylated poly(N-chitosan). In conclusion, the presence of aromatic groups improves the capacity and polymer-antibiotic interactions.

Removal of lithium ions from aqueous solutions by an ultrafiltration membrane coupled to soluble functional polymer

In this research, the separation and concentration of lithium ions (Li+) from the aqueous solution was studied by the liquid-phase polymer-based retention technique (LPR) using poly(sodium styrene sulfonate) (PSSNa), poly(potassium sulfopropylacrylate) (PSPAK) and poly(sodium acrylate) (PAS). These polymers were characterized by Fourier transform spectroscopy and thermogravimetric analysis, corroborating their correct formation. In addition, the ability to remove Li+ from water was studied, as a function of the amount of polymer, the pH of the solution and the initial concentration of Li+. The study of isotherms and the removal of Li+ in the presence of interferents was also carried out. Finally, the reuse of the polymer was evaluated in consecutive adsorption–desorption cycles.Based on the obtained results, it was determined that a polymer: metal molar ratio of 20: 1 at pH 5.7, was the most suitable for use in the LPR process. A Li+ removal efficiency (% R) of more than 80% was obtained. Among the polymers studied, PSPAK is the water-soluble polymer with the highest % R of Li+ and it achieves adequate permeation flux during LPR experiments (43.2 L h-1m−2). The experimental data obtained from the removal of Li+ were better adjusted to the Freundlich isothermal model. On the other hand, using 1:20Li+:interfering ion molar ratio, the Li+ removal efficiency of the LPR process decreases to 40% for Na+ or K+ and decreased to 20% for Mg2+ interfering ions. The polymer can be reused up to the fourth consecutive cycle, reaching a removal efficiency of 46%.

BIOPOLYMERS APPLIED TO REMOVE METAL IONS THROUGH ULTRAFILTRATION. A REVIEW

This manuscript is an overview of the versatile biopolymer materials alginic acid, carboxymethyl cellulose, and quaternized chitosan which contain different functional groups to remove hazardous inorganic species. These bioadsorbents are completely water-soluble and have a high versatility to achieve a higher sorption capacity and efficiency under different experimental conditions in combination with ultrafiltration membranes through the liquid-phase polymer-based retention (LPR) technique. In general, thesebioadsorbents are friendly with the environment and have a higher biodegradability compared with those more employed synthetic polymers.

N-Alkylated chitosan coupled to the liquid-phase polymer-based retention (LPR) technique to remove arsenic (V) from aqueous systems

Water-soluble polymer based on alkylated chitosan with a quaternary ammonium group (Ch-QAG) was prepared, characterized, and applied to remove arsenate ions from aqueous solution by LPR technique. The arsenic removal was performed by the washing method (WM) and enrichment method (EM). Through the WM, studies of the pH and variation in the concentrations of interferents and arsenate ions were carried out. The effect of the removal of arsenate ions in simulated water was determined from the Camarones River in northern Chile. Ch-QAG showed high affinity for binding arsenate species (99% of removal) at pH 11.0 at a molar ratio of 20:1 polymer: As(V). High selectivity was also observed in the presence of interfering ions such as Cl−, SO42-, and PO43-, resulting in a removal rate over 80% at percentages over 95% for a concentration of 100 mg L-1 of As (V). The maximum retention capacity obtained was 112, 105, and 98 mg g-1 for three load cycles. The retention percentage for simulated water was 46.3% at a concentration of 1300 μ g L-1. In conclusion, the results presented in this study show that using Ch-QAG with ultrafiltration membranes is a great alternative to remove As (V) at high removal rates.

Removal of chromium ions by functional polymers in conjunction with ultrafiltration membranes

Abstract In the current research water-soluble functional polymers (WSFP) were prepared via radical polymerization and purified by fractionation through ultrafiltration membranes with different molecular weights cut off (MWCO) of 30 and 100 kDa. The WSFPs were poly(3-acrylamide propyl) trimethyl ammonium chloride, P(ClAPTA), poly(2-acrylamido-2-methyl-1-propane sodium sulfonate, P(AMPSNa), and poly(3-methacrylamino propyl) dimethyl 3-sulfopropyl ammonium hydroxide, P(HMPDSPA). These polymers were characterized by Fourier transformed infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA). Using liquid-phase polymer-based retention technique (LPR), chromium [Cr(III) and Cr(VI)] retention was studied as a function of pH, polymer and chromium concentration, selectivity, maximum retention capacity, chromium elution capacity, and polymer regeneration through sorption and desorption studies. Results of FT-IR showed the characteristic absorption bands of the synthesized polymers. The decomposition temperatures of P(ClAPTA) were at 303.1 °C, and for P(AMPSNa) three decompositions temperatures were registered at 190.5 °C, 223.2 °C, and 304.8 °C. P(HMPDSPA) presented two important decomposition temperatures at 292.4 °C and 391.7 °C, respectively. Concerning to the retention of Cr(VI), it was maximal (100 %) when P(ClAPTA) was studied at pH 6. The maximum retention of Cr(III) (100 %) was achieved by P(AMPSNa) at pH 3. The optimum polymer:Cr mole ratio obtained was 10:1 for both Cr(VI) and Cr(III). The retention of Cr(VI) decreased due to the presence of interfering ions, and the hydrodynamic flow was almost constant during the ultrafiltration of polymer-Cr macromolecule.

Tetracycline removal by polyelectrolyte copolymers in conjunction with ultrafiltration membranes through liquid-phase polymer-based retention

In this study, we used a liquid-phase polymer-based retention technique assisted by polyelectrolyte copolymers containing quaternary ammonium and sulfonate groups that are capable of removing the antibiotic tetracycline (TC) through electrostatic interactions. The polymers were synthesized using zwitterionic, anionic, and cationic monomers with the aim of obtaining copolymers with different charge balances at the ratios of 1:1, 2:1, and 1:2 (negative: positive). The parameters investigated for each copolymer included the pH, ionic strength, concentration of polymer, maximum retention capacity, and sorption–elution process at pH 11.0 and 3.0. The copolymers with a charge ratio of 1:2 achieved the highest retention (80.0%) at alkaline pH, while the copolymers with charge ratios of 2:1 and 1:1 exhibited the maximum retention (72.0%) at acidic pH. Based on these results, the pH and charge of the polyelectrolyte copolymers play important roles in the TC removal processes. Additionally, the maximum retention capacity (MRC) recorded was 731.2, 176.8, and 214.8 mg TC/g of copolymer in the first charge for the three copolymer polyelectrolytes, and the second charge of the MRC process did not improve compared with the first load.

Conformational Stability Effect of Polymeric Iron Chelators.

SummaryThe design and synthesis of metal chelators with extraordinary metal affinities is a basic and challenging scientific problem of both fundamental and practical importance. Here, we demonstrate a “conformational stability effect” that can significantly enhance the metal affinity of ligands after conjugation to polymer chains with the ability to spontaneously adopt a specific conformation as an optimal “soft” scaffold to ensure maximum thermodynamic stability of the metal complexes. Using iron chelators as models, we show that simple conjugation of small molecule catechol ligands to a polyallylamine chain resulted in more than 8–9 orders of magnitude enhancement of the iron-binding affinity, which is comparable to that of enterobactin, the strongest iron chelator ever known. This study demonstrates that flexible polymer chelators may realize the highest possible metal affinities of the conjugated ligands owing to their ability to achieve an optimal conformation, which could advance the identification of strong metal chelators.

Application of the liquid-phase polymer-based retention technique to the sorption of molybdenum(VI) and vanadium(V)

This research is focused on molybdate and vanadate removal from aqueous solutions by the liquid-phase polymer-based retention (LPR) technique. In this technique, a cationic water-soluble polymer based on the ammonium quaternary group poly(diallyldimethylammonium chloride), PDDA, was used as a polymeric sorbent, and a regenerated cellulose ultrafiltration membrane was used as a filter. The removal of molybdenum and vanadium using the LPR technique was analyzed by both the washing and enrichment methods. The removal experiments using the washing method were conducted by varying the pH, polymer/metal molar ratio, concentration of metal ions, pressure and presence of interfering ions. In addition, the enrichment method was used to determine the maximum retention capacity of PDDA. The obtained results showed the highest retention capacity of molybdate (100%, using 30 mg/L in the feed) for PDDA at pH 3 and 9. The optimum molar ratio was 20:1 polymer/Mo(VI). The efficient vanadate retention (approximately 90%) was obtained at pH 6 with 10:1 polymer/V(V) molar ratio. The effect of metal concentration on the retention showed a higher retention of Mo(VI) independent of its concentrations. In the case of V(V), the maximum retention was reached when 60 mg/L of vanadium was used in the feed. The enrichment method showed the maximum retention capacities of 370 mg Mo(VI)/g PDDA and 520 mg V(V)/g PDDA. The presence of interfering ions did not affect the retention capacity of PDDA. These results showed that the combination of PDDA with ultrafiltration membranes could represent an alternative method for the removal of molybdate and vanadate from water.

Cytotoxicity and biodistribution studies on PEGylated EDA and PEG cored PAMAM dendrimers

Starting from Ethylenediamine (EDA) or poly(ethylene glycol) tetra amine (4-arm-PEG) cores, two different peripheral methylester (–COOCH3) or amine (–NH2) PAMAM dendrimers have been synthesized. In the growth phase of dendrimers, two important building blocks, methyl acrylate for the half generation and EDA for the full generations, have been used. In order to improve the yield and decrease the time for the aminolysis step, a microwave-assisted technique was applied. Both of these dendrimers with different cores were grown up to 4.5 generations where surface modification, i.e. PEGylation, with 10% Poly(ethylene glycol) bis(amine) was performed. In order to increase the solubility of dendrimers, esteric surfaces were converted to carboxylic acid groups. Accordingly, the dendrimers were soluble in water or in water–methanol mixture which enabled their purification by liquid-phase polymer-based retention in each step. Finally, the resulting products that were characterized with (NMR and FTIR) spectroscopy were evaluated in vitro and in vivo. The analytical grade dendrimers were not cytotoxic to mouse fibroblasts and their biodistribution was mainly determined in the site of injection (peritoneum), liver and kidneys.

Quaternised chitosan in conjunction with ultrafiltration membranes to remove arsenate and chromate ions

A sample of N,N,N-trimethylchitosan chloride (TMC) was prepared and its ability to remove arsenate and chromate from an aqueous solution was evaluated. The removal capacity was quantified by a liquid-phase polymer-based retention system. A washing method was used to determine the effect of pH, molar ratio, contact time, and interfering ions on the removal of the anions. The results showed that TMC exhibits a high affinity for the divalent species HAsO42− and CrO42− because the majority of the retention capacity occurred at pH values between 6 and 10. A removal maximum was found for experiments with a 10:1 molar ratio and pH 8.0, achieving a 73.0 % removal of As(V) and a 94.0 % removal of Cr(VI). The evaluation of the effect of the contact time of the polymer–SR (species to remove) solution prior to diafiltration revealed that the interaction between TMC and the anions is produced rapidly. Furthermore, TMC selectivity in the presence of interfering ions, such as chloride and sulphate, and maximum retention capacity were evaluated. Finally, permeate flux behaviour was briefly discussed under different conditions of removal.

Liquid-Phase Polymer-Based Retention: Theory, Modeling, and Application for the Removal of Pollutant Inorganic Ions

The aim of this work is to give the theoretical background of liquid-phase polymer-based retention (LPR) technique, provide a complete model of separation process, and evaluate its application for the removal of pollutant inorganic ions (PIIs) from aqueous solution. Thus, fundaments of LPR modeling by washing method from the ion distribution in active and passive zones are specified and its application was evaluated for cadmium removal using poly(sodium styrene sulfonate) as water-soluble polymer (WSP). LPR simulations were performed using a semiempirical description from data of concentration, filtration factorm, and retention coefficients. It is concluded that semiempirical simulation of PII retention by WSP can be performed from a small amount of experimental data using the described modeling. In addition, new approximations associated with molecular structure of polymer should be performed and linked to parameters of LPR experiments.

Water-soluble polyelectrolyte in conjunction with membrane systems: modeling and simulation of retention profiles from washing method

Liquid-phase polymer-based retention (LPR) is a novel technique for eliminating, concentrating and separating pollutants from aqueous effluents. Using the washing method, LPR can provide a retention profile that contains the contributions of all the factors associated with the retention. To advance the LPR technique and further our understanding of polymeric systems in aqueous solutions, a model of the retention profile was developed and applied to Cu2+ retention. The removal of Cu2+ was studied with LPR experiments employing various polymers, a range of pH values (2.0, 3.5, and 5.0) and different interfering species (Co2+, Ni2+, and Zn2+). The resulting retention profiles were simulated from the experimental data. The results revealed constant R syst values at pH 5.0. However, at pH 3.5 and 2.0, R syst by PVPA exhibited the following behavior: Cu2+ > Zn2+ > Co2+ > Ni2+ and Cu2+ > Co2+ ≈ Ni2+ > Zn2+, respectively. In addition, our results suggested that at pH 6.0, Co2+, Zn2+ and Ni2+ affected the Cu2+ retention by PVPA by decreasing the retention capacity due to the competition of ions for functional groups on the polymer chains, whereas at pH 2.0, the preferential retention of Cu2+ and Ni2+ was observed.

Water‐soluble polymer and photocatalysis for arsenic removal

ABSTRACTIn this study, the photocatalytic oxidation of hazardous arsenite (As(III)) to arsenate (As(V)) and the sequential removal of arsenate from aqueous solution by liquid‐phase polymer‐based retention (LPR) were investigated. The photocatalytic oxidation of arsenite was performed using TiO2 (P25 Degussa, Germany) under UV‐A light. The optimal photocatalytic conditions to oxidize 10 mg L−1 of arsenite solution were achieved using a 0.5 g L−1 of catalyst at a pH value of 2. The As(III) oxidation reached 100% after 30 min of illumination with UV‐A light. A water‐soluble polymer containing quaternary ammonium groups, poly(3‐acrylamidopropyl)trimethylammonium chloride (P(ClAPTA)), was used as an extracting reagent in the LPR process. To obtain the optimized conditions, the removal experiments were performed at various polymer : As(V) molar ratios using 10 mg L−1 of arsenate solutions. After the oxidation of As(III) to As(V), the removal of arsenate by P(ClAPTA) was obtained in a 99% yield using a 20 : 1 polymer : As(V) molar ratio at a pH value of 9. The results demonstrate that the combination of these methods is highly useful for potential applications related to the treatment of wastewater contaminated with As(III). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40871.

Microwave assisted synthesis of Jeffamine cored PAMAM dendrimers

This study reports the use of a new microwave assisted amidation method for the synthesis of Jeffamine cored poly (amidoamine) (PAMAM) dendrimers up to fourth generations. Reaction proceeding is monitored by attenuated total reflectance (ATR) without final purification. It was found that current method decreases the aminolysis time, and minimizes the excessive use of reagents and solvents. Synthesized dendrimers were purified by liquid-phase polymer-based retention (LPR) technique and characterized by 1H-NMR, 13C-NMR, EA, GPC and UV–VIS spectroscopy.

WATER-SOLUBLE CATIONIC CELLULOSE COUPLED TO A ULTRAFILTRATION MEMBRANE FOR THE REMOVAL OF ARSENIC AND CHROMIUM

This article describes the retention properties of arsenic (V) and chromium (VI) using a water-soluble polymer based on cationic hydroxyethylcellulose and combined with an ultrafiltration membrane. The polymer was purchased commercially and was characterized by Fourier transform infrared spectroscopy (FTIR). The study of polymer removal capacity of As(V) and Cr(VI) were performed by liquid-phase polymer-based retention technique (LPR). By means of a washing method studied retention as a function of pH, the amount of polymer, and the concentration of As(V) and Cr(VI). The results showed that the retention capacity of both oxy-anions increases with the solution pH. Due to the presence of quaternary ammonium groups in the polymer structure, the retention of As(V) and Cr(VI) was higher at a pH of 9 than that at acidic pH levels, reaching values of 65% for Cr(VI) and 43% for As(V). The study in function of amount of polymer showed that using 75 mg the retention of As(V) was 65%. In the case of Cr(VI) using 50 mg of polymer, 67% retention was obtained. Using low concentrations for arsenic and chromium, maximum retention was found at 65% and 95%, respectively. The maximum retention capacity (MRC) of the polymer was determined by adding As(V) and Cr(VI) to the polymer solution and concentrating in successive steps. FTIR spectra before and after of retention showed differences by the interaction with oxy-anions.

Removal of As(V) using liquid-phase polymer-based retention (LPR) technique with regenerated cellulose membrane as a filter

In this study, regenerated cellulose membrane was used as a filter in liquid-phase polymer-based retention technique. The poly(4-vinyl-1-methylpyridinium bromide), P(BrVMP), was used as extracting reagent of As(V). The role of pH, polymer:As(V) molar ratio, and influence of regenerated cellulose membrane were investigated by washing method. It was observed that the efficient retention was obtained at pH 9 with 20:1 polymer:As molar ratio and it was about 100 % at Z = 10 for P(BrVMP). Experimental data showed that the regenerated cellulose membrane, compared to poly(ethersulfone) membrane, has a capacity to interact with As(V). The maximum retention capacity of P(BrVMP) was determined by enrichment method, and then, using alternately washing and enrichment methods, the charge–discharge process and recovery of P(BrVMP) were performed.

Boron removal by liquid‐phase polymer‐based retention technique using poly(glycidyl methacrylate N‐methyl D‐glucamine)

AbstractThe removal of boron was analyzed by liquid‐phase polymer based retention (LPR) technique using washing and enrichment method. The extracting reagents were water‐soluble polymers (WSPs) containing quaternary ammonium salts and N‐methyl‐D‐glucamine (NMG) groups. The removal experiments of boron using the washing method were conducted at 1 bar of pressure by varying pH, polymer:boron molar ratio, and concentrations of interfering ions (chloride and sulfate). The results showed higher retention capacity for boron (60%) at pH 10 with the polymer containing NMG group. The optimal polymer:boron molar ratio was 40 : 1. Selectivity experiments showed that the presence of interfering ions did not affect the boron removal capacity. The maximal boron retention capacity was determined by the enrichment method, obtaining a value of 12 mg B/g‐polymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Novel N-methyl-D-glucamine-based water-soluble polymer and its potential application in the removal of arsenic

A new water-soluble polymer based on the N-methyl-D-glucamine (NMG) group was prepared and characterized, and its arsenic retention capacity was studied using the liquid-phase polymer-based retention (LPR) technique.The monomer glycidyl methacrylate-N-methyl-D-glucamine (GMA–NMG) was synthesized, and the polymer was subsequently obtained through radical polymerization using ammonium persulfate as an initiator reagent. The polymer was dissolved in water, purified and fractionated with ultrafiltration membranes with molecular weight cut-offs of 50,000Da. The polymer was then characterized by potentiometric titration, FTIR and 1H NMR spectroscopy.The removal of arsenic was analyzed using the LPR technique with both the washing and enrichment methods. The removal experiments using the washing method were conducted by varying the pH, polymer:As(V) molar ratio, and concentrations of interfering ions. P(GMA–NMG) showed a high affinity for binding arsenate species (82% of removal) at pH 3.0. The optimum molar ratio was 70:1 polymer:As(V). Selectivity experiments showed that the presence of interferents gradually decreased the arsenic removal capacity. The maximum retention capacity was determined by the method of enrichment, obtaining a value of 45.9mgAsg−1 polymer.Finally, the results showed that the combination of P(GMA–NMG) with ultrafiltration membranes is a potential alternative for the removal of hazardous As(V) species from aqueous solutions at acidic pH.

Liquid‐Phase Polymer‐Based Retention of Chromate and Arsenate Oxy‐Anions

AbstractThe retention of chromate and arsenate anions was studied by liquid‐phase polymer based retention (LPR) technique by washing and enrichment methods. The extracting agents were water‐soluble cationic polymers (WSCPs) containing quaternary ammonium salts with chloride or methylsufate counterions. Through to washing method, the Cr(VI) and As(V) removal experiments were carried out at different pH (3, 6, 9) using WSCPs. The results showed highest retention capacity of Cr(VI) and As(V) at pH 9. The retention capacity in both cases was optimum for polymers containing chloride counterions. The decrease in the arsenic retention ability of the WSCPs is likely due to an increase in the ionic strength of solution by the presence of different concentrations of Na2SO4 or NaCl. The study of polymer:anion ratio showed the optimum molar ratio as 10:1 and 20:1 for efficient chromium and arsenic removal respectively. The maximum retention capacity (MRC) was determined by the enrichment method. It was between 79 to 165 mg ion retained/g polymer.The FT‐IR spectra of polymer‐anion were compared after and before to the maximum retention capacity showing differences due to the presence of Cr(VI) ions.The retention‐elution process shows that the elution process of the arsenate ions from polymers can be performed when the polymer‐arsenate was in contact with the acid solution from the reservoir.

Removal of arsenate from ionic mixture by anion exchanger water-soluble polymers combined with ultrafiltration membranes

This study shows the influence of Cl−, SO4 2−, NO3 −, SiO3 2−, Na+, and Ca2+ on arsenate removal by anion exchanger polymers using the liquid-phase polymer-based retention (LPR) technique. The LPR was carried out in the presence of anion exchanger soluble polymers containing quaternary ammonium salts. These polymers were characterized by NMR. Compared with As(V) removal from deionized water, the results showed that in the presence of ionic mixture, the As(V) removal capacity decreased. However, P(ClVBTA) showed As(V) removal ability of 91 % when the ionic mixture was used. Polymers with chloride exchanger groups showed a higher ability to remove arsenate than the polymer that contains methyl sulfate as anion exchanger group. At higher arsenate concentration (47.6 mg L−1), arsenate retention by the water-soluble polymers ranged between 58 and 91 %. This removal capacity increased gradually reaching 100 % retention when the arsenate concentration in the cell was minimum (5.5 mg L−1). The values of maximum retention capacity were 264 mg g−1 for P(ClMPTA), 260 mg g−1 for P(ClVBTA), and 200 mg g−1 for P(ClAPTA) at the total filtrate volume of 300 mL. The charge–discharge process found to be suitable for saturate the polymer with As(V) and then eluting As(V) for regenerating the extracting capacity of polymer.