Polymeric Sorbent Research Articles

Using neutron powder diffraction and first-principles calculations to understand the working mechanisms of porous coordination polymer sorbents.

Metal-organic frameworks (MOFs) are promising solid sorbents, showing gas selectivity and uptake capacities relevant to many important applications, notably in the energy sector. To improve and tailor the sorption properties of these materials for such applications, it is necessary to gain an understanding of their working mechanisms at the atomic and molecular scale. Specifically, it is important to understand how features such as framework porosity, topology, chemical functionality and flexibility underpin sorbent behaviour and performance. Such information is obtained through interrogation of structure-function relationships, with neutron powder diffraction (NPD) being a particularly powerful characterization tool. The combination of NPD with first-principles density functional theory (DFT) calculations enables a deep understanding of the sorption mechanisms, and the resulting insights can direct the future development of MOF sorbents. In this paper, experimental approaches and investigations of two example MOFs are summarized, which demonstrate the type of information and the understanding into their functional mechanisms that can be gained. Such information is critical to the strategic design of new materials with targeted gas-sorption properties.

Graphene oxide reinforced polymeric ionic liquid monolith solid-phase microextraction sorbent for high-performance liquid chromatography analysis of phenolic compounds in aqueous environmental samples.

A graphene oxide reinforced polymeric ionic liquids monolith was obtained by copolymerization of graphene oxide doped 1-(3-aminopropyl)-3-(4-vinylbenzyl)imidazolium 4-styrenesulfonate monomer and 1,6-di-(3-vinylimidazolium) hexane bihexafluorophosphate cross-linking agent. Coupled to high-performance liquid chromatography, the monolith was used as a solid-phase microextraction sorbent to analyze several phenolic compounds in aqueous samples. Under the optimized extraction and desorption conditions, linear ranges were 5-400 μg/L for 3-nitrophenol, 2-nitrophenol, and 2,5-dichlorophenol and 2-400 μg/L for 4-chlorophenol, 2-methylphenol, and 2,4,6-trichlorophenol (R(2) = 0.9973-0.9988). The limits of detection were 0.5 μg/L for 3-nitrophenol and 2-nitrophenol and 0.2 μg/L for the rest of the analytes. The proposed method was used to determine target analytes in groundwater from an industrial park and river water. None of the analytes was detected. Relative recoveries were in the range of 75.5-113%.

Determination of antimony and bismuth in technogenic raw materials

The paper describes determination of antimony and bismuth in the metal-containing technogenic raw materials by atomic absorption spectrometry with electrothermal atomization (AAS with ETA). To improve the metrological characteristics, we used modification of the graphite furnace by complex compounds of precious metals and in some cases separation and concentration of antimony and bismuth by N,S-containing heterochain polymeric sorbents.

Synthesis and characterization of a novel acryl amide-based yttrium imprinted sorbent via the ATRP approach for the preparation of medical-grade 90Y

Abstract Because of its favorable radionuclidic properties (pure beta emitter, E βmax = 2.28 MeV, T 1/2 = 64.1 h), the preparation of carrier free 90Y is of a great importance in radiopharmacy. Herein, we report the synthesis, characterization, and application of a novel yttrium sorbent prepared on the basis of the ion-imprinting concept. The ion-imprinted polymer (IIP) was prepared by atom transfer radical copolymerization of acryl amide (AAm, functional monomer) and N,N′-methylenebisacrylamide (MBAAm) crosslinking agent in the presence of a complex of yttrium ions (template ions) with a homemade chelator, i.e., 2,2-bis(2-bromo-2-methylpropanoate)propane-1,3-disuccinate (also as initiator). For elimination of yttrium ions, which act as the template, the prepared particles were treated with 50% v:v HCl : H2O to produce yttrium-imprinted polymeric sorbent. To control the imprinting effect, corresponding non-imprinted particles (NIP) were prepared in a similar manner except that yttrium ions were not used. The synthesized chemicals for the preparation of the chelator-initiator compound and the product itself were assessed in every step using 1H-NMR analysis. NIP and YIP were subjected to X-ray diffraction (XRD), infra-red spectroscopy (IR) and BET surface area analysis for characterization studies. Sorption/desorption studies were conducted, and the effects of potentially interfering ions, such as Sr2+ (α = 119.69) and Zr4+ (α = 73.01) in presence of radio-yttrium, were investigated (particle size: 50–100 μm, resultant recovery of > 99% within 60 min and a capacity of 33.33 mg Y(III) per gram of sorbent). The results showed that amounts of radio-yttrium as low as 250 μg could be extracted effectively with high radionuclidic and radiochemical purity from macro-gram amounts of strontium.

Synthesis and application of ion-imprinted polymer for extraction and pre-concentration of iron ions in environmental water and food samples

In this work, a novel Fe(III) ion imprinted polymer as a sorbent for extraction of iron ions from different samples was synthesized. Precipitation of thermal copolymerization was used for preparation of polymeric sorbent. In this technique, methacrylic acid, ethylene glycoldimethacrylate, 2,2′-azobisisobutyronitrile and (DHBPT)2 {(DHBPT)2=3,6-bis (3,5-dimethyl-1-H-pyrzol-1-yl)-1,2-dihydro-1,2,4,5-tetrazine)} were used as monomer, cross-linker, initiator and ligand, respectively, in the presence of Fe(III) ions and ethanol as a porogenic solvent. Moreover, control polymer (NIP) particles were similarly prepared without the Fe(III) ions. XRD, FT-IR, SEM and nitrogen adsorption–desorption techniques have been used to characterization of these prepared polymeric samples. Iron ion imprinted polymer particles, abbreviated as Fe(III)–IIP, were leached with 50mL of HCl (50% (v/v)). Absorption capacity for ion imprinted polymer was calculated about 40.41mg·g−1. Per-concentration of iron ion was investigated as a function of pH, weight of IIP, adsorption and desorption times, and volumes of sample. FAAS technique was used to determination of Fe(III) ion in the foods and waters samples.

Synthesis and properties of polymeric and organo-inorganic amphiphilic sorbents molecularly imprinted with cholesterol

Polymeric and organo-inorganic sorbents molecularly imprinted with cholesterol were synthesized to create selective hemosorbents for efferent therapy of hypercholesterlemia. These sorbents are block copolymers of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate and granulated organo-inorganic sorbents in which the imprinting was performed in the layer of the above copolymer on the surface of selenium (Se) nanoparticles stabilized with polyvinyl pyrrolidone. The physicochemical and sorption properties of the sorbents were studied.

Determination of Antioxidant Composition in Berry Juices Using Solid Phase Extraction with Copper Phthalocyanine

The paper studies selective extraction of organic fractions with antioxidant activity from plant raw materials on the new sorbent with surface layer of phthalocyanine metal complexes and further HPLC determination. The possibility of sorption concentration of the antioxidant substances amount, which include mostly vitamin B groups, on the layer of copper phthalocyanine on polymer sorbent Polysorb-2. We determined antioxidant composition of honeysuckle, huckleberry and cowberry juice, namely, gallus, gentisinic, chlorogenic, caffeic, cumaric and p-methoxybenzoic acids; epicatechin and quercetine. Detection limit of this technique is 5 mg/l using copper phthalocyanine in the concentrator.

Novel polymeric sorbents based on imprinted Hg(II)-diphenylcarbazone complexes for mercury removal from drinking water

Hg(II)-imprinted polymers were analyzed by Fourier transform infrared spectroscopy. The spectrum of IIP2, prepared using diphenylcarbazone, showed two additional peaks attributed to the stretching of nitrogen bonded to the aromatic carbon of diphenylcarbazone, not found in IIP1. Comparing leached and unleached IIP2, the peak shape of C=N (1636.3 cm−1) in unleached IIP2 was drastically changed emphasizing the interaction of mercury with nitrogen on 4VP. Moreover, a slight shift of the additional peaks was observed. These results show the possible interaction of mercury ions both with the nitrogen bonded to the aromatic carbon of diphenylcarbazone and the nitrogen of the monomer.

Oil Sorbent from Polyethylene-Terephthalate Wastes

Composites of polymer sorbents from waste polyethylene terephthalate, thermally expanded graphite (TEG), oxidized graphite (OG), and blowing agent are developed. Their physicomechanical properties (friability, grindability, density, porosity, specific surface area), surface structure, adsorption properties, and toxicity are investigated.

Preconcentration of indapamide from human urine using molecularly imprinted solid-phase extraction.

A simple, sensitive, and selective molecularly imprinted solid-phase extraction and spectrophotometric method has been developed for the clean-up and preconcentration of indapamide from human urine. Molecularly imprinted polymers were prepared by a non-covalent imprinting approach using indapamide as a template molecule, 2-(trifluoromethyl) acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, N,N-azobisisobutyronitrile as a thermal initiator and acetonitrile as a porogenic solvent. A non-imprinted polymer was also prepared in the same way, but in the absence of template. Molecularly imprinted polymer and non-imprinted polymer sorbents were dry-packed into solid-phase extraction cartridges. Eluates from cartridges were analyzed using a spectrophotometer for the determination of indapamide by referring to the calibration curve in the range 0.14-1.50 μg/mL. Preconcentration factor, limit of detection, and limit of quantification were 16.30, 0.025 μg/mL, and 0.075 μg/mL, respectively. A relatively high imprinting factor (9.3) was also achieved and recovery values for the indapamide spiked into human urine were in the range of 80.1-81.2%. In addition, relatively low within-day (0.17-0.42%) and between-day (1.1-1.4%) precision values were obtained as well. The proposed molecularly imprinted solid-phase extraction and spectrophotometric method was successfully applied to selective extraction, preconcentration, and determination of indapamide from human urine samples.

Highly selective nanocomposite sorbents for the specific recognition of S-ibuprofen from structurally related compounds

The aim of the present work was to synthesize highly homogeneous synthetic recognition units for the selective and specific separation of S-ibuprofen from its closely related structural analogues using molecular imprinting technology. The molecular imprinted polymer wrapped on functionalized multiwalled carbon nanotubes (MWCNT-MIP) was synthesized using S-ibuprofen as the template in the imprinting process. The characterization of the products and intermediates were done by FT-IR spectroscopy, PXRD, TGA, SEM and TEM techniques. The high regression coefficient value for Langmuir adsorption isotherm (R 2 = 0.999) showed the homogeneous imprint sites and surface adsorption nature of the prepared polymer sorbent. The nano-MIP followed a second-order kinetics (R 2 = 0.999) with a rapid adsorption rate which also suggested the formation of recognition sites on the surface of MWCNT-MIP. MWCNT-MIP showed 83.6 % higher rebinding capacity than its non-imprinted counterpart. The higher relative selectivity coefficient (k′) of the imprinted sorbent towards S-ibuprofen than that for its structural analogues evidenced the capability of the nano-MIP to selectively and specifically rebind the template rather than its analogues.

Multi-residue determination of 10 selected new psychoactive substances in wastewater samples by liquid chromatography–tandem mass spectrometry

New psychoactive substances (NPSs) have become increasingly popular in recent years. The analysis of these substances in influent wastewater (IWW) can be used to track their use in communities. In addition, an evaluation of the amount of NPSs released to the aquatic environment can be performed through the analysis of effluent wastewater (EWW). This study presents the development, validation and application of an analytical methodology, based on solid phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), for the determination of 10 NPSs in IWW and EWW. Synthetic cannabinoids, cathinones, piperazines and pyrrolidophenones are included among the target analytes. To the authors’ knowledge, it is the first time that eight out of these substances (4’-methylpyrrolidinobutyrophenone (MPPP), a-pyrrolidinopentiophenone (a-PVP), 2-[(1S,3R)-3-hydroxycyclohexyl]-5-(2-methyl-2-octanyl) phenol (CP47,497), (1-naphthyl(1-pentyl-1H-indol-3-yl) methanone (JWH-018), (1-butyl-1H-indol-3-yl)(1-naphthyl) methanone (JWH-073), (4-ethyl-1-naphthyl)(1-pentyl-1H-indol-3-yl) methanone (JWH-210), (4-methyl-1-naphthyl) (1-pentyl-1H-indol-3-yl) methanone (JWH-122) and 2-(2-methoxyphenyl)-1-(1-pentyl-1H-indol-3-yl) ethanone (JWH-250)) are investigated in wastewater. The optimized conditions for the analysis of this set of compounds included a SPE clean-up step using a polymeric sorbent and the use of a pentafluorophenyl (PFP) chromatographic column. Despite the broad range of physicochemical properties of the analytes the method allowed acceptable absolute recoveries (40–109%) for all the studied compounds at different levels of concentration. Low method limits of detection (MLODs) were achieved, ranging between 0.3 and 10ng/L except for BZP and CP47,497 (20 and 23ng/L, respectively), allowing a reliable and accurate quantification of the analytes. The method was successfully applied to the analysis of IWW and EWW samples from five wastewater treatment plants (WWTPs) located in Santorini Island (a highly touristic resort in Greece). Four out of 10 compounds (a-PVP, CP47,497, JWH-122 and JWH-210) were detected at least in one sample, being the first evidence of their presence in wastewater. CP47,497 was the most ubiquitous and abundant compound, showing concentrations up to 634ng/L in some cases.

Sorption of americium(III) from multicomponent solutions with sorbents based on dibenzo-18-crown-6 and its derivatives

A sorption of metals from multicomponent nitric acid solutions that simulate process solutions resulting from reprocessing of spent nuclear fuel was studied. The sorbent used was a highly porous polymeric sorbent impregnated with crown ethers. Chemicals used in the work were dibenzo-18-crown-6 (DB18C6) and its alkyl-substituted derivatives: di-tert-butyldibenzo-18-crown-6 (DTBDB18C6) and diisooctyldibenzo-18-crown-6 (DIODB18C6). Sorption coefficients were determined for all elements. With the aim to study the possibility of isolation of 241Am from multicomponent solutions, separation factors for Am and ballast elements were determined. The possibility of application of sorbents impregnated with crown ethers for recovery of 241Am from multicomponent process solutions was shown.

Modification of industrial divinyl rubber by oxidative chlorophosphorylation and assess-ment of metal ion removal efficiency of obtained polymer sorbent

Abstract The main goal of this study was the preparation of materials containing phosphoric functionalities on the base of industrial polymer - divinyl rubber and the assessment of their removal efficiency of heavy metals from aqueous solutions. The new method concerns the oxidative chlo-rophosphorylation of divinyl rubber by PCl3 with the following modification of obtained inter-mediates to create -PO(OH)2, -OPO(OH)2 groups in the polymer chain. The obtained modified polymers get some new properties such as complex formation and capability for ion exchange. The nature and distribution of phosphoric functionalities in the polymer were studied by the methods of NMRand FTIR- spectroscopy, thermal analysis and scanning electron microscopy. The sorption properties of synthesized polymers towards some cations (Cu+2, Ni+2, Co+2 and Zn+2) from water solutions have been tested. It has been shown that the metal removal efficiency of prepared material depends on pH of medium, initial concentration and type of metal ions.

Determination of mitragynine in urine matrices by bar adsorptive microextraction and HPLC analysis

Bar adsorptive microextraction combined with liquid desorption followed by high performance liquid chromatography with diode array detection (BAµE-LD/HPLC-DAD) is proposed for the determination of the psychoactive alkaloid mitragynine (MG) in human urine matrices. By using a modified N-vinylpyrrolidone polymer (P2) sorbent phase, high selectivity and efficiency is achieved. Assays performed by BAµE(P2)-LD/HPLC-DAD on 25mL water samples spiked at the 8.0µgL−1 level yielded average recoveries around 100% of MG, under optimized experimental conditions. The analytical performance showed good precision (RSD<15%), appropriated detection limits of 0.10µgL−1 and linear dynamic ranges (0.6–24.0μgL−1) with convenient determination coefficients of 0.9924. By using the standard addition method, the application of the present methodology for the determination of MG in human urine matrices after Kratom consumer, allowed very good performances. The proposed methodology proved to be a suitable alternative to monitor MG in biological fluid matrices, showing to be easy to implement, reliable, sensitive and requiring low sample volumes, when compared with other sorbent-based methods.

Specifics of positron studies of microheterogeneous systems as applied to new polymeric sorbents

The size distribution of free volume holes in mesoporous, microheterogeneous polymer sorbents based on linear rubber-modified divinylbenzene copolymers has been studied. Analysis of the results of the study and published data has shown that positron annihilation lifetime spectroscopy (PALS) applied to microheterogeneous systems, in contrast to homogeneous systems, is not necessarily sensitive to mesopores that occur at the boundaries of heterogeneities and determine the sorption or membrane properties of the modified materials. To obtain the complete information, additional procedures such as low-temperature (BET) gas adsorption and thermally stimulated luminescence (TSL) need to be used. This circumstance is due to a considerably long distance between mesopores in heterogeneous systems and limited mobility of positronium during its localization in a pore. In addition to the BET data, which largely give information on mesopores, PALS appears useful for studying micropores. The TLS technique makes it possible to judge on heterogeneity of test materials. The minimal concentration of mesopores detectable by the positron technique in the systems of interest has been determined.

Synthesis and sorption properties of polymeric sorbents molecularly imprinted with uric acid

Polymeric sorbents molecularly imprinted with a uremic toxin, uric acid, were prepared by suspension copolymerization of 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate in the presence of uric acid. The physicochemical and sorption properties of the synthesized sorbents and of the corresponding control sorbents synthesized without uric acid were studied. The influence of the amount of the introduced template on the structural features and sorption capacity of the synthesized polymers was determined. As compared to control sorbents, the synthesized imprinted sorbents exhibit increased equilibrium sorption capacity for uric acid.

When some elementary free volumes in polymers are not seen by positron annihilation experiments

Size distributions of elementary free volumes have been studied in mesoporous micro-heterogeneous polymer sorbents. Positron annihilation lifetime spectroscopy (PALS), low temperature gas adsorption (BET) and thermo-stimulated luminescence (TSL) measurements are employed as complementary instruments for the study. It is shown that small admixtures of rubbers are very effective for variations of the pore size distribution. While BET technique was very informative for measurements of mesopores(2-50 nm), positron annihilation was sensitive to micropores(<2 nm), but not for mesopores. The last specificity is explained by the limited positronium diffusion length in a polymer and also by inhomogeneous distribution of mesoporesin heterogeneous systems. TSL measurements gave information on sizes of rubber inclusions in compositions.

Peculiarities of the transport properties of chitosan films. 1. Concentration prehistory of pervaporation

Chitosan films prepared by the thermal method from molding solutions containing ethanol as a chitosan precipitant have been used as separating membranes for pervaporation of an aqueous isopropanol solution. The flux density and permeate composition have been determined as functions of the composition of a molding solution and a solution to be separated, as well as the concentration prehistory of the separation process. The concentration prehistory reflects the specific features of swelling polymer sorbents, which are distinguished by a labile structure and macroscopic sorption deformations. The existence of a concentration prehistory implies that, at a fixed concentration of an initial solution, parameters characterizing the transport properties of a polymer depend on the process route in which this concentration has been achieved. The composition of a molding solution and the route of variations in the initial concentration of a solution to be separated that correspond to the highest value of our criterion for the process efficiency have been determined. It has been shown that, in the case of films formed from a solution containing 20 wt % ethanol, the water flux density reversibly increases by more than 100 times as compared with the flux density of a water-alcohol solution.

Automated direct-immersion solid-phase microextraction using crosslinked polymeric ionic liquid sorbent coatings for the determination of water pollutants by gas chromatography.

Four different crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were evaluated in an automated direct-immersion solid-phase microextraction method (automated DI-SPME) in combination with gas chromatography (GC). The crosslinked PIL coatings were based on vinyl-alkylimidazolium- (ViCnIm-) or vinylbenzyl-alkylimidazolium- (ViBzCnIm-) IL monomers, and di-(vinylimidazolium)dodecane ((ViIm)2C12-) or di-(vinylbenzylimidazolium)dodecane ((ViBzIm)2C12-) dicationic IL crosslinkers. In addition, a PIL-based hybrid coating containing multi-walled carbon nanotubes (MWCNTs) was also studied. The studied PIL coatings were covalently attached to derivatized nitinol wires and mounted onto the Supelco assembly to ensure automation when acting as SPME coatings. Their behavior was evaluated in the determination of a group of water pollutants, after proper optimization. A comparison was carried out with three common commercial SPME fibers. It was observed that those PILs containing a benzyl group in their structures, either in the IL monomer and crosslinker (PIL-1-1) or only in the crosslinker (PIL-0-1), were the most efficient sorbents for the selected analytes. The validation of the overall automated DI-SPME-GC-flame ionization detector (FID) method gave limits of detection down to 135 μg · L(-1) for p-cresol when using the PIL-1-1 and down to 270 μg · L(-1) when using the PIL-0-1; despite their coating thickness: ~2 and ~5 μm, respectively. Average relative recoveries with waters were of 85 ± 14 % and 87 ± 15 % for PIL-1-1 and PIL-0-1, respectively. Precision values as relative standard deviation were always lower than 4.9 and 7.6 % (spiked level between 10 and 750 μg · L(-1), as intra-day precision). Graphical Abstract Automated DI-SPME-GC-FID using crosslinked-PILs sorbent coatings for the determination of waterpollutants.