Polymeric Sorbent Research Articles

Facile fabrication of biobased porous material via the photocuring technique and a template-assisted approach for oil/water separation

In this study, we developed a facile, low-cost and eco-friendly approach to prepare a sustainable, porous, polymeric sorbent for oil/water separation by using photocurable soybean oil-based urethane methacrylate and inexpensive salt porogen as raw materials. By combining UV curing technology and a salt template-assisted method, a biobased porous sorbent with good hydrophobicity, lipophilicity, and recyclability was prepared. The effects of particle size and content of salt porogen on the density, morphology, porosity and surface wettability of porous sorbent were analyzed and discussed in detail to optimize the preparation conditions. Due to its unique three-dimensional porous structure and large specific surface area, the prepared biobased porous material exhibits the ability of rapid organic solvent absorption and could serve as sorbents that effectively realized the separation of oil/water mixtures. Moreover, all of the key materials are almost low cost and available in large quantities, meaning that this biobased porous material is expected to be used in oil/water separation on a large scale.

Efficient recovery of aromatic compounds from the wastewater of styrene monomer and propylene oxide co-production plant via hypercrosslinked aryl-rich starch-β-cyclodextrin polymeric sorbent

• A hydrophilic HSPS-ACD(H) with high porosity was fabricated. • HSPS-ACD(H) is a new benchmark sorbent for uptake of AP and 1-PE. • Competitive or synergetic adsorption of co-existing aromatics was studied. • Efficient recovery of the target aromatics was demonstrated in fixed bed column. • DFT calculations provided insights into mechanism for selective adsorption. Adsorptive recovery of valuable components from industrial wastewater is highly desirable for avoiding resource wastage but remains a challenge. Herein, we develop an efficient continuous adsorption process for recovering aromatic compounds in wastewater from styrene monomer and propylene oxide co-production (SMPO) plant. Based on our insight into the potential of bio-based porous materials for adsorption application, starch-graft-polystyrene (SPS) and aryl-modified β-cyclodextrin (ACD) were prepared, and novel hypercrosslinked porous polymers combined SPS with ACD (HSPS-ACDs) were synthesized through external crosslinking approach. In a binary-component system, the best-performing one HSPS-ACD(H) with high ACD content and large specific surface area possessed superior capacities for the representative aromatic compounds, acetophenone (AP, 2.81 mmol·g −1 ) and 1-phenylethanol (1-PE, 1.35 mmol·g −1 ) compared with the previously reported materials. Further, the adsorption properties of aromatic compounds on HSPS-ACD(H) were investigated in batch mode. For practical application, continuous adsorption experiments were conducted in a HSPS-ACD(H)-packed fixed bed, where the target aromatic components in wastewater were effectively retained and further released by elution. Besides showing the reversible adsorption and efficient enrichment effect, the HSPS-ACD(H)-packed fixed bed also maintained great stability in multiple cycles. Moreover, quantum chemical calculations were performed to elucidate the potential mechanism of adsorption of AP and 1-PE onto HSPS-ACD(H).

Novel chemically cross-linked self-molding particulate sorbents as solid-phase extraction media.

Here, we describe novel, chemically cross-linked, self-molding particulate polymer sorbents that are utilized as a molding-type solid-phase extraction medium (M-SPEM), which exhibits high permeability and rigidness. To fabricate such M-SPEM, first, polyethyleneimine (PEI)-modified reversed-phase (RP)-type particulate sorbents were synthesized, thereafter, they were chemically cross-linked by a polymer having many epoxy groups together with additional PEI. By optimizing the binding conditions of the particulate sorbents, the resultant M-SPEM has almost the same adsorption properties as the corresponding unmolded particulate sorbent for some polar (e.g., uracil and adenine) compounds. The binding technique proposed here is expected to facilitate the fabrication of molding-type sorbents and improve the performance of the SPE procedure.

Complementary biomarker detection for bisphosphonate use in racehorses

Determining the use of off-label bisphosphonates (BPs) in young horses (< 4 years old) is of interest due to the threat to racing integrity and welfare associated with this class of drugs that have the potential to manipulate bone structure. The analysis of BPs in biological matrices is challenging by liquid chromatography coupled to mass spectrometry (LC-MS/MS) and alternative sample preparation approaches are needed to detect their misuse in racehorses. There are currently two classes of BPs: non-nitrogen and nitrogen-containing with each having a distinct mode of action. Currently two non-nitrogenous based BPs are available for use in horses, tiludronic acid (or tiludronate) and chlodronate for the treatment of navicular syndrome (Mitchell et al. BMC Veterinary Research 2019;15(1):211) in horses over the age of 4. There is, however, evidence that BPs can persist in the bone for several years after administration since they can form hydroxyapatite crystals prior to being fully absorbed by active osteoclasts where full inhibitory action is performed (Riggs et al. Equine veterinary journal 2021;53(6):1287–1295). Therefore, with this prolonged detection time for the BPs, it is necessary to investigate whether the use of metabolomic biomarkers can provide a complementary method for the detection of their misuse. The aim of this research was to develop a biomarker approach for complementary direct detection of bisphosphonate drugs in equine plasma. BPs are hydrophilic therefore the targeted detection of tiludronic acid in equine plasma required an orthogonal solid phase extraction (SPE) method using both a polymeric reversed-phase sorbent and a weak anion exchange cartridge prior to derivatisation using trimethyl orthoacetate and reverse LC-MS/MS. Endogenous lipids and corticosteroids in equine plasma were detected after protein precipitation and SPE with a polymeric reverse phase cartridge prior to liquid chromatography high-resolution mass spectrometry. Data was analysed using the Shimadzu Insight Explore software to determine up- or down-regulation of biomarkers. Results were then profiled using a Parametric Empirical Bayes algorithm to propose individual reference limits (IRLs). Tiludronic acid was detected up to the final collection point of 28 days post-administration. Following a targeted approach, up- and down-regulation of the eicosanoid and corticosteroid ratios were observed with the corticosteroid ratio exceeding both the proposed population reference limit (PRL) and IRL. Using a semi-targeted approach, several additional lipids were identified to have activity during the administration and will require further confirmatory analysis. Monitoring the impact on endogenous biomarkers following an administration of Tiludronic Acid in racehorses is limited therefore little is known if BPs have a direct or indirect effect on the inflammatory pathways. However, research in humans has linked BPs with possible effects of analgesia in addition to bone remodelling that BPs are primarily used for. Therefore, it is necessary to further extend detection capabilities to ensure endogenous eicosanoids and corticosteroids are monitored. This, however, should not negate the need for the detection of the drug itself as tiludronic acid has the potential to be detected as far as 28 days post-administration. Therefore, a complementary biomarker approach would be preferable for the detection of non-nitrogen-based BPs, which can be further applied for the nitrogen-based BPs. A complementary biomarker approach to direct detection of administered drugs can improve the understanding of effect and support non-targeted detection strategies for analogues of specific drug classes.

Selective isolation of pesticides and cannabinoids using polymeric ionic liquid-based sorbent coatings in solid-phase microextraction coupled to high-performance liquid chromatography

The high abundance of cannabinoids within cannabis samples presents an issue for pesticide testing as cannabinoids are often co-extracted with pesticides using various sample preparation techniques. Cannabinoids may also chromatographically co-elute with moderate polarity pesticides and inhibit the ionization of pesticides when using mass spectrometry. To circumvent these issues, we have developed a new approach to isolate commonly regulated pesticides and cannabinoids from aqueous samples using tunable, crosslinked imidazolium polymeric ionic liquid (PIL)-based sorbent coatings for direct immersion solid-phase microextraction (DI-SPME). The selectivity of four PIL sorbent coatings towards 20 pesticides and six cannabinoids, including cannabidiol and Δ9-THC, was investigated and compared against a commercial PDMS/DVB fiber. Extraction and desorption conditions, including salt content, extraction temperature, pH, extraction time, desorption solvent, and desorption time, were optimized using high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. Under optimized conditions, the PIL fiber consisting of 1-vinylbenzyl-3-octylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([VBIMC8+][NTf2−]) and 1,12-di(3-vinylbenzylimidazolium)dodecane dibis[(trifluoromethyl)sulfonyl]imide ([(VBIM)2C122+]2[NTf2−]) sorbent coating provided the best selectivity towards pesticides compared to other PILs and the PDMS/DVB fibers and was able to reach limits of detection (LODs) as low as 1 µg/L. When compared to a previously reported PIL-based SPME HPLC-UV method for pesticide analysis, the amount of cannabinoids extracted from the sample was decreased 9-fold while a 4-fold enhancement in the extraction of pesticides was achieved. Additionally, the PIL-based SPME method was applied to samples containing environmentally-relevant concentrations of pesticides and cannabinoids to assess its feasibility for Cannabis quality control testing. Relative recoveries between 95% and 141% were obtained using the PIL sorbent coating while recoveries ranging from 50% to 114% were obtained using the PDMS/DVB fiber.

Adsorption of Hydrophobic Ions on Environmentally Relevant Sorbents.

Environmental monitoring and remediation often requires the collection of harmful substances from aqueous solutions. Absorption with solids is a useful technique for binding such substances even at very low concentration levels. Many of these contaminants are weak acids or bases. Some novel, nonionic polymeric sorbents, such as hypercrosslinked polymers or polymers with balanced hydrophilic-lipophilic properties (HLB) have been found to bind weak acids and bases with high distribution coefficients even at pH values where these compounds are almost completely ionized (typically near pH 7). To understand this phenomenon and its practical consequences, we have experimentally studied the adsorption of ionizable weak acids and bases as a function of pH and ionic strength on a the OASIS® HLB sorbent. Not surprisingly, the ionic forms of the weak acids and bases were found to be much less bound in the aqueous solution than their neutral forms. In spite of this, OASIS® HLB binds weak acids and bases around pH 7 considerably better than typical hydrophobic sorbents. The high overall distribution coefficients around pH 7 could be explained by two factors. One is that on OASIS® HLB, and on some other novel polymeric sorbents, the binding constant of the moderately hydrophobic neutral form is on the order of 100,000, i.e., much higher than on typical hydrophobic sorbents. Thus, even if the proportion of the neutral form in solution is only around 1% near pH 7, the adsorption of the neutral form is still significant. On the other hand, the binding of the apparently hydrophilic ionized forms occurs with distribution coefficients well above 100. The distribution coefficient of the ionic form appears to depend on ionic strength and the presence of competing ions. Adsorption of the ionic forms is found to be very similar to the adsorption of ionic surfactants. The pH dependence of the total adsorption of neutral and ionic forms together, is found to be steep around pH 7, and therefore the varying pH of natural waters may strongly influence the binding efficiency in practical applications, such as the collection (concentration) of contaminants or their passive sampling.

Design Considerations for Next‐Generation Polymer Sorbents: From Polymer Chemistry to Device Configurations

AbstractAdsorption‐based separations have the potential to enhance the sustainability of established industrial processes and facilitate the adoption of new practices. They also provide ways to meet emerging needs in the isolation of resources from non‐traditional supplies and the remediation of hazardous environmental contaminants. In this regard, there are significant opportunities to advance both fundamental polymer science and engineering applications through next‐generation adsorbent systems. Here, after briefly reviewing the history, potential application space, and underlying physics of polymer sorbents, design considerations that connect macromolecular design with systems‐level functionality, are discussed. First, polymer processing conditions are discussed in terms of the final nano‐ and microscale structures produced. Subsequently, the macromolecular chemistry of the materials is analyzed with respect to the ability of the separations systems to have analyte‐specific binding. Finally, a similar analysis is performed regarding the desorption mechanism used to release the target solutes. In this way, the manuscript attempts to connect macromolecular architecture with polymer physics and materials processing to provide guidance on how these important interrelationships impact the ultimate performance of sorbent systems.

Перспективы использования полимерсодержащих материалов и сорбентов для мембранной ультрафильтрации, сорбции и концентрирования нуклеиновых кислот из водных сред. Обзор

Unlike antibiotics and heavy metals, nucleic acids exist in the aquatic environment as a part of prokaryotic and eukaryotic microorganisms (bacteria, fungi, etc.) rather than in a free form. In this regard, the most important primary stage of sample preparation of an object for the quantitative analysis of DNA and RNA in natural and wastewaters includes membrane ultrafiltration of an aqueous sample, followed by its sorption preconcentration on a solid phase carrier. The efficiency of ultrafiltration and subsequent sorption of nucleic acids from natural and wastewaters largely depends on the material of filters, membranes, and sorbents. Polymeric materials are widely used due to their special properties: the affinity of polymers for biological objects, the ability to create pores of any required size, good mechanical properties and resistance to the extraction of microorganisms captured. The paper reviews the 15-year-old scientific literature on filtering, membrane and sorption polymeric materials used to extract nucleic acids from aqueous media and preserve them. Polymeric sorbents for collecting and concentrating DNA and RNA from the liquid phase, as well as storing nucleic acids, are covered. It has been found that ultrafiltration is used at a relatively low concentration of the analyzed object, followed by extraction of the substance using commercially available kits, including cartridges. Sorption (solid-phase concentration) is used to extract nucleic acids at their relatively high concentration in the analyte. The main polymeric materials used include cellulose and its derivatives (nitrocellulose, cellulose acetate, mixed cellulose nitrate–acetate, diethylaminoethylcellulose, polyethyleneiminocellulose), agarose, dextran, polyestersulfone, polycarbonate, fluoroplasts, polyacrylates and polymethacrylates, polyaramids, polyamides, polyvinyl alcohol, polyaniline, polycaprolactone, polyacrylamide and polymethacrylamide, polystyrene. Chitosan, modified polycaprolactone, and magnetic particles coated with polydopamine, polyethyleneimine, polyvinylpyrrolidone, polystyrene, or polyamidoamine dendrimer are considered as promising polymers for further research in this field.

Obtaining new polyfunctional ion-exchange sorbents

The purposeful synthesis of polymeric chelate-forming sorbents, distinguished by high efficiency, selectivity of action, cost-effectiveness, is one of the promising directions in the field of increasing selectivity of the sorption processes. The paper aims at the synthesis of new ionic compounds, based on the copolymers of glycidyl methacrylate and chelating agent - oxyethylidenediphosphonic acid. The preparation of the insoluble complex sorbents by the method of a chemical modification with the introduction of a soluble complexone, hydroxyethylidenediphosphonic acid, widely used in the industry and heat engineering, into the polymer matrix has been studied. The ways of obtaining new ion-exchange resins, based on a double copolymer of glycidyl methacrylate, methyl methacrylate and oxyethylenediphosphonic acid complexon, have been developed. The optimal mode for obtaining the ion exchangers, based on a double copolymer of glycidyl methacrylate, methyl methacrylate and oxyethylenediphosphonic acid, is the mass ratio of copolymer:acid 1.0:1.0, at a temperature of 90 0C, and heating during 10 hours. The yield of ion exchangers makes up 78-80%. The composition and structure of the obtained ionites have been identified by the infrared spectroscopy and elemental analysis. The static exchange capacity for 0.1 М NaOH solution is 5.92 mg-eq/g. It has been found that the obtained ionite has a satisfactory chemical resistance to various acids, alkalis and oxidants, the loss of the static exchange capacity does not exceed 7%. The resulting ionite can be used as a sorption material for the industrial wastewater treatment from various metal ions.

Water Sorption by Polyheteroarylenes.

The sorption–diffusion characteristics of rigid-chain glassy polymers based on polyheteroarylenes (PHAs) have been studied in a wide interval of relative humidity and temperatures of thermal treatment of the polymer sorbents. Experimental data on water vapor sorption for polynaphthoyleneimidobenzimidazole (PNIB) and its copolymers with different chemical nature have been obtained. Water diffusion coefficients have been calculated, and parameters of their concentration and temperature dependences have been determined. It was found that water molecules sorbed by PNIB and its copolymers are strongly bounded. Water mobile and cluster states depend on the structure of macromolecules and thermal prehistory of polymer sorbents. It is shown that the translational coefficients of water diffusion for all PHAs are in the range from 10−9 to 10−8 cm2/s. The diffusion coefficients also increase slightly with temperature increasing, and their general dependence on temperature is satisfactorily described by the Arrhenius equation. The average activation energy of water diffusion varies from 24.3 to 25.9 kJ/mol. The hydrate numbers of rigid-chain PHAs functional groups have been determined. The above-mentioned results allow us to predict the sorption properties of heterocyclic macromolecular sorbents with complex chain architecture.

THE STUDY OF HEAVY METAL ION SORPTION KINETICS

Phosphorus-containing polymeric sorbent based on butadiene-styrene rubber was used to remove zinc, iron and chromium ions from water. The research was carried out to study the sorption characteristics by determining the effects of various parameters, such as the pH of the solution, the initial concentration of metal ions, the sorbent mass, the phase contact time, and temperature. The regularities of the kinetics of the sorption of zinc, iron and chromium ions on the phosphorus-containing sorbent synthesized on the basis of butadiene-styrene rubber were studied. On the basis of the results it was defined that the process of sorption of zinc, iron and chromium ions on the cation exchanger proceeds by an ion-exchange mechanism. The kinetics of this process is a combination of external and internal diffusion kinetics (with some predominance of external diffusion kinetics) and is better described by the pseudo-second order reaction model. In addition, a certain contribution to the overall speed of the process is made by the interaction of the sorbed ions with the functional groups of the cation exchanger. Keywords: phosphorus-containing cation exchanger, zinc, iron, chromium, sorption, kinetics.

Methacrylate-Based Polymeric Sorbents for Recovery of Metals from Aqueous Solutions

The industrialization and urbanization expansion have increased the demand for precious and rare earth elements (REEs). In addition, environmental concerns regarding the toxic effects of heavy metals on living organisms imposed an urgent need for efficient methods for their removal from wastewaters and aqueous solutions. The most efficient technique for metal ions removal from wastewaters is adsorption due to its reversibility and high efficiency. Numerous adsorbents were mentioned as possible metal ions adsorbents in the literature. Chelating polymer ligands (CPLs) with adaptable surface chemistry, high affinity towards targeted metal ions, high capacity, fast kinetics, chemically stable, and reusable are especially attractive. This review is focused on methacrylate-based magnetic and non-magnetic porous sorbents. Special attention was devoted to amino-modified glycidyl methacrylate (GMA) copolymers. Main adsorption parameters, kinetic models, adsorption isotherms, thermodynamics of the adsorption process, as well as regeneration of the polymeric sorbents were discussed.

Renewable sorbent dispersive solid phase extraction automated by Lab-In-Syringe using magnetite-functionalized hydrophilic-lipophilic balanced sorbent coupled online to HPLC for determination of surface water contaminants

An automated methodology for magnetic dispersive solid phase microextraction integrating bead injection approach for renewable sorbent introduction is presented for the first time and was successfully applied to the enrichment of water contaminants. For this purpose, a simple procedure was developed for the functionalization of commercial SupelTM-Select HLB (Hydrophilic modified styrene polymer) sorbent beads that allowed embedding magnetite nanoparticles (Fe3O4). The sorbent was then used in a dispersive solid phase extraction procedure that was carried out entirely inside the void of an automatic syringe pump following the flow-batch concept of Lab-In-Syringe including automated renewal of the sorbent for each analysis. Mixing processes, sorbent dispersion, and sorbent recovery were enabled by using a strong magnetic stirring bar, fabricated from a 3D printed polypropylene casing and neodymium magnets, inside the syringe. The final extract was submitted to online coupled liquid chromatography with spectrometric detection. System and methodology were applied to determine mebendazole, bisphenol A, benzyl 4-hydroxybenzoate, diclofenac, and triclosan selected as models from different groups of environmental contaminants of current concern. Experimental parameters including extraction and elution times, composition and volume of eluent, and bead recollection were optimized. Required system elements were produced by 3D printing. Enlarging the sample volume by repeated extraction to enhance the sensitivity of the method was studied. Using double extraction from 3.5 mL, limits of detection ranged from 1.2 μg L−1 to 6.5 μg L−1 with an RSD (n = 6) value less than 7% for all the analytes at 25 μg L−1 level. The method was linear in the range of 5–200 μg L−1 and was successfully implemented for the analysis of surface waters with analyte recoveries ranging from 78.4% to 105.6%.

Sorption of silver (I) ions from aqueous solutions using the synthetic sorbent

We study the sorption of silver ions from aqueous solutions by a synthetic chelating sorbent. In the presence of formaldehyde, a polymeric sorbent based on a copolymer of styrene with maleic anhydride, modified with N,N’-diphenylguanidine, was synthesized and further used for extracting Ag(I) ions. The composition and structure of the synthesized polymeric chelating sorbent were studied using IR and UV spectroscopy methods. A simple, inexpensive, and efficient method for extracting Ag(I) ions from aqueous solutions was used. The effect of various parameters on the sorption process was studied, including the acidity of the medium (pH), the initial concentration of the metal ion, the time required to establish complete sorption equilibrium, and ionic strength. The optimum pH value for the extraction of Ag(I) was found to be 6. The process is characterized by a high adsorption capacity reaching 547.2 mg/g. The research results showed that the time required to establish a complete sorption equilibrium for the sorbent modified with N,N’- diphenylguanidine is 60 min. Ag(I) adsorption increases up to the value of ionic strength of μ = 1, after which its intensity decreases. At the final stage, the process of desorption of absorbed silver ions was carried out. During desorption, the best eluting agent for the extraction of Ag(I) was determined to be 0.5 M HNO3. The sorbent can be re-used after regeneration. The copolymer of styrene and maleic anhydride modified with N,N’-diphenylguanidine has a high sorption capacity and, therefore, can be used as a potential adsorbent for the extraction of silver (I) from aqueous solutions.

Central Composite Design (CCD) and Box-Behnken Design (BBD) for the Optimization of a Molecularly Imprinted Polymer (MIP) Based Pipette Tip Micro-Solid Phase Extraction (SPE) for the Spectrophotometric Determination of Chlorpyrifos in Food and Juice

A novel micro-solid phase extraction protocol based on a new molecularly imprinted polymer (MIP) sorbent is reported for the isolation of chlorpyrifos from rice, juice and fish samples followed by spectrophotometric determination. The MIP sorbent was packed into a pipette tip. The type and volume of the eluent, pH, mass of MIP, sample volume, and number of extraction and elution cycles were evaluated utilizing a one-variable-at-a-time protocol, central composite design, and Box-Behnken design. The results demonstrated the optimum performance of central composite design. The linear range under the optimal conditions for chlorpyrifos was from 1 to 1000 µg L−1 with a limit of detection of 0.17 µg L−1 and a relative standard deviation less than 4.3%. The protocol was successfully employed for the determination of trace concentrations of chlorpyrifos in fish, juice, and rice.

Synthesis and characterization of new polymer sorbents based on EGDMA and methacrylated cellulose

Synthesis and characterization of new polymer sorbents based on EGDMA and methacrylated cellulose

Functionalized microspheres with co-participated lignin hybrids as a novel sorbents for toxic C.I. Basic Yellow 2 and C.I. Basic Blue 3 dyes removal from textile sewage

The paper presents the synthesis of novel adsorbents in spherical form based on divinylbenzene, ethylene glycol dimethylacrylate and triethoxyvinylsilane, and lignin or its modified form with ZrO2 and SiO2, as hybrid materials of well-defined microstructural factors. In the first stage of the experiment, lignin was mechanochemically combined with the inorganic oxides in form of zirconia and silica. Then, the obtained material was used as a modifier in the preparation of the functionalized polymeric microspheres using the suspension polymerization method. To confirm the chemical structure of the lignin-based hybrid modifiers and the polymeric sorbents, ATR-FTIR and XPS spectroscopy as well as SEM analysis were performed. In addition, the parameters of the porous structure were determined. It was shown that mainly physical interactions occur between the inorganic and organic components, resulting in the formation of class I hybrid systems. Subsequently, the functionalized polymeric microspheres were used as effective sorbents of hazardous C.I. Basic Yellow 2 (BY2) and C.I. Basic Blue 3 (BB3) days from textile wastewaters. Equilibrium data for the sorption of BY2 and BB3 by the newly designed adsorbents show that Freundlich isotherm model describes the experimental data more appropriate than the Langmuir or Dubinin–Radushkevich ones. The Freundlich constant related to adsorption capability, kF, enlarged with rising amount of lignin, zirconia and silica, from 42.3 to 83.5 mg1–1/n L1/n/g for BB3 and from 11.1 to 45.7 mg1–1/n L1/n/g for BY2. Kinetic studies revealed favorable uptake of 50 mg/L BB3 during the first 60 min of phase contact time, compared with BY2. Anionic and non-ionic surfactants (0.25 g/L) and NaCl (25 g/L) slightly decreased dyes (50 mg/L) sorption from dyeing baths, and their retention was significantly reduced when a cationic surfactant was present in the bath. Desorption of BB3 and BY2 dyes from the hybrids, with yield in the ranges 20.8–32.0% and 24.8–99.0% respectively, was achieved applying 1 M HCl in the presence of 50% v/v methanol.

Development of organic-diffusive gradients in thin films technique for measuring freely dissolved concentrations of tetracyclines using a commercial SPE packing

The freely dissolved concentrations (FDCs) of pollutants are related to their bioavailability in the environment, and the diffusive gradients in thin films technique (DGT) can obtain the FDC of an analyte. Aiming for the detection of the FDCs of tetracyclines (TCs), we used a polyacrylamide hydrogel comprising acrylamide and acrylaide agarose cross-linker as diffusive and binding gels, and a commercial solid-phase extraction (SPE) packing, namely polymer sorbent (PLS), as an adsorption material in the binding gel for the preparation of the organic-diffusive gradients in thin films (o-DGT) devices. The results showed that the diffusion coefficients of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) in the diffusive gels were 1.08 × 10−6, 1.08 × 10−6 and 1.03 × 10−6 cm2/ s at 25 °C, respectively. The binding gel showed excellent performance with adsorption capacities of 534.88–569.42 µg/disc for TC, 527.18–565.98 µg/disc for OTC and 1320.12–1320.86 µg/disc for CTC, respectively. The uptake efficiencies were 94.21–111.12, 71.25–88.44 and 76.10–86.62% for TC, OTC and CTC, respectively, with the TCs concentration of 0.05–10 mg/L. The adsorption kinetics of TCs could be described with a pseudo-second-order model (POSM, R2 >0.97). According to the result of adsorption kinetics, the adsorption rate of TCs in the binding gel was not as fast as that of heavy metals, suggesting that the TCs concentrations at the boundary of binding gels in the o-DGT devices could not decrease to zero. After correction of the boundary concentration, the FDCs accounted for 30.30–56.90, 48.10–64.68 and 16.55–50.16% for TC, OTC and CTC, respectively, while their concentrations ranged from 0.2 to 10.0 mg/L. Our results suggested that SPE packing might be an ideal adsorption material for o-DGT binding gels, and that adsorption kinetics should be corrected when calculating the FDCs of organic pollutants.

Development of Solid Phase Extraction Method Based on Ion Imprinted Polymer for Determination of Cr(III) Ions by ETAAS in Waters

In this work, a new solid phase extraction method for the determination of chromium species in water samples by electrothermal atomic absorption spectrometry was developed. For selective separation of Cr(III) ions under dynamic conditions, two ion imprinted polymers containing Cr(III)-1,10-phenanthroline complex (Cr(III)-phen) were prepared with the use of one (styrene, ST) or two (styrene and 4-vinylpyridine, ST-4VP) functional monomers. The physicochemical properties of those solid sorbents towards Cr(III) ions were studied and compared. It was found that Cr(III) ions were retained on the Cr(III)-phen-ST and Cr(III)-phen-ST-4VP polymers with high efficiency and repeatability (91.6% and 92.9%, RSD &lt; 2%) from solutions at pH 4.5. The quantitative recovery of the analyte (91.7% and 93.9%, RSD &lt; 4%) was obtained with 0.1 mol/L EDTA solution. The introduction of 4VP, an additional functional monomer, improved selectivity of the Cr(III)-phen-ST-4VP polymer towards Cr(III) ions in the presence of Cu(II), Mn(II) and Fe(III) ions, and slightly decreased the sorption capacity and stability of that polymer. The accuracy of procedures based on both polymeric sorbents was proved by analyzing the standard reference material of surface water SRM 1643e. The method using the Cr(III)-phen-ST polymer was applied for determining of Cr(III) ions in tap water and infusion of a green tea.

Equilibrium sorption properties of cholesterol surface-imprinted Se-containing polymeric sorbents synthesized by Pickering emulsion polymerization

Equilibrium sorption properties of cholesterol surface-imprinted Se-containing polymeric sorbents synthesized by Pickering emulsion polymerization