A novel carbonized polymer dots-based molecularly imprinted polymer with superior affinity and selectivity for oxytetracycline removal.

Molecularly imprinted polymers (MIPs) synthesized from chain functional monomers are restricted by spatial extension and exhibit relatively poor affinity and selectivity; this results in unsatisfactory applications in complex media. In this study, we prepared unique spherical carbonized polymer dots (CPDs-OH) via the incomplete carbonization of 1-allyl-3-vinylimidazolium bromide and ethylene glycol, and used it as a functional monomer to prepare a newly imprinted polymer (CPDs-OH@MIP) in aqueous media. As a result, the CPDs-OH@MIP exhibited effective recognition of oxytetracycline with an impressive imprinting factor of 6.17, surpassing MIPs prepared with chain functional monomers (1-3). Furthermore, CPDs-OH@MIP exhibited excellent adsorption for oxytetracycline (278.52 mg g-1) and achieved equilibrium in 30 min, with stronger resistance to coexisting cations, anions, and humic acid. Compared to other MIPs and adsorbents, the recognition performance of CPDs-OH@MIP improved 2-4 times; this polymer could remove >92.1% of oxytetracycline in real water samples with at least 10 cycle times. CPDs-OH@MIP prepared using the special spherical monomer forms a denser structure with fewer nonimprinted regions and precisely imprinted sites, remarkably improving the affinity and selectivity of MIPs combined via hydrogen bonds and electrostatic and π-π interactions. Our proposed strategy provides an effective basis for breakthroughs in the practical application of MIPs.

Surface imprinted polymer on a metal-organic framework for rapid and highly selective adsorption of sulfamethoxazole in environmental samples.

The demand for the removal of pollutants in aqueous solution has triggered extensive studies to optimize the performance of adsorbents, but the adsorption rate and selectivity of adsorbents have been overlooked. Hierarchically ordered porous vinyl-functionalized UIO-66 was used as supporter to prepare a surface molecular imprinted polymer (MIP-IL@UIO-66). The UIO-66 with large specific surface area significantly increased the number of active site of polymer, and so the MIP-IL@UIO-66 can achieve the rapid and highly selective adsorption of sulfamethoxazole (SMZ) in water. The structure and morphology of MIP-IL@UIO-66 was examined using scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, thermogravimetry, X-ray photoelectron spectroscopy, and X-ray powder diffraction. Results indicate that the presented MIP-IL@UIO-66 has an ultrafast equilibrium rate (equilibrium time, 10 min), large adsorption capability (maximum capacity, 284.66 mg g-1), excellent adsorption selectivity (selectivity coefficient, 11.36), and good reusability (number of cycles, 5 times) via equilibrium adsorption experiments. Subsequently, as a novel solid phase extraction (SPE) adsorbent, the adsorption performance of SMZ onto MIP-IL@UIO-66 was better than that of a commercial SPE adsorbent. A MISPE column combined with high-performance liquid chromatography (HPLC) was presented to detect SMZ in water, soil, egg, and pork samples with recoveries of 91-106%. Hydrogen bonds, electrostatic and π-π interactions, and molecular memory were attributed to recognizing the SMZ of MIP-IL@UIO-66.

A highly sensitive and selective method for the determination of ceftiofur sodium in milk and animal-origin food based on molecularly imprinted solid-phase extraction coupled with HPLC-UV.

The effective analysis of cephalosporin antibiotics in food animals has attracted considerable attention. Herein, a high-performance liquid chromatograph equipped with a UV method based on molecularly imprinted-solid phase extraction (MISPE-HPLC-UV) was developed for preconcentration, cleanup and determination of ceftiofur sodium (CTFS) in food samples. In this method, an eco-friendly molecularly imprinted polymer (MIP) was synthesized and employed as an adsorbent, which exhibited excellent selectivity towards CTFS in water, and adsorption equilibrium could be reached within 1 h. Under the optimized conditions, good linearity was obtained for CTFS in the range of 0.005-1.0 mg L-1 with a lower LOD of 0.0015 mg L-1, and the average recoveries were higher than 91.9% (RSD less than 8.5%) at three spiked levels in milk, chicken, pork and beef samples. After 20 cycles, the recovery of the MISPE cartridge for CTFS was still higher than 95%, which proved that the MISPE-HPLC-UV method was highly sensitive and selective for the analysis of CTFS in food samples.

A novel fluorescent probe based on N, B, F co-doped carbon dots for highly selective and sensitive determination of sulfathiazole.

The widespread occurrence of sulfathiazole (STZ) in the environment has raised concerns regarding the potential risks to ecosystem and human health. Thus, there is a need to develop facile and efficient methods for monitoring STZ. In this study, a novel fluorescent probe, based on N, B, F co-doped carbon dots (N, B, F-CDs), was developed for the highly sensitive and selective determination of STZ. The fluorescent N, B, F-CDs were prepared via a one-step hydrothermal method using malonate and 1-allyl-3-vinylimidazolium tetrafluoroborate ionic liquid as precursors. The obtained N, B, F-CDs exhibited excellent fluorescence response toward STZ due to the inner filter effect (IFE), which caused the fluorescence to be quenched. The fluorescent probe allowed the STZ concentration to be accurately determined with a low detection limit of 5.5 ng mL-1 in two wide linear ranges of 0.008-10 µg mL-1 and 10-45 µg mL-1. The practicability of the fluorescent probe was further validated in river water, soil, milk, and egg samples, and the satisfactory spiked recoveries of STZ ranged from 96.1 to 101.6%. The proposed fluorescent probe based on N, B, F-CDs can be easily prepared and possess high selectivity and sensitivity, thereby displaying its tremendous potential for the identification and determination of STZ in the environment.

One-step synthesis of functional metal organic framework composite for the highly efficient adsorption of tylosin from water.

Functional metal organic framework composite can effectively remove antibiotics from environmental water samples. However, designing excellent adsorbents with multiple active sites via a rapid one-step method is still a challenging problem. A novel metal organic framework composite (UiO-66-NH2-AMPS) was synthesized through one-step polymerization by adding functional monomer 2-acrylamide-2-methylpropanesulfonic acid (AMPS) during the preparation of UiO-66-NH2. The microstructure and morphology of the UiO-66-NH2-AMPS composite were characterized, and the adsorption performance towards tylosin (TYL) in water was explored by equilibrium adsorption experiment. The results illustrated that the adsorption equilibrium can be reached within 1 h, and the maximum binding amount of UiO-66-NH2-AMPS for TYL was 161.60 mg g-1, which was approximately 2.1-329 times of that of the other adsorbents. The pseudo second-order kinetic and Liu isotherm model were suitable for the adsorption process, and thermodynamic study displayed that the adsorption of UiO-66-NH2-AMPS composite for TYL is spontaneous and endothermal. The infrared and X-ray photoelectron spectra exhibited that hydrogen bond and electrostatic interaction were the primary recognition force for TYL. The UiO-66-NH2-AMPS composite have been successfully applied to remove TYL from environmental water. After 5 cycles, the removal efficiency of UiO-66-NH2-AMPS was still above 91.30%.

One-step polymerization of hydrophilic ionic liquid imprinted polymer in water for selective separation and detection of levofloxacin from environmental matrices.

A novel green hydrophilic levofloxacin imprinted polymer was presented via one-step polymerization in water using ionic liquid 1,6-hexa-3,3'-bis-1-vinylimidazolium bromine with multiple hydrophilic groups and 2-hydroxyethyl methacrylate as a co-functional monomer. Adsorption experiment revealed that the ionic liquid significantly improved the water compatible of imprinted polymer, and the excellent recognition of molecularly imprinted polymer for levofloxacin in water corresponds to the synergetic effect of H-bonding and the electrostatic and π-π interactions between the levofloxacin and co-functional monomer. Furthermore, the adsorption process of the imprinted material towards levofloxacin fitted the Langmuir model, and the maximum binding amount of levofloxacin onto the imprinted and corresponding non-imprinted polymer were 16.45 and 6.82 mg/g at 25°C, respectively. After optimizing the parameters affecting solid phase extraction performance, an enrichment and determination system was achieved to separate and detect levofloxacin from water and sediment samples with recoveries that ranged from 83.67 to 101.33% and relative standard deviation of less than 5.59%.

Water compatible imprinted polymer prepared in water for selective solid phase extraction and determination of ciprofloxacin in real samples.

A novel water compatible ciprofloxacin imprinted polymer is synthesized in water via a green, non-toxic and environmentally friendly polymerization process. Hydrophilic groups, including anionic chlorine, hydroxyl, and carbonyl oxygen provided by a bifunctional monomer comprising 1-allyl-3-vinylimidazole chloride and 2-hydroxyethyl methacrylate, are introduced into the imprinted material, which allows the polymer to interact strongly with imprinting molecule via hydrogen bonds, electrostatic and π-π dipole interactions in aqueous solution. Rebinding experiments show that the obtained molecularly imprinted polymer (MIP) presents special molecular recognition towards quinolone antibiotics (ciprofloxacin, levofloxacin and pefloxacin mesylate) in aqueous matrices. The adsorption process of ciprofloxacin on MIP and non-imprinted polymer (NIP) substrates involves spontaneous exothermic reactions, and the maximum rebinding capacities of ciprofloxacin on MIP and NIP at 25 °C are 19.96 and 8.86 mg g-1, respectively. The excellent selectivity and hydrophilicity of this imprinted polymer makes it suitable for use as an adsorbent in solid phase extraction. Under the optimized conditions, the presented MIP-SPE protocol exhibits a wide linear range between 0.29 and 1.47 × 105 µg L-1 and has been successfully applied for the separation and enrichment of trace ciprofloxacin in real water, soil and pork samples with satisfactory recoveries of 87.33-102.50%. The proposed study implies the promising prospect of this green and water compatible MIP in highly effective recognition and separation of trace quinolones in complex matrics.

An ionic liquid functionalized polymer for simultaneous removal of four phenolic pollutants in real environmental samples.

An ionic liquid functionalized polymer (IL-P) was prepared feasibly and simply by grafting1-butyl-3-vinylimidazolium bromide onto the silica surface. The IL-P was fully characterized, and the results showed that IL-P has a rough surface with a lower specific surface area (205.49 m2 g-1), and the involvement of ionic liquid significantly improved the adsorption performance of IL-P. The pH, initial concentration, adsorption time and temperature were investigated to discuss the adsorption behaviors of IL-P in aqueous solution. The adsorption process of 2,4-dichlorophenol (2,4-DCP), bisphenol A (BPA) and 2,4-dinitrophenol (2,4-DNP) onto IL-P better fitted the pseudo-second-order model, while that of 2-isonaphthol (2-NP) followed the pseudo-first-order model. The adsorption behaviors of IL-P towards 2,4-DCP and 2,4-DNP fitted well with Liu isotherm model, and that of BPA and 2-NP can be described by Langmuir model. The maximum adsorption capacities of 2,4-DCP, BPA, 2,4-DNP and 2-NP bound on IL-P was 239.7, 68.39, 56.86 and 64.28 mg g-1, respectively, and the adsorption of IL-P is a spontaneous physical process. Comparing with other adsorbent, the as-prepared IL-P showed excellent recognition ability towards the phenolic compounds and can be applied to adsorb and remove trace 2,4-DCP, 2-NP, 2,4-DNP and BPA simultaneously in complicated wastewater and soil samples.

A new ionic liquid surface-imprinted polymer for selective solid-phase-extraction and determination of sulfonamides in environmental samples.

Toward improving the selective adsorption performance of molecularly imprinted polymers in strong polar solvents, in this work, a new ionic liquid functional monomer, 1-butyl-3-vinylimidazolium bromide, was used to synthesize sulfamethoxazole imprinted polymer in methanol. The resulting molecularly imprinted polymer was characterized by Fourier transform infrared spectra and scanning electron microscopy, and the rebinding mechanism of the molecularly imprinted polymer for sulfonamides was studied. A static equilibrium experiment revealed that the as-obtained molecularly imprinted polymer had higher molecular recognition for sulfonamides (e.g., sulfamethoxazole, sulfamonomethoxine, and sulfadiazine) in methanol; however, its adsorption of interferent (e.g., diphenylamine, metronidazole, 2,4-dichlorophenol, and m-dihydroxybenzene) was quite low. 1 H NMR spectroscopy indicated that the excellent recognition performance of the imprinted polymer was based primarily on hydrogen bond, electrostatic and π-π interactions. Furthermore, the molecularly imprinted polymer can be employed as a solid phase extraction sorbent to effectively extract sulfamethoxazole from a mixed solution. Combined with high-performance liquid chromatography analysis, a valid molecularly imprinted polymer-solid phase extraction protocol was established for extraction and detection of trace sulfamethoxazole in spiked soil and sediment samples, and with a recovery that ranged from 93-107%, and a relative standard deviation of lower than 9.7%.