Dual-imprinted mixed matrix membranes for selective recognition and separation: A synergetic imprinting strategy based on complex initiation system

Fabrication of magnetic hydrophilic imprinted polymers via two-step immobilization approach for targeted detecting bisphenol A

Molecularly imprinted polymer with water-compatibility for effective separation and enrichment of targeted trace pollutants from complicated matrix has captured extensive attention in terms of their high selectivity and matrix compatibility. This study focuses on modified β-cyclodextrin is used as a hydrophilic functional monomer to develop magnetic molecularly imprinted polymers (MMIPs). MMIPs were prepared using Fe3O4 nanoparticles as carriers and bisphenol A (BPA) as templates using a two-step fixation strategy and surface imprinting technology. The structural characteristic and binding properties of the prepared MMIPs were thoroughly studied. The MMIPs exhibited high crystallinity, high adsorption capacity, fast rebinding rate, remarkable selectivity and distinguish reusability. In addition, through magnetic solid-phase extraction separation technology and high-performance liquid chromatography ultraviolet quantitative detection technology, MMIPs are used for selective enrichment and detection of BPA in complex media such as environmental water and milk. This work provides a new route to construct the hydrophilic molecularly imprinted materials and a new sight on developing more effective sample pretreatment strategies for monitoring targeted pollution in complicated aqueous media.

Optimization and verification of selective removal of organophosphate esters from wastewater by molecularly imprinted adsorbent

Tributyl phosphate (TNBP), a new type of flame retardant, is an emerging pollutant and has been frequently detected in various matrices such as wastewater. Efficient removal of TNBP is critical for wastewater treatment. In this study, molecularly imprinted polymer (MIP) was prepared using precipitation polymerization for selective adsorption of TNBP. The results showed that MIP had a porous structure and formed effective imprinting cavities, which was primarily responsible for its superior adsorption ability. The adsorption of TNBP by MIP was carried out following both the pseudo-secondary kinetic model and the Langmuir isothermal adsorption model. MIP adsorbed TNBP rapidly and reached adsorption equilibrium within 30 min with 923 μmol g-1 at 298 K. The adsorption capacity and adsorption rate of MIP were respectively 2 and 5.49 times those of non-molecularly imprinted polymers. In addition, MIP could effectively counter disturbances from external parameters like temperature and pH, exhibiting strong environmental flexibility. MIP can specifically adsorb organophosphate esters, and can selectively adsorb TNBP under the interference of coexisting contaminants such as1,3-diphenylguanidine and isazofos. In actual bodies of water, MIP's highly selective adsorption of TNBP retains its advantage. The selective adsorption of MIP was mainly due to the common phosphate skeleton, and the specific substituent of organophosphate esters played an important role in the imprinting process. Hydrogen bonding might be involved in the polymerization process of TNBP with acrylamide and the adsorption process of TNBP by MIP.MIP exhibited good reuse efficiency, the total adsorption capacity decreased by no more than 25% after 7 reuse cycles. This study provides a simple and efficient method for selective removal of organophosphate from wastewater.

Dummy molecularly imprinted polymers-agarose gel mixed matrix membrane for extraction of amphetamine-type stimulants in wastewater and urine

Dummy molecularly imprinted polymers (DMIPs) with high selectivity for amphetamine-type stimulants (ATSs) were synthesized using synephrine molecule as a dummy template. The polymers were irregularly massive with a specific surface area of 330 m2g-1. Adsorption experiments found that the imprinting factors for five ATSs (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and 3,4-methylenedioxy-N-ethylamphetamine) were 2.3∼3.7. The DMIPs-agarose gel mixed matrix membranes (MMMs) were further prepared by incorporating DMIPs in the agarose matrix. MMMs were used to extract five ATSs from wastewater and urine samples. Extraction conditions such as membrane matrix, sample pH, dissolved organic matter content, extraction time, and elution reagent were optimized. Under optimal conditions, the developed MMMs-HPLC-MS/MS method exhibited low limits of detection (0.1∼3.0ng L-1), satisfactory recoveries (91.7∼100%), and good repeatability (RSD<7%, n=3). It was then successfully applied to ATSs analysis in wastewater and urine samples. Recoveries of ATSs in spiked wastewater and urine were 82.0∼98.4% and 82.3∼95.7%, respectively. Moreover, compared with other methods, the present method possessed the advantages of high quantitative ability, suitable for typical environmental conditions, and low application cost. The above results suggested that the developed MMMs-HPLC-MS/MS method could be used as a feasible strategy to extract and determine trace ATSs in wastewater and urine samples.

Next-generation graphene oxide additives composite membranes for emerging organic micropollutants removal: Separation, adsorption and degradation

In the past two decades, membrane technology has attracted considerable interest as a viable and promising method for water purification. Emerging organic micropollutants (EOMPs) in wastewater have trace, persistent, highly variable quantities and types, develop hazardous intermediates and are diffusible. These primary issues affect EOMPs polluted wastewater on an industrial scale differently than in a lab, challenging membranes-based EOMP removal. Graphene oxide (GO) promises state-of-the-art membrane synthesis technologies and use in EOMPs removal systems due to its superior physicochemical, mechanical, and electrical qualities and high oxygen content. This critical review highlights the recent advancements in the synthesis of next-generation GO membranes with diverse membrane substrates such as ceramic, polyethersulfone (PES), and polyvinylidene fluoride (PVDF). The EOMPs removal efficiencies of GO membranes in filtration, adsorption (incorporated with metal, nanomaterial in biodegradable polymer and biomimetic membranes), and degradation (in catalytic, photo-Fenton, photocatalytic and electrocatalytic membranes) and corresponding removal mechanisms of different EOMPs are also depicted. GO-assisted water treatment strategies were further assessed by various influencing factors, including applied water flow mode and membrane properties (e.g., permeability, hydrophily, mechanical stability, and fouling). GO additive membranes showed better permeability, hydrophilicity, high water flux, and fouling resistance than pristine membranes. Likewise, degradation combined with filtration is two times more effective than alone, while crossflow mode improves the photocatalytic degradation performance of the system. GO integration in polymer membranes enhances their stability, facilitates photocatalytic processes, and gravity-driven GO membranes enable filtration of pollutants at low pressure, making membrane filtration more inexpensive. However, simultaneous removal of multiple contaminants with contrasting characteristics and variable efficiencies in different systems demands further optimization in GO-mediated membranes. This review concludes with identifying future critical research directions to promote research for determining the GO-assisted OMPs removal membrane technology nexus and maximizing this technique for industrial application.

A recognition strategy combining effective boron affinity technology and surface imprinting to prepare highly selective and easily recyclable polymer membrane for separation of drug molecule

Cellulose acetate membrane (CAM) has become one of the most widely used membrane materials by virtue of stability and hydrophilicity. In this work, to achieve the aim of selective recognition and separation of drug molecule shikimic acid (SA), an effective recognition tactics was proposed by combining boron affinity technology with surface imprinting strategy based on cellulose acetate membrane with low price and biocompatibility. The supporting CAM material was prepared through the phase inversion technique by continuous adjustment of different factors including solvent type and kinds of pore-forming agents, and the optimal CAM with multistage structure and highly porosity was applied for the imprinting of SA. Then the imprinted polymer membrane (MIPs-CAM) was developed via boron affinity surface imprinting polymerization. Various methods (FT-IR, UV-vis, SEM, XPS, AFM and TGA) were used to characterize the structure, morphology, elemental composition, surface roughness and thermal property of the obtained membrane. The as-prepared MIPs-CAM showed homogeneous and abundant imprinted layer, good thermal stability. The batch adsorption results showed that the MIPs-CAM had fast adsorption kinetics, specific recognition ability, and the adsorption capacity could obtain 63.598 mg g^-1, which was two times higher than that of non-imprinted membrane (NIPs-CAM). The adsorption isotherms conformed to the Langmuir isotherm and the adsorption processes were spontaneous and endothermic. Additionally, the adsorption capacity of MIPs-CAM still reached 85% of the initial result after five cycles. The experimental results revealed that the molecularly imprinted membrane possessed the advantages of high selectivity and easy recovery compared with the traditional molecular imprinted polymers for SA separation. These results indicate that boron affinity MIPs-CAM with high performance will provide a promising platform for the separation and purification of other cis-diol drug molecules from environmental resources.

Magnetic Surface Molecularly Imprinted Polymer for Selective Adsorption of 4-Hydroxycoumarin

4-hydroxyl coumarin (HC), an important intermediate during the synthesis procedure of rodenticide and anti-cardiovascular drug, shows highly medicinal value and economic value. To achieve the efficient adsorption of HC from natural biological samples, a novel magnetic surface molecularly imprinted polymer (HC/SMIPs) was constructed by employing methacrylic acid (MAA) as functional monomer, organic silane modified magnetic particles as matrix carrier and HC as template molecule. Due to the numerous specific imprinted cavities on the HC/SMIPs, the maximum adsorption capacity of HC/SMIPs for 4-hydroxycoumarin could reach to 22.78 mg g⁻¹ within 20 min. In addition, HC/SMIPs exhibited highly selective adsorption for 4-hydroxycoumarin compared with other active drug molecules (osthole and rutin) and showed excellent regeneration performance. After 8 cycles of adsorption-desorption tests, the adsorption capacity of HC/SMIPs just slightly decreased by 6.64%. The efficient selective removal and easy recycle of 4-hydroxycoumarin from biological samples by HC/SMIPs made a highly promising to advance the application of imprinting polymers in complex practical environments.