Preparation and characterization of electro-spun nanofiber membranes and their possible applications in water treatment

More than 80 years ago, artificial materials with molecular recognition sites emerged. The application of molecular imprinting to membrane separation has been studied since 1962. Especially after 1990, such research has been intensively conducted by membranologists and molecular imprinters to understand the advantages of each technique with the aim of constructing an ideal membrane, which is still an active area of research. The present review aims to be a substantial, comprehensive, authoritative, critical, and general-interest review, placed at the cross section of two broad, interconnected, practical, and extremely dynamic fields, namely, the fields of membrane separation and molecularly imprinted polymers. This review describes the recent discoveries that appeared after repeated and fertile collisions between these two fields in the past three years, to which are added the worthy acknowledgments of pioneering discoveries and a look into the future of molecularly imprinted membranes. The review begins ...

Molecularly Imprinted Membranes: Past, Present, and Future

Synthesis and characterization of core–shell magnetic molecularly imprinted polymers for solid-phase extraction and determination of Rhodamine B in food

Herein, we report an effective strategy based on coordination-induced signaling by introducing a rhodamine B group linkage into squaraine–diamine dyads as a reversible switch. The optimized design, synthesis and application of a new optical squaraine–bis(rhodamine-B) chemosensor ( SRB ) as an ‘off–on’ fluorescent probe for the detection of Hg 2+ ions were investigated. SRB exhibited high selectivity toward Hg 2+ in the presence of various metal ions, such as Al 3+ , Ag + , Co 2+ , Cs + , Cu 2+ , Fe 3+ , K + , Li + , Mg 2+ , Na + , Ni 2+ , Pb 2+ , and Zn 2+ , and the resulting complex [ SRB –Hg 2+ ] was investigated using UV–vis and fluorescence spectroscopy in acetonitrile (CH 3 CN). The ‘off–on’ fluorescence and color signal change of the probe are based on a Hg 2+ -triggered domino reaction that employs the open-ring form of rhodamine spirolactam to regain the conjugated system of the rhodamine skeleton. The mechanism for the opening of the rhodamine spirolactam ring induced by Hg 2+ binding and the 1:1 stoichiometric structure of SRB and Hg 2+ were confirmed using a Job's plot estimation, optical titration and FT-IR. Subsequently, a SRB –Hg 2+ complex chemosensor was employed to detect CN − in the presence of different anions, such as Br − , CH 3 COO − or AcO − , Cl − , ClO 4 − , F − , HPO 4 − , HSO 4 − , I − , N 3 − , NO 3 − , PF 6 − and SCN − , in acetonitrile. In addition, this sensor exhibited highly selective and sensitive recognition of cyanide ions upon the addition of Hg 2+ with a color change back to colorless in the same solution. Finally, SRB was successfully applied with the PEGDMA polymer to sense Hg 2+ ions, which was analyzed using fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.

A highly selective fluorescent chemosensor for Hg2+ based on a squaraine–bis(rhodamine-B) derivative: Part II

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/adfm.202001955

Molecularly Imprinted Polymers and Electrospinning: Manufacturing Convergence for Next‐Level Applications

A simple method for the formation of molecularly imprinted membrane of Rhodamine B (RhB) was developed by electrospinning. RhB molecularly imprinted microspheres were produced by precipitation polymerization using RhB, acrylamide, ethylene glycol dimethacrylatea (EGDMA), azobisisobutyronitrile (AIBN) and acetonitrile as template, functional monomer, cross-linking agent, initiator and porogen, respectively. Then molecularly imprinted membranes (MIMs) were produced via electrospinning technique with polyethylene terephthalate (PET) as the matrix polymer. The as-prepared nanofiber membranes were characterized by scanning electron microscopy (SEM). Optimization studies with the aim to enhance the MIP selection adsorption were carried out with respect to the amount of membrane, pH and adsorption time. Linear range and detection limit were 0.01 ~ 20 μmol/L and 2.0 × 10-3 μmol/L, respectively. HPLC analysis showed that in the optimized conditions of separation and enrichment, the recovery rate can reach 97.8% ~ 117.1%, relative standard deviation (n = 3) was 1.36% ~ 2.19% in employing MIMs to the RhB simulated water samples. The results showed that the imprinted polymer exhibited higher affinity for Rhodamine B compared to non-molecularly imprinted polymers membranes (NIMs) and molecularly imprinted particles (MIP).

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Xiulan Lei

Papers

Electrospun Nanofiber Membranes Containing Molecularly Imprinted Polymer (MIP) for Rhodamine B (RhB)