Recyclable hydrolyzed polymers of intrinsic microporosity-1/Fe_(3)O_(4) magnetic composites as adsorbents for selective cationic dye adsorption

Polymers of intrinsic microporosity shows great potential for dye adsorption and magnetic Fe_(3)O_(4) are easy to be separated.In this work,hydrolyzed polymers of intrinsic microporosity-1/Fe_(3)O_(4) composite adsorbents were prepared by phase inversion and hydrolysis process for cationic dye adsorption.The chemical structure and morphology of the composite adsorbents were systematically characterized by several characterization methods.Using methylene blue as the target dye,the influences of solution pH,contact time,initial dye concentration,and system temperature on the methylene blue adsorption process were investigated.The incorporation of Fe_(3)O_(4) particle into hydrolyzed polymers of intrinsic microporosity-1 endow the adsorbent with high magnetic saturation(20.7 emu·g^(–1))which allows the rapid separation of the adsorbent.Furthermore,the adsorption process was simulated by adsorption kinetics,isotherms and thermodynamics to gain insight onto the intrinsic adsorption mechanism.In addition,the composite adsorbents are able to selectively adsorb cationic dyes from mixed dyes solution.Hydrolyzed polymers of intrinsic microporosity/Fe_(3)O_(4) shows only a slight decrease for methylene blue adsorption after 10 adsorption/regeneration cycles,demonstrating the outstanding regeneration performance.The high adsorption capacity,outstanding regeneration ability,together with simple preparation method,endow the composite adsorbents great potential for selective removal of cationic dyes in wastewater system.

The synthesis of polymers of intrinsic microporosity (PIMs)

Polymers of intrinsic microporosity （PIMs） are a class of porous organic polymer （POP） that form microporous solids due to the inefficient packing of their rigid and contorted macromolecular chains. In contrast to other types of POP, PIMs are not comprised of a network of cross-linked covalent bonds so that they can be dissolved in organic solvents and processed into robust films, coatings or fibres. Here, over twelve years＇ accumulated research on the synthesis of PIMs is reviewed. To date, three types of polymerisation reaction have been used successfully to prepare PIMs of sufficient molecular mass to form robust self-standing films. These involve the formation of dibenzodioxin, Tr6ger＇s base and imide linkages between monomeric units. This rapid development of synthetic methods for preparing PIMs has been driven by their rich potential for numerous diverse applications and this synergistic relationship between synthesis and functionality is set to continue.

Surface functionalization of Polymers of Intrinsic Microporosity(PIMs)membrane by polyphenol for efficient CO_(2)separation

Membrane separation technology offers a green,efficient and energy-saving approach for biogas upgrading.Membranes with high selectivity and high permeability are the key to achieve high performance.Polymers of Intrinsic Microporosity(PIMs)materials have shown excellent gas permeability but low selectivity which limits their practical application.Herein,a polyphenol,tannic acid,was coated on the PIM-1 membrane surface by a facile dipping method to fabricate composite membranes.Tannic acid containing a large number of polar oxygencontaining groups(quinone,phenolic hydroxyl)self-polymerized on the membrane surface to form a CO2-philic,defect-free and thin layer.The CO2/CH4 selectivity of the resultant composite membranes was increased after tannic acid coating while the permeability remained comparable to or even higher than pristine PIM-1 membrane,exceeding the reported 2008 upper bound.

Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

Physical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications.A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols,such as methanol and ethanol.However,this procedure does not seem applicable at industrial level,and other strategies must be investigated.In this work,a regeneration method with alcohol vapors(ethanol or methanol)was developed to recover permeability of aged PIM-1 membranes,in comparison with the conventional soaking-in-liquid approach.The gas permeability and separation performance,before and post the regeneration methods,were assessed using a binary mixture of CO_(2) and CH_(4)(1:1,v:v).Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability,reaching a CO_(2) permeability>7000 barrer.

A bio-inspired O2-tolerant catalytic CO2 reduction electrode

The electrochemical reduction of CO2 to give CO in the presence of O2 would allow the direct valorization of flue gases from fossil fuel combustion and of CO2 captured from air. However, it is a challenging task because O2 reduction is thermodynamically favored over that of CO2. 5% O2 in CO2 near catalyst surface is sufficient to completely inhibit the CO2 reduction reaction. Here we report an O2-tolerant catalytic CO2 reduction electrode inspired by part of the natural photosynthesis unit. The electrode comprises of heterogenized cobalt phthalocyanine molecules serving as the cathode catalyst with >95% Faradaic efficiency(FE) for CO2 reduction to CO coated with a polymer of intrinsic microporosity that works as a CO2-selective layer with a CO2/O2 selectivity of $20. Integrated into a flow electrolytic cell, the hybrid electrode operating with a CO2 feed gas containing 5% O2 exhibits a FECOof 75.9% with a total current density of 27.3 mA/cm^2 at a cell voltage of 3.1 V. A FECO of 49.7% can be retained when the O2 fraction increases to 20%. Stable operation for 18 h is demonstrated. The electrochemical performance and O2 tolerance can be further enhanced by introducing cyano and nitro substituents to the phthalocyanine ligand.