Selective Adsorption and Purification of the Acteoside in Cistanche tubulosa by Molecularly Imprinted Polymers

This review summarizes the major advances since 2012 in highly permeable and CO 2 -selective polymer-based membrane materials. Membrane processes have evolved as a competitive approach in CO 2 separations compared with absorption and adsorption processes, due to their inherent attributes such as energy-saving and continuous operation. High permeability membrane materials are crucial to efficient membrane processes. Among existing membrane materials for CO 2 separations, polymer-based materials have some intrinsic advantages such as good processability, low price and a readily available variety of materials. In recent years, enormous research effort has been devoted to the use of membrane technology for CO 2 separations from diverse sources such as flue gas (mainly N 2 ), natural gas (mainly CH 4 ) and syngas (mainly H 2 ). Polymer-based membrane materials occupy the vast majority of all the membrane materials. For large-scale CO 2 separations, polymer-based membrane materials with high CO 2 permeability and good CO 2 /gas selectivity are required. In 2012, we published a Perspective review in Energy & Environmental Science on high permeability polymeric membrane materials for CO 2 separations. Since then, more rapid progress has been made and the research focus has changed significantly. This review summarises the advances since 2012 on high permeability polymer-based membrane materials for CO 2 separations. The major features of this review are reflected in the following three aspects: (1) we cover polymer-based membrane materials instead of purely polymeric membrane materials, which encompass both polymeric membranes and polymer–inorganic hybrid membranes. (2) CO 2 facilitated transport membrane materials are presented. (3) Biomimetism and bioinspired membrane concepts are incorporated. A number of representative examples of recent advances in high permeability polymer-based membrane materials is highlighted with some critical analysis, followed by a brief perspective on future research and development directions.

A novel multi-permselective mixed matrix membrane (MP-MMM) is developed by incorporating versatile fillers functionalized with ethylene oxide (EO) groups and an amine carrier into a polymer matrix. The as-prepared MP-MMMs can separate CO2 efficiently because of the simultaneous enhancement of diffusivity selectivity, solubility selectivity, and reactivity selectivity. To be specific, MP-MMMs were fabricated by incorporating polyethylene glycol- and polyethylenimine-functionalized graphene oxide nanosheets (PEG-PEI-GO) into a commercial low-cost Pebax matrix. The PEG-PEI-GO plays multiple roles in enhancing membrane performance. First, the high-aspect ratio GO nanosheets in a polymer matrix increase the length of the tortuous path of gas diffusion and generate a rigidified interface between the polymer matrix and fillers, enhancing the diffusivity selectivity. Second, PEG consisting of EO groups has excellent affinity for CO2 to enhance the solubility selectivity. Third, PEI with abundant primary, secondary, and tertiary amine groups reacts reversibly with CO2 to enhance reactivity selectivity. Thus, the as-prepared MP-MMMs exhibit excellent CO2 permeability and CO2/gas selectivity. The MP-MMM doped with 10 wt % PEG-PEI-GO displays optimal gas separation performance with a CO2 permeability of 1330 Barrer, a CO2/CH4 selectivity of 45, and a CO2/N2 selectivity of 120, surpassing the upper bound lines of the Robeson study of 2008 (1 Barrer = 10(-10) cm(3) (STP) cm(-2) s(-1) cm(-1) Hg).

This paper presents an overview of the recent applications of molecularly imprinted polymers (MIPs) to sample preparation. The review is thought to cover analytical procedures for extraction of contaminants (mainly illegal/noxious organic compounds) from food and environmental matrices, with a particular focus on the various pre-concentration/cleanup techniques, that is offline and online solid-phase extraction (SPE), dispersive SPE (d-SPE), magnetic SPE (MSPE), solid-phase microextraction (SPME) and stir-bar sorptive extraction (SBSE), applied before instrumental quantification. The selectivity and extraction efficiency of MIP-based sorbent phases are critically discussed, also in relation to the physical-chemical properties resulting from the synthetic procedures. A variety of molecularly imprinted sorbents is presented, including hybrid composites embedding carbon nanomaterials and ionic liquids. The analytical performance of MIP materials in sample preparation is commented as function of the complexity of the matrix, and it is compared to that exhibited by (commercial) aspecific and/or immunosorbent phases.