Enhanced permeation performance of polyether-polyamide block copolymer membranes through incorporating ZIF-8 nanocrystals

Membrane-based CO_2 separation is a promising alternative in terms of energy and environmental issues to other conventional techniques. Polyether-polyamide block copolymer(Pebax) membranes are promising for CO_2 separation because of their excellent selectivity, but limited by their moderate gas permeability. In this study,fresh-prepared zeolitic imidazolate framework-8(ZIF-8) nanocrystals were integrated into the Pebax?1657matrices to form mixed matrix membranes. The resulting membrane exhibits significantly improved CO_2permeability(as high as 300% increase), without the sacrifice of the selectivity, to the pristine polymer membrane. Several physical characterization techniques were employed to confirm the good interfacial interaction between ZIF-8 fillers and Pebax matrices. The effect of added ZIF-8 fillers on the transport mechanism through MMMs is also explored. Mixed-gas permeation for both CO_2/N_2 and CO_2/CH_4 was also evaluated. The separation performance for CO_2/CH_4 mixtures on the ZIF-8/Pebax MMMs is very close to the Roberson upper bound, and thus is technologically attractive for purification of natural gas.

Fe-TiO_2 and Fe_2O_3 quantum dots co-loaded on MCM-41 for removing aqueous rose bengal by combined adsorption/photocatalysis

Adsorption and photodegradation are promising approaches for removing organic pollutions.In this study,we combined these two processes by co-loading Fe-TiO2 and Fe2O3 quantum dots(QDs)on porous MCM-41,using a simple hydrolysis method.X-ray diffraction,high-resolution transmission electron microscopy,and X-ray photoelectron spectroscopy results indicated that Fe-TiO2 QDs are formed at low Fe precursor concentrations,while additional Fe2O3 QDs are formed at higher Fe precursor concentrations.The Fe2O3 and Fe-TiO2 QDs impart high adsorption capacity and high photoactivity to the porous MCM-41,respectively.Thus,their combination results in a synergic effect of the adsorption and photodegradation.The highest-performing sample exhibits excellent performance in removing rose bengal from aqueous solution.

Biochar-based slow-release of fertilizers for sustainable agriculture:A mini review

Increasing global population and decreasing arable land pose tremendous pressures to agricultural production.The application of conventional chemical fertilizers improves agricultural production,but causes serious environmental problems and significant economic burdens.Biochar gains increasing interest as a soil amendment.Recently,more and more attentions have been paid to biochar-based slowrelease of fertilizers(SRFs)due to the unique properties of biochar.This review summarizes recent advances in the development,synthesis,application,and tentative mechanism of biochar-based SRFs.The development mainly undergoes three stages:(i)soil amendment using biochar,(ii)interactions between nutrients and biochar,and(iii)biochar-based SRFs.Various methods are proposed to improve the fertilizer efficiency of biochar,majorly including in-situ pyrolysis,co-pyrolysis,impregnation,encapsulation,and granulation.Considering the distinct features of different methods,the integrated methods are promising for fabricating effective biochar-based SRFs.The in-depth understanding of the mechanism of nutrient loading and slow release is discussed based on current knowledge.Additionally,the perspectives and challenges of the potential application of biochar-based SRFs are described.Knowledge surveyed from this review indicates that applying biochar-based SRFs is a viable way of promoting sustainable agriculture.

CuAlCl4 doped MIL-101 as a high capacity CO adsorbent with selectivity over N2

A CuAlCl4 doped metal organic framework, CuAlCl4@MIL-101, was prepared by introducing CuAlCl4 into the pores of MIL-101 for the selective adsorption of CO over N2. The CuAlCl4 molecules were evenly distributed into various pores sizes and did not change the intrinsic structure of the MIL-101. Isotherms for CO and N2 adsorption at 298 K showed that the CO capacity on CuAlCl4@MIL-101 was much higher than that on virgin MIL-101, whereas the N2 capacity decreased. The selectivity for CO over N2 improved from 4.64 to 31.5 at 298 K and 1 bar. The CuAlCl4@MIL-101 adsorbent displayed outstanding CO adsorption stability and the adsorbent could be regenerated by applying a simple vacuum of 4 mmHg.

integrated structure for recognition of different joint motion states with the assistance of a deep learning algorithm

Accurate motion feature extraction and recognition provide critical information for many scientific problems.Herein,a new paradigm for a wearable seamless multimode sensor with the ability to decouple pressure and strain stimuli and recognize the different joint motion states is reported.This wearable sensor is integrated into a unique seamless structure consisting of two main parts(a resistive component and a capacitive component)to decouple the different stimuli by an independent resistance-capacitance sensing mechanism.The sensor exhibits both high strain sensitivity(GF=7.62,0-140%strain)under the resistance mechanism and high linear pressure sensitivity(S=3.4 kPa^(-1),0-14 kPa)under the capacitive mechanism.The sensor can differentiate the motion characteristics of the positions and states of different joints with precise recognition(97.13%)with the assistance of machine learning algorithms.The unique integrated seamless structure is achieved by developing a layer-bylayer casting process that is suitable for large-scale manufacturing.The proposed wearable seamless multimode sensor and the convenient process are expected to contribute significantly to developing essential components in various emerging research fields,including soft robotics,electronic skin,health care,and innovative sports systems applications.

Improved dispersion performance and interfacial compatibility of covalent-grafted MOFs in mixed-matrix membranes for gas separation

Mixed-matrix membranes(MMMs)have received much attention due to their processable advantages of polymer and high permeability and/or selectivity of porous metal-organic frameworks(MOFs)fillers.However,the interfacial defects caused by poor interaction between MOFs with polymers and the agglomeration phenomenon caused by uneven dispersion of MOFs are common problems in mixed-matrix membranes.Currently,the priming protocol is one of solutions to the above problems,but it cannot precisely regulate the dispersion of particles and the interfacial compatibility between two phases.Herein,covalent grafting of polyimide 6FDA-Durene onto the surface of UiO-66-NH2 can mitigate the aggregation of fillers inside the polymeric matrices and improve the interfacial interaction between two phases,thus significantly improving the CO_(2)/CH_(4)separation performance on the as-synthesized MMMs.The explored gas transport mechanism indicated that the improved separation was due to the raise of solubility selectivity.Furthermore,the stronger covalent bond between fillers and polyimide than physical interaction of priming protocol also endows the improved anti-plasticization phenomenon for CO_(2)/CH_(4)separation.