In this study,the ZIF-8 membrane(ZIF-8/PP-g-MAH)is prepared by in situ synthesis of ZIF-8 on irradiation-pretreated polymer substrates to improve the uranium adsorption performance and address the recycling problems o...In this study,the ZIF-8 membrane(ZIF-8/PP-g-MAH)is prepared by in situ synthesis of ZIF-8 on irradiation-pretreated polymer substrates to improve the uranium adsorption performance and address the recycling problems of ZIF-8 powder.The effects of pH,contact time,and uranium concentration on the adsorption of ZIF-8/PP-g-MAH were investigated.Adsorption isotherm and kinetics analysis show that ZIF-8/PP-g-MAH has a high adsorption capacity of 478.5 mg/g,which is 1.26 times higher than that of ZIF-8,and a rapid adsorption equilibrium of 120 min,which is shortened to one-third of that required for ZIF-8(360 min).The adsorption process of ZIF-8/PP-g-MAH is consistent with that of the Langmuir isotherm and pseudo-second-order dynamic model.ZIF-8/PP-g-MAH also exhibits good selectivity for uranium in simulated seawater.The high adsorption performance of ZIF-8/PP-g-MAH is attributed to its membrane structure,which improves the utilization of coordination sites,including Zn-OH,C-N,and C=N.This study provides an efficient adsorption material for rapid uranium extraction,thus promoting the development of uranium extraction technologies.展开更多
Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membra...Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membrane layer, which usually requires complex surface modification or seeding. Herein, we demonstrate that a dual-layer asymmetric polymer support prepared by a simple spinning process is a good candidate for the preparation of ZIF-8 membrane. The inner layer of the support is an organic hollow fiber(PES) with finger-like pores, and the outer layer is a ZnO-PES composite layer with finger-like pores also. The ZnO-PES composite layer is expected to contain uniform ZnO crystals in the polymer matrix, i.e., the ZnO particles in the skin layer of the support are not easy to fall off. Under the induction of ZnO particles in the outer layers, continuous ZIF-8 membranes can be prepared by single in-situ crystallization, showing good adhesion to the supports. The obtained ZIF-8 membranes show a H_(2) permeance of 8.7 × 10^(-8)mol·m^(-2)·s^(-1)·Pa^(-1) with a H_(2)/N_(2) ideal separation selectivity of 18.0. The design and preparation of this dual-layer polymer support is expected to promote the large-scale application of MOF membranes on polymer supports.展开更多
Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further applicati...Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further application.In this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ growth.Firstly,a PVDF supporting membrane was modified to have a negative charge.Next,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic interaction.Afterwards,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 layer.Finally,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring method.Experimental results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX membrane.The optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.展开更多
文摘In this study,the ZIF-8 membrane(ZIF-8/PP-g-MAH)is prepared by in situ synthesis of ZIF-8 on irradiation-pretreated polymer substrates to improve the uranium adsorption performance and address the recycling problems of ZIF-8 powder.The effects of pH,contact time,and uranium concentration on the adsorption of ZIF-8/PP-g-MAH were investigated.Adsorption isotherm and kinetics analysis show that ZIF-8/PP-g-MAH has a high adsorption capacity of 478.5 mg/g,which is 1.26 times higher than that of ZIF-8,and a rapid adsorption equilibrium of 120 min,which is shortened to one-third of that required for ZIF-8(360 min).The adsorption process of ZIF-8/PP-g-MAH is consistent with that of the Langmuir isotherm and pseudo-second-order dynamic model.ZIF-8/PP-g-MAH also exhibits good selectivity for uranium in simulated seawater.The high adsorption performance of ZIF-8/PP-g-MAH is attributed to its membrane structure,which improves the utilization of coordination sites,including Zn-OH,C-N,and C=N.This study provides an efficient adsorption material for rapid uranium extraction,thus promoting the development of uranium extraction technologies.
基金supported by the National Natural Science Foundation of China (21978253)the Fundamental Research Funds for the Central Universities (226-2022-00020, 226-2022-00055)。
文摘Compared to inorganic supports, polymeric supports can offer additional benefits, e.g., easier processing and cheaper. However, the organic surface has weak adhesion to the zeolitic imidazolate frameworks(ZIFs) membrane layer, which usually requires complex surface modification or seeding. Herein, we demonstrate that a dual-layer asymmetric polymer support prepared by a simple spinning process is a good candidate for the preparation of ZIF-8 membrane. The inner layer of the support is an organic hollow fiber(PES) with finger-like pores, and the outer layer is a ZnO-PES composite layer with finger-like pores also. The ZnO-PES composite layer is expected to contain uniform ZnO crystals in the polymer matrix, i.e., the ZnO particles in the skin layer of the support are not easy to fall off. Under the induction of ZnO particles in the outer layers, continuous ZIF-8 membranes can be prepared by single in-situ crystallization, showing good adhesion to the supports. The obtained ZIF-8 membranes show a H_(2) permeance of 8.7 × 10^(-8)mol·m^(-2)·s^(-1)·Pa^(-1) with a H_(2)/N_(2) ideal separation selectivity of 18.0. The design and preparation of this dual-layer polymer support is expected to promote the large-scale application of MOF membranes on polymer supports.
基金the National Natural Science Foundation of China(22271022)Hubei Three Gorges Laboratory(SK212001).
文摘Metal-organic frameworks(MOFs)have gained attention in the development of MOFs/polymer hybrid membranes for pervaporation.However,the agglomeration of MOFs particles and interfacial defects limit its further application.In this study,we present a novel approach to fabricate a ZIF-8@PEBAX/PVDF nanocomposite membrane for removing thiophene from the model gasoline by combination of selfassembly and in-situ growth.Firstly,a PVDF supporting membrane was modified to have a negative charge.Next,positively charged zinc ions were attracted onto the negatively charged PVDF supporting membrane through electrostatic interaction.Afterwards,the Zinc ions deposited PVDF membrane was immersed into dimethylimidazole solution to form a uniform ZIF-8 layer.Finally,the ZIF-8 layer was coated with poly(ether-block-amide)(PEBAX)using the pouring method.Experimental results showed that the separating efficiency of the ZIF-8@PEBAX/PVDF nanocomposite membrane was improved significantly compared to that of pristine PEBAX membrane.The optimal permeation flux and enrichment factor of membrane were 27.80 kg(m^(2)h)^(-1)and 6.9,respectively.
