On The Multiscale Structure and Morphology of PVDF‐HFP@MOF Membranes in The Scope of Water Remediation Applications

Abstract

Poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) is a highly versatile polymer used for water remediation due to its chemical robustness and processability. By incorporating metal‐organic frameworks (MOFs) into PVDF‐HFP membranes, the material can gain metal‐adsorption properties. It is well known that the effectiveness of these composites removing heavy metals depends on the MOF's chemical encoding and the extent of encapsulation within the polymer. In this study, it is examined how the micro to nanoscale structure of PVDF‐HFP@MOF membranes influences their adsorption performance for CrVI. To this end, the micro‐ and nanostructure of PVDF‐HFP@MOF membranes are thoroughly studied by a set of complementary techniques. In particular, small‐angle X‐ray and neutron scattering allow to precisely describe the nanostructure of the polymer‐MOF complex systems, while scanning microscopy and mercury porosimetry give a clear insight into the macro and mesoporosity of the system. By correlating nanoscale structural features with the adsorption capacity of the MOF nanoparticles, different degrees of full encapsulation‐based on the PVDF‐HFP processing and structuration from the macro to nanometer scale are observed. Additionally, the in situ functionalization of MOF nanoparticles with cysteine is investigated to enhance their adsorption toward HgII. This functionalization enhanced the adsorption capacity of the MOFs from 8 to 30 mg·g−1.

Linear Polyethyleneimine-Based and Metal Organic Frameworks (DUT-67) Composite Hydrogels as Efficient Sorbents for the Removal of Methyl Orange, Copper Ions, and Penicillin V

“…Considering the results from the functional assessment of our hydrogels, the adsorption kinetics and capacity of composite 15%D were always faster and higher than the observed ones for P1.5E, indicating a synergistic effect between both porous components, the hydrogel network structure and the micropore space of the DUT-67 nanoparticles. Similar synergic effects have been reported for polymer/MOF composite systems, where the kinetics and capacity of the systems overcame the average of their separate components [46,47].…”

The Application of Metal–Organic Frameworks in Water Treatment and Their Large-Scale Preparation: A Review

“…Therefore, in-depth research on the factors and reaction mechanisms that affect dye removal is crucial for enhancing the sustained application of MOF-containing membranes in dye decontamination. Similarly, in terms of removing heavy metal pollutants, membranes containing MOFs have the characteristics of fast equilibrium time, strong removal ability, and high selectivity towards target heavy metal ions, and can maintain excellent performance even under extreme environmental conditions [57][58][59][60]. To our knowledge, the reaction mechanism is mainly attributed to electrostatic interactions and pore-filling effects.…”

Orientation Growth of N-Doped and Iron-Based Metal–Organic Framework and Its Application for Removal of Cr(VI) in Wastewater

“…Among these methods, adsorption effectively concentrates Cr(VI) by two main forces, i.e., electrostatic interactions and coordination interactions, which are recognized as easy, fast, and highly efficient environmental protection techniques without secondary waste [ 18 , 19 , 20 , 21 , 22 , 23 ]. A wide variety of adsorption materials for the removal of Cr(VI) in wastewater have been reported, such as metal hydroxides [ 24 ], silica-based materials [ 25 , 26 , 27 ], biochar [ 28 ], activated carbon [ 29 , 30 , 31 ], various types of clay minerals [ 32 , 33 ], chitin and chitosan [ 34 , 35 , 36 ], zeolites [ 37 ], graphene oxide [ 38 , 39 , 40 ], amino-functionalized silica [ 41 ], amino-functionalized magnetic polymers [ 42 ] and metal–organic frameworks (MOFs) [ 43 , 44 , 45 , 46 ]. Among these adsorption materials, MOFs are a novel class of crystalline porous material with periodic network structure formed by the interconnection of inorganic metal centers (metal ions or metal clusters) and bridging organic ligands through self-assembly [ 43 , 44 , 45 ].…”

“…A wide variety of adsorption materials for the removal of Cr(VI) in wastewater have been reported, such as metal hydroxides [ 24 ], silica-based materials [ 25 , 26 , 27 ], biochar [ 28 ], activated carbon [ 29 , 30 , 31 ], various types of clay minerals [ 32 , 33 ], chitin and chitosan [ 34 , 35 , 36 ], zeolites [ 37 ], graphene oxide [ 38 , 39 , 40 ], amino-functionalized silica [ 41 ], amino-functionalized magnetic polymers [ 42 ] and metal–organic frameworks (MOFs) [ 43 , 44 , 45 , 46 ]. Among these adsorption materials, MOFs are a novel class of crystalline porous material with periodic network structure formed by the interconnection of inorganic metal centers (metal ions or metal clusters) and bridging organic ligands through self-assembly [ 43 , 44 , 45 ]. As novel organic–inorganic hybrid materials, MOFs are different from inorganic porous materials and general organic complexes.…”