Highly crystalline ionic covalent organic framework membrane for nanofiltration and charge-controlled organic pollutants removal

Chen, Tongfan; Li, Bin; Huang, Wenbo; Lin, Chunhui; Li, Guangshe; Ren, Hao; Wu, Yue; Chen, Shuhui; Zhang, Wenxiang; Ma, Heping

doi:10.1016/j.seppur.2020.117787

Cited by 53 publications

(31 citation statements)

References 56 publications

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“…The resultant membrane displayed the desired dye rejection (>90%) along with ultrahigh water permeance, which should be attributed to the electrostatic interaction between membrane materials and charged dyes. [47] In addition, Zhao and coworkers utilized the electrostatic interaction of ionic COF nanosheets with opposite charges and different apertures to assemble ultrathin 2D COF membranes for gas separation. [48] The obtained membrane generated a narrow aperture via compact staggered stacking that was driven by strong electrostatic interaction (Figure 7b), endowing the COF membrane with considerable gas separation performance.…”

Section: Chargementioning

confidence: 99%

“…By using this approach, the anionic COF membrane with good rejection rates for cationic dyes and surfactants also was developed. [47] In addition, this approach also has been used to synthesize COF nanosheets for the further fabrication of ultrathin COF membranes via LBL stacking. [119,120] However, it should be noted that this approach usually needs to separately dissolve amine monomers and aldehyde monomers in water phase and organic phase (Figure 12b).…”

Section: Liquid-liquid Interfacementioning

confidence: 99%

“…[107] Later, some flexile COF films were prepared on an oil-water interface and then transferred onto various porous substrates to construct COFbased composite membranes. [33,47,121,122] In this case, the mediation agent (PTSA) was used to avoid the formation of amorphous products. The as-synthesized COF membrane with high crystallinity and high aspect ratio achieved good dyes rejection (>79%) and ultrahigh water and organic solvents permeance.…”

Section: Water Treatmentmentioning

confidence: 99%

“…[33] Using a similar IP strategy, Ma and coworker prepared anionic COF membranes for the effective removal of cationic dyes and surfactants. [47] However, the solubility of most of monomers in water is poor, which limits the scalability of the conventional IP strategy. To address this problem, several alternative protocols were successively developed.…”

Section: Water Treatmentmentioning

confidence: 99%

“…[202] Therefore, the contributions of adsorption, as compared with that of sieving (including size exclusion and electrostatic repulsion), should be strictly examined. In other words, some indispensable experiments, [47,90,101,103,104,126,127,[177][178][179][180]185,203] such as static adsorption and continuous long-term stability with large feed volumes, should be conducted to quantificationally calculate the adsorption capacity of COF membranes, which is beneficial to figure out that which one separation behavior (adsorption or sieving) plays a dominate role in the membrane separation process. In addition, the separation mechanism of COF membranes should be discreetly explored in the future.…”

Section: Water Treatmentmentioning

confidence: 99%

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Covalent Organic Framework Membranes for Efficient Chemicals Separation

et al. 2021

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Membrane-based separation is an emerging technology to separate different components. [1] Owing to not only the functions of separation, concentration, and purification, but also the properties of energy efficiency, environmental friendliness, high efficiency, simplicity, manufacturing scalability, small footprint, and ease of operation and control, this technology has been widely used in chemical industry, environmental protection, medicine, food, and desalination. [2,3] Membrane is regarded as a significant method to solve the far-reaching issues such as water shortages, environmental pollution, and energy crisis.Along with the rapid industrialization and sharp increase in population, the problems of water shortages, environmental pollution, and energy crisis become more and more severe and complex, leading to the higher technology requirement for membrane separation. Although the frequently used traditional polymer membrane featured with low cost, good mechanical strength, excellent flexibility, and ease of processing, the two key parameters of permeability and selectivity that are generally used to evaluate membrane separation performance are interinhibitive because of the well-known trade-off effect. [4] One of the main reasons for the trade-off effect is the wide distribution of pore size in polymeric membranes. Therefore, materials with uniform and well-ordered pores are considered as perfect candidates for fabricating highperformance separation membranes. Keeping this in perspective, many meaningful studies have been conducted for constructing homoporous membranes [5] with traditional polymers as starting materials. The obtained membranes have a pore size ranging from 5 to 50 nm and possess great potential for ultrafiltration (UF). [6] However, in some practical application systems such as gas separation, dyes removal, protein and drug recovery as well as desalination, the kinetic dimensions of components to be separated usually are less than 5 nm. Therefore, it is very important that a homoporous structure with a pore size of less than 5 nm is constructed to be used in membrane separation.Covalent organic frameworks (COFs) [7][8][9][10][11] are an emerging class of organic porous crystalline materials with pores that range from 0.5 to 5 nm, [12,13] which are entirely composed by light elements, such as C, H, O, N, B, and Si and are connected by strong covalent bonds. Owing to the unique nature of their well-ordered and tailorable pore channels, high and permanent porosity, excellent thermostability and chemical stability, and ease of functionalization, COF materials have been demonstrated promising potential in many applications, including separation, [14] catalysis, [15] sensor, [16] optoelectronics, [17] energy conversion, [18] and semiconductors, [19] among others. Particularly, these characteristics of COF materials perfectly meet the requirements for making advanced separation membrane. For example, the uniform aperture, high porosity, and excellent stability are beneficial

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Section: Chargementioning

confidence: 99%

Section: Liquid-liquid Interfacementioning

confidence: 99%

Section: Water Treatmentmentioning

confidence: 99%

Section: Water Treatmentmentioning

confidence: 99%

Section: Water Treatmentmentioning

confidence: 99%

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Covalent Organic Framework Membranes for Efficient Chemicals Separation

et al. 2021

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Ultrathin Covalent Organic Framework Anchored on Graphene for Enhanced Organic Pollutant Removal

Guggenberger

Han

et al. 2022

Angewandte Chemie

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Covalent organic frameworks (COFs) are of great potential as adsorbents owing to their tailorable functionalities, low density and high porosity. However, their intrinsically stacked two-dimensional (2D) structure limits the full use of their complete surface for sorption, especially the internal pores. The construction of ultrathin COFs could increase the exposure of active sites to the targeted molecules in a pollutant environment. Herein, an ultrathin COF with a uniform thickness of ca. 2 nm is prepared employing graphene as the surface template. The resulting hybrid aerogel with an ultralow density (7.1 mg cm À 3 ) exhibits the ability to remove organic dye molecules of different sizes with high efficiency. The three-dimensional (3D) macroporous structure and well-exposed adsorption sites permit rapid diffusion of solution and efficient adsorption of organic pollutants, thereby, greatly contributing to its enhanced uptake capacity. This work highlights the effect of COF layer thickness on adsorption performance.

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