Covalent organic frameworks (COFs) are an emerging class of highly porous crystalline organic polymers comprised entirely of organic linkers connected by strong covalent bonds. Due to their excellent physicochemical properties (e.g., ordered structure, porosity, and stability), COFs are considered ideal materials for developing state-of-the-art separation membranes. In fact, significant advances have been made in the last six years regarding the fabrication and functionalization of COF membranes. In particular, COFs have been utilized to obtain thin-film, composite, and mixed matrix membranes that could achieve effective rejection (mostly above 80%) of organic dyes and model organic foulants (e.g., humic acid). COF-based membranes, especially those prepared by embedding into polyamide thin-films, obtained adequate rejection of salts in desalination applications. However, the claims of ordered structure and separation mechanisms remain unclear and debatable. In this perspective, we analyze critically the design and exploitation of COFs for membrane fabrication and their performance in water treatment applications. In addition, technological challenges associated with COF properties, fabrication methods, and treatment efficacy are highlighted to redirect future research efforts in realizing highly selective separation membranes for scale-up and industrial applications.
Ionic Covalent Organic Framework-Based Membranes for Selective and Highly Permeable Molecular Sieving
Xin Liu, Jinrong Wang, Yuxuan Shang, Cafer T Yavuz, Niveen M Khashab
Two-dimensional covalent organic frameworks (COFs) with uniform pores and large surface areas are ideal candidates for constructing advanced molecular sieving membranes. However, a fabrication strategy to synthesize a free-standing COF membrane with a high permselectivity has not been fully explored yet. Herein, we prepared a free-standing TpPa-SO3H COF membrane with vertically aligned one-dimensional nanochannels. The introduction of the sulfonic acid groups on the COF membrane provides abundant negative charge sites in its pore wall, which achieve a high water flux and an excellent sieving performance toward water-soluble drugs and dyes with different charges and sizes. Furthermore, the COF membrane exhibited long-term stability, fouling resistance, and recyclability in rejection performance. We envisage that this work provides new insights into the effect of ionic ligands on the design of a broad range of COF membranes for advanced separation applications.
Boronization of Nickel Foam for Sustainable Electrochemical Reduction of Nitrate to Ammonia
Zhong-Hua Xue, Han-Cheng Shen, Peirong Chen, Guang-Xue Pan, Wei-Wei Zhang, Wei-Meng Zhang, Shi-Nan Zhang, Xin-Hao Li, Cafer T Yavuz
Electrochemical reduction of aqueous nitrates has emerged as a sustainable and practical approach in combining water treatment and ammonia fertilizer synthesis. However, the development of highly integrated catalytic electrodes with consistently high activity from non-noble metals remains a challenging issue despite the potential to greatly decrease costs and promote real-world applications. Here, we report a high-performance electrode with electron-abundant surfaces obtained from direct boronization of nickel foam, rendering a stable ammonia yield rate of 19.2 mg h–1 cm–2 with high Faradaic efficiency of 94% for NO3–-to-NH3 conversion. The microprocessing lowers the work function and initiates a local electric field for the nickel foam by converting acid-stable surface nickel oxides into dyadic nanosheets composed of metallic nickel and amorphous nickel borates, thus promoting the adsorption and transformation of nitrate anions. Furthermore, the spent electrode enables a rapid and effective regeneration by undergoing another round of boronization, which ensures a long lifetime for the practical application of our electrode design.
nnentitelbild: Covalent Scrambling in Porous Polyarylthioethers through a Stepwise SNAr for Tunable Bandgap and Porosity
Doyun Kim, Thien S Nguyen, Hyejeong Lee, Bolormaa Bayarkhuu, Vepa Rozyyev, Jeehye Byun, Sheng Li, Cafer T Yavuz
A polycondensation reaction constitutes the simplest route to generating porous poly(aryl thioether)s. Through a multi-para-nucleophilic substitution of perfluoroaromatic compounds with sodium sulfide, temperature-dependent formation of thioether linkages leads to stepwise transition of the polymers into network structures with controllable porosity and bandgap, as reported by Jeehye Byun, Sheng Li, Cafer T. Yavuz, and co-workers in their Research Article (e202304378).
Synthesis of stable single-crystalline carbon dioxide clathrate powder by pressure swing crystallization
Zhiling Xiang, Congyan Liu, Chunhui Chen, Xin Xiao, Thien S Nguyen, Cafer T Yavuz, Qiang Xu, Bo Liu
Reversible CO2 capture and release under ambient conditions is
crucial for energy-efficient carbon capture and storage. Here, we
report the pressure swing crystallization of CO2 in a single-crystalline guanidinium sulfate-based clathrate salt under practical conditions of 52 kPa and 298 K, with a high CO2 density (0.252 g cm3
)
and capacity (17 wt %). The captured CO2 is released as a pure
stream through moderate means of pressure or temperature stimulation, all while the desorbed Gua2SO4 is ready for another cycle.
The clathrate is selective exclusively to CO2 even in the presence
of common flue gas components, such as water vapor and N2, owing
to the specific electrostatic interaction between the CO2 and guanidinium cations. The mechanism unraveled through single-crystal
studies is distinctively different from physisorption or chemisorption, opening up a promising venue for future carbon capture and
storage technologies through rapid CO2 solidification using an
abundant salt.
Catalytic ammonia decomposition enables ammonia to be a hydrogen gas carrier for a carbon-free fuel economy. The challenge is to obtain high conversion yields and rates at low temperatures for a prolonged time. A promising approach is to engineer a catalyst support to minimize deleterious effects like sintering. Here, we compared a conventional 2D planar porous framework support with a vertically standing 2D structure to ascertain the effects of support geometry on the catalytic performance. The catalysts were made by loading ruthenium (Ru) nanoparticles onto the structures, and the catalytic activities were monitored by varying the ammonia (NH3) feeding rate and reaction temperature. Unlike the planar version, the vertically standing 2D support prevented nanoparticle aggregation, retained the original nanoparticle size, and showed an excellent hydrogen production rate (95.17 mmol gRu−1 min−1) at a high flow rate of 32,000 mL gcat−1 h−1 at a temperature of 450 °C.
Barium Hexaferrite Nanofiber Filter and Method for Removing Heavy Metals and Separating Magnetic Nano Particles Using the Same
KR 10-1433332，Aug 18, 2014.
C. T. Yavuz, H. A. Patel, J. Byun
The present invention relates to a barium hexaferrite nanofiber filter and a method for removing heavy metals using the same and, more specifically, to a method for separating, from aqueous media, magnetite having arsenic adsorbed thereto using barium hexaferrite nanofiber which shows the highest level of saturable magnetism of nanofibers. The barium hexaferrite nanofiber according to the present invention can separate magnetite particles completely from aqueous media owing to high magnetism, and can have high possibility of commercialization as the barium hexaferrite nanofiber can be woven in the shape of a filter and a continuous process method can be introduced. In addition, the barium hexaferrite nanofiber can be used practically in a water treatment site and thus can be supplied at low costs to some developing countries that have serious arsenic intoxication problems, as the barium hexaferrite nanofiber is easy to synthesize, and material costs and production costs are very low.
Amidoxime-Polymers of Intrinsic Microporosity (PIMs) and Method for Preparing the Same
KR 10-1429154，Aug 5, 2014.
C. T. Yavuz, H. A. Patel
More particularly, the present invention relates to an amidocyclic microporous polymer having excellent carbon dioxide adsorbing ability, a method for producing the same, and a method for adsorbing or collecting carbon dioxide using the amidinocarbon microporous polymer. will be.
According to the present invention, the amicocyclic microporous polymer has an increased specific surface area as compared with the microporous polymer and has an excellent carbon dioxide adsorbing ability, thereby reducing the amount of carbon dioxide contained in the exhaust gas.
Azo Bridged Porous Covalent Organic Polymers and Method for Preparing the Same
KR 10-1453390，Oct 15, 2014.
C. T. Yavuz, H. A. Patel, A. Coskun, S. Je
More particularly, the present invention relates to a porous organic polymer covalently bonded to an Azo group having excellent carbon dioxide adsorbing ability, a method for producing the porous organic polymer, and a method for collecting carbon dioxide using the porous organic polymer .
According to the present invention, a porous organic polymer covalently bonded to an azo group has high stability against high temperature and water, and has excellent carbon dioxide adsorbing ability, so that it can be used as a main raw material of a next-generation gas storage material, thereby reducing the amount of carbon dioxide in the air .
Covalent Organic Polymers with Tröger’s Base Functionalities and Adsorbent of Carbon Dioxide Comprising the Same
KR 10-1546888，Aug 18, 2015.
C. T. Yavuz, J. Byun, H. A. Patel, A. Coskun, S. Je,
The present invention provides a curability-based organic curability organic polymer and a carbon dioxide adsorbent containing the same. The curability of the curability of the curability of the curability of the curability of the three- Based covalently bonded organic polymers and carbon dioxide adsorbents containing them.
Two dimensional Porous Benzoxazole linked Covalent Organic Polymers and Use Thereof
KR 10-1604104，Mar 10, 2016.
C. T. Yavuz, D. Ko, H. A. Patel
The present invention relates to a two-dimensional porous organic polymer linked by benzoxazole, and a use thereof. More particularly, the present invention relates to a method for producing a porous organic polymer having a structure of 4-6-diaminoresorcinol dihydrochloride, 3.3'-dihydroxybenzidine or 2,2-bis - (3-amino-4-hydroxyphenyl) hexafluoropropane with tert-butyldimethylsilyl chloride is reacted with 1,3,5-benzenetricarbonyl trichloride to obtain a benzoxazole derivative To a two-dimensional porous organic polymer and a use thereof.
The two-dimensional porous organic polymer linked with benzoxazole according to the present invention is excellent in heat and moisture stability, and has high selectivity for carbon dioxide, which is useful for efficient adsorption of carbon dioxide in various environments.
Disulfide-linked Covalent Organic Polymers and Method for Preparing the Same
KR 10-1644542， July 26, 2016.
C. T. Yavuz, H. A. Patel
More particularly, the present invention relates to a disulfide-based covalent organic polymer prepared using a thiol-ene reaction; A manufacturing method thereof; And the use of the organic solvent absorbent of the organic polymer. The produced disulfide-based organic polymer can be used as an absorbent capable of selectively absorbing various organic solvents in an aqueous solution or wastewater.
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