Hypercrosslinked Polymers Research Articles

Hypercrosslinked polymer derived carbon@MIL-100 magnetic material for the enhanced extraction of diclofenac

Herein we report for the first time the preparation of a magnetic hybrid carbon@MOF material by combining hypercrosslinked polymer-derived carbon and MIL-100(Fe) MOF. FeCl3, used as catalyst for the synthesis of the benzene-based hypercrosslinked polymer by Friedel-Crafts reaction, was reused for the preparation of a magnetic carbon with a high amount of iron particles, which in turn acted as precursor for the in situ growth of MIL-100(Fe) MOF on the carbon. The effect of the ligand amount and the transformation time in the conversion process was studied by X-ray diffraction and N2 adsorption–desorption isotherms. The developed hybrid material (C-BHCP@MIL-100(Fe)) was evaluated for the extraction of the emerging pollutant diclofenac (DCF) in dispersive mode and the adsorbent was easily retrieved by using an external magnet. The adsorption of DCF by C-BHCP@MIL-100(Fe) fitted the pseudo-second order kinetic model and the Langmuir isothermal model, with a maximum adsorption capacity of 210 mg/g, which is higher than many of the values of DCF adsorption capacity reported in the literature for magnetic adsorbents. The good extraction performance could be attributed to the high surface area and mesoporosity of the obtained hybrid material along with the coexistence of multiple π-π interactions and H-bond interactions between the DCF and the adsorbent. In addition, excellent reusability with a variation of a 2.2 % for 5 consecutive DCF extraction cycles, was obtained, demonstrating the potential of the developed carbon@MOF hybrid material for the removal of DCF and other organic pollutants. The developed synthesis approach can be extended to the preparation of other hypercrosslinked polymer derived carbon@MOFs with great potential for environmental applications.

Cover Feature: Hydroxy‐Functionalized Hypercrosslinked Polymers (HCPs) as Dual Phase Radioactive Iodine Scavengers: Synergy of Porosity and Functionality (ChemPlusChem 11/2022)

The cover feature image illustrates a family of hydroxy-functionalized hypercrosslinked polymers (HCPs) toward efficient capture of radioactive iodine from both vapour and water phase. The polymeric scavengers were also utilized to establish the first case of functionality and porosity synergy in this kind of material for radioactive iodine removal; a key advancement from the energy-economy standpoint of real-time radioactive contaminant sequestration. More information can be found in the Research Article by Sujit K. Ghosh and co-workers.

Facile synthesis of hypercrosslinked polymer as high-efficiency adsorbent for the enrichment of nitroimidazoles from water, honey and chicken meat

Design and fabrication of functionalized hypercrosslinked polymers (HCPs) for enhancing their performance by using green renewable monomers has attracted considerable research interest. In this study, hydroxyl‑functional HCP (labeled as OHHCP) was prepared via the knitting method by applying natural naringenin as a monomer for the first time. Due to the good hydrophilicity and strong H-bonding ability, the OHHCP showed high extraction capacity for nitroimidazoles. Thus, it was successfully applied as a potent adsorbent for solid phase extraction of five nitroimidazoles in water, honey and chicken meat, followed by high-performance liquid chromatography-diode array detector analysis. At the optimized conditions, the limit of detections (S/N = 3) of the proposed method for water, honey and chicken samples were 0.02 - 0.06 ng mL−1, 0.5 - 1.0 ng g−1 and 0.8 - 1.0 ng g−1, respectively. The recoveries were 80.0 - 110%, and the relative standard deviations were below 10.0%. The OHHCP also displayed good application prospects for other organic compounds with H-bonding capability. This study highlights the facile preparation of OH-functionalized HCPs from renewable and natural resources as potent adsorbents for polar compounds.

Hypercrosslinked waste polymers as adsorbents for O2/N2 separation

Waste polymer materials offer a lot of promise for recycling or enhancement in terms of the environment. HCPs (hypercrosslinked polymers) are an excellent contender for recycling polymers in environmental applications. We employed waste-expanded polystyrene and waste polycarbonate as precursors to make HCPs adsorbents for O2/N2 adsorption. Characterization analysis were performed to determine the adsorbents' morphology and structure. The fine adsorbent was waste-expended polystyrene which had been synthesized at 45 °C for 12 h and had a surface area of 802.84 (m2/g), an average pore diameter of 2.86 nm, and a micropore volume of roughly 184.46 (cm3/g). The Sips isotherm and Elovich kinetic models provided the best agreement (R2 = 0.9994), according to experimental data. At 5 °C and 10 bar, the fine adsorbent had the highest O2 and N2 adsorption, with 12.78 and 7.67 (mmol/g), respectively. Eventually, the kinetic evidence demonstrated that the process physically occurred. Over nine cycles, the sorbent's ability for adsorption decreased by about 5%, indicating a high degree of reusability for air separation. The method described in this study can be considered a promising approach to air separation and purification by eco-friendly hypercrosslinked polymers.

Hydroxy-Functionalized Hypercrosslinked Polymers (HCPs) as Dual Phase Radioactive Iodine Scavengers: Synergy of Porosity and Functionality.

Large-scale nuclear power plant production of iodine radionuclides (129 I, 131 I) pose huge threat in the events of nuclear disaster. Effective removal of radioiodine from nuclear waste is one of the most critical challenge because of the drawbacks of state-of-the-art adsorbents such as high cost, low uptake capacity and non-recyclability. Herein, two hydroxy-functionalized (-OH) hypercrosslinked polymers (HCPs), namely HCP-91 and HCP-92, have been synthesized and employed towards capture of iodine. High chemical stability along with synergistic harmony of high porosity and functionality of these materials makes them suitable candidates for capture of iodine from both vapor phase and water medium. Moreover, both the HCPs showed superior iodine removal performance from water in terms of fast kinetics and high removal efficiency (2.9 g g-1 and 2.49 g g-1 for HCP-91 and HCP-92 respectively). The role of functionality (-OH groups) and porosity has been established with the help of HCP-91, HCP-92 and non-functionalized biphenyl HCP for the efficient capture of I3 - ions from water. In addition, both HCPs exhibited excellent selectivity and recyclability towards triiodide ions, rendering the potential of these materials towards real-time applications. Lastly, Density functional theoretical studies revealed key insights and corroborate well with the experimental findings.

Tuning the Surface Area and Pore Size of Pyrene–Biphenyl-Coupled Hypercross-linked Polymers to Capture Toxic Organic Pollutants

Tuning the Surface Area and Pore Size of Pyrene–Biphenyl-Coupled Hypercross-linked Polymers to Capture Toxic Organic Pollutants

Ionic-containing hyper-crosslinked polymer: A promising bifunctional material for CO2 capture and conversion

Hyper-crosslinked polymers (HCPs) are a category of porous materials with the high specific surface area, abundant pore canal, and tunable structure. A very challenging topic is to fabricate ion-pair active sites into the skeleton structure of HCPs, which can endow HCPs with specific CO2 separation and catalytic characters. In this work, a series of hyper-crosslinked polymers with the high specific surface area and tunable ion-pair active sites are fabricated by using a one-pot method with simultaneous quaternization and Friedel-Crafts reactions. These ion-pair-containing hyper-crosslinked polymers (IHCPs) are served as adsorbents for selective separation of CO2 from CH4 and N2. It is found that CO2 uptake of IHCP-2 reaches 2.87 mmol·g−1 at 273 K and 1 bar, which is higher than that of the same type of ionic polymers that have been reported in the literature. The high CO2 adsorption capacity is due to the abundant microporous and high specific surface area of as-prepared IHCPs. More importantly, these IHCPs can also be used as recyclable catalysts for cycloaddition of CO2 and epoxides under metal- and cocatalyst-free conditions, affording corresponding cyclic carbonates in excellent yields. The high catalytic activity is attributed to synergistic contributions of the hierarchical pores and nucleophilic ion pair’s structure. This research provides an alternative strategy for development of bifunctional function materials towards efficient CO2 capture and conversion.

Solution Processing of Cross-Linked Porous Organic Polymers

ConspectusPorous organic polymers (POPs), essentially including polymers with intrinsic microporosity (PIMs), conjugated microporous polymers (CMPs), covalent organic frameworks (COFs), hyper-cross-linked polymers (HCPs) and so on, have recently attracted broad interest in many application areas because of their structural diversity and functional tunability. However, except for linear PIMs that can dissolve in organic solvents for solution processing into membranes, most POPs are highly cross-linked (hereafter termed CPOPs) and are synthesized as insoluble and unprocessable powders, which prevent CPOPs in many applications. Developing methodologies for solution processing CPOPs to high-quality membranes, monoliths, and (aero)gels has been a major challenge in this field because of the following issues. First, the inherently cross-linked structures and the strong framework–framework interactions in CPOPs give rise to very weak solvation of the frameworks, leading to easy aggregation and precipitation in solutions. Next, to date, several methods for preparing CPOP membranes have been proposed, but their conditions vary with different systems, and there lacks a general strategy for membrane formation of most CPOPs (or at least CPOPs of the same category). Additionally, CPOP-based monoliths and (aero)gels are rarely reported, and it has been considered difficult to control the hierarchical porosity to form the monoliths and (aero)gels during the CPOP syntheses. Last, the effects of the forms of membranes/(aero)gels on the transport (electron, ion, and mass) properties have not been intensively investigated for the lack of suitable systems. Therefore, since it was first announced accompanied by the birth of CPOPs, research studies regarding solution-processed CPOPs have been underexplored for a long time without significant advances being achieved.To break the unprocessable shackles of CPOPs, our group started to make contributions to this field in 2018. We developed two general strategies, namely, “charge-induced dispersion (CID)” and “thermal hyper-cross-linking (THC)” strategies, to produce high-quality CPOP membranes and (aero)gels, respectively. For the CID strategy, we found that the introduction of plenty of charges to the frameworks of CPOPs substantially enhanced their interactions with polar solvents, rendering the transparent, stable, and solution-like CPOP sols which could be further processed into membranes. For the THC strategy, we intensively investigated the gelation mechanism and found that this system was synthetically controllable to produce CPOP (aero)gels and could serve as a platform for hybridization with many porous materials to achieve a molecular-level entanglement. Moreover, we successfully demonstrated that the transport properties in the CPOP membranes and gels were largely promoted by 1–2 orders of magnitude compared to their powder forms, thereby expanding the use of CPOP membranes and gels in the fields of electronic conduction, proton conduction, iodine adsorption, and molecular separation with superior performance. In this Account, we summarize our above contributions, including (i) three detailed methods in CID strategy to produce CPOP membranes, (ii) THC strategy and the gelation mechanism, and (iii) transport properties in CPOP membranes/gels and the structure–function relationship. Overall, our studies not only provide an unprecedented paradigm of solution processing of previously unprocessable materials but also broaden the opportunities for future applications for CPOPs.

Amide-functionalized organic cationic polymers toward enhanced catalytic performance for conversion of CO2 into cyclic carbonates

Developing highly efficient, cost-effective and robust heterogeneous catalysts for carbon dioxide (CO2) fixation into valuable chemicals plays an essential role in carbon emissions reduction. Herein, a family of novel and bifunctional hypercrosslinked polymers, which consist of amide groups (-CONH-) as hydrogen bond donors (HBDs) and Br¯ as nucleophiles, were developed for metal- and co-catalyst free cycloaddition of CO2 to epoxides. The incorporation of amide units into the polymeric networks not only provided active sites for synergistic activation of epoxides, but it also enhanced their swelling abilities toward epoxide substrates. As a result, the optimal catalyst exhibited high catalytic performance towards the cycloaddition of CO2 and epoxide to cyclic carbonate, the catalytic activity was comparable to those of the homogeneous analogues and outperformed most of the metal-free polymeric catalysts previously reported. Experimental and density functional theory (DFT) investigations suggested that excellent activity of the catalyst stemmed from the synergistic effect between amide HBDs and Br¯ nucleophiles, as well as its excellent swelling ability toward epoxides. Additionally, the catalyst exhibited excellent structural stability and could be reused at least 10 times without significant activity loss. The present work not only highlights a versatile HBD to construct efficient and robust solid catalysts for CO2 fixation, but also paves the way to boost the performance of polymeric catalysts by engineering their swelling abilities toward reactant molecules.

Construction of hyper-crosslinked ionic polymers with high surface areas for effective CO2 capture and conversion

The design and preparation of ionic liquids functionalized polymer materials is a trending topic in the fields of polymer science for CO2 capture and utilization. In this work, a series of porous hyper-crosslinked ionic polymers (PIPs) with high surface area and abundant catalytic central units have been synthesized by a simple post-crosslinking of ionic liquid monomer and 4,4′-bis(chloromethyl)-1,1′-biphenyl. The prepared PIPs were used for CO2 adsorption, and their adsorption capacity for CO2 exceeded 100 mg g−1 at 273 K and 1.0 bar. Furthermore, the isotherm adsorption data of CO2 were fitted respectively by Langmuir, Freundlich, Redlich-Peterson, and Toth isotherm models to calculate the thermodynamic parameters, including changes in Gibbs free energy (ΔG°), enthalpy (ΔH°), entropy (ΔS°), and isosteric heat of adsorption (ΔHIsosteric). It is concluded that the adsorption process of CO2 on PIP is a spontaneous physical process. These PIP can also be used as heterogeneous catalysts for the cycloaddition of CO2 with epoxides under metal/solvent/cocatalyst-free conditions. The excellent yields (up to 99%) of cyclic carbonates are ascribable to synergistic contributions of abundant microporous and active ionic catalytic centers. This study provides a new idea for developing functionalized ionic polymers that combine capture and conversion of CO2.

Adsorption of Hydrophobic Ions on Environmentally Relevant Sorbents.

Environmental monitoring and remediation often requires the collection of harmful substances from aqueous solutions. Absorption with solids is a useful technique for binding such substances even at very low concentration levels. Many of these contaminants are weak acids or bases. Some novel, nonionic polymeric sorbents, such as hypercrosslinked polymers or polymers with balanced hydrophilic-lipophilic properties (HLB) have been found to bind weak acids and bases with high distribution coefficients even at pH values where these compounds are almost completely ionized (typically near pH 7). To understand this phenomenon and its practical consequences, we have experimentally studied the adsorption of ionizable weak acids and bases as a function of pH and ionic strength on a the OASIS® HLB sorbent. Not surprisingly, the ionic forms of the weak acids and bases were found to be much less bound in the aqueous solution than their neutral forms. In spite of this, OASIS® HLB binds weak acids and bases around pH 7 considerably better than typical hydrophobic sorbents. The high overall distribution coefficients around pH 7 could be explained by two factors. One is that on OASIS® HLB, and on some other novel polymeric sorbents, the binding constant of the moderately hydrophobic neutral form is on the order of 100,000, i.e., much higher than on typical hydrophobic sorbents. Thus, even if the proportion of the neutral form in solution is only around 1% near pH 7, the adsorption of the neutral form is still significant. On the other hand, the binding of the apparently hydrophilic ionized forms occurs with distribution coefficients well above 100. The distribution coefficient of the ionic form appears to depend on ionic strength and the presence of competing ions. Adsorption of the ionic forms is found to be very similar to the adsorption of ionic surfactants. The pH dependence of the total adsorption of neutral and ionic forms together, is found to be steep around pH 7, and therefore the varying pH of natural waters may strongly influence the binding efficiency in practical applications, such as the collection (concentration) of contaminants or their passive sampling.

Enhanced cello-oligosaccharides production from cellulose hydrolysis in molten salt hydrate over lignin-based hyper-cross-linked polymer (LHCP) adsorption

Selective hydrolysis of crystalline cellulose to cello-oligosaccharides in molten salt hydrates (MSHs) is a promising method for valorization of lignocellulose. However, the by-products derived from cellulose hydrolysis can facilitate cello-oligosaccharide degradation and decrease its selectivity. To address this issue, lignin-based hyper cross-linked polymers (LHCPs) were prepared to in situ adsorb by-products during hydrolysis and thus prevent cello-oligosaccharides from degradation. The synthesized LHCP‐33%, with a high lignin content of 33%, showed a remarkable surface area of 708.7 m2 g−1 and good hydrophilicity, exhibiting a promising adsorption capacity of 340 mg g−1 towards 5-hydroxymethylfurfural (5-HMF), which is supposed to be the major cellulose-derived by-product. We showed that 5-HMF adsorption was driven by the formation of CH-π bonds between 5-HMF and aromatic rings on LHCP. When LHCP‐33% was employed in cellulose hydrolysis, the yield of cello-oligosaccharide can be efficiently enhanced from 39.5% to 78.2%. This work offered a new application of lignin in enhanced cello-oligosaccharide production from cellulose.

Synthesis and characterization of waste Styrofoam hypercrosslinked polymer as an adsorbent for CO2 capture

AbstractIn this work, we used waste Styrofoam as a precursor to synthesize a hypercrosslinked polymeric (HCP) adsorbent for CO2 adsorption utilizing the Friedel–Craft procedure. The hypercrosslinked adsorbent was designed using formaldehyde dimethyl acetal (FDA) as the crosslinker. The precursor to crosslinker to catalyst ratio was 1:3:3, and the HCP synthesis was carried out for 12 h at 312.6 K. Fourier‐transform infrared spectroscopy, field emission scanning electron microscopy, and thermogravimetric analysis were used to analyze the waste Styrofoam hypercrosslinked (WSHC) adsorbent. The adsorbent attained an 802.84 m2/g Brunauer–Emmett–Teller (BET) surface area and an average pore diameter of 2.869 m3/g. The CO2 adsorption process was studied under different operating conditions, temperature between 298 and 328 K and pressure between 2 and 10 bar. WSHC adsorbent has the maximum CO2 uptake with a value of 11.053 mmol/g at 298 K and 10 bar. The behavior of the adsorption process was investigated using isotherm, kinetic, and thermodynamic models. Experimental findings indicated that the Sips isotherm and the second‐order kinetic models provided the best fit. The isotherm data indicated that adsorption occurs in multi‐layers and is heterogeneous. According to the thermodynamic characteristics, the process is exothermic and spontaneous. Finally, the kinetic findings established that the process happened physically. Additionally, a regeneration study after seven cycles revealed a 96.1% success rate. The current research may attempt to use waste Styrofoam as a gas separation adsorbent in the industry.

Hyper-crosslinked dicationic ionic liquid porous polymers for nitrophenol adsorption

In this work, an imidazolyl dicationic ionic liquid was employed as a monomer to construct a novel nitrogen-rich hyper-crosslinked polymer (HCP–N) for the separation of 4-nitrophenol (4-NP) from wastewater. HCP-N was fabricated through a facile one-pot Friedel-Crafts polymerization, using p-dichloroxylene as cross-linking agents, as well as pore structure regulators. The synthesized HCP-N were randomly stacked by lamellar blocks aggregated by nanospheres. The adsorption kinetic data complied well with pseudo-second-order rate equation while the adsorption isothermal equilibriums conformed to the Freundlich model. At the initial concentration of 1000 mg L−1, the adsorption capacity for 4-NP was up to 437 mg g−1. The influence of acidity, temperature and coexisted metal ions were investigated systematically. Coexisted Pb2+ at low concentration (<150 mg L−1) could significantly increase the adsorption capacity of HCP-N through complexing-bridging mechanism. The mechanism analyses revealed that hydrogen bonding, electrostatic and π−π interaction contributed together to the adsorption of 4-NP on HCP-N. The adsorbent could be recycled at least five times after the adsorbed 4-NP was separated by ethyl acetate extraction.

Sensitive determination of auxins in environmental water and peach beverage by hyper crosslinked polymer-based solid-phase extraction with high performance liquid chromatography-fluorescence detection

As plant regulators, auxins can promote plant growth. However, they have toxicity and may cause harm to humans. Due to their low concentrations in food sample matrices, the enrichment and analysis of trace auxins in food samples is a challenging work. In this work, a series of hyper crosslinked polymers (HCPs) were synthesized by Friedel-Crafts acylation to extract four auxins (indole-3-acetic acid, indole-3-propionic acid, indole-3-butyric acid and 1-naphthylacetic acid). Among these HCPs, the QP-TC-HCP, synthesized from p-quaterphenyl (QP) and terephthaloyl chloride (TC), showed the best adsorption performance for the auxins. It was then applied as the adsorbent for the solid-phase extraction of the auxins from environmental water and peach beverage samples, followed by high performance liquid chromatography-fluorescence detection. Under the optimized conditions, the limits of detection were 3.0–12.0 pg mL–1 for environmental water and 18.0–36.0 pg mL–1 for peach beverage sample. The method recoveries of the auxins for the spiked samples were in the range of 85.0–110.0%. The established method provided an alternative approach for the determination of auxins in food samples. In addition, different types of organic compounds were tested for the extraction by the QP-TC-HCP to assess its application potential and adsorption mechanism. It was concluded that the QP-TC-HCP had better extraction performance for the compounds with certain hydrophilicity and more hydrogen bonding sites.

Facile fabrication of hydroxyl-functionalized hypercrosslinked polymer for sensitive determination of chlorophenols

Three hydroxyl-functionalized hypercrosslinked polymers (HCP-POL, HCP-HQ and HCP-PG) were synthesized by Friedel-Crafts reaction. The HCP-HQ displayed the largest surface area and highest adsorption capacity for chlorophenols (CPs). Thus, the HCP-HQ was further modified with magnetism to obtain M-HCP-HQ. An efficient magnetic solid-phase extraction method with M-HCP-HQ as adsorbent was developed for the first time to simultaneously extract four CPs from water and honey samples before analysis by high performance liquid chromatography-diode array detection. Under optimized conditions, the low detection limits (S/N = 3) were obtained to be 0.06–0.10 ng mL−1 for water and 0.80–1.75 ng g−1 for honey. The method recovery was 80.7%–119%, with relative standard deviations below 9.5%. The enrichment factors of the CPs were in the range of 57–220. The extraction mechanism could be attributed to the strong polar interaction, hydrogen bonding and π-π interactions between the M-HCP-HQ and CPs. The M-HCP-HQ based method can be served as a reliable and sensitive tool for detection CPs in water and honey samples.

Highly efficient removal of uranium from aqueous solution by a novel robust phosphonic acid functionalized aromatic-based hyper-crosslinked porous polymer

Highly efficient removal of uranium from aqueous solution by a novel robust phosphonic acid functionalized aromatic-based hyper-crosslinked porous polymer

Synthesis of nitrogen-rich magnetic hypercrosslinked polymer as robust adsorbent for the detection of neonicotinoids in honey, tomatoes, lettuce and Chinese cabbage

In this study, a novel nitrogen-rich magnetic hypercrosslinked polymer (Fe3O4@Ph-HCP) was fabricated via a facile one-pot reaction of 1,3,5-triphenylbenzene, 2,4-dichloropyrimidine and phenyl-functionalized magnetic Fe3O4 nanoparticles. The Fe3O4@Ph-HCP possessed high specific surface, abundant nanopores and good stability. Especially, Fe3O4@Ph-HCP exhibited excellent adsorption capability with fast adsorption rate to neonicotinoid insecticides. It was applied as a superior magnetic adsorbent for rapid enrichment and isolation of four neonicotinoid insecticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) from honey, tomato, lettuce and Chinese cabbage samples prior to high performance liquid chromatography-diode array detection. Under the optimized conditions, the good linearity was obtained in the range of 1–1000 ng g−1 for honey, tomato, lettuce and Chinese cabbage samples, and the detection limits (S/N = 3) were 0.30–0.67 ng g−1 for honey, 1–1.5 ng g−1 for tomato, lettuce and Chinese cabbage. The spiked recoveries were 80.1–111%, and relative standard deviations were less than 10.0%. These results demonstrate that the developed method can be used as a good alternative method for sensitive determination of neonicotinoid insecticides in complex samples.

Fe-Immobilised Catechol-Based Hypercrosslinked Polymer as Heterogeneous Fenton Catalyst for Degradation of Methylene Blue in Water.

Clean water is one of the sustainable development goals. Organic dye is one of the water pollutants affecting water quality. Hence, the conversion of dyes to safer species is crucial for water treatment. The Fenton reaction using Fe as a catalyst is a promising process. However, homogeneous catalysts are normally sensitive, difficult to separate, and burdensome to reuse. Therefore, a catechol-based hypercrosslinked polymer (catechol-HCP) was developed as an inexpensive solid support for Fe (catechol-HCP-Fe) and applied as a heterogenous Fenton catalyst. The good interaction of the catechol moiety with Fe, as well as the porous structure, simple preparation, low cost, and high stability of catechol-HCP, make it beneficial for Fe-loading in the polymer and Fenton reaction utilisation. The catechol-HCP-Fe demonstrated good catalytic activity for methylene blue (MB) degradation in a neutral pH. Complete decolouration of 100 ppm MB could be observed within 25 min. The rate of reaction was influenced by H2O2 concentration, polymer dose, MB concentration, pH, and temperature. The catechol-HCP-Fe could be reused for at least four cycles. The dominant reactive species of the reaction was considered to be singlet oxygen (1O2), and the plausible mechanism of the reaction was proposed.

Processable amidoxime functionalized porous hyper-crosslinked polymer with highly efficient regeneration for uranium extraction

Uranium is not only toxic and radioactive, even more an important resource to ensure the nuclear energy development. This work reported an amidoxime-based hyper-crosslinked polymeric resin adsorbent (HWB-AO) to extract uranium from ocean. The monolithic matrix was prepared by suspension polymerization using styrene (St) and divinylbenzene (DVB), followed by post-polymerization modification to graft diaminomaleonitrile (DAMN) and conduct amidoximation to introduce amidoxime groups (AO) in its interior and surface. AO can enhance the affinity to uranium and hydrophilicity to accelerate the uranium adsorption. The monolithic structure overcome the problem that powder adsorbent is easy to drain in real seawater, so the monolithic is easier to apply. The batch adsorption experiments results showed that HWB-AO has an magnificent uranium removal rate (85%) and the maximum adsorption capacity (qe,max) is 256.4 mg g−1. In addition, HWB-AO still maintains a giant adsorption efficiency after eight times adsorption–desorption cycles and is environmentally friendly. Concurrently, HWB-AO exhibits excellent selectivity and removal rate (greater than88%) in modified seawater. Therefore, HWB-AO is considered as a potential adsorbent to perform uranium extraction from natural seawater.