Amidoxime Functional Groups Research Articles

Amidoximated Bacterial Cellulose Film for Pb2+ Adsorption in Aqueous Environment

Abstract This study investigated the application of amidoximated bacterial cellulose (AMO-BC) film for lead (Pb) adsorption from aqueous solutions. In our previous study, bacterial cellulose has been successfully modified through amidoximation to enhance its metal adsorption capacity. In order to modify the bacterial cellulose (BC) film, acrylonitrile was grafted onto it initiated by an electron beam to create BC-grafted-polyacrylonitrile (BC-g-PAN). After that, amidoximated bacterial cellulose (AMO-BC) was generated when BC-g-PAN reacted with hydroxylamine hydrochloride to add amidoxime functional groups to the cellulose backbone. Then, AMO-BC before and after lead adsorption was characterized using Fourier-transform infrared spectroscopy (FTIR). The adsorption capacity of AMO-BC for lead ions was evaluated through batch adsorption experiments with the initial lead concentration of 200 mgL−1 and an adsorbent dose of 20 mg, on pH 6 for two hours of the adsorption process. The results showed that AMO-BC exhibited higher lead adsorption capacity than pristine bacterial cellulose i.e., 44.56 and 50.96 mg/gram for BC and AMO-BC films, respectively.

Synthesis of bifunctional copolymeric nanofibers with selective extracting U(VI) from the solution and antibacterial property

Facing the problem of future nuclear fuel shortage, developing high-performance adsorbent materials is key. In this work, the amidoxime group/imidazole functionalized ionic liquid copolymer fibers containing bromide salts, and fluoroborate salts (namely P(AO/VEIMBr)8 and P(AO/VEIMBF4)6) were prepared by a one-pot method and free radical polymerization, hydroxyl amination reaction and electrostatic spinning, and characterized by SEM, FT-IR, and 1 H NMR. The influence of solid-liquid ratio, ionic strength, and adsorption time on the adsorption performance was investigated by batch adsorption experiments. In the meanwhile, the adsorption kinetics and thermodynamic processes of U(VI) on the copolymer fibers was also studied. Adsorption mechanism of U (VI) on polymer fibers was explored by XPS spectroscopic analysis combined with DFT method. Finally, the antimicrobial properties of the copolymer fibers were tested. The experimental results showed that the polymer nanofibers synthesized for U(VI) has a fast adsorption, high adsorption capacity at ionic strength close to seawater, and excellent reusability. The adsorption process conformed to the pseudo-second-order kinetic model and Langmuir model, which indicated that chemical adsorption and monolayer adsorption are dominant for adsorption U(VI) on the polymer nanofibers, and exhibits the highest Uranium adsorption capacity (76.92 mg/g and 81.96 mg/g at pH=8.1+0.1, respectively). XPS result showed the amine nitrogen and oxime oxygen in the amidoxime functional group were coordinated with uranyl(VI) ions. The antibacterial experiments showed that the copolymer fibers have antimicrobial properties and the antibacterial rate is over 90 %. Therefore, the nanofibers may be a promising material for extracting uranium from the weak alkaline wastewater or seawater.

Constructing molecular sieve-based MOFs nanofiber composites for separating Co(II) from wastewater

In addressing the crucial need for separating cobalt ions from leachate solutions of spent ternary lithium batteries (TLBs), this study focuses on the development of an innovative molecular sieve (MS)-based MOFs material, MS-MIL-53(Al), synthesized by combining MS with 2,5-dihydroxyterephthalic acid. Since the powdered MS-MIL-53(Al) material presents a granular powdery form, which is difficult to recover during the adsorption process, electrospun nanofibers denoted as MS-MIL-53(Al)/PAN, were fabricated and functionalized with hydroxylamine hydrochloride to create MS-MIL-53(Al)/AOPAN. Static adsorption experiments conducted with MS-MIL-53(AL)/AOPAN as the adsorbent in cobalt-containing wastewater revealed a maximum adsorption content of 65.3 mg/g for Co(II). Moreover, the material exhibited a tensile strength at the breaking point of 0.077 kPa, indicating its excellent mechanical properties. The adsorption process followed pseudo-second-order kinetics and the Langmuir isotherm model, showcasing a spontaneous, endothermic monolayer chemical adsorption behavior. XPS analysis highlighted the influence of hydroxy and amidoxime functional groups on Co(II) adsorption. Notably, MS-MIL-53(Al)/AOPAN displayed exceptional stability, retaining over 90 % of its adsorption capacity after five cycles, demonstrating its potential for efficient Co(II) separation in wastewater treatment. This study is the first to synthesize MOFs material using MS as the base material, showing potential cost reduction and enhanced adsorption capabilities, with implications for advancing the innovative use of MOFs.

Experimental and theoretical investigations on Hg(II) removal by recyclable composite sorbents comprised of polymers bearing thiourea or amidoxime functional groups and mesoporous silica

It is extremely desirable but still challenging to skilfully manufacture highly efficient sorbents to remmediate, in a reversible manner, the water pollution with mercury. Herein, new sorbents for Hg(II) ions have been designed by the initial synthesis of polyacrylonitrile networks inside mesoporous SiO2 microparticles, followed by the chemical modification of acrylonitrile groups with thiourea or amidoxime moieties. The Hg(II) ions sorption properties of the new composites were compared with respect of initial solution pH, contact time, equilibrium concentration and impact of interfering metal ions. It was demonstrated that the sorbents containing thiourea groups exhibited superior sorption capacities (1.76 mmol Hg(II) g−1) compared to the ones containing amidoxime groups (1.68 mmol Hg(II) g−1), and also higher selectivity for Hg(II) ions separation from binary mixtures with Cu(II), Cd(II) or Pb(II) ions. Kinetic study and DFT results supported a combined sorption mechanism, both physical sorption and chem-isorption being possible. Following the elution of Hg(II) ions with 1 M HNO3 and the regeneration with 0.1 M NaOH, all sorbents exhibited around 90 % sorption capacity recovery after 4 reuse cycles.

Mechanism for the seleikctive adsorption of uranium from seawater using carboxymethyl-enhanced polysaccharide-based amidoxime adsorbent

Land-based uranium resources are becoming scarce because of the widespread development and use of nuclear energy. Therefore, to make up for the shortage of uranium resources, a new chitosan/carboxymethyl-β-cyclodextrin/quaternary ammonium salt–functionalized amidoxime carbon adsorbent (CSAOCF) was designed and synthesized for extracting uranium from seawater. Experimental studies show that the adsorption of uranium by CSAOCF is a spontaneous endothermic reaction and chemical adsorption. The theoretical maximum adsorption capacity of uranium can reach 726 mg/g at 308 K and pH = 6. Moreover, the adsorption efficiency and selectivity of CSAOCF for uranium were significantly improved after the introduction of the carboxymethyl group, and the selection and partition coefficient of CSAOCF for uranium and vanadium increased from 16-fold to 30-fold under the same conditions. This indicates that there is a synergistic effect between carboxyl and amidoxime groups, which can promote the adsorption of uranium by CSAOCF. Furthermore, CSAOCF exhibits good oil resistance and can be reused more than five times. Therefore, CSAOCF containing carboxymethyl and amidoxime functional groups can considerably improve the selective adsorption of uranium and has great potential in the extraction of uranium from seawater.

Asymmetric Alternative Current Electrochemical Method Coupled with Amidoxime-Functionalized Carbon Felt Electrode for Fast and Efficient Removal of Hexavalent Chromium from Wastewater

A large amount of Cr (VI)-polluted wastewater produced in electroplating, dyeing and tanning industries seriously threatens water ecological security and human health. Due to the lack of high-performance electrodes and the coulomb repulsion between hexavalent chromium anion and cathode, the traditional DC-mediated electrochemical remediation technology possesses low Cr (VI) removal efficiency. Herein, by modifying commercial carbon felt (O-CF) with amidoxime groups, amidoxime-functionalized carbon felt electrodes (Ami-CF) with high adsorption affinity for Cr (VI) were prepared. Based on Ami-CF, an electrochemical flow-through system powered by asymmetric AC was constructed. The mechanism and influencing factors of efficient removal of Cr (VI) contaminated wastewater by an asymmetric AC electrochemical method coupling Ami-CF were studied. Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) characterization results showed that Ami-CF was successfully and uniformly loaded with amidoxime functional groups, and the adsorption capacity of Cr (VI) was more than 100 times higher than that of O-CF. In particular, the Coulomb repulsion effect and the side reaction of electrolytic water splitting were inhibited by the high-frequency anode and cathode switching (asymmetric AC), the mass transfer rate of Cr (VI) from electrode solution was increased, the reduction efficiency of Cr (VI) to Cr (III) was significantly promoted and a highly efficient removal of Cr (VI) was achieved. Under optimal operating conditions (positive bias 1 V, negative bias 2.5 V, duty ratio 20%, frequency 400 Hz, solution pH = 2), the asymmetric AC electrochemistry based on Ami-CF can achieve fast (30 s) and efficient removal (>99.11%) for 0.5-100 mg·L-1 Cr (VI) with a high flux of 300 L h-1 m-2. At the same time, the durability test verified the sustainability of the AC electrochemical method. For Cr (VI)-polluted wastewater with an initial concentration of 50 mg·L-1, the effluent concentration could still reach drinking water grade (<0.05 mg·L-1) after 10 cycling experiments. This study provides an innovative approach for the rapid, green and efficient removal of Cr (VI) containing wastewater at low and medium concentrations.

Addressing Short-Chain PFAS Contamination in Water with Nanofibrous Adsorbent/Filter Material from Electrospinning.

ConspectusPer- and polyfluoroalkyl substances (PFAS) stand for thousands of fully/highly fluorinated aliphatic chemicals, which have been widely manufactured and used in consumer products. Due to easy deprotonation of headgroups and high strength of C-F bonds in their molecules, PFAS are water-soluble and extremely stable in our environment. Significant accumulation of PFAS in water bodies started as early as the beginning of their production in the late 1940s. Recent studies confirmed the occurrence and accumulation of PFAS in all human tissues as well as their harmful health effects. Upon environmental regulations and health advisories, the PFAS industry quickly shifted to short-chain PFAS, e.g., hexafluoropropylene oxide dimer acid and its ammonium salt (GenX), to replace traditional long-chain PFAS. According to the recent fact sheet by the U.S. Environmental Protection Agency (EPA) in October 2021, however, GenX turned out to be more toxic than people originally thought and has shown health effects on liver, kidney, immune system, and so forth upon animal tests. On June 15, 2022, the EPA released the final health advisory for GenX, which is just 10 ppt. Thus, there is an urgent need of novel adsorbents for highly effective GenX remediation from water.Until now, there have been just a few reports on the remediation of GenX from water despite its popular use. In this Account, we reviewed current technology on PFAS remediation and illustrated our research on how to use polyacrylonitrile (PAN), a common and economic polymer for water filtration, in the form of nanofibrous membrane with handy chemical surface modification to develop innovative adsorbent/filter material for effective and scalable GenX remediation from water at the largest HBCU in the nation together with opportunities and challenges that are associated with this research. For the first time, we compared the GenX removal capability of electrospun PAN (ESPAN) nanofibrous membrane and amidoxime surface-functionalized ESPAN (ASFPAN) nanofibrous membrane. By modifying the surface of ESPAN nanofibrous membrane and introducing amidoxime functional group, the maximum GenX removal capacity (weight-normalized GenX removal) was almost doubled and reached ∼0.6 mmol/g at pH 4, which is higher than or comparable to that of most reported adsorbents for GenX removal. Hydrophobic interaction and dipole-dipole interaction could be the GenX adsorption mechanism on the ESPAN nanofibrous membrane while surface hydrophilicity and electrostatic interaction play major roles in GenX adsorption on the ASFPAN nanofibrous membrane. Our research shed light on understanding the GenX adsorption mechanism and developing new adsorbent/filter materials for practical short-chain PFAS remediation from water.

Biofouling-resistant polyamidoxime-based natural hierarchical porous bamboo strips prepared by in-situ polymerization for uranium extraction from seawater

Effectively extracting uranium (VI) [U(VI)] from seawater requires efficient adsorbents. Generally, there are two major factors that affect the adsorption efficiency of adsorbents, including the biofouling around the adsorbents and the relative density of adsorption active sites. To enhance the practical application value of powdered polyamidoxime-based materials, macro-braidable and hierarchical porous bamboo strips (BS) with antibacterial properties are selected to synthetize polyamidoximized bamboo strips (PAOBS) by in-situ polymerization methods. On the one hand, natural BS have a bamboo quinone structure, and their intrinsic structure is not destroyed during the reaction process, which endows PAOBS with excellent antibacterial properties. In addition, PAOBS retains the hierarchical porous structure of BS, providing channels for the adsorption process, which is beneficial to achieve the maximum utilization of adsorption active sites. On the other hand, PAOBS increases the relative density of amidoxime functional groups, and its adsorption capacity (233 mg g−1) is approximately 2.14 times higher than that of pure PAO at pH= 6.0, including electrostatic effect and chelation mechanism. After PAOBS is floated in the Yellow Sea Basin for 30 days, its adsorption capacity for U(VI) reaches 1.03 mg g−1. Importantly, the addition of BS increases the coordination modes with the uranyl ion, and the single coordination mode of CH(NH2)=N-OH from PAO is translated to the three mixed coordination modes of CH(NH2)=N-OH, CH(NH2)=N-OH, and CH(NH2)=N-OH and adjacent CH(NH2)=N-OH from PAOBS. Construction of PAOBS plays a role in the design of novel adsorbents with high relative density of adsorption active sites and biofouling-resistant, laying the steady foundation for further realizing sustainable U(VI) extraction from seawater.

Removal of Cu (II) Ions from Aqueous Solution Using Poly-Amidoxime Resin from Grafted Millet Husk Cellulose

Poly-amidoxime ligand was synthesized on the cellulose isolated from millet husk through a graft copolymerization process for adsorption of Cu (II) ion from aqueous solution. The functional group, thermal degradation and morphology of the adsorbent were investigated by Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM), respectively. The FTIR results showed that grafting was successful due to the presences of 2244 cm-1 for cyano group (CN) and also band at 1640 cm-1 and 1380 cm-1 that replaced 2244 cm-1 which successfully confirmed the synthesis of poly(amidoxime) functional group. The TGA showed two stages of thermal degradation 12 % weight loss observed in amidoxime at 240 0C which is due degradation of amidoxime functional group then it reduces to 2% in second stage at 530 0C which revealed the improved thermal stability of the material. The SEM image showed a clear morphology of the absorbent before adsorption and after adsorption. The Initial concentration, adsorbent dosage and contact time were taken as independent variables. The adsorption process was optimized by central composite design (CCD) in Response surface methodology (RSM). The predicted value is in good agreement with experimental value and also the ANOVA result showed that all the independent variables have significant impact with the adsorbent. The optimum condition achieved in the experiment was at initial concentration of 150 mg/L, adsorbent dosage of 0.3 g and contact time of 90 min for Cu2+ with percentage removal of 55.41 % predictably and 54.92 % experimentally.

Amidoximated CeMOFs superstructures with algae-removing properties for efficient uranium extraction from simulated seawater

Metal-organic frameworks have great potential in the field of uranium extraction from seawater due to their abundant functional groups. The binding energy of different types of functional groups differ significantly from uranium, which mainly affects the efficiency of uranium extraction. MOFs materials self-assembled with nanostructures have better structural stability and can graft functional groups efficiently. By introducing functional groups into the ligands and organic modification, we successfully grafted amino and amidoxime groups into Cerium Terephthalate (CeBDC). The result exhibits that the aminated CeBDC (CeBDC-NH2) and amidoximated CeBDC (CeBDC-AO) make great strides in the maximum adsorption capacity and distribution coefficient (Kd). Among them, CeBDC-AO exhibit high adsorption amount of 723.8 mg g−1 and the Kd reached approximately 3.2 × 106 mL·g−1. Meanwhile, this nano-superstructure also has excellent algae removal ability, and the algae removal ability reaches 1.04 × 107 cells/mg in a static state. According to the density functional theory (DFT) calculation, amidoxime functional groups have the best adsorption effect in terms of surface electrostatic force. More broadly, this work has designed a new type of nano superstructure MOFs with little pollution, high efficiency and high selectivity, which can provide a new idea for the future work of extracting uranium from seawater.

Single-molecule polyamidoxime adsorbent for highly efficient uranium recovery and removal

Inspired by single-atom catalysts (SACs), a “single-molecule” polyamidoxime (SM-PAO) adsorbent is designed to implement ultra-fast and “nothing left” enrichment of uranium in a water environment. The amphoteric property of SM-PAO is systematically characterized and discussed for the first time. The amidoxime functional groups are nearly 100% accessible due to the dissolution of SM-PAO in solution with pH below or above the isoelectric point of SM-PAO sol (∼ pH 5). The collection of uranium-loaded adsorbent is realized by virtue of the dissolution-precipitation transformation of the SM-PAO. A record high adsorption capacity, 2221.9 mg-U/g-Ads, is achieved within several minutes’ interaction and the bonding mechanism of adsorption is explained by the X-ray photoelectron spectroscopy. An automatic cleaning of uranium-polluted wastewater to potable water is demonstrated to show the great potential of SM-PAO adsorbent for practical application.

Cuttlefish ink loaded polyamidoxime adsorbent with excellent photothermal conversion and antibacterial activity for highly efficient uranium capture from natural seawater

Owing to the abundant uranium reserves in the oceans, the collection of uranium from seawater has aroused the widespread interest. Compared to the uranium extraction from ore, uranium collection from seawater is a more environmentally friendly strategy. The amidoxime (AO) functional group has been considered as one of the most efficient chelating groups for uranium capture. In this work, by drawing upon the photothermal character and antibacterial activity of cuttlefish ink, a cuttlefish ink loaded polyamidoxime (CI-PAO) membrane adsorbent is developed. Under one-sun illumination, the CI-PAO membrane shows a high extraction capacity of 488.76 mg-U/g-Ads in 500 mL 8 ppm uranium spiked simulated seawater, which is 1.24 times higher than PAO membrane. The adsorption rate of CI-PAO membrane is increased by 32.04%. Furthermore, exhibiting roughly 75% bacteriostatic rate in composite marine bacteria, the CI-PAO shows a dramatically antibacterial activity, which effectively prevents the functional sites on the adsorbent surface from being occupied by the biofouling blocks. After immersing in natural seawater for 4 weeks, light-irradiated CI-PAO gave high uranium uptake capacity of 6.17 mg-U/g-Ads. Hence, the CI-PAO membrane adsorbent can be considered as a potential candidate for the practical application for uranium extraction from seawater.

Molecular docking studies of Amidoxime-containing heterocyclic compounds from Zinc database against homology modelled PfADSL

Malaria remains one of the most infectious life-threatening diseases in the world. The lingering effect of drug resistance by malarial parasites, especially Plasmodium falciparum, has made it essential for the continuous search for novel antimalarial drugs that can act on new protein targets and through new modes of action. Amidoxime functional groups have, in recent years, shown to be good incorporations in heterocyclic backbones due to their vast biological activities. Hence, the antimalarial activities of some amidoxime-containing heterocyclic compounds have been predicted using molecular docking studies to determine the binding affinities and the inhibition constants of the compounds. The amidoxime-containing compounds were downloaded from the ZINC database and docked, using Auto Dock vina, against the active sites of homology modelled Plasmodium falciparumadenylosuccinate lyase (PfADSL) as obtained from the SWISS-MoDeL. The grid box was constructed using 80, 80, and 80, pointing in x, y, and z directions, respectively, with a grid point spacing of 0.375 A. The post-docking analysis, which entails determining the hydrogen bond formed and the bond length between the compounds and the protein target, was carried out using AutoDockTools, LigPlot and PyMOLmolecular viewer. The docking studies showed that the compounds possess binding affinities ranging from -8.6 to- 5.7 kcal/mol, with ZINC2268942 having the lowest binding affinity. The presence of the amidoxime-functional group on the best hit contributed significantly to the hydrogen bonds formed between the compound and the binding sites of PfADSL,which were observed atThr 124D, Ser 125D, Thr 172C, His 173C, Gln 250D, and Ser 299A. The results obtained from the molecular docking studies will be helpful in the development of a potential antimalarial drug that can target PfADSL after careful experimental validation of the target, then in vitro and in vivo screening.

Chromium(VI) adsorption–reduction using a fibrous amidoxime-grafted adsorbent

To comply with regulations and mitigate environmental pollution, efficient technologies are required for treating chromium-contaminated industrial wastewater. To develop a safe and simple method for the reduction of toxic chromium(VI) to the less harmful chromium(III), we proposed using radiation-induced graft polymerization. This method allows for any functional group to be introduced into conventional polymeric materials, which enables the synthesis of solid adsorbents with good handling properties. Herein, we synthesized a fibrous adsorbent with amidoxime functional groups that have a high affinity for chromium, and investigated the changes in the chromium valence state over time in the amidoxime-grafted adsorbent. Fourier transform infrared analysis suggested that the amide groups were oxidized by chromium(VI) and converted to nitro groups. Furthermore, in situ X-ray absorption fine structure analysis revealed that most of the chromium(VI) was reduced to chromium(III) relatively early during the adsorption process, followed by gradual changes in the bonding structure of the amidoxime-chromium complex. Although more than one day was required to completely stabilize the structure of chromium(III), this approach provides a safe method for chromium(VI) removal. Furthermore, because wastewater can be treated via simple circulation with this method, it is easier to operate than coagulation sedimentation or electrochemical methods. Thus, it is expected to contribute to the development of practical technologies for wastewater treatment.

High Selective Isomerization of Glucose to Fructose Catalyzed by Amidoximed Polyacrylonitrile.

The isomerization of glucose to fructose provides an important way to expand the utilization of biomass. Herein, an amidoximated polyacrylonitrile (PAO) with an amidoxime functional group was prepared and used as an active heterogeneous catalyst for the isomerization of glucose to fructose. The PAO was characterized by SEM, XPS, and FTIR. The yield of fructose reached 48.9% with a selectivity of 98.6% for a 5 h reaction in aqueous solution at an initial pH of 6.5 and 85 °C. The pH caused a great influence on the conversion of glucose and selectivity of fructose while a little effect on the yield of fructose in the range of pH 5–10. The activation energy of isomerization reaction was evaluated as 79.7 kJ·mol–1. The catalysis mechanism was proposed, and the synergistic effect of oxime and amino groups played an important role in the isomerization of glucose. PAO maintained good catalytic activity after four cycles.

Functionalized mesoporous carbon nanospheres for efficient uranium extraction from aqueous solutions

The development of effective adsorbents for uranium (VI) extraction from aqueous solutions has received great significance for environmental security. Herein, we reported a versatile and straightforward strategy for the synthesis of amidoxime-functionalized mesoporous carbon nanospheres (MCNs-AO). This method utilized the chemical grafting of amidoxime functional groups to the mesoporous carbon nanospheres. The resultant MCNs-AO was highly active, selective, and recyclable adsorbent for U(VI) extraction from aqueous solutions. MCNs-AO showed the maximum adsorption capacity of 627.2 mg·g1 at 298 K and pH = 5.5, much higher than MCNs (58.2 mg·g1) and other materials. Batch and fixed-bed column experiments indicated that the highly accessible amidoxime groups serving as the active sites are critical to U(VI) adsorption performance on MCNs-AO. This proof-of-concept study opens a new way to synthesize highly effective, low-cost, and durable adsorbents for the efficient extraction of U(VI).

Partially Reduced Graphene Oxide Modified with Polyacrylonitrile for the Removal of Sm3+ from Water

An in situ emulsion polymerization method was used for the synthesis of polyacrylonitrile nanoparticles amino-functionalized partially reduced graphene oxide (PAN-PRGO). After that, hydrolyzed polyacrylonitrile nanoparticles amino-functionalized partially reduced graphene oxide (HPAN-PRGO) nanocomposite was achieved by the modification of nitrile groups of the composite polymer chains to carboxylic groups, aminoethylene diamine, and amidoxime functional groups through partial hydrolysis using a basic solution of sodium hydroxide for 20 min. Different synthesized materials were characterized and compared using well-known techniques including transmission electron microscope (TEM), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), Raman spectra, and X-ray diffraction (XRD). The nanocomposite was structured through the interaction between acrylonitrile’s (AN) nitrile groups and amino-functionalized graphene oxide nanosheets’ amino groups to successfully graft polyacrylonitrile over the surface of functionalized nanosheets as approved by characterization techniques. The synthesized composite was examined for the removal of samarium ions (Sm3+) from water. Different experimental conditions including pH, contact time, initial concentration, and adsorbent dose were investigated to determine the optimum conditions for the metal capture from water. The optimum conditions were found to be a contact time of 15 min, pH 6, and 0.01 g of adsorbent dosage. The experimental results found, in a good agreement with the Langmuir isotherm model, the maximum adsorption capacity of Sm3+ uptake was equal to 357 mg/g. A regeneration and reusability study of synthesized composite up to six cycles indicated the ability to use HPAN-PRGO nanocomposite several times for Sm3+ uptake. The obtained results prove that this polymer-based composite is a promising adsorbent for water treatment that must be studied for additional pollutants removal in the future.

Amidoximated wooden solar evaporator for high-efficiency nuclear wastewater treatment.

The efficient removal of uranium (VI) (UO22+) is of great significance to the ecological environment. However, there is still a lack of efficient adsorption materials to remove UO22+ in wastewater economically. Because natural basswood has high porosity, natural hydrophilicity, and abundant surface functional groups, wood as a support material has a good application prospect in water treatment. In the present work, the amidoxime functional group (AO) is grafted to the hydroxyl group of the wood fiber (AO-wood). A carbon layer is formed on the surface of the basswood by heating, and some Ag nanoparticles with good optothermal effect are added to the wood tunnel (Ag-C-AO-wood). Ag-C-AO-wood is used for efficient wastewater treatment under light conditions. The adsorption kinetic of Ag-C-AO-wood is 4.6 h under one irradiation, which is 7 times faster than AO-wood. It has approached or even surpassed some traditional carbon materials with stirring. This method is expected to break the traditional stirring method. Ag-C-AO-wood can not only remove uranium up to 82% but also have a good removal efficiency (27%) on iodide ions. More importantly, due to basswood characteristics, it is possible to large-scale preparation and explore its potential application value in wastewater.

Postsynthetically Modified Polymers of Intrinsic Microporosity (PIMs) for Capturing Toxic Gases.

Polymers of intrinsic microporosity (PIMs) are promising materials for gas adsorption because of their high surface area, processability, and tailorable backbone. Specifically, nitrile groups on the backbone of PIM-1, an archetypal PIM, can be converted to other functional groups to selectively capture targeted gas molecules. Despite these appealing features of PIMs, their potential has mainly only been realized for the separation of nontoxic gases. Here, we prepared PIM-1 materials modified with carboxylic acid and amidoxime functional groups and investigated their performance as adsorbents for the capture of ammonia (NH3) and sulfur dioxide (SO2) gases. After determining the Brønsted acidity or basicity of the PIMs from potentiometric acid-base titrations, which can be correlated with affinity for acidic or basic toxic gases, we explored the uptake capacity toward NH3 and SO2, respectively. Gas sorption studies revealed that the carboxylated PIM showed higher affinity toward NH3 through the incorporation of Brønsted acid sites, while the amidoxime functionalized PIM exhibited affinity toward SO2 through the installed of slightly basic functional groups. Overall, this study highlights new insight into PIMs as solid sorbent materials for capturing toxic gases, which can be transferred to their potential use in practical applications, such as personal protective equipment or air filtration.

Poly amidoxime functionalized carbon nanotube as an efficient adsorbent for removal of uranium from aqueous solution

The poly amidoxime functionalized carbon nanotube (PAO@CNT) was prepared, characterized, and applied for the adsorption of uranium from aqueous solutions. In this paper, a new preparation method of amidoxime-derived adsorbent was proposed to overcome the shortcomings of the rational design and synthesis of amidoxime-based adsorbents, which resulted in a low adsorption capacity. The homogeneous reaction and nano-skeleton support strategy were utilized to create amidoxime-rich polymer and its remold on the surface of carbon nanotube, composing the porous adsorbent. The results showed that PAO@CNT was an efficient adsorbent for uranium adsorption due to its abundant amidoxime functional group, and the adsorption capacity towards uranyl ions was significantly enhanced with the sequential improvement. With abundant chelating groups and porous structure (SBET = 58.169 m2/g), the adsorbent had a high adsorption capacity (~247 mg/g at pH = 4) and kinetics (equilibrium time: 120 min) for uranyl ions. The XPS and FT-IR spectra revealed the participation of N and O atoms of amidoxime groups in the adsorption of uranyl ions.