High Reusability Research Articles

Dual Dynamic Cross-Linked Epoxy Vitrimers Used for Strong, Detachable, and Reworkable Adhesives.

Novel reprocessable thermosetting adhesives (RTAs), which combine high adhesive strength, reusability, disassembly, and recyclability features, have attracted increasing attention. However, developing RTAs with a rapidly adhesive rate while ensuring high adhesive strength and self-healing ability is still a significant challenge. Here, we prepared a novel vitrimer called DAx-DTSAy, which can be used as an RTA. First, by adjusting the ratio of rigid and flexible segments, maximum tensile strength reached 35.92 MPa. Second, the combined effect of dynamic hydroxyl ester bonds and dynamic disulfide bonds resulted in a rapid stress relaxation behavior, with a complete relaxation time 13.6 times shorter than a vitrimer only cross-linked with hydroxy ester bonds. This feature endowed its good self-healing and reprocessing capabilities. After self-healing at 180 °C, the maximum healing rate of mechanical properties was 91.8%. After three reprocesses, the maximum recovery rate of tensile strength was 120.2%. Furthermore, the combination of rigid and flexible segments and the synergistic effect of dual dynamic covalent bonds made DAx-DTSAy capable of use as a high-performance RTA. The lap shear strength of a DAx-DTSAy film on stainless steel reached 18.18 MPa after 15 min, with a recovery rate of 91.9% after 5 rebonding cycles. Additionally, DAx-DTSAy can be disassembled in chemical agents and exhibited better insulation properties compared to traditional epoxy resins. DAx-DTSAy can be employed as a novel high-performance adhesive in applications such as electronic devices and transportation, contributing to the development of thermosetting adhesives toward recyclability and sustainability.

Weak acid hydrolysis strategy to oxygen vacancy enriched BiOBrnI1-n nanosheet for photodegrading various contaminants

BiOBrnI1-n solid solution enriched with oxygen vacancies (OVs) was obtained using simple hydrolysis method and exhibited excellent ability to remove various contaminants, inclusive of bisphenol A (BPA), rhodamine B (RhB), methyl orange (MO), tetracycline hydrochloride (TCH) and sulfamethazine (SMT). The photocatalytic degradation efficiency of optimal BiOBrnI1-n catalyst for BPA is 128 and 13.8 times higher than that of BiOBr and BiOI, respectively. The excellent degradation activity benefits from the suitable energy band potential, interior electric field and superior charge separation efficiency. The test of catalytic cycles confirms the high reusability of BiOBrnI1-n. Photoinduced h+, ·O2−, and e− serve as reactive species in the degradation process. This work provides an effective photocatalyst for the photodegradation of various contaminants.

Cellulose nanocrystal-infused polymer hydrogel imbued with ferric-manganese oxide nanoparticles for efficient antinomy removal

Antimony is a highly poisonous pollutant that needs to be removed from water to ensured safety. In this work, we have fabricated a novel adsorbent, the ferric-manganese oxide (FeMnOx) nanoparticles embedded cellulose nanocrystal-based polymer hydrogel (FeMnOx @CNC-g-PAA/qP4VP, denoted as FMO@CPqP), specifically engineered for the remediation of antimony-laden water. Comprehensive evaluations have been conducted to investigate the efficacy of the FMO@CPqP hydrogel in removal of antimony from water. The hydrogel exhibits superior affinity for antimony, with maximum adsorption capacities of 276.1 mg/g for Sb(III) and 286.8 mg/g for Sb(V). The adsorptive dynamics, governed by the kinetics and isotherm analyses, elucidate that the immobilization of both Sb(III) and Sb(V) is facilitated through a homogeneous and monolayer chemisorption mechanism. The hydrogel has a three-dimensional interconnected porous structure and exhibits good swelling behavior, which facilitates the rapid absorption of antimony ions by this high surface area hydrogel into the channels. Furthermore, various effects, including the oxidation and inner-sphere coordination mediated by FeMnOx NPs and the electrostatic attractions of the quaternized P4VP chains, promote the immobilization of antimony species. Owing to its high removal efficiency, stability and reusability, the FMO@CPqP hydrogel emerges as an exemplary candidate for the removal of antimony contaminants in water treatment processes.

Polyethyleneimine and chitosan incorporated winter melon-derived biochar composite gels for highly selective capture of uranium(VI)

This work synthesized polyethyleneimine and chitosan modified winter melon-derived biochar (PEI-CTS@WBC) using chemical crosslinking method for uranium(VI) removal. The factors influencing uranium(VI) adsorption by PEI-CTS@WBC, including pH, adsorbent dosage, time, temperature, and initial U(VI) concentration were explored. The material's performance was characterized, and the underlying mechanism of U(VI) removal was analyzed using various techniques. Compared with other reported adsorbents, the maximum adsorption capacity of PEI-CTS@WBC for U(VI) was 411.44 mg g−1, which was higher than most existing adsorbents. The dynamics studies showed that adsorption was more in line with the second-order kinetic model, indicating that chemical adsorption was the main process. The Kd and SU value of U(VI) by PEI-CTS@WBC could reach 11194.44 mL g−1 and 76.47 % respectively, which exhibited a high selective adsorption characteristics for U(VI) in aqueous solutions. The XPS analysis demonstrated that the adsorption process was primarily due to the formation of stable complexes with N-H, N-C, C-O and O-H. This research showed that the introduction of polyethyleneimine and chitosan greatly improved the adsorption effect of WBC on U(VI). PEI-CTS@WBC had high selective adsorption characteristics and good reusability for U(VI) in aqueous solutions. PEI-CTS@WBC was an economical, efficient and stable composite material. These findings provided a theoretical basis for the treatment of wastewater contaminated with U(VI).

Enhancing catalyst stability: Immobilization of Cu–Fe catalyst in sodium alginate matrix for methyl orange removal via Fenton-like reaction

This study aims to enhance the stability and effectiveness of heterogeneous catalysts in Fenton-like reactions, explicitly addressing the acidity limitations inherent in traditional Fenton processes. Copper-iron was synthesized through co-precipitation, and a catalyst bead was produced from hydrogel formation. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirm phases in the bimetallic Copper-iron, aligning with the intended composition. Modification with alginate led to reduced metal leaching compared to the bare bimetallic counterpart, as confirmed by atomic absorption spectroscopy (AAS). Additionally, Fourier-transform infrared spectroscopy (FTIR) revealed the deactivation of alginate through the disappearance of carboxyl groups, indicating the depolymerization of the catalyst bead. Under the suggested conditions (Methyl Orange concentration of 25 mg/L, initial solution pH of 7, 2 g/L catalyst loading, concentration of hydrogen peroxide 100 mM in a 120-min reaction time), the catalyst demonstrated remarkable decolorization efficiency of Methyl Orange, achieving 97.67 %. Further highlighting its practicality, the catalyst exhibited outstanding reusability over four cycles under identical conditions, showcasing robust immobilization capabilities and sustained performance. Notably, the catalyst's magnetic properties facilitated easy separation using an external magnet. In conclusion, the developed catalyst beads offer a solution with high reusability, magnetic separability, and reduced iron leaching. The advantageous characteristics underscore its potential as a heterogeneous catalyst for wastewater treatment applications, warranting further exploration under practical conditions.

A Study about Perceptions of Kimono among College Students and Kimono Enthusiasts: Is It Difficult to Move in a Kimono?

Kimono is being reevaluated for its sustainability aspects, such as having fewer offcuts in the production process due to its structural differences from Western-style clothes and its high reusability due to the adaptability to individuals' body shapes. On the other hand, once a common attire for daily wear in Japan, kimono has transitioned to being worn only on special events and the kimono-related industry has also shrunk. To stimulate demand for kimono, it is essential to familiarize younger generations with its potential as daily wear. A questionnaire survey on perceptions of kimono was conducted among two groups in Japan: 211 college students and 50 kimono enthusiasts. The questionnaire included demographic questions and psychometric scales, primarily focusing on their kimono experiences, challenges associated with wearing kimono, their perceptions of kimono and Western-style clothes, and their attitudes towards kimono. The results revealed that a majority of students had worn kimono before, though they found it difficult to move while wearing it. In contrast, kimono enthusiasts evaluated it as easier to move, hard to become disheveled, and casual. They also rated the ease of wearing Western-style clothes lower compared to students, and this tendency intensified with the length of enthusiast experience. Furthermore, the findings indicated that enthusiasts regarded the kimono more as daily wear compared to students, while still deriving enjoyment from it as formal attire in special events. These results suggest that the cognition that Western-style clothes are easy to move and kimono is not may change with experiences. Therefore, providing opportunities for people in Japan to acquire how to wear kimono in comfortable ways possibly impacts their perceptions of kimono.

Zirconium-Based Metal-Organic Frameworks with Free Hydroxy Groups for Enhanced Perfluorooctanoic Acid Uptake in Water.

Perfluorooctanoic acid (PFOA) is a highly recalcitrant organic pollutant, and its bioaccumulation severely endangers human health. While various methods are developed for PFOA removal, the targeted design of adsorbents with high efficiency and reusability remains largely unexplored. Here the rational design and synthesis of two novel zirconium-based metal‒organic frameworks (MOFs) bearing free ortho-hydroxy sites, namely noninterpenetrated PCN-1001 and twofold interpenetrated PCN-1002,are presented. Single crystal analysis of the pure ligand reveals that intramolecular hydrogen bonding plays a pivotal role in directing the formation of MOFs with free hydroxy groups. Furthermore, the transformation from PCN-1001 to PCN-1002 is realized. Compared to PCN-1001, PCN-1002 displays higher chemical stability due to interpenetration, thereby demonstrating an exceptional PFOA adsorption capacity of up to 632mgg-1 (1.53mmolg-1), which is comparable to the reported record values. Moreover, PCN-1002 shows rapid kinetics, high selectivity, and long-life cycles in PFOA removal tests. Solid-state nuclear magnetic resonance results and density functional theory calculations reveal that multiple hydrogen bonds between the free ortho-hydroxy sites and PFOA, along with Lewis acid-base interaction, work collaboratively to enhance PFOA adsorption.

Copper-Based Bio-MOF/GO with Lewis Basic Sites for CO2 Fixation into Cyclic Carbonates and C-C Bond-Forming Reactions.

Several measures, including crude oil recovery improvement and carbon dioxide (CO2) conversion into valuable chemicals, have been considered to decrease the greenhouse effect and ensure a sustainable low-carbon future. The Knoevenagel condensation and CO2 fixation have been introduced as two principal solutions to these challenges. In the present study for the first time, bio-metal-organic frameworks (MOF)(Cu)/graphene oxide (GO) nanocomposites have been used as catalytic agents for these two reactions. In view of the attendance of amine groups, biological MOFs with NH2 functional groups as Lewis base sites protruding on the channels' internal surface were used. The bio-MOF(Cu)/20%GO performs efficaciously in CO2 fixation, leading to more than 99.9% conversion with TON = 525 via a solvent-free reaction under a 1 bar CO2 atmosphere. It has been shown that these frameworks are highly catalytic due to the Lewis basic sites, i.e., NH2, pyrimidine, and C═O groups. Besides, the Lewis base active sites exert synergistic effects and render bio-MOF(Cu)/10%GO nanostructures as highly efficient catalysts, significantly accelerating Knoevenagel condensation reactions of aldehydes and malononitrile as substrates, thanks to the high TOF (1327 h-1) and acceptable reusability. Bio-MOFs can be stabilized in reactions using GO with oxygen-containing functional groups that contribute as efficient substitutes, leading to an expeditious reaction speed and facilitating substrate absorption.

High performance removal of chlorophenols from an aqueous solution using an enzymatic membrane bioreactor

Organochlorides and particularly chlorophenols are environmental pollutants that deserve special attention. Enzymatic membrane bioreactors may be alternatives for efficiently removing such hazardous organochlorides from aqueous solutions. We propose here a novel enzymatic membrane bioreactor comprising an ultrafiltration membrane GR81PP, electrospun fibers made of cellulose acetate, and laccase immobilized using an incubation and a fouling approach. Configurations of this biosystem exhibiting the highest catalytic activity were selected for removal of 2-chlorophenol and 4-chlorophenol from aqueous solution in an enzymatic membrane bioreactor under various process conditions. The highest removal of chlorophenols, at 88% and 74% for 2-chlorophenol and 4-chlorophenol, respectively, occurred at pH 5 and 30 °C in the GR81PP/cellulose acetate/laccase biosystem with enzyme immobilized by the fouling method. Furthermore, the GR81PP/cellulose acetate/laccase biosystem with enzyme immobilized by the fouling method exhibited significant reusability and storage stability compared with the biosystem with laccase immobilized by the incubation method. The mechanism of enzyme immobilization is based on pore blocking and cake-layer formation, while the mechanism of chlorophenols removal was identified as a synergistic combination of membrane separation and enzymatic conversion. The importance of the conducted research is due to efficient removal of hazardous organochlorides using a novel enzymatic membrane bioreactor. The study demonstrates the biosystem's high catalytic activity, reusability, and stability, offering a promising solution for environmental pollution control.

Highly efficient catalytic reduction of organic dyes, Cr (VI) and 4‐nitrophenol, and photocatalytic degradation of MB by an inorganic–organic hybrid polyoxometalate

It is urgent to remove various pollutants from the water environment. Therefore, an inorganic–organic hybrid polyoxometalate (POM) [PMoVI6MoV2VIV8O44{Co(2,2′‐bipy)2(H2O)}4]‐[PMoVI4MoV4VIV8O44{Co(2,2′‐bipy)2(H2O)}2]·4H2O (PMoVCo) was fully characterized by XRD, XPS, FTIR, SEM, BET and zeta potential techniques, and applied for the catalytic reduction of hazardous methylene blue (MB), methyl orange (MO), rhodamine B (RhB), Cr (VI) and 4‐nitrophenol (4‐NP) in aqueous media over NaBH4 under mild condition. The removal ratios were 99.6% (MB, 2.5 min), 97.0% (MO, 3.0 min), 92.5% (RhB, 2.0 min), 89.2% (Cr (VI), 2.0 min) and 89.6% (4‐NP, 2.5 min), respectively. The pseudo‐first‐order rate constants of the reactions were 1.992 min−1 (MB), 0.810 min−1 (MO), 1.768 min−1 (RhB), 1.186 min−1 (Cr (VI)) and 0.934 min−1 (4‐NP), respectively. Additionally, PMoVCo exhibited satisfactory catalytic activity for the photo‐Fenton‐like degradation of MB at neutral pH under visible light irradiation with a degradation rate up to 99.9% in 480 min. The results of the recycling experiment prove that PMoVCo has high catalytic reusability. Moreover, the possible mechanisms of the catalytic reduction and degradation processes were proposed. The catalytic activities of PMoVCo are better than other inorganic–organic hybrid POMs. All the results of this study indicate that PMoVCo has the potential to be a satisfactory catalyst for wastewater remediation via reduction or photocatalytic degradation.

Processable, reversible, and reusable 100 % bio-based pressure sensitive adhesives using nanostarch

We developed a 100 % bio-based pressure sensitive adhesive (PSA) possessing strong adhesion, as well as reusability, recyclability, and on-demand removability. The adhesive formulation is based on a colloidal mixture of starch (specifically amylopectin) nanoparticles and cellulose nanofibrils, combined with an aqueous solution of sorbitol and glycerol. Optimization of water supply and substitution of water with hygroscopic glycerol were implemented to address the challenges caused by the use of high water contents in hydrogels. By leveraging physical crosslinking through hydrogen bonding, we achieved high adhesion strength, reversibility, and reusability with 100 % bio-based materials. The optimal formulation demonstrates excellent rheological and adhesion properties, which are comparable to petrochemical-based adhesives in terms of tack, peel strength, and shear strength. While there are areas for further optimization, this work provides a foundational step towards a more sustainable adhesive industry.

Enhanced Photocatalytic Removal of U(VI) from Real Radioactive Wastewater by Modulating the Surface Charge Microenvironment in Porphyrin-Based Hydrogen-Bonded Organic Framework.

Reduction of soluble U(VI) to insoluble U(IV) based on photocatalysts is a simple, environmentally friendly, and efficient method for treating radioactive wastewater. The present study involved the systematic comparison of the photoelectric properties of three metalloporphyrins with different metal centers and the synthesis of a novel porphyrin-based hydrogen-bonded organic framework (Ni-pHOF) photocatalyst by modulating the surface charge microenvironment in porphyrin for enhanced photocatalytic removal of U(VI) from wastewater. Compared to the metal-free HOF, the surface charge microenvironment around the Ni atom in Ni-pHOF accelerated the reduction kinetics of U(VI) under visible light illumination at the initial moment, showing a high removal rate, even in air. The removal rate of U(VI) from aqueous solution by Ni-pHOF can achieve over 98% in the presence of coexisting nonoxidizing cations and only decreased by less than 8% after five cycles, exhibiting high selectivity and good reusability. Furthermore, Ni-pHOF can remove 86.74% of U(VI) from real low-level radioactive wastewater after 120 min of illumination, showcasing practical application potential. Density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) spectra indicated that modulating the surface charge microenvironment in Ni-pHOF through porphyrin metallization is conducive to improving the charge separation efficiency, prompting more e- and •O2- to participate in the reduction reaction of U(VI). This work provides new insights into the metallization of porphyrin-based HOFs and paves a new way for the tailoring of porphyrin-based HOFs/COFs by modulating the surface charge microenvironment to achieve efficient recovery of U(VI) from real radioactive wastewater.

A facile synthesis of bimetallic Ni/Co-BTC hollow MOFs for effective removal of congo red

ABSTRACT In this work, we employ an eco-friendly and highly efficient method for the successful removal of anionic azo dye (CR) using emerging Ni/Co-BTC hollow Metal-Organic Frameworks (MOFs). The MOFs was developed via a solvothermal synthesis method. Various kinetic models, adsorption capacities, isotherms (Langmuir and Freundlich), and thermodynamic stability assessments were used to predict the adsorption mechanism and the types of interactions present between CR dyes and Hollow MOFs. Our findings suggest that the adsorption process follows Freundlich isotherm, with PSO kinetic models indicating chemisorption and a maximum Langmuir adsorption capacity of 168.03 mgg−1. We observed a removal efficiency of 74% in neutral medium and 85% in acidic medium. Thermodynamic studies reveal the spontaneity of the process with endothermic enthalpy, attributed to the hydrogen bonding and electrostatic interactions between the dye molecule and the adsorbent. Furthermore, to investigate practical applicability, we conducted studies in real water and dye mixtures. All studies demonstrated that the prepared Ni/Co-BTC hollow MOFs show promising potential adsorbents for the CR dye removal from the wastewater, owing to their high efficiency and reusability.

UNLOCKING THE POTENTIAL OF EXISTING BAMBOO SCAFFOLD CONNECTIONS: A COMPREHENSIVE REVIEW ON REUSABILITY

Bamboo scaffolding is a sustainable alternative to traditional scaffolding materials due to its low carbon footprint, renewability, and strength. Reusable connections are crucial to optimize its sustainability benefits. This review provides a comprehensive overview of the reusability potential of existing bamboo scaffold connections, exploring different connection types, factors influencing reusability, benefits and challenges, and current research and development efforts. Several factors influence the reusability of bamboo scaffold connections, including the design of connections to accommodate mid-culm attachment of secondary components, which is challenging for many existing connection types. Reusing bamboo scaffold connections offers significant sustainability and cost-effectiveness benefits, reducing the demand for new materials and minimizing construction waste. Friction-tight lashing, the most popular and adaptable bamboo scaffold connection method together with mechanical connectors to alleviate problems in traditional friction-tight lashing, offers high reusability potential. More advanced mechanical connections, such as notched and pierced connections, are also being explored for their reusability potential. Ongoing research and development efforts focus on innovative approaches such as three-dimensional printing, parametric software, and glue bonding for custom joint systems to improve the reusability of bamboo scaffold connections. By addressing the challenges and leveraging ongoing research and development efforts, reusable bamboo scaffold connections can play a crucial role in sustainable construction practices.

Probe into a novel surfactant-free microemulsion system of ethylene glycol monobutyl ether + water + diesel for crude oil removal and recovery from oily sludge

A novel surfactant-free microemulsion (SFME) system was proposed in this study, and applied in the crude oil removal and recovery from oily sludge (OS). Based on an investigation of the SFME phase behavior and solution properties, a complete ternary phase diagram was constructed. The SFME with three-liquid phase equilibrium (Winsor III type) was selected for the treatment of OS to achieve simultaneous efficient removal (up to 95.1 %) and recovery (up to 83.2 %) of crude oil. The SFME could be reused continuously for OS treatment without purification. The removal efficiency could still keep >75.9 % after 5 times of reuse, showing high reusability. The detached crude oil could be automatically recovered based on the phase equilibrium principle without additional separation. In the washing experiments, single-factor and multi-factor orthogonal tests were applied to investigate the effects of different experimental conditions on oil removal efficiency and determine the optimal experimental scheme. The treated OS was sufficiently decontaminated according to the morphology, composition, and properties analysis by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle. The composition of the recovered crude oil was identical to that of commercial crude oil according to gas chromatography–mass spectrometry analysis, showing a high recovery value. The kinetic analysis revealed that crude oil desorption experienced three main stages: membrane diffusion, intra-particle diffusion and surface desorption, and identified the chemisorption was the main interaction between the oil–soil. Finally, the mechanism of SFME action was assessed for dissolution and activation based on ultra-low IFT.

Biodiesel production from spent coffee grounds utilizing pomegranate/orange peel biochar as a green and renewable nanocatalyst: Compression ignition engine performance and emission

In this research, a novel pomegranate/orange peel-derived activated carbon (POPAC) green heterogeneous nanocatalyst was developed for the conversion of spent coffee grounds oil (SCGO) into biodiesel by ultrasonication and its application in diesel engine characteristics. The surface and texture attributes of the POPAC green nanocatalyst were scrutinized employing SEM, EDX, CO2-TPD, XRD, TEM, FTIR, Raman, and BET. Based on the response surface methodology (RSM) outcomes, the highest biodiesel efficiency employing POPAC green nanocatalysts was 95.24 %, which was attained at optimal conditions (i.e., molar proportion of 11.02, nanocatalyst content of 2.56 wt%, ultrasonic time of 30.77 min, and temperature of 60 0C). Moreover, the stability assessment demonstrated the high reusability of POPAC green nanocatalysts, with biodiesel efficiency remaining at 87.43 % even after the 7th round. Further, the kinetic survey exhibited that the biodiesel synthesis is endothermic and the conversion rate is enhanced by boosting the temperature. Besides, the impact of merging biodiesel with the diesel/biodiesel combination at diverse torques was scrutinized on the emission of exhaust output (e.g., UHC, NOx, CO, and CO2) and engine crucial characteristics (i.e., BP, EGT, BTE, and BSFC), and encouraging results were acquired. Briefly, due to special attributes including high catalytic performance, substantial recyclability, and eco-friendliness, POPAC green nanocatalyst are highly suggested for biodiesel generation.

Magnetic surface-imprinted polymer microspheres coupled with HPLC-MS/MS for sensitive detection of amphetamine-type drugs in water

Magnetic surface imprinted polymer microspheres (Fe3O4@MIPs) were successfully synthesized via Pickering emulsion polymerization, utilizing N-Methylphenethylamine as a surrogate template for amphetamine-type drugs. Fe3O4@MIPs not only possessed excellent dispersibility and enough magnetic properties in aqueous solutions, but also displayed good selectivity towards six amphetamines, with an imprinting factor ranging from 1.8 to 2.6. The adsorption kinetics closely aligned with the pseudo-second-order model, and the adsorption efficiency exceeds 80 % for each amphetamine at equilibrium. Fe3O4@MIPs were then employed as the efficient adsorbents for the extraction of amphetamine drugs. Extraction parameters, including sample pH, the mass of adsorbent, and the type and volume of eluting solvent, were carefully optimized. In combination with the high performance liquid chromatography tandem triple quadrupole mass spectrometry (HPLC-MS/MS), a selective magnetic solid-phase extraction (MISPE) method utilizing Fe3O4@MIPs was developed for the detection of six amphetamines in water samples. The limits of detection and limits of quantitation were determined to be 5.2∼23 ng L−1 and 17∼77 ng L−1, respectively. Recoveries for the six target drugs from lake water and sewage samples fell within the range of 87.2∼110 %. Additionally, the MISPE-HPLC-MS/MS method exhibited excellent repeatability, with a precision below 8.5 % at two spiking levels. The prepared Fe3O4@MIPs possessed the advantages of high selectivity, straightforward preparation, facile separation and good reusability, and was highly suitable for the efficient extraction of amphetamine-type substances in complex environmental water.

Nitrogen-rich covalent-organic-framework as a recyclable heterogenous catalyst for the efficient cycloaddition of carbon dioxide with epoxides

Carbon dioxide (CO2) can be chemically converted into high-value products, which is not only helps to ease the environmental problems instigated by global warming and has an optimistic effect on economies around the planet. The production of cyclic carbonates is regarded as a promising approach to convert CO2 through the cycloaddition of CO2 with epoxides. However, a major obstacle in this process is the synthesis of environmentally friendly and highly effective heterogeneous catalysts. Here, a novel nitrogen-rich covalent organic framework (CP-COF) was firstly synthesized through a polymerization method of piperazine and cyanuric chloride with 1, 4‐dioxane and used for the aforesaid reaction. A number of analytical methods were employed to verify the chemical composition and the structure of the catalyst. The CP-COF catalyst possessed a significant amount of active nitrogen sites and hydrogen bond donors in it, resulting in a high level of reactivity for the cycloaddition reaction of CO2 with epichlorohydrin in the absence of any solvent and metals, and the yield of chloropropene carbonate (CPC) reached 99 % at 110 ℃, 6 h and 1 MPa CO2 pressure. The CP-COF sample exhibited commendable activity towards a range of epoxides. Moreover, it showed high reusability for the reaction without any loss in the catalytic efficiency.

Nano temperature-switchable supramolecular solvent: Preparation, characterization and application in efficient extraction and enrichment of phytochemicals

In this study, a nano temperature-switchable supramolecular solvent (NTS-SUPRAS) system was designed, prepared and characterized for efficient extraction and enrichment of phytochemicals, the extraction mechanism was also investigated. The NTS-SUPRAS was synthesized by natural deep eutectic (NADES), 1,2-Propanediol and water, then the ternary phase diagrams were plotted according to their mass fractions. Dynamic light scattering (DLS), conductivity and FT-IR were used to characterize the solvent, and an exciting discovery was the nanoscale of NTS-SUPRAS. The particle size of its reverse micelles self- aggregated was positively correlated to the water content, which was increased from 3.8 nm to 77.9 nm as the water content increased from 5 % to 20 %. Temperature-switchable of NTS-SUPRAS was proved by the appearance of phase separation when regulate temperature from 25 °C to 10 °C. Then, six phytochemicals in Cajanus cajan(Linn.) leaves were efficiently extracted and enriched by vortex-assisted extraction. The extraction factors such as solid–liquid ratio, vortex time, NADES content and water content were optimized using the one-factor optimization method and response surface analysis to obtain the optimal extraction conditions. The results showed that the extraction efficiency of NTS-SUPRAS was 1.18–2.32 folds higher than that of traditional solvents for different polar substances, and the total extraction yield could be reached 21.13 mg/g. The phytochemicals were highly recovered by temperature-switching and macroporous adsorption resin with a recovery rate up to 98.6 %, and the reusability of NTS-SUPRAS could still keep at 90.43 % of the initial one after three cycles. Finally, the extraction mechanism of NTS-SUPRAS was investigated using density functional theory (DFT), founding that the hydrogen bonding between NTS-SUPRAS and the phytochemicals was attributed to the high extraction rate. This nano temperature-switchable supramolecular solvent has the advantages of green, low cost, simple preparation, high extraction rate, easy recycling and good reusability, which is suitable for industrialized application and production. In addition, the nanoscale and the temperature-switchable characteristics also provide new prospects for high-value utilization of phytochemicals.

Dosimetric parameters and radiation tolerance of epitaxial diodes for diagnostic radiology and computed tomography beams

A custom-made EPI diode-based dosimetry system is thoroughly characterized for diagnostic radiology and computed tomography beams. The diode has a thin n-type epitaxial layer (50 μm) grown on a thick (300 μm) Czochralski silicon substrate. It operates as an online radiation dosimeter in the short-circuit current mode. In this case, the key dosimetric quantity is the dose rate, correlated with the output current from the diode exposed to radiation. The corresponding collected charge (the integral of the current signal) is proportional to the dose. Irradiations are performed with the Pantak-Seifert 160HS Isovolt X-ray generator previously standardized by Radcal RC6-RD and RC3-CT ionization chambers. The data gathered with all radiation quality beams confirm the linearity with dose and dose rate despite a slight energy dependence. Independently from the beam energy, the dosimetric parameters of repeatability (<0.3%), long-term stability (0.4%/year), angular response (<3%, ± 5°), dose rate dependence (<3%), and signal-to-noise ratio (≥4900) fully adhere to the IEC 61674 recommendations. Compliance with the accumulated dose stability requirement (1.0%/40 Gy) is almost achieved with the pristine diode and effectively accomplished through radiation conditioning with 60Co gamma rays. Under the latter condition, the lifespan of the diode can easily reach 15 kGy, assuring the high reusability of this diode for diagnostic radiology and computed tomography dosimetry before requiring recalibrations.