ZIF-67 and Biomass-Derived N, S-Codoped Activated Carbon Composite Derivative for High-Effective Removal of Hydroquinone from Water.

Hydroquinone (HQ) in wastewater is of great concern, as it is harmful to human health and threatens the ecological environment. However, the existing adsorbents have low adsorption capacity for HQ. To improve the removal of HQ, N,S-codoped activated carbon-ZIF-67 (NSAC-ZIF-67@C) was synthesized in this study by in situ growth of ZIF-67 on N,S-codoped activated carbon (NSAC) and carbonization. The influence of pH, contact time, and initial concentration on the adsorption behaviors of NSAC-ZIF-67@C on HQ were investigated. Owing to the synergistic effect of abundant active sites and well-developed pore structure, the NSAC-ZIF-67@C achieved a prominent adsorption capacity of 962 mg·g-1 and can still retain high adsorption performance after 5 cycles for HQ, which is superior to that of reported other adsorbents. HQ adsorption follows the pseudo-second-order kinetics model (R2 = 0.99999) and the Freundlich isotherm model. X-ray photoelectron spectroscopy (XPS) analysis before and after adsorption as well as density functional theory (DFT) calculation results showed that pyridinic-N-termini were conducive to the π-π interactions and hydrogen-bonding interactions. Therefore, the adsorption mechanisms of NSAC-ZIF-67@C on HQ involve pore filling, electrostatic attraction, π-π interaction, and hydrogen bonding. This study is expected to provide a reference for designing highly effective adsorbents for wastewater treatment.

High-performance electrosorption of lanthanum ion by Mn3O4-loaded phosphorus-doped porous carbon electrodes via capacitive deionization.

Transition-metal-oxide@heteroatom doped porous carbon composites have attracted considerable research interest because of their large theoretical adsorption capacity, excellent electrical conductivity and well-developed pore structure. Herein, Mn3O4-loaded phosphorus-doped porous carbon composites (Mn3O4@PC-900) were designed and fabricated for the electrosorption of La3+ in aqueous solutions. Due to the synergistic effect between Mn3O4 and PC-900, and the active sites provided by Mn-O-Mn, C/PO, C-P-O and Mn-OH, Mn3O4@PC-900 exhibits high electrosorption performance. The electrosorption value of Mn3O4@PC-900 was 45.34% higher than that of PC-900, reaching 93.02 mg g-1. Moreover, the adsorption selectivity reached 87.93% and 89.27% in La3+/Ca2+ and La3+/Na+ coexistence system, respectively. After 15 adsorption-desorption cycles, its adsorption capacity and retention rate were 50.34 mg g-1 and 54.12%, respectively. The electrosorption process is that La3+ first accesses the pores of Mn3O4@PC-900 to generate an electric double layer (EDL), and then undergoes further Faradaic reaction with Mn3O4 and phosphorus-containing functional groups through intercalation, surface adsorption and complexation. This work is hoped to offer a new idea for exploring transition-metal-oxide @ heteroatom doped porous carbon composites for separation and recovery of rare earth elements (REEs) by capacitive deionization.

Synthesis of Guanine/Vermiculite Two-Dimensional Nanocomposites for Wireless Humidity Sensing in Nut Storage Environment.

Two-dimensional (2D) nanostructures have the advantages of high specific surface area, easy surface functionalization, abundant active sites, and good compatibility with device integration and can be assembled into three-dimensional structures, which are key to the development of high-performance gas sensors. In this study, 2D vermiculite (VMT) nanosheets and guanine (G), two renewable resources with unique chemical structures, were organically combined to fully use the specificity of their molecular structures and functional activities. Driven by the regulation of 2D VMT nanosheets, guanine/vermiculite (G/VMT)-based 2D nanocomposites with controllable pore structure, multiple binding sites, and unobstructed mass transfer were designed and synthesized. The G/VMT nanocomposite material was used as a quartz crystal microbalance (QCM) electrode-sensitive film material to build a QCM-based humidity sensor. G/VMT-based QCM humidity sensor had good logarithmic linear relation (0.9971), high sensitivity (24.49 Hz/% relative humidity), low hysteresis (1.75% RH), fast response/recovery time (39/6 s), and good stability. Furthermore, with a QCM sensor and a specially designed wireless circuit, a wireless humidity detection system transmitting via Wi-Fi allows real-time monitoring of nut storage. This study presents an environmentally friendly, high-performance, miniature 2D nanocomposite sensor strategy for real-time monitoring.

[Preparation of Bamboo-based N, P Co-doped Activated Carbon and Its Lanthanum Ion Adsorption Performance].

Using diammonium hydrogen phosphate as an activator and N and P source and and bamboo chips as the carbon source, N, P co-doped activated carbon was prepared by one-step pyrolysis and used to efficiently remove La3+ in aqueous solutions. The effects of activation temperature and pH value on the adsorption performance of La3+ were analyzed, and the activation and adsorption mechanisms were explored using TG-IR, SEM-EDX, pore structure, XPS, and hydrophilicity. The results showed that diammonium hydrogen phosphate easily decomposed at a high temperature to produce ammonia and phosphoric acid, which activated the material and promoted the increase in the specific surface area and pore volume of the activated carbon. As an N and P source, the addition of diammonium hydrogen phosphate successfully achieved the N, P co-doping of activated carbon, and the introduction of N- and P-containing functional groups was the key to enhance the adsorption of La3+. Among them, graphitic nitrogen could provide interactions between La3+-π bonds, and C-P=O and C/P-O-P could provide active sites for the adsorption of La3+ through complexation and electrostatic interaction. The adsorption of La3+ on N, P co-doped activated carbons was endothermic and spontaneous, and the adsorption process conformed to the Langmuir isotherm and secondary kinetic model. Under the process conditions of an activation temperature of 900℃ and pH=6, the adsorption capacity of the N, P co-doped activated carbon was as high as 55.18 mg·g-1, which was 2.53 times higher than that of the undoped sample, and its adsorption selectivity for La3+ in the La3+/Na+and La3+/Ca2+ coexistence systems reached 93.49% and 82.49%, respectively. Additionally, the removal efficiency remained above 54% after five successive adsorption-desorption cycle experiments.

Tannic Acid-Induced Gelation of Aqueous Suspensions of Cellulose Nanocrystals.

Nanocellulose hydrogels are a crucial category of soft biomaterials with versatile applications in tissue engineering, artificial extracellular matrices, and drug-delivery systems. In the present work, a simple and novel method, involving the self-assembly of cellulose nanocrystals (CNCs) induced by tannic acid (TA), was developed to construct a stable hydrogel (SH-CNC/TA) with oriented porous network structures. The gelation process is driven by the H-bonding interaction between the hydroxyl groups of CNCs and the catechol groups of TA, as substantiated by the atoms in molecules topology analysis and FTIR spectra. Interestingly, the assembled hydrogels exhibited a tunable hierarchical porous structure and mechanical moduli by varying the mass ratio of CNCs to TA. Furthermore, these hydrogels also demonstrate rapid self-healing ability due to the dynamic nature of the H-bond. Additionally, the structural stability of the SH-CNC/TA hydrogel could be further enhanced and adjusted by introducing coordination bonding between metal cations and TA. This H-bonding driven self-assembly method may promote the development of smart cellulose hydrogels with unique microstructures and properties for biomedical and other applications.

Controllable Construction of Temperature-Sensitive Supramolecular Hydrogel Based on Cellulose and Cyclodextrin.

In temperature sensitive hydrogels, the swelling degree or light transmittance of the gel itself changes with variations in ambient temperature, prompting its wide application in controlled drug release, tissue engineering, and material separation. Considering the amphiphilic structure of ß-cyclodextrin (ß-CD), a cellulose-based supramolecular hydrogel with superior temperature sensitivity was synthesized based on a combination of cellulose and ß-CD as well as the host-guest interaction between ß-CD and polypropylene glycol (PPG). In the one-pot tandem reaction process, chemical grafting of ß-CD on cellulose and the inclusion complexation of ß-CD with PPG were performed simultaneously in a NaOH/urea/water system. The obtained supramolecular hydrogel had a lower critical solution temperature (LCST) of 34 °C. There existed covalent bonding between the cellulose and ß-CD, host-guest complexation between the ß-CD and PPG, and hydrogen bonding and hydrophobic interactions between the components in the network structure of the supramolecular hydrogel. The combination of various covalent and non-covalent bonds endowed the resulting supramolecular hydrogel with good internal network structure stability and thermal stability, as well as sensitive temperature responsiveness within a certain range-implying its potential as a smart material in the fields of medicine, biology, and textiles. This work is expected to bring new strategies for the fabrication of cellulose-based thermosensitive materials, benefitting the high-value utilization of cellulose.

A bioinspired hydrogen bond crosslink strategy toward toughening ultrastrong and multifunctional nanocomposite hydrogels.

Developing physical hydrogels with advanced mechanical performance and multi-functionalities as alterative materials for load-bearing soft tissues remains a great challenge. Biological protein-based materials generally exhibit superior strength and toughness owing to their hierarchical structures via hydrogen-bonding assembly. Inspired by natural biological protein materials, tannic acid (TA) is exploited as a molecular coupling bridge between cellulose nanocrystals (CNCs) and poly(vinyl alcohol) (PVA) chains for the fabrication of a bio-based advanced physical hydrogel via strong multiple H-bonds. When exposed to mechanical stress, the sacrificial H-bonds can dissipate energy effectively on the molecular scale via dynamic rupture and reformation, endowing these biomimetic hydrogels with remarkable toughness, ultrahigh strength, large elongation, and good self-recoverability, which are much superior to those of most hydrogen bond-based hydrogels. Moreover, the characteristics of TA endow these biomimetic hydrogels with versatile adhesiveness and good antibacterial properties. This work presents an innovative biomimetic strategy for robust biocompatible hydrogels with superior mechanical strength and functionalities, which holds great promise for applications in tissue engineering and biomedical fields.

Removal of bisphenol A from aqueous solution via host-guest interactions based on beta-cyclodextrin grafted cellulose bead.

ß-CD grafted cellulose bead had been successfully prepared via dropping method, following by cross-linking reaction under mild conditions. The efficient grafting of ß-CD on the cellulose bead made it promising adsorbent toward BPA, which combined the inclusion complexation property of ß-CD and advantages of cellulose bead. The structure of the grafted cellulose bead was characterized by FTIR, XRD and 13C NMR, which confirmed the covalent bonding between cellulose bead and ß-CD. The SEM and BET analysis revealed that the grafting of ß-CD on the cellulose bead maintained the highly porous morphology of cellulose bead, meanwhile enhanced its specific surface area. Thus, the resulting modified cellulose bead presented much higher adsorption capacity toward BPA than pristine cellulose bead, since the presence of ß-CD facilitated the formation of inclusion complexes via host-guest interactions. It was found that the maximum BPA adsorption capacity of grafted cellulose bead was 30.77 mg/g. The adsorption process fitted well with the Langmuir isotherm model and the pseudo-second-order kinetic model. Further studies of ad/desorption experiments revealed that the ß-CD grafted cellulose bead could be regenerated easily in methanol. Based on these results, the adsorbents prepared here can be potentially used in the treatment of micropollutants in water.

Microfibrillated cellulose enhancement to mechanical and conductive properties of biocompatible hydrogels.

A combination of conductive polymer with natural biomass is an ideal alternative to the classical conductive materials. In this study, PPy/SA/TOMFC composite hydrogels were fabricated by incorporation of TEMPO-oxidized microfibrillated cellulose (TOMFC) into the alginate-based matrix along with the in situ polymerization of pyrrole monomer. It was found that the mechanical and conductive properties of the composite hydrogels were associated with the concentration of TOMFC, which facilitated the formation of more compact 3D network structures and the growing of PPy conductive network. The mechanical properties of the synthesized hydrogels were significantly enhanced by incorporation of higher amount of TOMFC. In addition, with the introduction of 5.0 wt% TOMFC, the electrical conductivity of composite hydrogels could be ten times higher than that of PPy/SA hydrogels. Moreover, the obtained PPy/SA/TOMFC hydrogels exhibited tunable swelling properties and good biocompatibility, making them promising candidates for the use as biomaterial.

Palladium-catalyzed condensation of N-aryl imines and alkynylbenziodoxolones to form multisubstituted furans.

A palladium(II) catalyst promotes condensation of an N-aryl imine and an alkynylbenziodoxolone derivative to afford a multisubstituted furan, whose substituents are derived from the alkynyl moiety (2-position), the imine (3- and 4-positions), and the 2-iodobenzoate moiety (5-position), along with an N-arylformamide under mild conditions. The 2-iodophenyl group of the furan product serves as a versatile handle for further transformations. A series of isotope-labeling experiments shed light on the bond reorganization process in this unusual condensation reaction, which includes cleavage of the C-C triple bond and fragmentation of the carboxylate moiety.

α-Palladation of imines as entry to dehydrogenative Heck reaction: aerobic oxidative cyclization of N-allylimines to pyrroles.

We report here a palladium(II)-catalyzed oxidative cyclization reaction of N-allylimines derived from methyl ketones, typically acetophenones, affording pyrrole derivatives at room temperature under oxygen atmosphere. The reaction likely proceeds through α-palladation of the imine followed by olefin migratory insertion and ß-hydride elimination, thus representing a new example of aerobic dehydrogenative Heck cyclization.

[Effects of H2 relaxin on airway remodeling and expression of cyclin D1 in a murine model of chronic asthma].

OBJECTIVE: To investigate the effects of H(2) Relaxin (Relaxin) on airway remodeling and the expression of cyclin D(1) in a murine model of chronic asthma. METHODS: Forty BALB/c mice were randomly divided into 4 groups:a normal control group, an asthma group, a vehicle control group and a relaxin treatment group, with 10 mice in each. The mice were sensitized and challenged with ovalbumin (OVA) to establish the chronic asthmatic model. The vehicle control group and the relaxin treatment group were subcutaneously injected with saline and relaxin (0.25 mg × kg(-1)× d(-1))respectively. Alteration of the airway inflammation and collagen deposition were observed by haematoxylin-eosin (HE) and Masson staining. Hydroxyproline in the lung was measured by enzyme linked immunosorbent assay (ELISA). The expression of α-smooth muscle actin (α-SMA) in lungs was evaluated by immunohistochemistry. The protein expression and the mRNA of cyclin D(1) were detected by Western blot and RT-PCR respectively. RESULTS: There were inflammatory cell infiltration, airway stenosis, bronchial smooth muscle hypertrophy and increased collagen deposition in the asthmatic group and the vehicle control group; but these changes were significantly ameliorated in the relaxin treatment group. The area of the α-SMA-stained smooth muscle layer in the asthmatic group and the vehicle control group was significantly greater than that in the control group (all P < 0.05), while administration of relaxin decreased the α-SMA immunostained area (all P < 0.05). The lung hydroxyproline content in the asthmatic and the vehicle groups [(0.68 ± 0.10) mg/g lung tissue, (0.67 ± 0.10) mg/g lung tissue] was significantly greater than that in the control group [(0.26 ± 0.05) mg/g lung tissue] (q = 16.61, 16.01 respectively, all P < 0.01). In contrast, treatment with relaxin significantly reduced the lung hydroxyproline content [(0.40 ± 0.06) mg/g lung tissue] compared with aforementioned 2 groups (q = 10.88, 10.26 respectively, all P < 0.05). The results of the Western blot analysis showed that the expression level of cyclin D(1) in the asthmatic and the vehicle groups [(1.38 ± 0.18), (1.50 ± 0.10)] was higher than that in the control group (0.38 ± 0.10) (q = 13.00, 14.65 respectively, all P < 0.05), while it was significantly decreased in the relaxin group (0.72 ± 0.13) (q = 8.51, 10.16 respectively, all P < 0.05). There were no differences in all of the parameters between the asthmatic group and the vehicle group (P > 0.05). CONCLUSION: Relaxin alleviated airway inflammation, airway smooth muscle thickening and airway remodelling in a murine model of chronic asthma, partially by down-regulating the expression level of cyclin D(1).

Strained small rings in gold-catalyzed rapid chemical transformations.

Gold-catalyzed reactions, which have been widely explored over the past several years, are powerful tools in organic synthesis to access complex molecular frameworks, and some corresponding excellent reviews have been reported. However, little attention has been paid to summarize the reactions of strained small-ring-containing molecules catalyzed by gold. This critical review mainly puts its emphasis on the recent progress in the field of gold-catalyzed transformations of cyclopropyl-, cyclopropenyl-, epoxy- and aziridinyl-containing molecules. The rapid construction of interesting building blocks in organic synthesis from strained small rings catalyzed by gold has been summarized in this review (106 references).