Prediction of adsorption performance of ZIF-67 for malachite green based on artificial neural network using L-BFGS algorithm.

Given the necessity and urgency in removing organic pollutants such as malachite green (MG) from the environment, it is vital to screen high-capacity adsorbents using artificial neural network (ANN) methods quickly and accurately. In this study, a series of ZIF-67 were synthesized, which adsorption properties for organic pollutants, especially MG, were systematically evaluated and determined as 241.720 mg g-1 (25 â„ƒ, 2 h). The adsorption process was more consistent with pseudo-second-order kinetics and Langmuir adsorption isotherm, which correlation coefficients were 0.995 and 0.997, respectively. The chemisorption mechanism was considered to be π-π stacking interaction between imidazole and aromatic ring. Then, a Python-based neural network model using the Limited-memory BFGS algorithm was constructed by collecting the crucial structural parameters of ZIF-67 and the experimental data of batch adsorption. The model, optimized extensively, outperformed similar Matlab-based ANN with a coefficient of determination of 0.9882 and mean square error of 0.0009 in predicting ZIF-67 adsorption of MG. Furthermore, the model demonstrated a good generalization ability in the predictive training of other organic pollutants. In brief, ANN was successfully separated from the Matlab platform, providing a robust framework for high-precision prediction of organic pollutants and guiding the synthesis of adsorbents.

Stability of glycosylated complexes loaded with Epigallocatechin 3-gallate (EGCG).

The application of Epigallocatechin-3-gallate (EGCG) in food industry was limited by its low stability in aqueous solutions and poor bioavailability in vivo. The novel EGCG glycosylated arachin nanoparticles (Ara-CMCS-EGCG) and EGCG glycosylated casein nanoparticles (Cas-CMCS-EGCG) were prepared to improve the stability and bioavailability of EGCG. The effect of different variables on the storage stability and the slow-release behavior of novel glycosylation complexes in nanoparticle background solution and artificial gastrointestinal fluid were investigated. The results showed that the DPPH scavenging activity of Ara-CMCS-EGCG and Cas-CMCS-EGCG were stable in temperature (25 âˆ¼ 70 °C). EGCG could enhance the crosslinking effect of molecular particles in glycosylation complexes solution. The glycosylated protein nanoparticles were stable to acid-base and enzymolysis in simulated gastrointestinal fluid. The release rate of EGCG in simulated intestinal fluid was higher than that in simulated gastric fluid. The glycosylated protein carrier can not only release EGCG slowly, but also significantly improve the stability and bioavailability of EGCG in simulated gastrointestinal fluid.

Preparation and characterization of high embedding efficiency epigallocatechin-3-gallate glycosylated nanocomposites.

Glycosylated protein nano encapsulation was an efficient encapsulation technology, but its embedding rate for EGCG was not high, and the research on the embedding mechanism was relatively weak. Based on this, this study compared the embedding effect of glycosylated peanut globulin and glycosylated casein on EGCG. The embedding mechanism of EGCG with glycosylated protein was discussed by ultraviolet, fluorescence, infrared and fluorescence microscopy. Results revealed that the highest encapsulation efficiency of EGCG was 93.89 ± 1.11%. The neutral pH value and 0.3 mg/mL EGCG addition amount were suitable for EGCG glycosylated nanocomposites. The hydrogen bond between EGCG hydroxyl group and tyrosine and tryptophan of glycosylated protein is mainly non covalent. The encapsulation effect of EGCG glycosylated nanocomposites could be quenched by changing the polar environment and spatial structure of the group. The fluorescence characteristic and dispersibility of EGCG glycosylated peanut globin were higher than EGCG glycosylated casein. This study might provide a theoretical basis for EGCG microencapsulation technology and EGCG application in tea beverage and liquid tea food systems.

Co-Based Nanosheets with Transitional Metal Doping for Oxygen Evolution Reaction.

Activated two-dimension (2D) materials are used in various applications as high-performance catalysts. Breaking the long-range order of the basal plane of 2D materials can highly promote catalytic activity by supplying more active sites. Here we developed a method to synthesize ultrathin MCoOx (M = V, Mn, Fe, Ni, Cu, Zn) amorphous nanosheets (ANSs). These Co-based ANSs show high oxygen evolution reaction (OER) activity in alkaline solution due to the broken long-range order and the presence of abundant low bonded O on the basal plane. The stable Fe1Co1Ox ANSs also show an overpotential of ca. 240 mV of achieving 10 mA/cm2 in OER, better than most reported transition metal-based electrocatalysts.

Green chemical synthesis of new chelating fiber and its mechanism for recovery gold from aqueous solution.

A novel environmentally-friendly polyacrylonitrile-2-amino-2-thiazoline chelating fiber (PANF-ATL) with good adsorption performance and thermal stability was synthesized in one step by nucleophilic addition reaction using water as a solvent. The optimum synthesis conditions for the chelating fibers are determined by controlling the synthesis temperature and the molar ratio of the reagents. The sulfur content and functional group capacity of the finally synthesized PANF-ATL were 3.82% and 1.19 mmol/g, respectively. PANF-ATL was characterized by elemental analysis, FTIR, TGA, SEM and XPS. Meanwhile, the adsorption characteristics and mechanism of PANF-ATL were evaluated. The Langmuir model and the pseudo-second-order model well described the adsorption of Au(Ⅲ) by PANF-ATL. The adsorption capacity of PANF-ATL obtained from Langmuir isotherm model towards Au(Ⅲ) was 130.58 mg/g (298 K). In addition, Au(Ⅲ) adsorbed on the fibers was completely eluted using a mixed solution of 4 mol/L HCl and 12% thiourea. It still has good adsorption performance after 5 adsorption-desorption cycles. Overall, PANF-ATL is a cost-effective adsorbent that can effectively adsorb Au(Ⅲ) in aqueous solution.

Green chemical method for the synthesis of chromogenic fiber and its application for the detection and extraction of Hg2+ and Cu2+ in environmental medium.

To advocate environment friendly detection idea, we adopted the green chemical method to synthesis the 1-(2 amino ethyl) piperidine functionalized polyacrylonitrile fiber (APF) and the chromogenic fiber 4-(2-pyridylazo) resorcinol (APF-PAR). The APF has high adsorption selectivity of Hg2+ and Cu2+, and the change of structure, surface morphology and thermo-stability before and after adsorption have been characterized by the infrared spectra, scanning electron microscope and thermogravimetric analysis. The APF achieved the adsorption equilibrium of Hg2+ just in 25 min and the adsorption capacity is 435.1 mg/g, while the adsorption equilibrium of Cu2+ costs 30 min and the adsorption capacity is 141.7 mg/g. The chromogenic fiber APF-PAR can recognize the Hg2+ and Cu2+ in 2 s, which benefits from the rapid mass transfer and small fluid resistance of the chelating PAN fiber. The color changed from orange to purplish red due to the variation of HOMO-LOMO energy gaps during the reaction which confirmed by the UV-vis absorption spectrum. It also has high selectivity and excellent adsorption performance, which provides more convenient, accurate, reliable and faster testing methods of Hg2+ and Cu2+ in environmental medium.

Preparation and characterization of casein-carrageenan conjugates and self-assembled microcapsules for encapsulation of red pigment from paprika.

This study aimed to investigate the optimum preparation condition of casein- carrageenan conjugate by ultrasonic Maillard dry treatment. The stable microcapsule was self-assembly prepared by the conjugates applied to protect red pigment from paprika. The optimum substrate ratio of Cas-Ca is 1:2, the reaction time and temperature were 24 h and 60 °C. Finally, the optimal degree of grafting reached 78.05%. Conjugation with carrageenan could further enhance solubility and emulsifying properties of casein. Glycosylation self-assembly nanoparticles were prepared with ultrasonic treatment, and the stability of the nanoparticles were excellent. Cas-Ca was effectively used to encapsulate PRP, and the PRP and PRP-microcapsule were stored for six days under the condition of high temperature, lighting, and food additives to observe the PRP retention rate. These results indicated the outstanding protective effect of microcapsule on PRP. Cas-Ca could be used as an effective carrier of PRP. They could effectively control release behavior in simulated gastrointestinal fluid. Cas-Ca microcapsule was disintegrated and released slowly within 3 h in simulated gastric fluid, but released rapidly within 1 h in intestinal environments, and the total release rate reached 76.6%.

Ruthenium-Catalyzed Ring-Opening Addition of Anilides to 7-Azabenzonorbornadienes: A Diastereoselective Route to Hydronaphthylamines.

The ruthenium(II)-catalyzed direct ring-opening reaction of 7-azabenzonorbornadienes with anilides via C-H activation to access hydronaphthylamines has been developed. The transformation proceeds with a high stereoselectivity to give cis-configuration products under redox-neutral conditions.

Research of a new metal chelating carrier preparation and papain immobilization.

A new type of magnetic metal chelating carrier (PCMM-IDA-Cu2+) was prepared for the immobilization of papain, using chitosan as raw material, nano Fe3O4 as magnetic material, SiO2 as porogen, iminodiacetic acid (IDA) as a chelating ligand, and binding with transition metal ion (Cu2+). The resulting products were well characterized by optical microscopy, scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The BBD (Box-Behnken Design) of RSM (Response Surface Methodology) was applied to analyze the optimum enzyme immobilization conditions. The results showed that the enzyme immobilization capacity was 94.18mg/g of PCMM-IDA-Cu2+, with 7.976U/mg of relative immobilized enzyme activity under the optimum conditions (pH6.73, 1.56mg enzyme/15.0mg carrier, 30.9°C), and the recovery of enzyme activity was reached 87.21%. Compared with the free papain, the immobilized papain displayed enhanced enzyme activity, superior enzymatic properties, good operational stability and reusability. It is worth mentioning that the novel carriers exhibited selectively biological adsorption capacity, and this technique is an alternative method for the immobilization of enzyme, making the process more efficient and economic.

Preparation of a novel chloromethylated polystyrene-2-mercapto-1,3,4-thiadiazole chelating resin and its adsorption properties and mechanism for separation and recovery of Hg(II) from aqueous solutions.

With an efficient methodology, a novel chloromethylated polystyrene-g-2-mercapto-1,3,4-thiadiazole chelating resin (MTR resin) was prepared via a one-step reaction. The structure of MTR resin was characterized by elements analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Meanwhile, the adsorption properties of the resin for Hg(II) were investigated by batch and column experiments. The results showed that the resin possessed much better adsorption capability for Hg(II) than for other metal ions. The statically and the dynamic saturated adsorption capacities were 343.8 mg/g and 475.1 mg/g. The adsorption kinetic and equilibrium data were well fitted to the second-order model and the Langmuir isotherm model, respectively. Desorption of mercury from the resin can be achieved using 30 mL of 2 mol/L HCl-5% thiourea solution with a desorption ratio of 92.3%. Compared with other absorbents, MTR resin was greatly conserve natural resources and reduce the cost.

Cobalt-Catalyzed Oxidant-Free Spirocycle Synthesis by Liberation of Hydrogen.

The first example of oxidant-free cobalt-catalyzed synthesis of five-membered spirocycles is reported from benzimidates and maleimides utilizing nitrobenzene as promoter. In contrast to previously known cobalt-catalyzed oxidative C-H functionalization reactions, this transformation occurs efficiently in the absence of oxidant and is accompanied by liberation of hydrogen. The spiro-lactams were readily achieved by the hydrolysis of as-prepared spirocyclic compounds. The Cp*Rh(III) catalyst shows poor reactivity.

[Effect of Raw Materials and Preparing Process on the Composition of Lime-Ash].

As the saying goes that "no ash, no glaze", lime-ash has been the core material widely used to prepare glaze in ancient China. Among all the lime-ashes, those made in Jingdezhen are the most influential and representative ones. Not only did lime-ash contribute greatly to the prosperity of porcelain making of Jingdezhen in Song, Yuan, Ming and Qing Dynasty, but also it has a complicated, rigorous and a touch of "mysterious" in its preparation process, technical principle and glaze mechanism. Therefore, the research of the lime-ash has been an important subject in exploring the "secret" of ancient Chinese porcelain production by Chinese and foreign researchers. In this paper, four representative firewood and two lime stones as the raw materials were collected for the comparative studies, and three kinds of lime-ash with different smolder times were collected from one of the only two traditional lime-ash workshops in Shou'an town nearby Jingdezhen urban area. The chemical composition and phase composition of the raw materials and lime-ash with different smolder times made in Jingdezhen were discussed by testing with the Energy Dispersive X Ray Fluorescence (EDXRF) and X-Ray Diffraction (XRD). The results showed that Fe(2)O(3), MnO contents reaches 1.41% and 1.52% respectively, but the P(2)O(5) content is just 0.54% of Langqi grass which is lower than other firewood that is not only benefited to form the characteristic of "Green in the white" in Jingdezhen traditional glaze, but also is favor to enhance the transparency of glaze and promote the coloration of traditional under-glazed color painted porcelain, such as the blue and white porcelain. The CaO content of grey lime stone is lower than that of the black lime stone with MgO content of 35.79%.This could be the main reason why the craftsmen prefer to use black lime stone to prepare lime-ash. In addition, the EDXRF results show that the K(2)O, P(2)O(5), MnO and Fe(2)O(3) contents have increased as the time of smoldering increases. In the meanwhile, the calcium carbonate (CaCO(3)) phase has also increased, but the calcium hydroxide (Ca(OH)(2)) phase has decreased. The study helps Jingdezhen porcelain "look like jade" and is also good to avoid the "thickness" of glaze when there is a certain amount of Ca(OH)(2) in glaze. So it could be concluded that the unique raw materials and smolder technology of the lime-ash which have provided the technical support for the development of lime-ash glaze are the unique features of ancient Jingdezhen ash glaze.

Optimization of conditions for Cu(II) adsorption on D151 resin from aqueous solutions using response surface methodology and its mechanism study.

An experimental study on the removal of Cu(II) from aqueous solutions by D151 resin was carried out in a batch system. The response surface methodology (RSM)-guided optimization indicated that the optimal adsorption conditions are: temperature of 35 °C, pH of 5.38, and initial Cu(II) concentration of 0.36 mg/mL, and the predicted adsorption capacity from the model reached 328.3 mg/g. At optimum adsorption conditions, the adsorption capacity of Cu(II) was 321.6 mg/g, which obtained from real experiments what were in close agreement with the predicted value. The adsorption isotherms data fitted the Langmuir model well, and the correlation coefficient has been evaluated. The calculation data of thermodynamic parameters (ΔG, ΔS, and ΔH) confirmed that the adsorption process was endothermic and spontaneous in nature. The desorption study revealed that Cu(II) can be effectively eluted by 1 mol/l HCl solution, and the recovery was 100%. Moreover, the characterization was undertaken by infrared (IR) spectroscopy.

Mechanisms and origins of switchable regioselectivity of palladium- and nickel-catalyzed allene hydrosilylation with N-heterocyclic carbene ligands: a theoretical study.

The mechanisms and origins for the Pd- and Ni-catalyzed regioselective hydrosilylation of allene have been investigated by means of density functional theory (DFT) calculations. The free-energy profiles of Pd- and Ni-catalyzed reactions with small and bulky N-heterocyclic carbene (NHC) ligands are calculated to determine the mechanism for regioselectivities. The calculation results show that different metals (Ni vs Pd) lead to regiochemical reversals for the hydrosilylation of allene. The allylsilane is the major product via palladium catalysis with small NHC ligand, while the vinylsilane is the major product via nickel catalysis with bulky NHC ligand. Both electronic and steric factors play a key role in the regioselectivities for the hydrosilylation of allene via Pd and Ni catalysts. The calculation results are in good agreement with observed regioselectivities and could provide insights into the design of new catalysts for the regioselectivity of hydrosilylation reactions.

Adsorption performance and mechanism for removal of Cd(II) from aqueous solutions by D001 cation-exchange resin.

The adsorption and desorption properties of D001 resin for Cd(II) has been investigated. Batch studies were carried out with various pH, contact time, temperature and initial concentrations, and then column studies were conducted. The results showed that the optimal adsorption condition was at pH value of 3.0 in HAc-NaAc medium. The resin exhibited a high Cd(II) uptake of 185.8 mg/g at 298 K. The apparent activation energy Ea is 5.05 kJ/mol and the sorption thermodynamic parameters are ΔH = 21.1 kJ/mol, ΔS = 0.122 kJ/(mol K) and ΔG298K = -15.3 kJ/mol, which indicated that the adsorption process was spontaneous and endothermic. Compared with the Freundlich isotherm, the sorption of Cd(II) obeys the Langmuir isotherm better. The Thomas model was delineated here to predict the breakthrough curves based on the experimental column study data. Furthermore, the resin could be regenerated through the desorption of the Cd(II) anions using 1 mol/L HCl solution and could be reused to adsorb again. The infrared spectroscopic technique was undertaken. Compared with other absorbents, D001 resin was relatively low cost and was effective in removing Cd(II) ions.

Adsorption behavior of Hg2+ in aqueous solutions on a novel chelating cross-linked chitosan microsphere.

In this study, cross-linked chitosan microspheres (CCTS) was synthesized from chitosan and epichlorohydrin (ECH), then, 2-(chloromethyl) benzimidazole (CBM) was introduced to modify CCTS as the ligand. The resulting CBM-chitosan was characterized by EA, FTIR and TGA, and tested for metal adsorption. Results showed that CBM-chitosan has a relatively high selectivity toward Hg(2+). Equilibrium data were fitted well with Langmuir isotherms with the maximum adsorption capacity of 257.8 mg/g for Hg(2+). Both kinetics and thermodynamic parameters of the adsorption process were obtained. The data indicated that adsorption process was exothermic spontaneous reaction and kinetically proceeded according to Second-order kinetics model. CBM-chitosan can be eluted effectively using 1.0 mol/L HCl solution and it has a potential use for separation and preconcentration of Hg(2+) ions from contaminated natural waters.

Preparation and application of acrylic acid grafted polytetrafluoroethylene fiber as a weak acid cation exchanger for adsorption of Er(III).

In this work, a weakly acidic ion exchange fiber (PTFE-g-AA) has been prepared by 60Co irradiation grafting with acrylic acid (AA) onto the polytetrafluoroethylene (PTFE) fiber. The grafted fiber was characterized by FTIR, SEM and TGA technique. The exchange capacity of the PTFE-g-AA fiber is 3.87 mmol/g. The adsorbent material was employed for Er(III) uptaking by batch and column experiments. Kinetics studies showed that the adsorption process obeyed pseudo-second-order kinetics. The adsorption isotherms followed both the Freundlich model and Langmuir model. The maximum adsorption capacity of the PTFE-g-AA fiber for Er(III) was evaluated to be 142.0mg/g for the Langmuir model. It was found that 0.75 M HCl-0.25 M NaCl solution provided effectiveness of the desorption of Er(III) from the PTFE-g-AA fiber. Various thermodynamic parameters such as standard enthalpy (DeltaH(0)), standard entropy (DeltaS(0)) and standard free energy (DeltaG(0)) were evaluated. The adsorption of Er(III) on the PTFE-g-AA fiber was found to be endothermic in nature. The Thomas model was successfully applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design.