The interaction of different chlorine-based additives with swine manure during pyrolysis: Effects on biochar properties and heavy metal volatilization.

Poor properties and high concentrations of heavy metals are still major concerns of successful application of animal manure-derived biochar into the environment. This work thus proposed to add chlorine-based additives (Cl-additives, i.e., CaCl2, MgCl2, KCl, NaCl, and PVC, 50 g Cl/ kg) to improve biochar properties and enhance heavy metal volatilization during swine manure pyrolysis. The results showed that the addition of CaCl2 could improve the retention of carbon (C) by up to 13.1% during pyrolysis, whereas other Cl-additives had little effect on it. Moreover, CaCl2 could enhance the aromaticity of biochar, as indicated by lower H/C ratio than raw biochar. Pretreatment with CaCl2, MgCl2 and PVC reduced phosphorus (P) solubility but increased its bioavailability via the formation of chlorapatite (Ca5(PO4)3Cl). The CaCl2 was more effective for enhancing the volatilization efficiency of heavy metals than other Cl-additives, except for Pb that tended to react with the generated Ca5(PO4)3Cl to form more stable and less volatile Pb5(PO4)3Cl. However, high pyrolysis temperature (900℃) was essential for CaCl2 to simultaneously decrease the bioavailability of heavy metals. Our results indicated that co-pyrolysis of swine manure with CaCl2 is a promising strategy to increase C retention, P bioavailability, and volatilization of heavy metals, and, at higher temperature, reduce the bioavailability of biochar-born heavy metals.

Enhancement in ionic liquid tolerance of cellulase immobilized on PEGylated graphene oxide nanosheets: Application in saccharification of lignocellulose.

The objective of the present work was to improve ionic liquid (IL) tolerance of cellulase based on the exploration of functional nanoscale carriers for potential application in lignocellulosic biorefinery. PEGylated graphene oxide (GO) composite was successfully fabricated by chemical binding of 4-arm-PEG-NH2 and GO and applied to the immobilization of cellulase. The PEGylated GO-Cellulase retained 61% of the initial activity in 25% (w/v) 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) while free cellulase only retained 2%. The IL stability was enhanced more than 30 times. The relatively minor change in Km value (from 2.7 to 3.2mgmL(-1)) after the immobilization suggested that PEGylated GO-Cellulase was capable of closely mimicking the performance of free enzyme. After treating rice straw with [Bmim][Cl] and dilution to a final IL concentration of 15% (w/v), the slurry was directly hydrolyzed using PEGylated GO-Cellulase without IL removing and a high hydrolysis rate of 87% was achieved.

Electrochemical Synthesis and Magnetic Properties of [Cu9W6]: The Ultimate Member of the Quindecanuclear Octacyanometallate-Based Transition-Metal Cluster?

[Cu9W6], synthesized by the electrochemical method, may be the ultimate member of the quindecanuclear octacyanometallate-based transition-metal cluster. Its single-crystal structure and magnetic properties were characterized.

Electrochemical sensor based on nitrogen doped graphene: simultaneous determination of ascorbic acid, dopamine and uric acid.

Nitrogen doped graphene (NG) was prepared by thermally annealing graphite oxide and melamine mixture. After characterization by atomic force microscopy and X-ray photoelectron spectroscopy etc., the electrochemical sensor based on NG was constructed to simultaneously determine small biomolecules such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). Due to its unique structure and properties originating from nitrogen doping, NG shows highly electrocatalytic activity towards the oxidation of AA, DA and UA. The electrochemical sensor shows a wide linear response for AA, DA and UA in the concentration range of 5.0×10(-6) to 1.3×10(-3)M, 5.0×10(-7) to 1.7×10(-4)M and 1.0×10(-7) to 2.0×10(-5)M with detection limit of 2.2×10(-6)M, 2.5×10(-7)M and 4.5×10(-8)M at S/N=3, respectively. These results demonstrate that NG is a promising candidate of advanced electrode material in electrochemical sensing and other electrocatalytic applications.

Nanoconfinement effects: glucose oxidase reaction kinetics in nanofluidics.

Size-tunable nanofluidic devices coupled to an electrochemical detector have been designed and then used to study glucose oxidase (GOx) reaction kinetics confined in nanospaces. The devices are fabricated via a photochemical decomposition reaction, which forms nanochannels covered with carboxyl groups. The generated carboxyl groups enable us to chemically pattern biological molecules on the polymer surfaces via covalent bonding. With this approach, the activity of the immobilized biological molecules confined in nanospaces with different sizes has been investigated. GOx species are chemically immobilized on the surface of the nanochannels, catalyzing the oxidation of substrate glucose as it flows through the channels. The enzyme reaction product, hydrogen peroxide, passing through the nanochannels, reaches an electrochemical detector, giving rise to an increase in anodic current. This steady-state electrochemical current, which responds to various glucose concentrations, can be used to evaluate the GOx activity under confinement conditions. The results show significant nanoconfinement effects that are dependent on the channel size where the reaction occurs, demonstrating the importance of spatial confinement on the GOx reaction kinetics. The present approach provides an effective method for the study of enzyme activity and other bioassay systems, such as cell assays, drug discovery, and clinical diagnosis.

Catalyst-free synthesis of nitrogen-doped graphene via thermal annealing graphite oxide with melamine and its excellent electrocatalysis.

The electronic and chemical properties of graphene can be modulated by chemical doping foreign atoms and functional moieties. The general approach to the synthesis of nitrogen-doped graphene (NG), such as chemical vapor deposition (CVD) performed in gas phases, requires transitional metal catalysts which could contaminate the resultant products and thus affect their properties. In this paper, we propose a facile, catalyst-free thermal annealing approach for large-scale synthesis of NG using low-cost industrial material melamine as the nitrogen source. This approach can completely avoid the contamination of transition metal catalysts, and thus the intrinsic catalytic performance of pure NGs can be investigated. Detailed X-ray photoelectron spectrum analysis of the resultant products shows that the atomic percentage of nitrogen in doped graphene samples can be adjusted up to 10.1%. Such a high doping level has not been reported previously. High-resolution N1s spectra reveal that the as-made NG mainly contains pyridine-like nitrogen atoms. Electrochemical characterizations clearly demonstrate excellent electrocatalytic activity of NG toward the oxygen reduction reaction (ORR) in alkaline electrolytes, which is independent of nitrogen doping level. The present catalyst-free approach opens up the possibility for the synthesis of NG in gram-scale for electronic devices and cathodic materials for fuel cells and biosensors.

Determination of explosives using electrochemically reduced graphene.

A graphene-based electrochemical sensing platform for sensitive determination of explosive nitroaromatic compounds (NACs) was constructed by means of electrochemical reduction of graphene oxide (GO) on a glassy carbon electrode (GCE). The electrochemically reduced graphene (ER-GO) adhered strongly onto the GCE surface with a wrinkled morphology that showed a large active surface area. 2,4-Dinitrotoluene (2,4-DNT), as a model analyte, was detected by using stripping voltammetry, which gave a low detection limit of 42 nmol L(-1) (signal-to-noise ratio=3) and a wide linear range from 5.49×10(-7) to 1.1×10(-5) M. Further characterizations by electrochemistry, IR, and Raman spectra confirmed that the greatly improved electrochemical reduction signal of DNT on the ER-GO-modified GC electrode could be ascribed to the excellent electrocatalytic activity and high surface-area-to-volume ratio of graphene, and the strong π-π stacking interactions between 2,4-DNT and the graphene surface. Other explosive nitroaromatic compounds including 1,3-dinitrobenzene (1,3-DNB), 2,4,6-trinitrotoluene (TNT), and 1,3,5-trinitrobenzene (TNB) could also be detected on the ER-GO-modified GC electrode at the nM level. Experimental results showed that electrochemical reduction of GO on the GC electrode was a fast, simple, and controllable method for the construction of a graphene-modified electrode for sensing NACs and other sensing applications.

A facile approach to the synthesis of highly electroactive Pt nanoparticles on graphene as an anode catalyst for direct methanol fuel cells.

A one-step electrochemical approach to the synthesis of highly dispersed Pt nanoparticles on graphene has been proposed. The resultant Pt NPs@G nanocomposite shows higher electrocatalytic activity and long-term stability towards methanol electrooxidation than the Pt NPs@Vulcan.

[Analysis of Paeonia lactiflora by X-ray diffraction Fourier pattern method].

OBJECTIVE: To establish a new method for identification and analysis of traditional Chinese medicine root of herbaceous peony. METHODS: Powder X-ray diffraction Fourier fingerprint pattern was used. RESULTS: Experiments and analysis were carried out on 6 kinds of roots of traditional Chinese medicines herbaceous peony. The standard X-ray diffraction Fourier fingerprint pattern and characteristic diffraction peaks of Paeonia lactiflora were obtained. CONCLUSION: The results indicates this method can be used for the idetification of Paeonia lactiflora.

[Identification of Ligustrum lucidum Ait. by X-ray diffraction fourier pattern method].

OBJECTIVE: To set up a new identification and analysis method of Ligustrum lucidum Ait. METHODS: To get the extracts of Ligustrum lucidum Ait. using ethanol and chloroform ether as solvent and the extracts were identified by X-ray diffraction Fourier fingerprint spectra. RESULTS: Experiments and analysis were carried out on four samples. The standard X-ray diffraction Fourier fingerprint spectra and characteristic diffraction peaks were obtained. There were some differences among the spectra of the extracts, but the characteristic diffraction peaks were obvious. CONCLUSION: The experimental result indicated that X-ray diffraction Fourier fingerprint spectra can be used to identify and analyze Chinese traditional herb Ligustrum lucidum Ait.

[Identification of Magnolia biondii Pamp by X-Ray diffraction Fourier pattern method].

OBJECTIVE: To establish a new identification and analysis method of Magnolia biondii Pamp. METHODS: Powder X-Ray diffraction fourier fingerprint pattern method. RESULT: Experiment and analysis were carried out on five samples. The standard X-Ray diffraction Fourier fingerprint pattern method and characteristic diffraction peaks of Magnolia biondii Pamp were obtained. CONCLUSION: The method can be used for the identification of Magnolia biondii Pamp.