Hui Luo

Synthesis of 3D nitrogen-doped graphene/Fe3O4 by a metal ion induced self-assembly process for high-performance Li-ion batteries

We demonstrate the fabrication of three-dimensional nitrogen-doped graphene (3D N–G)/nanoparticle anode architectures consisting of 3D N–G networks and Fe3O4 nanoparticles. In such a hybrid structure, the N–G networks act as a buffer matrix to accommodate the volume change of Fe3O4, and the interconnected N–G sheets effectively prevent the aggregation of nanoparticles during cycling, both of which enable the structural integrity and electrochemical stabilization of such composite electrodes. Furthermore, the as-obtained porous nitrogen-doped hybrid materials promote efficient transport of both lithium ions and electrons upon charging/discharging, and also provide defect sites as Li+ active sites on the surface of N–G sheets. As a result, the hybrids exhibit much-improved lithium storage performance.

Magnetic Fe3O4-GO nanocomposites as highly efficient Fenton-like catalyst for the degradation of dyes

In this work, a new and highly degradation efficiency Fenton-like catalyst based on Fe3O4 magnetic nanoparticles decorated with graphene oxide (GO) was successfully prepared and used to remove Rhodamine B (RhB) from aqueous solution. The Fe3O4-GO nanocomposites were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectrometer (FTIR), respectively. The effects of catalyst dosage, H2O2 adding amount and pH on the degradation rate of RhB were also investigated. When 0.2 g/L of Fe3O4-GO was introduced to RhB solution (10 mg/l, 100 ml), about 95% RhB was degraded within 60 min under optimisation condition. Comparing with bare Fe3O4 nanoparticles, the degradation rate of Fe3O4-GO nanocomposites was much higher at the same reaction condition. Moreover, the Fe3O4-GO nanocomposites were demonstrated to have excellent reusability and could be easily separated from the aqueous solution by an external magnetic field. Therefore, the Fenton-like catalyst is potentially usable for degrading dyes in the field of environmental protection.

Synthesis of Polyaniline/Graphene Composites and Its Application in Detecting Heavy Metal Ions

Polyaniline/graphene nanocomposite (PANI/G) was synthesized by an in situ polymerization procedure. The microstructure of PANI/G was characterized to be a mixture of PANI nanowires and graphene sheets by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Energy Dispersive X-Ray Fluoresence Spectrometer (EDX). PANI/G was used to modify glassy carbon electrodes to detect heavy metal ions in aqueous phase by the electrochemical methods. To make a contrast, Polyaniline (PANI) modified glassy-carbon electrode was also used to detect the mixed heavy metal ions including Cd2+, Pb2+, Cu2+ by Anodic Stripping Voltammetry (ASV). Results showed that PANI/G exhibiting higher sensitivity in detecting heavy metal ions than PANI and showing a great selectivity towards Pb2+. Then the electrochemical behavior in detecting Pb2+ by PANI/G was investigated. The detection limit for Pb2+ was 10-8mol/L, being lower than that of national sanitary standard for drinking water.

Surface Modification of Acrylonitrile Fibers and Membrane by Nitrilase from Escherichia Coli BL21 (DE3)/pET-Nit

The surface of polyacrylonitrile fibers and membrane were modified by nitrilase from Escherichia coli BL21 (DE3)/pET-Nit. Escherichia coli BL21(DE3)/pET-Nit was able to convert nitrile groups on PAN fibers and membrane to corresponding carboxylic acid as indicated by X-ray photoelectron spectroscopy (XPS). An increase of O/C atomic ratio on the fiber and membrane surface showed an increase in hydrophilicity and fabric-dyeing efficiency. Strength of treated fiber decreased by only 1.17%, because only surfacial nitrile groups of acrylic fibers were hydrolyzed by E.coli BL21(DE3)/pET-Nit.

Rapid Gene Cloning, Overexpression and Characterization of a Thermophilic Catalase in E. coli

A thermophilic catalase-encoding gene was rapidly obtained by means a PCR-based protocol with the genomic DNA mixture from compost culture as the template. The open reading frame of this gene is composed of 2208 base pairs, sharing 92.5% homology with the reported Bacillus stearothermophilus gene (NCBI genbank accession No. AB020234. 1). A prokaryotic expression plasmid pET-CATHis was constructed for the gene expression, and two recombinant E. coli, BL21(DE3)/pET-CATHis and BL21(DE3)pLysS/pET-CATHis were finally obtained. After culture optimization, the highest activities for these two strains in shaking flask culture were 74.3 U/ml and 1055.3 U/ml, respectively. The 6 His-tagged recombinant catalase was then purified by using immobilized metal affinity chromatography, and the properties of the purified protein were finally characterized.

Study on Optimization of Fermentation Condition for Nitrilase-Producer Escherichia Coli BL21 (DE3)/pET-Nit

The paper concentrated on the optimization of the recombinant strain BL21 (DE3)-PE7-Nit. The component of culture medium and the culture conditions were optimized. The optimized medium was: yeast extract 10 g/l, L-glutamate sodium 8 g/l, MgSO4.7H2O 0.7 g/l, Isopropyl-β-D-thiogalactopyranoside 0.3 mmol/L, potassium hydrogen phosphate 0.5 g / L, phosphate Potassium 0.5 g / L and the culture condition was: initial pH 7.0, inoculum 2%. The result showed that the activity of nitrilase prepared with these conditions increased by 130.37 % through optimization.

Construction of Recombinant E.coli Expressing a Thermophilic Catalase and its Application in H2O2 Wastewater Treatment

The recombinant plasmid pETac-CATHis with tac promoter was constructed for the constitutive expression of a thermophilic catalase in E.coli. And the effects of cultivation conditions of two recombinant strains, BL21(DE3)/pETac-CATHis and BL21(DE3)pLysS/pETac-CATHis, such as initial pH, cultivation temperature, cultivation time, and loading volume on catalase activity were investigated. The optimal cultivation conditions were: the initial pH 7.0, cultivation temperature 37°C, cultivation time 12 hours, and loading volume 25mL in 100mL flask. Under the optimal cultivation condition, the highest catalase activities of the two recombinant strains were 291.7 U/mL and 349.5 U/mL, respectively. After adding catalase, H2O2 in simulation H2O2 wastewater containing phenol was decomposed completely very quickly. Declining of catalase activity was detected with enhancing the phenol concentration, probably because the phenol might be a kind of competitive inhibitor for catalase.

Study on treating avermectin wastewater with SBR technique

The avermectin wastewater was treated with SBR technique. This paper was focused mainly on the removal rate of COD and change of ammonia nitrogen of influent and effluent. At the stable phase of SBR reactor operation, the removal rate of COD could be about 75% when the influent volume load was 1.01 kg/(m3 d), and the effluent COD was below 300 mg/L. Temperature had a great impact on the effect of ammonia nitrogen removal. When the temperature was below 10 °C, nitration was inhibited obviously, while the temperature raised to 25 °C, the effluent ammonia nitrogen could be below 10 mg/L, the removal rate reached around 95%.

Research for Treating Avermectin Wastewater with UASB Technique

The avermectin wastewater was treated with UASB technique. The paper was focused mainly on the removal rate of COD and the change of ammonia nitrogen of influent and effluent wastewater in the first running stage. At the stable phase of anaerobic operation, the removal rate of COD could be stabilized at 85% when the influent volume load was 9.21 kg/(m3•d), and the effluent COD was about 1400 mg/L. As for ammonia nitrogen concentration of influent and effluent wastewater, in the first 50 days, the former was larger than the latter, after then, it was opposite. In the condition of same volume load but different hydraulic retention time (COD concentration of influent being different), COD removal rate kept almost the same. In the second running stage, the influent COD volume load reached 9.21 kg/(m3•d) at the 16th day, with the COD removal rate being around 87%.

Adsorption of Methylene Blue onto Secondary Expanded Graphite

A secondary oxidation and expansion of graphite process resulted in a specific surface area enhanced material, which could be used in methylene blue (MB) adsorption in industry, due to the low running cost and mass production. The morphology of the samples was investigated using scanning electron microscopy, and the structures vary from the expansion level. It was found that with a pH value about 9, the sample exhibited better adsorption property toward MB after re-expansion. The adsorption capability of MB adsorbed on unit mass of the secondary expanded graphite turned out to be 120mg/g. The considerable adsorption capability could be further enhanced through a multiple expansion process.