Wenbing Li

Degradation of p-Nitrophenol using magnetic Fe0/Fe3O4/Coke composite as a heterogeneous Fenton-like catalyst

A Coke supported Fe3O4 and Fe0 composite (Fe0/Fe3O4/Coke) was prepared for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the Fenton degradation of p-Nitrophenol (p-NP). A four factor Box-Behnken design (BBD) coupled with response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely Fe0/Fe3O4/Coke dosage, reaction temperature, initial pH and H2O2 concentration, on the removal efficiency of p-NP. A significant quadratic model (p-value<0.0001, R2=0.9952) was derived using analysis of variance (ANOVA). Optimum conditions were determined to be 1.3g/L catalyst, 32°C, pH3.1 and 11.3mM H2O2. 100% of p-NP (100mg/L) conversion and 81% of COD removal were achieved after 120min of reaction time, respectively, under the optimum conditions, which agreed well with the modeling prediction. The recyclability of Fe0/Fe3O4/Coke was also investigated after three successive runs, in which p-NP degradation performances showed a slight difference with the first oxidation cycle with an acceptable iron leaching. Moreover, according to the main intermediate products identified by gas chromatography-mass spectrometry (GC-MS), a possible pathway of p-NP degradation was proposed based on hydrogen radicals ([H]) or hydroxyl radicals (•OH) mechanism.

Heterogeneous Fenton degradation of Orange II by immobilization of Fe3O4 nanoparticles onto Al-Fe pillared bentonite

A novel catalyst, Fe3O4 nanoparticle decorated Al-Fe pillared bentonite (Fe3O4/Al-Fe-P-B), was prepared by in situ precipitation oxidization method. The catalyst was characterized by SEM, XRD and Raman spectroscopy. The Fe3O4 nanoparticles mainly exist on the surface or enter into the pore of bentonite, with better dispersing and less coaggregation. The catalytic activity of Fe3O4/Al-Fe-P-B was investigated in the degradation of Orange II (OII) by heterogeneous Fenton-like process. The effects of initial concentration of hydrogen peroxide, catalyst loading, temperature and initial pH on the degradation of OII were investigated. The Fe3O4/Al-Fe-P-B showed higher degradation efficiency of OII than bare Fe3O4 or Al-Fe-P-B in the degradation experiment. The enhanced catalytic activity of Fe3O4/Al-Fe-P-B in heterogeneous Fenton system was due to the synergistic effect between Al-Fe-P-B and Fe3O4. The novel catalyst can achieve solid-liquid separation easily by sample magnetic separation and has a good reusability and stability.

Synthesis and characterization of biomimetic Fe3O4/coke magnetic nanoparticles composite material

A composite material (Fe3O4/Coke) using coke supported Fe3O4 magnetic nanoparticles was successfully prepared via an in-situ chemical oxidation precipitation method and characterized by SEM, XRD, Raman, and FTIR. The results showed that the Fe3O4 nanoparticles existed steadily on the surface of coke, with better dispersing and smaller particle size. The catalytic ability of Fe3O4/Coke were investigatied by degrading p-nitrophenol (P-NP). The results showed that the apparent rate constant for the P-NP at 1.0 g·L−1 catalyst, 30 mmol·L−1 H2O2, pH=3.0, 30 °C and the best ratio of Coke/Fe3O4 0.6, was evaluated to be 0.027 min–1, the removal rate of CODCr was 75.47%, and the dissolubility of Fe was 2.42 mg·L–1. Compared with pure Fe3O4, the catalytic ability of Fe3O4/Coke in the presence of H2O2 was greatly enhanced. And Fe3O4/Coke was a green and environmental catalyst with high catalytic activity, showing a good chemical stability and reusability.

Electrospun 4th-Generation Solid Dispersions of Poorly Water-Soluble Drug Utilizing Two Different Processes

Different from traditional solid dispersion (SD) for improving the dissolution rates of poorly water-soluble drugs, the upgraded 4th SD was developed to furnish a drug sustained-release profile. In this work, two different kinds of 4th SDs were fabricated using two electrospinning processes. One is a ternary SD (nanofibers F2) that consisted of ethyl cellulose (EC), polyethylene glycol 1000 (PEG), and tamoxifen citrate (TAM) from a modified coaxial process, and the other is a binary SD (nanofibers F1) which is comprised of EC and TAM from a single-fluid blending process. Scanning electronic microscopic observations demonstrated that F2 (  nm) showed a better quality than F1 (  nm) in terms of size and size distribution although both of them had a smooth surface morphology and a cross section. X-ray diffraction patterns verified that both SDs were amorphous nanocomposites owing to the favorable secondary interactions among these components, as suggested from the results of FTIR. In vitro dissolution experiments indicated that F2 could furnish an improved drug sustained-release characteristics compared to F1, exhausting all the contained TAM and having weaker leveling-off late release. The molecular behaviors of drug sustained-release from the binary 4th SD were suggested. The protocols reported here paved an alternative way for developing novel functional nanomaterials for effective delivery of poorly water-soluble drugs.

Visible light induced photocatalytic degradation of rhodamine B by magnetic bentonite.

The photocatalytic activity of magnetic bentonite, Fe3O4 nanoparticles decorated Al-pillared bentonite (Fe3O4/Al-B), for the degradation of rhodamine B (RhB) in the presence of H2O2 under visible light (VL) was evaluated. The effects of different reaction parameters such as catalyst dose, dye concentration and externally added H2O2 were also investigated. The magnetic bentonite showed good photocatalytic activity, magnetic separability and stability for repeated use. More than 95% of 40 mg/L RhB was converted within 3 h under VL with a catalyst dose of 0.5 g/L. Suitable mechanisms have been proposed to account for the photocatalytic activities in the presence and absence of H2O2. The efficiency of H2O2 in VL process was much higher than that of the dark process. Results obtained in the current study may be useful to develop a suitable photocatalyst for photocatalytic remediation of different water contaminants including organic dyes.

Synthesis of magnetically modified Fe-Al pillared bentonite and heterogeneous Fenton-like degradation of orange II

Magnetically modified Fe-Al pillared bentonite (Fe3O4/Fe-Al-Bent) was prepared via chemical co-precipitation method and characterized by powder X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). A series of experiments were carried out to investigate the degradation of Orange II by the obtained heterogeneous catalysts in the presence of H2O2. The experimental result indicated that the synthetic materials had a high catalytic activity and good reusability.

Optimization of conditions for schizophyllan production in submerged culture of schizophyllum commune

The effects of oleic acid, folic acid, citric acid, α-naphthalene acetic acid, L-glutamic acid, carboxymethylce-lluose, and Tween 80 at different concentrations on the schizophyllan production and mycelial growth in a submerged culture of S. commune CGMCC 5.113 at pH 6.5 and 26 °C were determined. The highest production of schizophyllan and biomass in submerged culture were 13.95 g/l and 27.56 g/l under the optimal conditions (oleic acid 0.1% (v/v), folic acid 1.5 mg/l, citric acid 0.2% (m/v), α-NAA 0.2 mg/l, L-glutamic acid 1.0 mg/l, CMC 0.8% (m/v), and Tween 80 5ml/l), respectively. The results of bioreactor fermentation also show that the optimal conditions enhanced schizophyllan production (13.68 g/l) and biomass (26.01 g/l) by S. commune in a 5–l fermentor.

Tunable drug release from nanofibers coated with blank cellulose acetate layers fabricated using tri-axial electrospinning

In this study, novel core-shell nanostructures were fabricated through a modified triaxial electrospinning process. These comprised a drug-protein nanocomposite coated with a thin cellulose acetate (CA) shell. They were generated through the simultaneous treatment of an outer solvent, an unelectrospinnable middle fluid, and an electrospinnable core solution in triaxial electrospinning. SEM and TEM results revealed that the core-shell nanofibers had linear and cylindrical morphologies with a diameter from 0.66 to 0.87 μm, and distinct core-shell structures with a shell thickness from 1.8 to 11.6 nm. The presence of a CA coating eliminated the initial burst release of ibuprofen seen from a monolithic drug-protein composite, and allowed us to precisely manipulate the drug release (for a 90% percentage) over a time period from 23.5 to 43.9 h in a tunable manner. Mathematical relationships between the processing conditions, the nanostructures produced, and their functional performance were elucidated.

Teaching Materials for Engineering Education in High School from the Increase of Working Fluids in Electrospinning

Scientific innovation is often reflected in the engineering processes. On the contrary, the engineering processes hidden in advanced technologies can provide many vivid teaching materials for effective innovation and engineering educations to the college students in high school. In this paper, we conclude the advancement of electrospinning processes, which is fast developed from one-fluid blending process two decades before to two-fluid coaxial electrospinning, and now develops three-fluid tri-axial electrospinning. The increase of working fluids in electrospinning is useful for college students to provoke their interests in advanced nanotechnologies. Meanwhile, the increase of working fluids in electrospinning is also excellent teaching materials for the students to build linkages between their previous knowledge and new technologies, so deepening their comprehensions on them. What is more, the increase of working fluids in electrospinning is excellent teaching materials for the students to learn how to implement innovations all by themselves,such as engineering design innovation, analogical innovation, and innovation of analytical methods. Keywords—Teaching materials; Innovation education; College students; Electrospinning; Working fluids

Properties of magnetite nanoparticles produced by magnetotactic bacteria

The magnetic nanoparticles (magnetite) were prepared through the fermentation of the Magnetospirillum strain WM-1 newly isolated by our group. The samples were characterized by TEM, SAED, XRD, rock magnetic analysis, and Mössbauer spectroscopy. TEM and SAED measurements showed that the magnetosomes formed by strain WM-1 were single crystallites of high perfection with a cubic spinel structure of magnetite. X-ray measurements also fitted very well with standard Fe3O4 reflections with an inverse spinel structure of the magnetite core. The size of crystal as calculated by the Debye-Scherrer’s equation was approximately 55 nm. Rock magnetic analysis showed WM-1 synthesized single-domain magnetite magnetosomes, which were arranged in the form of linear chain. The high delta ratio ((δFC / δZFC = 4) supported the criteria of Moskowitz test that there were intact magnetosomes chains in cells. The Verwey transition occurred at 105 K that closed to stoochiometric magnetite in composition. These observations provided useful insights into the biomineralization of magnetosomes and properties of M. WM-1 and potential application of biogenic magnetite in biomaterials and biomagnetism.