Yan Huang

A study on synthesis and properties of Fe3O4 nanoparticles by solvothermal method

Magnetic nanoparticles (Fe3O4) were synthesized by the solvothermal method using FeCl3 · 6H2O and ethylene glycol as a reactant. Powder X-ray diffraction, FT-IR, TEM, SEM, and VSM were used to characterize the magnetic particles. The reacting factors, such as reacting time, the concentration of iron source and surfactant, especially the effect of NaAc · 3H2O, were studied. The results indicated that NaAc · 3H2O plays the role not only as a dispersant but also a structure-directing agent. The synthesized Fe3O4 particles showed excellent magnetic property, which made them have potential for application in magnetic nanodevices and biomedicine.

Cagelike mesoporous silica encapsulated with microcapsules for immobilized laccase and 2, 4-DCP degradation

In this study, cage-like mesoporous silica was used as the carrier to immobilize laccase by a physical approach, followed by encapsulating with chitosan/alginate microcapsule membranes to form microcapsules of immobilized laccase based on layer-by-layer technology. The relationship between laccase activity recovery/leakage rate and the coating thickness was simultaneously investigated. Because the microcapsule layers have a substantial network of pores, they act as semipermeable membranes, while the laccase immobilized inside the microcapsules acts as a processing plant for degradation of 2,4-dichlorophenol. The microcapsules of immobilized laccase were able to degrade 2,4-dichlorophenol within a wide range of 2,4-dichlorophenol concentration, temperature and pH, with mean degradation rate around 62%. Under the optimal conditions, the thermal stability and reusability of immobilized laccase were shown to be improved significantly, as the removal rate and degradation rate remained over 40.2% and 33.8% respectively after 6cycles of operation. Using mass spectrometry (MS) and nuclear magnetic resonance (NMR), diisobutyl phthalate and dibutyl phthalate were identified as the products of 2,4-dichlorophenol degradation by the microcapsules of immobilized laccase and laccase immobilized by a physical approach, respectively, further demonstrating the degradation mechanism of 2,4-dichlorophenol by microcapsule-immobilized laccase.

Preparation and Biological Applications of Graphene Oxide Functionalized Water-Based Magnetic Fluids

Magnetic fluids (MFs) with good dispersion were prepared by speed-controlled co-precipitation method, using polyethylene glycol (PEG-4000) as dispersing agent. To functionalize the MFs with graphene oxide (GO), highly dispersed nano-magnetic particles (NMPs) were firstly prepared by low-temperature freeze-drying technique. 3-aminopropyltriethoxysilane (APTES) was then attached on the surface of NMPs to form amino functionalized NMPs. GO was finally assembled with amino functionalized NMPs, to prepare GO functionalized MFs (GO-NMPs) by electrostatic adsorption. The obtained GO-NMPs were then characterized by FTIR, XRD, TEM, SEM and VSM. Meanwhile, mice were in vivo used as animal model to study biological application of 99Tcm labeled GO-NMPs, suggesting that the targeted functionalized magnetic particles had higher magnetic response effect under pulsed magnetic gradient field.

Comparative Studies on Enzyme Activity of Immobilized Horseradish Peroxidase in Silica Nanomaterials with Three Different Shapes and Methoxychlor Degradation of Vesicle-Like Mesoporous SiO2 as Carrier

In the present work, three differently shaped mesoporous silica nanoparticles, spherical nano-SiO2, tubular mesoporous SiO2 and vesicle-like mesoporous SiO2 (VSL), were prepared and used to immobilize Horse radish peroxidase (HRP), and their enzymes activity was also evaluated. It was found that the VSL immobilized HRP displayed higher specific activity than free enzyme and other two differently shaped silica immobilized HRP. After immobilization, the thermal stability, pH tolerance resistance and storage stability on vesicle-like SiO2 were studied as well. In addition, the kinetic constants Km and Vmax for HRP were significantly altered by immobilization. The affinity for HRP towards its substrate increased (with decreasing Km), leading to enhanced catalytic efficiency (with increased Vmax). Moreover, the reusability for degradation of methoxychlor (MXC) by VSL immobilized enzyme was studied and its degradation products were detected by GC-MS and NMR analysis.

A Novel Layered Anchoring Structure Immobilized Cellulase via Covalent Binding of Cellulase on MNPs Anchored by LDHs

In this study, Fe3O4 nanoparticles were first synthesized by co-precipitation method and then layered double hydroxides (LDHs) nanosheets were anchored onto Fe3O4 via an in-situ growth method to prepare LDHs@Fe3O4 carrier. The obtained magnets and LDHs@Fe3O4 carrier were characterized by XRD, FT-IR, N2 adsorption, HRSEM and HRTEM respectively. Using glutaraldehyde as a coupling agent, cellulase was immobilized onto this magnetic carrier by covalent binding. The effects of various parameters on enzyme activity of LDHs@Fe3O4 immobilized cellulase, including cellulase concentration, glutaraldehyde concentration, crosslinking time, pH, cellulase concentration, immobilization time and temperature were discussed in detailed. Moreover, thermal stability and operating stability of the immobilized cellulase were studied, the loaded amount of cellulase was measured, and the degradation performance of methoxychlor (MXC) by layered anchoring structure immobilized cellulase was evaluated.

A Novel Ship-in-Bottle Type Immobilized HRP via Co-adsorption of Super Paramagnets and HRP into Silica Hollow Fiber

In this paper, two type silica hollow fibers were synthesized through a soft template and hard template directing route respectively, and the super paramagnets was synthesized by thermal decomposition. The obtained silica hollow fiber and super paramagnets were characterized by XRD, N2 adsorption, SEM, TEM, EDS and XPS respectively. The ship-in-bottle type immobilized horseradish peroxidase (HRP) was assembled by co-adsorption of super paramagnets and HRP into the pore channel of silica hollow fiber in reverse microemulsion media. The effects of various parameters on enzyme activity of ship-in-bottle type immobilized HRP, including morphology, water content (ω0), super paramagnets concentration, HRP concentration, adsorption time, pH, crosslinking time and glutaraldehyde concentration were discussed in detailed. Moreover, the degradation performance of dichlorodiphenyltrichloroethane (DDT) by HRP immobilized on silica hollow fiber and spherical nano-silica was evaluated.Graphical AbstractThe ship-in-bottle type immobilized HRP have been prepared by uniformly co-adsorption of super paramagnets and HRP into the pore channel of silica hollow fiber with high enzyme activity, as evidenced by HRTEM characterization, which can be employed to degrade DDT to low toxic organic compound with low molecular weight.

Preparation of Magnetic Pearlescent Pigment Mica/Fe3O4 by Thermally Decomposing Ferric Formate Composite Containing Hydrazine

AbstractMica/Fe3O4 pearlescent pigment was synthesized via thermal decomposition of ferric formate composite containing hydrazine (composite salts), which was deposited on the surface of mica. The obtained product showed good dispersity, magnetic property and special black luster. The effects of pH value, sodium hydroxide concentration, molar ratio, stirring speed and temperature on composited salt coating rate and smooth on the mica surface were investigated. The optimum parameters were obtained including the pH value, the concentration of sodium hydroxide, the molar ratio of formic acid to Fe3+, the velocity of magnetic stirring, calcination temperature and time. It was also found that coating properties such as smoothness, compactness and color deepness were influenced by different pH, temperatures, sodium hydroxide concentration and so on. The products were characterized by X-ray diffraction, high resolution scan electron microscopy, vibrating sample magnetometer, color measurement and element analysis. The results indicates that a concentration 1.0xa0mol/L, a pH value between 4.0 and 4.5, a formic acid/Fe3+ ratiou2009=u20093, a stirring speed at 180xa0rpm/min at room temperature are the best conditions to obtain a good coating performance and a suitable pearly luster effect.Graphical AbstractPearlescent pigment was prepared by the decomposition of composite salt on micron surface. Different parameter were evaluated separately to obtain suitable products having a significant pearly luster effect. The best results were observed when sodium hydroxide concentration is 1.0xa0mol/L, the value of pH is between 4.0 and 4.5, the molar ratio [formic acid]/[Fe3+] is 3:1 and the stirring speed is 180xa0rpm/min and the products is prepared under room temperature.n

Laccase immobilized on mesoporous SiO2 and its use for degradation of chlorophenol pesticides

In this paper, mesoporous silica with large specific surface area was used to immobilize laccase by the glutaraldehyde cross-linking method, and after screening and optimization experiments, the best enzyme immobilization process conditions were found (25°C, pH 5.4, 4% glutaraldehyde and 0.2 g/L laccase, treatment time 6 h). After that, the removal and degradation ratio of 2,4-dichlorophenol (abbreviated as DCP) under different conditions were also studied. After the degradation process was performed for 6 h at 30°C, pH 5.4, and DCP initial concentration of 50 mg/L in the presence of 0.1 g of immobilized laccase, the removal ratio and the degradation ratio were 42.28 and 15.93%, respectively. Compared with free laccase, the reusability of immobilized laccase is significantly improved.

USPIO assisting degradation of MXC by host/guest-type immobilized laccase in AOT reverse micelle system.

The laccase and ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) have been assembled inside the tubular mesoporous silica via co-adsorption technology to prepare host/guest-type immobilized laccase, which is applied to degrade methoxychlor (MXC) in aqueous and reverse micelle environments. The effects of various parameters on degradation of MXC were studied. Under the optimum conditions, the degradation rate could reach maximum value of 45.6xa0% and remain at 20.8xa0% after seven cycles. Moreover, the addition of small molecular compound 2, 2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) to the system could greatly improve the degradation efficiency. The MXC degradation process is a first-order reaction, and the activation energy of MXC degradation catalyzed by immobilized laccase (41.46xa0kJxa0mol−1) is relatively lower than that catalyzed by free laccase (44.91xa0kJxa0mol−1). Based on the degradation products measured by gas chromatograph-mass spectrometer (GC-MS) and nuclear magnetic resonance (NMR), the degradation mechanism of MXC has also been proposed.

Hydrothermal synthesis, structure, and properties of a novel 2D stair-like zinc coordination polymer with benzene–1,2–diosylacetate

The hydrothermal reaction of Zn(CH3COOH)2 6H2O with benzene-1,2-dioxyacetic acid (H2BDOA) and 1,4-bis(imidazol-1-yl)butane (Bimb) yields a novel 2D zinc coordination polymer, [Zn(BDOA)(Bimb)] 3H2On, in which the Bimb ligands link the 1D Zn-BDOA chains into two kinds of 1D ladder-like structure to construct a 2D stair-like structure. It latter exhibits intense blue photoluminescence upon photoexcitation.