Yingqing Zhan

Novel polyvinylidene fluoride nanofiltration membrane blended with functionalized halloysite nanotubes for dye and heavy metal ions removal.

Membrane separation is an effective method for the removal of hazardous materials from wastewater. Halloysite nanotubes (HNTs) were functionalized with 3-aminopropyltriethoxysilane (APTES), and novel polyvinylidene fluoride (PVDF) nanofiltration membranes were prepared by blending with various concentrations of APTES grafted HNTs (A-HNTs). The morphology structure of the membranes were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). The contact angle (CA), pure water flux (PWF) and antifouling capacity of membranes were investigated in detail. In addition, the separation performance of membranes were reflected by the removal of dye and heavy metal ions in simulated wastewater. The results revealed that the hydrophilicity of A-HNTs blended PVDF membrane (A-HNTs@PVDF) was enhanced significantly. Owing to the electrostatic interaction between membrane surface and dye molecules, the dye rejection ratio of 3% A-HNTs@PVDF membrane reached 94.9%. The heavy metal ions rejection ratio and adsorption capacity of membrane were also improved with the addition of A-HNTs. More importantly, A-HNTs@PVDF membrane exhibited excellent rejection stability and reuse performances after several times fouling and washing tests. It can be expected that the present work will provide insight into a new method for membrane modification in the field of wastewater treatment.

Novel hydrophilic PVDF ultrafiltration membranes based on a ZrO 2 –multiwalled carbon nanotube hybrid for oil/water separation

A novel hydrophilic PVDF composite membrane based on ZrO2–multiwalled carbon nanotubes (MWCNTs) hybrid was prepared by a simple phase-inversion method. ZrO2 nanoparticles were firstly loaded on the surface of MWCNTs via hydrothermal route, which was characterized by Fourier-transform infrared, X-ray diffraction, thermogravimetric analyzer, scanning electron microscopy (SEM), and transmission electron microscopy. It was found that the ZrO2–MWCNTs hybrid formed network structures within the PVDF matrix, avoiding the aggregation of nanofillers. Then, the effects of ZrO2–MWCNTs hybrid on the performances of ultimate PVDF membrane were systematically investigated. The microstructure and surface morphology of novel membranes were observed by SEM and atomic force microscopy. The results indicated that ZrO2 were dispersed homogeneously on the surface of MWCNTs. The as-prepared membrane exhibited enhanced pure water flux and a lower contact angle than those of pure PVDF membrane. Furthermore, the as-prepared membranes processed also improved separation efficiency against oil/water emulsions and achieved better rejection ratio and good durable antifouling performance. In general, ZrO2–MWCNTs/PVDF membrane may provide a potential application against complex oil/water systems.

Two step hydrothermal synthesis of flowerbud-like magnetite/graphene oxide hybrid with high-performance microwave absorption

A novel flowerbud-like magnetite/graphene oxide (GO) hybrid was synthesized from facile two-step hydrothermal process by using FeCl3 as iron source, ethylene glycol as the reducing agent, and graphene oxide as template. The magnetite nanoparticles with the diameters of 70–80 nm were attached onto the surface of graphene oxide through the two-step self-assembly process which enhanced the magnetic properties of the hybrids. The final flowerbud-like magnetite/graphene oxide hybrid emerged with the saturated magnetization of ~84.5 emu g–1. More importantly, owing to the combined contribution of enhanced dielectric and magnetic properties, the maximum microwave absorption of as-prepared magnetite/GO hybrid reached 30 dB with a thickness of 4 mm. Besides, the absorption bandwidth with a reflection loss above 23 dB ranged from 6.0 to 11.5 GHz.

Novel amino-functionalized Fe3O4/carboxylic multi-walled carbon nanotubes: One-pot synthesis, characterization and removal for Cu(II)

A novel amino functionalized Fe3O4/multi-walled carbon nanotubes hybrid was synthesized by a facile and efficient one-pot solvothermal process. The 3-aminophenoxyphthalonitrile which was regarded as phthalonitrile monomer was introduced into the solvothermal process and promoted the phthalocyanine cyclization reaction, finally forming the amino functionalized hybrid. The structure, composition, and morphology were characterized by FTIR, XRD, XPS, SEM, and TEM. It was found that the monodispersed amino functionalized Fe3O4 spheres with diameters of 180–220 nm were uniformly attached on the surface of multi-walled carbon nanotubes. Owing to the synergistic effect between the amino groups and magnetic carbon nanotubes, the asprepared hybrid exhibited the high separation efficiency when used to remove Cu(II) from aqueous solutions. The adsorption isotherms of the as-prepared hybrid for Cu(II) removal fitted the Langmuir model, the maximum adsorption capacity of our amino-functionalized Fe3O4/MWCNTs hybrid calculated from the isotherm model is 30.49 mg g–1. This work demonstrated that the amino functionalized Fe3O4/multi-walled carbon nanotubes hybrid was promising as efficient adsorbent for heavy metal ions removal from wastewater in low concentration.

Hydrothermal synthesis of graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite for removal of Cu (II) and methylene blue

In this work, highly activated graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite adsorbent was prepared from a simple hydrothermal route by using ferrous sulfate as precursor. For this purpose, the graphene oxide/multiwalled carbon nanotube architectures were formed through the π-π attractions between them, followed by attaching Fe3O4 nanoparticles onto their surface. The structure and composition of as-prepared ternary nanocomposite were characterized by XRD, FTIR, XPS, SEM, TEM, Raman, TGA, and BET. It was found that the resultant porous graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite with large surface area could effectively prevent the π-π stacking interactions between graphene oxide nanosheets and greatly improve sorption sites on the surfaces. Thus, owing to the unique ternary nanocomposite architecture and synergistic effect among various components, as-prepared ternary nanocomposite exhibited high separation efficiency when they were used to remove the Cu (II) and methylene blue from aqueous solutions. Furthermore, the adsorption isotherms of ternary nanocomposite structures for Cu (II) and methylene blue removal fitted the Langmuir isotherm model. This work demonstrated that the graphene oxide/multiwalled carbon nanotube/Fe3O4 ternary nanocomposite was promising as an efficient adsorbent for heavy metal ions and organic dye removal from wastewater in low concentration.

Exfoliated graphite nanoplatelets/poly(arylene ether nitrile) nanocomposites In situ synthesis, characterization, and enhanced properties

In this work, we demonstrate a method for synthesis of exfoliated graphite nanoplatelets (xGnPs)/poly(arylene ether nitrile) (PEN) nanocomposites via an efficient in situ polymerization. The GnPs were treated by the ultrasonic bath to reduce the layers of the GnPs, where the PEN were intercalated subsequently. Therefore, the dispersion of xGnP in the PEN resin was enhanced through in situ polymerization, which was characterized and confirmed by scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. It was found that the tensile strength and modulus were greatly enhanced with the addition of xGnP. For 2.5 wt% of xGnP-reinforced PEN, the tensile strength and modulus were increased to 115 MPa and 3121 MPa, respectively. Owing to the well dispersion of xGnP, the low rheological percolation of 2.5 wt% for PEN nanocomposites was obtained. Besides, with 1 wt% of xGnP, the corresponding initial decomposition temperature (Tin) increased from 451°C in pure PEN to 470°C. The addition of xGnP showed enhanced thermal stability of PEN nanocomposites, which demonstrated a promising method for preparing advanced polymer-based nanocomposites.

The inhibition performance of hydroxy lauric imidazoline for mild steel in chloride solution saturated with CO2

In the paper, a novel hydroxy lauric imidazoline (HL-IM) was synthesized using lauric acid and ethylene diamine as raw materials. Methanol reaction method was introduced to prepare the hydroxy lauric imidazoline (HL-IM). According to the results of experiments, the optimum synthesis conditions of methanol reaction was determined through orthogonal experiment, which were: methyl laurate: ethylene diamine = 1: 1, sodium methoxide (0.75 wt %), reaction temperature 100°C, reaction time 2 h. The inhibition efficiency of HL-IM inhibitor was investigated in the condition of 5 wt % NaCl solutions saturated with CO2 at 333.15 K for 72 h. With 150 mg L–1 inhibitor dosage, the efficiency of inhibition reached 90.17% by weight loss method. Through film-forming property, foaming characteristic, and emulsification tendency test, it w a s shown that HL-IM had good water-solubility, a smaller emulsification tendency in 5 wt % NaCl solution, and a little foaming performance. Meanwhile, referring to the polarization curves tests, the synergistic effect of HL-IM with the potassium iodide, methylbutynol, and cetyltrimethyl ammonium bromide was studied.