Qibing Chang

Preparation and application of positively charged quaternized chitosan/PEI composite nanofiltration membranes

AbstractMembrane processes are gaining importance in water applications as a result of the advances in membrane technology and the increasing requirements on water quality. In this work, 2-hydroxypropyltrimethyl ammonium chloride chitosan with positively charged character and good membrane-forming ability was utilized to fabricate the functional layer of the composite nanofiltration (NF) membrane. Reinforced polyetherimide ultrafiltration membrane was used as the support layer for its excellent thermal and solvent resistance. Effects of polymer concentration, reaction time, cross-linking agent concentration, and cross-linking temperature on membrane performance were studied in detail. When the composite membrane was prepared under optimized conditions and tested at 0.3 MPa and 20°C, the flux of the composite NF membrane was about 10.9 L/m2h and the MgCl2 rejection of it was about 83.1%. The surface morphologies of the composite membrane and substrate membrane were observed by scanning electron microscopy....

Evidence of ZrO2 sol–gel transition by gelation time and viscosity

Sol–gel transition is a stage of the sol that evolves towards the formation of a gel-like network and that exhibits gradually a mobility loss. Hence, the measurement of both viscosity and gelation time is expected to evidence the sol–gel transition occurrence. ZrO2 sols were prepared using zirconium oxychloride octahydrated as precursor material. The structures of the sols before and after gelation were characterized by TEM. Gelation time depends on the concentrations of the reactants and the aging temperature. Viscosity increases linearly with the gelation time firstly, and then increases exponentially nearby the sol–gel transition point. TEM results show the gel is granular before the sol–gel transition point, and appears as brain-like structure after this point. The determination of the sol–gel transition point is to enable the optimum aging time of a sol and to perform the next operations which determine the desired shape of gel (bulk, film, powder, etc.).

Preparation and Characterization of Coated Carbon Black Pigment

Black pigment is an important pigment in the ceramic decoration. The traditional black pigment is spinel type matter containing Co, Fe or Cr elements. Carbon black is the best black pigment and is nontoxic. However, carbon black is oxygenated in the ceramic sintering process at atmosphere. Carbon black enclosed in the crystal latter of ZrSiO4 was reported. However, the content of carbon black is little which decreases the color generation. Carbon black coated with SiO2 was prepared by sol-gel method using combustion method using SiO2 sol and black ink as raw materials. The obtained black pigmenSubscript textt was characterized by XRD, TEM and ultraviolet-visible spectrophotometer. The results show that the black pigment does not change its color after calcinations at 1300 °C at atmosphere implying the carbon black is coated completely with SiO2.

Effect of hydrophilic modification with nano-titania and operation modes on the oil–water separation performance of microfiltration membrane

AbstractThe tubular Al2O3 microfiltration membranes modified with nano-TiO2 coating were applied in the separation of waste oil-in-water emulsion. The separation performances of the MF membranes with and without nano-TiO2 modification were studied under two different operation modes, i.e. the circulation mode and the concentration mode, respectively. The circulation mode in which the oil concentration in feed keeps constant simulates the condition of the great amount of feed to be treated, while the concentration mode in which the oil concentration in feed increases with the extraction of the filtrate simulates the condition of a small amount of feed to be treated. The results show that the operation mode has a less effect on the flux of the MF membranes, but has an important effect on the oil concentration of filtrate for the unmodified membrane. The oil concentration in filtrate under concentration mode is higher than that of circulation mode. For the modified membrane, the operation mode has a less eff...

Microstructure evolution and properties of YSZ hollow fiber microfiltration membranes prepared at different suspension solid content for water treatment

AbstractYttria-stabilized zirconia (YSZ) hollow fiber ceramic membranes for microfiltration applications were prepared by the phase inversion and sintering technique. The influence of suspension solid content on the rheological behavior of suspension, and the microstructure and properties of the hollow fiber membranes were investigated. With the addition of YSZ powder, the viscosity of the spinning suspension increased obviously, and the rheological behavior of the suspension changed from Newtonian fluid into thinning behavior fluid. The increment of suspension viscosity upon the YSZ content led to a more porous inner surface, larger inner finger-like pores extending outward, and reduced outer finger-like layer for the prepared hollow fiber membrane. When the YSZ content was increased to 65%, a double-layer structure mostly consisting of outer sponge-like layer and inner finger-like structure layer was formed. The pure water flux of the hollow fiber membrane decreased with the increment of YSZ content, wh...

Particle Size and Chroma Control of CoAl2O4 Pigment

To meet the requirement of ceramic pigment for ink jet printing, CoAl2O4 pigment was prepared by nitrate-glycine method. The effect of nitrate/glycine ratio, calcination temperature and organic sacrificial agent on the particle size and chroma of the blue pigment were considered. The results show that the particle size of the pigment increases with the increase of glycine in the ratio and the decrease of the calcination temperature. However, the increase of the calcination temperature results in the broadening of the particle size distribution of the pigment. The addition of the organic sacrificial agent contributes to decrease the particle size of the pigment, which is about 2.0 μm. The chroma of the pigment is L*=47.62、a*=9.49、b*=-51.41. The blue pigment can be used in ink jet printing.

Investigation of Cobalt-Free Cathode Material Ba0.5Sr0.5Fe0.8Cu0.2O3−δ for Micro-Tubular SOFC with Asymmetric Structure Anode

A cobalt-free perovskite oxide Ba0.5Sr0.5Fe0.8Cu0.2O3−δ (BSFCu) is applied as the cathode material for intermediate temperature micro-tubular solid oxide fuel cells (SOFCs) with asymmetric structure anode. The NiO-YSZ hollow fiber anode as support was prepared by the phase inversion technique. The as-prepared fiber anode shows a special asymmetric structure consisting of porous sponge-like structure in the middle and finger-like porous structure on the inner and outer side. Dense thin YSZ electrolyte membrane and SDC transition layer were deposited on the NiO-YSZ hollow fiber anode by a vacuum-assisted dip-coating and co-sintering technique. Laboratory-sized micro-tubular single cells of NiO-YSZ/YSZ+SDC/BSFCu-SDC were tested at 650-750°C with humidified H2 as the fuel and static ambient air as the oxidant. The peak power densities of 437.2, 326.5 and 214.4 mWcm-2 can be obtained at 750, 700 and 650°C, respectively. The experimental results indicate that the cobalt-free perovskite oxide BSFCu is a promising cathode material candidate for the developed intermediate temperature micro-tubular SOFC with asymmetric hollow fiber anode.

Nano-Sized Metal Oxide Modification Applied in Microfiltration Membrane Technology

Membrane surface modification is the important method to decrease membrane fouling. Recent efforts have been made to develop the hydrophilic modified ceramic membrane with nano-sized inorganic coating in our research group. In the modified membrane, the nano coating does not form a separating layer, just distributes uniformly on the surface of the membrane pore wall. It results in that: (1) if the feed is water, the water flux of the modified membrane is higher than that of the unmodified one despite the fact that the mean membrane pore size decreases after the modification; (2) if the feed is oily emulsion, the steady flux is obtained in a short time and keeps in the following time. The flux is far higher than that of the unmodified one because the hydrophilic nano coating prevents the cake from forming on the membrane surface. The nano-sized metal oxide modification application in the membrane technology not only expands the newly research area of the membrane technology but also makes the modified ceramic membrane have a good perspective application in the industry. This paper will introduce the development of the modified membrane with nano inorganic coating and give a clear future research direction.

A New Method to Analysis the Co-Sintering of NiO/YSZ-YSZ Coating

To explain the deformation during the co-sintering of NiO/YSZ-YSZ coating, the sintering shrinkage of NiO, NiO/YSZ and YSZ were measured by dilatometer. The coefficient of deformation variable (CDV, α) is defined to describe the difference of the sintering behaviors between the layers constrained.

Preparation of Zircon-Encapsulated Carbon Black Ceramic Pigment Using the Collapsed Mesoporous-Structure

The black zircon encapsulated carbon black (C@ZrSiO4) ceramic pigment is prepared using the collapsed mesoporous-structure to improve the coverage of carbon black. In the preparation process, the tri-block copolymer (Pluronic P123, EO20PO70EO20) is used as both the template of mesoporous zirconia and the source of carbon black under the calcination at 300 °C in Ar. Carbon black originated from P123 distributes uniformly in the mesoporous zirconia. After mixed with SiO2 sol and re-calcinated at over 800 °C, the procedure loses gradually the mesoporous structure and reacts with SiO2 to generate zircon. Carbon black is encapsulated completely by dense zircon. After calcined at 900 °C in air to remove the possible uncoated carbon black, the obtained pigment still has the deep black hue (L* = 24.14). This preparation method provides a simple way to prepare black ceramic pigment.