Suping Cui

Self-cleaning and antifouling nanofiltration membranes—superhydrophilic multilayered polyelectrolyte/CSH composite films towards rejection of dyes

Superhydrophilic poly(ethyleneimine)/poly(sodium-4-styrenesulfonate) (PEI/PSS)–calcium silicate hydrate (CSH) multilayered membranes (PEI/PSS)2.0(PEI/PSS–CSH)n on polyacrylonitrile (PAN) substrate were prepared via layer-by-layer (LbL) assembly with in situ precipitation of consecutive Ca2+-integrated multilayered polyelectrolytes and sodium silicate. The surface structure and properties of these multilayered membranes (PEI/PSS)2.0(PEI/PSS–CSH)n were characterized by zeta potential, infrared resonance spectra, water contact angles, scanning electron microscopy, and atomic force microscopy, and the separation performances were evaluated by rejection of dyes, such as xylenol orange (XO) and rhodamine B (RB). The long term performance, self-cleaning and antifouling behaviors were investigated by retention of aqueous solutions of both dyes and bovine serum albumin (BSA) aqueous solution. The results indicated that the in situ incorporation of controlled CSH contents into PEI/PSS multilayers greatly improved the hydrophilicity of the multilayered membranes, resulting in the formation of a superhydrophilic (PEI/PSS–CSH)2.0 membrane with a water contact angle of 2.1° and the highest permeate fluxes of 191.5 and 183.5 L m−2 h−1 MPa−1 accompanied by the rejection of 94.0% and 91.2% for XO and RB aqueous solutions, respectively. When the number of assembled (PEI/PSS–CSH)n multilayers was higher than 2.0 bilayers, the rejection increased but the flux markedly decreased to XO and RB dyes, showing a characteristic trade-off phenomenon. Moreover, the superhydrophilic (PEI/PSS–CSH)2.0 membrane possessed a higher antifouling and self-cleaning behavior than the hydrophilic polyelectrolytes (PEI/PSS)2.0.

One-Step Transformation from Hierarchical-Structured Superhydrophilic NF Membrane into Superhydrophobic OSN Membrane with Improved Antifouling Effect

The hierarchical-structured superhydrophilic poly(ethylenimine)/poly(acrylic acid) (PEI/PAA)calcium silicate hydrate (CSH) multilayered membranes (PEI/PAA-CSH)n were prepared as aqueous nanofiltration (NF) membrane, and then they were transformed into superhydrophobic organic solvent nanofiltration (OSN) membranes by one-step modification of trimethylperfluorinatedsilane (PFTS). Investigation on surface structures and properties of these multilayered membranes (PEI/PAA-CSH)n indicated that the hierarchical-structured (PEI/PAA-CSH)n multilayered membrane produced by in situ incorporation of CSH aggregates into PEI/PAA multilayers facilitated its one-step transformation from superhydrophilicity into superhydrophobicity. Both of the superwetting membranes showed better nanofiltration performances for retention of dyes of water and ethanol solution, respectively. Moreover, the long-term performance and antifouling behaviors, investigated by retention of methyl blue (MB), bovine serum albumin (BSA), and humic acid (HA) aqueous water solution and nonaqueous ethanol solution indicated that both of the superhydrophilic and superhydrophobic membrane showed higher stability and excellent antifouling property.

Characteristics of Self-Healing Microcapsules for Cementitious Composites

Urea formaldehyde/epoxy resin microcapsules were prepared by an in situ polymerization method and the effect of emulsifier on the syntheses process of the microcapsules was discussed. The surface morphology of the microcapsules was observed by optical microscopy and scanning electron microscopy (SEM). Chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermal stability was obtained using simultaneous thermal analysis (STA). The microcapsules were composed of urea-formaldehyde resin shell and epoxy resin core. Emulsifier played an important role in the polymerization process when the core material was packed by pre-polymer, so the effects of different emulsifiers (OP-10, SDS and SDBS) were discussed respectively. Results showed that the particle size of the microcapsules was uniform when SDBS as an emulsifier. Microcapsules showed good thermal stability below 240 °C and the initial decomposition temperature of the microcapsules was 265 °C. The core materials released after microcapsules rupturing, which could be proven by the images of SEM. When implanted in cementitious composites, complete shape of microcapsules and good interface between microcapsules and cement specimen substrate could also be observed.

Influence of Synthesis Temperature on MnOx/TiO 2 SCR DENOx Catalyst Prepared with Acidolysis Residue

This paper focused on MnOx/TiO2 SCR DENOx catalytic materials prepared with acidolysis residue (a solid waste which was generated during the sulfate process of the titanium oxide industry), and investigated the influence of synthesis temperature on catalytic properties and microstructure of the catalytic materials. Two different synthesis temperatures including ambient temperature and 80 ℃ were employed to prepare the catalytic materials. The modifications of textural, surface properties and catalytic activity of catalyst prepared at different temperatures were compared. Results showed that the catalyst prepared by precipitation method at room temperature (ammonia-hydrogen peroxide was used as precipitant and the calcination temperature is 250 ℃), leads to a higher NOx conversion rate. The NOx conversion at 100 ℃ is 80%, even 95% at 130 ℃. Results from XRD analysis indicate that the catalyst synthesized at room temperature results in a less sharp peak of Mn3O4. The active substances of manganese oxides are highly dispersed on the surface of the catalytic materials in amorphous state. Furthermore, H2-TPR demonstrates that the catalyst synthesized at room temperature has a higher redox activity and the MnO2 phase occupies the leading position of MnOx, which contributes to the excellent NOx conversion rate of the catalytic.

The Influence of Volume Changes in Portland and Calcium Sulfoaluminate Binary Cement

The long-term volume changes of Portland-Calcium sulfoaluminate cement systems has been studied for samples cured under different conditions. Three curing conditions were chosen in this study and the composite cement systems showed different results with different CSA dosages. Progressively higher amount of CSA was added to the composite cement system and it was found that there was a critical dosage of CSA leading to unstable expansion and failure of the samples by curing under water. But in drying condition, the systems showed shrinkage and the degree of volume changes were similar than expansion by curing under water. By selecting the composition of CSA-PC systems and curing conditions, the volume stability of composite cement could be controlled.

Mechanism of SO 2 Influence on Mn/TiO 2 for Low Temperature SCR Reaction

Mn-based catalysts extremely restricted with the deactivation by SO2. In this paper, catalysts of Mn/TiO2 prepared by co-precipitation method for low temperature selective catalytic reduction (SCR) of NO with NH3 under the influence of SO2. For Mn/TiO2, NO conversion decreased rapidly from 90% to about 55% at 200 ℃ in the presence of SO2. We reveal the mechanism of SO2 effect on the adsorption of NH3 and NO based on DRIFT and TPD. The result show that SO2 can reduce the adsorption amount of NH3 on the Lewis acid sites and react with NH4+ to form NH4HSO3 on the Bronsted acid sites. In the meantime, SO2 can inhibit the adsorption of NO took part in the SCR reaction on the surface of catalyst due to the mechanical of competitive adsorption. These poisoning phenomenon of SO2 hinder the proceeding of SCR reaction.

Preparation of Micro-porous Chitosan Membrane and Its Adsorption Property for Cr(VI) Ions

Chitosan (CS) micro-porous membranes were prepared by blending-phase inversion method using chitosan as film-forming polymer, polyethylene glycol (PEG) as porogen and glycerol as plasticizer. Adsorption experiments were conducted under varied Cr(VI) ions concentration, pH values, contact time and temperature. The results indicated that when the ratio of chitosan to polyethylene glycol and glycerol was 1:0.5:0.5 at pH of 2.79, the prepared CS membrane exhibited the highest adsorption capacity of 168.41 mg g−1 under Cr(VI) ions concentration of 100 mg L−1, contact time of 4 h, and membrane dosage of 10.0 mg. Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms at different Cr(VI) ions concentrations. The equilibrium data was found to be fitted well to the Langmuir isotherm. Pseudo-first-order and pseudo-second-order kinetics models were used to describe the membrane adsorption.

Effect of Conductivity and Radiation on Heat Dissipation Performance of Coating

Aiming at the problem of heat dissipation of electronic devices in low temperature environment, the effect of thermal conductivity and emissivity of coating on its heat dissipation performance was studied by theoretical calculations and experiments in this study. The results show that the heat dissipation performance of organic coating with emissivity of 0.7–0.95 is improved as its thermal conductivity increasing. And temperature difference between inside and surface of object is inversely proportional to thermal conductivity. That is, when thermal conductivity exceeds a certain value, it will no longer affect heat dissipation performance of coating. In addition, emissivity of coating directly affects its cooling performance, and the proper matching interaction between thermal conductivity and emissivity of coating can enhance heat dissipation effects. In the case of non-forced convection cooling, the thermal conductivity of the organic coating is preferably 2–10 W/m·K.