The poor mechanical strength of superhydrophobic surface limits its use in civil aviation. In this work, superhydrophobic surfaces with open and closed microstructure design were prepared, and their hydrophobicity and icephobicity over icing/de-icing cycles were thoroughly studied. For all samples, contact angle decreased and contact angle hysteresis increased over time. However, surface with interconnected hollow honeycomb microstructure design kept its Cassie-Baxter state even after 20 times icing/de-icing cycles, while surface with repeated individual post microscopic unit lost its superhydrophobicity only after six times icing/de-icing cycles. The interconnected hollow honeycomb microstructure design strengthened surface mechanical strength by lowering the damage to microscopic unit. The freezing time for water droplet on surface with interconnected hollow honeycomb microstructure design was only slightly shortened over time. The difference in water/ice-solid contact area for surfaces with different nano-microscale design also led to the difference in wetting and ice-retarding ability. Surface with interconnected hollow honeycomb microstructure design showed the strongest ice-retarding ability followed by surface with interconnected hollow brick, ladder type, and triangle shape microstructure design.

Earlier work showed that the commercial granular activated carbon (GAC) could effectively remove large non-polar molecules, but showed poor removal efficiency for small polar compounds such as isopropyl alcohol (IPA) [Schmotzer et al. Clean Technol. Environ. Policy 2002;4:125; Cong et al. J. Phys. Chem. C 2007;111:6976]. To achieve the goal of increasing the lifetime and removal efficiency of GAC bed for small polar organic compounds in ultrapure water (UPW), the synergistic partial photocatalytic oxidation and adsorption system using commercial GAC coated with nitrogen doped titanium dioxide as an adsorbate was proposed in this work. The influence of operating factors such as UV intensity, flow rate, feed concentration, and the sudden injection of air or inorganic acid on IPA removal efficiency was systematically investigated. Compared to the traditional GAC adsorption bed, at feed total organic carbon (TOC) concentration of 800 ppb, the lifetime of GAC bed in this synergistic photocatalytic oxidation and adsorption system was extended from 348 to 600 min and the outlet TOC concentration was decreased from 793 to 499 ppb. The difference of the TOC outlet concentration in those two configurations was attributed to the photocatalytic effect by GAC coated with nitrogen doped titanium dioxide. The reactions between oxidation radicals and organic contaminants caused the majority of IPA to be decomposed into secondary organic compounds such as acetone and acetone had already been shown a higher affinity to GAC than that of IPA. Experiments also demonstrated the injection of air or inorganic acid in the stream would facilitate the removal of IPA in UPW.

The incomplete regeneration of diesel particulate filter may cause a local build-up of the soot on the partially regenerated areas during next filtration cycle. This may be one of reasons causing the melting of the ceramic filter during regeneration. In this paper, we investigated several situations at which the particulate matter was partially regenerated. The simulations illustrated that at stationary feed conditions, the influence of nonuniformity of soot loading on the peak temperature rise was less important. When regeneration was conducted at transient feed conditions, the peak temperature attained under the condition of uneven soot distribution along the channel, especially more soot accumulated near the end of the diesel particulate filter, was much higher than that attained under the condition of even soot distribution inside the channel.

To achieve the goal of implementation of low-energy and low-chemical usage for trace organic compound removal, the hybrid oxidation/adsorption purification system using nitrogen-doped titanium dioxide catalytic oxidation followed by activated carbon adsorption was proposed in this paper. When isopropyl alcohol, ethylene glycol, and urea were selected as model components, superior oxidation effects were achieved by combination of nitrogen-doped titanium dioxide with 254 nm UV unit than by traditional high-energy-consumed 185 nm UV unit, which indicated such configuration would be an ideal candidate to replace the current high-energy-consumed UV unit. By incorporating this new configuration into the semiconductor wastewater recycling system, the granule-activated carbon bed adsorption efficiency for total organic carbon was compared with the granule-activated carbon adsorption efficiency for total organic carbon in traditional purification system, where the 185 nm UV lamp was used as oxidation unit. The experimental results showed that the hybrid low energy consumption catalytic oxidation/adsorption system had higher efficiency than the traditional high-energy-consumed oxidation/adsorption system for trace organic compound removal. This was because the radicals formed in the UV oxidation process reacted with the organic compounds adsorbed on the activated carbon and regenerated the adsorption sites. This selfcleaning mechanism effectively extended the lifetime of activated carbon bed and increased its adsorption capability.

The high vapor pressure of diethylene glycol monomethyl ether, the only approved civil aviation fuel system icing inhibitor (FSII), causes the peeling of fuel tank topcoat material. This leads to increased maintenance costs and decreased aircraft mission capabilities. Triethylene glycol monomethyl ether (TriEGME) has been proposed as a potential replacement as it has a low vapor pressure and can partition into any free water in the fuel forming a solution with a low freezing point. However, its use has not been approved by airworthiness authority because very few data are available for its impacts on water solubility and icing behavior in fuel. The effects of TriEGME on water solubility, solidification temperature, and water icing behavior in fuel were thoroughly studied. At added concentration ranging from 0.10 to 0.15 vol. % water solubility in jet fuel almost tripled compared with that without FSII. The solidification temperatures for water in fuel with FSII and for mixture of water and FSII decreased with increased FSII concentration. Moreover, partition coefficient, defined as equilibrium FSII concentration in aqueous phase divided by equilibrium FSII concentration in fuel phase, decreased with increased FSII concentration in fuel. At equilibrium condition with fixed FSII concentration in fuel, decrease in fuel temperature led to an increase in partition coefficient. An estimation of required dosage for TriEGME to prevent water icing in fuel can be achieved by comparison of TriEGME concentration in aqueous phase with its corresponding freezing temperature.