Showing papers by "Huijun Ren published in 2022"

Robust, Superhydrophobic and Self‐healing films with Hierarchical Nacre Mimetics: A High‐Efficiency and “Green” Route based on Solvent‐free polyurethane/Modified Graphene Oxide Composites

Abstract: Superhydrophobic and self-cleaning materials have attracted tremendous attention because of their broad applications. However, it is still challenging to develop excellent films exhibiting both reparable superhydrophobic and robust mechanical properties by an environmentally friendly method. Inspired by a natural nacre structure, the novel multi-layered inorganic-organic films consisting of n-octadecylamine-modified graphene oxide (NGO) and solvent-free self-healing polyurethane synthesized by Diels-Alder reaction (SFPU-DA) are demonstrated. Through the layer-by-layer assembly technology, super-hydrophobic and self-repairing solvent-free polyurethane composite films (NGO/SFPU-DA films) are prepared. The NGO/SFPU-DA composite films exhibit healing of surface creases and cracks within 120 s at 120 °C. Meanwhile, the contact angle and sliding angle of the films can be as high as 151° and 8°, respectively. Noticeably, even after 21 times of rubbing, the superhydrophobicity of the obtained films does not significantly reduce. In addition, the tensile strength and peel strength of NGO/SFPU-DA films can reach 22.6 MPa and 88.6 N/30 mm. Moreover, the steel coated with NGO/SFPU-DA films exhibits lower corrosion current density and better corrosion resistance than the single NGO/SFPU-DA film and uncoated steel. The method may provide an effective way to obtain excellent self-cleaning materials with long service life.

Effects of potassium ferrate-walnut shell pretreatment on dehydration performance of residual sludge

Abstract: Sludge dehydration is not only the first process of sludge reduction but also difficult for sludge treatment and disposal, while the high moisture content of sludge would also limit its resource utilization. In this paper, the residual sludge was treated by the strong oxidizing property of potassium ferrate (PF), and walnut shells were used as a skeleton builder to obtain the recycling dehydrated sludge. It also provides a new solution for the poor stability of PF in the treatment of sludge and waste walnut shells. The experiment results showed that the optimum dosage of PF and walnut shell was 60 mg/gDS and 0.8 g/gDS, respectively, and the water content of the combined PF and walnut shell treatment decreased by 5.2% and 3.7% compared to that of PF conditioning alone and walnut shell conditioning alone, respectively. In addition, scanning electron microscopy and three-dimensional fluorescence spectroscopy revealed a large number of cracks on the sludge surface after the combined treatment, and the sludge floc structure became more loose and dispersed, and the hydrophobic substances humic acid and fulvic acid increased, indicating that the dewatering performance of the sludge was effectively improved, further confirming that the combined PF and walnut shells treatment provides a new idea and method for sludge dewatering.

Anisotropic saturation magnetization in flexible BiFe0.95Cr0.05O3/BiFe0.95Mn0.05O3 superlattice thin films by sol-gel

Abstract: The flexible BiFe 0.95 Cr 0.05 O 3 /BiFe 0.95 Mn 0.05 O 3 (BFCO/BFMO) superlattice thin films with excellent anisotropic saturation magnetization phenomena were successful prepared by sol-gel on fluorophlogopite (F-Mica) substrates. The values of the saturation magnetization (in-plane and out-of-plane; unbent condition) decreased gradually with the increase of thickness of the flexible BFCO/BFMO samples, which is because the increase in thickness leads to the change of the stress (between the film and the substrate) (inside the superlattice film). Meanwhile, the difference between the in-plane and out-of-plane saturation magnetization of the samples increased gradually with the increase of the thickness. The anisotropic saturation magnetization of the flexible samples can be attributed to the maximum preferred orientation and large grain size induced by the single crystal substrate and superlattice structure. It is expected that the flexible BFCO/BFMO thin films with excellent anisotropic saturation magnetization can be further developed for flexible devices. • The flexible BFCO/BFMO thin films with the anisotropic saturation magnetization were successfully prepared. • The anisotropic saturation magnetization can be attributed to the preferred orientation and large grain size. • The flexible BFCO/BFMO thin films with anisotropic saturation magnetization can be developed for flexible devices.