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The utilization of mechanical energy to control water pollutants under dark conditions is currently a point of study focus. Herein, biochar -zinc oxide (BC-ZnO) composites with various structures were synthesized by co-pyrolysis of cotton and ZnO at different temperature and used for tribo-catalytic reaction. The introduction of BC can improve charge transmission and separation efficiency. Ultraviolet photoelectron spectra (UPS) and density functional theory (DFT) calculation prove the addition of BC can reduce work function of ZnO, and enhance its electron-donating ability. Specially, suitable adsorption amount is the key factor to improve the tribo-catalytic performance. When the pyrolysis temperature is 600 °C, BC-ZnO has the best degradation efficiency, which can degrade 90% Rhodamine B (RhB) in 75 min, while ZnO can degrade only 38%. On this basis, using bovine serum albumin (BSA) as a model, the effect of tribo-catalytic reaction on controlling proteins in water was studied by fluorescence excitation-emission matrix spectroscopy (3D EEM) and infrared microscope, and the transformation of proteins was further analyzed. This study provides a new strategy to improve the tribo-catalytic performance of ZnO, and explores its application prospects of biological wastewater control.

The control of interfacial microbial pollution is of great significance for water safety. Herein, the tribo-catalysis ability of zinc oxide (ZnO) has been investigated, which can realize the control of tightly-bound extracellular polymeric substances (T-EPS) in water under dark environment. The DFT calculation proves the Fe doping introduces the impurity level and decreases the work function from 5.071 eV to 5.045 eV, improves the charge separation of ZnO, and eventually enhances the catalytic reaction efficiency. Characterizing the catalytic reaction process by three-dimensional fluorescence (3D EEM) and fluorescence regional integration (FRI) method, it is found that the T-EPS solution can be degraded 75.8% by Fe-ZnO in 12 min, while ZnO can only degrade 32.2%. Combining with high-resolution scanning probe microscope (HR-SPM) and attenuated total reflection method (ATR-FTIR), hydration layers consist with hydroxyl layer (∼0.23 nm) and water molecular layer (∼0.27 nm) are observed at the interface between Fe-ZnO and T-EPS solution, and terminal hydroxyl group (OHt) is considered to be the active site for the generation of radicals. This study provides an idea for exploring the mechanism of tribo-catalytic reaction and shows its application prospect in the field of microbial inhibition in water.

Traditional insulating-oil-regeneration methods have been found inefficient and unable to clear fine particles and acid degradation products. This work aims to improve the oil-regeneration performance of Poly(vinylidene fluoride) (PVDF) nanofibers by variable electrospinning voltages and PVDF solution concentrations. The PVDF/dimethylformamide (DMF) solutions of varying concentrations were utilized for electrospinning at different electric voltages. Results from Fourier-Transform Infrared (FTIR) spectrum and Scanning Electron Microscopy (SEM) show that with the increase of PVDF concentration, the crystalline $\alpha$ phase in the nanofibers was seen gradually decreased, while the $\beta$ phase got increased. The increased voltage from 16 to 20 kV led to decreased nanofiber diameter and narrowed diameter distribution. However, a high voltage above 20 kV has led to the opposite tendency. After filtration by the nanofibers prepared at 20 kV and 14% concentration, the AC breakdown voltage of the aged oil shown 52.5% enhanced, and the relative permittivity $\varepsilon_{r}$ as well the loss factor tan $\delta$ of the aged oil decreased distinctly to the level which is comparable to new insulating oil. The electrospun PVDF nanofibers have shown good performance on the regeneration of aged insulating oils. The electric voltage and the solution concentration during electrospinning are critical to optimizing the regeneration performance of the nanofibers.

The application of Zinc oxide has drawn great attention in bacterial inhibition and contaminant degradation field in recent years. The internal structure and the morphology of the material was characterized by XRD, XPS, SEM, TEM. The dopant of 1 wt% graphene oxide（GO） and 30 wt% Al2O3 shows excellent piezocatalytic and antibacterial ability. Application potential of the material is investigated by the degradation of RhB and the inhibition of Bacillus. It is found that the RhB solution can be degraded 92.5% by ZA-GO in 15 min, while ZnO can degrade 64.2%. It shows superior catalytic behavior in successive experiments of degradation of RhB without obvious decrease in efficiency. The quenching experiment combined with ESR spectrum demonstrate that both •O2- and •OH radicals were generated, while •OH did the most damage. Bacterial inhibition tests have also proven that the generation of reactive oxygen species cause the bacteria inactivated. In this work, a novel composite ZnO-Al2O3/GO has been successfully prepared based on mechanical synthesis method. Graphene oxide has higher mechanical strength and higher specific surface area. Zn ions doping carbon materials not only increases its stability, but also promotes its conductivity. The doping of Al atoms effectively reduce the work function of ZnO. Graphene oxide together with alumina coordinate the band gap of piezoelectric materials ZnO and the catalytic reaction efficiency was dramatically enhanced. What’s more, this work provides a facile approach eliminated the use of solvents and organic reagents, ensuring greater environmental safety. The novel zinc oxide matrix composites are depicted as a promising candidate to be used as intelligent antibacterial agent and alleviate environmental pollution.