Complex pollutants are discharging and accumulating in rivers and oceans, requiring a coupled strategy to resolve pollutants efficiently. A novel method is proposed to treat multiple pollutants with C,N co-doped TiO2 hollow nanofibers coated stainless steel meshes which can realize efficient oil/water separation and visible light-drove dyes photodegradation. The poly(divinylbenzene-co-vinylbenzene chloride), P(DVB-co-VBC), nanofibers are generated by precipitate cationic polymerization on the mesh framework, following with quaternization by triethylamine for N doping. Then, TiO2 is coated on the polymeric nanofibers via in-situ sol-gel process of tetrabutyl titanate. The functional mesh coated with C,N co-doped TiO2 hollow nanofibers is obtained after calcination under nitrogen atmosphere. The resultant mesh demonstrates superhydrophilic/underwater superoleophobic property which is promising in oil/water separation. More importantly, the C,N co-doped TiO2 hollow nanofibers endow the mesh with high photodegradation ability to dyes under visible light. This work draws an affordable but high-performance multifunctional mesh for potential applications in wastewater treatment.

Upper-room ultraviolet germicidal irradiation (UVGI) technology can potentially inhibit the transmission of airborne disease pathogens. There is a lack of quantitative evaluation of the performance of the upper-room UVGI for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) airborne transmission under the combined effects of ventilation and UV irradiation. Therefore, this study aimed to explore the performance of the upper-room UVGI system for reducing SARS-CoV-2 virus transmission in a hospital isolation environment. Computational fluid dynamics and virological data on SARS-CoV-2 were integrated to obtain virus aerosol exposure in the hospital isolation environment containing buffer rooms, wards and bathrooms. The UV inactivation model was applied to investigate the effects of ventilation rate, irradiation flux and irradiation height on the upper-room UVGI performance. The results showed that increasing ventilation rate from 8 to 16 air changes per hour (ACH) without UVGI obtained 54.32% and 45.63% virus reduction in the wards and bathrooms, respectively. However, the upper-room UVGI could achieve 90.43% and 99.09% virus disinfection, respectively, with the ventilation rate of 8 ACH and the irradiation flux of 10 μW cm-2. Higher percentage of virus could be inactivated by the upper-room UVGI at a lower ventilation rate; the rate of improvement of UVGI elimination effect slowed down with the increase of irradiation flux. Increase irradiation height at lower ventilation rate was more effective in improving the UVGI performance than the increase in irradiation flux at smaller irradiation height. These results could provide theoretical support for the practical application of UVGI in hospital isolation environments.

In this study, ferroelectric Bi4Ti3O12 and Au-Bi4Ti3O12 nanofibers were synthesized by electrospinning and ion sputtering. The piezoelectric effect of Bi4Ti3O12 and the surface plasmon effect of Au were used to improve the photogenerated electron–hole separation and optical absorption. The results of the characterization showed successful preparation of the orthorhombic Bi4Ti3O12 nanofibers, in which the absorption band edge was 426 nm with a 2.91 eV band gap. The piezo-photocatalytic activity of the Bi4Ti3O12 was tested through the degradation of the antibiotic ciprofloxacin under three different experimental conditions: light, vibration, and light plus vibration. All of the ciprofloxacin was degraded after 80 min in piezo-photocatalytic conditions, with a piezo-photocatalytic degradation rate of 0.03141 min−1, which is 1.56 and 3.88 times, respectively, that of photocatalysis and piezo-catalysis. After loading Au on the Bi4Ti3O12, the degradation efficiency was improved under all three conditions, and the piezoelectric photocatalytic efficiency of Au-Bi4Ti3O12 for ciprofloxacin degradation was able to reach 100% in 60 min with a piezo-photocatalytic degradation rate of 0.06157 min−1. The results of the photocurrent and impedance tests indicated that the photocurrent density of Bi4Ti3O12 nanofibers loaded with Au is increased from 5.08 × 10−7 A/cm2 to 8.17 × 10−6 A/cm2, which is 16.08 times higher than without loading the Au. This work provides an effective way to improve the conversion efficiency of photocatalysis to degrade organic pollutants by combining the plasmon effect and the piezoelectric effect.

A novel BiOI/TiO2 nano-heterojunction was prepared using hydrothermal and sol-gel methods. The composite material was characterized by X-ray diffraction, ultraviolet-visible diffuse reflection spectroscopy, scanning electron microscopy, and transmission electron microscopy. The crystallinity and response to light of BiOI/TiO2 were controlled by preparation conditions such as the optimal solvent condition and heat treatment temperature. The photocatalytic activity of the BiOI/TiO2 catalyst was examined using benzene as a test molecule. The benzene degradation rate of the composite catalyst under visible light was enhanced compared to pure TiO2, thus reaching 40% of the original benzene concentration, which increased further to >60% after surface acidification. The fluorescence spectra, light current, and electron paramagnetic resonance confirmed that the enhanced activity was attributed to carrier separation by the heterojunction. The acid sites and active chlorine of hydrochloric acidification offer a novel mechanism for photocatalytic reactions.

The synergistic effect of electrostatically enhanced fibrous filtration originates from the charging characteristics of aerosol particles and electret fibers in an electric field. Two electrostatically enhanced fibrous filter systems are designed in this study to investigate the mechanism of the effects of the charging characteristics of oily aerosol on the filtration efficiency. We investigate the charging characteristics and their effects on the filtration efficiency of dioctyl-phthalate (DOP) aerosol particles of various sizes by setting different filter systems and electric field intensities. The experimental results show that the charge of DOP particles increases with the strength of the electric field, and the average charge increases with the particle size. The maximum charge of DOP particles reaches 4760 eC/P, and the filtration efficiency of the coupled system improves when DOP particles are amply charged. For 0.25 μm DOP particles as the most penetrating particle size, the system had good long-term stability, and the filtration efficiency is approximately 72% higher than that of the fiber acting alone. Meanwhile, the problem of oily aerosol deposition reducing the electret filtration efficiency is solved, providing a basis for long-term filtration and oily aerosol purification by electret fiber.

基于半导体异质结原理,设计并制备了新型氯氧铋/二氧化钛复合光催化材料,以甲基橙为目标污染物,研究了氯氧铋制备条件和复合比例对复合材料的光催化特性的影响,随后利用XRD、UV-Vis DRS、TEM、EPR等方法对催化材料进行表征,从表面形貌、自由基等角度,分析其光催化原理.结果 表明,新型复合光催化材料相对氟氧铋、二氧化钛的单体,具有更强的紫外催化能力,对传统有色染料均具有良好的去除效果.这是由于氯氧铋和二氧化钛可以形成半导体异质结,光生电子传递降低了载流子负荷率,羟基自由基生成量增加,因此光催化性能大幅提升.

Some studies have shown that contaminants can be transferred between floors and the soles, and there are few studies on pollutant propagation caused by human walking in real-life situations. This study explored the propagation and diffusion law of ground pollutants from rubber soles to poly vinyl chloride (PVC) floor during indoor walking through employing a fluorescent solution as a simulant. The footprint decay (D) and transfer efficiency (τ) of the fluorescent solution transferred from the sole to the indoor floor during walking were analyzed based on the fluorescent footprint imaging. The effects of namely body weight (50–75 kg), walking frequency (80–120 steps/min), and solution viscosity (oil and water) were also investigated. It was found that the total fluorescence gray value on the ground decreased exponentially as the number of walking steps (i) increased. The relationship between the normalized gray value of the fluorescent solution (D) on each floor panel i was Di=aebi,2.1≤a≤3.8,–1.4≤b≤–0.7, and τ was distributed in the range of 0.51–0.72. All influencing factors had a significant effect on a, and a greater body weight resulted in a smaller a value, while only the body weight had a significant effect on b and τ, and a greater body weight led to larger b and lower τ values.

本文利用溶胶凝胶法制备了溴氧铋/二氧化钛复合光催化材料.以甲基橙为目标污染物,研究了溴氧铋含量对复合材料的可见光催化特性的影响,随后通过表面氯化改性,进一步提升了光催化能力.最后利用XRD、UV-Vis DRS、TEM、EPR等方法对催化材料进行表征,分析其光激发原理.结果表明,新型复合材料具有较好的可见光响应,对有机物的降解能力优于溴氧铋和二氧化钛单体,这是由于二者形成了半导体异质结,光生电子传递降低了载流子复合率,羟基自由基生成量增加,而表面氯化引入了新的氯自由基,进一步提高反应活性.

成功制备了一系列石墨烯/TiO2复合材料并分别氯化改性.以甲基橙和苯酚作为目标污染物,进行复合材料光催化降解活性实验;随后引入电化学和电子顺磁共振技术对该催化剂及其反应体系进行表征,推断其机理.结果表明,石墨烯具有极好的电子迁移能力,可以提高光生载流子的传递效率,进而增强TiO2紫外催化性能.新型复合材料均表现出较高的光催化降解活性,甲基橙降解率由70％提升至100％,苯酚降解率由10％提升至100％.而表面氯化引入了新的活性基团,在光照条件下能够生成氯自由基,进而配合羟基、超氧,形成一种新的三自由基反应体系,使其氧化降解能力大幅提升.

Humidity in the air can significantly limit the adsorption capacity of porous materials used for the removal of chemical warfare agents (CWAs). Therefore, in this work, we prepared a porous organic material (C-1) and its fluoride derivative (C-1-F) via a Schiff base reaction and determined their structure and morphological properties, hydrophobicity, and adsorption capacity. Compared to the parent C-1 material, both the channel and particle surface of C-1-F were highly hydrophobic, thus stabilizing the fluorinated porous material under various humidity conditions. Dimethyl methyl phosphonate was used as a nerve agent simulant to examine the efficiency of the synthesized porous materials, indicating that C-1-F had a higher adsorption capacity than C-1 under dry conditions. Moreover, unlike C-1, the adsorption capacity of hydrophobic C-1-F was not affected even under a relative humidity of 20%, and it is still able to maintain high adsorption capacity at a relative humidity of 60%, suggesting its high application potential in the removal of CWAs.