Concurrent removal of Cr(III), Cu(II), and Pb(II) ions from water by multifunctional TiO2/Alg/FeNPs beads

The use of multifunctional materials for water remediation is a modern approach where adsorption phenomena and heterogeneous photocatalysis can be applied for the removal of pollutants. Since the ideal remediation system should be able to remove both organic and inorganic pollutants, a crucial aspect to consider is the knowledge of operational parameters affecting the removal process, especially when heavy metal ions are present in concoction as in real systems. Given the proven efficiency of multifunctional TiO₂/Alg/FeNPs magnetic beads for the removal of model organic pollutants, this study investigated the possibility to exploit such system also for the removal of mixed heavy metals (MHM), specifically Cr(III), Cu(II), and Pb(II) ions, under ultraviolet irradiation at a wavelength of 254 nm. After a preliminary screening on the optimal catalyst loading, operating parameters such as the initial concentration of metal ions, contact and irradiation time, and pH were investigated to optimize the removal of metal ions using response surface methodology (RSM) via Box–Behnken design. Starting from a MHM solution containing 44 ppm of each metal ion, the removal of Pb(II), Cr(III), and Cu(II) ions in the aqueous solution was nearly completed (>98.4%) for all three ions within 72 min of irradiation at almost neutral pH (pH = 6.8). The stability of TiO₂/Alg/FeNPs was confirmed by retrieving and reusing the beads in three consecutive cycles of heavy metals removal without observing significant changes in catalyst efficiency.     

Iron oxide nanoparticles supported on biogenic silica derived from bamboo leaf ash for rhodamine B photodegradation

This research demonstrates the use of biogenic silica derived from bamboo leaf ash as a support for iron oxide nanoparticles. The preparation includes silica extraction from bamboo leaf ash and iron oxide nanoparticle impregnation into the silica gel under hydrothermal conditions, which is followed by calcination at 400 °C for 2 h. The physicochemical characterization includes X-ray diffraction analysis, gas sorption analysis, scanning electron microscopic analysis and transmission electron microscopic analysis. The light absorption capability and the band gap energy of the materials were determined by diffuse-reflectance UV–visible spectrophotometry. The materials obtained by varying the Fe content to 5 and 10% wt. were evaluated in rhodamine B photocatalytic degradation and photooxidation systems. It was found that the materials have a combined hematite and magnetite nanostructure, with the ratio of 9:10, and the particle sizes range from 10 to 40 nm. With a band gap energy of 2.27 eV, the prepared materials produce the successive photocatalytic degradation of rhodamine B. It was clarified that the formation of composite enhances stability and reusability of photocatalyst as shown by the stable initial rate at wide pH range and reuse for 5 cycles. Degradation mechanism is enhanced by the addition of H₂O₂ as an oxidant, and the investigation of the effect of scavengers shows that the degradation rate not only depends on radical formation but also on other species related to the formation of oxidizing agent.     

杂多酸光催化还原回收废水中银的试验探讨

目的回收处理废水中的银离子。方法采用杂多酸作光催化剂在紫外光照射下回收废水中的重金属银离子。探讨异丙醇浓度、磷钨杂多酸浓度、光照时间、银离子浓度等因素对光催化还原废水中银离子回收率的影响。结果在最优化实验条件下,杂多酸光催化还原回收处理废水中银离子的回收率达99．63％。结论可将杂多酸作光催化还原剂应用于处理和回收废水中的银离子。     

新型等离子体与光催化复合空气净化技术研究

目的 研究一种新型的等离子体-光催化复合空气净化技术.方法 采用三氯乙烯气体作为空气污染物对等离子体单元和光催化单元进行复合试验,选择等离子体加光催化或光催化加等离子体两种复合方式、改变两者之间的距离以及在其间放置网状物,检测其对三氯乙烯的净化效率.结果 等离子体加光催化复合方式具有明显协同效应,而且在两者的单独净化效率较低时更明显;两者间距在32.5 cm时净化效率可以达到90%以上;放置网状物对其净化效率都具有影响,放置不锈钢网时降解率为76.3%,放置无纺布时降解率为79.2%.结论 采用等离子体加光催化的复合方式、保持合适的间距,并放置适当材料的网,具有较显著的协同促进效应,可提高净化技术的复合效应.     

纳米光触媒杀菌抑菌效果及临床试验研究

目的探讨改善医疗环境的新方法,降低环境因素所引起的医院感染。方法采用纳米光催化技术,对医疗环境进行临床条件下杀菌抑菌效果分析。结果生化衣纳米光触媒喷涂材料对现场3种环境物体表面杀菌作用明显,物体表面总的细菌消亡率为23.75%~38.30%;垂直表面细菌消亡率为48.77%~87.97%,水平表面细菌消亡率为12.50%~77.20%,空气细菌消亡率为1.52%~60.00%。结论采用纳米光触媒进行医疗环境消毒和净化具有很好的发展前景。     

稀土元素在光催化降解抗生素中的应用研究进展

摘要：抗生素广泛应用于医疗和农业生产之中,由于传统的废水处理工艺不能够有效地去除废水中的抗生素,导致目前环 境中已经广泛检测到抗生素的存在。为了预防抗生素污染扩散带来的危害,人们投入了大量的资源研究抗生素的去除方法。本 文参考国内外文献总结了近几年稀土元素在光催化降解抗生素中的应用研究情况,深入揭示了稀土元素在光催化降解抗生素应 用中发挥的作用。主要内容包括：稀土元素掺杂、稀土元素参与构建异质结和稀土元素掺杂与异质结共用的光催化降解;稀土 元素应用在光催化降解抗生素中的3种方法的分析对比;对稀土元素应用于光催化降解抗生素的未来展望。     

The noncellular reduction of MTT tetrazolium salt by TiO2 nanoparticles and its implications for cytotoxicity assays

We report results of noncellular tests, revealing the occurrence of photocatalytic interactions between titanium dioxide (TiO₂, titania) nanoparticles and the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide] cytotoxicity indicator. These interactions induce the reduction of MTT and formation of purple formazan under biologically relevant conditions. Classical MTT assays have been performed to evaluate the production of formazan in DMEM-F12 and RPMI-1640 cell culture media (containing 10% fetal bovine serum-FBS) treated with Degussa-P25 TiO₂ nanoparticles, in the absence of cells. The colorimetric determinations revealed the noncellular MTT to formazan transformation induced by TiO₂ nanoparticles, under conditions commonly used for in vitro cytotoxicity testing of nanomaterials. The formazan precipitation was found to be proportional to the TiO₂ concentration, being enhanced under laboratory daylight exposure. The photocatalytic nature of the studied effect was assessed under UV irradiation at 365 nm. The biological significance of the reported reaction was established with respect to cellular reference experiments performed on V79-4, HeLa and B16 cell lines. The results show false viability increases with up to 14% (for TiO₂ concentrations generally higher than 50 μg/ml), induced by the TiO₂–MTT reaction. This type of artifacts may lead to underestimated toxicity or false proliferation results.     

Seawater activated TiO2 photocatalyst for degradation of organic compounds

The world's oceans are polluted by a continuous inflow of plastic. Plastic fragments finally into microplastic, which can be taken up, for example by plankton, and subsequently by the entire ocean food web. An approach to reduce plastic pollution constitutes the accelerated microplastic degradation in marine environments. TiO₂ (anatase) is commonly used as an oxidative photocatalyst and well known to catalyze the degradation of organic compounds upon UV irradiation.In this study, a selective activation of TiO₂ (anatase) particles encapsulated by Ca- or Sr-polyphosphate is presented. The TiO₂ polyphosphate core-shell particles are envisaged as additives in plastic products. The highly concentrated cations from seawater, viz. Na⁺ and Mg²⁺, displace the Ca²⁺ or Sr²⁺ cations from the polyphosphate shell. As a result, the polyphosphate coating dissolves and thus the photocatalytically active TiO₂ core is released. The stability of the TiO₂ polyphosphate particles in potable water and the seawater activated disintegration of methylene blue, methyl methacrylate, terephtalic acid, and poly(vinyl alcohol) was shown. It has been demonstrated, that the sweetwater stable polyphosphate coating degrades in the presence of seawater, which could be monitored by the activation of the TiO₂ (anatase) photocatalyst.     

Physicochemical and photocatalytic activity of hematite/biochar nanocomposite prepared from Salacca skin waste

This study involves the preparation of hematite/biochar (HBC) nanocomposite and its photocatalytic evaluation for methylene blue degradation. HBC material was synthesized based on carbonization of iron oxide precursor-treated Salacca skin powder. Characterization studies of the material were carried out using x-ray diffraction, scanning electron microscope-energy dispersive x-ray, transmission electron microscope, and gas sorption analysis. Dispersed Fe₂O₃ with sizes ranging from 20 to 50 nm in the nanocomposite were identified, showing a band gap energy of 2.21 eV. Results show that the material demonstrates suitable physicochemical performance for photocatalytic application. By varying the initial concentration of methylene blue, it is noted that the decolorization obeys pseudo-first-order kinetics and fits the Langmuir-Hinshelwood mechanism. The decolorization kinetics was observed to be at optimum level at pH 7, reaching this state with a catalyst dosage of 0.5 g/L. The performance of the photocatalyst was observed to be better with H₂O₂ addition, in which the decolorization efficiencies reach 99.9% for all varied initial concentrations with 1 h treatment.     

Studies on the oxygenation of human blood by photocatalytic action

Abstract:  The present article gave the proof of concept for oxygenating human blood using the established principles of photocatalytic action of anatase TiO₂ thin films in generating oxygen from water. The photocatalytic action involves the absorption of the UV optical energy (365 nm) to split water available in the blood into oxygen and hydrogen, and the generated oxygen is attached to the hemoglobin. In the present study, an enhanced catalytic action was achieved by preparing the nanosized anatase TiO₂ thin films on tin-doped indium oxide (ITO) thin films, forming TiO₂/ITO semiconducting junction. These TiO₂ and ITO thin films and the semiconducting junctions were grown by the reactive DC Magnetron sputtering technique (using pure metallic targets) at room temperature (300 K) and subsequently annealed at 870 K for 60 min. The annealing process (i) influenced the formation of the anatase phase of TiO₂; and (ii) diffused indium from ITO into TiO₂, forming InTi₂O₅. The work functions of ITO and InTi₂O₅ were measured to be 4.72 and 4.76 eV, respectively. The higher efficacy of the photocatalytic action was attributed to the lower work function of ITO. The results clearly show that the photocatalytic action increases the oxygen content in the blood significantly.