Z-机制g-C3N4/Bi/BiOBr异质结光催化剂制备及其可见光降解甲醛气体研究

通过将BiOBr纳米片与g-C₃N₄复合,然后原位还原,合成了具有纳米花状结构的三元异质结光催化剂g-C₃N₄/Bi/BiOBr.对g-C₃N₄/Bi/BiOBr的结构、形貌、元素价态和光学性能等进行了表征和研究.评估了g-C₃N₄/Bi/BiOBr对气体甲醛的光催化降解活性. g-C₃N₄/Bi/BiOBr在可见光照射下降解甲醛的活性与g-C₃N₄、 BiOBr单体和g-C₃N₄/BiOBr二元复合物相比显著提高. 20%-g-C₃N₄/Bi/BiOBr复合物可以在60 min内(λ> 400 nm)降解80%的气态甲醛(初始浓度0.16 mg·L^-1).     

Assembled Organoruthenium(II) for Formaldehyde Decomposition and Hydrogen Production

Formaldehyde decomposition is not only an attractive method for hydrogen production, but also a potential approach for gaseous formaldehyde removal. In this research, we prepare some assembled organoruthenium through coordination reaction between Ru(p-Cymene)Cl₂ and bridge-linking ligands. It is a creative approach for Ru(p-Cymene)Cl₂ conversion into heterogeneous particles. The rigidity of bridge-linking ligand enables assembled organoruthenium to have highly ordered crystalline structure, even show clear crystal lattice with spacing of 0.19 nm. XPS shows the N−Ru bond are formed between bridge-linking ligand and Ru(p-Cymene)Cl₂. The assembled organoruthenium has high abundant active sites for formaldehyde decomposition at low temperature. The reaction rate could increase linearly with temperature and formaldehyde concentration, with a TOF of 2420 h⁻¹ at 90 °C. It is promising for gaseous formaldehyde decomposition in wet air or nitrogen. Formaldehyde conversion is up to 95 % over Ru-DAPM is 4,4′-diaminodiphenylmethane at 90 °C in air. Gaseous formaldehyde decomposition is a two-steps process under oxygen-free condition. Firstly, formaldehyde dissolve in water, and be converted into hydrogen and formic acid through formaldehyde-water shift reaction. Then intermediate formic acid will further decompose into hydrogen and carbon dioxide. We also find formaldehyde decomposition is a synergetic catalysis process of oxygen and water in moist air. Oxygen is conducive to formic acid desorption and decomposition on the active sites, so assembled organoruthenium exhibit slightly higher conversion for formaldehyde decomposition in moist air. This work proposes a distinctive method for gaseous formaldehyde decomposition in the air, which is entirely different from formaldehyde photocatalysis or thermocatalysis oxidation.     

Sponge-nested polymer monoliths: Versatile materials for the solid-phase extraction of bisphenols

Polymer monoliths are promising materials for sample preparation due to their high porosity, pH stability, and simple preparation. The use of melamine formaldehyde foams has been reported as an effective support to prepare highly robust silica and polymer monoliths. Herein, divinylbenzene monoliths based on a 50:50 (%, w/w) crosslinker/porogen ratio have been nested within a melamine-formaldehyde sponge, resulting in monoliths with a surface area higher than 400 m²/g. The extraction performance of these monoliths was evaluated for the extraction of endocrine-disrupting bisphenols from aqueous solutions. We evaluated for the first time the versatility of sponge-nested polymer monoliths by comparing three different extraction modes (vortex mixing, magnetic stirring, and orbital shaking). Vortex mixing showed a comparable recovery of bisphenols (39%–81%) in a shorter extraction time (30 min, instead of 2 h). In addition, the robustness of the sponge-nested polymer monoliths was demonstrated for the first time by reshaping a larger monolithic cube (0.125 cm³) into four smaller pieces (4 × 0.03125 cm³) leading to a 16%–21% increase in extraction efficiency. This effect was attributed to an increase in the effective contact area with the sample, obtaining a higher analyte extraction capacity.     

负载型廉价金属催化剂在低温催化氧化甲醛中的应用

甲醛是室内常见的挥发性有机污染物之一,长期接触会严重危害人体健康。负载型廉价金属催化剂在甲醛去除和实际应用方面表现出优异性能,引起研究人员的广泛关注。本文阐述了低温条件下负载型廉价金属催化剂在甲醛热催化氧化、光催化氧化和等离子协同催化氧化方面的研究进展,介绍了甲醛低温催化的影响因素,并讨论了反应机理。反应条件、载体类型和制备方式是影响甲醛低温催化活性的重要因素。虽然负载型廉价金属催化剂在甲醛光催化氧化和热催化氧化方面均表现出良好性能,但仍须进一步探究提升其在可见光和室温下的催化活性。对于甲醛等离子协同催化氧化,降低反应过程所产生的副产物和能耗仍是研究重点。此外,本文还对负载型廉价金属催化剂在甲醛催化应用中的发展方向进行了展望。     

A New Nanocomposite Based on Pt-rGO Embedded Polymelamine Formaldehyde Nanocomposite for Reduction of Carbon Dioxide

Here, polymelamine formaldehyde was decorated on the surface of reduced graphene oxide whose surface was then electrodeposited with a sub-monolayer of platinum nanoparticles. The nanocomposite thus prepared was characterized using several spectroscopic methods. Using the nanocomposite as a potential electrocatalyst for carbon dioxide reduction, the products were detected by Raman spectroscopy, gas chromatography, ¹³C-NMR spectroscopy, and gas chromatography-mass spectrometry. The analytical results identified methanol as the main product of CO₂ reduction. Moreover, analysis of the liquid products confirmed methanol as the predominant product with a current density of 0.4 mA/cm and a Faradaic efficiency of 93 %.     

Theoretical investigation of the interaction between the metal phthalocyanine [MPc]a(M = Sc,Ti, and V; a = –1, 0, and +1) complexes and formaldehyde

Formaldehyde (FA, CH₂O) is one of the toxic volatile organic compounds that cause harmful effects on the human body. In this work, the interaction of FA gas with metal phthalocyanine (MPc) molecules was studied by employing density functional theory calculations. A variety of [MPc]^a (M = Sc, Ti, and V; a = –1, 0, and +1) complexes were studied, and the electronic properties, interaction energies, and charge transfer properties of all of the studied molecules were systematically discussed. Among the studied complexes, the Sc and Ti phthalocyanines were more reactive toward the adsorption of FA gas. Moreover, it was revealed that the interaction of the [ScPc]⁺¹ and [TiPc]⁰ complexes with the CH₂O molecule was stronger, in which the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap of 46% and 36% decreased after FA adsorption. The results indicated that the MPc-based materials may be a promising candidate for the detection of FA gas.     

活化硅胶表面Fe~(3+)的担载及其对甲醛的催化氧化

硅胶颗粒经过400℃高温活化后与四氯化硅在无水四氢呋喃溶剂中反应制得氯化硅胶。氯化硅胶再经乙酰胺修饰,制备得到表面含羰基和氨基的硅胶修饰体。此组装体具有良好的配位能力,能够与Fe3+进行配位,从而得到表面催化活性点均匀分布的负载型催化剂。该催化剂对甲醛催化氧化具有良好的催化性能,最高催化效率高达91.3%。     

功能化离子液体液化木粉及其酚醛复合材料

合成了氯代1-(2-羟乙基)-3-甲基咪唑离子液体[He MIM]Cl、溴代1-乙胺基-3-甲基咪唑离子液体[Ae MIM]Br和氯代1-羧乙基-3-甲基咪唑离子液体[Ce MIM]Cl 3种功能化咪唑离子液体,并分别进行了红外与氢核磁结构表征.然后用3种离子液体液化木粉,液化3 h后向体系直接加入苯酚、甲醛和氢氧化钠,制备酚醛复合材料,并采用FTIR、XRD、DSC和SEM对酚醛复合材料进行结构、性能与形貌测试,研究离子液体种类对木粉液化率及酚醛树脂性能的影响.结果表明,离子液体及其液化木粉产物制备的酚醛复合材料性能得到明显改善.[Ce MIM]Cl液化效果最好,90℃液化率高达24.6%,当[Ce MIM]Cl与木粉质量比为10∶1时,制备的酚醛复合材料的游离醛释放量由原来的3.64%降低到0.92%.离子液体[Ae MIM]Br能将酚醛复合材料的冲击强度由原来的0.93 k J/m2提高到6.96 k J/m2,而[Ae MIM]Br及其液化的木粉产物制备的酚醛复合材料拉伸强度从原来的3.28 MPa提高到9.70 MPa.     

Probing nanocolumnar silver nanoparticle/zinc oxide hierarchical assemblies with advanced surface plasmon resonance and their enhanced photocatalytic performance for formaldehyde removal

Recent advances in photocatalysis focus on the development of materials with hierarchical structure and on the surface plasmon resonance (SPR) phenomenon exhibited by metal nanoparticles (NPs). In this work, both are combined in a material where size‐controllable Ag‐NPs are uniformly loaded onto the hierarchical microporous and mesoporous and nanocolumnar structures of ZnO, resulting in Ag‐NP/ZnO nanocomposites. The embedded Ag‐NPs slightly decrease the hydrophobicity of fibrous ZnO, improve its wettability, and increase the absorption of formaldehyde (H₂CO) onto the photocatalyst, all of this resulting in excellent photodegradation of formaldehyde in aqueous solution. Besides, we found that Ag‐NPs with optimal size not only accelerate the charge transfer to the surface of ZnO, but also strengthen the SPR effect in the intercolumnar channels of fibrous ZnO particles combining with high concentration of photo‐generated radical species. The micro‐to‐mesoporous ZnO is like a nanoarray packed Ag‐NPs. With Ag‐NPs of diameter 2.5 < ? < 6.5 nm, ZnO exhibits the most superior photodegradation rate constant value of 0.0239 min^?1 with total formaldehyde removal of 97%. This work presents a new feasible approach involving highly sophisticated Ag‐NP/ZnO architecture combining the SPR effect and hierarchically ordered structures, which results in high photocatalytic activity for formaldehyde photodegradation.     

Determination Of Formaldehyde And Acetaldehyde Associated To Atmospheric Aerosols By HPLC

Abstract

A rapid new analytical protocol was developed for the determination of formaldehyde and acetaldehyde associated to atmospheric particulate matter, at ng/m³ levels. The aerosols were collected on glass fiber filters (8″×10″) at face velocities ranging from 15 m/min to 23 m/min. Aliquots of 15.4 cm² were sonicated, for 20 min, with 5.0 mL of 0,01% 2,4-dinitrophenylhydrazine (DNPH), 1 % phosphoric acid. The liquid phase was then filtered and the separation and quantification of the corresponding 2,4-dinitrophenylhidrazone (DNPHo) derivatives carried out by reverse phase HPLC. Acetonitrile:water (57:43, v/v) as mobile phase at 1.0 mL/min and absorbance detection at 350 nm and 365 nm for, respectively, formaldehyde-DNPHo (0.04 AUFS) and acetaldehyde-DNPHo (0.01 AUFS) were used. The precision for four different aliquots, from a 8″×10″ glass fiber filter, were under 0.04% for formaldehyde and 14.16 % for acetaldehyde. In Salvador, Bahia, Brazil, formaldehyde and acetaldehyde were determined, respectively, in the range of 6.8 ng/m³ to 27.3 ng/m³ and 9.1 ng/m³ to 54.6 ng/m³.