Distribution characteristics and photochemical effects of isoprene in a coastal city of southeast China.

As forest coverage and urban greening increase in China, the impact of biogenic volatile organic compounds (BVOCs) on urban atmospheric environment cannot be neglected. As one of the most abundant and reactive BVOCs globally, isoprene plays a crucial role in atmospheric radical chemistry. However, the reports on quantifying the impact of isoprene on atmospheric photochemistry remain scarce.

Low-temperature selective catalytic reduction of NO with NH over an FeO /β-MnO composite.

A series of Fe-modified β-MnO (FeO /β-MnO) composite catalysts were prepared by an impregnation method with β-MnO and ferro nitrate as raw materials. The structures and properties of the composites were systematically characterized and analyzed by X-ray diffraction, N adsorption-desorption, high-resolution electron microscopy, temperature-programmed reduction of H, temperature-programmed desorption of NH, and FTIR infrared spectroscopy. The deNO activity, water resistance, and sulfur resistance of the composite catalysts were evaluated in a thermally fixed catalytic reaction system.

Study of the denitration performance of a ceramic filter using a manganese-based catalyst.

A MnO /γ-AlO catalyst was prepared by impregnation of manganese acetate and alumina. After optimizing the composition, it was loaded into a ceramic filter (CF) by a one-step coating method. The results show that MnO /γ-AlO had the best denitration activity when the Mn loading was 4 wt% with a calcination temperature of 400 °C.

Tungsten modified natural limonite catalyst for efficient low-temperature selective catalytic reduction of NO removal with NH: preparation and characterization.

With natural limonite as the precursor and an ammonium tungstate hydrate as modification, the W/limonite composite catalysts were synthesized by the impregnation method. Their structures and properties were systematically characterized and analyzed; the denitrification activity and resistance to water and sulfur on catalysts were investigated. The results indicated that the W/limonite composite with W/Fe mass ratio of 9% and calcination temperature of 300 °C had highly catalytic activity, enhanced resistance to sulfur and water.

Ce(SO)/α-FeO selective catalytic reduction of NO with NH: preparation, characterization, and performance.

To achieve a low-cost, high-activity denitrification catalyst with excellent water and sulfur resistance, goethite and Ce(SO)·4HO were used to prepare Ce(SO)/α-FeO composite catalyst by the impregnation way and investigated the effect of Ce(SO) on the properties of goethite. Ce(SO)/α-FeO with various preparation conditions for denitration was systematically discussed, and its structure and properties were characterized by XRD, BET, TEM, XPS, H-TPR, and NH-TPD methods. The results showed that Ce(SO)/α-FeO over the Ce/Fe molar ratio of 0.

Development of bacterial resistance induced by low concentration of two-dimensional black phosphorus mutagenesis.

The wide use of nano-antibacterial materials has triggered concerns over the development of nanomaterials-associated bacterial resistance. Two-dimensional (2D) black phosphorus (BP) as a new class of emerging 2D nanomaterial has displayed excellent antibacterial performance. However, whether bacteria repeatedly exposed to 2D BP can develop resistance is not clear.

Photochemical reactions between superoxide ions and 2,4,6-trichlorophenol in atmospheric aqueous environments.

The superoxide anion radical (O) is an important reactive oxygen species (ROS), and participates in several chemical reactions and biological processes. In this report, O was produced by irradiating riboflavin in an O-saturated solution by ultraviolet light with a maximum emission at 365 nm. And the contribution of O to 2, 4, 6-trichlorophenol (2, 4, 6-TCP) was investigated by a combination of laser flash photolysis (LFP) and UV light steady irradiation technique.

Decomposition of gaseous chlorobenzene using a DBD combined CuO/-FeO catalysis system.

Copper oxide and hematite (CuO/-FeO) composite catalysts were prepared by using goethite as precursor adopted impregnation way and applied to the dielectric barrier discharge (DBD) catalytic decomposition of gaseous chlorobenzene. The CuO/-FeO composite was characterised by X-ray diffraction, Brunauer-Emmett-Teller method, scanning electron microscopy and X-ray photoelectron spectrometer technique. The decomposition efficiency and energy yield of gaseous chlorobenzene in DBD catalysis system were studied by a function of gas flow rate, initial concentration and input voltage.

Photochemical reactions between 1,4-benzoquinone and O

The superoxide anion radical (O) is one of the most predominant reactive oxygen species (ROS), which is also involved in diverse chemical and biological processes. In this study, O was generated by irradiating riboflavin in an O-saturated solution using an ultraviolet lamp (λ = 365 nm) as the light source. The photochemical reduction of 1,4-benzoquinone (p-BQ) by O was explored by 355-nm laser flash photolysis (LFP) and 365-nm UV light steady irradiation.

Biomaterials cross-linked graphene oxide composite aerogel with a macro-nanoporous network structure for efficient Cr (VI) removal.

Chitosan (CS) is an attractive bio-adsorbent in pollutant removal due to its environment-friendly properties and abundant adsorption sites. However, the weak mechanical properties and strong dissolubility in acidic conditions of CS hinder its wide application. Herein, a facile method was proposed to fabricate polydopamine (PDA) and CS cross-linked graphene oxide (GO) (GO/CS/PDA) composite aerogel for Cr (VI) removal.

Photochemical reaction kinetics and mechanistic investigations of nitrous acid with sulfamethazine in tropospheric water.

Nitrous acid (HONO) is an important atmospheric pollutant that can strongly absorb ultraviolet irradiation in the region of 300-400 nm, as previously reported. Since the solar irradiance that reaches the surface of the earth has wavelengths greater than 290 nm, the photodissociation of HONO is considered the major method of hydroxyl radical formation in the troposphere. Thus, the photoinduced chemical reactivity of HONO is important.

Photochemical oxidation of di-n-butyl phthalate in atmospheric hydrometeors by hydroxyl radicals from nitrous acid.

The photochemical oxidation of di-n-butyl phthalate (DBP) by OH radicals from nitrous acid (HONO) in atmospheric hydrometeors was explored by two techniques, steady-state irradiation, and laser flash photolysis (LFP). The effects of atmospheric liquid parameters on DBP transformation were systematically evaluated, showing that DBP does not react with HONO directly and OH-initiated reactions are crucial steps for consumption and transformation of DBP. Two reaction channels are operative: OH addition and hydrogen atom abstraction.

Photochemical transformation of dimethyl phthalate (DMP) with N(iii)(HONO/HONO/NO) in the atmospheric aqueous environment.

The photochemical transformation of dimethyl phthalate (DMP) with N(iii)(NO/HONO/HONO) was investigated using 365 nm steady-state irradiation and 355 nm laser flash photolysis (LFP) techniques. The results showed that N(iii) concentration, DMP initial concentration and pH values all strongly affected the oxidation efficiency of DMP. The primary step of the reaction was the attack of ˙OH radicals on the aromatic ring to form a DMP-OH adduct, and the bimolecular rate constant was determined to be (5.

Kinetics analysis of interfacial electron-transfer processes in goethite suspensions systems.

The photochemical behavior of goethite has been one of the most important topics in the field of environmental science due to it plays a significant role in the removal and transformation process of numerous pollutants. However, the interfacial electron transfer process of goethite is not clear. Using a nanosecond laser flash photolysis spectrometer, we report the transient spectroscopic observations of interfacial electron-transfer reactions in goethite dispersion under UV irradiation.

Performance of selective catalytic reduction of NO with NH over natural manganese ore catalysts at low temperature.

Natural manganese ore catalysts for selective catalytic reduction (SCR) of NO with NH at low temperature in the presence and absence of SO and HO were systematically investigated. The physical and chemical properties of catalysts were characterized by X-ray diffraction, Brunauer-Emmett-Teller (BET) specific surface area, NH temperature-programmed desorption (NH-TPD) and NO-TPD methods. The results showed that natural manganese ore from Qingyang of Anhui Province had a good low-temperature activity and N selectivity, and it could be a novel catalyst in terms of stability, good efficiency, good reusability and lower cost.

Photochemical reaction between biphenyl and N(III) in the atmospheric aqueous phase.

The photochemical reaction between biphenyl (Bp) and N(III) under irradiation at 365 nm UV light was investigated. The results showed that Bp conversion efficiency was strongly influenced by N (III) concentration, Bp initial concentration and pH. Species-specific rate constants determined by reaction of Bp with HONO (k), HONO (k) and NO (k) were k = (0.

[Preparation of -FeO Catalyst by Heat Treatment of Natural Limonite for Selective Catalytic Reduction of NO by NH].

Natural limonite was used as a precursor to prepare -FeO via thermal treatment. The influences of reaction temperature, manganese oxides existing in limonite and coexisting SO and HO on the catalytic reduction activity of the prepared-FeO were evaluated, and the activity of SCR was compared with that of -FeO, by means of XRD, XRF, XPS, NH-TPD, FT-IR and so on. The results showed that because the surface acidity of -FeO is stronger, the SCR temperature window of -FeO was 200-350℃ being broader than that of -FeO (200-300℃), and in the active temperature window, the NO removal reached over 99%.

[Photocatalytic Degradation of Gaseous Toluene by a Photo-Fenton Reaction].

In this study, the performance of photo-Fenton reaction on decomposition of toluene was investigated by a flowing column using toluene as a representative of volatile organic pollutants (VOCs). The effects of initial pH, H2O2 concentration, Fe2+ concentration, initial concentration of toluene on degradation of toluene by photo-Fenton reaction were evaluated. Mass spectrometry and gas chromatograph were utilized to detect the products.

[Photolysis of Gaseous HNO3 on the α-Fe2O3 Films Under 308 nm UV Light].

Under 308 nm UV light, photolysis of HNO3 in the gas phase and on the α-Fe2O3 films was studied by using ultraviolet-visible spectrophotometer (UV-Vis), Fourier transform infrared spectrometer (FTIR) combined with ion chromatography (IC) technique. The effects of HNO3 initial concentration, relative humidity (RH) and illumination time were systematically investigated. Results showed photolysis of HNO3 could produce NO2 and NO in the gas phase and on the α-Fe2O3 films.

PAHs in sediment cores at main river estuaries of Chaohu Lake: implication for the change of local anthropogenic activities.

In the present study, 28 polycyclic aromatic hydrocarbons (PAHs) were investigated in four sediment cores collected from the main river estuaries of Chaohu Lake, one of the severely polluted lakes in China. The results indicate that elevated concentrations of total PAHs (Σ28PAH) were found in the samples from the estuary of Nanfei River (ENF), considering BaP-based total toxicity equivalent (TEQ-BaP) and toxic unit (TU) results; there are potential adverse environmental implications. The total organic carbon (TOC) played an important role on the accumulation of PAHs at ENF and the estuary of Tongyang River (ETY).

PAHs in the Chinese environment: levels, inventory mass, source and toxic potency assessment.

This paper presents a systematic but preliminary study on the levels, inventory mass, emission sources and risk of exposure to PAHs in China by examining 14 polycyclic aromatic hydrocarbons (from the 16 priority PAHs listed by the U.S. EPA, excluding naphthalene and acenaphthylene) in four main environmental media (air, water, soil and sediment).

Photolysis of glycolaldehyde in the 280-340 nm region.

We have investigated the gas-phase UV photolysis of glycolaldehyde (HOCH(2)CHO) by laser photolysis combined with cavity ring-down spectroscopy. Absorption cross sections of glycolaldehyde in the 280-340 nm region were measured by cavity ring-down spectroscopy. The HCO + CH(2)OH and the OH + CH(2)CHO product channels following the photolysis of glycolaldehyde were directly examined.

308 nm photolysis of nitric acid in the gas phase, on aluminum surfaces, and on ice films.

We have studied the photolysis of nitric acid (HNO(3)) in the gas phase at 253 and 295 K, on aluminum surfaces at 253 and 295 K, and on ice films at 253 K, by using 308 nm excimer laser photolysis combined with cavity ring-down spectroscopy. We monitored both the ground-state NO(2) and the electronically excited NO(2), NO(2)*, produced from the HNO(3) photolysis. NO(2)* + OH is a predominant photolysis pathway (if not the only photolysis pathway) from the gas-phase photolysis of HNO(3) at 308 nm.

Photochemistry in the mixed aqueous solution of nitrobenzene and nitrous acid as initiated by the 355 nm UV light.

The 355 nm photon-initiated microscopic reaction mechanisms of the mixed aqueous solution of nitrobenzene and nitrous acid in the presence or absence of O(2) were studied by the laser flash photolysis technique. The main transient absorption peaks in the recorded spectra were assigned and the growth/decay trends of several transient species were investigated. It was found that the OH radical formed from the photolysis of nitrous acid triggered most of the subsequent radical reactions.